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Review and Measurements of HIFIMAN EF2A DAC and Headphone Amp

Jimster480

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Having different tubes could have introduced the problem no?
Or will the DAC itself still be overdriving the input? I was thinking that maybe its overdriving these specific tubes?
 

Valorum

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I read at one point that tubes were desirable due to how "nicely" they clipped. While this is obviously subjective, does this apply to this clipping scenario?
 

RayDunzl

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I read at one point that tubes were desirable due to how "nicely" they clipped. While this is obviously subjective, does this apply to this clipping scenario?

The traditional urban legend old wives tale view of tube clipping vs SS:

1528244175338.png

A transistor clips (mostly) because it runs out of rail volts. Increase the rail volts, everything else the same, and no more clip. Smoke, maybe.

A tube clips because... well, they seem to have lots of volts on the anode to attract those free floating electrons... maybe* there's just so many available electrons to be boiled off the cathode at a specific cathode temperature, but not a hard limit... or it is ultimately driven into cutoff on the other swing.

* reading elsewhere... probably not
 
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Kyle / MrHeeHo

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Will there be a teardown? According to this Twitter user they found fake parts in a Hifiman product (or at least parts different than what's advertised) and I'm curious if the case is the same with this product

The thread goes on much longer and compares more parts. I can't translate unfortunately, I had to run these through people that can.
 
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stalepie

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How does one know the chip has been "polished and reprinted" (as Google Translate says)? "The mark of ◎ is collapsed at 901s "
I have trouble seeing much difference.
 

restorer-john

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The mould stamped depression depth is either diminished or gone altogether when they are re-surfaced. It's commonly a give away.
 

Wombat

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When
The unit does not have stock tubes. It has aftermarket tubes, Mullard/RTC 5654 (6AK5W), that were included when I bought it.

According to one Amazon review, those are "the best."

For optimum performance of tubes when changed the bias should be adjusted accordingly. Tube rollers mostly can't do this so their comparisons are flawed and rather random.
One could say this about many IC swaps, also.

Tube-rollers use-up(waste) many fine NOS tubes, that are becoming more scarce, as they use them to achieve a 'tone control' setting they prefer.

Tube guitar-amp users do this also and their audience really couldn't hear the difference, in use. o_O
 
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Wombat

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I will not pretend to have any understanding of how tubes work their black magic, but could the non-stock tubes amplify the signal more than intended until it runs into a ceiling imposed by other components?

Tubes don't work black-magic. Period.

No issues if they are operated within their design parameters.
 

Jimster480

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I read at one point that tubes were desirable due to how "nicely" they clipped. While this is obviously subjective, does this apply to this clipping scenario?
It might be the reason that they are clipping lol.
That's welcome by me, it's up to Amir how sick he is of reviewing DACs. :)
you are the owner of this product right?
 
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amirm

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That's welcome by me, it's up to Amir how sick he is of reviewing DACs. :)
Thanks. I just tore it down and took some pictures. I should be able to upload it tomorrow.
 
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amirm

amirm

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It is still open. And no precision was required. Just a big hammer!!! :D

As soon as I save up some money, I plan to get one of these for future teardowns:

 

RayDunzl

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There was a lot of noise trapped in those devices.

Where did the smoke go?

Here's a Big Boy...

 
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