1974 Fender Deluxe Reverb Part 1: Disassembly and Evaluation
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- เผยแพร่เมื่อ 29 ต.ค. 2013
- This is the first of three videos featuring the disassembly, restoration, and testing of a very nice, original 1974 Fender Deluxe Reverb. The chassis has some electrical issues as well as a non-functional Reverb and Tremolo, so this video series should offer some interesting insights into the repair process of these frequently troublesome sub-circuits.
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Thanks for watching !!! - เพลง
Doug, you are an outstanding example of everything that is right with the human race, i really enjoyed this video, and every vid of yours i've watched, regards to Rusty.
Wow, thanks so much, MS. Rusty and I truly appreciate your nice comments and are glad you enjoyed our video.
It's a real gem. I got the clean channel working today and the tone is spectacular. Next.....the tremolo and reverb.
Good advice, Kevin. Thanks for posting it.
Great video Doug. So many thanks for sharing your skills with us.
You're welcome, SS :)
Headed off to watch part 2 and just wanted to say how enjoyable your videos are. I wish I had gone down the electronics path when I was younger. I had a 1972 Deluxe silver face I played professionally for years. Great amps except when it would start "singing", but a good rap on top quieted it down! Thank you, Les
+Leslie Pierce You're welcome, Les. Thanks for watching :)
This is pure education for me. Thanks for posting these.
You're welcome, LF.
Nice find. you can hear the excitement in your voice. Congrats!
Marcel Pacheco Greetings, Marcel. Yes, I do tend to get excited when I find something nice like this in a pawn shop. Unfortunately, it happens very rarely nowadays. Thanks !!
Great news, Daniel !! I'm glad you were able to repair the amp and are now enjoying a "buzz-free" playing experience. I think you may be more of a technician than you're willing to admit......:))
Thanks for the video Doug, looking forward to the next video. Learning new stuff all the time. Take care to you and Rusty.
You're welcome, Mix. Same to you from Rusty and me :)
You did very well in lucking out on this magnificent vintage piece. "Excellent"
+John Cunningham Thanks, John :)
I have stumbled upon several of your videos on youtube, and each are well thought out, entertaining, and educational. Thanks for taking the time to make them!
+Christopher Brooks You're welcome, Christopher. Rusty and I are glad you enjoy our videos. Thanks for watching and commenting :)
Glad I stumbled here. I am looking forward to watching this series! :)
+Elsif Welcome aboard....we hope you enjoy the videos :)
Thanks, Dan. I'm working feverishly to get it finished.....
Great video as always! One thing I might mention is you should make sure the heater wires to the 6v6's are consistent. In preamp tubes, it doesn't matter, but making sure the heater wire from the first 6v6 on pin 2 goes to pin 2 of the second 6v6, same for pin 7. This allows hum-canceling to occur. Fender never paid attention to this, so about half the time, they're wired out of phase. Just a tip. Looking forward to the next videos!
Hi again Doug
You were right. It was one of the smaller tubes that caused the intermittent buzz! One of the pins going into the socket what bent flat, so the tube was loose. I straightened the pin and it fits nicely into the socket now. Sorted!! (I am not a technician as you can tell).
Thanks for the tip!
GREAT video. Thanks a ton for putting these out here.
Tony Clark Thanks, Tony. Glad you liked it :)
Doug, you really are awesome. I love your videos and get totally drawn in watching them.
Thanks, BC. We're really glad that you enjoy our videos.
Aw, Uncle Doug. You’re a genuine master. I have respect for your understanding and appreciation for Fender amplifiers. You’re my number 1 of all TH-cam. Take that from a guy who’s still working on tube amplifiers since 1978 in Ireland 🇮🇪
Thanks so much, Pearse. We really appreciate it.
We all Love all the educational videos you are so willing to share with us Tubers. I'm fortunate enough to have a 1 year old matchless that is my current baby. I wanted to snug up the mounting screws on the Power & Standby Switches. In doing so, I wanted to hold the switches on the inside, so nothing moved, which gave me the opportunity to peek inside. The craftsmanship internally looks immaculate. All is well at Matchless in Los Angeles and I'm excited to have the photos as I learn more and understand what it is I have. Thanks for all your videos Uncle Doug. . . . RodeDog !
Thanks, RD. That's great to hear :)
What you have here sir is my bucket list of amps
Awesome video Doug! I am hanging out for the next one.
I believe that virtually all new tubes are being made by just one or two manufacturers, so there's not a lot of difference between them. These particular 6V6's tested with higher emission levels than I have ever seen, including NOS tubes. They pegged my Hickok tube tester.
Uncle Doug As an interesting aside, the Maxi-Matcher people confirmed this and I have read that a number of foreign tubes are not exact replacements either. Also, I have found that Sylvania 12AX7s always test much higher than virtually all other 12AX7s. Most new US and European 12AX7s test around 1250. Sylvanias and some of the Eurasian ones test around 1650..
Love these 70's SF amps, and the Deluxe is my favorite flavor of Fender.
Their circuitry is virtually identical to the blackface amps, yet they sell for a fraction of the price. They are a huge bargain
Just found this channel so glad to see he just uploaded. New fan and subscriber for sure. We love uncle Doug
Thanks so much, Jason :)
This is why i sent back my new Delux reverb. It never looked like this inside! Wonderful stuff!
Thanks, Marc. The Silverface Fenders are great bargains. You can probably buy one for less than the price of a new reissue......and they are much, much better amps.
@@UncleDoug Never liked the reissue. Those older silver faces have a bad rep. Twas never sure why. We have less of the older amps in the UK. Making them rarer. More expensive. Lots of older Vox, Marshall available. At a very strong price. But they have both released amazing handwired amps.
The circuits of smaller silverface amps (Deluxe Reverb to Champ) are virtually identical (one or two small, rather insignificant cap values) to the blackface circuits......yet their value is less than half. To me, if you can get $2500 BF sound from a $750 SF amp, that's a bargain :)
Thanks, Frank. It's been a while since I found an amp of this magnitude. Earlier in the week, I felt a strong inclination to go amp hunting an area (out of town) that I hadn't been to in several months.....and there it was. Nine times out of ten, these "hunches" lead nowhere, but once in a while they pay off...:)))
Uncle Doug Hey Uncle Dudley this is Fred yeah I got my own dumb eyes on the pin your am son and the and oh poem come across to the right one At which time or I need to look for with the and known they are real good Jensen speaker in it of look at the date code on it gentle speaker in it Yeah this is the Anderson known gm1992@gmail.com and my you new to Uber as 9889 that is tell me another through a need to look at the date code on it safer has A Jensen speaker in a Don't you not doing your programs anymore you are you're out in their plan play in on your guitar knows your amps in thing I really do miss Ohn TH-cam seeming on TH-camYeah well will you have been doing of amicia on TH-camI'll be out there Joy
life since you're not on TH-camYeah I really do miss you Uncle totally New how's rustyIt's still sniff around her neck Whitman and things like thatNo please let me know my phone number is 1 the 4059335533 in coming time you more call me call me time fuel and get this the give me a call sometime when you take it easy now by
Yeah I'd rather than say thatgot my dumb I just I I really miss you truly T do
I don't know how I missed this one.I have the exact same amp 1974 all original.I love this amp I played a outdoor event with it 2 days ago.mine has the Utah speaker in it.This is a great amp.thanks for the video.
Thanks, Phil. I have since installed a new Jensen C12N, and it made a huge improvement in clean volume and tone.
if it wasn't for you I would never know what a decoupling cap is or why AC and DC can mix one the same wire. now I even understand the operation of some basic guitar pedals. thanks!
You're welcome, ST. We're glad the videos have provided some useful insights.
So many thanks for this and all your videos!
+SiliconSet You're welcome, SS :)
Thanks so much Doug.
This amp is a pretty nice find! :)
Thanks so much !!
I purchased a beautiful 1967 Drip Edge PR.a few years ago. Everything except the speaker and AC plug seem to be correct. I'm not trained in electronics like you but I have an intrest in it and I'm skilled enough to do a good and proper job of swapping parts, if I have good instruction. Your videos are a God Send, thank you. I moved from my home of 60 years and now I know nobody I would trust to work on my gear. The guy that worked on my gear before I moved was a musician that had made a living in amp repair since 1940. This guy is a tube amp guru. There are too many unqualified people out there claiming they know what to do with guitar amps. Your detailed instruction gives me hope that I can keep my gear in great shape. Thank You Uncle Doug.Peace, Hutch
You're welcome, Hutch. We're glad our videos are helpful and wish you the very best with your Princeton Reverb.
Is Rusty a Blue Healer?
That's what they told me when I bought him as a wee pup out of the back of a pickup truck parked at the side of the road.....and his parents (who were present) appeared to be Heelers.....but without a pedigree, it's anybody's guess :)
What a great find! I love the Fender Deluxe Reverb. My brother-in-law has a Twin Reverb and the rarer Fender Quad Reverb (both silver-face). But this Deluxe Reverb looks to be in better shape than either of his.
'Looking forward to seeing this one get the Uncle Doug "Deluxe" treatment!
Thanks, Steven. I still have this amp and it's still working perfectly. They're a little heavy to tote around, but otherwise, definitely one of Fender's best.
Bad Mann, your comment did not have a reply capability, so I'll reply up here. You're right, the speaker was replaced. This is discussed in the video at 4:55. Thanks for your input.
thank you Doug.
Thanks Doug! I will try.
Rusty also can also sniff out bad filter capacitors. I'd be lost without him :)
I once had s very nice collection of vintage Fender amps, with the majority of them being Deluxe Reverbs. Of all of them my most reliable and the one I loved the tone of the most is my '74. It's the only one I kept in my retirement.
Some people scoff at the Silverface Fenders, but many have BF circuits and wonderful tone......at very reasonable prices.
I acquired a '74 Twin Reverb 15 years ago. When I first got it, it would randomly make big popping noises. Took the chassis out and found that a coupling cap broke and it was arcing. I replaced that and it worked fine after that. It also had no reverb, and I found that one of the little tiny wires inside had broke off. Soldered that back on and it sounded beautiful after that.
Excellent work, VC. You appear to be quite competent at diagnosis and repair.
Thanks. I had some help from the amp debug page at geofex.com. I was just learning how to build stompboxes and work on amps at the time. Anyway, it said that popping noises were almost always due to arcing. In my case, the stripboard was curled up a bit and I could see where a blue Mallory cap had broke, so I replaced it. I think I just had luck on my side, but since then I have learned how to be a pretty good troubleshooter although I don't love the process of doing so lo
Uncle Doug Its a real treat to wach your videos...very informative...you do such professional quality work...trust me ...the average person has no were near the technical knowledge and skill you have...I would love to be your neighbor. .we have the same interest in vintage audio : )
I had one of these decades ago .. I sold it !!! It was a great blues amp ; just the right volume ;
They are a darned fine amp, L.
Fantastic, love your videos.
Hooray. Good for you. VERY much agree about that optowiggler ... weak and wimpy. Congrats (many years later!) on that Jensen. I have a '77 that has been messed with. I just got it two months ago (this is 16Sept2019), and it sounds like a small Super Reverb. I already have two of those, so I'm gonna find somebody who can turn it as close into a blackface Deluxe Reverb as possible ... We shall see ...
My favourite amp......of all time.
One of my all-time favorites too, Johnny, along with the Princeton Reverb. Thanks for your input :)
Nice amplifier. Very good condition.
+RODALCO2007 Thanks :)
Great vids! Makes me want to become a technician. I have a '72 with a few issues ( inermittent buzz that goes away when I tilt the amp?) and you give me the opportunity to try and sort the problems . Hope there is no difference with the '74
My main amp....to the year.... I love it. Fitted a 55hz Celestion Greenback...an English made one...Sounds amazing.
+Paul Fabrique Glad you like it, Paul. It's a great amp :)
Thanks Doug! It gives me hours of enjoyment...unfortunately the tube chart is missing its corners, but other than that , it perfect. It has the 5U4GB rectifier, which I can get get new old stock RCA types quite cheaply. The Mullard GZ34 are very expensive. The RCA 5U4GB are reliable though, the amp has had the same one for at least 25 years.
There is nothing wrong with 5U4's, Paul. A bunch of my old jukeboxes (and amps) have been using them for years with great results. I think the GZ-34 is better in some respects, but the 5U4 is a real workhorse :)
Thanks got a lot of great info out of this and subscribed.
You're welcome, Dirk. I'm glad the video was informative. Thanks for subscribing :)
Hi there--I love your videos, as they are very informative. And of course the good humor is always appreciated.
I just picked up a ~'78 Deluxe Reverb with the Push/Pull vibrato channel volume. Vibrato is not working, but everything else is great. Except when I tried to reduce hum by touching the ground switch--got a nice jolt last night.
I thought the same thing: "Why does a stock grounded power cable amp have a ground switch??" I'm sure the "death cap" must've passed A/C to the chassis, and then me and my guitar.
But I wonder if it may need another 12AX7 for renewed vibrato.
If the chassis was properly grounded, Taylor, there would be no shock hazard, "death cap" or not. First, you should test your wall receptacles to be sure they are properly wired and grounded. You can buy an
inexpensive testing device at Home Depot. If they are not wired properly, then repair them. If (or when) they are, then I suggest that you replace the power cord with a properly wired, 3-wire cord and be
sure that the green grounding wire is securely attached to the chassis. As far as the tremolo, replacing the oscillator tube would be a good first step. Good luck.
hi Doug wanted to say thanks for the knowledtge and sharing with us I have a fender ultra chorus I bought new back in the earlies 90s but all ways wished I got a tw
in reverb tube amp.wood only
witgive 150 for trade wants 700 for the 1978 twin reverb good deal Doug
Nice. Well done. I would just mention that you are probably safe in this case (a 74 amp) but in my experience about half the tube charts I have seen on BF amps are not the correct ones so take them with a grain of salt. Thanks!!!
Thanks, FL1. I appreciate your interest and input.
That's just a SWEET amplifier.
Thanks, TT.....and the best part is, I still own it :)
@@UncleDoug GOOD for you, Terry!! Wear that thing out! :-)
Great score!
Looks like a 56 pulp cone.
I haven't seen your follow up videos on this particular amplifier yet, but that speaker is going to break up very quickly and you will hear pure tube distortion at low volume. I don't believe that speaker would last long fully cranked up and would probably feedback, but would sound heavenly at lower volumes.
I prefer the Jensen C12N/Q or clone equivalent in this amplifier or a more efficient modern alnico that can handle it.
The ideal amplifier for that beautiful pulp cone old Jensen is in a lower wattage tweed era amplifier, 5 to 20 watts, if you like to crank them up like I do.
I've pushed all of the vintage alnico "P" speaker's and they always sound best just before the spider freezes up, lol.
I understand that this video is 7 years back, so I apologize if I'm preaching to the choir in the present, so to speak.
I'll keep an eye out for your follow up videos on this Deluxe Reverb. I'm curious about the GZ34 and the voltages.
The excitement in your voice is infectious my friend. Congratulations!
; )
Thanks so much for all the insightful comments, Amo.
@@UncleDoug
We did a blackface conversation on a 1971 Deluxe Reverb back in 96-97 and that amplifier was basically identical to your 1974. It most likely came with a Utah speaker from the factory with a brown'ish orange label.
I'm not a fan of those speakers and it's former owner didn't appear to be either. A lot of people love the JBL D120F, but I don't care for it in the Deluxe Reverb. However, in a Twin Reverb, they are much better, imeo. I learned a great deal from that blackface conversion, they are more complex tone-wise than other SF amplifiers. The switch to the 5U4 and the move from the 2.2K resistor to a 10K to the preamp section.
They also changed the taper in the volume pot that was for the worse, from smooth and even to a quick bump in volume. That's about all that I can remember at the moment.
Again, congratulations on a fantastic Fender amplifier.
@@amoruzz Thanks so much for the detailed input, Amo.
Thanks, Daniel. What a strange malady.....I wonder if a wire or tube filament is "loose" and responding to changes in position? Have you tapped on the tubes to see if one is microphonic? Also, maybe try moving the speaker and reverb cables around while it buzzes to see if you can pin point the source. Good luck.
I have an 95% original Fender Super Six Reverb with the six 10 inch. 5 of 6 speakers are original.Dated somewhere between 1974 & 1976.. Still works great!
Greetings, Pat. I'll bet that's a real monster to haul around :) I was wandering around in a local antique mall recently and happened upon a Fender amp that was a little taller than a Deluxe Reverb. The control panel was labeled "Super Six". Upon closer inspection, it appears that some lunatic had used a hand saw to cut off the bottom half of the cabinet (along with four of the speakers). They probably sold the bottom half separately as an "original" 4 x 10" Fender speaker cabinet :)
Hello. It's was cut down? That is sick Doug. I don't haul mine around. It sits in the basement to play from. I bought it in the early/mid 80's for $100 from a friend.
Wow, you definitely made a good buy, Pat. I'd hate to try to lug it up those basement stairs :))
As a novice and amplifier junkie I have really enjoyed expanding my knowledge watching your videos.
I lucked out at a sale and picked up a '78 DR for a song (relatively speaking).... another successful story of finally "lucking" out. The only thing that was amiss was the tremolo, so I had my tech friend throw on a photocoupler/wiggler and bias supply and filter caps onto his large order from mouser or whoever he goes through.
It is one heck of an amplifier---noticeably more powerful than the blackface amplifiers. All you have to do is leave the push/pull volume boost pot on the vibrato channel IN. I've never heard a more strident feature on an amp.
What kind of procedure would one go through to supply tremolo oscillation from one of the oscillating 1/2 tubes?
Did the amp come with a pedal? The Tremolo effect in most DR's requires that a pedal be connected for it to work. Your final question would require a very lengthy reply. I suggest that you watch my video on PhotoResistor/Bias Modulating Tremolos. Best of luck with your newly acquired DR.
The pedal and the original cover were unexpectedly present.
I'll watch that video with all speed, thank you.
P.S. How the heck did I miss this video. Classic teaching, Uncle Doug…..👍
We're glad you finally found it, Pearse. Thanks !!
I loved your video, I learned a lot. I subscribed.
That's great, Blanca. Thanks !!
"Drunken Chimpanzees" I formally resemble that remark! I used to work for AAMCO transmissions, but now I fix amps.
By coincidence, and to avoid being screwed by local fly-by-night transmission shops, I too learned how to rebuild TH350's and TH400 AT's. Our careers have followed similar paths......but in reverse order ;)
I've got a 1970 SFDR, that I bought while teaching at a music store locally in 1986 for $250.00.
That was probably a fair price at that time. Nowadays, you'd have to wear a mask to get it at six times that amount.
I have a great name for your band: “The White Spots.” Nice to see Rusty, by the way. I miss him. That dog had very good sense.
Thanks, Jeff. Yes, he did.
These are great amps. They get even better when they are moved into a MojoTone cabinet.
Thanks for your input, TT.
"worked on by drunken chimpanzees", haha hilarious. informative and entertaining, way to go, uncle doug.
+Sid Fernandez Thanks, Sid. I was contacted by the National Chimpanzee Anti-Defamation League and threatened with a lawsuit over the comment.....but I stand behind it (waaaay behind it) :)
We were talking about building a tremolo pedal the other day and I think your right. For me just buying a pedal would be the best idea. Thanks and sorry for being such a pest. I do like the videos tho and hope to see lots more
+357bullfrog It's a great way to add tremolo to any of your amps that don't already have it. Good luck.
I'm thinking of buying a Deluxe reissue and converting it to Point to point hand wired circuit board? UD "Decent" wow I'd die for that amp.
If the Deluxe in question works well, I doubt that conversion to P to P would make much difference in tone, Gary......unless you took the opportunity to incorporate superior components. Why not find one with a burned-up PCB (not that rare) at a give-away price and use it for your project.
Great video! I wish you would show how to check the output transformer and the reverb transducers thought
Thanks, Diego. Watch my video on the Impedance Ratio to better understand output transformer evaluation. About all you can do with reverb tank transducers is see if the coils have continuity. I have no way to measure their magnetic flux.
I'm actually rather amazed you don't have a solid answer for the outlet on back of the amp. I seem to remember trying to use one before and it caused hum in my signal chain. Regardless of what I did. The fan thing is a great idea, if I don't cause any noise issues. I wish I could run into a old Manuel telling use what fender had in mind. I've even thought about wrapping the power cord up then plugging it in the outlet for storage. Lol. Anyhow, if you ever nail down a answer let me know. Thanks Doug.
You're welcome, Bryan. Some things are just not meant to be known or understood :)
These power tubes (GT 6V6HD) are actually Russian 6Pi3C. Groove tubes marketed in the 90s. Its consumption is 900mA instead of 450mA. (as a 6L6). Care with them...
I'd be glad to pick up an old broken Fender amp, nice and cheap and I have the skill to fix them. Might as well have handed me a working amp. ;)
They're out there, LH, you just have to beat the bushes to find them :)
@@UncleDoug Not sure how I'd fair in Australia, but I'd certainly try.
Leave no bush unbeaten, LH :) Good luck. If all else fails, check Ebay.
cool
Doug wanted to know how to replace a speaker baffle in a Fender Super Reverb, my original baffle is let into the sides of the cabinet. Thanks
Rusty ROCKS!
Indeed, Tim. He is a multi-talented pup :)
My 69 Bassman head I just scored had white paint splatter on top! You're right!
The older the amp, the more likely it has the spatter. A viewer says that it's "spider poop".....and he may be right......but regardless, it's just about always present.
Eeeeeww!! Spider poop!
Thanks, 2005, and (unlike the 6:00 news).....no politics or dreary economic forecasts :)
My deluxe reverb is a '72 and is in almost similar condition. The difference is the speaker. My speakers have a Fender logo sticker on them.
Bear in mind that Fender does not manufacture any speakers. They are made by other companies, like Jensen and Oxford, and may have Fender stickers placed on them.
Beautiful amp.
I’m interested (at 44 years old) in learning about electronics (specifically amp circuits and design), what would be a good place to start from the beginning? Any books, videos, or other resources you can recommend? This would be a hobby, not necessarily a career.
Thank you for any direction you can provide.
The Internet is the best and most convenient source of information, Jeff......both videos and sites dedicated to tube circuitry. Once you have a foundation, the next step is to start repairing cheap tube amp circuits for yourself and friends. Eventually, you can begin to build your own amps from kits or from scratch. Good luck.
Doug,
How do you "divide and conquer" to find out where those popping noises are coming from? I know you can usually identify a problem before or after the volume by seeing if it goes up or down with volume, but I've got an amp with a hiss on top of the note and some popping sounds, and I haven't been able to find where it's coming from. Do you start replacing plate resistors ,first, coupling caps? grid leaks? I've swapped tubes and I'm sure the hiss on top of the note is not tube-related. The pops might be, but the old mullard 12ax7 that it pops worst with is dead quiet in another amp of mine. Thanks!
Joshua, if you have ruled out the tubes, then plate and screen resistors would be next to check. One way to quickly test components is with an aerosol can of electronics freezing spray....listen to see if the pops cease when a component is chilled. Here is a site that explains all sorts of other ways to track down the source: www.geofex.com/ampdbug/popping.htm Good luck.
Uncle Doug you have inspired me to make a tweed cabinet for my deluxe reverb. Do I need that heat shield that snags the control panel or can I can I get away without it? If I need it where can I get it? I'm also going to use an old Fender 022954 speaker that I have been saving for like 30 years, what do you think about that? Looking forward to hearing from you. Thanks for you great videos.
I'm glad to hear that you're inspired, BF. I doubt that you'll need a sheet of metal over the chassis.....it was originally for shielding from RF interference, and is no longer necessary. I have no idea as to the condition of the old Fender speaker, but if it works, then by all means use it. You're welcome.
tis a top of the line 70...looks like mine...the ex sold it when I went to Nam...
Leave it to the ex to sell off your most prized possessions while you're off defending the country ;)
This video was worth the price of admission when Uncle Doug says the words "Drunken chimpanzees"
We're glad you enjoyed it, M.
I meant, it would be nice for it to be used again.
I worked at Fender Santa Ana. Alot of stoners. Quit got my contracters license and ended up working on Corona plant. The deal with a Fender is we can fix. But once a lemon always a lemon
You should play more on your videos or if you feel too shy get someone else to play -- though your playing is fine. We the public want to hear those lovely sounds!
Thanks for your input, DD.
Very informative! Thank you!
Do you have any videos for blackface Twin or Deluxe Reverbs? Is there much difference between Blackface and Silverface?
You're welcome, Emiliano. I have never posted a video featuring either of the BF amps you mentioned. As far as the DR, the BF and SF models are virtually identical. I'm not sure about the twin. Download schematics for BF and SF Twins and compare them.
Rusty taught me how to sniff them out :)))
Hello, I did something pretty stupid today and I think I killed my Twin reverb reissue... I plugged the footswitch into the external speaker jack and practiced with it like that until it died. There was a lot of heat, but the amp was on the other side of the room so I dIdn't notice until it was too late.
I notice that it was not nearly as loud as usual but thought something else in the chain was causing the volume drop. It is dead now and wont turn on. Have I really killed my amp?
Thanks for any help you can provide!
You have probably damaged your output transformer and/or output tubes, David. If you have a multi-meter, test the OPT for continuity in the primary winding and in the secondary. If it's OK, which is a long shot, you could try installing some new or good used output tubes and see if that helps. Good luck.
Thanks Uncle Doug and Jack: I have a DRRI with a 16 ohm Greenback Speaker. I am looking to bias this amp for early breakup irrespective of output tube life for killer blues tone. Where should my output plate dissipations be set for these 6v6’s for this type of tone?
I didn't realize that the output transformer of a DR could support a 16 Ohm speaker, JF. Are you sure there is no impedance mismatch here? Re the tube bias, if you want it to have really nasty early breakup, then the tubes should be biased at maximum PD, which for grid-biased 6V6's is 70% of 12W or around 8.4W......and then either increase the resistance in the NFB loop, i.e. from 820 Ohms to 3K+ Ohms, or disconnect it altogether.
Uncle Doug You are correct. It is a 16 ohm speaker on a 8 ohm OT, which is the stock OT. I ended up getting a near mint greenback for $40 because get this, it was loaded into a wedge cabinet and he needed a full range speaker in there for vocals. I have learnt a wealth of knowledge from your videos.
OK, but bear in mind that the impedance mismatch will most likely have a negative effect on volume, tone, and tube life.
Uncle Doug, I've a couple of questions concerning amp wattage. On a few tube data sheets, plate wattage (for instance 16w) and output wattage (for instance 4.5w). Would an amp built using one of these tubes be rated at 16w or 4.5w? Another question is how wattage rating relates to volume, db? You run all of the amps you work on mostly through the same speaker and the volume sounds the same. Could be the balance on your camera but I am very curious. Thank you. Love the videos.
Plate Dissipation (i.e. 12W max for a 6V6) and Power Output (i.e. 24W) are completely unrelated measurements. Their only similarity is that they are both measured in Watts, which causes confusion. Power Output wattage does relate to volume, but the relationship is not at all linear, i.e. a 50W amps is not nearly twice as loud as a 25W amp. As the output wattage increases, the volume increases, but at a much lower rate. I run all audio tests at about the same audible volume, and the camera does compress really high volumes.
@@UncleDoug Thank you again UD, I really appreciate you and your knowledge.
I think I remember that a 12AU7 is a better tube to drive the reverb, as it makes it much less sensitive.
Thanks for your input, TT.
hi bro thanks for ur vids, i got a silverface deluxe but i want change to blackface circuits so u think that modifications can be done well and can make sf sound like a bf ?
You're welcome, Ben. If you look at the schematics for SF and BF DR's, they are virtually identical. Very few changes are required.
Hey Doug, Can you tell me what the right material is to use for a speaker baffle on a Princeton Reverb cabinet? Would that be 5/8ths ply?
I would think that 1/2" or 5/8" birch plywood would work well, Jeb.
Uncle Doug,I really enjoy all your videos. I have a Fender '65 Deluxe (re-issue) and the 6v6's area extremely HOT. I believe that Fender did this for some unknown reason. I have not taken the chassis from the cabinet yet. ATM, I'm working on a 5F2A amp and 6G15 reverb unit and all left is building the cabinet(s) and tolex, which I watched your video(s) on the tolex installation..My issue is the problem of the 6V6's getting HOT. I don't want to have replacing the 6V6's as they are not cheap. Is there a way to reduce the heat on the 6V6's (bias adjustment ?).Thanks, Tom...
You're welcome, Tom. Under normal conditions, the 6V6's get way too hot to touch, but if yours are creating excessive heat, the only way to reduce it that I know of is to adjust the bias to a proper level of Plate Dissipation (a maximum of 8.4W for fixed-bias or 12W for cathode-biased).
If you disconnect the reverb tank, can you blow your reverb OT, like you do with the SpeakerT, if no speaker load is connected?
An interesting idea, PK, that I had never considered. Since the reverb tank and its OPT act exactly like a speaker and its OPT......then, yes, perhaps you could; however, the reverb circuit is operating at considerably lower voltage and current levels.
Luckily, that did not happen... (I had issues reconnecting my restored reverb, which was rusty all the way incl. connections.) But it seems, that on my Fender Twin Reverb "Reverb Output" on the rear panel goes to "Output" on the reverb, which is very confusing to me. Is that normal for Fender Amps or are my connectors wired wrong?
(Normally I would expect, that reverb output goes into the input of the reverb and vice versa.)
I used to find it a little confusing too, PK. I believe that the output from the amp goes to the input of the tank, and vice-versa. You can determine this for sure by measuring the resistance (to ground) of each of the inputs on the tank. The values will be lower than the impedance of the inputs, but still informative. The amp circuit output should be going to the lower of the two resistances......actually about 8 ohms of impedance, so around 5 or 6 ohms of resistance. The tank is like a speaker, being driven by the reverb (i.e. output) transformer.
Thank you so much for your effort of answering and teaching me (us) a lot - actually I understand, what you are talking about, and two weeks ago, I would have no clue. And that all thanks to your great great videos.
Btw. I did (and still am) collecting a document with your slides and comments, neatly ordered, as a compact reminder of all the things you talk about. Do you have any interest of receiving that? Would that be useful for others as well? If you think so, I would be motivated to put it into a nice, more publicly acceptable form.
NIce.
+James Hurley Thanks :)
How do you calculate which fuses to use? Which of the transformer winding are the most important to protect?
If you don't have an AC ammeter to measure the input current, then install a 1W fuse and see if the amp starts up and works OK when driven. If the fuse blows, install a 1 1/2A fuse (if you can find one....or a 2A if you can't) and repeat the test. The proper fuse is the smallest value with which the amp can operate. All the windings are essential. The amp will not operate properly without them all.
@@UncleDoug I have both a digital and an analog meter. So it's sort of try it and see experiment?
Hi Doug, I've one 73 and I changed the PT and put to 240V (blackfacing with 5U4 for now). Should I switch the 2 amp fuse?
If you double the voltage, the current should drop to one half, Pablo, so I would try it with a 1A fuse. Turn it on and off a few times and run it at high volume to see if the 1A fuse can stand up to normal usage. If so, great....if not, try a 1.5A.
Ok, I will try this.
Thanks so much.
Regards!
You're welcome, Pablo. Good luck.
Your Videos are Outstanding, will the front panel just pop off for cleaning ? Peace !
Thanks !! Which front panel, MM......metal or cloth?
@@UncleDoug thanks for the reply I figured it out , it has velcro and the front panel pops off just had to work it free with a screwdriver, it's a silver face and it's the cloth front speaker panel sorry for not being more specific my bad, Thank You, Sir !
@@jixxxxer17 Glad you solved the problem, MM.
@@UncleDoug I did but now I have something new to deal with a really bad odor coming out of the amp once I got it in the house of course I started smelling it, it's a foul odor like a mix between cigarette smoke and a bad smelling old apartment i guess, any suggestions i would appreciate it i had to take the amp out of the house and put it in the garage now the smell was making me sick ugh , Peace !
@@jixxxxer17 You might try washing the grill cloth with Woolite and then letting it dry by having a fan blow on it all day.
Uncle Doug, you mentioned a fix For the hum coming from this amp but I didn't understand what you did exactly. Would you please explain to me exactly what you added to the circuit and where please? Thank you Uncle Doug
I honestly don't recall, Michael. If it's in the video, hopefully it will make sense if you listen carefully.
@@UncleDoug Thank you Uncle Doug
"And you see some spiderweb action going on its halloween" great sense of humor right there! Love it! But as an Arachniphobe EEKS!!! great vid greatful I subscribed! I'm a audiophile so that explains it I guess.
Ron Gay Thanks, Ron. Glad you enjoyed it :)
Uncle Doug, I've got a Deluxe Reverb here from '75, without a reverb tank.
I was wondering what Accutronics tank model you have here?
James, if you're looking for a really good-sounding replacement, my favorite is the MOD 4AB3C1B. Here is a link: www.amazon.com/MOD-Reverb-Tanks-4AB3C1B-Tank/dp/B003AZ3E5U I prefer the sound of these tanks to the currently made (in Korea, I believe) Accutronics tanks. They have a more "vintage" tone.
Uncle Doug Awesome, thank you for your swift reply. Great videos, by the way. Very helpful information.
You're welcome, James. I'm glad to have been of help :)
Whenever I come to restore something, I'm always going to add a spray of white emulsion in your honor 😅
Just dip a toothbrush, hopefully not your own, in white latex paint and snap it at the amp cabinet, P. Instant class !!
@@UncleDoug just what I was thinking! ... Wondered why my teeth have been squeaking...
If your married, use your wife's toothbrush :):)
@@UncleDoug I would have done, except she left me around two years ago, taking with her all toothbrushes, including the only thing I could never life without...