EPIC Guitar Amp Conversion - Complete Tube Amp Redesign
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- Опубліковано 28 вер 2024
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In this video, we'll follow an EPIC guitar amp conversion of a 1940 Knight 35 Watt Tube PA Amplifier. This conversion stretched over the course of months and got set aside for various reasons, but it's finally finished. The main features of this amp are the push-pull 6L6G output with transformer phase inverter driven by a 6F6, and a cool and unusual Type 83 rectifier tube which contains mercury vapor. When it came to me, it had all the original tubes, but the wiring was DREADFUL, and ended up needing much more work than I had anticipated. In fact, this one would end up requiring an almost complete redesign and rebuild. I would borrow 6SJ7 preamp ideas from a 1950s Fender Tweed Champ and a 1950s Gibson GA75.
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#guitar #electronics #restoration
NOTE: As some have pointed out, the demo portion left a lot to be desired, and I agree. I didn't bother dragging out my mixer and mics on this one and used the internal mic on the Sony camera, which I'm finding out is passable for speech and some low volume music and sounds, but can tend to emphasize mids and certain unpleasant frequencies too much, especially in LOUD amps like this one. I'll probably film another demo of this thing properly and put it on Channel 2, because it really does sound fantastic in person, I just gotta capture it better..
What a unique circuit and amp.Great sounds , after all that work. Bet you have got at least 30 hrs.in it. That's $2,250 if you charge just for labor,not including parts . Wow,but look at what your getting ,one off custom built amp. If you look at small 20 watt amps like the Friedman Amo there priced at $1499 or so. So your getting a higher watt amp at reasonable price.Good work if you can get it . Have a great week.🎸👍
Great looking and sounding amp. Very creative rework! What happened with the overheating feedback resistor?
is the Sony camera the root cause of the sketchy audio at the start of the video too? The voice audio sounds clipped but not all the time, could be a repair video maybe?
Don't the Mercury Vapor tubes emit x-rays?
Wow. Sounds great despite the mic clipping and over loads. Would love to hear a better recording. That amp sounds like it could be quite the amazing little beast.
Hey man, I almost can't keep up with all of this new content. Rock on!
Hello Sir, I am one of many of your extremely happy subscribers and wanted to tell you of how Incredibly Professional you are of your work. You're an Awesome Dude! I will continue to watch your Great work and Content! Please do not allow them negative trolls get on your nerves. Please take care and keep up your Awesome work! Many thumbs up!
So nice of you
Super cool amp. Uncle Doug said you need to add a swampy tremolo circuit and hook it up to that meter.
The meter is hooked up to the output. It actually works, I just didn't film it working.
Beautiful job Brad, but I wouldn't expect anything else man.
Thanks Ron.
@@TheGuitologist Great work. I remember in the beginning of the video you had said the cost and time of the build far outweighs what you were compensated and it was no longer worth taking in outside work. I for one would love to see more work like this. If your going to custom design an amp from scratch essentially from a pile of old parts shouldn't you charge for it? I think so. Your providing a Botique service, a Botique amp build. I would imagine charging someone around $1800 for this build plus parts would be reasonable. They may not want to pay that but there would be justification for this charge. With all your research before you even pick up a soldering Iron.
@@@chrislangdell117 Absolutely agree Chris. I thought $1000 but yeah! Brad deserves it. The guy should ask Brad nicely if he would sign it for him & put a guitologist sticker on it!
Well cool man, patience and dexterity in abundance and a bog load of skill. Very enjoyable 🙂
Loved your redesign and I'd like to say you are an artist to be able to draw a schematic like you do. You made it fit exactly on one page of your graph paper. Everything is in perfect proportion. Amazing.
Never seen you do that before very nice work that was a hell of a cleanup
The first thought I got from the sound of the amp was George Thorogood’s House Rent Blues. Great break up that screams the blues. Great video Brad!
Dedicated and skilled - a deadly combination. Despite not having a clue about 99% of what you did here, I can still admire the effort and the result. Nice one!
Excellent video. Nice meter. Great night light. You must add a small meter circuit. Seeing that bounce would be Awesome!
Thanks.
Absolutely Correct! That would be the icing on the cake for sure.
The meter works perfectly. Bounces with the guitar. I just got lazy and didn't film any b-roll of the bounce while playing. I was rushing to finish the video and get it published and forgot to do that.
Nice Beaver!
Thanks, I just had it stuffed.
@@TheGuitologist Who knew that dry Beavers from the 1940's still worked so well...
Another fantastic video Brad. You are right up there with Uncle Doug when you do work like this and I know you consider him to be a real renaissance man. I thourghly enjoyed this, Thanks and best wishes.
Brad, wonderful job! That thing is a Beast dripping with evil goodness!
That amp is so sweet!
Brad, you're an artisan and an archeologist in your own right. Digging through these broken and shattered cathedrals of sound and eventually rebuilding those towards a new glory.
That's gotta be one of the coolest looking (now) guitar amps to exist
Good to see you back on the tools
Hi Brad - so I noticed that this amp has coke bottle tubes in it. I also noticed that you had quite a few boxes of new tubes on the bench and some used tubes on the bench that caught my eye. I noticed you had some used PFPTT tubes (Pink Floyd Psychadelic Tone Tubes), which are also known generically as "prescription bottle tubes with built in safety caps". Pink Floyd really knew how to make use of these tubes to create some serious psychedelic tones. ;-)
I appreciate and admireyour dedication to preserving as much as you could. I recently found a series filament style stereo amplifier, a pair of 50L6 GT's and 7025's. It was basically laying outside in the Florida weather, only shielded from the rain by an old RV. The dirt and god knows what else was so thick inside the chassis you could barely see the chassis and tube sockets inside. It was just the amplifier itself, no name or indication what it came from. On top of that it looked like it had experienced a catastrophic failure at some point and had been hacked with bad repairs and all kinds of stuff was disconnected, like someone had attempted to fix it not knowing what they were doing and simply chucked it outside. I had no schematic and no hope of tracing what was there and restoring it so sadly i jusy had to gut it and save what i could. I'd like to make something of it that at least cosmetically resembles what it once was, maybe find a way to use the same compliment of tubes although that might be more effort than its worth. It's a bit of a ship of Theseus situation but even if it could be restored it'd be the same i suppose due to how bad off it was. I'd like to try to take inspiration from weird and unique old amps like Ampeg's, Valco, Sunn, things like that. Not just a fender or Marshall copy or something thats common and just sounds like everything else as you mentioned. Apologies for the long winded comment, i appreciate your content so much. I've learned a massive amount from your channel and you inspired me to learn to fix things myself when most people my age just throw it away and buy the newest thing. Thank you sir 🙏
I fell asleep a ways in and woke up to the playing at the end. Now that is a good sounding amp.
THIS is the killer content!
Hey man, people don’t understand how much work research..it takes. Brad.great job
BEST Film Yet, a full length feature!
Glad you dug this one. It was a ton of work making it.
Very nice deep dive into what it takes to do a custom like this killer! If you do one again, do an auction with min bid. Put your brand on it and see what happens. You might be surprised.
"Gee whiz Ward! You were a little hard on the Beaver last night."
Keep em glowing!
This is the old Brad we know and want to see. Hope all your problems solved or will solve soon. Keep on posting videos like this! Great guitarplay also. Greetings from Germany
Another cool video! You're on fire!
Sweet sounding amp!!!
"When you don't know what the fuck you're doin' " Brad learns and teaches.
Thanx man
Good Job converting the 70 volt public address amp. The odd jack was to mute the background music when making announcements. The announcement microphones were probably telephone type handsets.
Dude.... Brad..... I'm sure almost all of us know how Fugazi this project is.
No worries, take your time. We appreciate you letting us watch.
Thanks.
Thanks for understanding.
@ moonboogie N8 - I'm curious about "Fugazi" here. It can mean "effed up," can be (New York or New Jersey) Italian for "fake," and it also means "messed up." I'm guessing "messed up" here due to the original design? Thumbs up!
@@bobvines00 its fubar
@@michaelcandido2824 fixed up beyond all recognition 😆 no joke, i had a DBA registered as that a few years ago back and i still get mail addressed to FUBAR remodeling
WELCOME BACK BRAD 🎩🕶
Great video brad as usual we all appreciate the time you put in to let us look over your shoulder
This is a master class on tube amps!!! wow!
It looks and sounds good now that it's done, but the "before" views make me think that this was the kind of rig that Leo Fender looked at and said "this is awful, I know I can do better than that".
And of course, he did. Your layouts and lead dress look great, and even though the sound quality is less than stellar, I can tell that it sounds mighty good.
Definitely one of a kind.
Looks like you did it again......Nice!
Brad that amp is insain . One of the best sounds I've heard so far .. that head is a true jewel to have .it just rings like a bell . Wow man !!!
Thanks for all the inspiration Brad you and Doug are helping me get this all happening and having a lot of fun learning to build amps.
Good day Brad. Had a thought regarding the stuck knob on the pot, have you tried Kroil brand penetrating oil. This stuff can really get into every nook. Just a thought, it works wonders on stuck nuts/bolts in mechanical work and can be used very sparingly if you allow it time to creep down into whatever you've applied it to. I'm a lifelong mechanic/welder and have little knowledge or skills with electronics and I must say you've really opened my eyes to the subject. I love the conversions, and I almost pulled the trigger on a Laffiette pa amplifier I saw on eBay and a free Hammond organ I saw on craigslist. I imagine one day soon I'll give it a go, and hopefully don't blow it up. Take care dude, love the channel.
That amp sounds awesome! I seem to hear a hint of a natural brown tone.
Man what a project on this one Brad. Always fun to follow along with ya on these. btw, you reminded me of the time being the Peruvian village of Los Frijoles Perdidos and listening to the Howling Monks of Monte Tonto. Good times man.
I bet that was amazing.
Bad ass project man can't wait to see it work
that last little lead run,damned that was sweet maybe at 1:23 or slightly after
You have excelled yourself, B. Thank you, once again. I'll try soon to send you a wee something from my State Pension ... But please never forget ... I, like you, will forever be *Twenny-One!* Stay free. R 🎯
just discovered your channel on YT.., l like your style ., you're not full of shit , you hand deliver it with no postage due and I dig that refreshingly...., thanks
To get the knob off you could have used a needle tip bottle to feed the back side of the knob some rubbing alcohol, that is how I remove lots of different adhesives I have even undone probably five bottles worth of krazy glue (not really that much but a good bit that was on a guitar pick guard's controls... just sharing some tactics my dude. You do great work and I like your commentary.
Wooo this amp looks and sounds so fkn great plus the secret sause in the power rectifier
Good job Brad! Time to go out and break some stuff after that epic struggle!
This was a hell of a conversion. I just acquired a 1946 Operadio 115 watt PA head that I want to convert. Similar set up but no bunched up wires and components...it’s all point to point wiring. Two 6L6GC’s and a giant mysterious lightbulb tube, and three very weird preamp tubes with wires connected at the tops.
If only I knew of a competent tech that could make this 115 watt monster into a guitar amp...(hint hint, Brad lol).
I know this was a pain in the ass, but I would love to see this conversion happen, and I’m sure it would make great content...GUITOLOGIST please help!!!
Amazing amp. I prefer the first channel. I agree with you this is something different very rich in harmonic. You should post a more Hifi of this demo not everybody are ready to listen a 1.25h amp video like me haha. Sound killer. Keep rocking!
The end result was very cool sounding. I now expect to see Marshall add that stool design to their lifestyle brand.
Sounds great!
nice job
Great job bringing that piece of history back to life and giving it a new purpose, Brad. There is indeed a lot of work that goes into making something like that happen and present the process to your audience, and I definitely appreciate the effort.
Question: I have a Hammond AO-50 amp that I salvaged from a Hammond-Everett organ. I want to make it a guitar amp. I have paid attention to you, Uncle Doug, D-Lab, and Mr. Carlson in how to do so, and I HAVE learned a lot so far, but I still don't feel confident enough to do it myself. I've studied some books and other material but I end up second guessing myself when it comes to digging in. Any suggestions?
Yeah, just do it. Thinking should only be a precursor to doing.
@@TheGuitologist Well then, off to the races. Wish me luck. :D
I have a similar amp, an ancient institutional PA amp that I got from the Emile Berliner Museum of Sound Waves in Montreal. I showed it to my amp tech; he said he could convert it, if I could afford to support him and his family for a year or two. It was even more of a dog's breakfast inside than this Knight. So now I own a cool old black box with five bright red chicken head knobs, and no practical value.
@34:46 - to quote Mel Brooks as "Yogurt" in the movie Spaceballs - "Merchandising Merchandising. We put the pictures name on EVERYTHING"
I think I had rather start from scratch than rebuild a project like this.
Try using 'mixer resistors' from the wipers of those two volume pots. You'll get less interaction. Basically the same way that many Fender and Marshall amps use a 270k-470k resistor in series with the volume pot wiper, which then join together to 'mix' the signals.
I have an amp that's true point to point wiring. It looks like a metal spider spun a web in the chassis. If something ever goes wrong with that amp, it's going directly on a shelf as a piece of art, and will never move again.
The wires look like they have withstood the the torture test of time.
Absolutely Incredible Madman...
This is the second amp I've seen using a 6SA7 pentagrid converter in one of it's stages. That's a very strange tube to use in an amplifier. It's basically two pentodes stacked on top of one another with one plate and cathode. It was designed to replace two tubes in superheterodyne radio receivers and improve the performance at the same time. In the usual application the bottom set of grids are used as an oscillator which directly modulates the electron beam coming off of the cathode, and the top set of grids acts as a mixer, mixing an input signal with the output of the oscillator before the resulting signal is taken off at the plate.
I have one of those component testers, what I did for test leads is I made a pair of banana jack sockets connected to pins, so I can just plug in standard multimeter probes, tweezer probes or clip leads. I was gonna try fit them into the case but I don't know if that'll work too well.
Sounds amazing
Hi , new to this chat arena but been a huge fan of you Brad. You always take the time to explain the assessment all the way to the result , anyway.
I will be getting a Vikings 50 - 96 receiver by Eaton's circa 1948. Just the chassis and all components and I was told it was working when removed from the cabinet.
Just wanted to know if it's too much for a first attempt project.
Nicely done.
I love the meter !
Sounds good wish I knew how to do that kind of work.
Damn that sounds awesome!
Epic video Brad! Shame you never got paid properly for it though, dangit. The guy shoulda paid ya as you went, stripping down, redesigning, prototyping, soak testing, documenting & finally returning his dirty old box in the form of a fine guitar amp!
Sheesh, it's got that steam punk look about it mate it's a piece of art now. It used to be a big old mess.
Maybe a metal mesh 'cabinet' so you can see the cool, colourful glowingness going on inside as well as at the front?
It wasn’t his fault at all. He was a great customer. I appreciate him.
Right on brad now don't forget to stuff that beaver!!!
A masterful and amazing journey to be a passenger on. Question: why don't you use a non-contact infrared thermometer to see what's running hot?
Sweet Thanks Brad
Those capacitors were made in the town over from me, thats pretty cool. The first transistor was invented over there too.
NJ had a great electronics industry at one time. My mom worked at RCA in Camden after she got out of high school in 1962. You had IBM in Cherry Hill. Amazing stuff.
Sweet. You should take a trip sometime and see if you can locate and film the old factory.
@@TheGuitologist The Nipper Building is still in Camden, NJ only it's condos now, while the rest of the expansive factory sites were demolished in the late 80's/early 90's. Here's the wiki on the Nipper - en.wikipedia.org/wiki/Nipper_Building
This is where your Victrolas and such came from.
The Nipper Building in Camden still has the original stain glass art work of the RCA dog looking at the Victrola that RCA had used as their logo. I was a vendor for L3 Communications in Camden back in the eraly 2000's and they had taken me over to the RCA building (now Nipper Bldg) before it was converted to condos as L3 communications had purchased that building as well as all the RCA communications technology and equipment and gave me a tour. It was very cool
@@kensolo6793 So happy to see they saved that. Not only for history's sake but the fact that I love doggos and the connection to audio in general. That logo is burned into my brain from decades of seeing it.
Hum like a monk on a mountain top?😁
Dubillier Dry Caps are worth keeping , the later can earth aluminium type with 3 caps inside can read bang on after 50 years . I use them if I can find them as they save space . It must be the US side of Dubillier that called them 'Beaver ' as wtf has Beaver got to do with capacitors? Here they are just Dubillier Dry Cap , but you'll never get a leaking or even moist Beaver !
This is a radio designers idea of an amp , I was surprised not to see a quad of EFB89s as output tubes . Although these are typical radio tubes , they are a louder and shorter version of an EL84 . For cloth covered wiring gut old microwaves , they have quite a bit of HT red/black dash ptfe insulated single strand stuff that looks the part in old amps .
Hi Brad - I was also thinking about the rats nest that this amp looked like inside. I would imagine that since most of our "skilled" labor was off fighting war the country had to depend on a lot of unskilled labor in manufacturing, even many women had to enter the work force during the war to keep manufacturing going. I would imagine that because of the learning curve that these unskilled workers had to go through it is likely the reason that this assembly job looked so amateurish. Also, because of the expense of the war, many companies simply could not afford to "redo" sloppy work as long as the product worked and tested ok.
I will NEVER NEED THAT APP!
Mr. Carlson has a capacitor tester that he designed to test not only the current condition of capacitors but future possibility of failure
Mercury vapor rectifier. Sounds cool and dangerous. Those were the days. And those brownish old product catalogs are so beautiful.
I hope the filament wirings were filled with asbestos, if not, I am a bit disappointed. Just kidding. 😀
Very enjoyable video again. 👍👍👍 Thanks.
You were a little hard on The Beaver weren't you Brad ...Lol ... Good vid ...
I wonder if trying to over tighten the screw on the knob would’ve helped to break the glue bond? Prolly would’ve stripped the threads but might’ve distorted the plastic enough to break the bond.
Me: looks complicated as fuck
Brad: this is more complicated than it looks
😅
i would gut it start again
Hi Brad ,very interesting project this one,don`t suppose you know where I can get a copy of the Gibson amp book? cheers for the usual good work.
Hey Brad , you ever worked on a
Macintosh Power amp ??
Not yet.
Not many left I’d imagine. I got to use a rack full once with Tom Jones. That was a fun show. Lol.really super nice amps.
Whoa
Rad amp!
@@fuzzcityrecords432 Thanks Matthew! Your guitar will be coming soon. Gotta knock out a couple other things, then you.
Damn buddy you gave it a new life , ever thought about building your own amps? I get the feeling you would do very well.
i bet those little crazy batterys had something to do with the way the tube worked im trying to think what would need a little voltage to do something, i wonder if it was a bias thing to get the electrons moving
Fantastic.
I do a little tinkering on tube and SS amps......but at @ 1:09:00 ......well......it happens more than I like ! I know how to read a damn volt meter and oscilloscope so ......my confidence outweighs my knowledge.........by a long shot !
We call those Beavers..." LOOSEY "
😆
Most were stuffed too much up here!!
Oh fuck yes! Brad showing us amateurs how it's done :D
That wuz great... better than great, actually. So with the NFB loop, what happened and
did you try the amp with the NFB clipped out? (yes, thanx to you I'm a devout follower
of Uncle Doug) Yeah, with that 2 ohm tap you could do a 1 pc. Bassman thing with 4 x 8
ohm spkr's. So thanx so much for yet another great video and I hope all is well with you
Wish I had someone close I could go visit and learn more about electrical. Can't afford the gear beyond basic stuff. I'd like to progress past swapping HDMI and USB ports. I'd like to get a PCB made up and build a bomber soldering iron and hot air station. With all the bells and whistles. Copy the board from a brand name but fix where they built to cost.
Hey Brad, how many hours do you think you put in this thing after all is said and done? That looks SOOOOO much cleaner inside!
Did good on this one it rings ..
As far as testing the old caps.... unless you're testing them at their operating voltage, it's hard to tell how bad they are. Leakage is what usually "tricks" those component identifier testers to read high. I BET if you pull a brand new 100uf cap, it'll measure 99uf on there.... I know mine does.
Need to attach some stool legs on that Marshall head! Great sounding amp.
It sound realy good great video have a good day
I use a modified Dynaco Mk 3 my home guitar amp.
I wonder if that will fit in 19" rack?