To get a symmetrical PSU u can use something like meanwell DCW, look here:
https://diyaudioprojects.com/Chip/Opamp-Phono-Preamp/
https://diyaudioprojects.com/Chip/Opamp-Phono-Preamp/
Cool. Curious what frequency you tuned the LC filter at - did you hear noise at a specific spot? - and what you used for that. In my case, I can literally kill everything above about 5k if I need to and it helps. I've made RC filters but not LC.
Most OP amps have reasonable PSRR at lower freq but struggle with the high freq noise, so the LC filter was set ~500Hz. The linear regulators PSRR will help but they also struggle to reject higher freq supply noise. I added the LC because of what I saw on a scope and how some of that HF noise appeared on the OP amp outputs. It did help lowering the audio background noise but the difference was small. A lot of the noise is outside of the audio range.
I think that one is more powerful. The one I posted a pic of is good for about 100mA.
Follow up:
The $8 power supply in the Original Post (from here on ebay) works great. The noise level is very good - better than 85db I would say, ballpark, looking at the scope. Seems to me there is no need for a power supply better than this for a bass amp.
Unfortunately I have not been able to fix the power amp section of this 1984 Gallien-Krueger 200RB, but it's good to have the classic GK preamp section to just plug into another power amp.
Thanks all for the comments and discussion. Never let gear die.
The $8 power supply in the Original Post (from here on ebay) works great. The noise level is very good - better than 85db I would say, ballpark, looking at the scope. Seems to me there is no need for a power supply better than this for a bass amp.
Unfortunately I have not been able to fix the power amp section of this 1984 Gallien-Krueger 200RB, but it's good to have the classic GK preamp section to just plug into another power amp.
Thanks all for the comments and discussion. Never let gear die.
It is possible to connect two +15 V wall warts in series and get ±15 V. But note that not all wall warts are suited for this. Many laptop bricks, for example, have the output ground referenced to mains ground (or protective earth). So if you connect two in series you short circuit the one intended for -15 V.
If the wall wart meets electrical safety Class II and has a two-prong connection on the input you can usually connect two of them in series.
You can use a buck converter as an inverter, though. That allows you to put +15 V in and get -15 V out. See more here: https://www.analog.com/en/design-no...rter-from-a-buck-stepdown-dcdc-converter.html
Personally I'd use an SMPS that provides the ±15 V that you're looking for. RECOM makes a nice one. RAC10 is the product number if I recall correctly.
Tom
If the wall wart meets electrical safety Class II and has a two-prong connection on the input you can usually connect two of them in series.
You can use a buck converter as an inverter, though. That allows you to put +15 V in and get -15 V out. See more here: https://www.analog.com/en/design-no...rter-from-a-buck-stepdown-dcdc-converter.html
Personally I'd use an SMPS that provides the ±15 V that you're looking for. RECOM makes a nice one. RAC10 is the product number if I recall correctly.
Tom