OPA549 on single supply

[bostjancek]

Hello !

Can anybody comment if the schematic for connecting the OPA549 on the single supply is correct ? If it is not please give me some advice how to make it right.

Cheers

 

[SSassen]

There's a few errors, look at your power supply connections. But more importantly why would you want to run with a single rail? You now have to use a coupling cap at both the input and output which isn't what I'd recommend for anything related to hifi. If you only have a 30-volts single rail you can also split it to 2x15 and settle on that.

Best regards,

Sander Sassen
http://www.hardwareanalysis.com

 

[bostjancek]

I have to put this amp in an guitar amp where I have only +30V DC. Can you tell me where are the errors at the power suply connection ?

Cheers

 

[mod_evil]

When do you not have a negative supply. The V- conector go to GROUND.

 

[carlosfm]

Hi bostjancek,

Yes, there are a few errors on your shematic.
The 4,700uf + 100nf caps are in series with the positive voltage rail (?!), they should be parallel from V+ to ground.
The input 2.2uf cap should be before the 47k cap.
And a suggestion: use a 4,700uf cap on the output, although not so important for a guitar amp.

 

[mod_evil]

Hi bostjancek,

Yes, there are a few errors on your shematic.
The 4,700uf + 100nf caps are in series with the positive voltage rail (?!), they should be parallel from V+ to ground.
The input 2.2uf cap should be before the 47k cap.
And a suggestion: use a 4,700uf cap on the output, although not so important for a guitar amp.

And... use a snuberized PSU ... I like the snubber that sound is more beautiful than the others schematics! I love your idea.

Thanks

 

[carlosfm]

And... use a snuberized PSU

You said that, not me.

 

[carlmart]

Can anybody comment if the schematic for connecting the OPA549 on the single supply is correct ? If it is not please give me some advice how to make it right.

One suggestion:

Try a different way for your virtual ground input connection. Increase the value of those resistors to something like 47K each, and don't connect that point directly to the + input, but through another 47K resistor. Then use a a 1uF capacitor from that middle resistor point to the V- rail. That should lower your ripple noise. Or use the parts used in the LM3886 datasheet for single supply application.

A single supply design has several flaws, the large output capacitor being the main one. So I don't think it will help much using a snubberized supply with it.


Carlos

 

[bostjancek]

Thanks for your comments. I realy don't know where my head was when I drown the given schematic.

Cheers !