PPA or Pimeta?
Jun 18, 2004 at 5:52 PM Thread Starter Post #1 of 15

Juergen

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I am considering building a headphone amp and have narrowed it down to either a Pimeta or a PPA. I will buy either board from Tangent's site along with some of the harder to find parts and most of the rest from DigiKey and/or Newark. The following are some points that I would be interested in hearing anyone's opinion on:

1. Cost - I realize that there is almost an infinite array of optional parts and configurations for both designs. For a start I will stick to the basic equipment (no crossfeed, diamond buffers, etc). I don't plan on buying any really high end components like Black Gates (most likely Panasonic FC caps, etc). I guess what I'm asking is what would it cost to build a PPA vs. a Pimeta?

2. Complexity - Neither design is as simple as say a CMOY. To me the PPA has more parts than a Pimeta but shouldn't be any harder to assemble (just more of the same). I would imagine that troubleshooting a PPA would be harder than for a Pimeta. It seems the most complex part of the whole thing is choosing and finding components.

3. Sound - I would like to tackle a PPA if items 1 and 2 are not a major issue. Currently I own a self modded MF XcanV2 amp. How would either of these designs compare to it? (OK here we go, talk about a subjective question
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Jun 18, 2004 at 7:06 PM Post #2 of 15

Megaptera

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A Pimeta would probably cost you about $75-125, and a PPA could easily run to twice that. Either way, I'd recommend you socket things like buffers and opamps, to make it easy to upgrade those later if you want to, and use class A biasing for a little more inexpensive goodness.

The PPA will be harder to troubleshoot, but the actual building of it is not considerably harder than the Pimeta -- I found it to be more of the same, just as you say.

I can't really help you with the comparison to your current amp, but I do wonder what kind of headphones you like. Both amps are really good for most cans, but certain combinations may make more sense regardless of cost (like if you've got HD650s, I'd go with the PPA, but SR60s, it wouldn't be as obvious an improvement).
 
Jun 20, 2004 at 3:29 AM Post #3 of 15

Juergen

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I did a quick total on the parts for a PPA with decent parts and it's $150+ (like you said) and rising but that's ok. I've seen them for more than $500. Of course that's fully assembled and likely maxed out. I think I will do this!
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Now I have to go into the details like figuring gain and such. Any suggestions on gain for my HD600s?
 
Jun 20, 2004 at 6:49 AM Post #5 of 15

CBMC

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depends on what opamps you will be using. If you are using the burr brown opa637's then I would suggest a gain of at least 10 or 11. Not that I am any kind of a opamp connoisseur but the burr brown opa637 is my favorite out of what I have tried. Which include the AD8610, AD8620 AD843(which I think is better than the AD8610 or 8620), and a few of the cheap no name ones.
 
Jun 20, 2004 at 7:20 AM Post #6 of 15

rayofsi

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with opa637/627 opamps and a gain of 6, anything past the 12 o clock position hurts my ears.

min of gain 5 is required for 637/627, and gain 6 = less stability issues
 
Jun 22, 2004 at 4:42 AM Post #7 of 15

Juergen

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Well I did it! I ordered the parts from Digikey & Newark (Panasonic FCs, Vishay Rs, OPA633 & 627s, Neutrik jack, ALPS pot, Hammond case, etc) around $170 w/o shipping, tax and psu. As I type this I realize I haven't ordered the most important part of all.......the PPA 1.1 board!!!!
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I'll fix that. As far as gain is concerned I got resistors that will give me a gain of 6, 8 or 11. That should do it. Thanks again for the help (also thanks in advance, I'm sure I'll be back with questions
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5 minutes later: My total is around $210 now...
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Jun 22, 2004 at 1:37 PM Post #8 of 15

Megaptera

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Quote:

5 minutes later: My total is around $210 now...


Be prepared -- it's really easy for this number to keep going up. You start thinking innocent little thoughts like "what if I added another input?" that turn into "what if I added five more inputs?" Nothing sounds sweeter than the amp you built yourself and could not afford
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Jun 22, 2004 at 1:46 PM Post #9 of 15

Dreamslacker

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Use Panasonic FC's. You don't need exotic/ boutique parts like Cerafine's or Blackgate's in the reservoir. Chances are, low impedance caps like Sanyo Oscon's or Panasonic FC's will outperform them contary to what others say.
I've replaced the opamp bypass caps from Blackgate's to Oscons' in a Rotel CDP to great results. Ditto with Silmic's to Oscon's in my Pioneer player.
You could leave 2 slower, ordinary caps in the reservoir to give the sound a little more air & roll-off.
 
Jun 22, 2004 at 2:03 PM Post #10 of 15

Voodoochile

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Yeah, that's what happens... another set of inputs... nicer jacks... different switches, or a nice rotary for switching them. Knobs and cases can get crazy, so-on. Buying teflon insulated wire gets pretty expensive, especially if you want to build one amp. Next thing you know, you are saying 'you know, it costs quite a bit more than the sum of the parts schedule to build one of these!'

Oh well, as you will soon find out, it was money well-spent. It's a really nice rig.
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Jun 22, 2004 at 4:47 PM Post #11 of 15

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Quote:

Originally Posted by Voodoochile
Oh well, as you will soon find out, it was money well-spent. It's a really nice rig.
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I need to find a way to convince my wife that our money is well spent on this stuff!
 
Jun 22, 2004 at 5:00 PM Post #12 of 15

Voodoochile

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Uh-oh... now you're putting the cart before the horse!
Don't start trying to justify anything or you may land yourself in some sort of support group.

There have actually been threads here on "should I tell my wife about the new amp", and "Do you think my wife will notice that my HD580s are now HD650s?" I'm not joking.
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Jun 22, 2004 at 6:01 PM Post #13 of 15

Juergen

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Quote:

Originally Posted by Megaptera
Be prepared -- it's really easy for this number to keep going up.


I did order a crossfeed board but I won't deal with that till the amp is working. Hmmm those diamond buffers sound intersting.....


Quote:

Originally Posted by Dreamslacker
Use Panasonic FC's. You don't need exotic/ boutique parts like....


Exactly. The most expensive 'optional' parts were the Burr Browns, the Alps pot and the Neutrik jack. I know I would never forgive myself if I didn't at least go with those parts. The Panasonics didn't cost much and are highly regarded, in fact I used them to replace the generic caps in my XCanV2.


Quote:

Originally Posted by drewd
I need to find a way to convince my wife that our money is well spent on this stuff!


What she doesn't know can't hurt her
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Jun 22, 2004 at 10:46 PM Post #14 of 15

Megaptera

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Quote:

I need to find a way to convince my wife that our money is well spent on this stuff!


Make small cheap amps for friends as birthday gifts, fix up broken electronics around the house, hack together a superbright LED flashlight -- you can display practicality and feed the monkey at the same time.
 
Jun 22, 2004 at 11:04 PM Post #15 of 15

drewd

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Quote:

Originally Posted by Juergen
What she doesn't know can't hurt her
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Heheh...she's a world-class noticer! I try to keep a step ahead of her by pointing out that the amps that sell on Ebay finance my habit. There's still that "What's yours is mine and what's mine is mine" attitude to adjust, though
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I'll prevail through sheer cussedness!

-Drew
 

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