Why no turntables?

[Bob from Florida]

At one point I bought a number of test records. The problem is, what would I be testing other than speed? Any other measurement would just as well show what the cartridge is doing, or alignment of the table. If there is a way useful testing can be done, I am game.

You could duplicate what Hifi News is doing when they test a turntable. This will provide some validation of other published results - in the case of the same product. Expensive eye candy turntables aside, testing products someone “new to vinyl” might acquire, would provide much needed validation to OEM specifications.
It’s going to be to be more “work” than testing DAC’s, especially while the “bugs” in the tests are worked out. Who knows, you might enjoy it enough to “spin a record” on ocassion!

 

[mhardy6647]

For whatever reason, I just kind of feel the urge to drop this here...
Stupid turntable tricks, or fun with dynamically balanced tonearms.


from the DUAL 1019 manual

 

[DSJR]

At one point I bought a number of test records. The problem is, what would I be testing other than speed? Any other measurement would just as well show what the cartridge is doing, or alignment of the table. If there is a way useful testing can be done, I am game.

You probably don't have the time to trawl through this, but the HiFi Choice Turntable books from the late 70s to late 80s (presented in the UK pages of 'worldradiohistory) have extensive consumer and tech introductions as to how their tests were done. Authored technically by Martin Colloms, you have to look beyond the subjectivism of the time to his actual methods, but it shouldn't be difficult, as extensive vibration tests were done and in one 1979 issue, an attempt to show what mats do with various decks of the time.

I confirmed first hand though, that the fixed frame or solid plinth designs are or were, incredibly sensitive to what they were placed on and where they were sited if a mid bass colouration was to be minimised or avoided. I mean, classic decks like the Micro Seiki DDX/DQX 1000 and Trio L-07D could be sonically killed if not sited properly I remember. Springy belt drives could suffer wow as the flexible belts aged.


To answer a few older posts - I have a delightful B&O Beogram 3000 from 1972 with new SP12 stylus. Sound quality is excellent and well up to mid-line Rega standards (heavy cast suspended sub chassis), but like all that followed from this brand, it's too much like an appliance for a tweaky like me, as the auto mech is rapid to start playing and return - and you can't *fiddle* with the bloody thing as it just 'works' Not my sample, but this is what it is - Much later models lightened the structure, but the 'appliance' feel remained all through.

Here's mine, about to play a favourite Thomas Dolby LP -

 

[DSJR]

For whatever reason, I just kind of feel the urge to drop this here...
Stupid turntable tricks, or fun with dynamically balanced tonearms.


from the DUAL 1019 manual

Dual tonearms were mostly dynamically balanced in all planes, meaning similar inertia horizontally and vertically. Compared to other auto decks of the period, the tonearm bearings were a class above, often using finely adjusted needle pivots in all planes. Garrard in comparison in their larger format decks used a ball race at the top of the horizontal pivot, with the spindle coupling to the lower auto-links running in a sleeve at the bottom rather than a second race as Dual did in older and lower early 70s models, Garrard's verticle bearings being spring loaded needle pivots, which were lightened in 'tension' as time went on and lower tracking weights under 1.25g became the norm (my 86SB is quite safe at 1.25g but I'd not venture below, whereas my Dual 601 and 701 will track an ADC XLM at 0.7g although the arm mass is rather too high for pickups like this).

The way Dual arm pivots can be easily tested is to balance the arm out and have it floating, then place a stamp on the headshell which should make it descend freely. the horizontal bearings are usually checked by setting the bias to .25g (usually less) and upon placing the balanced arm at disc end, it should return to the rest smoothly and without stiction. Easily achieved with my 1214, 601 and 701, my 1019 isn't as good here and I can't be bothered to take the links apart underneath to access the bearing end-float adjustment to fix it.

P.S. While I'm boring you folks to death with my Aspergic ramblings, the auto-trip parts in these Duals (and in fairness Beograms too) were incredibly sensitive and delicate, Garrard taking a few years to even begin to catch up although if oil-contamination free, they worked well.

 

[MRC01]

Skating force is adjustable and inner grooves vary in diameter, so you'd have two variable depending upon the record and cartridge's VTF.
And how would you measure this?

I'll express what I was thinking by example. Years ago I had a turntable that I set up using a dual-point alignment gauge and a test record. The test record had a blank plateau, you rest the needle in the center while the record is spinning. Without any anti-skate the skating force drags the needle toward the center of the record. You'd dial up the turntable's anti-skate knob until it was just enough to prevent that, and the needle hovered more or less in the same place in the blank.

The problem is, the skating force changes across the record from outer to inner groove, so the anti-skate has to change accordingly. In my turntable, it didn't. So the best I could do is adjust it so it's balanced at a more or less center position. This made me think it might be useful to measure the anti-skate force curve from outer to inner groove. Is it constant (like hanging a weight on a string)? Does it increase as the needle moves toward the center? Or vice versa?

 

[watchnerd]

I'll express what I was thinking by example. Years ago I had a turntable that I set up using a dual-point alignment gauge and a test record. The test record had a blank plateau, you rest the needle in the center while the record is spinning. Without any anti-skate the skating force drags the needle toward the center of the record. You'd dial up the turntable's anti-skate knob until it was just enough to prevent that, and the needle hovered more or less in the same place in the blank.

The problem is, the skating force changes across the record from outer to inner groove, so the anti-skate has to change accordingly. In my turntable, it didn't. So the best I could do is adjust it so it's balanced at a more or less center position. This made me think it might be useful to measure the anti-skate force curve from outer to inner groove. Is it constant (like hanging a weight on a string)? Does it increase as the needle moves toward the center? Or vice versa?

I think you’re misunderstanding how anti skate works.

It’s a compromise value that is going to be better or worse at different points on the record, with different LP loudness, and cart VTF.

What you describe as a bit busted is normal. You can’t pick a single value that is best in all locations

 

[MRC01]

I think you’re misunderstanding how anti skate works.
It’s a compromise value that is going to be better or worse at different points on the record, with different LP loudness, and cart VTF.
What you describe as a bit busted is normal. You can’t pick a single value that is best in all locations

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.

 

[WisEd]

Skating force is adjustable and inner grooves vary in diameter, so you'd have two variable depending upon the record and cartridge's VTF.

And how would you measure this?

Wow, even I haven't heard of that one before! Variable antiskating! You set it to the tracking force of the stylis, confirm it's not skating and and forget it! It's not a "performance" parameter but more akin to a feature that is easy to adjust, or not. Real cheap tables don't even have antiskate!

 

[DVDdoug]

Thanks for weighing-in Amir!

I've only "heard" a turntable when it was a cheap "record player" with rumble, and I've heard speed problems with a slipping belt or drive wheel. I never heard wow or flutter unless something was broken.

When I was playing records back in the analog days I was always upgrading (or wanting to upgrade) my cartridge, but I only ever owned 2 proper turntables. And... I was foolish upgrading the cartridge because it was frequency response that I was dissatisfied with and I knew the real problem was the records because there were some good ones. But somehow I felt like I was "cheating' by using tone controls/EQ... I was reading too many hi-fi magazines.

 

[watchnerd]

Wow, even I haven't heard of that one before! Variable antiskating! You set it to the tracking force of the stylis, confirm it's not skating and and forget it! It's not a "performance" parameter but more akin to a feature that is easy to adjust, or not. Real cheap tables don't even have antiskate!

I'm not aware of any table / arm that has dynamically variable anti skating.

 

[watchnerd]

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.

Measure it how in a way that is quantifiable?

The skating tests on the various LPs exist, but they're essentially tracking tests, so also dependent on alignment / cartridge.

 

[WisEd]

Measure it how in a way that is quantifiable?

The skating tests on the various LPs exist, but they're essentially tracking tests, so also dependent on alignment / cartridge.

Exactly

 

[JeffS7444]

At one point I bought a number of test records. The problem is, what would I be testing other than speed? Any other measurement would just as well show what the cartridge is doing, or alignment of the table. If there is a way useful testing can be done, I am game.

The Hifi News test reports cited by @Robin L in post 31 suggest that waterfall plots of how vibration is damped (or not) may be illuminating.

 

[MRC01]

Measure it how in a way that is quantifiable?
The skating tests on the various LPs exist, but they're essentially tracking tests, so also dependent on alignment / cartridge.

Good question. Maybe this would work: set the anti-skating to a neutral position with the arm about halfway between the outer & inner grooves. Measure the force it generates. Then move the arm and measure the force at the inner grove and the outer groove. The idea is to see whether the force changes with position, and if so, quantify the change - measure the lateral forces and the shape of the force vs. position curve.

Another way to test would be to have a test record with a blank for an entire side. Adjust the anti-skate to neutral with the arm about halfway between the outer & inner grooves. Then move the arm and see if it is also neutral at the inner groove and outer groove. If it's not (and it probably won't be), measure the lateral force. The problem with this approach is it requires a cartridge to be installed and the anti-skate likely depends on the cartridge mass and tracking force. Yet even if the forces vary, the shape of the force curve might be relatively constant, just shifted up or down.

Overall, the point is to determine whether the force remains constant, increases, or decreases as the arm moves from the outer groove to the inner groove.

 

[JiiPee]

You probably don't have the time to trawl through this, but the HiFi Choice Turntable books from the late 70s to late 80s (presented in the UK pages of 'worldradiohistory) have extensive consumer and tech introductions as to how their tests were done. Authored technically by Martin Colloms, you have to look beyond the subjectivism of the time to his actual methods, but it shouldn't be difficult, as extensive vibration tests were done and in one 1979 issue, an attempt to show what mats do with various decks of the time.

I confirmed first hand though, that the fixed frame or solid plinth designs are or were, incredibly sensitive to what they were placed on and where they were sited if a mid bass colouration was to be minimised or avoided. I mean, classic decks like the Micro Seiki DDX/DQX 1000 and Trio L-07D could be sonically killed if not sited properly I remember. Springy belt drives could suffer wow as the flexible belts aged.


To answer a few older posts - I have a delightful B&O Beogram 3000 from 1972 with new SP12 stylus. Sound quality is excellent and well up to mid-line Rega standards (heavy cast suspended sub chassis), but like all that followed from this brand, it's too much like an appliance for a tweaky like me, as the auto mech is rapid to start playing and return - and you can't *fiddle* with the bloody thing as it just 'works' Not my sample, but this is what it is - Much later models lightened the structure, but the 'appliance' feel remained all through.

View attachment 456369

Here's mine, about to play a favourite Thomas Dolby LP -

View attachment 456371

Those vintage B&Os are so damn stylish, that we may almost forgive their excessive user friendliness.

 

[amirm]

The Hifi News test reports cited by @Robin L in post 31 suggest that waterfall plots of how vibration is damped (or not) may be illuminating.

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?

 

[DSJR]

I think you’re misunderstanding how anti skate works.

It’s a compromise value that is going to be better or worse at different points on the record, with different LP loudness, and cart VTF.

What you describe as a bit busted is normal. You can’t pick a single value that is best in all locations

Bias Correction, as we old Brits call it, varies with the stylus type as well, fine line, ML and Shibata tips needing rather more in my experience, than a conical or somewhere in between, a standard elliptical type. The calibration of different tonearms varies as well, and I remember one maker's lower model tonearms having too much correction and the top model too little, easily confirmed by examining the worn styli under a proper microscope where the shape could be properly observed.

The summary in ancient magazine reviews used to be that *some* correction was better than none...

 

[watchnerd]

Good question. Maybe this would work: set the anti-skating to a neutral position with the arm about halfway between the outer & inner grooves. Measure the force it generates. Then move the arm and measure the force at the inner grove and the outer groove. The idea is to see whether the force changes with position, and if so, quantify the change - measure the lateral forces and the shape of the force vs. position curve.

Another way to test would be to have a test record with a blank for an entire side. Adjust the anti-skate to neutral with the arm about halfway between the outer & inner grooves. Then move the arm and see if it is also neutral at the inner groove and outer groove. If it's not (and it probably won't be), measure the lateral force. The problem with this approach is it requires a cartridge to be installed and the anti-skate likely depends on the cartridge mass and tracking force. Yet even if the forces vary, the shape of the force curve might be relatively constant, just shifted up or down.

Overall, the point is to determine whether the force remains constant, increases, or decreases as the arm moves from the outer groove to the inner groove.

How do you measure the lateral force it generates?

 

[Thomas_A]

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?

There is not much to measure if it is the turntable but it can be shown in different ways.

Static speed and W&F numbers
Polar plot and demodulated spectrum (noise components)

Then there is the dynamic W&F but that would be difficult without having a drag component, e.g. a second arm playing while the primary arm measures 3150 Hz.

 

[RickS]

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?

Lol, if you do not like shipping now, shipping turntables is the worst. I am OCD over packaging and is the only time I have had shipping damage.

Let somebody else deal with that pain!