you mean you wish your physics teacher taught you about tube amps?? yeah, me too 😆 for real though, Uncle Doug is an excellent teacher and that's a skill in and of itself, on top of his skill with tube amps. i bet he would make an excellent lesson on literally anything on which he is well informed.
I have learned more from @Uncle Doug about vacuum tube/valve electronics than I ever did working on my ee major. I can't thank you enough for all the work you do, sharing your invaluable knowledge.
Exactly, again the old saying, They don't teach you this in school. I have learned more in one month of Doug videos about tube amps, than I can imagine. Very well presented with everyday English language.
Amen. I was a technician in the Air Force. I was trained in Electronic Principles twice, with years of other formal training for electronic and electrical; yet, I emerged from all that training without being able to explain how to bias something. I often marvel at my notes that I took - I recognize the hand writing, but I suppose I held that information long enough to pass a test then dumped it. And in a nuclear weapon system, the troubleshooting is very narrow and clearly defined. One must have certain certifications to troubleshoot beyond what the book says for obvious reasons. But - watching Uncle (Professor) Doug has blown the door open for me and I'm recalling things I learned ins 1984. And the best part of all: I'm having FUN! I retired a few months ago for medical reasons and dreaded it. Now, holy cow - I'm digging into this and having a blast! I should've retired sooner to do this!
1.) My use of the phrase "plate resistor" to describe the 4.7/3.3 Meg wet or dry reverb resistor is meant figuratively (i.e. to describe its function), not literally. 2.) My definition of "Clipping" was inadvertently "clipped" from the video. Here is a proper definition: Clipping is waveform distortion that occurs when amplifier output tube(s) are overdriven and forced to deliver an output voltage or current beyond their maximum capability. Clipping is highly undesirable in both SS and HiFi circuits, while it is often utilized in tube amplification to enhance guitar tone. Crossover distortion, however, sounds awful and is never desirable. 3.) Clean "headroom" is the term used to describe the maximum amount of amplifier output possible before clipping begins. Maximum RMS output power is routinely measured pre-clipping, i.e. clean headroom only. 4.) I inadvertently expressed the decibel scale as being linear instead of logarithmic, during my explanation of gain vs volume. I should have stuck with "volts" instead ;) 5.) A few viewers have commented on the audio quality during the bias comparison. Recall that this is a "recording of a recording" so any artifacts are essentially doubled.
Excellent video Uncle Douglas. It appears from oscilloscope outputs that the crossover distortion shoulders are present at low and high amplifier output/gain. Whereas clipping type distortion occurs when the amplifier volume is cranked past a specific level. Can our ears pick up crossover distortion? Cheers from down under.
Imagine the confusion at the electronic stores with lines of people asking for wet resistors. Demanding to get them, small riots breaking out. Anarchy. Society breaks down and cats take over the world
Everyone out there in you tube land needs to see this.. absolutely broken down to the ground and built back up with full explanation for what you did. Then break down the differences between a 900 to 4+k fender amp . With fantastic guests commentary towards the clipping. Uncle doug busting there butts . Thank you . We all love you and wish you well . Cheers ! .
Bless you Uncle Doug for sharing your wisdom with us. I have always wondered how changing component values in the Tone Circuit effects the Tone and Frequency Response:) You are an amazing Educator and Instructor. I am a visual learner and you have always exceeded all my expectations. Your educational videos will be used as a historical reference archive for this generation and generations to come. Your an honorable and humble man spreading love to all your viewers. Great Karma in your community!!!
Thx uncle Doug . Your videos bring happiness and a light of hope lately. 2020 is the worse year so far in my life. Thank you so much. Hope you have a great day.
best electronic teacher/engineer I've heard explanations spot on. I have qualification in industrial electronics all for solid state micro processors and digital I always wanted to learn about vacuum tube technology and now I have learned from the master. I am now servicing my own valve amps and building valve equaliser preamps. You do have the best voice, very therapeutic.
The amp sounded at it's best at the highest bias level tested. The bass tightened up, and the highs and mids sounded more defined. I guess I'm not too surprised by the results. The tubes were designed and engineered to run optimally around 70% plate dissipation. Anything below that did not sound great at all. I would say that 60% is even too low. I would be curious to hear what 65% sounds like. I'm also curious how it would sound at above 70% up to the point of redplating. Perhaps that test would be better done with a fresh set of tubes.
Thanks so much, Jason. I agree that the 60% to 70% range was the sweet spot. I doubt that going beyond 70% would yield any significant improvement in tone.
A great presentation as always. Hypothesis, experimentation, validation and calibration very clearly and concisely presented. Also room for the subjectivity that is real, meaningful, and at the heart of all music. Bravo!
You're a national treasure, sir. After 2 days of searching fruitlessly for any useful content to help this first-timer bias a 1972 Earth B-2000 for its 4 new 6L6WXT+ tubes, I found your videos and not only biased the amp with no problem, I can now understand simple schematics as well as how tubes actually work. I can't thank you enough.
Mi estimado Uncle Doug, it is amazing the teaching skills you have, you was, if not in this life in some past, the best "Maestro" I've ever known or existed. Me quito el sombrero para saludarlo! Un fuerte abrazo desde Mexico.
Dear U.D : The quality of this channel is unmatched! Thank you so much for your generosity and willingness to share your knowledge with us. As usual : you the man! 🤘🏼
If your looking for how to videos on building any kind of amplifier THIS is the right place. Congratulations on a wonderful explanation on this particular part of practical amp design Uncle Doug. You and Mr. Paul Carlson are the best teachers when it comes to electronics design on UA-cam in my honest humble opinion!
i can definitely hear the goodness at 60% and 70%. Good looking DR you have there Doug! I have a Blackface DR myself and it's biased around 68% because that's what sounds good to my ears. Another excellent video sir! Many Thanks!
That was an outstanding educational video that described complicated electronic principles in a way a layman can understand and it answered so many questions that Fender lovers have wondered for years...you should be proud of yourself Uncle Doug.....thank you for the knowledge...Keep up the great work!!
Always good to see someone dispel amplifier myths and half-truths through the application of science. Maybe next you could convince guitarists that measuring DC resistance of pickups in isolation doesn't tell them anything about the output voltage!
I think I speak for everyone when I say we greatly appreciate you using the dummy load, Doug. I also want to echo the sentiments of the other commenters and add that as someone who only recently started to gain (pun intended) an interest in the science of amplifiers, this exhaustive test/explanation/lesson on both an objective AND subjective front, you left no stone unturned and I didn't feel as though I was expected to fully understand a litany of technical vocabulary to learn from you. The long and short of it is this: Thank you for being a great teacher!
Bless you Uncle Doug for another amazing educational video. We are all locked down, so we turn off the TV and turn on Uncle Doug's inspirational videos. We want more:)
Uncle Doug can you get me some schematics on your volt and amp meter that you put your tubes in to measure the amps and volts on the match tube.s@@UncleDoug
As someone who enjoys working on my own Fender amps but does so with enough knowledge to be dangerous, your videos help keep me out of trouble by being my first "Go-To" reference. I've learned so much from you and continue to learn something new with every video you post. Many thanks for sharing your knowledge, experience, and insights - it's a great privilege to be in your virtual classroom. And your 4 legged teaching assistants help make these even better! Bravo, and many thanks, Uncle Doug!
I love when you go through schematics and explain in detail what is going on, etc. This is what makes your channel so so so special, your ability to teach in a very direct and understandable way, show us what is happening in the amps physically and then show us again on paper. Very comprehensive. I LOVE YOUR TECHNICAL VIDEOS TO DEATH.
Thank you Uncle Doug. You made sense out of the hours of videos with conflicting information and over or under technical detail and just plain nonsense that i have endured trying to learn the skill of tube amp biasing. This is the last video i need to watch on the subject, i wish it had been the first. Thank you Sir.
Hi from England...heard about Uncle Doug's" valve channel" only this evening from a friend.We both have a collection of valve "babies",Fender blues juniors,Vox AC15's,Peavey delta Blues,and right back to a 1958 Watkins dominator...I am amazed at the wealth of information that is available here...an absolute gold mine for us" tone hounds"....and delivered with an authority and conviction that is easily absorbed,even if you don't have a major in electronics ..thanks Uncle Doug,keep them coming....and Stay Safe.......Dave ..midnight and still watching!
Unless your dream amp (circuit) already exists, or you’ve already built it, I’d like to see you build one. All the bells and whistles. I’ve seen about 90% of your videos now. Going into reruns to reinforce what I’ve learned. I bought a late 50’s Stromberg Carlson AU57 PA amp and had the schematic blown up to blueprint size. It has 4 inputs, 5 12AX7’s, 2 6L6G’s, 2 12AU7’s, a 5U4GB, and a 6X4. I’m not sure if I’m going to restore it or turn it into something else at this point. Should be an interesting winter project.
I love your technical videos. I am almost confident enough to tackle an amp build myself because of how well you explain things. I’ve gone back and watched all of your old tutorial videos multiple times.
@@mrman3565 The first recorded use of 'kid' as a colloquial term for 'human child' was in the 16th century. By the time Charles Dickens used it in 'Oliver Twist' it had been in use for over two centuries, so yeah, I agree that it's a bit early to accept it into the language just yet. Let's give it another 400 years or so and see if it sticks.
I couldn’t agree more with all of the comments made about you Uncle Doug! Your channel is the best I’ve seen for really learning and understanding how tube amplifiers function. I wanted to learn how to maintain and repair my own tube amplifiers. You do a great job teaching electronic theory, tube/transistor theory, electrical and electronic circuitry. Best yet you teach how it all works together to make that Magic happen in tube amps that gives a guitar it’s voice that makes it cry and sing!!! I don’t care what the voice modeling amps salesman say. NOTHING BEATS the sound of a tube amp. They can say their modeling amps can copy the sound of all the greatest tube amps all in one amplifier until the cows come home. We all know what comes out of a cow too! B….S…. But at the end of the day it’s still just a second rate copy at best of the original genuine article. When I first started watching your channel I didn’t know jack squat about tube amps and now I am learning one video at a time. Thank you so much for making these videos!!!!! Your furry four legged friends are very cool too. One last thing, your tone generator is pretty wild. It puts out some of the best gasoline powered leaf blower simulations I’ve ever heard. LOL
Thanks, John. That's beyond my ability at the moment. I would have to get my hands on a proper Dumble amp in order to make any legitimate observations.
Learned all of this 43 years ago....but never really 'got it' until I watched this! Really appreciate your straight forward, logical approach. When I went through tech school we always got wrapped around the axle with all the math and technical jargon and the practical application kind of took a back seat. The info was there but we were more focused on passing certification exams than actually understanding how it worked in real world applications. Thanks Uncle Doug!😀😀👍👍
You have described the shortcomings of most formal education, FB. It tends to exist to provide certifications rather than genuine knowledge. It was our pleasure :)
@@UncleDoug Agreed. Spent much of my working career chasing various 'certifications'...FCC , Novell, Microsoft,Cisco, Watchguard, etc. Most were sorely lacking in practical real world application...Thanks again!
The dear old uncle from the heaven of tube knowledge and pedagogy did it again. thank you so much for making these wonderful videos. So much knowledge put in to a beautiful package of clear and precise language and no nonsence methodes. Easy to skip x-mas shopping :-)
School is in session! Great way to start the day. In the hi-fi world, when designing an amplifier, a lot of work goes into deciding where you want to 'specify' the bias point, as it sets how much Class A region ( lowest distortion) you have and how much power you can deliver, and how the idle current will effect the tube life. Take note youtube viewers, this IS meat and potatoes tech, teaching the REAL facts and how engineering choices alter the sound of an amplifier. In the hi-fi world we not only listen, we use test signals and distortion analyzers. Right now I am designing a push-pull 6BQ5 amplifier output stage. It is going to be switchable between triode and ultra linear pentode modes, and have a 2 position bias switch, allowing choice of shorter tube life lowest distortion larger Class A region, or for less Class A overlap giving longer tube life and a few more watts, at the sacrifice of slightly higher coloration.
Howdy there Uncle D.! I Have not chimed in for quite some time so I'm seizing the opportunity now. I hope you are doing well out there...you sound healthy and strong, as usual! I just wanted to thank you once again for your continual, generous sharing of your wealth of knowledge and good humor! It was apparently Destiny or Fate that I was born and/or became alcoholic...just as it was, by Design that I continue my SUPER DUPER GRATEFUL recovery from alcoholism. I am so happy to have turned into a Fully Blown Ampaholic, due in no small part to you! Thanks for helping me in my transformation in BOTH departments!!! Life has been a wonderfully wild ride for me since I found myself alive in this world and I'm so glad you have been a part of it! Three Cheers for you Uncle Doug! Long may you run! Much Love~Whiskey Tango Delta
Wow, thanks so much for your very nice comments, WTD. It's good to hear that you have moved away from a dangerous obsession and toward a creative one. Best of luck with your continued transformation.
Uncle doug your channel is just so awesome. Whenever I have a question about tube amps, you always have a video for it. And yours always has the best explanation!
This channel is keeping me awake all night. I wish all this info was out many years ago when I wanted to do this kind of work a lot more. I work on my own amps well enough but not to this depth. I can't seen to stop watching video after video. Nothing better to do anyway lol.
I thoroughly enjoy your "Technical Second Features" as you described at the tail end of the video. I actually enjoy watching all of your videos, you speak my language. Thank You for your work!!
both parts were great. i'm so impressed that you not only show that there are bias differences but that you are also open to change your mind based upon your testing. and, the differences in the circuits was very educational. thank you! i'm lucky i have a 66 deluxe reverb that everyone who plays it won't play any of my other amps!
Uncle Doug, first let me say that your videos and channel are, hands down, the best on UA-cam for this subject matter. Secondly, your voice presentation is also the very best online. After I majored in music and got multiple music degrees, I went back to college and studied Computer Science, and my favorite CS teacher; the one that kept me going strong, and always kept me hungry to arrive in class early and on the front row (wonderful memories!), was a guy that had a speaking/presentation voice almost identical to yours. Your voices “could be brothers”. That said, even at 55, I love learning new things, and I still consider myself a beginner with regard to vacuum tube electronics. I am fascinated with learning how my idols, heroes, and teachers learned what they know. I’ve always believed that what one man can do, another can learn to do if he follows the same steps. That said, if you haven’t already done so, would you mind making a video outlining your training, experience, education, and your early days of how you got started in electronics, or, if you’ve already made such a video, would you mind sharing a link to it? Thanks so much! 😊😊😊
Thanks so much for your very kind comments, Steve. I am entirely self-taught, using personal experimentation and internet resources to study tube electronics theory. I began this study about 10 or 12 years ago when I retired from teaching school (math and science)......so I am a "late bloomer". Bottom line: If I can do it, anyone can, if they apply themselves 100% to self-directed learning.
@@UncleDoug ... Thanks so much for the fast reply! So rare in these times. ... WOW! Very inspiring! This inspires me to keep trying and learning, and it makes me realize I can do it too! I’m also, coincidentally, becoming very passionate about learning “wrenching”; not just on cars, but also, especially motorcycles, with a dream of being excellent at restoring vintage motorcycles some day, and I want to learn all this stuff to also simultaneously teach my autistic son, which would be great “life skills” for him, so I also love your car videos. Would you mind sharing your favorite educational book titles (electronics and/or wrenching), and also, who are your educational/UA-cam/Internet teachers and heroes in these areas? Thanks again for all you do! 😊😊😊
@@SteveHacker hi steve, you`re right its an inspiration and education everything U,D posts you can rely on as well proven ,the thing that seems to slowly dawn as we watch and enjoy is the" intuition" unc shows in his subject in hand ! be it circuitry, spanners,, or cats! lol ,bless him, like you i`m a 2 wheel type,lifetime cyclist and motorcyclist,.👍
Hi Uncle Doug, Man did I get warm and fuzzy when I saw that silverface deluxe reverb. I am 56 and seeing your amp was one of the best flashbacks a guitar slinger could have. I realise I'm more of the pull boost era of 79 or so, but the deluxes are some of Leo's greatest accomplishments. Thanks for all you do.
Uncle Doug, great work! Im still watching and trying to learn. All of this makes sense though. Excellent job of instruction! As usual, I always glean something unusual as Im watching. At about 52 min in, I heard scratching. Like pawing in the litterbox and it reminded me of a time years ago. A woman I knew had a cat for a pet in her small home. I asked if I could use her restroom. She said yes and directed me to it. As I opened the door to the very tiny bathroom, there was a toilet and snugged up to the toilet was a litterbox. Thru the door I loudly asked if I was supposed to use the toilet or the box. And to my surprise she said, " which ever one you want. Just scoop when your done"........
Mr Doug, I'd really like to call you a master of knowledge transfer and I really think you have a gift! Your videos are great in so many aspects and they are a jewel for anybody that knows how to recognize it. Best regards and please do keep up the excellent job. With great respect, Kreso
Hi Uncle Doug, your latest video couldn’t be more timely for me. The day before this video dropped, I picked up a ‘74 SFDR with a serial number just a little lower than your amp. Can’t wait to open her up to see which circuit I have! The explanation of what each change does frequency/voltage-wise is so incredibly clear & valuable. You, sir, are literally a amp tinkerer’s Godsend! Thank you from a very grateful viewer & Patreon supporter. DB
Hi again Uncle Doug, it appears that my ‘74 SFDR is the A1172 circuit. The PT does NOT have a 6.3v CT wire (but does have factory virtual CT set up). Very odd mystery. The standby is also wired pre-reservoir caps (which I am fixing right now.) Thanks again for this invaluable circuit analysis!! I am grateful for you sir! Merry Christmas, DB
Fantastic video Uncle Doug. I think the hardest thing to show is how bias changes feel. Headroom, again etc all have impact on how the amp feels to play irrespective of how it sounds. But feel impacts sound because of how it makes or allows you to play. I find higher Bias is stiffer and lower bias spongier and more sag. It’s about finding that sweet spot of the amp. Its a crazy addictive rabbit hole.
Just this morning I was thinking "It would be great if Uncle Doug developed some new circuit tutorial videos". I checked to see what you had uploaded recently, and I see that this one is fresh out of the oven! I have suggested your tutorials to a number of folks interested in learning about tube amp circuits, and the reviews have been universally positive. They were essential to getting me started with circuit design a few years back, and I think they're the best of what's out there on the subject.
Love new Uncle Doug videos. I can never get enough of these. I go back to them all the time because there is so much info. This video is a treasure and I learned a bunch. Thank you!!
This type of video is the best educational and informative that I can remember. Your knowledge and also the level of documentation take the "class" to a level of comprehension that even a non-technical skilled person can understand. Great Job Uncle Doug!
Hello Uncle Doug & Family, A new Uncle Doug video always makes my day. Been working late nights, so, a little late viewing, when done and home, I'm tired and thinking sleep. It did sound cleaner as the PD went up, at least to me. You can't help but learn a great deal from your most excellent tutorial videos. Voltage, squared, divided by the ohm's of impedance will equal the watt's of output, as learned from you, and, John Audio Tech on UA-cam, an excellent channel well worth a view, where it is solid state chip amps, John is very knowledgeable and has a lot of good information. What a great experiment and explanations of the tests and the results. As we should know from watching you, it's all about the tone, like a sweet sounding, lower watt single ended amp. Great video. Glad your doing well. Still commenting, you know what that means, still kickin'. Wishing you and yours a Happy Year End, Christmas, if you do it, and, all the best in 2021, Cass.
It's all been said, but I hit a hurdle 50 years ago, "Temperature coefficient of resistance". I baulked and never got over it. Math meeting science, loved the science... If Uncle Doug was my teacher! So I compulsively listen and learn, even though most of the content will never be used. Thanks Doug ;)
I have watched your video and listen to your evaluation. I really heard no significant difference but if I were to make a choice I’d say 70% is the best.. thank you for your ongoing efforts to help us learn and understand amplifiers
Both portions of this video were excellent. Part 2 especially. Thanks so much for explaining the reasons why the changes were made. It's a big help in understanding these circuits. Repetition is the key to learning!
always such a pleasure to watch a man at the height of his expertise demonstrate in a kind ,organised ,and well worded challenge to amplification lore.
After watching Uncle Doug’s videos all other content pales. Thank you for making these, Uncle Doug. I feel like I learn more and more even on the 10th+ rewatch.
Now repeat everything using a compressor/limiter at various points in the signal chain and factor in tube degradation and capacitor drift and compensate for variations in wall voltage and temperature...and by the time you are done you will have PSH (permanent shift of hearing) caused rapid onset aging...Outstanding work
Another fantastic and informative video. Thank you Uncle Doug. The cat digging in the litter tray around 52-53min didn’t have the same respect for what was being produced.
@@UncleDoug I was looking at the 1172 schematic again. The coupling capacitors to V6 grids were likely increased to make up for the gain loss by changing the grid leak resistors from 1M->330k for noise. At 2 kHz a .001 has a reactance of about 8 k ohms. A .01 is about 800 ohms - actually a higher gain than the original circuit...
What an extravaganza for us ampaholics! Thumbs up for having extra technical sections in your videos. I think Fender may have taken the easy way out with the majority of the voltages marked on the schematics and didn't bother to measure/change them. As you noted the power transformer doesn't change and neither does the B+ (420V) even though the rectifier does. When they dropped the node "C" resistor down to 2.2K it raised the node "C" voltage by 50V but somehow node "D" voltage was unaffected. Presumably the transformer's 5V winding was rated 50% higher than originally needed so it can handle the 3amps for the 5U4G. One advantage of the 5U4G is that it only requires around half the plate supply resistance compared to the 5AR4/GZ34. A 5U4GB/5AS4A is lower again. I'm not a fan of Standby switches but I totally agree on placing it after the reservoir cap(s). The proviso being that the caps are rated accordingly. A GZ34 with 330V on the plates and supplying no current (Standby switch open) will put out around 465-470V, too much for those 450V ones in the long term. I feel they need to be 500V units. Thanks again for this in depth and informative video. Now watch the price of SF Deluxe Reverbs go up. All the best to you and yours from my side of the Pacific. Regards, Jeff.
all i can say is: i wish i had teacher of physics like Uncle Doug when i was young
Thanks, G58 :)
Me two.
Me too!
you mean you wish your physics teacher taught you about tube amps?? yeah, me too 😆 for real though, Uncle Doug is an excellent teacher and that's a skill in and of itself, on top of his skill with tube amps. i bet he would make an excellent lesson on literally anything on which he is well informed.
A grammar teacher would have helped more. 😂
I have learned more from @Uncle Doug about vacuum tube/valve electronics than I ever did working on my ee major. I can't thank you enough for all the work you do, sharing your invaluable knowledge.
He is a great teacher.
Thanks so much, Luke. It's really rewarding to hear that our videos are helpful.
Thanks, Jennifer. From you, it means a lot.
Exactly, again the old saying, They don't teach you this in school. I have learned more in one month of Doug videos about tube amps, than I can imagine. Very well presented with everyday English language.
Amen. I was a technician in the Air Force. I was trained in Electronic Principles twice, with years of other formal training for electronic and electrical; yet, I emerged from all that training without being able to explain how to bias something. I often marvel at my notes that I took - I recognize the hand writing, but I suppose I held that information long enough to pass a test then dumped it. And in a nuclear weapon system, the troubleshooting is very narrow and clearly defined. One must have certain certifications to troubleshoot beyond what the book says for obvious reasons. But - watching Uncle (Professor) Doug has blown the door open for me and I'm recalling things I learned ins 1984. And the best part of all: I'm having FUN! I retired a few months ago for medical reasons and dreaded it. Now, holy cow - I'm digging into this and having a blast! I should've retired sooner to do this!
ADDENDA:
1.) My use of the phrase "plate resistor" to describe the 4.7/3.3 Meg wet or dry reverb resistor is meant figuratively (i.e. to describe its function), not literally.
2.) My definition of "Clipping" was inadvertently "clipped" from the video. Here is a proper definition: Clipping is waveform distortion that occurs when amplifier output tube(s) are overdriven and forced to deliver an output voltage or current beyond their maximum capability. Clipping is highly undesirable in both SS and HiFi circuits, while it is often utilized in tube amplification to enhance guitar tone. Crossover distortion, however, sounds awful and is never desirable.
3.) Clean "headroom" is the term used to describe the maximum amount of amplifier output possible before clipping begins. Maximum RMS output power is routinely measured pre-clipping, i.e. clean headroom only.
4.) I inadvertently expressed the decibel scale as being linear instead of logarithmic, during my explanation of gain vs volume. I should have stuck with "volts" instead ;)
5.) A few viewers have commented on the audio quality during the bias comparison. Recall that this is a "recording of a recording" so any artifacts are essentially doubled.
Excellent video Uncle Douglas.
It appears from oscilloscope outputs that the crossover distortion shoulders are present at low and high amplifier output/gain.
Whereas clipping type distortion occurs when the amplifier volume is cranked past a specific level.
Can our ears pick up crossover distortion?
Cheers from down under.
Imagine the confusion at the electronic stores with lines of people asking for wet resistors. Demanding to get them, small riots breaking out. Anarchy. Society breaks down and cats take over the world
@@PetraKann Yes, indeed, Petra. Crossover distortion is quite noticeable and unpleasant.....as you can hear in the 40% audio clip.
@@rjprivate We might be better off in the long run, RJ, considering the current state of affairs.
@@PetraKann - I am pretty sure, your ears can pick up Crossover Distortion... It does not sound very pleasing - hence all the efforts to avoid it...
Doug; you have the best radio voice ever-------and your dominion of the English language is astounding. I type this before I watch the whole video.
You are so kind to say so, JG. Thanks !!!
@@UncleDoug You are right up there with the guy from Distinguished Spirits.
I hear a Gene Shepherd clone in U.D.’s voice.
Everyone out there in you tube land needs to see this.. absolutely broken down to the ground and built back up with full explanation for what you did. Then break down the differences between a 900 to 4+k fender amp . With fantastic guests commentary towards the clipping. Uncle doug busting there butts . Thank you . We all love you and wish you well . Cheers ! .
Wow.....Thanks so much, W4. So glad you liked the video :) Likewise on the good wishes.
Love me some Uncle Doug in the morning. It’s 20 degrees here in Spokane and this upload warmed me right up.
Bask in the warmth of our output tubes, Vaden :)
@@UncleDoug} g 00 gold 9
Also, yes, please continue the tech talk! I'm loving it.
Will do, GL.
Bless you Uncle Doug for sharing your wisdom with us.
I have always wondered how changing component values in the Tone Circuit effects the Tone and Frequency Response:)
You are an amazing Educator and Instructor. I am a visual learner and you have always exceeded all my expectations.
Your educational videos will be used as a historical reference archive for this generation and generations to come.
Your an honorable and humble man spreading love to all your viewers.
Great Karma in your community!!!
Wow, thanks so much, F1. We truly appreciate your very nice comments.
Thx uncle Doug . Your videos bring happiness and a light of hope lately. 2020 is the worse year so far in my life. Thank you so much. Hope you have a great day.
You're quite welcome, Ken. I don't think any of us would choose to relive this year, but hopefully 2021 will be a better one.
@@UncleDoug 👍 🎄 🍻 😎
best electronic teacher/engineer I've heard explanations spot on. I have qualification in industrial electronics all for solid state micro processors and digital I always wanted to learn about vacuum tube technology and now I have learned from the master. I am now servicing my own valve amps and building valve equaliser preamps. You do have the best voice, very therapeutic.
Thanks so much for your very nice comments, Clyde.
I'd like to add my extra upvote for the part2 of the video. I really enjoy this kind of content.
Thanks, O. Your vote is noted.....and appreciated.
I always click the thumbs up on all your videos before watching them. I have learned so much from watching these.
The amp sounded at it's best at the highest bias level tested. The bass tightened up, and the highs and mids sounded more defined. I guess I'm not too surprised by the results. The tubes were designed and engineered to run optimally around 70% plate dissipation. Anything below that did not sound great at all. I would say that 60% is even too low. I would be curious to hear what 65% sounds like. I'm also curious how it would sound at above 70% up to the point of redplating. Perhaps that test would be better done with a fresh set of tubes.
Thanks so much, Jason. I agree that the 60% to 70% range was the sweet spot. I doubt that going beyond 70% would yield any significant improvement in tone.
A great presentation as always. Hypothesis, experimentation, validation and calibration very clearly and concisely presented. Also room for the subjectivity that is real, meaningful, and at the heart of all music. Bravo!
Thanks for a very kind appraisal. Our goal was each of the criteria you mentioned.
You're a national treasure, sir. After 2 days of searching fruitlessly for any useful content to help this first-timer bias a 1972 Earth B-2000 for its 4 new 6L6WXT+ tubes, I found your videos and not only biased the amp with no problem, I can now understand simple schematics as well as how tubes actually work. I can't thank you enough.
That's great news, Robert. We're really glad the videos were helpful.
Mi estimado Uncle Doug, it is amazing the teaching skills you have, you was, if not in this life in some past, the best "Maestro" I've ever known or existed. Me quito el sombrero para saludarlo! Un fuerte abrazo desde Mexico.
Wow, thanks so much, Juan. We really appreciate your very kind words and wish you the very best :)
Dear U.D : The quality of this channel is unmatched!
Thank you so much for your generosity and willingness to share your knowledge with us.
As usual : you the man! 🤘🏼
Wow....thanks so much, Adrien. Hearing from great viewers like you makes it all worthwhile :)
If your looking for how to videos on building any kind of amplifier THIS is the right place. Congratulations on a wonderful explanation on this particular part of
practical amp design Uncle Doug. You and Mr. Paul Carlson are the best teachers when it comes to electronics design on UA-cam in my honest humble opinion!
Wow....thanks so much, HM. We really appreciate it :)
The double feature was great, Uncle Doug! Thank you for another top quality video!
My pleasure, OM.
That was excellent Uncle Doug! Thank You 👌
Glad you enjoyed it, CS :)
Thanks for the great video. Bias is so important. I always tell my friends "bring me any great amp and I can destroy its sound by a wrong bias"
Well said, RJ. You're welcome :)
i can definitely hear the goodness at 60% and 70%. Good looking DR you have there Doug! I have a Blackface DR myself and it's biased around 68% because that's what sounds good to my ears. Another excellent video sir! Many Thanks!
Agreed, Cary. The sweet spot varies but somewhere between 60% and 70% seems to give the best bang for the buck. Thanks !!!
That was an outstanding educational video that described complicated electronic principles in a way a layman can understand and it answered so many questions that Fender lovers have wondered for years...you should be proud of yourself Uncle Doug.....thank you for the knowledge...Keep up the great work!!
Thanks for your very nice comments, Jeff. We will :)
Always good to see someone dispel amplifier myths and half-truths through the application of science. Maybe next you could convince guitarists that measuring DC resistance of pickups in isolation doesn't tell them anything about the output voltage!
Thanks, Frank. I'll keep your suggestion in mind :)
I think I speak for everyone when I say we greatly appreciate you using the dummy load, Doug. I also want to echo the sentiments of the other commenters and add that as someone who only recently started to gain (pun intended) an interest in the science of amplifiers, this exhaustive test/explanation/lesson on both an objective AND subjective front, you left no stone unturned and I didn't feel as though I was expected to fully understand a litany of technical vocabulary to learn from you. The long and short of it is this: Thank you for being a great teacher!
Thanks so much for your very nice comments and observations, Peter. I'm glad the video was helpful.
This video is a classic already.
Thanks, H :)
Nothing like a Practical mind for solving problems and teaching others, and Uncle Doug, you have a great practical Mind, thanks!
Thanks so much, Rene :)
Bless you Uncle Doug for another amazing educational video. We are all locked down, so we turn off the TV and turn on Uncle Doug's inspirational videos. We want more:)
Thanks so much, F1. We are working furiously on future videos for you :)
Uncle Doug can you get me some schematics on your volt and amp meter that you put your tubes in to measure the amps and volts on the match tube.s@@UncleDoug
As someone who enjoys working on my own Fender amps but does so with enough knowledge to be dangerous, your videos help keep me out of trouble by being my first "Go-To" reference. I've learned so much from you and continue to learn something new with every video you post. Many thanks for sharing your knowledge, experience, and insights - it's a great privilege to be in your virtual classroom. And your 4 legged teaching assistants help make these even better! Bravo, and many thanks, Uncle Doug!
You're quite welcome, Russell. We're glad you find the videos to be helpful.
OK, who's the yutz that gave this a thumbs down. There's one in every crowd I guess.
Perhaps it was a leper whose nose detached from his face while coincidentally over the thumbs down key ;)
3 now , it’s a beak fest of epic proportions:(
@@v12dot maybe they're just biased against this video for some reason
They saw "Headroom" and thought it was porn.
I don't know who thumbs down any uncle doug videos but there are some real spiteful people in the guitar/amp tech world
I love when you go through schematics and explain in detail what is going on, etc. This is what makes your channel so so so special, your ability to teach in a very direct and understandable way, show us what is happening in the amps physically and then show us again on paper. Very comprehensive. I LOVE YOUR TECHNICAL VIDEOS TO DEATH.
Wow.....thanks so much, Sean. I'm glad the videos are clear and enjoyable.
Doug, this is one of your best presentations yet. I learned a lot from this one, thank you!
Thanks so much. I really tried to make this a good one, and I appreciate your kind words.
Thank you Uncle Doug. You made sense out of the hours of videos with conflicting information and over or under technical detail and just plain nonsense that i have endured trying to learn the skill of tube amp biasing. This is the last video i need to watch on the subject, i wish it had been the first. Thank you Sir.
You're welcome, DS. We're glad you enjoyed it.
I definitely think the 40% sounded clippy but above 50% it started to clean up. IMO 70% sounds best, maybe that's why that's they suggested 70%.
Agreed, Tim. The 70% recommendation does seem to be the best. Now we can actually understand why.
Cross over distortion is very audible
have I missed the link to the actual recording used for the test? :-/
Hi from England...heard about Uncle Doug's" valve channel" only this evening from a friend.We both have a collection of valve "babies",Fender blues juniors,Vox AC15's,Peavey delta Blues,and right back to a 1958 Watkins dominator...I am amazed at the wealth of information that is available here...an absolute gold mine for us" tone hounds"....and delivered with an authority and conviction that is easily absorbed,even if you don't have a major in electronics ..thanks Uncle Doug,keep them coming....and Stay Safe.......Dave ..midnight and still watching!
Welcome to our channel, Dave. All "Tone Hounds" are welcome :) Have a great holiday season.
Unless your dream amp (circuit) already exists, or you’ve already built it, I’d like to see you build one. All the bells and whistles.
I’ve seen about 90% of your videos now. Going into reruns to reinforce what I’ve learned. I bought a late 50’s Stromberg Carlson AU57 PA amp and had the schematic blown up to blueprint size. It has 4 inputs, 5 12AX7’s, 2 6L6G’s, 2 12AU7’s, a 5U4GB, and a 6X4. I’m not sure if I’m going to restore it or turn it into something else at this point. Should be an interesting winter project.
Thanks, FT. I think a Princeton Reverb is pretty close to my ideal circuit.....great tone and effects but not too bulky. Good luck with your project.
I love your technical videos. I am almost confident enough to tackle an amp build myself because of how well you explain things. I’ve gone back and watched all of your old tutorial videos multiple times.
That's great to hear, Michael. It makes it all worthwhile for us.
Kids should listen to your channel just to learn how to speak English.
Thanks, Eric :)
Yes Doug, you need far more LIKES, you knows, init's then children will also understand you!!
@@mrman3565 The first recorded use of 'kid' as a colloquial term for 'human child' was in the 16th century. By the time Charles Dickens used it in 'Oliver Twist' it had been in use for over two centuries, so yeah, I agree that it's a bit early to accept it into the language just yet. Let's give it another 400 years or so and see if it sticks.
@@circusbrains Yes, indeed, CB. I was a classroom Math & Science teacher for many years.
@@frmcf Well said, McF :)
I couldn’t agree more with all of the comments made about you Uncle Doug! Your channel is the best I’ve seen for really learning and understanding how tube amplifiers function.
I wanted to learn how to maintain and repair my own tube amplifiers. You do a great job teaching electronic theory, tube/transistor theory, electrical and electronic circuitry. Best yet you teach how it all works together to make that Magic happen in tube amps that gives a guitar it’s voice that makes it cry and sing!!!
I don’t care what the voice modeling amps salesman say. NOTHING BEATS the sound of a tube amp. They can say their modeling amps can copy the sound of all the greatest tube amps all in one amplifier until the cows come home. We all know what comes out of a cow too! B….S…. But at the end of the day it’s still just a second rate copy at best of the original genuine article.
When I first started watching your channel I didn’t know jack squat about tube amps and now I am learning one video at a time. Thank you so much for making these videos!!!!! Your furry four legged friends are very cool too. One last thing, your tone generator is pretty wild. It puts out some of the best gasoline powered leaf blower simulations I’ve ever heard. LOL
Thanks for all the great comments, Jeff :)
@@UncleDoug You’re welcome and thank you!
Excellent presentation as usual Uncle Doug, could you expose the Dumble myth as a fact or fiction?!
Thanks, John. That's beyond my ability at the moment. I would have to get my hands on a proper Dumble amp in order to make any legitimate observations.
Learned all of this 43 years ago....but never really 'got it' until I watched this! Really appreciate your straight forward, logical approach. When I went through tech school we always got wrapped around the axle with all the math and technical jargon and the practical application kind of took a back seat. The info was there but we were more focused on passing certification exams than actually understanding how it worked in real world applications. Thanks Uncle Doug!😀😀👍👍
You have described the shortcomings of most formal education, FB. It tends to exist to provide certifications rather than genuine knowledge. It was our pleasure :)
@@UncleDoug Agreed. Spent much of my working career chasing various 'certifications'...FCC , Novell, Microsoft,Cisco, Watchguard, etc.
Most were sorely lacking in practical real world application...Thanks again!
I'm thinking 65% dissipation may sound best. Might EL34s be different than 6V6s when it comes to optimal tone?
It's a personal preference, John, and yes, I think different tubes respond differently to bias levels.
The dear old uncle from the heaven of tube knowledge and pedagogy did it again. thank you so much for making these wonderful videos. So much knowledge put in to a beautiful package of clear and precise language and no nonsence methodes. Easy to skip x-mas shopping :-)
Thanks so much for your very kind words, Jan. We really appreciate them :)
School is in session! Great way to start the day. In the hi-fi world, when designing an amplifier, a lot of work goes into deciding where you want to 'specify' the bias point, as it sets how much Class A region ( lowest distortion) you have and how much power you can deliver, and how the idle current will effect the tube life. Take note youtube viewers, this IS meat and potatoes tech, teaching the REAL facts and how engineering choices alter the sound of an amplifier. In the hi-fi world we not only listen, we use test signals and distortion analyzers. Right now I am designing a push-pull 6BQ5 amplifier output stage. It is going to be switchable between triode and ultra linear pentode modes, and have a 2 position bias switch, allowing choice of shorter tube life lowest distortion larger Class A region, or for less Class A overlap giving longer tube life and a few more watts, at the sacrifice of slightly higher coloration.
Thanks so much for your very knowledgeable and informative input, Jennifer.
Howdy there Uncle D.! I Have not chimed in for quite some time so I'm seizing the opportunity now. I hope you are doing well out there...you sound healthy and strong, as usual! I just wanted to thank you once again for your continual, generous sharing of your wealth of knowledge and good humor! It was apparently Destiny or Fate that I was born and/or became alcoholic...just as it was, by Design that I continue my SUPER DUPER GRATEFUL recovery from alcoholism. I am so happy to have turned into a Fully Blown Ampaholic, due in no small part to you! Thanks for helping me in my transformation in BOTH departments!!! Life has been a wonderfully wild ride for me since I found myself alive in this world and I'm so glad you have been a part of it! Three Cheers for you Uncle Doug! Long may you run! Much Love~Whiskey Tango Delta
Wow, thanks so much for your very nice comments, WTD. It's good to hear that you have moved away from a dangerous obsession and toward a creative one. Best of luck with your continued transformation.
Every Video from Uncle Doug is "Classroom in Session"
Thanks, Shyam. I hope the "classes" are enjoyable :)
Wonderful experiment, Uncle Doug. Just the facts. You’re a treasure.
Thanks, Ryan :)
hearing trouble with the spectrum, as if pieces of the sound get eaten~
The interface and the daw may be clocked differently.
Yes, that happens a lot ;)
Like others have said, I learn more here than all the study materials available period. Thanks Doug for your detailed information and resources.
You're welcome, Larry. I'm glad the videos are helpful.
little hair on the peach at higher volumes~
Uncle doug your channel is just so awesome. Whenever I have a question about tube amps, you always have a video for it. And yours always has the best explanation!
Thanks, Daniel. We're glad you enjoy our vids :)
Please keep 'em coming. I cannot believe how much more, I now understand, how amps work ! ! !
Your method of teaching is off the charts awesome.
Thanks, Richard. Will do :)
This channel is keeping me awake all night.
I wish all this info was out many years ago when I wanted to do this kind of work a lot more.
I work on my own amps well enough but not to this depth.
I can't seen to stop watching video after video.
Nothing better to do anyway lol.
We're glad you find the videos addictive and helpful, Jerry :)
I thoroughly enjoy your "Technical Second Features" as you described at the tail end of the video. I actually enjoy watching all of your videos, you speak my language. Thank You for your work!!
You're welcome, Steve.
both parts were great. i'm so impressed that you not only show that there are bias differences but that you are also open to change your mind based upon your testing. and, the differences in the circuits was very educational. thank you!
i'm lucky i have a 66 deluxe reverb that everyone who plays it won't play any of my other amps!
Thanks so much, Michael. I appreciate your kind and accurate comments. You are a lucky guy to have such a great amp.
Uncle Doug, first let me say that your videos and channel are, hands down, the best on UA-cam for this subject matter. Secondly, your voice presentation is also the very best online. After I majored in music and got multiple music degrees, I went back to college and studied Computer Science, and my favorite CS teacher; the one that kept me going strong, and always kept me hungry to arrive in class early and on the front row (wonderful memories!), was a guy that had a speaking/presentation voice almost identical to yours. Your voices “could be brothers”. That said, even at 55, I love learning new things, and I still consider myself a beginner with regard to vacuum tube electronics. I am fascinated with learning how my idols, heroes, and teachers learned what they know. I’ve always believed that what one man can do, another can learn to do if he follows the same steps. That said, if you haven’t already done so, would you mind making a video outlining your training, experience, education, and your early days of how you got started in electronics, or, if you’ve already made such a video, would you mind sharing a link to it? Thanks so much! 😊😊😊
Thanks so much for your very kind comments, Steve. I am entirely self-taught, using personal experimentation and internet resources to study tube electronics theory. I began this study about 10 or 12 years ago when I retired from teaching school (math and science)......so I am a "late bloomer". Bottom line: If I can do it, anyone can, if they apply themselves 100% to self-directed learning.
@@UncleDoug ... Thanks so much for the fast reply! So rare in these times. ... WOW! Very inspiring! This inspires me to keep trying and learning, and it makes me realize I can do it too! I’m also, coincidentally, becoming very passionate about learning “wrenching”; not just on cars, but also, especially motorcycles, with a dream of being excellent at restoring vintage motorcycles some day, and I want to learn all this stuff to also simultaneously teach my autistic son, which would be great “life skills” for him, so I also love your car videos. Would you mind sharing your favorite educational book titles (electronics and/or wrenching), and also, who are your educational/UA-cam/Internet teachers and heroes in these areas? Thanks again for all you do! 😊😊😊
@@SteveHacker hi steve, you`re right its an inspiration and education
everything U,D posts you can rely on as well proven ,the thing that
seems to slowly dawn as we watch and enjoy is the" intuition" unc shows
in his subject in hand ! be it circuitry, spanners,, or cats! lol ,bless him,
like you i`m a 2 wheel type,lifetime cyclist and motorcyclist,.👍
The sound gets progressively fuller, in the bass and the highs, as I hear it. Thanks for this informative demonstration!
I agree with your analysis, Oleg. Thanks !!
Hi Uncle Doug,
Man did I get warm and fuzzy when I saw that silverface deluxe reverb. I am 56 and seeing your amp was one of the best flashbacks a guitar slinger could have. I realise I'm more of the pull boost era of 79 or so, but the deluxes are some of Leo's greatest accomplishments. Thanks for all you do.
You're welcome, Phil. I agree :)
Uncle Doug, great work! Im still watching and trying to learn. All of this makes sense though. Excellent job of instruction! As usual, I always glean something unusual as Im watching. At about 52 min in, I heard scratching. Like pawing in the litterbox and it reminded me of a time years ago. A woman I knew had a cat for a pet in her small home. I asked if I could use her restroom. She said yes and directed me to it. As I opened the door to the very tiny bathroom, there was a toilet and snugged up to the toilet was a litterbox. Thru the door I loudly asked if I was supposed to use the toilet or the box. And to my surprise she said, " which ever one you want. Just scoop when your done"........
Thanks, Wayne. Yes, that was KC in the catbox. You should have married that woman......her accommodating attitude is hard to find :)
Thank you Uncle Doug. I totally understand what you explained. A true professional teacher. Good on you Sir.
You're quite welcome, Ken. Glad you enjoyed it.
Mr Doug, I'd really like to call you a master of knowledge transfer and I really think you have a gift!
Your videos are great in so many aspects and they are a jewel for anybody that knows how to recognize it.
Best regards and please do keep up the excellent job.
With great respect,
Kreso
Wow, thanks so much, Kreso. We will :)
Hi Uncle Doug, your latest video couldn’t be more timely for me. The day before this video dropped, I picked up a ‘74 SFDR with a serial number just a little lower than your amp. Can’t wait to open her up to see which circuit I have! The explanation of what each change does frequency/voltage-wise is so incredibly clear & valuable. You, sir, are literally a amp tinkerer’s Godsend! Thank you from a very grateful viewer & Patreon supporter. DB
That's great news, DB. I'm glad the video was helpful and wish you the best with your investigation.
Hi again Uncle Doug, it appears that my ‘74 SFDR is the A1172 circuit. The PT does NOT have a 6.3v CT wire (but does have factory virtual CT set up). Very odd mystery. The standby is also wired pre-reservoir caps (which I am fixing right now.) Thanks again for this invaluable circuit analysis!! I am grateful for you sir! Merry Christmas, DB
Fantastic video Uncle Doug. I think the hardest thing to show is how bias changes feel. Headroom, again etc all have impact on how the amp feels to play irrespective of how it sounds. But feel impacts sound because of how it makes or allows you to play. I find higher Bias is stiffer and lower bias spongier and more sag. It’s about finding that sweet spot of the amp. Its a crazy addictive rabbit hole.
Thanks, Joe. Very well stated......I agree completely.
Just this morning I was thinking "It would be great if Uncle Doug developed some new circuit tutorial videos". I checked to see what you had uploaded recently, and I see that this one is fresh out of the oven! I have suggested your tutorials to a number of folks interested in learning about tube amp circuits, and the reviews have been universally positive. They were essential to getting me started with circuit design a few years back, and I think they're the best of what's out there on the subject.
Thanks so much, Tom. I'm glad you enjoy them. Next will be a BF/SF comparison of the Super Reverb.
Love new Uncle Doug videos. I can never get enough of these. I go back to them all the time because there is so much info. This video is a treasure and I learned a bunch. Thank you!!
You're quite welcome, Mp. I'm glad you enjoyed it :)
The explanation of the phase inverter section is the best I ever heard.
Thanks, C58 :)
Very interesting and informative video. Great job Uncle Doug, Thank you for going the extra mile.
You're welcome, Jeff.
Thanks for another great vid uncle doug! Youve been teaching me about amp science since i was an 8th grader and im 20 now!
You're welcome, LF. You're making me feel old ;)
This type of video is the best educational and informative that I can remember. Your knowledge and also the level of documentation take the "class" to a level of comprehension that even a non-technical skilled person can understand. Great Job Uncle Doug!
Thanks so much, Juan. I sincerely appreciate your kind words and am glad you enjoyed the video.
Hello Uncle Doug & Family, A new Uncle Doug video always makes my day. Been working late nights, so, a little late viewing, when done and home, I'm tired and thinking sleep. It did sound cleaner as the PD went up, at least to me. You can't help but learn a great deal from your most excellent tutorial videos. Voltage, squared, divided by the ohm's of impedance will equal the watt's of output, as learned from you, and, John Audio Tech on UA-cam, an excellent channel well worth a view, where it is solid state chip amps, John is very knowledgeable and has a lot of good information. What a great experiment and explanations of the tests and the results. As we should know from watching you, it's all about the tone, like a sweet sounding, lower watt single ended amp. Great video. Glad your doing well. Still commenting, you know what that means, still kickin'. Wishing you and yours a Happy Year End, Christmas, if you do it, and, all the best in 2021, Cass.
Thanks so much, Cass. Likewise to your and yours for a great Christmas.
To me 60% biasing sounded more free of distortion !🥰!
Thanks for your input, Ana.
Such a great class of audio, tubes and electric math! Thanks for sharing so much! 👏👏👏👏
Glad you enjoyed it, Gustavo.
It's all been said, but I hit a hurdle 50 years ago, "Temperature coefficient of resistance". I baulked and never got over it. Math meeting science, loved the science... If Uncle Doug was my teacher! So I compulsively listen and learn, even though most of the content will never be used. Thanks Doug ;)
You're welcome, Garry. Thanks for watching :)
I keep thinking, "this is the BEST video from Uncle Doug" and then finding a better one. BUT.....this might be.....
Wow....thanks, Stewart :)
Thank you Uncle Doug, I really Appreciate you going into such detail, I'm leaning everyday from your videos.
That's good to hear, GA.
Another excellent tutorial on Bias and circuit changes from Blackface to Silverface! Thanks, Uncle Doug.
You're welcome, T. Glad you liked it :)
Uncle Doug, I like your expertise and enjoy your humour...keep on Sir
Thanks, Nino. Will do :)
This presentation is outstanding! Yes, please continue such subjects.
Thanks, Patrick. Will do :)
This is a really intelligent in-depth tutorial. Thank you
Glad you enjoyed it, C.
Uncle Doug, you are quite an amazing Educator.
Thanks, Jami :)
Yes, please continue the tech talk! It is super!!
Thanks, Antonio. Will do.
This video is one of the most useful videos on UA-cam regarding this subject.
Thank you SO MUCH for doing this, and clearing this up. You're awesome!
Wow, thank you, DW :)
Glad I save this stuff for reference later. This is gold to me. Thank you Uncle Doug!
Glad to hear it, 69M :)
Excellent topic with a peerless presentation. Thanks again Uncle Dave and et. al.
Thanks so much, Frank. Glad you enjoyed it.
Uncle Doug is a National Treasure and true American 🇺🇸 thank you so much for teaching us
Thanks so much, Jim :)
I have watched your video and listen to your evaluation. I really heard no significant difference but if I were to make a choice I’d say 70% is the best.. thank you for your ongoing efforts to help us learn and understand amplifiers
You're welcome, SD. Thanks for your input.
We appreciate everything you do.long live uncle doug and dlab.
Thanks, Eric :)
Fully agree! I would like to add El Paso tube amps to the list as well.
Both portions of this video were excellent. Part 2 especially. Thanks so much for explaining the reasons why the changes were made. It's a big help in understanding these circuits. Repetition is the key to learning!
Thanks, ZS. Glad you enjoyed the video.
always such a pleasure to watch a man at the height of his expertise demonstrate in a kind ,organised ,and well worded challenge to amplification lore.
Wow, thanks so much, GL :)
Very well explained! I enjoyed both parts! Yes, please continue the schematic comparisons! God bless and stay healthy!
Thanks, Bruce. Will do.
Loved the science on the Tube Bias, and the circuit change info. Thanks Uncle Doug!!
You're quite welcome, Russell.
After watching Uncle Doug’s videos all other content pales. Thank you for making these, Uncle Doug. I feel like I learn more and more even on the 10th+ rewatch.
Wow.....thanks so much, Stoney.
Now repeat everything using a compressor/limiter at various points in the signal chain and factor in tube degradation and capacitor drift and compensate for variations in wall voltage and temperature...and by the time you are done you will have PSH (permanent shift of hearing) caused rapid onset aging...Outstanding work
Thanks, Paul :)
Another fantastic and informative video. Thank you Uncle Doug. The cat digging in the litter tray around 52-53min didn’t have the same respect for what was being produced.
Thanks, Stewart. Cats seem to have little respect for anything they can't eat.....or bury ;)
Better than theatre Doug. There’s always something for us to learn or view from a fresh angle. Thank you lad!
You're welcome, Byron. Glad you enjoyed the new vid.
@@UncleDoug I was looking at the 1172 schematic again. The coupling capacitors to V6 grids were likely increased to make up for the gain loss by changing the grid leak resistors from 1M->330k for noise. At 2 kHz a .001 has a reactance of about 8 k ohms. A .01 is about 800 ohms - actually a higher gain than the original circuit...
I know so little about electronics..... thank you for clearly explaining the difference between the deluxe reverb amps over the years
We're glad the videos are helpful, Jim.
I agree, the tone was better to me as it increased and 70% was the best. Thanks for this public service.
You're welcome, Will. Glad you enjoyed the video.
What an extravaganza for us ampaholics! Thumbs up for having extra technical sections in your videos. I think Fender may have taken the easy way out with the majority of the voltages marked on the schematics and didn't bother to measure/change them. As you noted the power transformer doesn't change and neither does the B+ (420V) even though the rectifier does. When they dropped the node "C" resistor down to 2.2K it raised the node "C" voltage by 50V but somehow node "D" voltage was unaffected. Presumably the transformer's 5V winding was rated 50% higher than originally needed so it can handle the 3amps for the 5U4G. One advantage of the 5U4G is that it only requires around half the plate supply resistance compared to the 5AR4/GZ34. A 5U4GB/5AS4A is lower again. I'm not a fan of Standby switches but I totally agree on placing it after the reservoir cap(s). The proviso being that the caps are rated accordingly. A GZ34 with 330V on the plates and supplying no current (Standby switch open) will put out around 465-470V, too much for those 450V ones in the long term. I feel they need to be 500V units. Thanks again for this in depth and informative video. Now watch the price of SF Deluxe Reverbs go up. All the best to you and yours from my side of the Pacific. Regards, Jeff.
Thanks so much for your very accurate, informative input, Jeff. I guess the time to buy a SF Deluxe Reverb was about a week ago :)
dang it! here im thinking the price of BFs will come down after this. silly me.
Nice work here Doug, I see from the overwhelming positive comments here that you hit a tonal home run with this one. Thanks from Colorado.
Thanks so much, Craig. I hope you and your family have a great (and healthy) Christmas season.
@@UncleDoug Thanks Doug, we're doing ok, just a little stir crazy like everyone else.
i have to commend you highly for the time and effort taken to make this very informative and educational video.
Thanks so much, Mike. Glad you enjoyed it
uncle doug best wishes from argentina, you rocks, i learn a lot from your channel, tnks
Greetings to my Argentinian pal, Mauro. Thanks for watching :)