Help needed with Capacitors

perrin21

Member
2011-09-25 11:52 am
I have a Myriad MA240 power amplifier i would like to replace and upgrade the main capacitors inside. However, the capacitors are 22mm wide and there is no room for a wider capacitor which appears to severely limit the choice i have for replacements. The capacitors that are inside currently are Nichicon LS 63V 4700uF . Can anyone recommend a significantly better capacitor to replace the 7 inside? Assume for now that money is no object and size is the main restriction. What do you suggest that has better specifications?

I am also looking for some suggestions on other upgrades for this amplifier as ive noticed there are some poor quality components inside that could be easily replaced such as the Potentiometer switches (1 already crumbled when i tried gently adjusting the bias). Who makes the best quality 5mm 500R potentiometers for the bias?

Here are some pictures of the board.
 

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Just saying - the vent on this kind of caps is on the bottom. You cannot tell by the top whether they might have vented at all.

Assuming that the amp has just seen normal domestic use over the last ~20 years and that they aren't from some known-problematic series, they are very likely to be just fine still. If in doubt, ask an ESR meter.

If you wanted, you could add at least 1 more pair of identical caps, but at almost 2x 20000 µF stock this is really getting into diminishing returns territory.

A none-too-old quality power amp is rarely the most promising target for mods. (And if so, it has generally to get far more involved than just throwing parts at it.) Speakers with even dispersion, room correction, room treatment - those are the big guns.
 

perrin21

Member
2011-09-25 11:52 am
Just saying - the vent on this kind of caps is on the bottom. You cannot tell by the top whether they might have vented at all.

Assuming that the amp has just seen normal domestic use over the last ~20 years and that they aren't from some known-problematic series, they are very likely to be just fine still. If in doubt, ask an ESR meter.

If you wanted, you could add at least 1 more pair of identical caps, but at almost 2x 20000 µF stock this is really getting into diminishing returns territory.

A none-too-old quality power amp is rarely the most promising target for mods. (And if so, it has generally to get far more involved than just throwing parts at it.) Speakers with even dispersion, room correction, room treatment - those are the big guns.

Thanks for your reply. I plan on replacing the caps in all 4 of my amps as they are all getting old and i want to ensure they are performing at their best. Is it as easy as just adding another 2 capacitors to the existing slots to increase capacity? What is the benefit? I have noticed the amps sound a bit low on power recently so i felt its time for some general maintenance. I already have room correction etc in my AV system and Nam speakers.
 

mchambin

Member
2011-03-13 8:21 pm
I understand, you will change the caps and add two at unpopulated places ( for each amp ).
What benefit ?
The more capacity, the better, theoretically giving better bass ( less droop at very low frequencies ).
I saw a trend on Panasonic FR caps. A same capacitor value ( uF, voltage ) comes with variants about diameter, lenght, lead spacing. The larger the volume, the lower the ESR.
 

perrin21

Member
2011-09-25 11:52 am
I understand, you will change the caps and add two at unpopulated places ( for each amp ).
What benefit ?
The more capacity, the better, theoretically giving better bass ( less droop at very low frequencies ).
I saw a trend on Panasonic FR caps. A same capacitor value ( uF, voltage ) comes with variants about diameter, lenght, lead spacing. The larger the volume, the lower the ESR.

The Panasonic's won't fit. 22mm diameter is my limit although I don't have a restriction on height.
 
I would say the capacitors were fine, the plastic does lift but not because the capacitors are bulging, the plastic lifts with age. This type of capacitor bulge underneath if the vent gets blocked.


I agree.
There is nothing physically wrong with those caps.
People have gotten SO inclined to start changing caps ever since some nitwit nervous nut posted something way back online.
It never stops.... and it really should.
 

perrin21

Member
2011-09-25 11:52 am
I agree.
There is nothing physically wrong with those caps.
People have gotten SO inclined to start changing caps ever since some nitwit nervous nut posted something way back online.
It never stops.... and it really should.

I can genuinely say that 4 of the caps are bulging to the touch underneath the top cap. They may look ok but even my wife picked out the offender's. Regardless they are all being removed and swapped when I settle on suitable replacements. I was hoping for some suggestions from experience bout what sounds the best out of what fits. I may have missed something from a brand I don't know. I replaced the potentiometers today and set the idle voltage, that made a difference in itself as the old pot crumbled.
 
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