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Old 11th January 2013, 05:39 AM   #1
Hikari1 is offline Hikari1  United States
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Default SMPS stiffener cap?

I am running a HifimeDIY T2 TK2050 w/ a sure 27V SMPS.

I've read a lot about adding a stiffener cap. I understand what it does but I am unsure how to implement it. The board already has a 10,000 UF cap on it, is adding a stiffener cap really needed or worth a shot?

Here's the amp:

Hifimediy T2 Mundorf

Here's the power supply:

SP-320-27 Mean Well | Mouser
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Old 11th January 2013, 12:19 PM   #2
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SMPS impedance is dominated by the control loop inside the power supply. Adding excessive capacitance will most likely unbalance it, making the impedance worse at some frequencies, or making it oscillate altogether. "Stiffener caps" have always been myths; even in automotive applications, it's hard to beat the internal impedance of a lead-acid battery.

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Old 11th January 2013, 08:24 PM   #3
Hikari1 is offline Hikari1  United States
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OK, understood. I do want to try adding a cap as it's easily reversible if I dont like it. You are probably right but it's worth a shot.

The back of the Meanwell is labelled:

+V, -V, ground, N, L

Right now the dc output is running to the amp from the +V and -V.

If I hook up a 50V, 2,200 uf cap between +V and ground on the power supply this should work, correct? The positive lead of the cap would go to +V and the negative lead to ground, correct?
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Old 11th January 2013, 08:51 PM   #4
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Quote:
Originally Posted by Sch3mat1c View Post
SMPS impedance is dominated by the control loop inside the power supply. Adding excessive capacitance will most likely unbalance it, making the impedance worse at some frequencies, or making it oscillate altogether. "Stiffener caps" have always been myths; even in automotive applications, it's hard to beat the internal impedance of a lead-acid battery.

Tim
Too much capacitance on the output of the SMPS can cause it to go into overload mode and switch off.
The smps will be running at hundreds of KHz so doesn't need big capacitors like a 50Hz system would.
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