cart measurement vs quoted spec

Hi Dave,
some dB correction.
I just veryfied the 100Hz res. level. It was 2.5 times signal level. BUT that makes it ~ 7dB and NOT 12dB. Sorry, for this misstatement.

It appears to fill in the upper bass 'floor bounce' related dip in that area of the speaker, and is therefore not actually noticable.

Axel

I meaured channel match + crosstalk on PC1, ultraeminent and titan I. All performed to spec. L & R less 1db difference (assuming phono stage gain is matched). Titan I was best in channel separation with 34db crosstalk on both channels tested with Analogue test LP (track 2 and 3) while mounted on the Phantom. On the Davinci with no Azimuth adjustment, still a manageble 29-30db. The azimuth sweet zone is tiny and easy to jump thru.

I did not measure the frequency response of the cartridge.

Thanks Glai,
just the sort of feedback, type=good, I hoped for.

Now,+++ The azimuth sweet zone is tiny and easy to jump thru. +++

On a 3 point cart mount i.e. not flat-top mounting, and in a fixed Azimuth arm like a SME V, I come to think the ~ 2 deg. stated Azimuth-test-tilt, might be a bit out-of-whack.
So let's say it's more like +/- 1 deg. at best.
Suffice to say I NEVER ever would tilt it that much, that the cart-body outer rim touch the head-shell, the max. that was tested.
A perceivable air-gap would always be still there i.e. left and right top between cart main body top and head-shell bottom.
In your experience could an Azimuth-tilt, as actually in use, of between ~ 1/4 to 1/2 deg account for a 10 times! greater channel mismatch, AND a 12dB(L)to 18dB(R) out of spec cross-talk?! I have a hard time to figure that to be so.

My suspicion is further, that the gummy / suspension settled (funny enough, always to the left in these type carts) creating this 10 thou out-of-centre cantilever.

In your experience, would such 'smallish' cantilever off-set be able to create these out of spec. measurements?

Again, I find this hard to swallow, since cantilever off-set is a 'fact of life' even with some more pricy carts --- according to what I hear.

+++ (assuming phono stage gain is matched) +++ this point HAD to come up, which is good.

On the oscilloscope measurement the amplitude mismatch was perfectly replicated by swapping channels left to right.
Next argument could be some out-of-balance cable connection. Again, no measurable difference in resistance could be noted, BUT about 0.1 ohm difference in DC cart-coil resistance between left and right!
Could this explain the (10x higher then spec) 2dB left-to-right mismatch (spec= >0.2dB)?
And also the *different* L/R cross-talk of 12dB and 18db?

But surely NOT the 12/18dB *higher* crosstalk of -16dB and -10dB vs. spec. = >-28dB!

I'd really appreciate your take on this.
Thanks,
Axel

Dre, I was thinking the same thing. Axel has a habit of sensationalizing things so I think we should question his technique. But he could also be questioning the results of a particular cartridge that really does have an issue. If that is the case, this thread loses impact. Much like Axel's other threads. ;-)

Be well, Axelwahl.

Axel,

I've done these measurements numerous times and have never seen this kind of a result, so that's why I'm cautious about condemning the cartridge at this point.

I think it would be very educational for you to test another cartridge so you can get a better handle on the likelihood of the measurements being reliable.

There are a few things that could possibly cause your numbers to be off that have nothing to do with the cartridge. The errors could also be cumulative. Again I'm not saying they are just that it deserves consideration.

- Please provide the model number of the O'scope you are using.

- Are you using the 10x probes?

- Have you verified the O'scope inputs track each other by tracing the same input signal?

- Where are you taking these measurements? (What output of your audio system are you using to feed your scope?) there is the possibility of additive and induced error...

- The area of resonance could also be possibly due to the tonearm resonance (or somewhere else in the system which is why it would be good to test another cartridge) on that note, does adding damping to your arm change your measurements?

- are you using a different amplitude settings on the O'scope to take amplitude measurements before you convert the output to dB? these amplitude settings can be off relative to higher settings which could contribute to an error in measurement.

- If this is a modern o-scope, are you using the cursors to take amplitude values OR are you using the measurement features to get amplitude values from the scope numerically? (I ask because these time based measurements can be misleading by containing more than the frequency of interest.)

- Are the gains settings for the phonostage set to the same level?

- Is the cartridge loading the same on both channels?

Depending on how you are gathering the numbers, there could be an entire spectrum of cumulative amplitude which is not exclusive to the frequency intended to be measured and this can also effect your results.

There are a number of variables that can stack up and add errors to the measured results. Some other thoughts are the crosstalk introduced by the system itself- this can be checked by sending the output of one cartridge channel into the both input (L&R) of the phonostage by using a Y-connector.

I hope this all makes sense,
Dre