vinyl coefficient of friction

[billshurv]

I have been comparing approaches. Was pleased to note a handy zero in your 75us compensation should one want to experiment with damped RIAA.

Either way I see soldering in my near future!

 

[billshurv]

Funny seeing phono and google together while talking about circuits from the 80's

The internet knows all! Actually its quite interesting to watch as at least people can go places to try and understand things that have been forgotten, but you can also see where 'facts' start to get propagated.

 

[scott wurcer]

Indeed, seems Barney Oliver's was in the public domain in the 1970s.

About 4 years back I came up with what I thought was a neat topology for a true transimpedance phono input stage, including how to solve the awkward incorrect filter pole with arises from the natural LR of the cartridge. Only to find this in the search, from 1982, which already discloses it:

So much for prior art. I suspect any phono stage that had to be user tweaked for each cartridge would have limited commercial appeal.

Now you have me wondering about straight into a transimpedance mode amp with digital de-emphasis. Inject a little inverse RIAA and compute a matched filter. Don't quite see what you gain with MC, maybe we can restart the mechanical damping from the motor assembly discussion.

 

[billshurv]

So much for prior art. I suspect any phono stage that had to be user tweaked for each cartridge would have limited commercial appeal.

Graham Slee does well out selling adjustable RIAA curves for people who probably don't own any records that aren't RIAA, so sure some would like it.

Autocal of course would be loved my many except trad flat earthers!

 

[scott wurcer]

Autocal of course would be loved my many except trad flat earthers!

That's the idea, just like room EQ.

 

[billshurv]

if you can get a suitable test record. Or MEMs vibration stand to wiggle the needle.

'There's a hole in my bucket'...

 

[scott wurcer]

if you can get a suitable test record. Or MEMs vibration stand to wiggle the needle.

'There's a hole in my bucket'...

Maybe a scratch (impulse)? Remember Peter Cook in the original Bedazzled?

Can't get any good sins these days, must be the wages.

 

[billshurv]

A film they destroyed in the remake!

So impulse response to calcualate cart/arm/cable etc response then RIAA on top of that in one chunk of sums? Might also give azimuth and antiskate in the same thing.

 

[scott wurcer]

Just thinking out loud for now.

 

[luckythedog]

Now you have me wondering about straight into a transimpedance mode amp with digital de-emphasis. :scratch1

Digital or analog, the same job is there to be done........it relaxes requirements on the 1st stage if one isn't trying to squeeze a bit of compensation out of it at the same time though, either way.

 

[luckythedog]

Might also give azimuth and antiskate in the same thing.

You lost me there, Bill.....?

 

[billshurv]

azimuth you normally set with an L-R null. If you put in a mono impulse and digitise you 'might' be able to calculate how far out it is with one shot.

Antiskate was TBH a mad guess without thinking, but sure there is something that could be inferred.

 

[billshurv]

Having mulled more, you need to compare distortion between channels to calculate antiskate. With an impulse response I don't think that could be done, but certainly something you could do with a high level mono sine wave on a test record.

 

[scott wurcer]

Digital or analog, the same job is there to be done........it relaxes requirements on the 1st stage if one isn't trying to squeeze a bit of compensation out of it at the same time though, either way.

Just thinking about the dynamic headroom issues. BTW, in looking up stylus wear photos for someone else I came across a thread where someone detected stylus wear by an increase in crackle when a fresh cart is quiet on the same record.

 

[gpapag]

if you can get a suitable test record. Or MEMs vibration stand to wiggle the needle.

'There's a hole in my bucket'...

“High Frequency Testing of Gramophone Cartridges using an Accelerometer”
http://www.bksv.com/doc/TechnicalReview1976-2.pdf

Please note the discrepancy btn the test record curve and the accelerometer curve at HF, due to vinyl-grove compliance/tip mass interaction.
The test record curve is a system response, the accelerometer curve is a component response.

See also this:
“Calibration and Standards. Vibration and Shock Measurements”
http://www.bksv.com/doc/TechnicalReview1981-4.pdf

George

 

[billshurv]

Nice find. I need to call you 'Dr. Google'! I will read those carefully.

 

[scott wurcer]

Please note the discrepancy btn the test record curve and the accelerometer curve at HF, due to vinyl-grove compliance/tip mass interaction.
The test record curve is a system response, the accelerometer curve is a component response.

That sort of makes it useless in this application, though in general these graphs cast a shadow on worrying over +-.1db RIAA.

 

[billshurv]

But it does suggest that chasing low mass in your cart (VST-V, AT-150 etc) is a worthwhile pursuit IF you want maximum fidelity.

 

[jan.didden]

azimuth you normally set with an L-R null.

I've done that measuring x-talk L>R and R>L and phase delta, and setting az to where they are the same. See attached, I would set it at + 0.5 degr.

Jan

 

[Pano]

azimuth you normally set with an L-R null. If you put in a mono impulse and digitise you 'might' be able to calculate how far out it is with one shot.

I believe a few of us do something similar. When I set up a phono cart I digitize and look hard at the results for a lot of things, azimuth being one of them. Test records and mono pressings are helpful.