I use a pair of Mean Well SMPS bricks in my DIFF PRE 8x2 differential preamp. You can see the performance plots on my website.
I use a CLC filter on the output of the switching modules. At least with modern parts, that provides plenty of ripple attenuation to ensure good performance of the overall preamp.
Not to knock your choice of opamp, but newer parts, such as the OPA1612, LME49720, etc. have much higher PSRR than the humble NE5532 and are worth considering in your application.
The trick with CLC filters is to pick the components such that you get meaningful attenuation at the switching frequency of the SMPS without causing (too much) peaking in the filter response. Ideally, you would optimize the filter for the lowest supply impedance as well.
I tend to shy away from CRC filters as they raise the supply impedance by 'R'.
In my HP-1 headphone amp, I use a pair of Mean Well switchers with a CLC filter and a pair of LM317/LM337 linear regulators. That provides stellar performance as well. You can see the plots here: HP-1: Ultra-High End Headphone Amplifier
Tom
I don't know that specific supply, so I can't make a specific recommendation. If the switching frequency is 65 kHz, you'll want decent attenuation at that frequency. You'll want the filter bandwidth to be at least as wide as the SMPS's regulation bandwidth and you'll want to avoid peaking in the filter response.
To make a specific recommendation, I would need to know the regulation bandwidth of the supply. If I was to take a guess, I'd say mid-kHz range, maybe. So design a filter with that cutoff frequency and minimal peaking that gives you the best attenuation as you can get at 65 kHz. You'll need to include the parasitics (DCR/ESR) of the chosen components in your design. You'll also need to make sure that the inductor won't saturate at the output current you intend to draw.
Tom
To make a specific recommendation, I would need to know the regulation bandwidth of the supply. If I was to take a guess, I'd say mid-kHz range, maybe. So design a filter with that cutoff frequency and minimal peaking that gives you the best attenuation as you can get at 65 kHz. You'll need to include the parasitics (DCR/ESR) of the chosen components in your design. You'll also need to make sure that the inductor won't saturate at the output current you intend to draw.
Tom
I would suggest that rigging up 32V from a battery supply is likely to be a lot easier than the learning curve you are going through from post #21 onwards.
Check if the amp module can operate with 36Vdc (or even 24V), and if so then use 3x 12V (or 5-6 x 6V) small vrla batteries (4-7Ah small monobloc batteries are very plentiful from any old small-medium domestic/commercial UPS). If 36V is too high, then series up about 10 1N400x and insert in series to drop the voltage a bit.
Just saying ...
Hi SemperFi,
Can you provide more details about this? I would like to use a single SMPS for multiple amps, each of which have their own onboard bulk capacitance, and presently there is way too much capacitance for the SMPS. If I can avoid having to add more SMPS units to power these amps, I would be quite happy.
check this thread out, I have built a few of these filters, they are pretty amazing. PO89ZB , an inline DC filter for SMPS wall warts . Preamps, HPA, Korg NuTube, etc
Check post 40, I posted pre/post filter comparisson.
Check post 40, I posted pre/post filter comparisson.
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