| miguel2 |
Hi,
I'm running now a OPA549 based GC. It has a OPA627 based preamp with gain of 6.7. After it goes to a OPA549 inverted GC with gain of 3.2. Feedback resistor is 220k (SMD) and input is 68K. With this low gain I have a higher bandwith in the OPA549.
The psu is Pedja's discrete psu for GC, with +/- 22VDC rails. The preamp section also uses this psu, with regulators to get +/- 18VDC.
The sound of this thing is fast, crisp an articulate. For now I would say that it is a bit on the bright side, maybe after burning in it softens a bit. Bass is fast and punchy. I am quite happy with the result. Just need to get rid of the hum. Not much, but audible from the sitting position.
Miguel |
|
|
| demogorgon |
miguel:
how is the opa627 reacting to a gain of 6.7?
are you using multiple opa's? the data cheet say a max of 5 when it comes to gain.. |
|
|
| Alcaid |
| quote: | Originally posted by demogorgon
miguel:
how is the opa627 reacting to a gain of 6.7?
are you using multiple opa's? the data cheet say a max of 5 when it comes to gain.. |
That's wrong. It can handle much higher gain than that. It's stable down to unity, while the opa637 needs a gain of 5 or higher. Maybe your mixing things together. |
|
|
| miguel2 |
The datasheet only mentions the gain of 5 to the OPA637, because this one is not stable for lower gains. The OPA627 has the advantage of being stable for unity gain. This permits to use a cap to reduce high frquency noise to this gain of 1, while keeping audio frequencies at gain of 6.7. This helps to stabilize the power section.
Miguel |
|
|
| demogorgon |
| quote: | Originally posted by Alcaid
That's wrong. It can handle much higher gain than that. It's stable down to unity, while the opa637 needs a gain of 5 or higher. Maybe your mixing things together. |
I'v been known to do that from time to time, although thats what i'v read both in this forum and other places. |
|
|
| analog_sa |
| quote: | | although thats what i'v read both in this forum and other places. |
I'll be curious to know just one single source of your information. Not that i doubt the existence of ignorance and stupidity. |
|
|
| demogorgon |
| quote: | Originally posted by analog_sa
I'll be curious to know just one single source of your information. Not that i doubt the existence of ignorance and stupidity. |
It's just one of those things one pick up from time to time, and not remembering where i read it.
I was uninformed. my apologies are yours. |
|
|
|
