Crosstalk: digital more like Vinyl?

[f1eng]

Most of the time you don't have to compress the signal. So far in all the mastering we have done, we have found that what you really need to do is look at the recording and see if there are any trouble spots. A lot of the time you can increase groove depth slightly or decrease the overall signal by a db and avoid and limiting or compression altogether. Compression is/was often used though because record labels didn't want to pay the mastering engineer for the time to do this. These days recordings are often compressed because digital sounds best when you can use as many bits as are available- the normalizing process is used for the same reason. If you make an LP from such files, they have the same compression as the CD.



I have to take issue with this- we can record easily enough at 30KHz and play it back on some pretty pedestrian equipment (Technics Sl1200/ Grado Gold cart/ HK 430 receiver). The reason the LP seems to have less energy is that there is less phase shift due to filter effects (digital being bandwidth limited by comparison...); the human ear often converts phase shift problems into toanlity- I suspect that is what you are really hearing.



The only EQ involved is the RIAA. There is no process that equalizes low level signals differently from high level signals and this has nothing to do with the substrate. Compression of course will make quiet passages louder...



Again, I think you are working with some mythology here. Think back to the 1970s when CD-4 LPs were cut- they used a 50KHz carrier that was modulated in FM stereo for the additional 2 channels. After that, RCA developed a color video disk media that used a needle to track the signal- to do color you need 2MHz response. Almost any LP system has 30KHz bandwidth between record and playback and some, between record and playback exceed 40KHz. I don't know of any CD format that has got that sort of routine bandwidth yet. On top of that, LF bandwidth goes well below 20Hz. Today we recorded a direct-to-disk session (will be on Nero's Neptune, a Twin Cities local label); we were seeing information recorded in the grooves caused by a train passing the studio that was only about 8 Hz. I had no idea the mics could go that low... we don' t get this sort of bandwidth on the analog tape!

At any rate I find that while digital is supposed to be better in the bass, in practice I get better bass with the LP of the same recording. A lot has to do with how well your tonearm can track the cartridge, how dead the platter pad is relative to the LP, and how dead the plinth and platter are. If there are problems in any of these areas, bass playback will suffer.

Whether you need to compress to get onto LP depends on the dynamic range of the music you are recording. Small ensemble acoustic usually does not. Rock music doesn't either but large scale classical music has a higher dynamic range than any domestic hifi is capable of, including the LP, so compression is necessary though it doesn't need to be excessive. So yes, unless you are making LPs of symphonic music compression won't be necessary, just care to get the levels in the window, which you are obviously getting right.

CD can get away with less compression than LP without sound quality problems, so is potentially better for high quality classical recordings. High compression on recent CDs is because that is what people want, particularly for cars and earbuds in public not because it sounds better or is needed, CD has more dynamic range potential than LP, it is not a fault of the medium that some [EDIT:] people don't use it.
Getting the best out of the LP potential requires a different master than would get the best out of the CD potential, so if an LP and a CD -did- sound the same that would be lazy engineering

You certainly can record 30kHz on LP but only at limited maximum level, and it wears off the record PDQ. OTOH many of the finest sounding pickups can not play it back and those that can are usually into double figures of distortion at those freqencies. IMHO one of the things which I like best about LPs is the absence of HF sting. A bit like the old definition of a gentleman being somebody who knows how to play the bagpipes but doesn't, a good recording engineer is somebody who knows how to record extreme HF but doesn't - just a personal view.

Interesting that you recorded 8Hz on your direct to disc recording, fine microphones you have there!, though it could be at least partly structure borne pickup at that frequency. You seem to be unaware, however, how a seismic vibration pickup such as a cartridge works. No properly matched cartridge/arm could accurately play 8Hz.
FWIW a seismic pickup produces spurious/resonant output at frequencies below around 2x the natural frequency. In the case of a record player that is the Fn of the arm/cartridge mass on the cartridge compliance. Since in a well matched pairing this will be 20-25Hz anything lower than that will be still influenced by transucer resonance. At 8Hz the output will probably being exaggerated by 5x and be all over the place phase-wise. That is why the RIAA standard specifies a high pass filter. Of course without this filter there will be more LF output but it is amp and speaker overloading garbage and sensibly removed.

 

[RogerD]

OK Roger, there is no doubt that digital is "letterboxed" in as much as the frequency response is defined by the sampling frequency and, in principle the signal-to-noise ratio is defined by the bits, although with noise shaping and high sampling rates the noise can be moved away from the audible range increasing the signal to noise ratio.
CD is "letterboxed" such that the minimum frequency is DC and the maximum 22.05kHz. The signal to noise ratio is 96dB.
Analogue systems have fuzzy boundaries, but boundaries none the less. Since few people use reel-to-reel tape these days we are pretty well stuck with LP and FM radio for high quality analogue listening. Here in my home the highest quality analogue sound I ever hear is, and always has been, live BBC concert broadcasts. There used to be one at 7:30 every evening back in the day, and I used to tape them all for my education, keeping those I liked and recording over those I did not. FM stereo carries the difference information on a subcarrier and is limited by the signal to noise ratio of the broadcast medium such that its "letterbox" is slightly fuzzy, but is smaller that the CD letterbox. A parcel which would just fit through the FM stereo letterbox would easily fit through the CD letterbox with plenty of room all round.
With LPs it is less well defined and more fuzzy.

Just IMHO.

Thank you for your answer. I am sure others will have opinions.

I did some critical listening last night with a new CD I purchased last week,it is very nice.

http://www.amazon.com/Buenos-Aires-Madrigal-La-Chimera/dp/B0001K63R8

and just happened to want a change of pace and put on this...

http://www.amazon.com/Legend-Deluxe...1408299695&sr=1-4&keywords=bob+marley+limited

I must say the window seems to have closed somewhat,but my system especially my digital playback has improved in the last two weeks(I added another leg to the DAC for common ground). The perspectives of the two recordings are still different,as the digital seems to be closer focused than the analog. But with this M&A recording I can actually say that the presentation is wholly more like analog and is sharp without any irritating artifacts and the frequency range is very accurate. The seperation between instruments,notes and muscians is well defined and,may possibly be better than the analog CD. I am splitting hairs here. I stiil find that the analog version will reproduce ambient information(if it is there) more completely it seems(reverberation,echo,ect.)but the CD has qualities that I like very much and I never thought I would say that in a million years.
Your microphone observation is interesting. I was thinking that maybe the digital process captures a larger snapshot of the target microphone info because of the speed of the digital format, thus the different closer perspective. Though that might not be the case as physics would say there both the same. I'm sure the improvement in D/A converters has a lot to do with it.

So Frantz you might be right as there are enough variables present to make the difference. In my mind that is a wonderful thing.

 

[RogerD]

To get back to the OP's subject,somewhat I found this....

http://www.ambiophonics.org/Tutorials/UnderstandingAmbiophonics_Part1.html

"Humans can easily detect differences in reverberation time and the same applies to crosstalk cancellation. "

So is Uli actually using crosstalk cancellation and is crosstalk cancellation occuring somewhere in the analog chain,that doesn't occur in the digital domain?

Btw this quote from the link is exactly my experience with my psychoacoustic system...

"Conclusions. The reduction of localization distortion by Ambiophonics is such a profound change in sound reproduction that it can be easily heard on the most modest audio equipment. Indeed, if you use RACE crosstalk reduction on music reproduced by the 1-inch speakers built in to your laptop computer, you will hear the Ambiophonic stage. So large are the spatial and clarity/tonality changes produced by Ambiophonics that one accustomed to conventional stereo should allow the ear/brain several days to accommodate to Ambiophonic sound before evaluating it.

Ambiophonics can produce a “you-are-there” large ensemble experience rather than the cramped sense of “they are here” often delivered via the stereo triangle. It transports you to the recording site whereas conventional stereo seems to transport the instruments to your listening room. Listen to Ambiophonics long enough for your ear/brain to accommodate to the larger stage, improved imaging, greater clarity, and improved tonality. Listen long enough to get used to the sound. Then press the button that returns the sound to conventional stereo. The shock of the change will be like a slap in the face.

Recording engineers should use Ambiophonics with their studio monitoring speakers if they want to hear what the microphones hear. Just like home speakers, studio speakers used in a stereo triangle produce such localization distortion that an engineer cannot hear it when his microphone placement for a piano produces a piano that sounds 70-feet wide when reproduced on a system without localization distortion.

We are fortunate to have a legacy of a half century of stereo recordings—a cultural treasure. Stored on those CDs and LPs are a wealth of localization information and a level of clarity/tonality that we cannot hear until we use playback systems having very low levels of crosstalk. Converting one’s system to Ambiophonics will provide the opportunity to listen to old friends with new ears."

 

[f1eng]

I stiil find that the analog version will reproduce ambient information(if it is there) more completely it seems(reverberation,echo,ect.)

You may well be correct, but it could equally well be the ambience you are hearing is the extra reverb you get from an LP player picking up ambient airborne and structure borne vibration and adding that to the cartridge output, this definitely happens but I don't know to what extent it is audible. That was always the old thinking back when I was involved. Other analogue sources do not do this only record players do.
A record player is objectively the least good serious analogue source though we all enjoy them, perhaps this is why.

 

[f1eng]

So, does vinyl sound better using cartridges with more crosstalk?

In fact even the best cartridges have a huge amount of crosstalk so the difference between an outstanding cartridge and a modest one will be tiny compared to digital.
Digital can be >90dB. A modest cartridge may be 25dB mid band and almost mono at the frequency extremes whilst an exceptional one may be 30dB with maybe 20dB at 15kHz.
So I would imagine the differences between the crosstalk of cartridges is more to do with stable stereo imagery than pure SQ.

When I was involved in the business -25dB of crosstalk was considered ample.

 

[esldude]

You may well be correct, but it could equally well be the ambience you are hearing is the extra reverb you get from an LP player picking up ambient airborne and structure borne vibration and adding that to the cartridge output, this definitely happens but I don't know to what extent it is audible. That was always the old thinking back when I was involved. Other analogue sources do not do this only record players do.
A record player is objectively the least good serious analogue source though we all enjoy them, perhaps this is why.

I have checked this a few times. Depends on particulars of course. Ambient pickup tends to be -50 to -60 db from the signal. So might be audible.

 

[RogerD]

You may well be correct, but it could equally well be the ambience you are hearing is the extra reverb you get from an LP player picking up ambient airborne and structure borne vibration and adding that to the cartridge output, this definitely happens but I don't know to what extent it is audible. That was always the old thinking back when I was involved. Other analogue sources do not do this only record players do.
A record player is objectively the least good serious analogue source though we all enjoy them, perhaps this is why.

Well,I hear the difference between ADD and DDD digital....so my premise is that analog seems to better produce ambient information. Now I stated that hi res digital is better,but still analog seems to be a better format for this alone.

 

[puroagave]

Again, I think you are working with some mythology here. Think back to the 1970s when CD-4 LPs were cut- they used a 50KHz carrier that was modulated in FM stereo for the additional 2 channels. After that, RCA developed a color video disk media that used a needle to track the signal- to do color you need 2MHz response. Almost any LP system has 30KHz bandwidth between record and playback and some, between record and playback exceed 40KHz. I don't know of any CD format that has got that sort of routine bandwidth yet. On top of that, LF bandwidth goes well below 20Hz. Today we recorded a direct-to-disk session (will be on Nero's Neptune, a Twin Cities local label); we were seeing information recorded in the grooves caused by a train passing the studio that was only about 8 Hz. I had no idea the mics could go that low... we don' t get this sort of bandwidth on the analog tape!

early decca recordings at kingsway hall are known for the infamous "kingsway subway" that would intrude into the mix. It was at a very low level and freq but easliy discernible over a decent TT (evident on speakers corners LP reissues). in the day, Decca eng. would filter this at the disc cutting stage (typ of SXl 2000 series LPs). Hearing them now unfiltered is impressive when you consider it was 1950's technology at work, some of these are the best recordings i own in any format.

 

[RogerD]

There was a subway underneath the RCA recording studio in NYC and is clearly audible on Stakowski's Rhapsodies Tristan Und Isolde and that was done with David Sarser's Ampex 350's.

 

[Don Hills]

... Here in my home the highest quality analogue sound I ever hear is, and always has been, live BBC concert broadcasts. ...

You are presumably aware that the signal from the BBC control rooms to the transmitters is carried on a 10 bit (14 bit companded) 32KHz digital bearer?

 

[RogerD]

Thanks for posting this, Michael.

I had been curious about this phenomenon because one album stuck out like a sore thumb - Friday Night in San Francisco. Universally regarded as a fabulous album. However, when I got the SACD ripped, and played through a music server, it was unconvincing and sounded pretty bad. The guitars were left channel/right channel with almost no bleed. May be it's the crosstalk on vinyl playback that makes it sound great.

i must have missed this earlier,but I just came across this and I happened to address this in my system thread a while ago.

" I was listening to "A night in San Francisco" with Al Demiola,John Mclaughlin and Paco de Lucia last night and the whirlwind they created with the 3 guitars was reminiscent of listening to a quadraphonic recording. The space was completely holographic including the audience."
http://www.whatsbestforum.com/showthread.php?1769-My-2-channel-experiment/page5

Now since I use a crosstalk cancellation circuit + time domain correction among other methods....well this whole thing, adding crosstalk makes no sense to me. I think adding crosstalk to the digital signal might actually have the opposite effect in a very subtle way.

p.s. I used the Mastersound Gold CD

 

[f1eng]

You are presumably aware that the signal from the BBC control rooms to the transmitters is carried on a 10 bit (14 bit companded) 32KHz digital bearer?

Yes, I am.
That is why I know that the non-technical speculation that both the sampling frequency and bit depth of CD are the reason some people don't like it must be false.
BBC engineers were, IMHO, the best in the business and they did not go for the 24/32 transfer spec until it was demonstrable better than the analogue methods they used before.

 

[f1eng]

I have checked this a few times. Depends on particulars of course. Ambient pickup tends to be -50 to -60 db from the signal. So might be audible.

It was my job to check this sort of thing in the 70s.
50 to 60 dB below the music wouldn't be audible IME, but, depending on TT design and location being -20dB down in the bass was common, and whilst that may not be directly audible it is likely to give the impression of a bit more reverb.

 

[f1eng]

Well,I hear the difference between ADD and DDD digital....so my premise is that analog seems to better produce ambient information. Now I stated that hi res digital is better,but still analog seems to be a better format for this alone.

Well, there -will- be a reason for your aural impressions.
It may be that there is an as-yet-undiscovered-by-man explanation, or it may be a combination of the artifacts we have known about in the industry for 60 years. My bet is the latter.

 

[f1eng]

Back to the original OP, and the effect of crosstalk.
The difficulty of trying to over simplify where the difference between LPs and CDs lie is just that, a simple explanation is unlikely to be the whole story.
It is possible to model the crosstalk of a given cartridge and, probably these days, to run the algorithm in real time and listen to the effect. It may be possible to model the frequency response and distortion characteristics of any particular pickup cartridge and run that algorithm in real time and listen to that effect too.
It would be more difficult to model the time and frequency dependant vibration pickup of a turntable assembly, and such an algorithm may be impossible to run without latency. OTOH since this particular model will be unique to the turntable assembly and its location it will be unique for every TT in the world, hardly practical.
And so forth.
I have auditioned certain experiments giving non-intuitive results in the past and, frankly, real results are often not believed if they don't match peoples expectations.
A retired BBC sound engineer demonstrated some facts at the Scalford show a couple of years ago. He set up a pair of active Harbeth monitor 40s and demonstrated things like a 192/24 file, downsampled to 16/44 and then re-upsampled to 24/192. This meant that any DAC performance difference between 24/192 and 16/44 were not there but any information uniquely stored by 24/192 would have been removed.
He also demonstrated, using a 96/24 file of mine with which I am intimately aquainted, the effect of noise shaping, by converting it to 96/8 (yes 8-bit) on the fly with and without noise shaping.
I, and nobody else, could hear the difference between the 96/24 and 96/8 sound, I was even given the PC so I could make the change myself, I still couldn't hear any difference, nor could anybody else in the room. It was obvious when noise shaping was switched off, because the background noise increased.
I am of a scientific frame of mind and have done a lot of recording over the last 50 years so these revealations were good food for thought for me.
Some other listeners got quite angry and abusive, accusing the engineer of trying to trick them.

The fact is, most of us older enthusiasts have hundreds of LPs, and turntables we (presumably) like, I have 4 with different sound signatures.
Why not just enjoy them for what they are and not try to model them into a digital system?

Those who prefer LPs to CDs and vice versa are unlikely to change their POV. Discussions over why the differences are there always generate more heat than light on forums

 

[Uli]

So is Uli actually using crosstalk cancellation and is crosstalk cancellation occuring somewhere in the analog chain,that doesn't occur in the digital domain?

No,
I'm talking about the opposite.

Maybe we need to distiguish between 2 types of crosstalk at least:
1. crosstalk in analog circuits between channels
2. crosstalk from hearing the sound of two (or more) speakers with each ear

For 1) we have learnt for long time that we should avoid it.
For 2) we have different approaches to solve the problem, e.g. RACE and BACCHamongst others

I'm talking now about 1) The digital world does not know about crosstalk. Maybe we get it at the end when it comes to DA conversion and analog amplification. IMO this is a possible reason why the digital playback sounds digital and a perfect playback (free of crosstalk) worsens the result.
So it seems that a bit of frequency dependent crosstalk helps and it is recognized as comfortable, less nasty and more relaxing. IMO a possible reason is that the frequency dependent broadening of stereo playback gets reduced. A better localization relieves the brain.

So I'm talking about adding crosstalk which is the opposite of cancelling crosstalk
- Uli

 

[Phelonious Ponk]

Back to the original OP, and the effect of crosstalk.
The difficulty of trying to over simplify where the difference between LPs and CDs lie is just that, a simple explanation is unlikely to be the whole story.
It is possible to model the crosstalk of a given cartridge and, probably these days, to run the algorithm in real time and listen to the effect. It may be possible to model the frequency response and distortion characteristics of any particular pickup cartridge and run that algorithm in real time and listen to that effect too.
It would be more difficult to model the time and frequency dependant vibration pickup of a turntable assembly, and such an algorithm may be impossible to run without latency. OTOH since this particular model will be unique to the turntable assembly and its location it will be unique for every TT in the world, hardly practical.
And so forth.
I have auditioned certain experiments giving non-intuitive results in the past and, frankly, real results are often not believed if they don't match peoples expectations.
A retired BBC sound engineer demonstrated some facts at the Scalford show a couple of years ago. He set up a pair of active Harbeth monitor 40s and demonstrated things like a 192/24 file, downsampled to 16/44 and then re-upsampled to 24/192. This meant that any DAC performance difference between 24/192 and 16/44 were not there but any information uniquely stored by 24/192 would have been removed.
He also demonstrated, using a 96/24 file of mine with which I am intimately aquainted, the effect of noise shaping, by converting it to 96/8 (yes 8-bit) on the fly with and without noise shaping.
I, and nobody else, could hear the difference between the 96/24 and 96/8 sound, I was even given the PC so I could make the change myself, I still couldn't hear any difference, nor could anybody else in the room. It was obvious when noise shaping was switched off, because the background noise increased.
I am of a scientific frame of mind and have done a lot of recording over the last 50 years so these revealations were good food for thought for me.
Some other listeners got quite angry and abusive, accusing the engineer of trying to trick them.

The fact is, most of us older enthusiasts have hundreds of LPs, and turntables we (presumably) like, I have 4 with different sound signatures.
Why not just enjoy them for what they are and not try to model them into a digital system?

Those who prefer LPs to CDs and vice versa are unlikely to change their POV. Discussions over why the differences are there always generate more heat than light on forums

Bold 1: No. Really?

Bold 2: Had you read through the incredible, circular length of the most annoying threads on the board, you'd know that this can only be due to the inadequacies of the system, the switching, the testing methodology, or your hearing and the hearing of every one else who fails to confirm the expectations of the crowd. Or, if all else fails it will become obvious that differences indistinguishable through rapid switching between blind sources would become clearly audible in long-term sighted review.

Bold 3: Ah...proof that your mind has been clouded by all this science stuff. No one is trying to model their turntables into digital. That would be an abomination. They are trying to imagine a world in which their preference is objectively superior to that which is measurably superior by nearly every objective metric.

Welcome!

Tim

 

[JackD201]

Wake up on the wrong side of the bed Tim?

 

[jkeny]

I, for one, appreciate Uli's approach - he is trying to get at the psychoacoustic winning formula for better sound. This, to me, should be the quest that the audio industry is now engaged in after it has reached this level of maturity. Is it not time to reflect on the lessons of the past & what makes good sound, try to distill the psychoacoustic essence from this & apply it to our modern reproduction systems? This seems to me a more sensible approach than another Analogue Vs Digital debate?

I believe that there is a lot of learning still to be done (or maybe that's just me?) - pity there aren't more threads like this. I find the splash speaker/cube8 thread equally interesting

 

[Atmasphere]

So compression is/was used due to laziness, economics &/or bad technique - I can believe that. But I never heard that small amount of compression would perceptually increase the dynamic range. Have you experience of this?

Yes, and it doesn't

Firstly there is the limitations of the manufacturing process. The best engineers always pushed the limits here but plenty took it easy and did not! Firstly, in order to have a continuous groove the bass must be monoed.

I could not let this pass. Its patently untrue. What is true has to do with out-of-phase information, something that rarely if ever shows up with a live recording. But if it does, and is so bad that you can't get around it by changing the level slightly or cutting a deeper groove, the processor that takes care of it will only make the bass mono for a few milliseconds at most. I've often thought we would need such a thing (which BTW is otherwise a passive device in the signal chain) but so far have yet to see a recording where this is required. So every stereo LP we have done also has full-stereo bass.

Low levels of bass can just about be cut on a record but with the risk of wavering stereo imagery (at what point does bass really become non directional?) it may as well all be monoed. Secondly no cutters can record high frequencies at maximum level. If the master is analogue that is OK since neither can tape recorders, but otherwise some sort of limiting is necessary.

Analog tape can do full output at any frequency within the passband. LP you do have to watch it, but it is not as fragile as suggested. But there will never be a full output signal at high frequencies recorded in any media except for testing- most tweeters don't handle more than a few watts for the same reason...

My belief is that the reason many modern recordings sound bright, harsh, unpleasant, what-have-you is down to microphone choice and positioning, not the method of recording/distribution.
Back in the day we had 2 large sensitive microphones positioned almost as far from the performers as the audience would be at a concert. The sound balance was largely achieved by moving microphones and performers. The sensitive microphones had large capsules and rolled off pretty early, so didn't sound harsh. They weren't shoved right against the instrument either.
Nowadays multiple super high bandwidth microphones are shoved right against the performers or instruments to be mixed up later. What have we lost? A natural treble roll-off. Phase coherence. A natural acoustic. What have we we gained? A totally un-natural perspective. Un-naturally high levels at high frequencies. A mish-mash of mixed together manipulated phase inconsistent mess. Harshness.

Just IMHO.

^^ one which I share.

Whether you need to compress to get onto LP depends on the dynamic range of the music you are recording. Small ensemble acoustic usually does not. Rock music doesn't either but large scale classical music has a higher dynamic range than any domestic hifi is capable of, including the LP, so compression is necessary though it doesn't need to be excessive. So yes, unless you are making LPs of symphonic music compression won't be necessary, just care to get the levels in the window, which you are obviously getting right.

CD can get away with less compression than LP without sound quality problems, so is potentially better for high quality classical recordings. High compression on recent CDs is because that is what people want, particularly for cars and earbuds in public not because it sounds better or is needed, CD has more dynamic range potential than LP, it is not a fault of the medium that some [EDIT:] people don't use it.

You certainly can record 30kHz on LP but only at limited maximum level, and it wears off the record PDQ. OTOH many of the finest sounding pickups can not play it back and those that can are usually into double figures of distortion at those freqencies. IMHO one of the things which I like best about LPs is the absence of HF sting. A bit like the old definition of a gentleman being somebody who knows how to play the bagpipes but doesn't, a good recording engineer is somebody who knows how to record extreme HF but doesn't - just a personal view.

Interesting that you recorded 8Hz on your direct to disc recording, fine microphones you have there!, though it could be at least partly structure borne pickup at that frequency. You seem to be unaware, however, how a seismic vibration pickup such as a cartridge works. No properly matched cartridge/arm could accurately play 8Hz.
FWIW a seismic pickup produces spurious/resonant output at frequencies below around 2x the natural frequency. In the case of a record player that is the Fn of the arm/cartridge mass on the cartridge compliance. Since in a well matched pairing this will be 20-25Hz anything lower than that will be still influenced by transucer resonance. At 8Hz the output will probably being exaggerated by 5x and be all over the place phase-wise. That is why the RIAA standard specifies a high pass filter. Of course without this filter there will be more LF output but it is amp and speaker overloading garbage and sensibly removed.

FWIW the RIAA curve does not specify a high pass filter beyond that of the curve itself. There are such filters in use but they are not part of the RIAA curve.

Actually I am very aware of how cartridges playback and their interaction with the arm! All mastering engineers have to understand the limitations of the playback apparatus.... The mechanical resonance describes the lower limit of any LP playback system. Upon listening to the digital backup we found the 8Hz (or thereabouts) to be a foot stomp, with exactly 1 sine wave iteration. It was at low level, and since we were doing direct to disk there was not a lot to be done about it.

In practice I've never had to compress any classical recording I have done. If you can put it on analog tape, you can put it into the LP too, as it has wider dynamic range than analog tape does, with a lower noise floor.

I am of the opinion that the highs of the LP are preferable as there is less distortion of the types that are annoying to the human ear/brain system, and otherwise less phase shift with more bandwidth.

To put this back on track, I am wondering if the phasing issue would have been better done by applying Ambisonic techniques rather than trying to mimic the behavior of a certain cartridge in a certain arm (as they all tend to be a bit different- the better the arm tracks the cartridge, the less crosstalk there is).