[SENOR4Q]

I am interested in "upgrading" my AD8620 opamp to either the OPA637 or AD843. TO those who have heard both, I'm interested in which did you prefer, why, and what headphones you were using. Also, is there a general rule of thumb as to which opamp will work best with a type of headphone? I'm sure this won't just help me out but anyone interested in getting or upgrading a META42.

 

[kajohndet]

Hi,

I started my META with AD843's. I found them to be too aggressive sounding. To my ears, I found them to be too harsch in mid-high region. Later I had my hand on OPA637's and they were the way to go for me. They sound more relaxing and neutral with dark background (again, to my ears). Bottom end and mid range are just about right without that harschness I had heard with 843's. I still own both and prefer 637's to 843's for most of the phones I've had (previously owned HD580 w/ Clou, CD3000, Ety4P/S, etc.)

hope this help a bit

 

[SENOR4Q]

Thanks alot, it does help. One question though, by "agressive sounding", do you mean too revealing or too much high end sizzle, making it too bright?

 

[kajohndet]

It's not the high end that mattered to me. It's the mid-high harschness. At the first time I heard, I thought they needed time to burn in. But as time went by It's still there and quite bothered me. I couldn't listen for long period as it made me headache. When I switched to OPA637, Ditto! way to go!

By the way, it could be that my ears are especially sensitive to around that frequency range or my specific taste of sound. So you should get more opinion from other fellow headfiers too. There're many people who're happy with their 843's.

 

[puppyslugg]

kajohndet:

How much were the ad843 biased class A?

 

[kajohndet]

Quote:

Originally posted by puppyslugg kajohndet: How much were the ad843 biased class A?

puppyslugg,

I don't understand the question? Is it about configuration?

 

[puppyslugg]

Hi kajohndet,

From my experience with the ad843, the amount class A biasing, made quite a difference in how it sounded. I initiallly used about 3ma of biasing, but it wasn't until I tried 5ma that the ad843 really came alive. Without any class A biasing, I thought the ad843 was just average.

 

[kajohndet]

Quote:

Originally posted by puppyslugg Hi kajohndet, From my experience with the ad843, the amount class A biasing, made quite a difference in how it sounded. I initiallly used about 3ma of biasing, but it wasn't until I tried 5ma that the ad843 really came alive. Without any class A biasing, I thought the ad843 was just average.

puppyslugg,

I'm not quite not sure about that since I'm not a technical guy at all. Configuration of my amp is the following

- AD843KN single op-amps (2)
- Vishay/Dale RN55D hand matched resistors
- Current source to bias to Class A
- Stacked output buffers
- Elna Cerafine 470µF/25v power supply capacitors
- WIMA 6.8µF/50v reservior capacitors
- Alps Blue Velvet 100K ohm potentiometer
- Cardas gold plated/teflon insulated RCA inputs
- Neutrik 1/4" locking headphone jack
- Dual 9v/wall wart jack
- Rocker on/off switch
- Blue LED

How do you think?

Thanks