Re-capping My Marshall

[ES335TD]

Hi folks,
I've been told my 50 watt Marshall Bass amp from the early '70's needs to be re-capped. What caps would you recommend? Thanks!

 

[Zemaitis]

I'd go with F & T's first, and If I couldn't find them, JJ's work nicely.

 

[Cygnus X1]

Not necessarily a DIY job...if you don't know what you're doing.
Deadly voltages even when unplugged.

 

[bluesforstevie]

Hi folks,
I've been told my 50 watt Marshall Bass amp from the early '70's needs to be re-capped. What caps would you recommend? Thanks!

This type of thing drives me bonkers. Who told you that? Exactly WHY do they need to be replaced?

What did YOU hear? Hum? Ripple? Weird overtones etc? Or is this person just saying remove them because they're old?

If the latter is the case, I can't tell you emphatically enough to trust your own ears. If the amp sounds fine to you....it IS fine. If some part is bad, the fuse will blow before anything fatal happens to your amp and its trannies.

Please, don't replace them because they're old. Unless you are a Pro musician who plays and earns most your dimes doing so...keep the old ones in there...there's magic in them old parts many times and I tell you...I've yanked caps just because I thought I should...and have made a magical amp sound sterile.

If they do need to be yanked, the second post is a good answer!

 

[ES335TD]

Here's the response I received with pics. The amp sounds fine.

"Attached are the pictures of the filter caps in your Marshall JMP that should be replaced. I am looking for other possible replacement caps that are closer in dimensions and appearance to the original Daly 50uF-50uF 500 V cans."

 

[bluesforstevie]

Those aren't even power caps are they? Those are the electrolytics on the board. What about the picture says they need to be replaced? They look fine to me...and you say the amp sounds fine? Don't fix what ain't broke.

 

[zombiwoof]

Those aren't even power caps are they? Those are the electrolytics on the board. What about the picture says they need to be replaced? They look fine to me...and you say the amp sounds fine? Don't fix what ain't broke.

Doesn't that cap in the middle of the pic look like it's bulging and leaky?. Sort of looks that way to me (the end looks leaky, and the body looks to be misshapen). The other one on the left looks OK. He probably figured if the one was getting bad, the other might as well be replaced also.

Al

 

[Diablo1]

If it were my amp, I'd replace every electrolytic cap in it. Those caps are 40+ years old and they do dry out with time. Many brands will work fine, but some won't please the cork sniffers.

 

[bigtomrodney]

Bias supply filters there, one does look dodgy. In the case of old filter caps you're as well changing them. They can rupture when they fail which is a lot more difficult to clean. Being that dried out caps wont sound like they did 45 years ago there's nothing to preserve as long as you put them away safely. Also as long as the form factor is right and they measure on spec you're fine. All of the brands that people corksniff about come from only 2-3 manufacturers. Considering their role in smoothing DC ripple i.e. do not carry signal their functionality in this regards is paramount. This is most certainly the one place where value determines effect on signal rather than some unknown magical quality.

 

[ES335TD]

Sorry guys,
I posted 2 more pics - not sure where they went:

 

[Humbuck]

Yeah, they're dimpled. I would probably change them.

 

[ES335TD]

So the JJ's will do the job? Any other suggestions? Thanks.

 

[bigtomrodney]

TAD, F&T, Mundorf, Ruby. The TAD rebranded caps are good value,got mine for €6.50 each.

 

[ES335TD]

Thanks everyone for the input, the convesation and the choices!

 

[shakti]

All DALYs are diimpled like that, even from the start. Nothing wrong with them.

It simply is not true that filter caps do not affect the tone. Two new filter caps which measure the same still won't sound and feel the same. I've experimented with this first hand many, many times. Like bluesforstevie, I've recapped old amps and wondered where the magic went. I've used NOS caps re-formed, and presto, the magic is there. I remember one particular amp where the preamp cap (a dual axial 32+32) was causing an intermittent buzz. Unfortunately, when it was swapped for a new F&T, all the fun in the mids went out with the cap...
Same thing withh new caps - two caps with the same rating can sound very different. RIFA axials, for instance, sound much much better IMO than F&T.

I would not change any of those caps, unless there are extraneous noises in the amp. If the amp has sat unused for 6 months or more it's a good opportunity to re-form the old filter caps by bringing up the voltage slowly. There are very simple methods to do this with only a 100k 2W resistor.

 

[bigtomrodney]

So a failing cap and a new one behaved differently? You don't say...

The difference is in the attack and it's down to the value of the cap. A well performing high valued new cap will be tight all around and it'll be most noticeable in the sharper bass and top end. However you have to recognise that a failing 40 year old cap is not how the amp sounded when new or even ten years old. If you like the sound of a failing cap, measure its value and use a new one close to that value. A capacitance meter is cheap.

 

[les strat]

You could always go NOS and put back what was originally in there. That's what I did with my '67 BFVR. A few were bad and needed replacing. Contact John Gurley (vintage amp guru) of Dixie Sound Works in Guntersville, Alabama. He will hook you up.

 

[Humbuck]

I've had older Marshalls re-capped and they absolutely came alive!

 

[yeti]

To the OP: I assume your amp tech told you this, right? From your tech's perspective I'd say this: Follow his advice or get a different tech. Do you really think that second-guessing his advice armed with "evidence" from an open forum is a good idea? Sounds to me that you don't think too highly of him in the first place. And just as someone can state that

It simply is not true that filter caps do not affect the tone

I can just as emphatically state that replacing Filtercaps with correct new ones will have zero audible effect. Who are you going to believe? good luck to you!

 

[J.D.]

Uugh, the old filter cap debate rears its ugly head yet again.

There's definitely 2 schools of thought here - and both are "right".

The vintage fans, occasional players, and collectors love old amps to be completely original and won't do alot of preventive maintenance anymore on a vintage, collectable piece. Sure if a component fails it gets replaced but probably won't be touched for fear of taking away its "mojo" or whatever.

The regular gig players and amp techs of working musician's are very wary of vintage equipment, especially amps, because old components like electrolytic caps fail at the damnest times. A small or potential tone tweak is a fair price to pay for reliability. Easy insurance on an old amp is to get new tubes and filter caps at regular intervals.

Who's right? Who cares. Live and let live :jim