I think you are going down the wrong rabbit hole. Your PSU LM317 regulator is probably not the culprit here. I told you in your other thread (in the Tube section) that my same 12AU7 amp runs dead quiet also using a simple LM317 regulator circuit (and I gave the schematic from Pete Millett), BUT – I feed the regulator with a 19V laptop smps. You are most likely dealing with a ground loop issue and unless you describe your complete setup it will be very difficult to solve your problem here. Another cause could be a USB connection if you are using a computer as source. So, give us more details maybe.
I was using veroboard with the PSU jumped to a breadboard with the amplifier circuit. I just wanted to make sure I get a really solid design and can veroboard that before I start rebuilding again. I will definitely give the Pete Millet design and post the results of that here. Do you think the SMPS has anything to do with the issue at all? I plan to use the design I have in post #39 as my next build to see if that fixes the problem. I am sure my veroboard layout had to do with some of the problem.
I will build this one as well and see how that goes.
Check out the section on filtered output ripple injection in this document from TI. https://www.google.com/url?sa=t&sou...FjAAegQIBRAB&usg=AOvVaw2f05XYiI0hOqUQXn2hjJ-g - slva653 TI
Another option is using a bypass capacitor on either of the feedback resistors to effect HF or LF ripple gain. This calculation may require delta-wye.
Another option is using a bypass capacitor on either of the feedback resistors to effect HF or LF ripple gain. This calculation may require delta-wye.
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> section on filtered output ripple injection
Wouldn't it be simpler to build a boiler, a steam turbine, and a DC generator?
Or a very large fire and thousands of thermocouples? (It's how Ohm's Law was developed.)
Wouldn't it be simpler to build a boiler, a steam turbine, and a DC generator?
Or a very large fire and thousands of thermocouples? (It's how Ohm's Law was developed.)
Try this: Simple Voltage Regulators Part 2: Output Impedance
The last but 2nd fig at page bottom.
TNT provided a better layout on the LM317 output, which removed ground pollution.
The last but 2nd fig at page bottom.
TNT provided a better layout on the LM317 output, which removed ground pollution.
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😀 Or, build a battery charger and just run the amp from rechargeable batteries.
Yes – because of the grounding scheme. But, there is nothing magical about switched mode power supplies and you can build one yourself if you wish. They are so cheap and abundant it is probably not worth it. Most folks around here would probably use a linear supply for such an application. So, there are alternative options to supplying power to your amp, and as you have discovered – every audio device you are going to build in future needs the correct and a quiet power source, be it your next headamp, power amp, preamp, dac and even a Raspberry Pi if you use one. I have been using what is called Capacitance Multipliers lately with great success. I use them (feeding from SMPS supplies) for my power amps, preamps, DAC and Raspberry Pi streamer. There are many designs on this forum, but here is one for example that is suitable for running your headamp as quiet as a church mouse:
GB for Simple Cap-Mx Regulated Low-Noise PSU
I would suggest you do a simple test and report back:
1. With your amp connected but no music playing – turn up the volume. Do you hear a buzz and does it get louder as you turn up the volume?
2. Now unplug the input signal cable and repeat the above. Do you still hear the same happening?
If your amp is quiet after you unplugged the music source, then your LM317 regulator is NOT to blame for the buzz. It is most likely the circuitry feeding the regulator, and more specifically the grounding scheme that is causing a ground loop issue. Unfortunately, I am not knowledgeable to help you with that.
+1
3. Test with only one channel connected.
Posting some photos of your build will help us to help you.
3. Test with only one channel connected.
Posting some photos of your build will help us to help you.
Help is not far away. If you are looking for a quiet LM317 implementation, try this maybe:
D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.
D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based V.Reg.
Amp is up and running sounding wonderful even as a prototype with wires running everywhere as it is not in a case yet.
That's great news! 
I'm not LT Spice-expert enough to know what the simulator will think of your "12V" and "-12V" labels on the transformer secondary leads, but the resulting story it tells may not be what you think.
If super-silence is what you seek, I'd also recommend replacing the 0,01 uF caps across the MURS120's. Mark's Quasimodo and Cheapo-modo projects on this site are long-running, well-supported, and work great! It'd be worth borrowing an o'scope to do it, if you need to.
Regards
I'm not LT Spice-expert enough to know what the simulator will think of your "12V" and "-12V" labels on the transformer secondary leads, but the resulting story it tells may not be what you think.
If super-silence is what you seek, I'd also recommend replacing the 0,01 uF caps across the MURS120's. Mark's Quasimodo and Cheapo-modo projects on this site are long-running, well-supported, and work great! It'd be worth borrowing an o'scope to do it, if you need to.
Regards
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That's great news!
I'm not LT Spice-expert enough to know what the simulator will think of your "12V" and "-12V" labels on the transformer secondary leads, but the resulting story it tells may not be what you think.
Regards
That was just me being lazy and calling out what I wanted the DC value to be. Upon checking my DC voltage out of the PSU it indeed was regulated down to 12.6VDC.