Eric343, JMT and I all build META42s for others. Perhaps others will, too. (JMT hasn't got a customer I know of yet, but I do know how many boards he ordered. )

Would using dual EL2001 per channel in parallel improve the sound any?

(I could not post yesterday.)

Tangent has already covered the details, but I want to clarify that Audio&Me does not have a META42, but rather an amp based upon a distant ancestor board, thus people looking to this thread for a META42 review should be aware that they are barking up the wrong tree. This is not to say there is anything wrong with the other amp.

Kelly, you want to know more about good META42 configurations. We just started a thread on HeadWize to discuss this topic, but not enough people have gotten their boards and assembled and experimented with them yet. It is clearly something that will improve with age as configuration tuning occurs. There are several threads in the DIY section on HeadWize which cover various aspects of its development over the last few months, including the FET cascode current source, multiloop feedback, choosing opamps and buffers, etc.

I stand by my assertion that a good META42 configuration compares to multikilobuck amps, but the proof is in the pudding. Reviews of real META42 amps will appear soon enough.

http://tangentsoft.net/audio/meta42/

Morsel,
I realize there are several configurations of the META42. What I meant to ask was--when you say the META42 is comparable to expensive commercial amps, which configuation are *you* referring to?

Stacking buffers can improve the sound. I suggest you read Tangent's META42 pages. They are extensive. If you have further questions, there are threads in the DIY forum here and on HeadWize that talk about this sort of thing.

http://tangentsoft.net/audio/meta42/

Tangent also has a bunch of audio pages related to headphone amp building, including tutorials, choosing opamps, ordering parts, and ordering amps built by him.

http://tangentsoft.net/audio/
http://tangentsoft.net/audio/amp-quote/

Morsel,
I've spent some time at Tangent's site and HeadWize.

I'm asking you as explicitly as I know how to ask--which configuration of the META42 are you referring to when you state that it is comparable to expensive commercial amplifiers.

Also, if you'd like to qualify--to which commercial amplifiers have you compared this configuration of the META42 and in what ways would you say that it sounds better?

Claims like "The amp I helped design sounds as good as a megakilobuck amp" are too easily made from conjecture and hyperbole. While I'm certainly in no position to criticize that which I've not yet heard, it's difficult to take such a vague comparison seriously. If you've actually compared your META42 to other amps, tell us the details of both the META42 you're comparing and the amplifiers you're comparing to.

Is there room in the board for a regulator chip? And it HAS to be able to use AD8610 opamps and Elna Cerafine capacitors, I will not accept anything else. Otherwize I'm quite interested.

Hi Kelly,

This belongs in DIY, but here goes. As I mentioned before, we are still working out optimal resistor values, but for the purposes of answering your question I will assume a "reasonable" set of values that are not far out in left field.

The resistors should be of good quality and be hand matched for accuracy. The pot should be an Alps Blue, stepped attenuator, or other high quality device. The pot case should be grounded if necessary to reduce noise. Input capacitors C1 should be large high quality polypropylene film/foil or metalized film. The -3db of the input should be between 1Hz and .1Hz to minimize phase distortion and attenuation of low bass signals. This is determined by the values of C1 and R2. Power supply capacitors C2 and C3 should be as big and high quality as space allows, which can be an issue in small portable cases. 2000µF per rail should be doable. Reservoir caps C4 should be large fast films such as the Wima 10µF polyethylene. 12 AAA or dual 9V batteries are better than a single 9V, again space is a consideration. The opamp should be either the AD8610/20 (on a BrownDog adapter), which is generally considered to be the best, or perhaps one of the other high end opamps, although I can't think of any I would rather use. The FET cascode current source should be implemented using Fairchild FETs, they seem to behave better than some of the other brands. 1mA should be sufficient for the AD8610/20. Full multiloop feedback mode should be used instead of local or global feedback only. The buffers should be stacked. Depending on your headphone impedance and your ears, triple or even quadruple stacking may offer improvement over double stacking. Only a couple of people have tested this level of stacking, so it is premature to make strong statements about it. Anyway, that is an example of a high end configuration.

Morsel
Thank you, that was the first half. I'll be sure the META42 I audition meets those specs before judging it.

Now, to which expensive commercial amplifiers have you compared this to and what characteristics did you feel were better with this META42?

Sorry, I am writing as fast as I can, and two of you are talking.

Kelly, the response that talked about stacking and looking at Tangent's site was to Audio&Me. The response that starts "Hi Kelly" was written before your note I am responding to now.

I did not say, "The amp I helped design sounds as good as a megakilobuck amp". Please don't put your words into my mouth. My statement is based upon the statements of knowledgeable, respected, reputable people in the DIY community who have compared the technology used in the META42 to other high end amps. Comparing amps is a personal thing. People have differing opinions. The implication here is that the META42 is worthy of comparison to multikilobuck amps, based upon its technology. You can read these statements for yourself in the DIY sections of HeadFi and HeadWize, although you will have to be dilligent, as the information is scattered far and wide.

As a codesigner, I leave the kind of comparisons you are looking for to others, because anything I say could be interpreted as a conflict of interest, despite the fact that META42 was a totally non profit labor of love for me.

Audio&Me, take it to DIY please.

Morsel, Eric and Tangent (+ anyone else), please go to http://www.head-fi.org/forums/showth...threadid=13190 inquiring about an all out META42.

Anyone attack the CD3K in this thread yet? I'm ready for ya...

markl

I thought that the CD3000 was the worst sounding headphone at the tour.

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LOL. Yeah, odd as it is, attacks against the CD3K do seem to be popping up all over the place as people begin to hear them . . . Good Glaven, there's one now:

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I'll get you warmed up.

/clears throat

I haven't gone to any tour stops, yet I KNOW the CD3K didn't deserve to be in the same room as the high-end rack!