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cart measurement vs quoted spec

Hi,
I'm a bit puzzled by some cart measurements performed with the ACOUSTECH test record, using HP oscilloscope and using (differential connection) through ML 326S phono-modules.

No loading (47k), measured on XLR pre-outputs. The following transpired:
Left vs. Right = *- 2dB* @ 1kHz 7cm/s lateral (mono track), *spec = <0,2dB!*
Left vs. Right = on 1kHz 7cm/s vertical out of phase track, clearly NOT EVEN CLOSE to out of phase!
1 kHz left channel only *- 16dB* leakage to right! *Spec = >28dB @ 1 kHz!*
1 kHz right channel only *-10dB* leakage to left! *Spec = >28dB @ 1 kHz!*

This seems a most disappointing showing indeed. Let me hasten to say that all variations with regards to anti-skate, VTA, VTF, Azimuth and Zenith, were attempted for any optimisation.

I shall not yet disclose the make, which is a VERY well known brand, and their TOP of the range offering.

Has any one got some explanation for how such a major variation can be the case?!

There might just be some folks out there trying there darntest by NEVER getting their apparent alignment problem fixed, please note the various threads, ---- and it might be a cart way out of quoted tolerance?

I have also noted that in this instance, MAJOR Azimuth (+/- 2 deg), VTA, VTF, changes had absolutely MINOR measured effects!
The 'biggest' in this case was 'Zenith' by some 0.5mm left turn to compensate for a 'minor' out of centre cantilever (~ 0.25mm off-set to the left).

Tonality and such is NOT really affected, BUT distortion with massed instruments/orchestra etc. i.e. as soon as things get 'busy' the problems start.

Greetings,
Axel
axelwahl
axelwahl OP
788 posts
 
:-) Wow Commcat,

maybe there is no need to test a Ferrari either.
Well, I guess we do know it's more fun to drive with correct wheel-alignment, handles the corners just a bit better.
That said, would they ever agree that an incorrect aligned one ever left their premises? Mistakes can happen on all sides --- as long as they are not too many and too often.

Axel
PS: But then also, who actually has the gear available to question a factory setting?
dougdeacon
3,338 posts
 
You can tweak-align you sweet hind off, and NEVER come right if that happens, distortion is programmed for you right in the cart.
True! Just what I was trying say in my first response.

By way of sharing experiences, I once owned an ABC model DEF with an off-line and twisted cantilever. With test record, notch filter and multi-meter in hand, I proceeded to measure channel (im)balance and crosstalk. Adjust as I would, I couldn't get anything remotely close to decent numbers. No surprise, you can't make a silk purse from a sow's ear, and I STILL say I'm inane for discussing it. :-)

I've also measured multiple samples of my current reference cartridge using the same tools and methodology. On all but one, channel balance was within 0.2db (usually less) and crosstalk was < 0.1 db (below the resolution of the meter, even when measured at the POWER amp outputs). The one sample that measured higher was replaced under manufacturer's warranty, no questions asked.
larryi
3,790 posts
 
Axelwahl,

If the cartridge in question is the Ortofon PW, is this the same cartridge that you praised as the best cartridge you have heard apart from the Transfiguration Orpheus, or is this another iteration?

I agree that your measurements are disappointing, but, I am trying to understand the correlation between the poor measurement and sound quality.
dre_j
159 posts
 
Axel,

Have you verified your measurement procedure with another cartridge?

If I had captured those numbers, they would seem to be suspect to me. I'm not saying that they are but I'd sure want to know that I can at least verify the results/technique with a different cartridge to be sure it's not a measurement error.

Dre
intactaudio
293 posts
 
[b]There is a resonant peak ~ 12dB --- can you believe it, at between 80Hz - 120 Hz!
But it does not translate into hearing it... The main issue it that whacked out channel balance. [/b]

Are you saying that a measured 12dB peak at 80-120hz is inaudible?

dave
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