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Help choosing project.

post #1 of 54
1/11/12 at 8:30am
Thread Starter 
I am new to audiophilia, but not electronics. I am currently running an asus Xonar STX --> Ultrasone Pro 750,but the nature of the Xonar adds to the sibilant nature of the highs and seems to further recess the mids on these phones. Not to mention the coldness of the sound.

I would like to build an amp that would be well suited to these phones, bringing out some warmth and taming the highs some.

I have not heard any dedicated hp amps before, so I don't know where to start. I figure the amp would need a low output impedance, because the impedance of the Ultrasones is low, but I don't know if I would be better off with a ss, tube, or hybrid.

Any help would be appreciated. Thanks in advance.
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post #2 of 54
1/11/12 at 9:24am

Its hard to beat AMB Labs CK2III with its changeable gain options...IMHO the CK2III is the best bang for the buck out there. This is just my personal opinion.

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post #3 of 54
1/11/12 at 9:31am

If you're looking for warmth, the AMB Mini3 is a very warm sounding portable amp which isn't very difficult to build. I'd recommend tubes as well for the warmth you are looking for, but your Ultrasones have a low impedance of 40ohms so you'll really need an amp coupled with output transformers. Output transformers add significantly to the cost over OTL designs. 

 

Some projects to look into:

 

Bottlehead S.E.X.

Bottlehead Smack (not the Crack, only suitable for high impedance cans)

Millett Jonokuchi

Beezar Torpedo

 

I hesitate to recommend the Torpedo as I haven't finished my build yet and haven't been able to listen to it with low impedance cans, but it's the lowest cost build of the bunch at under $300 and TomB and Dsavitsk have put an immense amount of effort into it. 

 

Also note that nearly all tube amps are high voltage, so the utmost care needs to be administered when building any of them. 

 


Edited by HiGHFLYiN9 - 1/11/12 at 9:35am
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post #4 of 54
1/11/12 at 10:25am
Thread Starter 
Quote:
Originally Posted by HiGHFLYiN9 View Post

If you're looking for warmth, the AMB Mini3 is a very warm sounding portable amp which isn't very difficult to build. I'd recommend tubes as well for the warmth you are looking for, but your Ultrasones have a low impedance of 40ohms so you'll really need an amp coupled with output transformers. Output transformers add significantly to the cost over OTL designs. 

 

Some projects to look into:

 

Bottlehead S.E.X.

Bottlehead Smack (not the Crack, only suitable for high impedance cans)

Millett Jonokuchi

Beezar Torpedo

 

I hesitate to recommend the Torpedo as I haven't finished my build yet and haven't been able to listen to it with low impedance cans, but it's the lowest cost build of the bunch at under $300 and TomB and Dsavitsk have put an immense amount of effort into it. 

 

Also note that nearly all tube amps are high voltage, so the utmost care needs to be administered when building any of them. 

 

Thanks for the recommendations!


I'm looking hard at the torpedo now.

 

Also, I know the dangers of higher voltage, as I work on this stuff everyday:

http://www.joy.com

 

All 480V and up on the power side of things.

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post #5 of 54
1/11/12 at 10:49pm

Maybe a AMB M3 since you are familiar with electronics

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post #6 of 54
1/12/12 at 5:33am
Thread Starter 
Quote:
Originally Posted by Starfire View Post

Maybe a AMB M3 since you are familiar with electronics


This was actually my first thought. I'm really wish I had somewhere near me that I could demo some different amps.
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post #7 of 54
1/12/12 at 12:18pm

The Xonar STX's headamp is based on the TI TPA6120 amplifier chip.

 

Most implementations follow the datasheet and have an output impedance of ~10R. You may be able to modify this by paralleling the output resistor with an inductor of 1~2 uH (per channel) to bring the output impedance down. This will improve the damping factor which can be significant with low impedance phones  The effect will probably still be marginal (hard to hear) though.

 

Other than that you are unlikely to get an improvement by moving to another SS amp. The TPA6120 is a very competent chip.

 

Give the equipment you have a chance, the sound should be very good, particularly where the electronics is concerned. Changing 'phones will have more impact than changing the amp.

 

w

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post #8 of 54
1/12/12 at 12:41pm

 

 

Quote:
Originally Posted by ExecuteMethod View Post


This was actually my first thought. I'm really wish I had somewhere near me that I could demo some different amps.


 

 

Where are you from?

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post #9 of 54
1/14/12 at 12:23pm

Driving toward low output impedance is not the best scenario for all low impedance headphones.  I can't speak for Ultrasones, but Grados don't like the very low impedance that comes with most solid state outputs, because it promotes the very thing you're trying to combat: high-end harshness.

 

Also, a number of good amps have been mentioned.  Keep in mind that there are qualities in SS amps that are very different than your sound card.  The CKKIII that vixr mentions, for instance, is a zero-feedback, fully discrete* solid-state design and will sound very much like a good tube amp.

 

 

* it uses an opamp for offset correction ...

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post #10 of 54
1/14/12 at 5:42pm

What's kind of neat about SS amps with op-amps is you can roll them like tubes.  I know I've changed a few in my M3 and there definitely an audible difference, though I think my M3 will be going up for sale since I built the Beta22

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post #11 of 54
1/14/12 at 7:03pm
Quote:
Originally Posted by tomb View Post

low impedance...   ...promotes...   ...high-end harshness.

 

How does it do that then?

 

w

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post #12 of 54
1/14/12 at 7:06pm

Overdamping maybe?

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post #13 of 54
1/14/12 at 7:29pm

Close, but no cigar.

 

w

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post #14 of 54
1/14/12 at 11:14pm



 

Quote:
Originally Posted by wakibaki View Post

 

How does it do that then?

 

w


The Dscope shows it.

 

Seriously, you probably won't accept this ... but one of the leading designers around here and on DIY Audio has done nothing but design and build amps for Grados for a lot longer than than I've even been on this forum.  He's tried it with many output impedances - and the drive to super-low output impedance and higher damping factors make Grados worse.  I think a Z of 15 is what he found as optimum.  I've certainly heard the difference enough times with his equipment and mine to accept it as fact.

 

Overdamping does cause it and perhaps this may explain why:

http://www.head-fi.org/t/570809/grado-ps500s-new-grados/480#post_7812935

 

 


Edited by tomb - 1/15/12 at 12:20am
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post #15 of 54
1/14/12 at 11:56pm
Quote:
Originally Posted by wakibaki View Post

Close, but no cigar.

 

w



Very constructive response rolleyes.gif

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