New Dynakitparts 550v Quad Cap (OE was 525v) - EDITED

[MrCreosote]

I did the modern quad cap elimination in my Scepter only to find issues related to ground loops.

Needless to say, that stopped me dead in my tracks.

I regretted not putting a stock quad cap back in which also involved minimum effort.

With the explosion of new products for every conceivable need, Dynakitparts has a higher rated quad cap of 550v instead of the 525v.  It is $52.95.  http://www.dynakitparts.com/dynakit-products/capacitors/MULTI-SEC-ELECTROLYTIC-CAPA

While a 600v rating would be nice, the 550v sure makes the QC more tenable.

Opinions on using this improved QC?

Thanks in advance,
Tom

EDIT:

PS.  Any words of encouragement?  Should I stay the course and try to sort out my modern series cap pair elimination of the quad cap?  I see two issues/solutions:

• I used the existing wires in the harness to take now the unfiltered voltage to the various stages where I located the new capacitors.  With the QC, these wires carried filtered DC, so there is now an AC ripple wire in the harness which probably should be shielded?  I even bot the 600V rated shielding cable to do this.
• I grounded each new cap pair at the stage through their terminal strips which was very easy.  I could change those strips so that they are not grounded and then run a ground wire back to where the original ground was located.

Any other suggestions?

Thanks in advance,
Tom[/color]

[Soundmasterg]

I did the modern quad cap elimination in my Scepter only to find issues related to ground loops.

Needless to say, that stopped me dead in my tracks.

I regretted not putting a stock quad cap back in which also involved minimum effort.

With the explosion of new products for every conceivable need, Dynakitparts has a higher rated quad cap of 550v instead of the 525v.  It is $52.95.  http://www.dynakitparts.com/dynakit-products/capacitors/MULTI-SEC-ELECTROLYTIC-CAPA

While a 600v rating would be nice, the 550v sure makes the QC more tenable.

Opinions on using this improved QC?

Thanks in advance,
Tom

EDIT:

PS.  Any words of encouragement?  Should I stay the course and try to sort out my modern series cap pair elimination of the quad cap?  I see two issues/solutions:

• I used the existing wires in the harness to take now the unfiltered voltage to the various stages where I located the new capacitors.  With the QC, these wires carried filtered DC, so there is now an AC ripple wire in the harness which probably should be shielded?  I even bot the 600V rated shielding cable to do this.
• I grounded each new cap pair at the stage through their terminal strips which was very easy.  I could change those strips so that they are not grounded and then run a ground wire back to where the original ground was located.

Any other suggestions?

Thanks in advance,
Tom[/color]

The problem with the way Sunn ran the wires all in a loom like that is that the wires are running parallel to each other. With some connections like screen and plate, it makes no difference aside from capacitance increases...but stick a grid wire in there along with the others and you have a problem, generally consisting of oscillations, higher noise and hum, or both. Well that how Sunn did it.... With their layout, most amps are fine though due to the low gain and the localization of all the caps and grounds where they are. If you mount the caps by their respective stages and change your ground points, and use wires in the loom to run AC or even less filtered DC around, the grids will pick it up and amplify it as noise. Plenty of amps have had this mod done with success, but the key is to keep the cap locations and grounds at the same places they were stock. In the initial amp I did this way, I did locate the caps next to each stage they supplied, but I also put a full new isolated grounding system in the amp along with a ground lift switch. It was a lot of work to do and paid off in the end, but it isn't feasible for your application or needs I would guess.

To fix the problem you could experiment with trying to use shielded wire on the grids, but I would probably move the grounds to the same location as stock too. You can leave the caps where you put them but be sure to run any wiring at right angles to any grid wires for minimum noise and hum. Since you've already bought the parts and done the bulk of the work, I'd stick with what you have and make it work. It can be frustrating and time consuming, especially if you are not quite sure what you are doing, but you may learn something through the process, and your amp will be bulletproof when you get it fixed. Use stage isolation techniques to track down the source of the noise and hum. That will simplify things greatly for you once you can isolate the stage that the hum is being picked up in.

Greg

[MrCreosote]

I don't understand the practice of putting the caps at the stage rather than all at the power supply.

Spreading them all over the chassis spreads the capacitor feeds which have "pumping" 60 Hz noise in them.

Why not filter everything at the power supply and run clean DC to the stages?

[Isaac]

Because it doesn't necessarily stay clean. Putting a cap at the stage puts the DC at the stage at an AC ground. Theoretically, at least.

[Soundmasterg]

Putting the caps right at the stage they supply is the best way to do it for a number of reasons. However, in the Sunn, there are poor layout practices like most vintage amps. Unless you change those other things, keeping the caps localized to the power supply area and using the same grounds and DC feeds as a stock amp is probably the best approach if you don't plan to change the other things. It works fine if you do this. Sorry you have had problems with the mod....perhaps if you check over how you did the DC feeds to the stages and how you did the grounding, you can solve it? Treat it as a learning experience....

Greg