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post #16 of 24

Oh I said it wasn't rigorous. 

 

The tape machine had been aligned and checked out for flat response.  The phono  amp also checked a year or so later for its conformance to the spec RIAA curve. The first test phono amp was within 1 db over the whole range when tested at the later date.  It has been a long time, but as I recall it drooped a bit being about 1-db down at 20 khz with the droop starting around 13 khz.  It had some smaller wiggles lower in frequency around the center part of the RIAA filter.  And of course drooped  starting at about 30 hz and below.  I had no way to do a good check thoroughly with the cartridge.  A test record with spot test frequencies showed it to be pretty good with a tiny bit of lift at 18 khz and 20 khz the exact amounts I don't remember.  But having used more than one test record those don't even agree with each other at least not those available at a consumer level.  So the reel was at least in good working order, and spec'd out okay on response.  The TT system not including cartridge was pretty good.  The CD was fine. 

 

The sources were CD which were re-releases of analog material.  Some may have been the same master, some (likely most) probably weren't the same master just stuck on CD.  Reels were pre-recorded reels available commercially some even in higher tape speeds.  Ditto the LP, as to the change in mastering other than getting the same numbered releases we obviously had no control over that.  

 

The least precise part of the test was setting levels.  We had to do that by ear, and again the LP was always hardest to do that for.  It generally seemed to be either gain ridden or compressed.  It just was harder to match levels of other sources to LP.  I am pretty sure we more or less got levels within 3 db, and probably more like 1 db.  That in itself would invalidate it vs a truly controlled test at least in terms of sound quality.  The test was never blind.  

 

If someone wanted to say LP could be transparent, I wouldn't disagree too strongly.  With proper design, excellent cartridge and an RIAA curve that not only met the proper curve, but corrected for deficiencies in the cartridge as well as loading the cartridge precisely for flattest response it might be transparent.  But LP playback and mastering is a whole lot less likely to be fully transparent.  Lots more places to get it wrong.  And I believe various mastering techniques were employed making full transparency far less likely just from EQ and gain changes for going to vinyl pressing.  

 

So just listening with some precautions that nevertheless fall far short of being a perfect match between the 3 commercial sources, reels and CDs sounded pretty similar and LP stuck out like a sore thumb due to apparently different EQ.  The later listening session with fewer recordings on another system yielded the same impressions though I never had access to each piece of equipment to confirm its operating parameters. 

 

Not disagreeing that the vinyl was different, just questioning the cause.  The observation that there is a difference points misleadingly to vinyl itself,  when as you know it's the entire chain from master to phono preamp output, and there's a lot to be different in there.  The vinyl itself isn't the largest cause for the difference at all.

 

Which is mostly my point.  Your chances of transparent LP playback with commercial material is much less likely.  Since all of these other sources of difference are in that playback chain due to vinyl being the transfer medium, I still blame vinyl for the difference.  


Edited by esldude - 6/17/13 at 11:18am
post #17 of 24
Quote:
Originally Posted by jaddie View Post

You are referring to the 1951 Chicago Symphony sessions recorded at Orchestra Hall, and recorded at Universal Recording across town where the recordings were made by legendary Bill Putnam.  While well known that an equalized phone line was used, it is unlikely that it was bare wires on ceramic insulators.  It is, however, entirely possible to equalized what was then probably 22ga twisted pair for flat response to 15KHz or better over that distance, even including a trip to the central office first.  The equalizer would have been passive, followed by about 20 to 25dB of flat amplifier gain stage. The clue to the fact that they were standard equalized phone lines is that those recordings are noted for the slight phone line crackle. Phone companies discovered early in the 1900s that twisted wire pairs had much higher noise immunity, so that system was adopted and would have been standardized easily by 1951, but line noises was always a problem for high quality audio transmission.  Mercury also experimented with 3-track 35mm mag film with good results because the tracks were wider than tape, the base is thicker for less print through, and the speed was slightly faster at 18 inches per second (90 feet per minute is standard 35mm speed at 24fps).   Their vans included full-track mono Ampex 300 machines along with 35mm magnetic 3-track machines.  

Don't recall Bill Putnam's name, but you may be right.  It was the first Mercury Living Presence Mono recordings.  I think they started with MG50000 and counted up from there.  I don't recall if it was one or a few that were recorded remotely.  Most were done with the recording vans using Ampex 300 machines as you said.  

 

I might be wrong about the bare wires, but have some memory of an old magazine article with a picture, and I believe the very first LP cover also stated they used spaced bare wire on ceramic insulators which I thought odd at the time.  I would have expected twisting of the wires as well. Seem to remember that was done to adjust for an impedance match over the length of the wire. Perhaps if someone happens to have the cover for this they could look and see what it says about how it was recorded.  I no longer have these LP's.   And perhaps I am remembering this wrong.  I also seem to remember that they worked for and achieved flat response to 15 khz and no more.  

 

I also had the later 35mm recordings in some stereo releases.  These were some very fine recordings.  I no longer have LP's, but do have the CD re-releases of several of the 35mm recorded Mercury's.  


Edited by esldude - 6/17/13 at 11:44am
post #18 of 24
Quote:
Originally Posted by esldude View Post

Oh I said it wasn't rigorous. 

 

The tape machine had been aligned and checked out for flat response.  

As you might imagine, there are several ways to do that, all of which will affect the end result significantly, as will differences in track formats.

Quote:

Originally Posted by esldude View Post

 The phono  amp also checked a year or so later for its conformance to the spec RIAA curve. The first test phono amp was within 1 db over the whole range when tested at the later date.  It has been a long time, but as I recall it drooped a bit being about 1-db down at 20 khz with the droop starting around 13 khz.  It had some smaller wiggles lower in frequency around the center part of the RIAA filter.  And of course drooped  starting at about 30 hz and below.  I had no way to do a good check thoroughly with the cartridge.  A test record with spot test frequencies showed it to be pretty good with a tiny bit of lift at 18 khz and 20 khz the exact amounts I don't remember.  But having used more than one test record those don't even agree with each other at least not those available at a consumer level. 

What you observed is the reason you needed to use the test record without RIAA EQ.  That eliminates several errors.  You cannot confirm the total response by measuring just the preamp, the cartridge has its own response issues, and it can be affected by the loading of the front end of the preamp and cabling.  This is one instance where wire capacity does make a difference.  I've measured many cartridges, they all vary and several are highly sensitive to loading issues.

 

Quote:

Originally Posted by esldude View Post

 

The sources were CD which were re-releases of analog material.  Some may have been the same master, some (likely most) probably weren't the same master just stuck on CD.  Reels were pre-recorded reels available commercially some even in higher tape speeds.  Ditto the LP, as to the change in mastering other than getting the same numbered releases we obviously had no control over that.  

That's sort of what I expected.  You've got three totally different audio paths there, which is what you were comparing. You might make a few guesses about the original LP itself, but your unconfirmed playback system would negate the observations.  The tape chain would be the least known, unless there's some detail on the box.  Most were duplicated at high speed, which takes it's own toll.  Very few were duplicated real time, but even if they were, they would be at least two generations removed form the master because the wouldn't duplicate from the original master.  Too many plays! There would be a dub master, possibly at a different speed than the original.  The dupes would most likely be at 7.5 IPS, with the master at 15 IPS.  

 

Quote:

Originally Posted by esldude View Post

If someone wanted to say LP could be transparent, I wouldn't disagree too strongly.  With proper design, excellent cartridge and an RIAA curve that not only met the proper curve, but corrected for deficiencies in the cartridge as well as loading the cartridge precisely for flattest response it might be transparent.  But LP playback and mastering is a whole lot less likely to be fully transparent.  Lots more places to get it wrong.  And I believe various mastering techniques were employed making full transparency far less likely just from EQ and gain changes for going to vinyl pressing.  

Agreed, the mastering process is way out of control and unknown.  From the standpoint of the technology, tape would be far more wild, though.  Home playback tape machines were hardly ever calibrated, or  even capable of proper calibration, and required on going maintenance far beyond what even the most basic LP playback required.  High speed duplication was erratic at best, and often not carefully done at all.  

 

 

Quote:
Originally Posted by esldude View Post

 

So just listening with some precautions that nevertheless fall far short of being a perfect match between the 3 commercial sources, reels and CDs sounded pretty similar and LP stuck out like a sore thumb due to apparently different EQ.  The later listening session with fewer recordings on another system yielded the same impressions though I never had access to each piece of equipment to confirm its operating parameters. 

The problem here is that unless you were working with recordings all from the same era and label, there should not have been the  consistent difference you observed.  This points to an issue with the audition system or method.  I'm sure the observations were correct, but I'm not at all convinced it was the vinyl media or mastering at fault.  Again, I have done the controlled test: identical master feed to both vinyl and CD, no mastering processing on either, careful calibration of the playback system, and the response differences were gone.  

 

 

Quote:
Originally Posted by esldude View Post

Your chances of transparent LP playback with commercial material is much less likely.  Since all of these other sources of difference are in that playback chain due to vinyl being the transfer medium, I still blame vinyl for the difference.  

I guess I'm just nit-picking.  There's nothing about the vinyl chain itself that causes this, but there are lots of choices made in the process that can.  When comparing and auditioning, there's a strong need for precise calibration, or the results may be skewed.  

post #19 of 24
Quote:
Originally Posted by esldude View Post

Don't recall Bill Putnam's name, but you may be right.  It was the first Mercury Living Presence Mono recordings.  I think they started with MG50000 and counted up from there.  I don't recall if it was one or a few that were recorded remotely.  Most were done with the recording vans using Ampex 300 machines as you said.  

Putnam founded Universal Recording, and went on to found UREI.  Google him, interesting guy.  I visited Universal Recording in the early 1970s, quite a place.

 

Is this the record we're talking about?  You can zoom in on the back, nothing about phone lines, though.

 

 

 

 

Quote:

Originally Posted by esldude View Post

I might be wrong about the bare wires, but have some memory of an old magazine article with a picture, and I believe the very first LP cover also stated they used spaced bare wire on ceramic insulators which I thought odd at the time.  I would have expected twisting of the wires as well. Seem to remember that was done to adjust for an impedance match over the length of the wire. Perhaps if someone happens to have the cover for this they could look and see what it says about how it was recorded.  I no longer have these LP's.   And perhaps I am remembering this wrong.  I also seem to remember that they worked for and achieved flat response to 15 khz and no more.  

The problem with spaced wires on porcelain insulators would be that in a city, there wouldn't be enough physical space for all the circuits required.  Spacing wires would change the characteristic impedance, but that's only a matter of interface, not so much in transmission of audio.  Once the phone company started installing lots of circuits they had to go to twisted pair, or it just would't physically fit.  Initially the wire gage was larger, I think 18ga, then 20, then 22.  I think they ended up at 24, possibly 26 in some places.  There's no possibility that Mercury paid to have a special spaced porcelain line installed, that would have cost more than the entire session.

post #20 of 24
It doesn't surprise me at all that a reel to reel might sound more like a CD than an LP.

By the way, MLP records are probably among the best to do a test like this with. The CDs say that the mastering consisted of a straight transfer from the original master tape... no noise reduction, compression or sweetening.
Edited by bigshot - 6/17/13 at 1:58pm
post #21 of 24
Quote:
Originally Posted by bigshot View Post

It doesn't surprise me at all that a reel to reel might sound more like a CD than an LP.

It surprises me because the reel would be two generations away from the master at least, and potentially a different speed at track format, ignoring duplication issues.  The vinyl should be either a direct transfer from the master or 1 generation removed.  

 

Those 1/4 track stereo reels were not sterling...perhaps these were full track mono though.  There would be a fringing issue during playback on any stereo machine which probably would not be compensated for (doubt many would know about that today!)

post #22 of 24
Quote:
Originally Posted by bigshot View Post

By the way, MLP records are probably among the best to do a test like this with. The CDs say that the mastering consisted of a straight transfer from the original master tape... no noise reduction, compression or sweetening.

That would explain the nice CD transfer.  Too bad we don't know everything about the LP master...

post #23 of 24
Quote:
Originally Posted by jaddie View Post

Agreed, the mastering process is way out of control and unknown.  From the standpoint of the technology, tape would be far more wild, though.  Home playback tape machines were hardly ever calibrated, or  even capable of proper calibration, and required on going maintenance far beyond what even the most basic LP playback required.  High speed duplication was erratic at best, and often not carefully done at all.  

 

 

The problem here is that unless you were working with recordings all from the same era and label, there should not have been the  consistent difference you observed.  This points to an issue with the audition system or method.  I'm sure the observations were correct, but I'm not at all convinced it was the vinyl media or mastering at fault.  Again, I have done the controlled test: identical master feed to both vinyl and CD, no mastering processing on either, careful calibration of the playback system, and the response differences were gone.  

 

 

I guess I'm just nit-picking.  There's nothing about the vinyl chain itself that causes this, but there are lots of choices made in the process that can.  When comparing and auditioning, there's a strong need for precise calibration, or the results may be skewed.  

I am well aware of everything you wrote about here.  Wasn't necessarily aware of all of it at the time, as this was quite a few years back.  It was no more than I said it was.  Commercially available recordings and a comparison of the formats.  We did not expect LP to be so clearly different. I already said it wasn't rigorous.  I don't even own LP hardware or software anymore.  I used what I had at the time as carefully as I could at the time.  

post #24 of 24
Quote:
Originally Posted by jaddie View Post

The problem with spaced wires on porcelain insulators would be that in a city, there wouldn't be enough physical space for all the circuits required.  Spacing wires would change the characteristic impedance, but that's only a matter of interface, not so much in transmission of audio.  Once the phone company started installing lots of circuits they had to go to twisted pair, or it just would't physically fit.  Initially the wire gage was larger, I think 18ga, then 20, then 22.  I think they ended up at 24, possibly 26 in some places.  There's no possibility that Mercury paid to have a special spaced porcelain line installed, that would have cost more than the entire session.

Yes, that is the one.  I had it and the next several in the series.  I purchased them supposedly in unplayed condition at an estate sale.  They looked to be unplayed.  

 

So perhaps I saw the spaced wire info in the magazine article at some later time.  Long time ago, and my memory isn't perfect.  Even with twisted pair phone lines over a couple miles the sound was surprisingly good when one considers how awful some other recordings with far more modern equipment turn out to be.  


Thanks for posting the hi-rez photo of the back cover.  I sold those a bit over a decade ago when I got out of analog gear altogether. 

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