Re-capping a 1963 Blonde Tremolux

[olddawg]

I have a stock 1963 Blonde Fender Tremolux with two original speaker cabinets. No work has ever been done on it except tube replacement. It even has the original power cord. Recently it has been sounding a little thin with less sparkle and sustain than I remember it having. It has no hum, noise, or other issues. I have been contemplating replacing the filter caps since they are original. Are there other caps that are routinely replaced in this amp? I want to keep its value because it is so clean, but I do use the amp. Any advice is welcome on what to use and what is needed.

[J Martin]

Do the fiter caps and check the coupling caps for leakage. If leakage is only a few millivolts, you can usually let it pass. Over that, get them out of there.

jm

[52 Bill]

I'm sure that there will some advice here to re-cap the entire amp, but if it were mine, I'd make it sound right again, doing as little as possible to it.

"thin with less sparkle", may be off value coupling caps. Does it feel wrong in both channels or just one?

[TD_Madden]

As a safety precaution I'd definitely replace that two-conductor AC cord with a three-conductor....but keep the old one in case you want to restore for "vintage reasons".

[olddawg]

Yeah, I've thought of replacing the power cord but I use usually a transmitter live so I'm isolated. I have "see the light" a couple of times in studio though. The dullness is on both channels. Any recomendations on what brands and types of caps to use? I can check leakage on the coupling caps.

[Bruce / Mission Amps]

I'm sure that there will some advice here to re-cap the entire amp, but if it were mine, I'd make it sound right again, doing as little as possible to it.

"thin with less sparkle", may be off value coupling caps. Does it feel wrong in both channels or just one?

Thin and less sparkle is frequently the result of poor old, 25uF-25v cathode bypass caps in these old amps.
Ha ha... yup, I'm one that would recap the entire amp with new electrolytic caps, .... power supply, bias supply and eyelet board.
That, with correct power tube idle current, will really freshen it up if everything else is good.

[olddawg]

Thin and less sparkle is frequently the result of poor old, 25uF-25v cathode bypass caps in these old amps.
Ha ha... yup, I'm one that would recap the entire amp with new electrolytic caps, .... power supply, bias supply and eyelet board.
That, with correct power tube idle current, will really freshen it up if everything else is good.

This is a fixed bias amp. Torrez Engineering and others have a modification to make it adjustable bias. I'm considering that also but do not want to de-value the amp. I was suprized to see what these are going for nowadays. I have totally re-capped all of my old beater amps but this one is kind of my baby.

[stokes]

Another vote here to recap all the electrolytics.Sorry,Bill,but to make it sound right again those old caps gotta go.This wont devalue the amp half as much as some of those old caps exploding,and to me,I dont look at an amp for collector value,wont devalue it at all.Electrolytic caps have a finite lifespan,just like tubes,and should be replaced,I like the ten year rule,its not an absolute,but is what I was taught,and I still adhere to it and change mine every eight years or so.Those caps are 45 years old,no way they are doing their job efficiently anymore,and are very likely going to take a dive,and that will devalue the amp for sure.You will be amazed at how good the amp will sound and perform.As for the adjustable bias,except for the most finnicky collector,it shouldnt make a difference,I would do it as well.It is a definate improvement to someone who is going to play the amp and not put it in a museum.

[52 Bill]

Well, I won't get into a fight about re-capping, but I've never seen an old cap explode.

Years ago I used to do work for a storeowner who would take in an all original amp and tell the seller, "Well this amp isn't worth too much, because it will have to be re-capped to make it work right." But, he'd also tell the guy that brought in a re-capped amp "Well this amp isn't worth too much, because it's not in all original condition."

Re-cap, don't re-cap, it's up to you. My blonde '63 Bassman still works and sounds fine with it's original caps (for now at least).

[dai h.]

there was a guy some years ago on alt.guitar.amps who had an old JTM45 that had a cap explode inside it, and he had some pictures of it in that condition. It left a big mess inside the amp. I don't think such an example means a bad cap will always explode of course, but it definitely seems like it is a possibility.

[Bruce / Mission Amps]

Well, I won't get into a fight about re-capping, but I've never seen an old cap explode.

I have not seen old caps blow either.
Modern ones... sorry to say, yes.
But I have seen plenty of the old ones blow their vent caps open and spew junk all over the place!

Years ago I used to do work for a storeowner who would take in an all original amp and tell the seller, "Well this amp isn't worth too much, because it will have to be re-capped to make it work right." But, he'd also tell the guy that brought in a re-capped amp "Well this amp isn't worth too much, because it's not in all original condition."
.

Ha ha.. that is a classic, true hard core business man!!
At similar prices, I'd probably take the untouched one over a refurbished amp by an unknown tech just about any day!!

[stokes]

"But I have seen plenty of the old ones blow their vent caps open and spew junk all over the place!"
Wouldnt you consider that the same thing?Either way you describe it cleaning that mess up is a bitch.The older ones I've seen go didnt blow the cardboard surround apart,but when opened the alluminum was split,and the guts spewed in a kind of aimed, one direction,the new ones dont have the cardboard and had a much wider spread.

[stokes]

"that I just experienced my first capacitor explosion. Even better, it was a big cap can. I was just playin, and all of a sudden a loud explosion and a huge gust of smoke came shooting out of the amp in all directions. I assumed that I was completely screwed with no amp to play, but I realized it was just the cap can and I substitued new free standing caps. Black goo was squirting out from the top, and it was hot as fire. The damn thing was probably as old as the amp, produced in '65. Now that Ive fixed it, it was pretty neat seein this."

This was a post from another thread,in the Maintenance and Trouble shooting section.52Bill,apparantly I'm not the only one who has seen this phenomenom.

[52 Bill]

Stokes:
I didn't mean to imply that caps don't explode, they do. I've had caps explode on me, and I've also serviced plenty of amps that have shown signs of exploded caps. But my point was that it's not that common of a problem. I was only reacting to the general statement that uses this as a reason for replacing all caps in an amp. No offense was meant, and I appologize for anything I said.

[stokes]

No offense taken,Bill.Just thought there was an inference that older is better kind of thing,which is true for a lot of amp related things,and maybe you were saying that caps in old Fenders were somehow immune and dont explode,but caps do wear out,and there is a strong possibility for them to explode when they get beyond their limits.I understand the whole collector value thing,keeping things as original as possible,but not when it comes to filter caps.I think telling someone to leave 40+ year old caps in an amp they intend to play is bad advice.A supplier I had in downtown NYC showed me an advisory from Sprague or Mallory,I forget which it was,it was back in the '70's,that said their caps had a 10 year shelf life,so if the manufacturer claims it,why should we second guess them.From my own experience,I have never changed filters that were 10 years or older,and otherwise seemed fine,and not had the owner appreciate an improvement in the amps response.I would bet your '63 Bassman would benefit from a re-cap as well.But like they say,to each his own.