[Earwax]

I built my pimeta about a month ago and I've been tweaking the opamps and buffers since then, but I'm still not 100% satisfied with the amp's performance. It's nice and detailed, but just a bit too polite sounding. I wonder if there are capacitor tweaks that would make it sound a bit more dynamic. This is what I've got now:

C4 = 2.2μf metal polyester, the largest film cap with that lead spacing I could find at digikey

C2/C3 - 4 x 680μf Panasonic FMs

C1 = BC .27μf MKP metal polypro

AD843 + 2x BUF634 L/R, AD8610 + 1x BUF634 Ground
R11 is 110ohm
biased to class A with jfets purchased from Tangent.
(I've also tried ad825, 8620, and 8066)

Ideas?

 

[llmobll]

If you're looking for a different sound then the op-amps are your biggest tweak. Since you seemed to have rolled alot already, maybe its time for an upgrade? Though I agree tweaking the caps should help you find some change in sound, the pimeta has limits. What about 2 OPA637's on an adapter? Those can be had for cheap.

 

[Earwax]

Quote:

Originally Posted by llmobll the pimeta has limits

That's what I keep reading (in the amp section, not here).

I just have this gut feeling that something's holding this amp back compared to what I hear from my tweaked out cmoys.

 

[Megaptera]

How much do you need the input caps? If your source has a low DC offset you could try it without those. Might make a touch of difference.

And I'll second the possibility that you may want to go to a better amp. I really like the Pimeta, and it's twice as much as any rational person would ever need, but hey, why be rational unless you have to?

 

[bg4533]

Quote:

Originally Posted by Earwax That's what I keep reading (in the amp section, not here). I just have this gut feeling that something's holding this amp back compared to what I hear from my tweaked out cmoys.

I just finished up my Pimeta yesterday. It is about as maxed out as a Pimeta can be with Alps blue, Cerafines, OPA637/627, 4 buffers l/r, 2 buffers g, Elpac WM080, etc and I find it a bit disappointing. The sound is improved (and different) over Cmoys and a Mint I have built, but not quite as much as I thought it would have been. Things are a bit too smooth and less dynamic than I wanted. Detail is improved, but not quite as much as I expected. Maybe it still needs a bit of time to break in or something. I have a pair of Alessandro MS2s that should be here in a few days, I will start tweaking the Pimeta when I get them. My conclusion right now is that this Pimeta is not really all that much better than a nice Cmoy.

How are you powering your Pimeta Earwax?

 

[Earwax]

Do you have input caps on yours, bg? Removing those (as Megaptera suggests) is the first thing I'm going to try. I don't need them now, I'll just have to trust myself to remember to check DC voltages before moving the amp to any other system.

I've tried various power supplies, including an Elpac 24V. Right now it has a home-made linear regulator with a old AC wall wart. None of the power supplies has made much difference so far.

 

[bg4533]

I do not have input caps on my Pimeta. The output from the Pimeta only measures a DC offset of ~.5mV.

What source are you using with your Pimeta? What are your opinions of your source?

I am currently using an EMU 1212M which a lot of people really like. I find the sound to be a bit thin and lacking in dynamics. However, without the amp, the sound is a bit more dynamic. I am wondering if the Pimeta just requires good synergy with the source to sound decent. When I get a chance I will try the Pimeta with my Ipod mini and my Chaintech AV710 to see if I like the sound any more.

 

[setmenu]

The best mod I can think of for the Pimeta is to ditch the Buf 634's and
replace them with Intersil HA 5002's

Adapters will need to be made as the 5002 is not pin compatible with the
634.
Making the adapters is quite fiddly work, but well worth the effort...


Setmenu

 

[flecom]

my setup currently is...

Sonica (optical) > Behringer UltraCurve > PIMETA 2xOPA637BP 1xOPA627AP 2x BUF634's for L&R 1x for GND > AKG K1000's and it sounds quite nice

ive played around with different things (power caps etc) and by far the most difference you will hear component wise is the opamp, different opamps just have different sounds... i really love the 637's they are very clear and detailed, but not sharp or harsh... arnt the fastest OPAMPs tho

also no input caps, input caps = devil... unless your source has DC-offset of course... then they are can savers hehe

 

[Earwax]

Input caps be gone!

That's made an clear improvement in low end clarity at least.

I also wonder if the TLE is a bottleneck, with it's 20ma current capability?

 

[Earwax]

Bye bye, TLE!

 

[bg4533]

Quote:

Originally Posted by Earwax Bye bye, TLE!

Ummm....I don't think you can just remove the TLE unless you already have a dual voltage PSU and even then I don't think you can just remove it.

I just started listening to my Etymotic ER6s with the Pimeta. The difference between the Pimeta and my other amps is quite noticable here. For the most part the Pimeta distroys the other amps. A cmoy with a OPA2132 provides a bit more "sloppy bass" that I like with the ER6s, but the Pimeta is a clear cut winner everywhere else. I guess my Audio Technica ATH-A500s don't like the Pimeta too much. Oh well, I am selling them anyway. Hopefully my MS2s play well with the Pimeta.

 

[Earwax]

True, you can't just remove it. You need a resistor divider in it's place. Here's a thread that describes how to do it in the Meta42 http://www6.head-fi.org/forums/showt...=tle+resistors
Same idea with the Pimeta, the ground trace is the one with the letters "TLE" silkscreened on top of it.

luckily, I had a couple of the mini panasonic metal films still around.

Who said the pimeta has limits? It's singing now!

 

[sanaka]

I hope the more knowledgable will chime in here, but I think the ground channel buffer(s) 'override,' orincrease, or, uh, buffer, the 20mA limitation of the TLE. Otherwise it would be quite rediculous, wouldn't it?

Peace,
Sanaka

 

[NOTHINGness]

So if removing the TLE improved the sound, the next logical step would be to stack a few TLEs to see if that gives the same change.

Also has anyone tried diamond buffers on the Pimeta? For the price it seems more logical than stacking 4xbuf634s.