Zenith Errors

[IslandPink]

A very interesting article by Dave Slagle, here :
http://hifiheroin.blogspot.com/2021/02/ ... enith.html
http://www.intactaudio.com/forum/viewtopic.php?t=1660

[mainscablesrus]

Its fair to say 90+% of audiophiles do not have their turntable set up correctly.

[izzy wizzy]

That's a lot to digest. Thanks Mark. I had good gains with the Analogue Productions test record and the arc protractor caclulator Dave mentions. Looks like there's still more out there to be had.

[mr.natural]

Thanks for the links Mark. There’s also more links that feed off of those dealing with this by the Wallytools/Fremer camp.
I do check stylus quality with a good microscope (not USB type), so can only see general cantilever mount condition.

Lots of analysis and work to do on this via listening tests. Gonna need another long period of suspended animation from the outer world.

Could be the next phase of Lumpy Gravy.

Regards, Mr. Natural

[Wolfgang]

Testrecord and Fozgometer is the only thing that really worked for me but is completely overprized. The sound improvement was very obvious. Shouldn't be too hard to build the circuit for a fraction of the resale price.

https://www.dedicatedaudio.com/products ... ange-meter

The VTA can be much better adjusted measuring THD numbers. The M. Fremer method with USB microscope is not precise enough. Big improvement in SQ going from visual to THD adjustment.

[Nick]

Yep, should be simple to build if you know what to build...

[shane]

Doesn’t a Fozgometer just look for a null in the summed l+r outputs with an out of phase sine wave signal?

[Wolfgang]

The Fozgometer incorporates a "LogRatioDetector" developed for surround processor steering logic circuits to measure channel separation. The LEDs show which channel is ON, the signal reading of the analog meter shows the amount(voltage?) of the signal. If left and right channel show the same amount the azimuth is perfectly adjusted.

As you can see from the pics it's based on two TL074CN and one LM324. . Don't know if it that's enough information for building it together with the PCB layout,resistor values, and the data sheet of the opamps. But it would be a nice project for the many vinyl lovers of this forum.

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[Nick]

The Fozgometer incorporates a "LogRatioDetector" developed for surround processor steering logic circuits to measure channel separation. The LEDs show which channel is ON

Yep, I know I have one. But never bothered to do the work reverse engineering it. Happy for the designer to get paid for creating it. You could probably work it out from those pictures.

[Nick]

Doesn’t a Fozgometer just look for a null in the summed l+r outputs with an out of phase sine wave signal?

No its tries to let you set the cart so the difference between the signal channel and non signal channel is the same both ways around. Just finding a null would depend on the channel balance of the cartridge being perfect.

[izzy wizzy]

Doesn’t a Fozgometer just look for a null in the summed l+r outputs with an out of phase sine wave signal?

No its tries to let you set the cart so the difference between the signal channel and non signal channel is the same both ways around. Just finding a null would depend on the channel balance of the cartridge being perfect.

Is that another way of saying the crosstalk is equal across the channels?

[Nick]

Is that another way of saying the crosstalk is equal across the channels?

Yes, maybe. You use the tests tracks with left only and right only and adjust the cart until the meter gives the same reading on both tracks/

[izzy wizzy]

I found that hard on the oscilloscope; not very precise but doable. I read in a DIYAudio thread (lost it now) that a bandpass filter centered on the test frequency can stabilse things.

[mr.natural]

Would be interesting to know after azimuth testing with a meter if many cartridges are not level in line with a small head shell spirit level. There again I think I read in one of Mark’s links that a lot of small spirit levels were not accurate and were binned
after many tests were carried out.

I do use one and have put a lot of trust in it but - when tilting head shell I get a higher energy level in the left channel (well, the
balance seems better between R/L).When the head shell is level & the spirit level is correct I feel the left channel is somewhat slightly receded (less detail/energy). Bloody annoying not knowing what’s going on between stylus & groove wall.

Regards, Ed

[Neal]

The opening links are for Zenith IE slew, The Foggy thing doesn’t do that...?