Uncle Doug- I am always amazed by your museum quality approach to restoration up to the point of replicating design flaws for the sake of correct reproduction. The grill cloth I would have just chucked, but you got great result with that and the Fender logo. I think I found my next expensive hobby. Thanks, I think!
UncleDoug - "Orange sticks" were also used in Silicon Valley production and engineering shops to adjust pots without causing a short due the the wood rather than metal. Especially handy back when computers had CRTs with very high voltages that needed adjustment to fine tune the picture. Nice work BTW! I enjoy watching a pro work on tube amps.
Thanks, CA. When I worked on radios, it was common to use either wooden or plastic screwdriver-tipped tools to align the RF stages. Their insulation provides safety and they create less "noise" when making adjustments.
I don't know the first thing about amp restoration, I wish I did. However, I thoroughly enjoy watching your vids on so many of these gems. My favorite is the Mighty Mouse you built. It must be very fulfilling and enjoyable having this knowledge and working on these amps. Thanks for sharing all of this info. While I love Fender amps, it's especially neat to see the insides and how things work.
Thanks, Ronnie. I'm glad you're enjoying the videos. By "Mighty Mouse" I think you're referring to my clone of a tweed Fender Bassman. That was the most complex and challenging amp I have built so far. Please continue to watch the videos (there are 91 so far), and feel free to ask questions if something is not clear. I really appreciate your interest and comments :))
Thanks for your kind words and good luck with your restoration, Eric. They are wonderful little amps, certainly worthy of the work required to put them back into good condition. I am posting a video featuring an absolutely pristine mint 1967 Princeton Reverb (it is in my shop for repair) that you will really get a kick out of.....it even has the original cover, hang tag, and footswitch.
+Jean-François Joubert No kidding, J-F.....same with the back door on a 3 x 15 Kustom speaker cabinet. They definitely didn't want the back door to fall off during a performance :)
Yes, Fender biases them way too hot (in my opinion). You probably should get a tech to reduce the plate dissipation values for the tubes......or do it yourself (if you are experienced with high voltage electronic work). Thanks for posting and best of luck !!!
very nice work im doing the exact same thing to a 1964 Princeton non reverb that had the grill and some of the face plate painted, I still has the "paper" caps and its in perfect condition other wise
Amazing job on restoring the grill cloth; very fortunate the audio output transformer was not damaged when the 6V6 tubes went. I suspect it was due to the poor speaker restoration that killed the tubes.
+John Cunningham Thanks, John. Also, the tubes were in the wrong sockets when I got the amp, and I have a feeling that it had been plugged in and turned on that way :(
I just started doing a restoration on my 1968 silver face I bought new back in the day. I'm enjoying your restoration and I started watching it in order to help myself understand the best way to proceed. I can relate to your desire to keep the amp as original as possible but I wish you had looked at the perceived value of the Oxford speaker before you tried to fix it. In most cases it detracts from the value (it is generally considered worst than the Utah replacement that I had in mine). I have to warn you though, lacquer thinner on a plastic based fabric could spell disaster down the road. Any aggressive solvents can leach into the molecular structure of hydrocarbon based plastics and cause disintegration in a matter of months.
Greetings, Rick. I do try to preserve originality whenever possible. My motivation is not primarily financial, but doing what is best for the amp itself. Saving the "patient's" own organs is always preferable to transplantation. Re the damaged Oxford speaker, it now rests comfortably on a storeroom shelf while an appropriate vintage Jensen speaker is installed in the amp. If the amp is sold, I'll pass along the Oxford to the new owner. Re the grill cloth, I did my best to preserve the original. If it disintegrates in the next few months (no evidence of that so far) then I'm no worse off than if I simply replaced it in the first place. Meanwhile the nice, mellow, original grill cloth is in place. Thanks for your input.
For your question - at 06:08 - why the cloth needs to sand away from the wood: Bass tones make the front cloth to vibrate at high volumes. You really do *not* wanna have this. It sound terrible when the cloth hits the wood. To prevent this fender uses the wood surrounding to inbuild a gap to prevent the woold beeing hit by the cloth. Remember old tube radios where the cloth hits the wood while playing music with deep bass in it....awful...;)
Very interesting....I would not have thought that the sound of cloth vibrating would even be audible, but I have heard this explanation several other places and guess it must be true. On my next cabinet build, as an experiment, I will use this method to suspend the grill cloth above the speaker baffle. Thanks !!!
Uncle Doug AS i´m ca club member of our local -radiomuseum linsengericht- I also do old radio restaurations and i really hate when cloth vibrating adding its -brrr- to the bass....but i also know that instument amps are -by far- more louder than old tube radios..:)
Manuel, there could be several reasons for the "saturated" sound, including a worn out, floppy speaker and improper bias adjustment. The 6V6 cathodes are grounded in the Princeton, so changing of bias requires either adding a resistor between the cathodes and ground, or adding a potentiometer that will allow you to adjust the bias. You should aim for (0.7 x 12 x 2 =) about 17 watts of plate dissipation at idle. If none of this makes sense, then get a tech to do it for you. It can be dangerous.
For 06:30 next time you may try if your washing mashine can´t do the job for you, I´ve done this with some old cloth for tube radios and it worked out just fine.
I too have used the trusty washing machine (and dishwasher) from time to time to clean grill cloth and parts (much to my wife's disgust). In this case, however, since it was spray paint, I had to resort to lacquer thinner to remove it.....much like "drycleaning" that uses solvents rather than water to remove stains.
Hi Doug, Thanks so much for the very informative videos. Lots of great detail - I am learning lots from your videos. I recently purchased a 1962 Fender Bassman head that has also been painted. I have started to strip the paint off the back door and am having good success so far. There are two coats of paint on the amp so it is taking quite a bit of time. I have a question about how you got the paint off of the grille cloth. When you used the toothbrush with laquer thinner to strip the paint, did you then wipe the remaining laquer off with a clean cloth or did you clean the cloth afterwards? Any issues with the cloth distorting or wrinkling during the process?Your results look fantastic! Thanks so much for all of your videos - I enjoy every one of them and will miss Rusty in the future ones. Jack has big shoes to fill! Thanks Steve Couch
You're welcome, Steve. Thanks for your nice comments. With regard to the cleaning of the grill cloth with lacquer-thinner, as I recall, I submerged the cloth in lacquer cleaner to soften the paint, then removed it gently with a toothbrush while it was in the lacquer thinner. I then removed the cloth from the thinner and laid it on a clean towel to blot out the thinner and residual paint. It's hard to describe in detail......I simply experimented and stuck with what worked. Good luck.
Hey nice vid man! I've got an early 70's silverface and right now its 100% stock, but in working order. I was wondering if you think changing out the tubes and/or a new speaker would help the tone/possibly boost the volume? Thanks!
+Abe Thedrummer Thanks, Abe. In my opinion, if the amp is working well and sounds good, then leave it alone. If it's down on volume, then you might consider changing and re-biasing the output tubes. If the original speaker is worn out and flubbing, then change it. But if not, then use it as-is.
Thanks for you reply, The Saturation is something like a Fuzz or Overdrive past 2 or 3 volumen. Such resistance and potentiometer that would value. which connect the potentiometer and how do the measurements? (I have knowledge of electronics)
Hello Good sir. I wanted to send you a message telling you that you are amazing! Thanks for this series! I have a 64 Princeton NON reverb that my father gave to me. However, the tubes red plate even with new tubes(JAN 6V6's). I think I need to do what you did to the PT sockets with the 100Ohm Resistor to drop my PV. Do I measure the plate voltage from pin 3 of the socket? Then I solder the 100ohm Resistor to the chassis from pin 8? Thanks again!
Greetings, Jorma. Since your tubes are red-plating, I would suggest adding even more resistance. Try a 200 Ohm resistor from pin 8 to ground on each tube. See if this stops the red-plating and still gives good tone. If they still red-plate, then add more resistance. Yes, pin 3 is the plate of the 6V6. Your plate voltage should be somewhere between 400 and 430 with the added resistors. Good luck !!
Uncle Doug Hey there. I checked the bias of each socket using my dual bias probe. the red plating tube skyrockets in voltage to 200mV+ the other is about 20mV. I dont let it redplate to long as these are NOS tubes. Any ideas? Seems that maybe one side is getting all the volts. Can I check the PV w/o tubes? Ive always had a standby switch. Thank you for your advice!
Jorma, I have never heard of a tube drawing over 200mA (I believe you meant to say mA instead of mV). Since these are new tubes, I strongly suspect that the one drawing 200mA may have a short circuit of some sort. If I were you, I would check all the wiring to the socket, check to be sure the tubes really are 6V6's, and then try another pair of 6V6's in the sockets to see how they behave. If you don't have another pair of 6V6's, then reverse the ones you have in their sockets. If the problem follows the tube, then it's the tube that's bad. If the problem stays with the same socket, then its the socket. Good luck !!
***** Jorma, I'm wondering if there may be no grid bias to the (hot) tube. Without any grid bias to suppress the plate current, it would tend to go real high. Check the voltage at pin 5 of each 6V6 to see if they are equal. If they aren't, i.e. one at -35VDC and the other at 0V, then check the value of the 220K resistor that connects to pin 5. It may be open.
Uncle Doug !! I am sure the Fender gods smile on you from on high !! You certainly have more patience than I do. It would never enter my mind to remove paint from a grill cloth - but you definitely resurrected it from certain death !! I have a question for you. I heard in this video that you have/use a Hickok 200A tube tester ! When I try to research tube testers - I feel like Alice - falling down the rabbit hole of complexity !! Have you considered doing a video on tube testers ? Were there specific criteria for your choice of the Hickok 200A ? What would you recommend for use with guitar amp tube testing ? As always - thanks a ton for your generous sharing of expertise !! -- Don
Don, I am definitely not an expert on tube testers. I was fortunate to be able to buy my Hickok tube tester Iocally many years ago. I really didn't select it.....it was simply the best one that was available and it appeared to serve my purposes.They appear occasionally on Craigslist and quite frequently on Ebay. There are several Internet sites dedicated to debating the relative merits of various testers, and that's probably the best source for the information you seek. Best of luck :)
Uncle Doug Thanks a ton for the response Unc Doug !! I guess I'll embark on my usual excruciating data gathering and evaluation process - re: deciding on a tube tester !! Should be fun !! (:>}
Watch the video (I am going to post within the next 24 hours), on the Rickenbacher 59. In it I demonstrate the usefulness of my Hickok 600-A tube tester :)
I swear- my guess was 111 staples. The amount of stapling seems about right to hold that grillcloth 100% straight, and seems on par to what I've seen from fender grills in the past.
+Uncle Doug just give me a few more numbers of things to guess so I can fill out the card with the lucky numbers. I have never played, but seriously considered it recently. If I win, I'll take a bunch of time off of work and we can go amp hunting.
That's the best offer I've had since Emily Blunt was in town filming Sicario.....and begged me to run away with her. Naturally I couldn't, because she was allergic to Rusty :) :)
Manuel, the biasing procedure is too complicated for me to describe in a UA-cam comment. I suggest that you do a Google Search for Amplifier Biasing Procedure, or perhaps look for a UA-cam video that describes the procedure. Good luck.
09:30 why are you running this tubes so hot? It is real close to Class A PP. The tubes wear out much faster on this high current. In my Amps i usually run the output tubes on 30% may up to 50%. Just enough to overcome the conducting gap when the signal is zero crossing. The whole amp stays colder, the tube lasts longer and in the end the amp will be much louder;)
It's my experience that plate dissipation is the best indicator of tube heat and life expectancy, rather than just plate current. It seems that vintage PR's all seem to have outrageously high PC and PV, and I generally try to reduce the PD to safe levels.
May do a test an run them as low PD as possible and hear the sound and compare the sound (do a record session, or so) between your settings, to the more technican settings witch simply overcome the conducting gap in any Class AB PushPull Amp...;) You may discover that 10-20% of PD max. will do just fine. And you´ll be given 2-3 times of Output Tube life. I tried this with my Laney 100W tube head (100W super PA) and found that the lower (technical) settings are nice.
The Oxford 10L5 is hands down one of the best guitar speaker I've heard. I don't get it. why don't people like oxfords haha??? I would never put anything else in my 67 Princeton appart from maybe a Jensen C10N! 10L5's have Big sound/Bold/tight bass/sparkling highs, very efficient without being modern and not too scooped in the mids (but maybe this is what you crazy strat/tele players old dudes who can only play one loosy surf riff and played it for 50 years do plug in those amps? Archtops, Dearmonds, CC pickups, P90s, McCartys, Pafs... anything litteraly SHINES through it. anyone trashing those big magnets oxford are WRONG. Those speakers are magic, and anyone who likes a lush/magic/thick clean tone should reconsider those puppies
I really enjoy your videos, but is there any reason why you are uploading everything in 360P resolution? It seems like your camera must be recording at a higher resolution than that, perhaps 720 or 1080. So much more detail would be visible to the viewer if you could upload the videos in a higher resolution - 480P at the minimum. Thanks.
I'm sorry the resolution is poor, David. I do record in 720, but during the conversion and uploading process, apparently the resolution is degraded. I will check into it. Thanks for the input.
Uncle Doug Thanks. It could be when you're exporting the video from your editing program. When you export see if you can adjust the video quality to make sure that it's not mixing it down to a lower resolution. UA-cam will always keep the same resolution as what you upload. So if your original file is 720, it will be that way on youtube, so I would assume the downgrading is happening somewhere within your editing program before you try to upload it. Also make sure you have your camera set to record at 720 and don't have it in some sort of low quality setting.
Uncle Doug Not necissarily. Does your editing software give you control over what format you export to? And if so does it allow you to stipulate the resolution? Even if it's WMV you should still be able to set it to 720. I personally export all my videos into H.264 codec. After I edit a video and export/compress it I am able to chose the codec and the resolution that I compress it to. Perhaps if you're using a really cheap editing program it might restrict your options, but I would think you could at least export in the same resolution that you are importing into it from your camera. See if you have more options when you export your final edit.
why not just add a trimpot to the bias supply and make it adjustable? Adding those 100 ohmers to ground, I would have thought would make it a bit squishier and give it less headroom (not in a good way). Just a thought
That's exactly what I did in another video featuring the restoration of a 1966 Fender Princeton Reverb (which is currently posted on my channel). In fact, it worked out so well that I converted the amp in this video to adjustable bias also and eliminated the cathode biasing resistors.
ah cool, good to know :) That's good since it means you can now install new 6V6s and rebias easily instead of messing around with desoldering/resoldering marginally different cathode resistors.
Yes, the re-biasing procedure now takes about a minute or two. With a single bias adjustment, however, the 6V6's must have fairly well matched plate current values....but this is no different than the majority of other adjustable bias amps. Cathode biasing each tube individually with its own resistor value can compensate for PC mismatch, but, as you mentioned above, this does alter the performance characteristics of the amp somewhat (particularly at high volume levels).
Uncle Doug Didn't Fender do this cathode resistor on some Silverface amps? The result being a) it didn't work b) it sucked tone, these amps also had the bias balance circuit. To drop the plate voltage could you swap the rectifier to a 5R4/5Y3.
Greetings, Squiz. It wasn't the plate voltage that was troublesome.....it was the plate current, and the disparity in PD between the two tubes. The amp actually worked and sounded just fine with the cathode biasing, but I returned it to fixed bias a little later (as God and Leo intended) and installed a bias adjusting pot, as in the Deluxe Reverb. All of this is featured in a subsequent video on my channel. Thanks for watching and for your input :)
Hello Uncle Doug, and thank you for sharing your time, talent, and seemingly endless energy. I’m putting in my bid to guess the correct number of staples used on the grill cloth of your your 1967 Princeton Reverb. I guess 123 staples. I’m trying to learn as much as I can because my 1968 AA764 Princeton Rev. (ser.#A20972) is throwing a fit. I’m not a tech. Sure wish I could just box it up, and send it to you. Is that possible? J. Justin Zimmerman JJZ...(°¿.°`)
Your staple guess was pretty close, JJ, but the nut platter is long gone :( I'm taking a break from repair work at the moment, but can recommend a couple good techs who can fix it for you. Contact me by FB message at: Uncle Doug's Vintage Amps.
@@UncleDoug I’m sorry, but I did my best looking for a way to email you through FB. I haven’t used Facebook since 2012, and still my account WAS valid. New password, and off I went, looking for a way to contact you, or send a message. Maybe I was in the wrong place, but I was definitely where your friends were leaving Uncle Doug’s Vintage Amps a post. My email is ebony9cat@yahoo.com I would truly appreciate your help finding a Tech I can trust as I’ve recently found the Tech I’d been working with for 3yrs is a pirate. I witnessed many unscrupulous practices happening in his shop...not to mention his telling me that my ‘65 Princeton rev.’s transformer was shot. Meanwhile, a ‘68 Deluxe Rev. was on his bench getting a new rev. transformer. Luckily, the previous week he had ordered four new transformers. Hmmm. Again, I apologize for not understanding FB. Your help would be greatly appreciated. Thank you, Justin Zimmerman JJZ...(°¿.°`)
Anything is possible with this poor speaker. It's obvious that the person who worked on it had no knowledge or skill when it came to speaker re-coning.
Chris, Fender PR's are famous for outrageous plate voltages. The tremolo circuit modulates the grids of the 6V6's and interferes with proper grid biasing. I have seen unmodified PR's with plate voltages in the 460V range, and with 6V6's in which the plates have partially melted. I generally add resistors to the cathodes to reduce plate dissipation to safe levels.
After you´re done so much to the speaker, i AM really *sorry* to tell you this is some sort of a !frankenstein! speaker. Here´s why: The chassis itself comes from a Pyle Driver, because i got one here myself and it looks absolute the same. Next up the magnet is totally different, since pyle driver got a hole in the back to breathe and air change. This one do not a hole. The magnet must be from the original speaker because of its diameter fits to the original inner cone segment. The cone is from the original speaker, the surrounding is nither from the original nor from pyle. It is from a HiFi speaker...pyle uses cloth, the original may the same paper as the cone itself, but nerver ever used rubber for surroundings in a back opened cabinet. Holy cow....this is terrible, even whorse than my 15 inch scary example i show people how *not* to do a ReConig, they simply glued the voice coil onto the the cone by utilizing the hotgun glue! YES some idiot done it with a hot glue gun....it is a 15 inch PA speaker; the fane colossus first series!... Here´s the story: the glue began to melt again, the voice coil removed particular from the cone and the speaker blow off....great shot..bown away a 800W decent PA speaker of its time with damn hot glue!
Are you sure, Tubical ?? I compared this speaker to several 10J4-5B Oxfords from PR's of the same vintage, and, other than the cone, it is an exact match. Check some Ebay ads and I think you will see this. You can even see where the green dot was next to the left terminal.....and the anodizing of the basket matches the magnet.
Uncle Doug I do not have the speaker next to me, but when i show it, you´ll see. The back on my pyle ist the same that you have and you have done a very good replacement, not to say the best possible ;)
I've heard this before and still can't visualize how a piece of cloth could generate a sound loud enough to be heard over an amplified guitar......but I guess anything is possible.
Thanks, Don. Your kind words make it all worthwhile.
Nice job restoring the grill and Fender logo.
The furring strips were to keep the grill cloth from potential rattle against the baffle. That FENDER logo looks fabulous!! Incredible tube matching!!
Thanks, TT.
Uncle Doug- I am always amazed by your museum quality approach to restoration up to the point of replicating design flaws for the sake of correct reproduction. The grill cloth I would have just chucked, but you got great result with that and the Fender logo. I think I found my next expensive hobby. Thanks, I think!
You're welcome, John. It can be a bit expensive, but very rewarding. Keep us posted on your new hobby :)
Course, now, I can't get too much old Princeton data. Thanks Uncle Doug- as always, great stuff!
UncleDoug - "Orange sticks" were also used in Silicon Valley production and engineering shops to adjust pots without causing a short due the the wood rather than metal. Especially handy back when computers had CRTs with very high voltages that needed adjustment to fine tune the picture. Nice work BTW! I enjoy watching a pro work on tube amps.
Thanks, CA. When I worked on radios, it was common to use either wooden or plastic screwdriver-tipped tools to align the RF stages. Their insulation provides safety and they create less "noise" when making adjustments.
I don't know the first thing about amp restoration, I wish I did. However, I thoroughly enjoy watching your vids on so many of these gems. My favorite is the Mighty Mouse you built. It must be very fulfilling and enjoyable having this knowledge and working on these amps. Thanks for sharing all of this info. While I love Fender amps, it's especially neat to see the insides and how things work.
Thanks, Ronnie. I'm glad you're enjoying the videos. By "Mighty Mouse" I think you're referring to my clone of a tweed Fender Bassman. That was the most complex and challenging amp I have built so far.
Please continue to watch the videos (there are 91 so far), and feel free to ask questions if something is not clear. I really appreciate your interest and comments :))
Thanks for your kind words and good luck with your restoration, Eric. They are wonderful little amps, certainly worthy of the work required to put them back into good condition. I am posting a video featuring an absolutely pristine mint 1967 Princeton Reverb (it is in my shop for repair) that you will really get a kick out of.....it even has the original cover, hang tag, and footswitch.
So many staples... It reminds me of a Traynor amp I used to have... the back door that closed the speaker cabinet had about 60 screws? Crazy!
+Jean-François Joubert No kidding, J-F.....same with the back door on a 3 x 15 Kustom speaker cabinet. They definitely didn't want the back door to fall off during a performance :)
Yes, Fender biases them way too hot (in my opinion). You probably should get a tech to reduce the plate dissipation values for the tubes......or do it yourself (if you are experienced with high voltage electronic work). Thanks for posting and best of luck !!!
very nice work im doing the exact same thing to a 1964 Princeton non reverb that had the grill and some of the face plate painted, I still has the "paper" caps and its in perfect condition other wise
A very interesting theory.....thanks for posting.
Amazing job on restoring the grill cloth; very fortunate the audio output transformer was not damaged when the 6V6 tubes went. I suspect it was due to the poor speaker restoration that killed the tubes.
+John Cunningham Thanks, John. Also, the tubes were in the wrong sockets when I got the amp, and I have a feeling that it had been plugged in and turned on that way :(
well i got this story from Gerald Weber,he has tons of tips about Fender amps,he knows a lot about the construction of any single model
The black paint actually preserved the original grill clothe!
I guess.....but it sure looked like hell.
I just started doing a restoration on my 1968 silver face I bought new back in the day. I'm enjoying your restoration and I started watching it in order to help myself understand the best way to proceed. I can relate to your desire to keep the amp as original as possible but I wish you had looked at the perceived value of the Oxford speaker before you tried to fix it. In most cases it detracts from the value (it is generally considered worst than the Utah replacement that I had in mine). I have to warn you though, lacquer thinner on a plastic based fabric could spell disaster down the road. Any aggressive solvents can leach into the molecular structure of hydrocarbon based plastics and cause disintegration in a matter of months.
Greetings, Rick. I do try to preserve originality whenever possible. My motivation is not primarily financial, but doing what is best for the amp itself. Saving the "patient's" own organs is always preferable to transplantation.
Re the damaged Oxford speaker, it now rests comfortably on a storeroom shelf while an appropriate vintage Jensen speaker is installed in the amp. If the amp is sold, I'll pass along the Oxford to the new owner.
Re the grill cloth, I did my best to preserve the original. If it disintegrates in the next few months (no evidence of that so far) then I'm no worse off than if I simply replaced it in the first place. Meanwhile the nice, mellow, original grill cloth is in place.
Thanks for your input.
For your question - at 06:08 - why the cloth needs to sand away from the wood:
Bass tones make the front cloth to vibrate at high volumes. You really do *not* wanna have this. It sound terrible when the cloth hits the wood. To prevent this fender uses the wood surrounding to inbuild a gap to prevent the woold beeing hit by the cloth. Remember old tube radios where the cloth hits the wood while playing music with deep bass in it....awful...;)
Very interesting....I would not have thought that the sound of cloth vibrating would even be audible, but I have heard this explanation several other places and guess it must be true. On my next cabinet build, as an experiment, I will use this method to suspend the grill cloth above the speaker baffle. Thanks !!!
Uncle Doug AS i´m ca club member of our local -radiomuseum linsengericht- I also do old radio restaurations and i really hate when cloth vibrating adding its -brrr- to the bass....but i also know that instument amps are -by far- more louder than old tube radios..:)
So why do the tweed champ and bassman dont have them? Are the grill cloths flat against the baffles? Thankyou!!
Manuel, there could be several reasons for the "saturated" sound, including a worn out, floppy speaker and improper bias adjustment. The 6V6 cathodes are grounded in the Princeton, so changing of bias requires either adding a resistor between the cathodes and ground, or adding a potentiometer that will allow you to adjust the bias. You should aim for (0.7 x 12 x 2 =) about 17 watts of plate dissipation at idle. If none of this makes sense, then get a tech to do it for you. It can be dangerous.
For 06:30 next time you may try if your washing mashine can´t do the job for you, I´ve done this with some old cloth for tube radios and it worked out just fine.
I too have used the trusty washing machine (and dishwasher) from time to time to clean grill cloth and parts (much to my wife's disgust). In this case, however, since it was spray paint, I had to resort to lacquer thinner to remove it.....much like "drycleaning" that uses solvents rather than water to remove stains.
Uncle Doug
It turns out to be ´pain in the ass´ work to utilize laquer thinner.....uuuh holy cow what a stench....
Yes, and the fumes can damage your liver, but if you end up with a nice grill cloth it's all worth it :)))
Well done. Great restoration.
Thanks, Michael.
grill cloth does look great! and logo
Thanks, Chris. It was a miserable job, but it turned out OK.
07:50 AWESOME work!!
Thankyou :))
Hi Doug,
Thanks so much for the very informative videos. Lots of great detail - I am learning lots from your videos.
I recently purchased a 1962 Fender Bassman head that has also been painted. I have started to strip the paint off the back door and am having good success so far. There are two coats of paint on the amp so it is taking quite a bit of time. I have a question about how you got the paint off of the grille cloth. When you used the toothbrush with laquer thinner to strip the paint, did you then wipe the remaining laquer off with a clean cloth or did you clean the cloth afterwards? Any issues with the cloth distorting or wrinkling during the process?Your results look fantastic! Thanks so much for all of your videos - I enjoy every one of them and will miss Rusty in the future ones. Jack has big shoes to fill!
Thanks
Steve Couch
You're welcome, Steve. Thanks for your nice comments. With regard to the cleaning of the grill cloth with lacquer-thinner, as I recall, I submerged the cloth in lacquer cleaner to soften the paint, then removed it gently with a toothbrush while it was in the lacquer thinner. I then removed the cloth from the thinner and laid it on a clean towel to blot out the thinner and residual paint. It's hard to describe in detail......I simply experimented and stuck with what worked. Good luck.
'Paid by the staple' hilarious!
Glad you liked it EJ :)
I bought pots to add adjustable bias, would you recommend that over this method?
Hey nice vid man! I've got an early 70's silverface and right now its 100% stock, but in working order. I was wondering if you think changing out the tubes and/or a new speaker would help the tone/possibly boost the volume? Thanks!
+Abe Thedrummer Thanks, Abe. In my opinion, if the amp is working well and sounds good, then leave it alone. If it's down on volume, then you might consider changing and re-biasing the output tubes. If the original speaker is worn out and flubbing, then change it. But if not, then use it as-is.
Thanks for you reply, The Saturation is something like a Fuzz or Overdrive past 2 or 3 volumen. Such resistance and potentiometer that would value. which connect the potentiometer and how do the measurements? (I have knowledge of electronics)
Hello Good sir. I wanted to send you a message telling you that you are amazing! Thanks for this series! I have a 64 Princeton NON reverb that my father gave to me. However, the tubes red plate even with new tubes(JAN 6V6's). I think I need to do what you did to the PT sockets with the 100Ohm Resistor to drop my PV. Do I measure the plate voltage from pin 3 of the socket? Then I solder the 100ohm Resistor to the chassis from pin 8? Thanks again!
Greetings, Jorma. Since your tubes are red-plating, I would suggest adding even more resistance. Try a 200 Ohm resistor from pin 8 to ground on each tube. See if this stops the red-plating and still gives good tone. If they still red-plate, then add more resistance. Yes, pin 3 is the plate of the 6V6. Your plate voltage should be somewhere between 400 and 430 with the added resistors. Good luck !!
Uncle Doug Hey there. I checked the bias of each socket using my dual bias probe. the red plating tube skyrockets in voltage to 200mV+ the other is about 20mV. I dont let it redplate to long as these are NOS tubes. Any ideas? Seems that maybe one side is getting all the volts. Can I check the PV w/o tubes? Ive always had a standby switch. Thank you for your advice!
Jorma, I have never heard of a tube drawing over 200mA (I believe you meant to say mA instead of mV). Since these are new tubes, I strongly suspect that the one drawing 200mA may have a short circuit of some sort. If I were you, I would check all the wiring to the socket, check to be sure the tubes really are 6V6's, and then try another pair of 6V6's in the sockets to see how they behave. If you don't have another pair of 6V6's, then reverse the ones you have in their sockets. If the problem follows the tube, then it's the tube that's bad. If the problem stays with the same socket, then its the socket. Good luck !!
*****
Jorma, I'm wondering if there may be no grid bias to the (hot) tube. Without any grid bias to suppress the plate current, it would tend to go real high. Check the voltage at pin 5 of each 6V6 to see if they are equal. If they aren't, i.e. one at -35VDC and the other at 0V, then check the value of the 220K resistor that connects to pin 5. It may be open.
Uncle Doug !! I am sure the Fender gods smile on you from on high !! You certainly have more patience than I do. It would never enter my mind to remove paint from a grill cloth - but you definitely resurrected it from certain death !! I have a question for you. I heard in this video that you have/use a Hickok 200A tube tester ! When I try to research tube testers - I feel like Alice - falling down the rabbit hole of complexity !! Have you considered doing a video on tube testers ? Were there specific criteria for your choice of the Hickok 200A ? What would you recommend for use with guitar amp tube testing ? As always - thanks a ton for your generous sharing of expertise !! -- Don
Don, I am definitely not an expert on tube testers. I was fortunate to be able to buy my Hickok tube tester Iocally many years ago. I really didn't select it.....it was simply the best one that was available and it appeared to serve my purposes.They appear occasionally on Craigslist and quite frequently on Ebay. There are several Internet sites dedicated to debating the relative merits of various testers, and that's probably the best source for the information you seek. Best of luck :)
Uncle Doug
Thanks a ton for the response Unc Doug !! I guess I'll embark on my usual excruciating data gathering and evaluation process - re: deciding on a tube tester !! Should be fun !! (:>}
Watch the video (I am going to post within the next 24 hours), on the Rickenbacher 59. In it I demonstrate the usefulness of my Hickok 600-A tube tester :)
Uncle Doug
Sweet !! Thanks for the heads up !! {:>)
I have this amp but it sounds saturated, has new tubes will be BIAS adjustment problem? as I can fix it?
I swear- my guess was 111 staples. The amount of stapling seems about right to hold that grillcloth 100% straight, and seems on par to what I've seen from fender grills in the past.
+Joel Thomas You should play the Power Ball Lottery, Joel......excellent guess :)
+Uncle Doug just give me a few more numbers of things to guess so I can fill out the card with the lucky numbers. I have never played, but seriously considered it recently. If I win, I'll take a bunch of time off of work and we can go amp hunting.
That's the best offer I've had since Emily Blunt was in town filming Sicario.....and begged me to run away with her. Naturally I couldn't, because she was allergic to Rusty :) :)
Found it. 👍
Seems you didn't lose you mind, merely misplaced it. Happy reunion...
Manuel, the biasing procedure is too complicated for me to describe in a UA-cam comment. I suggest that you do a Google Search for Amplifier Biasing Procedure, or perhaps look for a UA-cam video that describes the procedure. Good luck.
09:30 why are you running this tubes so hot? It is real close to Class A PP.
The tubes wear out much faster on this high current. In my Amps i usually run the output tubes on 30% may up to 50%. Just enough to overcome the conducting gap when the signal is zero crossing. The whole amp stays colder, the tube lasts longer and in the end the amp will be much louder;)
It's my experience that plate dissipation is the best indicator of tube heat and life expectancy, rather than just plate current. It seems that vintage PR's all seem to have outrageously high PC and PV, and I generally try to reduce the PD to safe levels.
May do a test an run them as low PD as possible and hear the sound and compare the sound (do a record session, or so) between your settings, to the more technican settings witch simply overcome the conducting gap in any Class AB PushPull Amp...;) You may discover that 10-20% of PD max. will do just fine. And you´ll be given 2-3 times of Output Tube life. I tried this with my Laney 100W tube head (100W super PA) and found that the lower (technical) settings are nice.
OK, I will check into this. Thanks.
Uncle Doug
No need to, thas why we here for; learn, think and have some FUN!
grill cloth was suspended,otherwise it would rattle against the baffle.
I have a ser. No. of
A 05783 on my champ
Amp can you tell me what year mo. It is Uncle Doug?
Do a search for How to Date Fender Amps by Serial Number Part VI, Dwight. You'll find all the answers there.
137 staples?
The Oxford 10L5 is hands down one of the best guitar speaker I've heard. I don't get it. why don't people like oxfords haha??? I would never put anything else in my 67 Princeton appart from maybe a Jensen C10N!
10L5's have Big sound/Bold/tight bass/sparkling highs, very efficient without being modern and not too scooped in the mids (but maybe this is what you crazy strat/tele players old dudes who can only play one loosy surf riff and played it for 50 years do plug in those amps?
Archtops, Dearmonds, CC pickups, P90s, McCartys, Pafs... anything litteraly SHINES through it.
anyone trashing those big magnets oxford are WRONG.
Those speakers are magic, and anyone who likes a lush/magic/thick clean tone should reconsider those puppies
Thanks for sharing your opinion with us, Clement.
I really enjoy your videos, but is there any reason why you are uploading everything in 360P resolution? It seems like your camera must be recording at a higher resolution than that, perhaps 720 or 1080. So much more detail would be visible to the viewer if you could upload the videos in a higher resolution - 480P at the minimum. Thanks.
I'm sorry the resolution is poor, David. I do record in 720, but during the conversion and uploading process, apparently the resolution is degraded. I will check into it. Thanks for the input.
Uncle Doug
Thanks. It could be when you're exporting the video from your editing program. When you export see if you can adjust the video quality to make sure that it's not mixing it down to a lower resolution. UA-cam will always keep the same resolution as what you upload. So if your original file is 720, it will be that way on youtube, so I would assume the downgrading is happening somewhere within your editing program before you try to upload it. Also make sure you have your camera set to record at 720 and don't have it in some sort of low quality setting.
Before uploading, I am converting to WMV format. Could this cause the degradation of resolution?
Uncle Doug Not necissarily. Does your editing software give you control over what format you export to? And if so does it allow you to stipulate the resolution? Even if it's WMV you should still be able to set it to 720. I personally export all my videos into H.264 codec. After I edit a video and export/compress it I am able to chose the codec and the resolution that I compress it to. Perhaps if you're using a really cheap editing program it might restrict your options, but I would think you could at least export in the same resolution that you are importing into it from your camera. See if you have more options when you export your final edit.
I'll check into it, David. I am using the editing program that came with the Sony camera, so it's probably not the best. Thanks for all the info :)
why not just add a trimpot to the bias supply and make it adjustable? Adding those 100 ohmers to ground, I would have thought would make it a bit squishier and give it less headroom (not in a good way).
Just a thought
That's exactly what I did in another video featuring the restoration of a 1966 Fender Princeton Reverb (which is currently posted on my channel). In fact, it worked out so well that I converted the amp in this video to adjustable bias also and eliminated the cathode biasing resistors.
ah cool, good to know :) That's good since it means you can now install new 6V6s and rebias easily instead of messing around with desoldering/resoldering marginally different cathode resistors.
Yes, the re-biasing procedure now takes about a minute or two. With a single bias adjustment, however, the 6V6's must have fairly well matched plate current values....but this is no different than the majority of other adjustable bias amps.
Cathode biasing each tube individually with its own resistor value can compensate for PC mismatch, but, as you mentioned above, this does alter the performance characteristics of the amp somewhat (particularly at high volume levels).
Uncle Doug Didn't Fender do this cathode resistor on some Silverface amps? The result being a) it didn't work b) it sucked tone, these amps also had the bias balance circuit. To drop the plate voltage could you swap the rectifier to a 5R4/5Y3.
Greetings, Squiz. It wasn't the plate voltage that was troublesome.....it was the plate current, and the disparity in PD between the two tubes. The amp actually worked and sounded just fine with the cathode biasing, but I returned it to fixed bias a little later (as God and Leo intended) and installed a bias adjusting pot, as in the Deluxe Reverb. All of this is featured in a subsequent video on my channel. Thanks for watching and for your input :)
Hello Uncle Doug, and thank you for sharing your time, talent, and seemingly endless energy. I’m putting in my bid to guess the correct number of staples used on the grill cloth of your your 1967 Princeton Reverb. I guess 123 staples. I’m trying to learn as much as I can because my 1968 AA764 Princeton Rev. (ser.#A20972) is throwing a fit. I’m not a tech. Sure wish I could just box it up, and send it to you. Is that possible?
J. Justin Zimmerman
JJZ...(°¿.°`)
Your staple guess was pretty close, JJ, but the nut platter is long gone :( I'm taking a break from repair work at the moment, but can recommend a couple good techs who can fix it for you. Contact me by FB message at: Uncle Doug's Vintage Amps.
@@UncleDoug I’m sorry, but I did my best looking for a way to email you through FB. I haven’t used Facebook since 2012, and still my account WAS valid. New password, and off I went, looking for a way to contact you, or send a message. Maybe I was in the wrong place, but I was definitely where your friends were leaving Uncle Doug’s Vintage Amps a post.
My email is ebony9cat@yahoo.com
I would truly appreciate your help finding a Tech I can trust as I’ve recently found the Tech I’d been working with for 3yrs is a pirate. I witnessed many unscrupulous practices happening in his shop...not to mention his telling me that my ‘65 Princeton rev.’s transformer was shot. Meanwhile, a ‘68 Deluxe Rev. was on his bench getting a new rev. transformer. Luckily, the previous week he had ordered four new transformers. Hmmm. Again, I apologize for not understanding FB. Your help would be greatly appreciated. Thank you,
Justin Zimmerman
JJZ...(°¿.°`)
now i know why my siLverface princeton cooks it's 6v6 tubes .
112!
The speaker has the wrong cone. That cone is for a woofer.
Anything is possible with this poor speaker. It's obvious that the person who worked on it had no knowledge or skill when it came to speaker re-coning.
like
Thanks :)
392 volts.!!.what ?? I though 350 volts was maximum for 6V6
Chris, Fender PR's are famous for outrageous plate voltages. The tremolo circuit modulates the grids of the 6V6's and interferes with proper grid biasing. I have seen unmodified PR's with plate voltages in the 460V range, and with 6V6's in which the plates have partially melted. I generally add resistors to the cathodes to reduce plate dissipation to safe levels.
After you´re done so much to the speaker, i AM really *sorry* to tell you this is some sort of a !frankenstein! speaker. Here´s why:
The chassis itself comes from a Pyle Driver, because i got one here myself and it looks absolute the same. Next up the magnet is totally different, since pyle driver got a hole in the back to breathe and air change. This one do not a hole.
The magnet must be from the original speaker because of its diameter fits to the original inner cone segment.
The cone is from the original speaker, the surrounding is nither from the original nor from pyle. It is from a HiFi speaker...pyle uses cloth, the original may the same paper as the cone itself, but nerver ever used rubber for surroundings in a back opened cabinet. Holy cow....this is terrible, even whorse than my 15 inch scary example i show people how *not* to do a ReConig, they simply glued the voice coil onto the the cone by utilizing the hotgun glue! YES some idiot done it with a hot glue gun....it is a 15 inch PA speaker; the fane colossus first series!...
Here´s the story: the glue began to melt again, the voice coil removed particular from the cone and the speaker blow off....great shot..bown away a 800W decent PA speaker of its time with damn hot glue!
Are you sure, Tubical ?? I compared this speaker to several 10J4-5B Oxfords from PR's of the same vintage, and, other than the cone, it is an exact match. Check some Ebay ads and I think you will see this. You can even see where the green dot was next to the left terminal.....and the anodizing of the basket matches the magnet.
Uncle Doug
I do not have the speaker next to me, but when i show it, you´ll see. The back on my pyle ist the same that you have and you have done a very good replacement, not to say the best possible ;)
If you don't suspend the cloth it will buzz like a kazoo.
I've heard this before and still can't visualize how a piece of cloth could generate a sound loud enough to be heard over an amplified guitar......but I guess anything is possible.
So why do the tweed champ and bassman dont have them? Are the grill cloths flat against the baffles? Thankyou!!