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Recommendation for USB audio interface, Low output impedance, low absolute noise level
googlebot
post Mar 31 2012, 13:00
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I have a pair of excellent IEMs with 119 dB SPL/mW sensitivity, that aren't too easy to drive on conventional higher-impedance headphone outputs (2-way balanced armature, <27 ohms). I'm looking for a desktop USB interface with manual volume control, a headphone jack with low output impedance (~0 ohms), and a low absolute noise floor (due to the low sensitivity). Many manufacturers post their SNR figures, which do not help me decide, whether the latter requirement is really fulfilled. For example, with the IEMs plugged into an onboard Realtek ALC261 output, which has got a SNR close to 100dB, I can hear the SSD working.

I had a look at the E-MU 020x devices, which seem to be great, but their 22 ohm headphone output jack looks like a constraint for the intended usage.

Could you recommend anything else?

*** Edit: I just noticed: Sorry, wrong forum. Please move to 'Audio Hardware' if you find the time.

This post has been edited by googlebot: Mar 31 2012, 13:14
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googlebot
post Apr 12 2012, 19:36
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After extensively testing the Yulong U100 I can report that I'm more than happy with it. Sound and both relative and absolute SNR are exceptional.

IEMs provide an opportunity to drive 16 bit to its limits without damaging your ears, since a good portion of the baseline noise, that you have to live with in an usual listening environment, is kept out and you're feeding sound directly into your ear canal. Even with the maximum, pain-free listening level, recordings (and sometimes their recorded noise) seem to ascend from a floor of absolute silence - or the sound of my blood circulation (but my brain usually takes care of filtering out the latter).

The Westone UM2 has got an impedance curve like a rollercoaster. The U100 doesn't seem care, great bass, no perceivable roll-off whatsoever.
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stephan_g
post Apr 18 2012, 21:03
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Implementation is king when it comes to analog and mixed-signal components, onboard sound included. Extraneous noises on the headphone out usually are a result of bad routing (typically ground, including a connection of audio ground to case ground at the front panel) or inadequate supply filtering, reflecting time and space constraints. When time to market is critical, manufacturers usually have bigger problems than getting audio right.

It is, however, definitely possible to make onboard sound with a headphone output that's dead quiet - I know because I have one here, using an ALC262 (Fujitsu-Siemens D2587 board). OK, output resistance is kinda high (somewhere in the 47..100 ohm territory or so, sadly I misplaced my Y-dapter), and the most sensitive IEMs I can offer are SE420s, but at least I can tell that there is nothing severely wrong. (Like, say, the annoying ticking noises my old ClipV2 showed in Rockbox.)
Sometimes muting all the inputs is sufficient to get things quiet.
QUOTE (googlebot @ Apr 12 2012, 19:36) *
IEMs provide an opportunity to drive 16 bit to its limits without damaging your ears, since a good portion of the baseline noise, that you have to live with in an usual listening environment, is kept out and you're feeding sound directly into your ear canal. Even with the maximum, pain-free listening level, recordings (and sometimes their recorded noise) seem to ascend from a floor of absolute silence - or the sound of my blood circulation (but my brain usually takes care of filtering out the latter).

Even if filtered out, it's still there and covering things up though. (Case in point: The E6 still isn't considered entirely noise-free with very sensitive IEMs, yet you didn't notice.) My blood noise sometimes bothers me even with conventional headphones, which is why I tend not to listen to that much music in the summer (when temperatures and consequently blood pressure are high, not to mention outside noises coming in through open windows). AFAIK it takes deep-sealing IEMs like ER-4Ps to get rid of most of that, including noises while eating (super annoying, too). (ER-4s have been around since 1991? I did know they were available in '96. So it took over 15 years for the technology to become anything near mainstream.) Too bad I only have one ear canal compatible with triflanges at best.

I prefer a quiet environment and open headphones any day of the week. Whenever it's noisy, IEMs obviously are the best thing since sliced bread, and I was awfully glad when I got my first ones (public transport finally got bearable even with a bunch of noisy kids).

This post has been edited by stephan_g: Apr 18 2012, 21:03
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Nessuno
post Apr 18 2012, 22:00
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QUOTE (stephan_g @ Apr 18 2012, 22:03) *
Too bad I only have one ear canal compatible with triflanges at best.


Ever tried to reverse the inner, bigger flange? A little trick that works like charm for me. smile.gif


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