What is a Meta42 anyway?
Jun 6, 2002 at 6:35 AM Thread Starter Post #1 of 28

penaloza

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I take it's a variant of the CMOY or CHA47, but how is it different, does it have a crossfeed feature. Speaking of CMOY CHA47 or Meta42, which is better? Thanks, I was looking over some of the projects and tangent's site and it got my head spinning.
 
Jun 6, 2002 at 6:48 AM Post #2 of 28

eric343

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The META42 is an amp originally designed by Apheared (a long-lost guru of amps) for the Sennheiser HD600s. The design was reverse-engineered from Apheared's description by myself, Tangent, and Possum. From this, Tangent and I produced the rev. i2 (AKA ETA42) board, which was the first board to be ordered. I've built two amps on it, and they sound fantastic. Morsel and Tangent have since expanded and improved upon the design until the board can now be used to build an uber-amp complete with AD8610s in ClassA mode... the META42 board has been ordered by Tangent, and once he has recived and tested the boards, he will post a notice and web page regarding them. Tangent will sell the boards and ultra-hard-to-find buffers either separately or as a set, for an unknown sum.

The META42 does not by default have a crossfeed, however it can be added in as an external expansion board.

IMHO, the META42 whoops the Hansen board's butt. From here to Chicago
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Jun 6, 2002 at 10:39 AM Post #3 of 28

tangent

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The META42 has many antecedents:

- The Apheared #42
- The Jung multiloop design
- ppl's pocket amp, for the cascode design

It takes elements from all of these designs, and mushes them all together into a unique agglomeration. Sonically it's probably closest to the CHA47, but it's a much better design than that. (The CHA47 is cute, but it's a hack, really.)

You can add crossfeed to a META42, but then, you can add crossfeed to any amp. Contrast amps like the Hansen and the Corda HA-1, where crossfeed is an integral part of their design. For a while during the prototype phase, the META42 was set up to allow integral crossfeed, but it turned out that it was incompatible with one of our other design goals, so we ditched integral crossfeed. Now you simply add crossfeed as a filter on the input, like Chu Moy did with his own pocket amp, and the modified Linkwitz crossfeed. The modified Linkwitz pairs nicely with the META42, in fact.
 
Jun 6, 2002 at 5:20 PM Post #4 of 28

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Quote:

(The CHA47 is cute, but it's a hack, really.)


Hmmm . . . I am considering purchasing (in several months) a META42 so that I can do a comparison with the CHA-47. Right now, I absolutely am in love with the CHA-47 Penguin that JMT built for me, and I really am eager to see how it compares to such amps as the META42. It would surely make sense if the META42 sounded better than the CHA-47, considering it costs $170, and CHA-47 being less expensive . . . nevertheless, I'd still really like to compare them. And I assure you Tangent, as I'm sure others would too, the CHA-47 is not a hack, or were you joking? Damn hard to tell on these forums!
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Jun 6, 2002 at 6:57 PM Post #5 of 28

morsel

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The CHA47 uses two opamps in pseudo-parallel per channel, thus increasing the output current and lowering the output impedance, resulting in more control over the driver than a basic Cmoy. One of the two opamps amplifies both voltage and current and drives both the load and the second opamp which is configured as a unity gain current buffer. Is it a hack? That is a matter of semantics and rhetoric. Regardless, the META42 blows it away, and this is why:

The META42 is a two stage amplifier. A voltage gain opamp drives an Elantec unity gain current buffer, which is vastly superior to an opamp as an output device. The input stage only amplifies voltage, which it is good at doing. Since the input impedance of the output stage is high, the opamp does not have to strain to drive the output stage. The output stage only amplifies current, which it is good at doing.

Global or multiloop feedback assures that distortion caused by the current buffer heating up or having a hard time with the load presented by the headphones is corrected. A FET cascode current source biases the opamp into class A operation for sweeter sound.

The META42 compares to commercial headphone amps priced above $1000 if built with high end components.
 
Jun 6, 2002 at 7:19 PM Post #6 of 28

Nezer

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Using quaality components any idea about how much building one of these buggers will run?
 
Jun 6, 2002 at 7:25 PM Post #7 of 28

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Morsel,

Great explanation; I am now a tad more informed about technical audio jargon, about which I know very little.

I can see now that a comparison between the CHA-47 and the META42 would be unnecessary and I would be comparing amps in totally different classess (poor, poor CHA-47. . I still love you, though).

Though I must say that I'm very interested in getting a META42 now, for it seems like a great amp! And if this is true about it competing with amps circa $1000 then it's a heck of a bargain too!

Tangent,

How much do you think it would cost for a totally decked-out META42? Does the buyer have options as to what he would like in it, as far as internal components are concerned?
 
Jun 6, 2002 at 8:22 PM Post #9 of 28

Nezer

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Hmm, just had an evil thought...

Maybe take two of these with single channel opamps and make a sort-of 'mini-blockhead' out of it?
 
Jun 6, 2002 at 8:27 PM Post #10 of 28

eric343

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Actually, there would be no need to use single opamps; the Maxes in the Blockhead are AFAIK regular stereo models with their outputs and inputs tied together.

And someday I do intend to try this... Does anyone know where to get the Neutrik combination XLR/quarter-inch jack? What's the pinout on the HD600 cable?

The amp would obviously need a switch for "regular" or "metablock" mode, because not all headphones are availible with the BlockHead cable...
 
Jun 6, 2002 at 8:35 PM Post #11 of 28

Nezer

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If I had the money I'd be tempted to ask you to build me one. Of course I would need a balanced source too...

I guess when you start getting to this level a $3500 amp doesnt seem that big of a deal when you're using a $5000 source.

Now, this 'metablock' (I love that name, BTW) would really rock with an integrated DAC ala AOS's cutie but modified to split the digital signal into two seperate DAC sections and outputing ina balanced configuration. Add a PCDP w/ Toslink and I do think you would have a pretty killer setup! Now, how much would *THAT* cost me?? :wink:
 
Jun 6, 2002 at 8:51 PM Post #12 of 28

eric343

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*Integrated* DAC?! Look, buddy, when you get into monoblocks and balanced sources, *external* DACs are the dish of the day
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I'm thinking a METABlock divided into two separate Hammond die-cast aluminum 1590TBK boxes with the $6 "Alps-Blue" stepped attenuators, on top of an Aos DAC in the double-width version of the same case. All the parts would run off an external power supply, Naim-style...
 
Jun 7, 2002 at 12:59 AM Post #13 of 28

tangent

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Regarding the CHA47 being a hack, morsel covered the "A47" part of it, but I was also referring to the fact that a CHA47 uses a Hansen board in a way it wasn't intended to be used. I've built a few CHA47s, and while it's preferrable to building A47s on protoboard, the CHA47 is still more difficult to build than a circuit board designed for that amp would be. I can build a META42 in about the same time as a CHA47, and the META42 has something like twice the number of parts.

I know this is gonna sound biased, but now that the META42 is here, I think the role for the CHA47 is greatly diminished. That isn't to say that the Hansen board is useless -- it's still great for its intended purpose, as a CMoy+crossfeed. And, a CHA47 is still smaller than a META42.

On the issue of price, it isn't very productive to talk about prices of DIY amps in the abstract -- I think I'm speaking for all the DBSE'ers here, not just myself. I can build a basic META42 that costs less than $100 that will sound and look good, and I can make a killer META42 that costs over $400 without straying from the path of reason. What does a META42 cost? The question's too broad to answer.
 
Jun 7, 2002 at 3:59 AM Post #14 of 28

Nezer

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Quote:

Originally posted by tangent
On the issue of price, it isn't very productive to talk about prices of DIY amps in the abstract -- I think I'm speaking for all the DBSE'ers here, not just myself. I can build a basic META42 that costs less than $100 that will sound and look good, and I can make a killer META42 that costs over $400 without straying from the path of reason. What does a META42 cost? The question's too broad to answer.


Yeah, I should know better...
 
Jun 7, 2002 at 6:28 PM Post #15 of 28

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Tangent,

This is a quote that you made in the "What's the next step up from JMT Cmoy's" thread in regards to the Elna Cerafines:

Quote:

If you want to put ELNA Cerafines in the META42 board, the only ones Erix offers that will fit are the 220uF/25V ones. Since the main power caps are doubled, you use two on a side, for 440uF. Not bad at all, IMHO, especially since Cerafines are supposed to be "fast".


You say they are 'fast,' though how do these Elna Cerafines
compare to other high-end caps that you might use on the board of a totally-all-out META42 (like the one offered on your 'make-a-quote' webpage, NOT the $400 super-crazy META42 you were talking about!) Do you know how much the Elna's cost (total) for the amount used on a typical META42 board?

Do you happen to know of any other exotic internal components that might be feasibly added to a META42?


(BTW, don't worry, I DO plan to buy a META42, I'm not just hammering you with questions for kicks!)
(Also, I decided to ask this question about Cerafines and exotic components publicly as opposed to w/ PM because I thought you could kill several birds with one stone if you answered these questions on a non-personal basis. Though if you'd like to PM me instead, that's fine too.)
 

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