odysseybmx414 said:figured it out
You are on the correct path for the OPAs, because they work (and sound) much better at low gains.
But I would not use unity gain, or you will be limited to the voltage rails of the gainstage. Is something around 10 Watts ok for your application?
Here's some suggestions, or the way I would do it:
- Remove C1, the buffers U2 and U3, C3, and C4.
- Bias the OPA627 to class-A at around 10ma.
- Reduce the gain of the OPA627 to 5 and use a gain of 4 on the OPA549.
You'll have a very transparent amp, but beware, do not try to smoothen things out by 'over-engineering' because the problem may come from the components before the amp: pre and/or source.
PS: a gain of 21 on the OPA627 is way too much, for use with line-level sources.
odysseybmx414 said:correction: that is not a opa627 its a opa27
Ahh...
OPA134, then. And forget the biasing.
BTW I've just figured out that nasty 200k pot.
Use a much lower value, 10 or 20K.
Also, you better use a resistor after C1 and C3 to ground.
47K is fine.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
- Home
- Amplifiers
- Chip Amps
- opa549 as unity gain