Just finished one channel of my new OPA549 and have to say I don't like it at all. I'll say that it sounds good at low volumes but once you start getting loud with it, it distorts too badly for my taste.
The LM1875 is far better choice in my opinion. Still my chip of choice.
The LM1875 is far better choice in my opinion. Still my chip of choice.
Here is why the distortion. Had gain set at 18. Didn't think it was loud enough so changed feedback resistor with 1 meg resistor giving me a gain of 100. I still had adjustment through volume control. The distortion was from setting the gain too high and cranking it up. I thought I'd see what I could get this chip to do by setting the gain higher.
Set the gain back to 18 and all is well. Problem is I was expecting alot more volume from this chip.
Power supply is +- 25 at 4 amps. Should be OK.
Heatsink seems to be carrying itself, it isn't shutting down from being too hot.
Unless anyone has ideas on anything I can do to make it louder I think the next project will be bridging two together.
Looks like I LOVE IT LOUD.
Thanks everyone
Set the gain back to 18 and all is well. Problem is I was expecting alot more volume from this chip.
Power supply is +- 25 at 4 amps. Should be OK.
Heatsink seems to be carrying itself, it isn't shutting down from being too hot.
Unless anyone has ideas on anything I can do to make it louder I think the next project will be bridging two together.
Looks like I LOVE IT LOUD.
Thanks everyone
theChris said:you'd have to power the opa549 and 637 off of equal rails. the opa637 is limited to +-18V, while the opa549 can go much higher.
You're right.
OPA552 seams perfect for this job.
Check it out.
Re: Somethig different
Carlos,
This is very interesting, an opa637 with a gain of 20-22? Then a 549 in unity gain... is it possible?
JojoD
carlosfm said:Here's a good opportunity to make something different.
OPA549 as a buffer, with a gain stage before it.
OPA637 biased into class-A?
Carlos,
This is very interesting, an opa637 with a gain of 20-22? Then a 549 in unity gain... is it possible?
JojoD
carlosfm said:Yes, but you can't go higher than +/-18v PSU voltage.
Other op-amps can handle more.
How about +/-18v for the 637 and +/-25v for the 549?
I think I'll try this.
carlosfm said:Jojo, why don't you read this thread from the beginning?
You are making questions that have been answered here.
This thread is only 2 pages, read it.
Carlos,
I was reading it since the beginning of the thread. I was just confirming it though. So sorry if I disturbed you.
Thank you,
JojoD
Mad_K said:OPA549 should not be used with gain higher than 10x in audio applications
Not absolutely. It works fine at 19 when combined with a tone circuit preamp. I did what I found from here http://yooree.narod.ru/tale_3.chm - nice staff. Unfortunately eveything is in Russian.
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