the right op amp?
Aug 3, 2008 at 2:14 PM Thread Starter Post #1 of 6

rds

Headphoneus Supremus
Joined
May 4, 2008
Posts
2,045
Likes
30
Rightness is not an absolute thing. It is a determination based on circumstances and acceptable compromises.
I'm building a cmoy style amp for my dad to use with Sennheiser hd555s. He is not an audiophile and he what he actually asked me for is a volume control
tongue.gif

His hearing is a little rolled off, so sibilance is a good thing. The 555s are not sibilant to say the least, but they were chosen for comfort (when wearing glasses).
So this all comes down to the fact that I'm looking for a bright opamp. I don't think it could be too bright, but it needs to be nice overall. So far I'm looking at the ad8620 as the best choice I know of.
Please bring on the suggestions (amp mods are welcome too).
icon10.gif


EDIT I'm using a 24V PS, and a LMH6321 to buffer the Vground
 
Aug 4, 2008 at 6:52 AM Post #2 of 6

amb

Member of the Trade: AMB Laboratories
Joined
Apr 1, 2004
Posts
4,933
Likes
41
Sonic differences between (good) opamps are, in absolute terms, subtle. While such differences means the world to us audiophiles, they are simply too minute for hear loss correction. What's needed is equalization, or at minimum choose headphones that have a hot high-end to make up for his hearing. Even the most "bright" sounding opamp isn't going to be enough to overcome the combination of rolled-off hearing + dark headphones.
 
Aug 4, 2008 at 12:35 PM Post #4 of 6

TzeYang

500+ Head-Fier
Joined
Mar 19, 2006
Posts
960
Likes
10
amb,

as a wannabe engineering student, I know how it's impossible to tell the difference based on what I know about science.

But srsly, there's a difference. I cant tell which "sounds" nicer but I know which one makes me fatigue. Can you explain why though? The opamps used are all very stable FET types.
 
Aug 4, 2008 at 12:48 PM Post #5 of 6

rds

Headphoneus Supremus
Joined
May 4, 2008
Posts
2,045
Likes
30
Here's a crazy idea:
What about a Chebyshev filter? It has a nice gain curve before the cutoff frequency. If I set the cutoff at 22kHz that might do the trick (?). What do you think?

Quote:

Can you explain why though?


there is no ideal opamp?
 
Aug 4, 2008 at 7:44 PM Post #6 of 6

amb

Member of the Trade: AMB Laboratories
Joined
Apr 1, 2004
Posts
4,933
Likes
41
Quote:

Originally Posted by rds /img/forum/go_quote.gif
Here's a crazy idea:
What about a Chebyshev filter? It has a nice gain curve before the cutoff frequency. If I set the cutoff at 22kHz that might do the trick (?). What do you think?



It might. If you know what his hearing loss curve is, then you could try to set the peakiness of the filter to match.
 

Users who are viewing this thread

Top