Modified ColdAMP SPS80

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fredos said:
Why you dont keep the original cap onboard to lower the ESR???

Keep leg of capacitor shorter than you can!

fredos

www.d-amp.com


Hi Fredos and others,

I was almost going to say the same thing. I would keep at least some capacitance on board so that the worst current/voltage spikes are kept on the PCB instead of going via those wires to the jensen caps and in the meantime emit rubbish. Maybe you want to get rid of those 2x3300uF caps per rail on board as you maybe afraid that the total capcitance is becoming too large? I have added an additional 10000uF ELNA cerafine offboard (per rail) (keeping the original caps), and the supply has no problem with that (no startup problems at least, have not checked full functionality when loaded with amps that give a varying load).

Another option could be to remove just one of the caps on the supply itself (so keeping one), or remove both of them and replace them with high quality smaller ones if the large total capacitance is a concern.

Best regards

Gertjan
 
Most people is vey happy with the sound using the SPS80 as it is from the factory, but if you want to add audiophile caps, I would also recommend to keep leads as short as possible and keep some capacitance on board, or EMI / regulation could be adversely affected, as Gertjkan and Fredos have suggested wisely.

Sergio
 
We don't recommend to add more than 10.000uF more per rail, in fact we think it is totally unnecessary to increase capacitance; have in mind that a switching power supply "refreshes" the capacitor charge at around 1000 times the rate of a linear PSU, so the "bare" onboard 6600uF per rail should be more than enough even for the most demanding loads.
Measured ripple at 800W load is around 1Vpp per rail with the standard caps. (!!!) Try to achieve that with a linear PSU ;-)

Best regards
 
"a switching power supply "refreshes" the capacitor charge at around 1000 times the rate of a linear PSU"

Very interesting; I hadn't fully appreciated that important advantage before - whereas a linear supply needs enough transformer and capacitance to keep up with current demand, the switching supply needs much less of the latter.
 
Hi,

These caps are on the SMPS though, I'd trust the module still has local bulk storage caps.. just like your nichicons.

BTW, going to post a pic of my Jensen supply tomorrow, freshly re-wired... you'd never know by the sound of it that they're paralleled at all, sounds just like a single cap supply, tight and perfectly coherent ;)
 
Connecting the board to better caps with long wire creates problems of EMI etc. But how about placing the whole thing in a metallic box? Will the box stop the generated EMI from affecting other components?

If this works, then I can use better caps while keeping other problems down
 
ackcheng said:
Connecting the board to better caps with long wire creates problems of EMI etc. But how about placing the whole thing in a metallic box? Will the box stop the generated EMI from affecting other components?

If this works, then I can use better caps while keeping other problems down

Cable runs from my SPS80 to power amps are approx. 20 - 30 cm,
with both amps and psu not boxed (just sat on a metal sheet). I don't have any problems with EMI/RFI, but there again, I don't have anything within 3 metres that would be affected.
 
ackcheng said:
Connecting the board to better caps with long wire creates problems of EMI etc. But how about placing the whole thing in a metallic box? Will the box stop the generated EMI from affecting other components?

If this works, then I can use better caps while keeping other problems down


Why don`t you just keep the original caps on the SMPS and add extra caps offboard (I added 10000uF ELNA Cerafine and kept the original caps onboard). Doing it that way, you will have less EMI issues as there will be not much HF current flowing in the wires to the offboard caps. If you really want to remove the caps on the SMPS, then why not remove just one of them, or remove both of them and put at least a smaller cap onboard, for example 470uF 100V cap to keep the HF currents on the board, not in the air. In my point of view it is always better to prevent the generation of EMI (by keeping some caps onboard) then trying to suppress it by putting the SMPS in a metal case. In fact, if you want to be really safe, you should do both, keep the caps onboard and put the thing in a metal case and add extra offboard caps if you like. I really think that removing those onboard caps is a bad idea.

Best regards

Gertjan
 
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