Talk me into fixing this Twin... again

G-Yo

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Somebody talk me into nursing this Twin back to health.


I have a mostly 1975 Silverface Twin Reverb. Bought it in about 2006 for about $400. I say mostly 1975 because it’s a 1975 amp chassis and guts, etc (according to the transformer codes), which has been installed into a newer Fender cabinet. Silverface control plate, with master volume. The speaker codes date to 1995, it has the velcro strap in the cabinet back for holding the foot switch, and there are extra holes in the top of the cabinet which are spaced wider than the screws/plate that hold the amp inside. So I guess the cabinet is from a 1995ish Twin or similarly sized fender amp. Speakers are Eminence with the blue Fender labels on the magnet.

It has always sounded great to me, although the reverb and tremelo have never worked. The reverb/trem channel worked, just not the effects (even with the foot switch engaged). The amp has been fun to play, and I really like the sound. It sounds like a Twin: big, loud, chimey, and clear. It’s also heavy.

Last Spring, it started popping and acting sputtery. A couple of times it did the thing where you switch it on and loud constant BZZZZZZTTT…… OK, fair enough, it’s probably time for things like capacitors, tubes, etc.

Now, I’m a mild tinkerer, but I don’t have the free time to learn all that’s necessary to diagnose and rework it myself. So, I took it to my local amp guy. He has done a good job with tube amps for me (and others) in the past; works out of his garage, and I think is otherwise retired. This time it took him waaaaaay longer than he predicted (like months and months). He rebuilt most of the insides, retubed it, but he wasn’t able to fix everything. For some reason, he couldn’t get the reverb/vibrato channel to work at all – I mean no signal/sound through that channel at all. He’s an older guy, I think he really tried, apologized for taking forever, and he didn’t charge me the time for attempting to fix the reverb channel. So, I’m disappointed, and maybe even a little irritated, but not angry at the guy. I do think he tried.

So, I’m playing the amp a few days after getting it back, and it’s popping. I figure it’s some stirred up dust burning off, or maybe some new components settling in, but it has continued over a couple of weeks (playing every other night or so). If I crank it a little and really strum hard, it pops loudly, pretty consistently. It also “farts out” a little with hard strumming.

Well crap. I like the amp, but all this popping and flubbering... I don’t want to have the same guy look at it again because 1) he took forever, 2) I don’t think he can fix it anyway and 3) I don’t want to get mad at the guy. OK, well I can either: a) live with it – sucky choice, b) take it somewhere else and spend probably a few hundred more, c) sell it for less than it might be worth and just be done with it, d) scour the internet over the next year or so, buy miscellaneous components and make various attempts at self-repair.

I’m in no danger of playing out any time soon; I haven’t done that in 15 years + other obvious reasons. I do have three other tube amps, but none of them have that Twin sound. So – somebody talk me into why I should keep it and get it fixed.
 

Blue Bill

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G-yo, I just fixed up my old Twin, I'm very glad I did. I had forgotten how good it sounds, and how much fun it is to play through. Go for it. It sounds like you need some new electrolyte caps.

Obligatory disclaimer: There's lethal voltage inside these amps, especially in the big caps, even when it's unplugged. Be safe.
 

Boreas

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My first suggestion would be to take it to a competent professional and have it repaired or replace it. It sounds like it has multiple problems and it is possible the garage tech made things worse. Those amps are quite complicated and probably should not be used as a learner amp to learn about amps and electronics. Download a schematic and see what you think.

That being said, amp repair isn't rocket science. What you are suggesting is indeed possible, but may not result in a satisfactory learning experience. Just changing caps and tubes isn't that complicated, but troubleshooting popping and dead trem/reverb circuits isn't for the novice. It will require knowledge you don't currently possess. You could get lucky and diagnose the problem quickly, or you may get frustrated from testing and re-testing components while trying to learn amp basics. But if you decide to give it a go, good luck!
 

dogmeat

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1. time to learn some new skills and fix it yourself. do a re-cap and tidy things up. re-solder anything that looks remotely suspicious. install known good tubes. if that doesn't do it, learn to trace the signal path. maybe start here
https://robrobinette.com/Amp_Stuff.htm

2. sell the amp to someone that will take it knowing that it has the problems that you fully describe. use that money and the money you saved by not paying some one to fix it to buy a good replacement. remember... it's big & heavy. I've been giggin 15-22 watt amps for years. plenty loud. any venue that needs more is mic-ed up anyway

3. pay someone you don't know to maybe fix it.

4. repeat as necessary
 

Twang Deluxe

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Somebody talk me into nursing this Twin back to health.


I have a mostly 1975 Silverface Twin Reverb. Bought it in about 2006 for about $400. I say mostly 1975 because it’s a 1975 amp chassis and guts, etc (according to the transformer codes), which has been installed into a newer Fender cabinet. Silverface control plate, with master volume. The speaker codes date to 1995, it has the velcro strap in the cabinet back for holding the foot switch, and there are extra holes in the top of the cabinet which are spaced wider than the screws/plate that hold the amp inside. So I guess the cabinet is from a 1995ish Twin or similarly sized fender amp. Speakers are Eminence with the blue Fender labels on the magnet.

It has always sounded great to me, although the reverb and tremelo have never worked. The reverb/trem channel worked, just not the effects (even with the foot switch engaged). The amp has been fun to play, and I really like the sound. It sounds like a Twin: big, loud, chimey, and clear. It’s also heavy.

Last Spring, it started popping and acting sputtery. A couple of times it did the thing where you switch it on and loud constant BZZZZZZTTT…… OK, fair enough, it’s probably time for things like capacitors, tubes, etc.

Now, I’m a mild tinkerer, but I don’t have the free time to learn all that’s necessary to diagnose and rework it myself. So, I took it to my local amp guy. He has done a good job with tube amps for me (and others) in the past; works out of his garage, and I think is otherwise retired. This time it took him waaaaaay longer than he predicted (like months and months). He rebuilt most of the insides, retubed it, but he wasn’t able to fix everything. For some reason, he couldn’t get the reverb/vibrato channel to work at all – I mean no signal/sound through that channel at all. He’s an older guy, I think he really tried, apologized for taking forever, and he didn’t charge me the time for attempting to fix the reverb channel. So, I’m disappointed, and maybe even a little irritated, but not angry at the guy. I do think he tried.

So, I’m playing the amp a few days after getting it back, and it’s popping. I figure it’s some stirred up dust burning off, or maybe some new components settling in, but it has continued over a couple of weeks (playing every other night or so). If I crank it a little and really strum hard, it pops loudly, pretty consistently. It also “farts out” a little with hard strumming.

Well crap. I like the amp, but all this popping and flubbering... I don’t want to have the same guy look at it again because 1) he took forever, 2) I don’t think he can fix it anyway and 3) I don’t want to get mad at the guy. OK, well I can either: a) live with it – sucky choice, b) take it somewhere else and spend probably a few hundred more, c) sell it for less than it might be worth and just be done with it, d) scour the internet over the next year or so, buy miscellaneous components and make various attempts at self-repair.

I’m in no danger of playing out any time soon; I haven’t done that in 15 years + other obvious reasons. I do have three other tube amps, but none of them have that Twin sound. So – somebody talk me into why I should keep it and get it fixed.

That's the reason why I sold my 1977 Super Twin Reverb. I would sell it and buy a TMTR.
 

Boreas

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If you want to get a feel for the complexity, check out some of Uncle Doug's videos on YouTube. He has numerous videos that involve Twins specifically. He is an excellent teacher and if you can't understand or don't feel comfortable digging in after watching a couple, then you should probably not dig too far into it.

 

Wally

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Don’t turn it on again before you either find a tech or sell it. Ommv. It is way past time for the amp to be properly serviced....new electrolytics, good general service—-cleaning, tightening, etc. you may find that all problems disappear with such service. If not, then it would be time to find the cure for those problems.
 

Jukers

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Well, it all depends on you with what you should do. If it's your favorite of the heard, then send it to a competent tech. If you don't want to spend the money, or care about it, then sell it as is.

That amp should get the love that it deserves. If Fender ever does make another Twin Reverb, that is point-to-point, it would cost out the wazoo!! A normal Silverface Twin Reverb, that will probably need service at this point, cost usually around $800-$1200. YOU are a big step ahead of the game. You've already got the hand wired amp already!!.... but with some grimlins and headaches.... errr that sucks....

It sounds like you've got a few things wrong with it. I would find the right tech and see what the quote is before making a decision. You don't know exactly what it will cost at the moment.

Good luck and thank you for keeping the love for these old amps!!
 

d barham

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Take it to a qualified tech. Have him fix everything that needs fixing. If you’re not happy with it after that, at least it’ll be in good shape to sell.
 

BobbyZ

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That amp should get the love that it deserves. If Fender ever does make another Twin Reverb, that is point-to-point, it would cost out the wazoo!!

Crazy thing is a later silverface Twin Reverb would probably cost more to do today than a blackface. I know the insides of my 76 TR look like someone just tossed in wires and the insides of my '65 look like an artist wired it. But the later TR would take a more skilled person to solder up. All those wires have to go in the right way or it'll have all kinds of issues.
And that's not even considering the difference in wire! Blackfaces had cloth covered stuff you gotta try to eff up. That late SF stuff melts if you look at it funny!
Anyway I'd imagine 4k would be about right, from Fender for a hand wired one today.
If you did the inflation calculations that's probably close to what the originals cost in today's money, ok maybe 3k. They weren't cheap!
 

Wally

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1976 TR list price...$635. In today’s money, that would be just a few dollars over $2900. I don’t think Fender would do a handwired RI for that. A ‘63-64 BFTR cost $3988 in today’s money. Fender might do that???? But...who wants to pay that for a straight ahead amp with too much power and no versatility??!
Here is the bargain in the handwired era...the 1982 Super Champ cost
$806 in today’s money. What a steal!! By the end of the run, they had escalated to today’s $1064! Still a bargain....find someone to build you a quality reverb amp with high gain capability for that money???
a Rivera era TRII??? That amp in today’s money cost $2477.
 

G-Yo

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You guys are awesome. Thanks for all who replied. I really appreciate your thoughts, and all are helpful. I think I’m going to take it to a known reputable place and at least get a price for repair. If it’s reasonable, I’ll have it repaired and keep it. Or sell it. But probably keep it. If it’s $800 to fix (it won’t be…), then all I’ve lost is the bench fee.

So, in answer to some of the questions: the guy who worked on it has been an amp tech working through various music shops for many years. He’s working out of his garage now, and probably transitioning to retirement. So, he was a professional tech, and still kind of is… I can’t name every component he replaced, but I do know he retubed it, tightened/cleaned the tube sockets, cleaned all of the pots, and “rebuilt” the tone stack, gain stage (1st or 2nd or both, I don’t know, etc). He did not replace the choke or any transformers.

David Barnett – Yes. I cleaned the tube sockets a couple of years ago, and the tech who worked on it cleaned and tightened them.

Blue Bill – Thanks! Yes, I like how it sounds when it’s running well. Yes, the tech who just worked on it replaced all of the electrolytic caps… which is good because as you pointed out, they can be dangerous if you’re clumsy with them.

Boreas – Yep, solid words, thanks! I think this guy is very knowledgeable and at one time was a good tech, he’s probably just “winding down” if you know what I mean. And you’re right about getting lucky or getting frustrated if I attempt repair. I know my skill level and don’t really want to endure my own learning curve on this. I’d rather be playing. :) But – those Uncle Doug videos look really informative. I might watch and learn even if I don’t decide to delve in!

Dogmeat – thanks, man!
  1. It is recapped and tidied, and the tubes are all new. Tracing the signal path is probably not going to happen if I task myself with it…
  2. I’ve had that exact same thought. In fact, I have a Silverface Champ in a custom cabinet with a 12” Weber speaker. That thing gets plenty loud for my needs!
  3. Yeah – I don’t know this guy personally, but I get your point. If I take somewhere that is more like a place of business, I might get better results.
  4. Life is all about try, try again, right?
BobbyZ – see above. My best recollection from what he told me. Yes, he replaced all of the caps; I figured they would have been the culprit. And yeah, it’s crazy to think what a recreation of these old amps would cost today, hand made in USA. Same thing with cars, buildings, all kinds of things.

Twang Deluxe – Right? Yeah, I was considering that or something similar. I’ve heard good things (and not so good things) about the TMs and the Boss Katanas. I'll probably try them in a store anyway, just for fun.

68tele – Agreed. I thought they were one in the same in this case, but hindsight = 20/20.

Wally – Yep, all of those things have been done (by garage guy). Still not quite right.

Jukers says: “I would find the right tech and see what the quote is before making a decision. You don't know exactly what it will cost at the moment.” Ding ding ding! Winner!

d barham – Yep, was thinking about that. Do you think the fact that it’s a 75 amp in a 95 body with ’95 speakers would reduce the value much (once it’s all working)?
 

Wally

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Pull all tubes. Fire it up...is the noise there? If the noise is there, you may have a bad switch, a rectifier circuit problem or a bad PT??? If the noise is not there, , you may have a bade tube or a bad contact in a socket. Get some contact cleaner, spray the tube pins and reinstall the tubes...starting with the power tubes. Insert and pull each tube a few times. With all four power tubes in the amp, fire it up. If the noise is there, one might suspect a power tube....or a bad component in the output circuit.l.including the output transformer. If there is no noise, then proceed with the same procedure for the 12A-7s...one at a time moving from the power tubes back through the circuit toward the inputs. If and when the noise is present, you have a clue as to where the problem lies.
Do you take voltage measurements? If not and if you do not want to move into tech work, it is time to put the amp on someone’s bench. ...or time to sell as is.
 

Wally

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Value??? I don’t see how the newer cab and speakers could reduce the value much. TRs have reached the bottom of the value, one might think. I don’t see how they sell new Reissues. An amp such as yours is a better value imho, if a person wants a big amp.
 

Musekatcher

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The Twin design, all of them, I think are a bullet proof design that is timeless, in that they achieved the goal, which was an absolute goal. Its about loud, clean, dynamic, and broad scooped frequency range for a guitar input. They are heavy for a reason.

The best device available to achieve the 1970's silverface sound that is the signature sound for so many recording and performing artists, is a lowly 1970's silverface itself. The closest thing available from Fender, is a'57 Custom Tweed for $3k. Their regular production Twin is a nice $1500 BF amp, but not PTP, weighs 14 lbs less, meaning less transformer, or less speaker, or both, etc. A Lonestar or clones are going to run a similar price. And they will be heavy for a reason.

So Its a bit of an enigma, that you can easily find THE original for $500 with original speakers, add $3-400 in servicing, and you have THE signature sound that inspired more artists than anything else. For $900 bucks. US made, PTP, etc. Or, find one with JBLs or EVs for $700, and you have a flagship timeless classic for $1100? An equivalent new build, with JBL clones is probably going to push $3500.
 
Last edited:

G-Yo

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Alright, so I am still going to take it to a different known-entity tech (probably after the holidays), and see what the repair cost is.

In the meantime, it occurred to me that it could possibly be something with the speakers. So, I tried hooking the TWIN to a known good speaker (matching ohms), and also hooking the TWIN's speakers up to a known good amp (also matching ohms). At first I couldn't make the Twin amp buzz with different speakers. It sounded great. AHA! Then, I couldn't make the Twin speakers buzz with a different amp. Um... ok..? Eventually, I was able to reproduce the crackle/buzz sound using different speakers, but it was with the MV turned down less than half way, and the channel volume cranked. Didn't seem as pronounced as before, but it was there. Again, this is a slight static/buzz/scratchy sound as if you were turning a dusty pot, but it happens when you strum a chord loudly, or hit one of those B notes on the low E. Maybe it's a vibration thing?

So, I'll share this info with whatever tech I bring it to, and see if it sheds a little light.

Test area photos, just for fun.
IMG_9112.jpg

IMG_9115.jpg
IMG_9116.jpg
 

Oldsmobum

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Alright, so I am still going to take it to a different known-entity tech (probably after the holidays), and see what the repair cost is.

In the meantime, it occurred to me that it could possibly be something with the speakers. So, I tried hooking the TWIN to a known good speaker (matching ohms), and also hooking the TWIN's speakers up to a known good amp (also matching ohms). At first I couldn't make the Twin amp buzz with different speakers. It sounded great. AHA! Then, I couldn't make the Twin speakers buzz with a different amp. Um... ok..? Eventually, I was able to reproduce the crackle/buzz sound using different speakers, but it was with the MV turned down less than half way, and the channel volume cranked. Didn't seem as pronounced as before, but it was there. Again, this is a slight static/buzz/scratchy sound as if you were turning a dusty pot, but it happens when you strum a chord loudly, or hit one of those B notes on the low E. Maybe it's a vibration thing?

So, I'll share this info with whatever tech I bring it to, and see if it sheds a little light.

Test area photos, just for fun.
View attachment 799116
View attachment 799120 View attachment 799121

Did the cat have a look too? Never be too sure...
 
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