Why no turntables?

[Bland_username42069]

I can’t see the point in measuring turntables - direct drive has the best wow/flutter and rumble and technics is the best of the new direct drives so we know the standard.

 

[DVDdoug]

CD has better bass and sometimes more detail

CDs are dead-flat from DC (0Hz) to about 20kHz. The high end is absolutely limited to 22,050Hz (half the sample rate) and there is filtering so it doesn't that high but it's usually pretty-flat to 20kHz. Some CD players (most?) filter-out the DC and very low frequencies. It isn't "sound" and it can sometimes cause problems.

Phono cartridges and phono preamps aren't as perfect. There are variations over the frequency range. There also may be variations on the record-cutting side. And the the deep bass is usually attenuated intentionally to help with tracking. They CAN go ultrasonic (higher than CD) but that's not "sound" either.

 

[Palmer]

How do you measure the lateral force it generates?

Easy, two tractor beams, and measure the difference.

 

[watchnerd]

I can’t see the point in measuring turntables - direct drive has the best wow/flutter and rumble and technics is the best of the new direct drives so we know the standard.

If you don't want a Technics, or it's out of budget, you might want to know how an alternative measures.

I have a Michell Gyro SE because I prefer the way it looks and the ease of adding a 2nd arm, or changing arms.

I like to measure it to keep it running as well as it can be.

 

[MaxwellsEq]

CD's are dead flat, but that is only the data, the electronics and in particular the analogue outputs are not, and they have distortion, also CD data produces high levels of (Audio) hi frequency distortion ( in the D-A stage) which in early players was around 11% at 8kHz and got worse at 10kHz, so it is the whole play back system that counts not just the 'data' medium.

I don't think anything you've written is correct.

 

[watchnerd]

CD's are dead flat, but that is only the data, the electronics and in particular the analogue outputs are not, and they have distortion, also CD data produces high levels of (Audio) hi frequency distortion ( in the D-A stage) which in early players was around 11% at 8kHz and got worse at 10kHz, so it is the whole play back system that counts not just the 'data' medium.

What is an example of a CD player that did this?

Correct, Phono cartridges and phono amps are not perfect but high-end ones are pretty good 30 dB Channel separation 90dB dynamic range 15Hz to 40kHz. The bass is attenuated according to the RIAA curve specifically so the reverse curve can be accurately generated by the phono stage - modern good ones are within 0.2 dB 15Hz to 20kHz.

What is an example of a phono stage that has 90 dB dynamic range?

High 70s / low 80s for MM is pretty good.

Also, the dynamic range of LP itself isn't 90 dB / 15 bits, so it's pretty moot.

 

[JeffS7444]

I can’t see the point in measuring turntables - direct drive has the best wow/flutter and rumble and technics is the best of the new direct drives so we know the standard.

And yet, their current offerings range in price from less than 1K USD to more than 10K despite very similar W+F specs. I wonder if I'd be able to discern differences between the most and least expensive in a DBT.

 

[Robin L]

What is an example of a CD player that did this?



What is an example of a phono stage that has 90 dB dynamic range?

High 70s / low 80s for MM is pretty good.

Also, the dynamic range of LP itself isn't 90 dB / 15 bits, so it's pretty moot.

The dynamic range of an LP probably isn't even 80 db. And turntables reach for 80 db as a noise floor, probably more like 75db. Again, the real point is finding out the point that people would find the deficiencies acceptable. The "high-end" Technics SL-1000R has a (weighted) noise floor of -74.9/-74.1 db and other noise noise/hum of -60 db. My cheap Topping E30 DAC has a SINAD of 112. Really no contest.

 

[JP]

Direct drive doesn't wow because it uses high speed correction, they jitter instead like a CD.

False.

 

[MRC01]

How do you measure the lateral force it generates?

Easy, two tractor beams, and measure the difference.

A calibrated spring aligned horizontally and connected to a vertical push-plate, like a tiny version of a bathroom scale on its side?
A string with a hook around the tonearm, going around a pulley with a weight hanging from the other end?
A Wally-Skater? I never heard of this before, but apparently it's a thing and Stereophile reviewed it (FWIW).

 

[andy_s]

What is an example of a CD player that did this?



What is an example of a phono stage that has 90 dB dynamic range?

High 70s / low 80s for MM is pretty good.

Also, the dynamic range of LP itself isn't 90 dB / 15 bits, so it's pretty moot.

"the Spartan 15 Mk 2 is said to deliver a digital-audio level dynamic range of over 110dB"

Spartan 15 Mk 2 Phono Preamp by Michael Fidler and Classic Audio

Michael Fidler is a bonafide classic audio maestro, and he knows how to build phono preamps about as good as anybody can. To that end, the latest phono preamp offering from Michael Fidler and Classic Audio, the Spartan 15 Mk 2, is said to have evolved the standards set with company’s prior...

www.analogplanet.com

 

[andy_s]

A calibrated spring aligned horizontally and connected to a vertical push-plate, like a tiny version of a bathroom scale on its side?
A string with a hook around the tonearm, going around a pulley with a weight hanging from the other end?
A Wally-Skater? I never heard of this before, but apparently it's a thing and Stereophile reviewed it (FWIW).

Just came in to mention the WallySkater, looks quite fiddly but was interesting to see how to 'measure' skate.

 

[GuidoK]

I know, that is my point. Different turntables & arms use different methods to apply anti-skate forces. Some of these methods (such as a suspended weight) apply a constant force, others (such as springs) apply a force that increases or decreases as the arm moves across the record. It may be useful to measure this.

Suspended weights don't apply a constant force. The weight pulls with a constant force on the string (or whatever), but the bar on which that string sits usually makes a rotational movement which results in a lever with different lengths as the tonearm moves across the record.
Pretty much no AS system applies a constant force, except maybe an electrodynamic one depending on the design.
That said does the AS force needs to be constant? The tracking error also changes across the record and though not much (compared to the offset angle) it still gives a slight variation.

But the bigger question here is: do they apply more or less the correct force?
My experience is (measuring with side force checkers) that the amount of force applied, according to the indicator on the dial or notches on a bar (with a weight) or whatever gives a bigger deviation to what is needed than the non linearity of the force applied over the range of the tonarm on the record.
Obviously the required AS force depends on the modulation of the groove, but that doesn't mean it can't be off so far that it's pretty much never right.
That said, obviously I haven't measured all tonearms in existence.

 

[GuidoK]

Just came in to mention the WallySkater, looks quite fiddly but was interesting to see how to 'measure' skate.

The wallyskater doesn't measure skate, it measures antiskate. That's a fundamental difference.

 

[MaxwellsEq]

Feel free to fact check any of the commentary

I did. You made a set of statements, each of which is false. What's more, your extraordinary claims were backed by no evidence.

Extraordinary claims require extraordinary evidence - Wikipedia

en.wikipedia.org

So I was entitled to invoke Hitchens's Razor

Hitchens's razor - Wikipedia

en.wikipedia.org

 

[Bob from Florida]

As I noted, I can characterize the speed and could do resonances. Seems like a lot of logistical work to produce two graphs. Are folks going to be happy with just that?

Thanks for doing reviews and thinking about measuring turntables!

Some information is better than none - the basics would be a good reference. While some folks will be satisfied, plenty of others will find something to complain about.

 

[Frank Dernie]

As I noted, I can characterize the speed and could do resonances. Seems like a lot of logistical work to produce two graphs. Are folks going to be happy with just that?

My advice would be not to bother since there are too many other variables affecting the output which you won't be able to consistently or universally measure. The speed apps on phones are probably accurate enough and the influence and magnitude of resonance in different parts not transferrable.

Back in the mid-1970s it was one of my jobs as a noise and vibration research engineer to measure turntables at Garrard, both our own prototypes and competitors models.
To get accurate rumble measurements we needed to put any TT on a 50ish kg concrete block suspended from a steel frame on carefully angled steel springs about 600 mm long which isolated the TT from the environment - if not many would be picking up the vibration of traffic passing the 4th floor lab at the other side of the car park.
Some decks were OK on their own, most weren't.
Nobody is going to have an installation like that at home...

Things I found make a difference to the cartridge output are legion, rarely if ever mentioned in this second wave of interest in LPs.
There is a tendency to use static reasoning to try to understand how a turntable assembly works as a transducer which is simply wrong and leads to ridiculous (IMO) conclusions.

I still have LPs but only play one if the next piece of music I wish to listen to is on an LP, which is not often
I still have 4 turntables:-
A Goldmund Reference with T3f arm and Ortofon A90 cartridge, which is probably the most accurate from the POV of isolation and even frequency response.
An EMT 938 with either a Stanton or Decca gold cartridge.
A B&O 8002
A Roksan Xerxes with Rega arm and Ortofon Jubilee cartridge.

I have no idea how good cheap turntables are today but my experience 50 years ago was considerable variability from sample to sample.

For the benefit of @WisEd I can reveal the original DD turntables we tested were excellent and after stripping to cost them my boss bought the Sony from the "scrap man" and I the Technics SP10 which was almost as good. I reassembled it and used it for some years.

 

[Bob from Florida]

My advice would be not to bother since there are too many other variables affecting the output which you won't be able to consistently or universally measure. The speed apps on phones are probably accurate enough and the influence and magnitude of resonance in different parts not transferrable.

Which phone apps are accurate? I have both versions of the RPM app on my iPhone and it measures consistently high on speed when compared to the Waxwing speed test. The Waxwing measures exactly 33.33 and 45.00 every time I check on the Technics 1300G. Phone is always high by a fraction of a percent. Waxwing is absolutely accurate because it counts the runout click of once per rotation.

 

[Frank Dernie]

Which phone apps are accurate? I have both versions of the RPM app on my iPhone and it measures consistently high on speed when compared to the Waxwing speed test. The Waxwing measures exactly 33.33 and 45.00 every time I check on the Technics 1300G. Phone is always high by a fraction of a percent. Waxwing is absolutely accurate because it counts the runout click of once per rotation.

accurate enough for me , I deleted the one I have because it showed my turntable speed was near enough.
Whilst the performance of a record player in terms of frequency response evenness, overload, signal to noise ratio and bass accuracy is demonstrably not all that good it is good enough for a lot of people I know to believe it is state of the art sound, when evaluated by ear.
Because of the generator linearity and stylus profile the cartridge output variability is a good way to (or was) to tune a system to taste.

 

[DSJR]

CD's are dead flat, but that is only the data, the electronics and in particular the analogue outputs are not, and they have distortion, also CD data produces high levels of (Audio) hi frequency distortion ( in the D-A stage) which in early players was around 11% at 8kHz and got worse at 10kHz, so it is the whole play back system that counts not just the 'data' medium.

Correct, Phono cartridges and phono amps are not perfect but high-end ones are pretty good 30 dB Channel separation 90dB dynamic range 15Hz to 40kHz. The bass is attenuated according to the RIAA curve specifically so the reverse curve can be accurately generated by the phono stage - modern good ones are within 0.2 dB 15Hz to 20kHz.

And then we throw this into a room with speakers which may have a max SPL of say 105db - subtract the noise floor at 50 if you are lucky add 3dB because we can discern stuff in the noise floor and we end up with 58dB, but then we turn on the aircon or the wife gets the vacuum cleaner out or we have some horrible room modes and we can only really get 30-40dB dynamic range and variations of 5-8 dB in level across the audio spectrum.

Specs are fine but data source to spatial delivery is what we need to really look at and the whole delivery chain needs to work together.

I don't think with respect, that I've ever seen tech tests on CD players showing 8 - 10% distortion at high frequencies - THAT's more a vinyl issue at loudly cut side ends...

Indeed, although I wasn't keen on the very first 14 bit Philips/Marantz machines, the Sony CDP 101 was great and in it's slightly 'dry acoustic' way, still is last I heard one a few years back. What seemed to be the issue forty odd years back was actually amps with high odd-order and IMD distortion, upper mid 'peaky' speakers with serious issues of driver integration and rolled-off bass, which helped vinyl a bit tonally and of course, inappropriate knowledge (or total ignorance) of room effects.

I'll repeat that some vinyl systems tend to over-egg the reverb tails and general reverb compared to the master source and a very fine direct-scanning cartridge like a Decca (on a good day!!!), this latter pickup regarded as 'dry' in tone by ignorant subjective reviewers when in actual fact and despite the mere 20dB or so separation, a good one with good diamond profile, actually gave truthful perspectives as cut. These days, there are pickups without the Decca unreliability and fussiness (the ZYX R100 was one, the Dynavector 17D3 and in its utterly wild way, the Rega Apheta series kind-of do it too - oh yes, some Lyras can be breathtaking too, all of these ideally needing a fixed head tonearm rather than the ~200Hz compromised* detachable SME/ortofon shells ).


*I cite 'Choice resonance tests as evidence.