Another, less popular, but very effective way to moddify your amp.

[vivanchenko]

I just changed electrolitic filter caps in my Traynor YBA 4 and was greatly satisfied with how this changed the way the amp sounds.

I am not sure how different makes change tone, but different values do make as much of a difference as different speakers or tubes. Even more than that. It can completely change the character of your amp, for better or for worse. Replacing filler caps with stock values will not change much, unless the originals drifted out of speck. Using caps with greater values (approximately by 20%) will increase headroom and make your amp sound louder (note this, you, high headroom seekers).

Going down by approximately 20% will decrease headroom, add more compression and make your amp sound considerably crunchier and rawer.

Early Marshals had undersized filter caps and, as I understand now, this forms a very big part of Marshall sound.

My vintage YBA has a classic Bassman circuit and it had two two section 40 uF filter caps which I replaced with two two section 32 uF F&Ts (a classic Marshall value) and I was blown away by the change! Now my Traynor sounds very noticeably thicker, rawer, with much more harmonic content and sustain. This also knocked off a couple of decibels from my amp which is a very welcome change, because my YBA is so loud it can kill. Now I can can get into crunch territory without getting as loud as I had to previously.

Also, it is worth buying more expensive caps at least because they have much tighter tolerances. That is they can be the same on paper, but in real life they are very different. I measured over a dozen of cheap Chinese electrolytics and they all were like 50-120% off the specified value. The 32 uF F&Ts which I ordered all measured within 32-34 uF.

In a way I was inspired by this video (but not only) : https://www.youtube.com/watch?v=WPzljItlxN4

 

[Scott_F]

Re: Another, less popular, but very effective way to moddify your amp.

A lot of amps I read about folks building, they tend to up the filtering a bit. I hardly ever hear about lowering them. Good food for thought.

 

[PFDarkside]

Re: Another, less popular, but very effective way to moddify your amp.

Conceivably if you go too low, you'll start to get noise from rectifier ripple. Also, I'd imagine a tube rectifier would be better if you are looking for power supply sag, diode rectification like on Marshalls tighten the response.

 

[Scott_F]

Re: Another, less popular, but very effective way to moddify your amp.

Same thing on a choke

 

[PFDarkside]

Re: Another, less popular, but very effective way to moddify your amp.

Yep!

Cool idea, thanks for sharing.

 

[crusty philtrum]

Re: Another, less popular, but very effective way to moddify your amp.

A valve (tube) rectifier will dictate how big the value of the first filter cap can be (ususally not more than 50-60 uF), although s/s rectification does not impose such limits.

 

[vivanchenko]

Re: Another, less popular, but very effective way to moddify your amp.

Conceivably if you go too low, you'll start to get noise from rectifier ripple. Also, I'd imagine a tube rectifier would be better if you are looking for power supply sag, diode rectification like on Marshalls tighten the response.

Yes, I am in the middle of a JTM 45 project now. Got to have that tube rectifier goodness. Quality hand-wired project amps tend to sound just as good or better than modern Marshall reissues IMO. They are also much easier to upgrade with higher quality parts. I am using a lot of vintage parts, including output transformer (actually, it's a Univox 50 W output transformer).

 

[Myaccount876]

Re: Another, less popular, but very effective way to moddify your amp.

You do realize that the values the manufacturer selects for filter capacitors isn't just random guesswork, right? Those values were selected for a reason. Playing around with the values too much can introduce a lot of noise, and AC ripple, and if you're not filtering enough of the ripple, you risk damage to the power transformer. If you want more or less headroom, there are much better (and safer) mods to attain that goal. And just because you can get away with altering the filter cap values on some amps doesn't mean you can do the same for all other amps. Proceed at your own risk. People shouldn't be casually swapping filter cap values like they would speakers or tubes. It's a less popular mod for a reason.

 

[LLL]

Re: Another, less popular, but very effective way to moddify your amp.

I just changed electrolitic filter caps in my Traynor YBA 4 and was greatly satisfied with how this changed the way the amp sounds.

I am not sure how different makes change tone, but different values do make as much of a difference as different speakers or tubes. Even more than that. It can completely change the character of your amp, for better or for worse. Replacing filler caps with stock values will not change much, unless the originals drifted out of speck. Using caps with greater values (approximately by 20%) will increase headroom and make your amp sound louder (note this, you, high headroom seekers).

Going down by approximately 20% will decrease headroom, add more compression and make your amp sound considerably crunchier and rawer.

Early Marshals had undersized filter caps and, as I understand now, this forms a very big part of Marshall sound.

My vintage YBA has a classic Bassman circuit and it had two two section 40 uF filter caps which I replaced with two two section 32 uF F&Ts (a classic Marshall value) and I was blown away by the change! Now my Traynor sounds very noticeably thicker, rawer, with much more harmonic content and sustain. This also knocked off a couple of decibels from my amp which is a very welcome change, because my YBA is so loud it can kill. Now I can can get into crunch territory without getting as loud as I had to previously.

Also, it is worth buying more expensive caps at least because they have much tighter tolerances. That is they can be the same on paper, but in real life they are very different. I measured over a dozen of cheap Chinese electrolytics and they all were like 50-120% off the specified value. The 32 uF F&Ts which I ordered all measured within 32-34 uF.

In a way I was inspired by this video (but not only) : https://www.youtube.com/watch?v=WPzljItlxN4

:naughty:

One thing I noticed right away back in '03 or so when I was tinkering with my Marshall JTM45RI...

The stock filtering was high (poweramp for example was 50+50uF IIRC)... dropped that down to mid 60's JTM45 spec with 16+16uF pre & 32+32uF power... and instant touch sensitivity and sag. 3d-ish quality.

In fact, the entire stock circuit was a fuggin' joke compared to the original 60's; I replaced the entire thing.

Totally agree with your mod (for the experienced amongst us) - IMO, it kind of changes the tone, but for me, more the feel of the amp.

 

[LLL]

Re: Another, less popular, but very effective way to moddify your amp.

You do realize that the values the manufacturer selects for filter capacitors isn't just random guesswork, right? Those values were selected for a reason. Playing around with the values too much can introduce a lot of noise, and AC ripple, and if you're not filtering enough of the ripple, you risk damage to the power transformer. If you want more or less headroom, there are much better (and safer) mods to attain that goal. And just because you can get away with altering the filter cap values on some amps doesn't mean you can do the same for all other amps. Proceed at your own risk. People shouldn't be casually swapping filter cap values like they would speakers or tubes. It's a less popular mod for a reason.

What in the Wide World of Sports are you talking about? :dunno:

I take it you've never modded or built an amp before.

Those of us who have know how much (or how much less) filtering is necessary for certain tonal results.

Know the manufacturer's rules, then break them.