1219 tonearm wire capacitance.

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tep392
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1219 tonearm wire capacitance.

Post by tep392 » 25 Jun 2019 19:39

I'm running an ADC QLM36 Mk3 on my 1219 and it's kind of sensitive to capacitance, target is 275pf. I picked up a capacitance meter in hopes of selecting some cables that will give me the correct total capacitance. Receiver phono input is 120pf. I started by measuring the 1219's tonearm wire, which I always assumed would be low, but it measured 110pf! I was very surprised it is so high considering it's short length.

I ended up using 3ft of Mogami cable at 60pf. So total is 110+60+120=290pf. Close enough and my frequency response measurements look flat thru 20kHz. Before going thru this exercise I was using some generic audio cable and had noticed a sharp drop above 16kHz. Turns out that cable has about 300pf of capacitance!

Solist
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Re: 1219 tonearm wire capacitance.

Post by Solist » 26 Jun 2019 00:03

I might be wrong, but most of the Dual turntables were sold with Shure cartridges. And I think that Shures in general like higher capacitance. I remember someone recently suggesting around 350-450pf overall.

DSJR
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Re: 1219 tonearm wire capacitance.

Post by DSJR » 26 Jun 2019 10:25

Older Dual cables weren't low capacitance and probably deliberately. As said above, Shures liked higher capacitance and so did older Ortofons (Ortofon made a little cap block which slipped over the connector pins at the back to help correct this). ADC's changed a good bit during the production run (constant tinkering was reported in another forum 'room 'here on VE), so maybe your sample of QLM is more sensitive than most? The mkIII bodies made a pretty substantial change I believe over previous ones and gave higher output as much as anything I believe.

The whole vinyl 'thing' is full of enormous compromises anyway, so if you've settled on something you like the sound of (a flat response can emphasise groove wear and distortion if you're terribly unlucky ;) although I prefer that), then sit back, play a few records and have some fun enjoying the music :D

tep392
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Re: 1219 tonearm wire capacitance.

Post by tep392 » 26 Jun 2019 21:03

The higher capacitance wire would make sense then with those carts. The inductance of the ADC carts grew over time, getting quite high on the Mkiii carts, which I believe is why the capacitance has more affect in the audible range. In regards to response, I prefer a generally neutral response and will tweak with the tone controls as needed. My Kenwood has decent tone control with low/mid/high sliders and adjustable frequencies.
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