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Old 13th December 2011, 02:14 PM   #21
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Actualy ive already bought most part of szekerez. Ill build then so... im tring to test in proteus just to make my layout
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Old 23rd December 2011, 04:42 AM   #22
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i've build Szekerez at my protoboard. It's running ok. But i dont like too much the sound. I don't know but even with my HD515 or TripleFi 10 it's not so nice.
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Old 23rd December 2011, 07:22 AM   #23
GLooP is online now GLooP  Bulgaria
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Because you don't have a preamp Place a op-amp before the Mosfet.
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Old 23rd December 2011, 01:16 PM   #24
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Something like Chu-Moy? I Build that, and i conect Chu Moy Out and Szekerez In , something like that?

Or i make this combination -> HeadWize - Project Addendum: A Class A MOSFET Headphone Driver by Greg J. Szekeres ??

And what execcly i need this "preamp" to get better sound?

Sorry for basic questions but now im excite with this stuff
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Old 2nd January 2012, 09:27 PM   #25
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No one?

Ill try to build this version

Click the image to open in full size.
Would be ok with that ?

My only problem is this OPA132. I Dont find here it... if this amp is ok, what OPA should i use in opa132 place?
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File Type: gif szeke3.gif (4.5 KB, 82 views)
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Old 3rd January 2012, 12:03 AM   #26
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Just my personal opinion:

If it's supposed to be a practical yet still compatively simple headphone amp, I'd say the minimum would be an opamp with a push-pull class-A (richly biased class-AB) output stage, run from a split supply. Avoid AC-coupled outputs if possible. Headwize has a few such projects. For example, the SDS Labs amp should work well. (I'd use a 10k volume pot though, and a NE5532 should do fine for an opamp.) The Eaton amp is another contender, but would require reducing gain and output resistance considerably. (Here in Germany a modified Eaton on perfboard actually is quite popular, but a design problem resulting in a severely underbiased Darlington output stage means performance isn't all that hot.)

Triple.fi 10s are not easy to drive well. While they are very sensitive as you'd expect BA types to be, their impedance is a rollercoaster ride with a minimum of about 7 and a maximum of 65 ohms, mandating an output impedance of 1 ohm maximum. Achieving that without running into stability problems is not easy. (If you don't feel like shelling out for an RSA Hornet or SR-71, don't happen to have an iPhone 4 at hand and even RocketScientist's O2 amp still is too rich for your tastes, your best bet for driving them adequately without breaking the bank probably is a Sandisk Sansa Clip+ / Zip.)

As you progress to more complex concepts, you'll also learn about the uses of neat compact layouts and good grounding procedures.

Last edited by sgrossklass; 3rd January 2012 at 12:13 AM.
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Old 3rd January 2012, 01:19 AM   #27
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Oops... forgot that FiiO's E7 and even the little E6 should also do a pretty good job driving them Triple.fis. (But of course those are "black box" amps in all surface mount.) They'll have some audible noise, like the Clips do, but it's not too bad. The O2 really is the minimum when it comes to accomodating a truly wide range of headphones.

All of those obviously are a loooong way from a basic Szekeres amp in both circuitry and construction techniques. I wouldn't say building a good amp on protoboard is entirely impossible, but it sure is tough at the very least! Debugging a more complex concept also tends to require a scope or at least making an RF probe (so you can find oscillation).

You will need to decide whether you want to construct something from scratch or whether you want good performance. Getting both does not seem feasible at this point.
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Old 5th January 2012, 05:03 PM   #28
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I forgot about one neat little amplifier concept, the Apheared-47. That's fairly useful already, too, especially as a portable amp. When using a split +/-9V supply, any opamp that's halfway beefy in terms of output current should work quite well in one (4556s, 4580s or 5532s). For supplies of much less than +/-4.5 V, rail-rail parts seem advisable.

With only one more opamp over a classic Cmoy, this one should be quite DIY-friendly.
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Old 5th January 2012, 06:24 PM   #29
GLooP is online now GLooP  Bulgaria
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We actually did forget that, LOL

Here are my schematic and perfboard version for Apheared-47 (A47), tested and sounds quite nice for what it is. Mine tested to run good with NE5532, TL072, JRC4580. OPA2134 was not so fun, but my PSU was poor indeed. Can be used as preamp as well.
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File Type: png A47.png (17.4 KB, 67 views)
File Type: png A47-brd.png (24.8 KB, 63 views)

Last edited by GLooP; 5th January 2012 at 06:26 PM.
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Old 5th January 2012, 08:03 PM   #30
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Hmm, that layout has a big fat ground loop in it, going all the way around the board. Have you ever tried cutting the trace at, say, the bottom right corner? Actually I'd cut it there and in between the volume pot and output jack, and then run a wire from the now-disconnected piece directly to power ground.
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