Vinyl Heads, Take Note

[krabapple]

Yea LP's are not great with square waves but 44.1 digital is so bandwidth limited it does not do very well with higher frequency square waves either. My point is while I do understand how square waves can be very useful to quickly troubleshoot issues with electronics using them to determine how something is going to sound playing back actual music is not so clear cut.

Square wave comparison arguments have an element of bogusness in them. The components of 'high frequency square waves' -- higher order harmonics -- that makes them square, are not heard by human ears.

What's important is how well the part that humans CAN hear, is reproduced distortion free. Put another way, you can fudge a lot of 'squareness' and humans won't hear a difference.

 

[Jim Shaw]

Square wave comparison arguments have an element of bogusness in them. The components of 'high frequency square waves' -- higher order harmonics -- that makes them square, are not heard by human ears.

What's important is how well the part that humans CAN hear, is reproduced distortion free. Put another way, you can fudge a lot of 'squareness' and humans won't hear a difference.

Trying to reproduce square waves on audio equipment is actually an exercise for measurement. Certainly not for a listening test. Many readers here, and more elsewhere, could be confused by this.

Square wave, step function, and impulse response are tests primarily conducted to try to characterize the transfer function of a device, rise-time, ringing, power transfer, and so on. Audiophiles are unlikely to have the background to understand this, determine its usefulness, or even decide if it has usefulness. But it's fun to argue about, I notice.

If you don't know what a transfer function is, just ignore this stuff. It carries little meaning without the mathematics to understand it. If you DO know what a transfer function is and what it means, well then you know its usefulness (or not) in systems engineering. And it is just one of many factors in system design.

 

[Cbdb2]

Squares and impulses can also show you amplifiers on the edge of stability.

 

[BogdanR]

Your confusing the artists medium and its delivery. A painting can be seen from a TV or a printed page.

That’s the wrong analogy to bring forth.

 

[EarlessOldMan]

Square wave comparison arguments have an element of bogusness in them. The components of 'high frequency square waves' -- higher order harmonics -- that makes them square, are not heard by human ears.

What's important is how well the part that humans CAN hear, is reproduced distortion free. Put another way, you can fudge a lot of 'squareness' and humans won't hear a difference.

I'm 65. I grew up shooting guns, running power saws, mowing lawns with power mowers, and other such things without hearing protection. I have vicious tinnitus. I ain't fooling' myself at all: I know my hearing's shot, so I ain't gonna claim I can hear a danged thing particularly well . . .

 

[Dgob]

I'm 65. I grew up shooting guns, running power saws, mowing lawns with power mowers, and other such things without hearing protection. I have vicious tinnitus. I ain't fooling' myself at all: I know my hearing's shot, so I ain't gonna claim I can hear a danged thing particularly well . . .

 

[atmasphere]

The third is mixed with bass in the center and some compression to handle vinyl's narrower dynamic range and limited ability to handle stereo low frequencies, narrow stylus excursions, and acceptable groove spacing.

Actually its quite common when mastering for LP to use a digital source file that lacks compression. This allows the engineer to cut a better sounding LP. Of course the CD has wider range in theory. But in practice if the LP mastering engineer has been doing his homework the LP will actually have the wider dynamic range on this account. Also, bass does not have to be mono unless out of phase bass is in the recording to be produced. If that is the case a processor can be used that monos the bass only when the out of phase bass is present, but IME if you just spend a bit more time on the project you can sort out how to cut the out of phase bass without any trouble. One way to do that might be to cut the modulation overall by a dB or two since a 3dB cut will cut the modulation in half. It is amplifier power we're talking about after all. I've also increased the groove depth to deal with this problem. As a result I've never had to resort to the processor; its merely a time saver, not a requirement.

 

[Dgob]

Actually its quite common when mastering for LP to use a digital source file that lacks compression. This allows the engineer to cut a better sounding LP. Of course the CD has wider range in theory. But in practice if the LP mastering engineer has been doing his homework the LP will actually have the wider dynamic range on this account. Also, bass does not have to be mono unless out of phase bass is in the recording to be produced. If that is the case a processor can be used that monos the bass only when the out of phase bass is present, but IME if you just spend a bit more time on the project you can sort out how to cut the out of phase bass without any trouble. One way to do that might be to cut the modulation overall by a dB or two since a 3dB cut will cut the modulation in half. It is amplifier power we're talking about after all. I've also increased the groove depth to deal with this problem. As a result I've never had to resort to the processor; its merely a time saver, not a requirement.

I can only say that, if your overall system allows, well mastered (and cared for) vinyl is simply amazing. For example, with a cartridge such as the DH3 from Northwest Analogue or the MCX4 from Acoustic Signature (and appropriately accurate supporting components) the either/or thinking around music reproduction and experience just disappears.

 

[Jim Shaw]

Actually its quite common when mastering for LP to use a digital source file that lacks compression. This allows the engineer to cut a better sounding LP. Of course the CD has wider range in theory. But in practice if the LP mastering engineer has been doing his homework the LP will actually have the wider dynamic range on this account. Also, bass does not have to be mono unless out of phase bass is in the recording to be produced. If that is the case a processor can be used that monos the bass only when the out of phase bass is present, but IME if you just spend a bit more time on the project you can sort out how to cut the out of phase bass without any trouble. One way to do that might be to cut the modulation overall by a dB or two since a 3dB cut will cut the modulation in half. It is amplifier power we're talking about after all. I've also increased the groove depth to deal with this problem. As a result I've never had to resort to the processor; its merely a time saver, not a requirement.

I agree, for modern recordings.

I have long attributed 'vinyl sound' largely to the character of the master cutting head. I cannot determine how many (or few) actual such cutting head makes and models are mostly used in actual practice, but the Westrex 3D does have -- by virtue of its mechanical elements -- a sound signature. Especially a couple of resonances (at ~7 kHz and 12 kHz as I recall). I make the loose point that much of vinyl is cut in a process that is somewhat like playing every recording through the same speaker model. You get similar bandwidth, distortion, and resonant frequencies on everything (at least cut with the Westrex 3D).

I know that many steps are taken to flatten the 'character' of cutters. But they are all, to my knowledge, more the same than different. They introduce the mechanical kinetics of a machine which pure digital does not.

And so does the playback cartridge-stylus offer a 'character' that even untrained ears can discern across various makes and models.

-Just one man's view.

 

[atmasphere]

I have long attributed 'vinyl sound' largely to the character of the master cutting head. I cannot determine how many (or few) actual such cutting head makes and models are mostly used in actual practice, but the Westrex 3D does have -- by virtue of its mechanical elements -- a sound signature. Especially a couple of resonances (at ~7 kHz and 12 kHz as I recall). I make the loose point that much of vinyl is cut in a process that is somewhat like playing every recording through the same speaker model. You get similar bandwidth, distortion, and resonant frequencies on everything (at least cut with the Westrex 3D).

It is true that there is a resonance in the cutter, as there is in any cutter.

What you are probably not taking into account is there is a feedback module that imposes 30dB of feedback at all audio frequencies (in the case of the Westerex 1700 electronics; this value is similar in any cutter system used) that handles resonance quite handily (the cutter has a feedback winding for this purpose, which is also used to allow the engineer to monitor the cut in real time). The electronics are also matched to the cutter to equalize out variance; the individual characteristic of the cutter is EQ'ed in the pre-emphasis module.

It would be as if the loudspeaker in your emphasis added sentence were not only EQ'ed to flat but is also included in a 30dB feedback loop (independent of the feedback in the amplifier, which also controls resonance in the load, being a voltage source)! The result is the cutter system is extremely neutral with the overall distortion very low (most of the 'distortion of the LP' actually arises in playback, not record, which means the key to neutrality of this media is in the hands of the user, much more so that with digital (and IMO, is thus its primary weakness) since the cutter amps never operate at more than even 10% of full power (unless in the act of a teachable situation where the cutter is being blown up by a stupid mistake ).

Quite literally its the only recording method I've seen that can't be overloaded, unlike analog tape or any digital system. The thing that the engineer has to watch is to make sure that the cutter is cutting a groove that is trackable by the cartridge/arm combo, since playback is the limitation in the system, while not overcutting into a prior part of the cut.

 

[Jim Shaw]

It is true that there is a resonance in the cutter, as there is in any cutter.

What you are probably not taking into account is there is a feedback module that imposes 30dB of feedback at all audio frequencies (in the case of the Westerex 1700 electronics; this value is similar in any cutter system used) that handles resonance quite handily (the cutter has a feedback winding for this purpose, which is also used to allow the engineer to monitor the cut in real time). The electronics are also matched to the cutter to equalize out variance; the individual characteristic of the cutter is EQ'ed in the pre-emphasis module.

It would be as if the loudspeaker in your emphasis added sentence were not only EQ'ed to flat but is also included in a 30dB feedback loop (independent of the feedback in the amplifier, which also controls resonance in the load, being a voltage source)! The result is the cutter system is extremely neutral with the overall distortion very low (most of the 'distortion of the LP' actually arises in playback, not record, which means the key to neutrality of this media is in the hands of the user, much more so that with digital (and IMO, is thus its primary weakness) since the cutter amps never operate at more than even 10% of full power (unless in the act of a teachable situation where the cutter is being blown up by a stupid mistake ).

Quite literally its the only recording method I've seen that can't be overloaded, unlike analog tape or any digital system. The thing that the engineer has to watch is to make sure that the cutter is cutting a groove that is trackable by the cartridge/arm combo, since playback is the limitation in the system, while not overcutting into a prior part of the cut.

All true. But I add another consideration: Feedback, when provided by a pickup coil at the cutting head, can only react so quickly. The mechanism must move first before feedback is generated. Thus, it irons out most resonance issues, it is less than perfect at transients. It has to make the error before it starts to correct the error. So the cutting head system still has a 'sound' based on its mechanics. Those in the business just have to get accustomed to it because 'it is what it is.' And we do.

When [physics] gives you lemons, make lemonade.

But again, as you point out, comparing an electromechanical system (which has mass, inertia, momentum, stored energy, almost but not linear restoring forces, and so on) makes comparison with massless, inertialess, momentumless, stored energyless, and no restoring force, et al, a pitched battle.

Enter the human hearing, which is typically more pleased with even harmonics than odd harmonics, and the battle turns. Nearly linear mechanical systems are much more likely to produce even harmonics than odd ones. Many listeners even seem addicted to this.

I suppose we could go on here indefinitely describing the difficulties of electromagnetic audio recording. And it serves some public good if folks understand some of the issues. I suffice it to say that the whole process has been developed by very smart folks, with much motivation, to a fine system that pleases a fairly large portion of the buying public. And when asked the time, we really shouldn't be compelled to treat the subject of how to build a clock.

It's only when someone asks why an Atomichron is more accurate than their mantel Seth Thomas that we do go on...

 

[atmasphere]

Feedback, when provided by a pickup coil at the cutting head, can only react so quickly. The mechanism must move first before feedback is generated.

FWIW the cutter is pretty quick; having response to well past 40KHz. What you seem to be suggesting might mean that at low levels there could be a problem. But I don't think its any issue, since there is also feedback in the amp driving the cutter, in much the same way that feedback allows an amplifier to respond to resonance in a loudspeaker. So we have three methods of dealing with the cutter's characteristic, whereas in a home loudspeaker we typically only have one, since the model falls apart since a loudspeaker is dealing with a room while a cutter head isn't (DSP room correction might be blowing a hole in my argument since its dealing with room issues and certainly speaker issues too, delivering feedback and EQ at the same time).

Modern self-oscillating class D amplifiers tend to have a lot more feedback than conventional A or AB amp designs; before selling off my lathe I had considered installing class D modules to replace the cutter amps, since class D amps come out of the box nicely bandwidth limited and immune to stability issues. Westerex was pretty advanced in their day but frankly the 1700 amps were a bit on the sketchy side (the design is from the late 1960s....); I cringed every time I powered them up. There is obvious room for improvement!

 

[beagleman]

Typically 15kHz.

Quad records were cut at half-speed. HF content on test records is is low amplitude and very short duration and/or some were cut at half-speed or slower as well, like the 45-50kHz sweeps.

Great reply and the truth.

A lot of the built in limitations of vinyl can be gotten around in the manner you describe.
Musical content that goes on for several minutes, can not press high level high frequencies.

Also the RIAA curve boosts the highs to a great degree so that limits highs also. Because of the great amount of boost, which is reduced during playback, they cutter head can overheat easier.

Also only the outer grooves can take higher level upper frequencies. The inner portion is moving at a different relative speed and diameter.

 

[atmasphere]

Musical content that goes on for several minutes, can not press high level high frequencies.

Also the RIAA curve boosts the highs to a great degree so that limits highs also. Because of the great amount of boost, which is reduced during playback, they cutter head can overheat easier.

Also only the outer grooves can take higher level upper frequencies. The inner portion is moving at a different relative speed and diameter.

Even if the lathe speed is 33 1/3rd RPM the cutter can sustain high frequencies indefinitely since they are never cut at full modulation.

The second sentence contradicts itself rather obviously- I'm sure this isn't what you meant to say. Having blown up a few cutter heads I can tell you that they don't overheat from musical information, they overheat and fail due to stupid mistakes...!

The high frequency limit in the inner grooves was an old problem of early stereo cartridges from the 1950s and 60s and isn't a problem at all with any modern cartridge; IOW this is a bit of a myth. I was easily able to cut test tones at 25KHz and have them play back even in the lead out grooves. My cutter system was a Scully lathe with Westerex 3d Cutter head and Westerex 1700 electronics, stock but refurbished. I cut even higher tones elsewhere further from the center spindle.

I had a lot of the same misconceptions as you; they died one by one as I gained more experience with the cutter system.

 

[beagleman]

Even if the lathe speed is 33 1/3rd RPM the cutter can sustain high frequencies indefinitely since they are never cut at full modulation.

The second sentence contradicts itself rather obviously- I'm sure this isn't what you meant to say. Having blown up a few cutter heads I can tell you that they don't overheat from musical information, they overheat and fail due to stupid mistakes...!

The high frequency limit in the inner grooves ws an old problem of early stereo cartridges from the 1950s and 60s and isn't a problem at all with any modern cartridgea; IOW this is a bit of a myth. I was easily able to cut test tones at 25KHz and have them play back even in the lead out grooves. My cutter system was a Scully lathe with Westerex 3d Cutter head and Westerex 1700 electronics, stock but refurbished. I cut even higher tones elsewhere further from the center spindle.

I had a lot of the same misconceptions as you; they died one by one as I gained more experience with the cutter system.

I am not certain you want to understand what I am saying. You seem intent on claiming everything is nearly perfect with vinyl,.



This is another well known issue, and you claim to have actual experience cutting vinyl records, and seem unaware. I am not sure what you are trying to prove or what your point is honestly.
'
"The end-of-side distortion problem is caused by a combination of factors, but it's essentially a fundamental design flaw of both the medium itself and the standard replay mechanisms, and it can never be completely eradicated.

The basic issue is the linear speed of the groove modulation — the speed of the vinyl passing under the stylus — which becomes much slower for the inner cuts compared with the outer grooves. This means that the recorded wavelengths are correspondingly much shorter and the slope angles are much greater for the inner grooves compared with the outer ones, so the pickup stylus has a much harder time trying to follow the groove.

The problem is worse with higher recorded volumes and greater amounts of high-frequency energy, so cutting engineers tend to prefer placing quieter songs, with moderate bass and lower HF energy towards the centre of the disc — or just restrict the playing time so that the grooves don't have to get too close to the centre."

so you actually cut records, and are not aware that inner grooves sound different and have limitations compared to the outer grooves?
Calling it a myth and based only on cartridges..............uhm>???

 

[egellings]

Square wave comparison arguments have an element of bogusness in them. The components of 'high frequency square waves' -- higher order harmonics -- that makes them square, are not heard by human ears.

What's important is how well the part that humans CAN hear, is reproduced distortion free. Put another way, you can fudge a lot of 'squareness' and humans won't hear a difference.

I think that music signals don't come close to having rise & fall times comparable to those in square wave edges, so having the ability to reproduce a square wave would get you little more than bragging rights.

 

[atmasphere]

I am not certain you want to understand what I am saying. You seem intent on claiming everything is nearly perfect with vinyl,.



This is another well known issue, and you claim to have actual experience cutting vinyl records, and seem unaware. I am not sure what you are trying to prove or what your point is honestly.
'
"The end-of-side distortion problem is caused by a combination of factors, but it's essentially a fundamental design flaw of both the medium itself and the standard replay mechanisms, and it can never be completely eradicated.

The basic issue is the linear speed of the groove modulation — the speed of the vinyl passing under the stylus — which becomes much slower for the inner cuts compared with the outer grooves. This means that the recorded wavelengths are correspondingly much shorter and the slope angles are much greater for the inner grooves compared with the outer ones, so the pickup stylus has a much harder time trying to follow the groove.

The problem is worse with higher recorded volumes and greater amounts of high-frequency energy, so cutting engineers tend to prefer placing quieter songs, with moderate bass and lower HF energy towards the centre of the disc — or just restrict the playing time so that the grooves don't have to get too close to the centre."

so you actually cut records, and are not aware that inner grooves sound different and have limitations compared to the outer grooves?
Calling it a myth and based only on cartridges..............uhm>???

I don't want to talk past you. Nor is my intent to speak about how perfect vinyl is- as a mastering engineer I'm well aware of its shortcomings. I'm more interested in setting the record straight (if you see what I did there ) about which stories out there are real and which ones aren't. This happens to be one that was real, but isn't any longer due to advances on the playback side that have occurred in the last 50 years.

I understand entirely how the media is moving slower due to the reduced radius near the center! My point was that while that is true, it does not affect the audio passband with modern styli because the cutter can easily cut modulation at 20kHz no worries. It most definitely affects it with the older 1960s-and-before cartridges about which scholarly papers that still get linked today are written.

The main limitation of the LP isn't on the record side- its playback. If the cartridge is competent and in an arm that can track it properly you won't have any trouble getting bandwidth in the inner grooves to well past 25kHz. But! - if the cartridge is a bit of excrement, if it or a perfectly good cartridge is poorly set up in any kind of arm, it will have problems! The point here is that the abilities of the media is based almost entirely on the user, which is a terrible place to put such a thing! The media is fragile and has to be treated with care- everything about it is tricky, starting right on the mastering side (how well the cutter head is set up, which must be done every 10 hours of use since that is how long a stylus is good before it gets too noisy), how the engineer dealt with tricky stuff like out of phase bass and so on. But at least such people have some technical know-how and have ways of dealing with it. Most consumers simply don't! That is the main reason digital is better, since a lot of the time even if you have separates its plug and play with good results- no tweaking.

 

[Robin L]

I understand entirely how the media is moving slower due to the reduced radius near the center! My point was that while that is true, it does not affect the audio passband with modern styli because the cutter can easily cut modulation at 20kHz no worries. It most definitely affects it with the older 1960s-and-before cartridges about which scholarly papers that still get linked today are written.

No need to go back as far as the sixties for styli that eat records. Plenty of badly aligned styluses from as late as right now, with one of the most common being an Audio Technica conical stylus still in production and tracking at three grams. Not to mention Shure's last gasp with the 97xe, many with their elliptical styli out of alignment right on the cantilever. These are common cartridges, usually not properly set up and found on common turntables. You are speaking about the best realizations of playback that only obtains with very few people playing LPs, the small percentage of folks using what is properly considered the "high end" of LP reproduction. In the real world, most records are trashed soon after they are purchased.

 

[atmasphere]

Yup!!

 

[OldHvyMec]

so you actually cut records, and are not aware that inner grooves sound different and have limitations compared to the outer grooves?
Calling it a myth and based only on cartridges..............uhm>???

Cut records and built quite a few other goodies too. If you pay attention you will also understand he provides a wonderful source of
information on the subjects he has personally worked with and "TESTED". I can't recall a single time Mr. Ralph hasn't helped people out if he
was asked a question. I could always follow what he was saying. He has a way of explaining things that disarm the complexity without detracting
from the meaning. I'm sure you see the gentleman he is being. That is something he always is, and informed professional and a gentleman to boot.

I have used and owned a few of his Valve amps. Very high quality craftsmanship inside and out.. Like a piece of art inside, I'm pretty picky.

I will say this about vinyl, it was my favorite medium and is still used in my home 50% of the time. The truth about vinyl is, you either like it or not.
Like anything there are degrees of OCD.

I've seen people collect 1-? copies of an LP before settling on one or two. I admit vinyl is a one of the biggest investment a person can make.
I will also share, 20 good LPs, a select TT and Phono stage will do a wonderful job too, without breaking the bank.

Me and the neighbor did a garage sale find around the corner for 500.00. It took a dolly to get it all home. A crate of LP, 2 Thoren TT, EAR, and one
SS phono stage. There was a new Ortofon blue and black in the case. We went back to give her some more money for the find in the box. She insisted
we take 2 more boxes of LPs and a crate of tonearms. She refused to take any more money. Her late spouse and their kids were there throwing everything
away or selling it.

One persons "Stuff". She said she would have tossed it all it the bin if we wouldn't have taken it. I've picked up at least 15 good TT for under 100.00,
1/2 of those were take the pile. I quit looking, I ran out of room.

Regards