[dyohn]

I'm building a DIY t-amp for fun and was thinking about power supplies.  I have a 12V/5A SMPS power supply designed for a flat panel computer monitor that I am thinking of using, but I know the output from these can be pretty noisy.  Has anyone added an L-C filter assembly to the output of this sort of supply?  Anyone think this would be a bad idea?  I have plenty of caps and inductors I could use, and I could build a capacitor array as large as necessary, I just don't want to damage the PS inadvertently.

Anyone have any guidance they can share?  Tank you!
David

[bluemike]

Ping Paul Hynes
He is a member here and very knowledgable when it comes to power supply assembly
He would be happy to answer your questions 

[Niteshade]

Try this place: http://www.astroncorp.com/

I think you'll be surprised. Amateur Radio dealers such as AES: http://www.aesham.com/  carry these things.

[dyohn]

Thank you for the suggestions.  I will try messaging Paul Hynes as well.

[slbender]

Hey David -

Try it - you may like it.  I use them in my tube amps, but that is a horse of another color, there I have to have a startup sequence similar to what launches an ICBM missile strike due to the wildly fluctuating impedance of tubes in the first 30 seconds from cold to hot... but T-Amps they should be a no-brainer.  I have a circa 2002 Made-in-China DTS and all that 5.1 Home Theater unit, filled with 6 channels of T-Amps, a CD/DVD player, full display and CD/DVD DAC decoder, with both digital and analog inputs and its all powered by an internal SMPS, not a power transformer in sight!!  So they made it work many years back..

-Steven

I'm building a DIY t-amp for fun and was thinking about power supplies.  I have a 12V/5A SMPS power supply designed for a flat panel computer monitor that I am thinking of using, but I know the output from these can be pretty noisy.  Has anyone added an L-C filter assembly to the output of this sort of supply?  Anyone think this would be a bad idea?  I have plenty of caps and inductors I could use, and I could build a capacitor array as large as necessary, I just don't want to damage the PS inadvertently.

Anyone have any guidance they can share?  Tank you!
David

[BillB]

I think you would be adversely affecting the performance of the SMPS. If you read about what a SMPS does (excerpt quoted)

"Switching creates a rectangular waveform that typically goes to the primary of the transformer; typically several secondaries feed rectifiers, series inductors, and filter capacitors to provide various DC outputs with low ripple."

You will see that this is done internally. What would you gain by lessening ripple in a power supply that already has low ripple.

Seems like you would add unnecessary load.

Try it though...no harm in trying right? 

[dweekie]

I've had some luck with adding LC filters to my smps.  I found something as simple as a 22uh inductor makes a difference.  In a pair of smps I'm using right now on some class D amps, I only have a Siemens Sikorel attached to the output with very good results overall (no inductor).  Here's a link to a commercial product that seems to be designed to do what you are intending to do.

http://www.audio-magus.com/12_volt_Power_filter_Audiomagus_powercleaner_p/pf1.htm

[dweekie]

Try it though...no harm in trying right? 

Unless you add too much capacitance at the output for the SMPS to handle...    I think I broke atleast a few things by telling myself there's no harm in trying

It'll be SMPS dependent, but I've read of people using 40k uf or more without any issues.  Actually, I've yet to read about anyone actually having an issue, but everyone seems to mention that possibility with high capacitance at the output......    I've used about 20k on mine, but it'll be SMPS dependent so that really has no relavence I suppose.

[dweekie]

duplicate, sorry.

[BillB]

Ok yeah, something low like that should be fine...I was thinking big tube values like 1H+