Is it OK to add a large bank of caps outside the amp?

mattjk · 14th November 2004, 10:50 PM

I built an amp in a small case, but I want to add a couple of 82000uf caps, an addition to the 2 10000uf caps that are inside.

Are there any negatives to this? I've seen some tube amp manufacturers do this.

Matt

quasi · 14th November 2004, 11:21 PM

There should be no problem with this provided you do it in a safe manner i.e. housed. Depending on the amp the voltage across the capacitors could be lethal. Make sure the capacitors working voltage is high enough.

The only concern would be whether your rectifier could handle the larger instantaneous load while these charge up so I would check this.

Place an additional discharge resistor across them too.

Cheers

mattjk · 14th November 2004, 11:27 PM

thank you for your reply.

I plan on incorporating a manual soft start switch, but for now, I leave the amp on all the time, and turning it on doesn't seem to be a problem.

Thanks!
Matt

EWorkshop1708 · 15th November 2004, 03:19 AM

I'm glad I found this thread!

That just answered a question I had about the amp I just made.

I plan on having larger caps external from the PCB so they don't take up precious circuit board space. However, they will be inside the enclosure.

I guess the wires need to be thick for the amps to get the best peak current from the externally mounted caps.

AndrewT · 15th November 2004, 03:18 PM

Hi e1708,
Consider using thinner wires to connect the extra bank of caps into the board.
The resistance will create a CR filter and a few hundred milliohms here might better suit your needs.
Then the onboard caps should be sized to meet the short term peaks.
regards Andrew T.

14th November 2004, 10:50 PM	#1
mattjk diyAudio Member Join Date: Aug 2004 Location: Huntington Beach, Ca	Is it OK to add a large bank of caps outside the amp? I built an amp in a small case, but I want to add a couple of 82000uf caps, an addition to the 2 10000uf caps that are inside. Are there any negatives to this? I've seen some tube amp manufacturers do this. Matt

14th November 2004, 11:21 PM	#2
quasi diyAudio Member Join Date: Sep 2004 Location: Adelaide, Australia	Re; external capacitors There should be no problem with this provided you do it in a safe manner i.e. housed. Depending on the amp the voltage across the capacitors could be lethal. Make sure the capacitors working voltage is high enough. The only concern would be whether your rectifier could handle the larger instantaneous load while these charge up so I would check this. Place an additional discharge resistor across them too. Cheers __________________ http://sites.google.com/site/quasisdiyaudiosite/

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14th November 2004, 11:27 PM	#3
mattjk diyAudio Member Join Date: Aug 2004 Location: Huntington Beach, Ca	thank you for your reply. I plan on incorporating a manual soft start switch, but for now, I leave the amp on all the time, and turning it on doesn't seem to be a problem. Thanks! Matt

15th November 2004, 03:19 AM	#4
EWorkshop1708 diyAudio Member Join Date: Nov 2004 Location: Florida	I'm glad I found this thread! That just answered a question I had about the amp I just made. I plan on having larger caps external from the PCB so they don't take up precious circuit board space. However, they will be inside the enclosure. I guess the wires need to be thick for the amps to get the best peak current from the externally mounted caps.

15th November 2004, 03:18 PM	#5
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi e1708, Consider using thinner wires to connect the extra bank of caps into the board. The resistance will create a CR filter and a few hundred milliohms here might better suit your needs. Then the onboard caps should be sized to meet the short term peaks. regards Andrew T.

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