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Old 2nd March 2011, 12:09 AM   #10331
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Originally Posted by PMA View Post
That's right. I mean that LP, which is not perfect at all, may bring 'something' that is more acceptable to human ear than technically clinically reproduced sound. Both are far away from original sound, but LP may have imperfections that are more tolerable (for human perception) than plain technically correct reproduction.
Yeah, I agree with you. My analog system isn't the best - a vintage Thorens TD25mkII with a modified Rabco SL-8E linear tracking tonearm. I use the tape outs on tube phono preamp in an old Counterpoint SA-3 peamp for my phono preamp which sounds nice.

But, there is an easiness and musicality to the sound on good LP's that I don't get from any digital. Maybe it's distortion but don't know. With some tweeks, a better cart and phono preamp it could sound a lot better, I'm sure. But my SACD playback sounds cleaner and overall better at the present. I also hate messing with my LP rig - a tweakers dream and my nightmare. I can never leave the VTA, tracking weight or azimuth alone.

I'm waiting for the next analog format to come out ... Ha, Ha

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Edit: wow, the post I answered disappeared
Sorry, I deleted that cause your two posts above answered my question. I wasn't quit sure what we were discussing here when I first tuned in this morning.
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Last edited by Johnloudb; 2nd March 2011 at 12:11 AM.
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Old 2nd March 2011, 02:14 AM   #10332
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It is NOT distortion, it is in spite of some audible distortion. This can be proven by listening to a test record with the SAME music on both channels, BUT one side is digitized before being cut on the record. This has been done, and demonstrated at CES, decades ago. The same problem can be found even better by listening to the 30ips full track master tape vs a digitized version of the same master tape by just adding the AD-DA converter to the output of the master tape recorder. You know, A or B. Here, ONLY the digital problems are ADDED. Please everyone, try before you decide.
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Old 2nd March 2011, 02:44 AM   #10333
Pano is offline Pano  United States
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But there have been so many of the A vs D test with null results - even among the pros - that what is one to think?
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Old 2nd March 2011, 02:47 AM   #10334
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Originally Posted by john curl View Post
It is NOT distortion, it is in spite of some audible distortion. This can be proven by listening to a test record with the SAME music on both channels, BUT one side is digitized before being cut on the record.
"Proven" how? By using the usual sighted dog and pony show "demonstrations"?

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Old 2nd March 2011, 03:28 AM   #10335
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Yes, I like to know what I am listening to.
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Old 2nd March 2011, 03:33 AM   #10336
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Originally Posted by john curl View Post
It is NOT distortion, it is in spite of some audible distortion. This can be proven by listening to a test record with the SAME music on both channels, BUT one side is digitized before being cut on the record. This has been done, and demonstrated at CES, decades ago. The same problem can be found even better by listening to the 30ips full track master tape vs a digitized version of the same master tape by just adding the AD-DA converter to the output of the master tape recorder. You know, A or B. Here, ONLY the digital problems are ADDED. Please everyone, try before you decide.

It's hard for me now to repeat the experiment, I carefully lined up the same passage from side A and side B and there were simple amplitude differences at some frequencies of more than 3dB. This is not simply interposing and A/D D/A in the chain. BTW I still couldn't tell a difference between the two.
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Old 2nd March 2011, 03:43 AM   #10337
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We use 10's of thousands of high quality relays and reed switches on the test floor, I can't say that I ever saw one that won't do >-120dB. BTW a dead zone in the feedback path would put a hole in your Vos distributions, never saw that, ever in 38yr. We've been making amplifiers with 25uV guaranteed offset for 30yr. and they are all tested at a rate of hundreds an hour with several relays in series with each input.

Ed, I simply speak from literally 100's of man years of collective experiece, the stuff our guys have to measure would tax anyone's abilities. No one I know has ever seen a dead zone in a resistor or switch (that was not broken). Chopper amps now have 1uV offsets, we do test them.
I am sure that if you had the problem you would have solved it. I believe the way you use switches and relays you do not have the problems, the difference may show up with specific preconditioning and measurement techniques. I suspect there are quite a few conditions required to make the problem show up, except for the obviously broken cases. I am currently working on improving my test setup. If I get interesting repeatable data I will share it.

My last try at an A/B test used a 6 position switch with positions 1 & 2 known as A & B the other four were mixed and neither the operator of the switch or the listeners knew if they were connected to A or B. The results showed certain switch positions stood out not the devices under test. Measurements done after the listening tests showed the distortion change was due to the switch not the devices under test.

I have now found this limiting problem two ways. Once when I was testing cables I put in a forward reverse switch and found flipping the switch showed differences that stayed the same even when the cable under test was flipped. The conclusion was the switch added more distortion than the cable. (Not too unreasonable I think). The second time was doing the A/B test just mentioned. So it seems reasonable to devise a switch specific test.

There are two ways I am trying. One is using a Wheatstone bridge with a single switch in one leg. I expect to try 100 ohm to 10k both sides with an excitation voltage of 100mv. Then I may play with resistor values in the bridge. The second method is to apply 100nv or less from a 1khz triangle or sine wave to the device under test. The load will be the non-inverting input of 4 opamps in parallel. The first stage feedback resistors will be 1K into 10 ohms. This will be high passed around 100 and low passed around 10k to try and limit the noise a bit. This is the same test I plan to use for testing resistors under 1k for similar issues.

Your expectation is I will find nothing. Mine is I will find something and it often will not be what I am looking for. I presume you find nothing upsetting about the experiment.

Last edited by simon7000; 2nd March 2011 at 03:59 AM.
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Old 2nd March 2011, 03:59 AM   #10338
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Yes, I like to know what I am listening to.
Then I would suggest you refrain from using the word "proven."

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Old 2nd March 2011, 04:12 AM   #10339
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Originally Posted by john curl View Post
It is NOT distortion, it is in spite of some audible distortion. This can be proven by listening to a test record with the SAME music on both channels, BUT one side is digitized before being cut on the record. This has been done, and demonstrated at CES, decades ago. The same problem can be found even better by listening to the 30ips full track master tape vs a digitized version of the same master tape by just adding the AD-DA converter to the output of the master tape recorder. You know, A or B. Here, ONLY the digital problems are ADDED. Please everyone, try before you decide.
I think that digital technology has improved since the decades ago that your CES demonstration was performed.

I think Richard Brice's test was better designed; i.e., comparing each of the vinyl and CD results to the ORIGINAL master tape. The CD sounded more like the ORIGINAL. However, he liked the vinyl copy better than the original. It is very easy to audition his processing by copying his demo files to a USB flash drive and playing through a Blu-ray player capable of playing such files.

I downloaded the music samples from his site, and did prefer the one using his process that "conformed" his recordings to Blumlein's recommendations. Even though they were in MP3 format, I found the processed files to be more natural sounding. They relieved a bit of that digital stress factor.

Last edited by pooge; 2nd March 2011 at 04:14 AM.
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Old 2nd March 2011, 05:50 AM   #10340
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Not really. Less that I would have predicted. In the last year or so, I have worked with some of the best digital playback technology available anywhere. Doesn't impress me.
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