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-   -   SMPS stiffener cap? (http://www.diyaudio.com/forums/class-d/227524-smps-stiffener-cap.html)

Hikari1 11th January 2013 06:39 AM

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

Sch3mat1c 11th January 2013 01:19 PM

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

Hikari1 11th January 2013 09:24 PM

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?

nigelwright7557 11th January 2013 09:51 PM

Quote:

Originally Posted by Sch3mat1c (Post 3321079)
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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