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Any Vinyl ABX Test via ADC/DAC been performed?


I was searching around to see if anyone had done a decent ABX test of Vinyl vs the same equipment directed via a ADC and straight to a DAC. So I'd envisage the two virtually identical setups as being a high quality turntable via a decent pre-amp, one going via ADC straight out to a DAC and another going direct to an amps line in.

I'd read somewhere some of these tests have failed by people being able to hear a characteristics switching "clunk" between the two sources, so I guess two sets of equipment would fix that.  I'm thinking decent equipment so that vinyl fans can't claim if you only had a better turntable etc. Maybe an album that was created fully analogue to eliminate that potential complaint.

As a non-Nyquist denier, no one should be able to tell the difference. But it would be nice to have a clean test like this to show there is no inherent sound/signal loss due to being digital at some point.

I have only ever seen a test like this for 16 bit vs 24 bit audio test, where people couldn't tell the difference.

Or have I just missed such a test....

Re: Any Vinyl ABX Test via ADC/DAC been performed?

Reply #1
Needle wear.
Format: FLAC

Re: Any Vinyl ABX Test via ADC/DAC been performed?

Reply #2
I'm sure it's been done...   And, I assume you're talking about comparing analog vinyl to a digitized copy of the same vinyl record?      It's  technically a violation of forum rules to say this, but anybody can hear the difference between a vinyl record and the CD (or MP3).     The whole reason I (and most of the world) switched to CDs in the 1980s was the vastly superior sound of the CD!

"Vinyl fans" will agree there's a difference and they may prefer the (technically inferior) sound of the record.

...I'd expect the (properly recorded) digital copy of the record to sound identical to the record.

Except when I digitize records I "clean them up" by removing the "snap", "crackle", and "pop" as much as possible and sometimes I EQ older dull-sounding records to bring-up the highs.   So the digital copy is better than the original vinyl, but rarely as good as a original-factory CD.


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It think the difficulty would be synchronizing the playback.  If one is always leading and one is always lagging you'd know when it's switched and you might be able to tell if it's A or B.

Quote
So I'd envisage the two virtually identical setups as being a high quality turntable via a decent pre-amp, one going via ADC straight out to a DAC and another going direct to an amps line in.
Presumably you'd have two sets of speakers so you might hear the sound direction changing, and just moving speaker position can change the sound.

Quote
I'd read somewhere some of these tests have failed by people being able to hear a characteristics switching "clunk" between the two sources, so I guess two sets of equipment would fix that. 
You'd probably need a way to mute the audio during switching (or not-switching) and then whoever is doing the switching can simply unplug and replug-in when they switch (and when they don't switch) instead of actuating a mechanical switch.   Or, you could have an extra unconnected switch that makes the same mechanical/acoustic noise, and again you'd mute the audio while switching or pretending to switch (to eliminate any electrical switching noise).

Re: Any Vinyl ABX Test via ADC/DAC been performed?

Reply #3
Using two nominally identical analogue sources cannot work. You cannot expect to find a pair of cartridges and a pair of LP pressings that are identical.

Such a test should be conducted by using a single source and switching a ADC/DAC in and out of circuit. It shouldn't be rocket science to achieve a silent switchover.

I seem to recall that a test of the audibility of a ADC/DAC in circuit was done many years back with negative results (ie. nobody could tell a difference). I don't recall if the source was analogue, though.

Re: Any Vinyl ABX Test via ADC/DAC been performed?

Reply #4
Using two nominally identical analogue sources cannot work. You cannot expect to find a pair of cartridges and a pair of LP pressings that are identical.

Such a test should be conducted by using a single source and switching a ADC/DAC in and out of circuit. It shouldn't be rocket science to achieve a silent switchover.

I seem to recall that a test of the audibility of a ADC/DAC in circuit was done many years back with negative results (ie. nobody could tell a difference). I don't recall if the source was analogue, though.

Sounds good. I guess the delay could be taken into account by always re-cueing (maybe randomly) the record during every switch.
Did you have any details of this test?



Re: Any Vinyl ABX Test via ADC/DAC been performed?

Reply #7
I did an informal test with the local audiophile club (several vinylphiles).
TT > dual output phono preamp >output1> amp input 1, output2> ADC/DAC loop > amp input 2. Instant, noiseless switching between amp in 1& 2. The biggest issue by far, was matching V levels > amp, using a test LP with tones. I would not submit to AES, nor guarantee it was matched at 0.1V precision. Single blind at best.
No one could tell the difference. The very last sequence, a vinylphile, disbelieving he could not tell difference, swore the last play was vinyl. I got up, walked away from setup without touching, had him sit in tester chair to see what he though 100% sure was vinyl....was actually "digital". Funny stuff.
I subsequently acquired a AVA ABX box, so at some point can repeat test. It's not a high priority, in fact extremely low. Precisely matching levels using vinyl is still tricky.
Loudspeaker manufacturer

Re: Any Vinyl ABX Test via ADC/DAC been performed?

Reply #8
I'm sure it's been done...   And, I assume you're talking about comparing analog vinyl to a digitized copy of the same vinyl record?      It's  technically a violation of forum rules to say this, but anybody can hear the difference between a vinyl record and the CD (or MP3).     The whole reason I (and most of the world) switched to CDs in the 1980s was the vastly superior sound of the CD!

"Vinyl fans" will agree there's a difference and they may prefer the (technically inferior) sound of the record.

...I'd expect the (properly recorded) digital copy of the record to sound identical to the record.

Except when I digitize records I "clean them up" by removing the "snap", "crackle", and "pop" as much as possible and sometimes I EQ older dull-sounding records to bring-up the highs.   So the digital copy is better than the original vinyl, but rarely as good as a original-factory CD.


-----------------------------------------------------------------------------------------
It think the difficulty would be synchronizing the playback.  If one is always leading and one is always lagging you'd know when it's switched and you might be able to tell if it's A or B.

Quote
So I'd envisage the two virtually identical setups as being a high quality turntable via a decent pre-amp, one going via ADC straight out to a DAC and another going direct to an amps line in.
Presumably you'd have two sets of speakers so you might hear the sound direction changing, and just moving speaker position can change the sound.

Quote
I'd read somewhere some of these tests have failed by people being able to hear a characteristics switching "clunk" between the two sources, so I guess two sets of equipment would fix that. 
You'd probably need a way to mute the audio during switching (or not-switching) and then whoever is doing the switching can simply unplug and replug-in when they switch (and when they don't switch) instead of actuating a mechanical switch.   Or, you could have an extra unconnected switch that makes the same mechanical/acoustic noise, and again you'd mute the audio while switching or pretending to switch (to eliminate any electrical switching noise).

Want a silent switchover? Just get a basic DJ battle-/club mixer with two stereo channels. Use the crossfader for a quick, seamless and silent switch between sources. Though it will still be necessary to stop or mute the audio before switching because depending on the fader curve, there might be a small dip or raise in volume while operating the fader. (Good news is we have channel faders and cue buttons to do just that.) :) Not to speak of the small delay the A/D→D/A conversion might introduce, which might just be enough to cancel out/amplify some frequencies as another "tell" you're just operating the crossfader.

Re: Any Vinyl ABX Test via ADC/DAC been performed?

Reply #9
I did an informal test with the local audiophile club (several vinylphiles).
TT > dual output phono preamp >output1> amp input 1, output2> ADC/DAC loop > amp input 2. Instant, noiseless switching between amp in 1& 2. The biggest issue by far, was matching V levels > amp, using a test LP with tones. I would not submit to AES, nor guarantee it was matched at 0.1V precision. Single blind at best.
No one could tell the difference. The very last sequence, a vinylphile, disbelieving he could not tell difference, swore the last play was vinyl. I got up, walked away from setup without touching, had him sit in tester chair to see what he though 100% sure was vinyl....was actually "digital". Funny stuff.
I subsequently acquired a AVA ABX box, so at some point can repeat test. It's not a high priority, in fact extremely low. Precisely matching levels using vinyl is still tricky.

Would you mind describing in detail your setup for the ADC / DAC loop? I'm also considering putting together a tester kit to perform a vinyl ABX test.. Also, how did you calibrate the volume? (I assume you did something like a frequency-wise volume calibration, and used an EQ to achieve a match?) Where did you get your test LP with tones that you used for volume calibration?

Too many questions maybe, but I'd like to recreate the same experiment. Thanks!

Re: Any Vinyl ABX Test via ADC/DAC been performed?

Reply #10
It was yrs ago, but from memory:
Would you mind describing in detail your setup for the ADC / DAC loop?
SRC2496 Has all in/out/gain controls needed.

Also, how did you calibrate the volume? (I assume you did something like a frequency-wise volume calibration, and used an EQ to achieve a match?)
Used multi-meter, measured voltage at preamp out (used active speakers), for each input 1 & 2. No EQ needed or involved. It's a AD/DA of the exact same signal. Only difference would be the 22k low pass filter on one.

Where did you get your test LP with tones that you used for volume calibration?
Soundcraftsmen test tone LP
The problem is the variability of LP playback getting a precise V match, even with max cleaning, etc.
Don't expect an AES submittal anytime soon.

cheers,

AJ
Loudspeaker manufacturer

Re: Any Vinyl ABX Test via ADC/DAC been performed?

Reply #11
It was yrs ago, but from memory:
Would you mind describing in detail your setup for the ADC / DAC loop?
SRC2496 Has all in/out/gain controls needed.

Also, how did you calibrate the volume? (I assume you did something like a frequency-wise volume calibration, and used an EQ to achieve a match?)
Used multi-meter, measured voltage at preamp out (used active speakers), for each input 1 & 2. No EQ needed or involved. It's a AD/DA of the exact same signal. Only difference would be the 22k low pass filter on one.

Where did you get your test LP with tones that you used for volume calibration?
Soundcraftsmen test tone LP
The problem is the variability of LP playback getting a precise V match, even with max cleaning, etc.
Don't expect an AES submittal anytime soon.

cheers,

AJ
It was yrs ago, but from memory:
Would you mind describing in detail your setup for the ADC / DAC loop?
SRC2496 Has all in/out/gain controls needed.

Also, how did you calibrate the volume? (I assume you did something like a frequency-wise volume calibration, and used an EQ to achieve a match?)
Used multi-meter, measured voltage at preamp out (used active speakers), for each input 1 & 2. No EQ needed or involved. It's a AD/DA of the exact same signal. Only difference would be the 22k low pass filter on one.

Where did you get your test LP with tones that you used for volume calibration?
Soundcraftsmen test tone LP
The problem is the variability of LP playback getting a precise V match, even with max cleaning, etc.
Don't expect an AES submittal anytime soon.

cheers,

AJ
It was yrs ago, but from memory:
Would you mind describing in detail your setup for the ADC / DAC loop?
SRC2496 Has all in/out/gain controls needed.

Also, how did you calibrate the volume? (I assume you did something like a frequency-wise volume calibration, and used an EQ to achieve a match?)
Used multi-meter, measured voltage at preamp out (used active speakers), for each input 1 & 2. No EQ needed or involved. It's a AD/DA of the exact same signal. Only difference would be the 22k low pass filter on one.

Where did you get your test LP with tones that you used for volume calibration?
Soundcraftsmen test tone LP
The problem is the variability of LP playback getting a precise V match, even with max cleaning, etc.
Don't expect an AES submittal anytime soon.

cheers,

AJ

Many thanks for the reply! I'll take a look into this, and if I manage to run the tests on my own, will report back here..

Re: Any Vinyl ABX Test via ADC/DAC been performed?

Reply #12
Great comments, very informative.

My take away is that both formats will be distinguishable due to all those quirky things in LPs  getting in the way, except when in some special circumstances -  like ajinfla's test or vinyl's CD copies - the differences could be small enough to make it very difficult stablish the differences.

 
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