[poorimpulsectrl]

I've searched through threads and have come up with this initial configuration but am looking for advice/input/criticism as to whether it will do what I want it to.

My headphones are Beyerdynamic DT770's, whose acoustic properties I love and reflect what I like to hear. I love my KSC-35's as well. No quibbles about either of these cans, they present music the way I like to hear it. My source is my soundcard, a Turtlebeach Santa Cruz, because the majority of music I listen to is on my computer.

I listen primarily to electronic music (bass rich, complex composition, spatial effects / positioning, soundstaging) so I want the amp to work well with the attributes of the music I listen to. I like detail but I can't stand brightness - for example Grado SR80's are painful for me to listen to. Bass and balance are equally important to me. I prefer a fun presentation over clinical.

Here's the configuration I came up with. If anything is missing or any one has any suggestions please do offer them.

OpAmp : AD8620
Power : Line Regulated 24V Wall wart
Input : Minijack, RCA Jacks
Output : 1/4" nickel
Crossfeed : No
Volume : Alps Blue
Resistors : Vishay
Class : A

 

[andrzejpw]

Have you given thought to the capacitors at all, choosing values, etc? The Elna Cerafine series has garnered a lot of praise. . .

 

[poorimpulsectrl]

I've read that stacked output buffers are important, but aren't they more important if you're running off batteries and not if the amp is stationary? I'm not sure what I should be considering when it comes to capacitors but I will opt to just throw money at the problem and get the Cerafines that people like.

So far I've been paying attention most to op-amp related threads. It sounds as though the AD8620 puts out a sound that I would like, that it's detailed, has good bass but not overly bright. I know the AD843 is considered better sounding when power isn't an issue (as it will not be an issue for my amp that will be plugged into a wall 24-7).

I also know that crossfeed is used on most max-out meta configurations but at the same time I kinda like having sounds isolated to a particular channel rather than being consolidated into one mass as crossfeed seems to imply. I'm not sure if that's what it actually does but that's the impression I got from the descriptions I've read so far.

 

[jasong]

Stationary Meta42's often have stacked buffers because the extra buffers draw more quiescent current from your battery in a portable Meta42, draining it faster. That's not an issue with wall wart power...and the added buffers do improve the sound.

All crossfeed implementations I have seen include a way to both modify the crossfeed effect and to defeat it altogether. So if you don't like the X-feed on a particular song, turn it off...

--Jasong

 

[dchan88]

I just built a META42 also. This is what I found:

1) Stack the output buffer 4 high does result in better musical flow. There are more contrast between musical notes.

2) The power supply filter can make a big difference. At the begining I used Black Gate 220 uf, but I found it did not sound better than my Panasonic portable CD amplifier, except it can play much louder. Then I switched to some generic and cheap capacitors of 2200 uf (4 of them), every area of sound reproduction improve dramatically.


Other parts of my META42:
- AD 8620
- Blue velvet pot

Have fun.

 

[poorimpulsectrl]

Okay, here's what I'm looking at now :

AD843 opamp
double stacked EL2001 buffers
Line Regulated 24V Wall wart
Alps Blue potentiometer
Wima power caps
Elna Cerafine PS Caps
Vishay resistors
biased to class A

any comments? criticism? suggestions?

thanks for the input thus far

 

[andrzejpw]

Hmm, AD843? I'd go with the 8620. Although I personally haven't heard the 843, a few here seem to like the 8620 over the 843.

 

[poorimpulsectrl]

Some people seem to think the difference between the two are negligible, others (notably Tangent, PPL) think the AD843 is better. The AD843 already rated as class-A, and the lesser power draw of the AD8620 isn't really a deciding factor since I'm running off the wall wart and not batteries. Tangent's description of the AD843 being more 'liquid' than the AD8620 has me intrigued.

It's not as if the AD8620 is a bad chip, it just seems as though for minimal added cost I can use the AD843, get potentially smoother sound and an op-amp that seems to fit better into the application of the amp. PPL seems to really think that if battery power isn't a limitation then the AD843 is the way to go.

Talking to people who have a meta42 with the Beyer DT770's, there are some who have the AD8620 and others who have the AD843 and both of them seem quite satisfied with the sound. So I guess it's somewhat of a toss up.