cart measurement vs quoted spec

Yes, well I posted too quickly here at work. That is,of course, 1 dB of channel separation. ;-)

Anyway, your Ultimate Analog Test LP has the tracks I mention. Tracks 1 and 2 on side 1. They are used for az adjustment but work pretty well for this also.

I think we both need Dre on this one.

I also used the Ulti. Analog test LP.

With titan i, phantom 2, tw raven ac, tricon phono cable into Allnic phono. I played track 2 and 3 and measured the output of the phono with PAA3 meter. I also tried using the Einstein TT choice and results are not sig. diff..

Playing the L track: Recorded 1V output at L channel, 15-25mV ( fluctuating) R channel

PLaying the R track: Recorded 1.1V output at R channel, 15-25mV ( fluctuating) L channel

I took the average value of the crosstalk so approx. 20mV. I was told to take the lower value because the higher value indicated noise in the cart.. If my wife tried to annoy me and turn on the washer & dryer, the cart puts out additional random 5-10mV. For more accuracy, you can use a filter to get rid of noise. I should apply the output ratio to the crosstalk measurement to be more precise. I am just too lazy and want to get the azimuth in the ballpark.

Crosstalk: 20log 0.02/1= -33.9db for one channel;
20log 0.02/1.1= -35.6db

Channel matching 20 log 1.1V/1V = 0.82db

This is not that accurate because I assumed the gain of the phono stage is perfectly matched. I should reverse the channel on the phono to idenfy the gain mismatch in the phono. The tracks itself may not be perfectly matched too.

My math is crude and I am not an engineer. Please correct me as needed. Always love to learn.

What's surprising to me in this exercise, I can get the most channel separation on the Phantom, second on the triplanar, no azimuth adjustment on the Davinci. Both the triplanar and Davicni throws a wider soundstage than the Graham. When optimize, Graham arm sounds very focused like some SS gear.

I cannot contribute to using an oscilloscope. Have not used one since college.

I think -15db crosstalk at 1Khz is poor. Once you lose it, you are not getting it back. I would interested in how the numbers compare at 10Khz, 15Khz and 20Hz.

The window for the >25db azimuth is small, it is easy to jump right pass it. If I make big adjustment, it never went < 20db As the numbers improve, make smaller and smaller adjustments until your back, neck, eyes gives out or reached equal and minimized crosstalk.

With the my sonic lab ultraeminent on the davinci with no adjustment, I managed a -28 to 29db crosstalk on both channels. I was either lucky to have a near vertical stylus or QC is very good. Same goes for airtight and Lyra. I will check out the dynavector next week.

After this exercise, most will see that adjusting azimuth to minimize summed output amplitude of the L & R channel playing opposing phase recording do exactly just that. It compensate for channel mismatch anywhere along the sound reproduction chain: cart, phono, pre, amp, speaker, rm acoustics ( unequal dist. to speakers). It does nothing to put the needle in the middle of the groove.

Hi Dan_ed,
that's fine, now we could be on your page... B U T a 1dB channel separation (balance variance, left vs right) would still be nothing to right home about.
With your kind of cart (and mine for that matter) we are talking smaller then 0.2dB spec --- now have I a feeling we might still not speak about the same thing...

As I mentioned:
1) channel balance (L to R imbalance) spec smaller then 0.2dB, mine was a dismal 2dB.

2) cross-talk (L or R leaking its info into the opposed channel) spec better then -28dB or -30dB, again mine was another dismal -16dB leak to right and **-10dB** (even worse)leak to the left.

I'm trying to put your DMM measurements against this, if possible.

Greetings,
Axel

Axel,

Glai hit on the keys to why our measurements are off, and this was confirmed to me by Dre. He'll be posting when he gets some time, but the short answer is we are not getting the noise floor low enough with our crude methodology.

When I use my DMM on MAX for example, I am only capturing the peaks and these are probably combined harmonics from extraneous noise. This is a problem when measuring the channel output with the test tone playing through that channel, but it is an even bigger problem when trying to measure that very small signal when the tone is playing in the opposite channel.

We need a 1kHz notch filter. ;-) That's one way to do it.

Unless you guys include a notch filter to attenuate frequencies above/below the test tone, you're wasting your time using a multi-meter.

Surface noise, intra-vinyl resonances and warp wow will muddy the signal you're trying to measure with random noise. That's why Glai's measurements were "fluctuating" (aside from the washing machine).

Been there, did that...