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Headphone Systems Everything to do with Headphones

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Old 17th April 2017, 10:14 AM   #11
EUVL is offline EUVL  Europe
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The initial impression from the independent audition was that, even with ZGF,
"control of the entire spectrum is remarkable, and most evident in the bass region"
which corresponds with my own impressions.

That makes me curious how it might perform as a "power" amp driving 8-ohm speakers.
Like e.g. a HiVi B3N.
Mini DCAAV with Dayton ND91 ?

Well, actually much better than I thought, using all the NFB I can get, but still with a bias < 200mA.
So more fun options to try out.




Patrick

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File Type: asc UTHAiM Pwr Amp THD.asc (6.4 KB, 30 views)
File Type: asc UTHAiM Pwr Amp Freq.asc (6.4 KB, 17 views)
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Old 1st May 2017, 06:54 PM   #12
Stixx is offline Stixx  Germany
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I did in fact have the opportunity to audition the UTHAiM headphone amplifier as recently hatched
by Patrick. I am always all ears when there is a new concept of a headphone amplifier to try out,
so I "quickly" built a pair of them on the boards I got from Patrick, and he also borrowed me a
version he built sporting global feedback.

Both were quickly rigged up on a breadboard and powered by a pair of the cap multiplier psu's I
initially used for the F5 HA, with a quick change to output the suggested +/- 24V.

My first impression was that both versions sound almost like power amps... with power in abundance,
a full tonality and with very good control over the entire spectrum. When you like deep and hard bass,
look no further. Mids and Highs do sound like a good ZGF amplifier... natural with a total absence
of harshness or other artifacts that I remember from my first forays into solid state territory
(long before I built the DAO or F5 HA).

Switching over to the version with feedback (using the same psu) I initially was surprised that it sounded
quite the same, but concentrated listening to well known tracks revealed that there are differences.
To my ears, and in my subjective perception, everything sounds a bit harder, the tonality of instruments
gets shifted slightly, and bass precision is now bordering brutality.

I, personally, prefer listening to the UTAiM with zero global feedback as it is more natural sounding.
You pick your poison.
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Old 1st May 2017, 07:01 PM   #13
EUVL is offline EUVL  Europe
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Thanks for the independent audition.
As said in the title, this is about having fun, trying out configurations, and hearing how they differ.


Patrick
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Old 1st May 2017, 07:53 PM   #14
EUVL is offline EUVL  Europe
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Oh, perhaps you care to tell us what phone(s)you were using for the listening tests ?


Patrick
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Old 2nd May 2017, 05:10 AM   #15
EUVL is offline EUVL  Europe
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BTW, if you have a high impedance phone (>100R), or you want less output control, consider to replace :

Q11 with 2SK216 (pin compatible, just need to bend the legs)
Q12 with 2SJ79 (pin compatible, just need to bend the legs)
R31 with 2R

R21, 22 would have to be adjusted accordingly.
Nominally they should have about 1.2~1,4V across them, depending on the Vgs of Q11, 12.
When biased to 70mA, the output impedance without feedback is about 5 ohm.
Distortion will decrease significantly, due to lower capacitances of the output FETs.
You can always add 30dB or so NFB if you must have low Zout.




Patrick
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Old 2nd May 2017, 09:11 AM   #16
Stixx is offline Stixx  Germany
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Quote:
Oh, perhaps you care to tell us what phone(s)you were using for the listening tests ?
Sorry, I forgot to mention this.

Music was coming from the Pono Player and listening was done with either Sennheiser HD800 or Hifiman HE-500.
Those two do sound quite different although their frequency response resembles each other quite a bit,
with the Sennheiser sounding more analytical (but not troublesome with ZGF amps ) and the Hifiman sounding
warmer and more relaxed.

For me it's more a question of the personal mood which one I pick for listening... although I was under the impression
that the UTHAiM liked the low impedance Hifiman a little bit more ( it can deliver all the required current, and then some...).
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Old 2nd May 2017, 11:16 AM   #17
EUVL is offline EUVL  Europe
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Yes, as already mentioned :

low voltage high current load -- use 2SK1058 / 2SJ162 /0R3 / 150mA
high voltage low current load -- use 2SK216 / 2SJ79 /2R0 / 70mA


Patrick
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Old 3rd May 2017, 07:49 AM   #18
Nikon1975 is offline Nikon1975  Austria
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It's out:

GB for UTHAM Boards for Planet10

D.
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Old 3rd May 2017, 12:53 PM   #19
EUVL is offline EUVL  Europe
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Please support a fellow DIYer in need.
And thanks to D. for taking all the donkey work for the GB.


Thank you all,
Patrick
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Old 5th May 2017, 01:11 PM   #20
Morde is offline Morde  Finland
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Now that I have signed up for the GB, I would like to know what would be the preferred power supply for the UTHAiM? Stixx had used a +-24V cap multiplier, I suppose that could be a good starting point. Is there boards/schematics available for suitable cap multipliers?

Last edited by Morde; 5th May 2017 at 01:11 PM. Reason: typo
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