how much does AD8620 profits from biasing into Class A?
Oct 8, 2003 at 6:44 PM Thread Starter Post #1 of 8
Glassman

Glassman

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the question is clear.. I've saw somewhere sometimes that it doesn't help a lot or even not at all.. I'm asking becouse I've just biased AD826s with 3mA each channel - I use them as a buffers after AD8620 as I/V and filter stage on my Revo soundcard and it does help them MUCH!

what are your expiriences from using AD8620 in METAs or PPAs biased vs. not biased?
 
Oct 8, 2003 at 7:04 PM Post #2 of 8
Glassman,
The difference after biasing the AD8620 isn't any huge. I have experienced much bigger improvement with OPA2132 or OPA627(637) instead.
 
Oct 8, 2003 at 7:07 PM Post #3 of 8
but are there any?
confused.gif
 
Oct 8, 2003 at 7:29 PM Post #4 of 8
I've not really thought about this. I've planned to bias all op-amps to class A. However, it is strange that there is a difference, because if the op-amp is driving a buffer (such as the BUF634) it has a minimum input impedance of 8M ohms. Usually, problems with crossover distortion occur trying to drive low impedances. Hmmm....



JF
 
Oct 8, 2003 at 10:17 PM Post #5 of 8
Quote:

Originally posted by JohnFerrier
...Usually, problems with crossover distortion occur trying to drive low impedances. Hmmm....
JF


Also at lower voltage levels and/or higher frequencies.
 
Oct 8, 2003 at 10:30 PM Post #6 of 8
well, tis hard to dispute with jeff, as he's clued up to the gums! However, listening is subjective, and Glassman, you said yourself it made a difference, so whats the point in asking? If you like it is all that matters!

g
 
Oct 8, 2003 at 10:56 PM Post #7 of 8
Quote:

Originally posted by jeffreyj
Also at lower voltage levels...


...good point.

Quote:

Originally posted by jeffreyj
...and/or higher frequencies.


...and another.


JF
 
Oct 9, 2003 at 4:20 AM Post #8 of 8
Quote:

Originally posted by guzzler
well, tis hard to dispute with jeff, as he's clued up to the gums! However, listening is subjective, and Glassman, you said yourself it made a difference, so whats the point in asking? If you like it is all that matters!

g


I was talking about AD826, not AD8620.. I wonder if AD8620 could also improve after biasing, but I've read somewhere that this one sounds the same biased or not biased.. I want to hear your expiriences..
 
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