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Review and Measurements of DarkVoice 336SE Headphone Amp

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amirm

amirm

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Thread Starter #43
Ah... Atma-Sphere's lamp boards...
Yeh, the designer (Ralph) is a good guy with nice knowledge of tube design. Paralleling that many tubes certainly lowers the output impedance but I just can't fathom keeping that many soldiers inline. :)
 

rebbiputzmaker

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#44

metal571

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#45
Hello and welcome @metal571 ,
Good to have you here. Would be glad to also see others big YT guys around (like DMS mentioning ASR in his Atom review). :)
Thanks I've been following this forum for some time but only recently signed up and started contributing to the Patreon. What Amir is doing is way too interesting for me to ignore, especially being an engineer myself.

PS I still really love the McIntosh aesthetic. Don't know why.
 

ripvw

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#46
PS I still really love the McIntosh aesthetic. Don't know why.
maybe 'cause they both look great and measure very well...

"As I said, it is difficult to believe from its measured performance that the McIntosh MC275 was designed almost half a century ago...Good audio engineering is timeless." —John Atkinson
 

Headphonaholic

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#47
I have been long awaiting this review! Thank you Amir and the person that sent in the Darkvoice. The results are more or less what I expected. Having owned one of these myself I will say it sounded good with high impedance headphones. I had only tried lower ones a few times and didn't like the results.

As for hum, I noticed the 6sn7 was always the cause but not every tube does it. I have a few NOS RCA and GE tubes that never had any audible hum. Meanwhile some newer production tubes had horrid hum.
 

solderdude

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#48
Hum could be caused by the heaters being fed AC (wires aren't twisted either) or could be picking up hum on the anode of input tube as it sticks out above the amp and is not screened.
In the latter case getting near the tube with your hand should change hum.
If that isn't the case it most likely is the AC on the heaters.
Also possible that it is the wiring layout but when changing tubes changes the hum this may not be the case.
 

SIY

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#52
Hum could be caused by the heaters being fed AC (wires aren't twisted either) or could be picking up hum on the anode of input tube as it sticks out above the amp and is not screened.
In the latter case getting near the tube with your hand should change hum.
If that isn't the case it most likely is the AC on the heaters.
Also possible that it is the wiring layout but when changing tubes changes the hum this may not be the case.
With good design, AC on the heaters won't cause a hum. If anyone knows what the heater power circuits look like, there may be an easy fix, which will also get rid of the sensitivity to tube choice. Generally, the heater power should be run balanced with the circuit floated up to a DC potential above the cathode, and everything referenced to ground at AC. Here is a 6SN7 preamp that uses AC on the heaters and is dead quiet irrespective of the 6SN7 chosen, and is configured the way I just described. R11, R112, and C109 do the DC biasing and AC ground reference. And note the way the heater winding is configured.

The very worst way to run heaters is to not have the heater supply tightly ground referenced. The second worst way is to reference one side of the heater supply to ground. In either of these cases, heater-to-cathode leakage can cause a hum problem. And this is a VERY common design error, especially from cut and paste "designers."

If the heater winding does not have a center tap, you can create one by connecting two 100 ohm resistors in series across the winding, then using the junction of the two resistors as the artificial center tap.
 
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#53
I just joined after stumbling on this review (too).
I had the 1st version of DV (not SE) and with DT990 600Ohm it was match made in heaven. No audible distortion, no elevated highs (pretty common on 990), no hum at all.

I don't have it anymore since I moved on to Oppo PM3s as my main headphones (30ohm).
Also 1st version didn't have any hum and were dead silent with most of the front tubes I had. I hear so many SE versions have hum, it must be something in 2nd version that changed.
 

KR8NUX

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#54
Hello and welcome @metal571 ,
Good to have you here. Would be glad to also see others big YT guys around (like DMS mentioning ASR in his Atom review). :)
Uh, I don't know, I kinda liked Marks(DMS) and then he took a biodynamic, ran his "burn-in" test and claimed burn in is real. I lost it then.
 
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#55
the only tube headphone amplifier that I would have any interest in:

https://quicksilveraudio.com/products/headphone-amplifier/

notice the output impedance at 2.2 ohms...

Mike Sanders has been making tube products at Quicksilver since 1981. He is a measurement guy and his products have always tested well with JA at Stereophile. In addition, all his designs use point-to-point wiring and Quicksilver designs have become legendary for their reliability and longevity. At $995 I can't afford it but perhaps one of our other members will find it interesting.
I

I have Mike Sanders Quicksilver Headphone amp for the last two weeks "Wow " !! it blows away my other two SS amps( both good quality name brand amps :p) in SQ quality I use it with my Audeze LCD-X and the Audeze ISine 20 IEM , it does have a slight hum once you cross 2 Oclock But I can live with it) once you start playing music it is not audible , I called mike ( he lives 30 mins away from me ) he has asked me to bring it in so he could check it out I have had the privilege of listening Chord Dave with a Woo Audio WA6-SE & WES 2I at CAF 2018 , I believe this amp is right up their in SQ to my subjective ears today I took out my PS audioDriectstream DAC from my main system and paired it with QS HP, listening to Quboz & Tidal via a macmini , the music seems to be Bi aural -coming from "outside of the Headphones " instead of middle of my head ! for me this is a must have item
 

solderdude

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#56
the music seems to be Bi aural -coming from "outside of the Headphones " instead of middle of my head ! for me this is a must have item
Are you sure the headphone amp is not wired in with L and R in counterphase ?
Voices should be smack in the middle between the ears, not outside of the head.
 
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SIY

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#57
Isn’t coached sighted listening a wonderful thing?:cool:
 

Dogen

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#59
As suggested earlier, I took out the power tube and let a badly humming NOS RCA 6sn7 burn in for a couple of days. Dang if it didn’t stop humming entirely! It puzzles me what makes the Darkvoice so sensitive to unused tubes, but this harebrained scheme actually worked.
 

Headphonaholic

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#60
As suggested earlier, I took out the power tube and let a badly humming NOS RCA 6sn7 burn in for a couple of days. Dang if it didn’t stop humming entirely! It puzzles me what makes the Darkvoice so sensitive to unused tubes, but this harebrained scheme actually worked.
Yeah I should warned you that won't always work. It worked with the stock tube, well like 30 minutes of burn in, but I've put many hours in on the new production tubes that hum very badly and it made zero difference.
 
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