META42 questions
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kheldar

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Im planning on building a meta42 for my portable listening, but i have some questions:

I have BUF634 in the to32 (??) package, is there going to be much of a problem building a small board to mount 2 or 3 of them in place of the elantec buffers? will they work and give comparable results to the elantec? or should i just stick with the originals?

same question for the opamps, i have a pair of 627's, are they worth using in the meta? or should i save them for another project and go with the AD chips?

My headphones are grado sr125's, is there anything that i should look for/against when choosing components?

thanks
 
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morsel

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I would not use the BUF634. They do not have the same pinout as the EL2001/2, they don't sound as good, and the circuit was not designed for them. You can order Elantec buffers along with your board. They are inexpensive.

Your Grado SR125 headphones are only 32 Ohms impedance. You will benefit from stacking buffers. Use as much power supply capacitance as you can. Don't use those OPA627 opamps, use AD8610/20 on a BrownDog adapter instead.
 
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Nezer

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Quote:

Originally posted by morsel
IDon't use those OPA627 opamps, use AD8610/20 on a BrownDog adapter instead.


But the 627s are less filling!

(Now it's your turn to say the AD8610 tastes great)
 
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tangent

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Now morsel, I know you hate Burr Brown...but come on! One of your objections is the cost, but he's already got the chips!

So here's this guy trying to get out of spending $10 on a set of buffers, and you're trying to convince him that unless he spends $40 between Analog and Brown Dog that the amp will suck.
 
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Nezer

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Quote:

Originally posted by tangent
Now morsel, I know you hate Burr Brown...but come on! One of your objections is the cost, but he's already got the chips!

So here's this guy trying to get out of spending $10 on a set of buffers, and you're trying to convince him that unless he spends $40 between Analog and Brown Dog that the amp will suck.


ROTFL... Now children....
 
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kheldar

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laf... i dont mind... i actualy have a pair of 8310's, i just have to build an adapter for them.

oh, and find some industrial strength muscle relaxant to solder them... =) Its not so much the money i was trying to save on the opamps, just the soldering.

id like to roll some chips through the amp when its finished, but all the good ones seem to be in SMT format now, anyone know of a test clip for them? or am i stuck soldering?
 
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morsel

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They are very easy to solder. Pre-flux the pads with a flux pen if you wish. Use a heatsink to clamp the IC to the adapter. Center the IC over the pads by nudging it with the end of a paperclip. Solder one leg and recheck the positioning. Solder the rest of the legs. Swab with isopropyl alcohol to remove excess flux. Only takes a few minutes.
 
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kheldar

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OK, that sounds easy enough.

im sure it will be another story once i get down to putting it together...

hopefully, im ordering my board and buffers tonite, just waiting for a return emai from tangent... soon ill be a member of team meta42 =)
 
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geom_tol

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kheldar: I was really nervous about soldering the soic ad8620 onto the brown dog adapter.
But like Morsel wrote it is not that hard. I didn't even think of clamping the chip with a heatsink, I just lay the chip on the pads and started soldering. I did 4 of them in about 10 minutes.
You don't even need an ultra-small soldering tip, I used my regular tip (cone shaped thing with the tip cut off at an angle to create a small flat)
 
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puppyslugg

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I used a thin strip of duct tape to hold the ad8610 to the adaptor. I wrapped a 30ga wire around the tip of my iron. Worked great. (Both ideas were posted at head-fi/headwize.)
 
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