Amplifier Circuit Simulation Services

[Yamaha5000]

One thing you can try is to look at the output of the preamp to see if it's clean.

From post #59

 

[Yamaha5000]

@LesE I just checked the pre out again with the unit buttoned up:

 

[LesE]

Looks like the preamp right channel is weaker.

 

[Yamaha5000]

Looks like the preamp right channel is weaker.

Appears to be on the Tone Board

 

[LesE]

Appears to be on the Tone Board

So if you want to continue testing the amplifier, you can either go straight into the MAIN IN or continue using AUX and adjust the balance slightly until the preamp output levels are equal.

 

[Yamaha5000]

Main IN to SP Out

 

[LesE]

That looks better. The right channel THD is a little worse than the left channel but it's still pretty good. I'd back off a little to the rated output power (100W) to see what that looks like. The worst case THD should be at 20kHz where I believe the spec is 0.1%.

 

[Yamaha5000]

That looks better. The right channel THD is a little worse than the left channel but it's still pretty good. I'd back off a little to the rated output power (100W) to see what that looks like. The worst case THD should be at 20kHz where I believe the spec is 0.1%.

Thoughts on the 60hz?
Preamp looks good on it's own, Main Amp looks good on it's own (THD only, everything else looks not so good). Why together THD doesn't look good?

 

[LesE]

Thoughts on the 60hz?

Try removing all input cables as well as the dummy loads and look at the speaker output with the analyzer. It could be a ground loop or interference. Is there any electrical equipment or florescent lights nearby? It could possibly be from the power transformer. Is the 60 Hz audible at normal listening levels? Keep in mind that you will probably see some 60 Hz no matter how hard you try to get rid of it. I believe that some of the display shots in the tutorial document also showed some 60 Hz. It's also possible that the analyzer test leads are picking up the 60 Hz.

Preamp looks good on it's own, Main Amp looks good on it's own (THD only, everything else looks not so good). Why together doesn't look good?

I can't quite explain that one. The preamp harmonics are low enough that they shouldn't have a large affect on the total THD when the pre amd main are connected together.

 

[Yamaha5000]

Keep in mind that you will probably see some 60 Hz no matter how hard you try to get rid of it.

Thoughts on that denoiser PS that I posted?

look at the speaker output with the analyzer

I think that will overload the input of the QA

It could be a ground loop or interference. Is there any electrical equipment or florescent lights nearby?

No fluorescent lights nearby
The main 240V 200A service disconnect is close by. Loopback test doesn't pick it up.

It's also possible that the analyzer test leads are picking up the 60 Hz.

Test leads are RG174 with RCA's and adapters for direct connection.

 

[LesE]

Thoughts on that denoiser PS that I posted?


I think that will overload the input of the QA


No fluorescent lights nearby
The main 240V 200A service disconnect is close by. Loopback test doesn't pick it up.

Test leads are RG174 with RCA's and adapters for direct connection.

Sorry, I didn't have any other suggestions. Perhaps others will have some ideas.

 

[Yamaha5000]

I believe that some of the display shots in the tutorial document

Did you pick up anything in the tutorial about why I am having issues on conducting the Automated Test "PWR THD VERSUS POWER"

 

[LesE]

Did you pick up anything in the tutorial about why I am having issues on conducting the Automated Test "PWR THD VERSUS POWER"

I only skimmed through it quickly. Perhaps you can check with the author.

 

[Yamaha5000]

D-Noizator: a magic active noise canceller to retrofit & upgrade any 317-based VReg

Hello optimationman, How is it going with your project with / without denoiser? Did you replace a lm317/337 with a super regulator and made listening test? Best regards

www.diyaudio.com

See post #1 and #1008

 

[Yamaha5000]

https://www.diyaudio.com/community/attachments/ac-psu-v2_2020-07-23-zip.868774/

 

[Yamaha5000]

@LesE My question is to create the Yamaha Power Supply in LTspice and compare it to the D-Noizator

 

[LesE]

@LesE My question is to create the Yamaha Power Supply in LTspice and compare it to the D-Noizator

First things first. Let's finish with the power amp and then we'll see but I only have a very limited amount of time that I can devote to this.

 

[Yamaha5000]

First things first. Let's finish with the power amp and then we'll see but I only have a very limited amount of time that I can devote to this.

I was thinking since the D-Noizator LTspice file was given that it may be a more simple request.

 

[Yamaha5000]

For Class A/B operation at rated power, the original design gives a THD of 0.022696%. Adding a current mirror to the input differential amp reduces the THD slightly to 0.011277%. A initial reconfiguration of the voltage amplifier to a Darlington configuration dropped the THD to 0.003198%. That's almost an order of magnitude.

I have transplanted the bias circuit from the CA-1010 into the CA-1000 design but more work is required. I'm not seeing any additional improvement at this point but I may have to simulate the CA-1010 in order to fine tune the modified circuit in the CA-1000.

Any additional progress on these items?

 

[LesE]

Any additional progress on these items?

Actually, I was hoping that I would be able to wrap this up yesterday but after literally hundreds of THD runs, I found that the change of drivers was causing problems. So now it's back to the drawing board.