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Technics Stock Leads Capacitance Way Too High!!

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Technics stock leads capacitance way too high!!

Postby cafe latte » 28 Jul 2010 07:09

Been trying to tweak my sure m97xe with loading, I am running it at 62k input impedence, but the difference to 47k was not great. I really like the cart but it needed something, spoke with and I decided to try 75k and still there was not much change, but of course it is not just impedence that is important, but also capacitance and the ideal combined capacitance of the arm leads and phono leads should be about 150pf assuming that the internal cap in the phono preamp is 100pf. This gives an 'ideal' for loading the sure of 250pf. All good so I removed the cart and headshell IMPORTANT!! Then using a capacitance meter measured the leads back to the arm and to my amazement the combined lead and arm wire capacitance was 305pf, adding this to the internal pre amp cap I arrived at 405pf!! Next i did a bit of experimentation using high quality interconnect cable I use to make up leads and measured DOUBLE the length of the sl1210 leads and the capacitance was just over 100pf. After that is only a short run of arm wire, and experiments with thin wire even a bit twisted showed it should onlt be a few pf's. I am not a great believer of the benefits of really high quality interconnects, but all the same it has been demonstrated in the past that high capacitance values when connected to a cart can alter the frequency response positively and in this case very negatively. Safe to say when I get five mins the stock cables are coming off!! Anyone any thoughts, I am wondering if these values may be doing my dl160 no favours??
Thanks to for all his advice.
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Postby flavio81 » 28 Jul 2010 16:03

This is excellent information!!

Time to change that cable...
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Re: Technics stock leads capacitance way too high!!

Postby vinylips » 28 Jul 2010 19:59

cafe latte wrote:Been trying to tweak my sure m97xe with loading, I am running it at 62k input impedence, but the difference to 47k was not great. I really like the cart but it needed something, spoke with and I decided to try 75k and still there was not much change, but of course it is not just impedence that is important, but also capacitance and the ideal combined capacitance of the arm leads and phono leads should be about 150pf assuming that the internal cap in the phono preamp is 100pf. This gives an 'ideal' for loading the sure of 250pf. All good so I removed the cart and headshell IMPORTANT!! Then using a capacitance meter measured the leads back to the arm and to my amazement the combined lead and arm wire capacitance was 305pf, adding this to the internal pre amp cap I arrived at 405pf!! Next i did a bit of experimentation using high quality interconnect cable I use to make up leads and measured DOUBLE the length of the sl1210 leads and the capacitance was just over 100pf. After that is only a short run of arm wire, and experiments with thin wire even a bit twisted showed it should onlt be a few pf's. I am not a great believer of the benefits of really high quality interconnects, but all the same it has been demonstrated in the past that high capacitance values when connected to a cart can alter the frequency response positively and in this case very negatively. Safe to say when I get five mins the stock cables are coming off!! Anyone any thoughts, I am wondering if these values may be doing my dl160 no favours??
Thanks to for all his advice.


very good topic . IM workin with the same thing myself with the old pioneer pl10 table. any way to measure the capacitance with a digital multi meter ? cusrious to see what I got . the table has really old cheap rca's on it and was looking at kbausa parts.just unsure which cables to get for it .is lower capacitance better to a point ? my cart is an adc qlm34 mkII on that table .great stuff on this site !! thankx
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Postby fscl » 29 Jul 2010 03:22

states:
Some ordinary digital multimeters do have a capacitance measuring range, but I think it's better to have a stand alone digital capacitance meter as I have. The one I have is not very expensive yet accurate and reliable. It is a bit of test equipment well worth having if one dabbles with turntables! Regards, .


Do you have a picture or a link / brand for your standalone digital capacitance meter?

TIA.

Fred and thinking of adding to my tool collection...... :)
Music is Everything....Except Predictable....WFUV Fan.
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Re: Technics stock leads capacitance way too high!!

Postby lini » 29 Jul 2010 12:25

cafe latte wrote: (...) Anyone any thoughts, I am wondering if these values may be doing my dl160 no favours?? (...)


No worries, capacity tweaking within the usual range is pretty irrelevant for all MCs - i.e. even high output models have such a low inductance, that the resonance peak lands far up in the ultrasonic band anyway.

Greetings from Munich!

Manfred / lini
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Postby Singlemania45 » 29 Jul 2010 12:30

G'day mate, this is the one I have. http://www.jaycar.com.au/productView.as ... rm=KEYWORD Regards, .

, from your experience what is the ideal load for most MM and HOMC. Does the cart munufacturer usually recommend a loading?
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Postby taephono » 29 Jul 2010 14:35

Where to you take these capacitance readings...at the phono cable output
?

:?
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Postby lini » 29 Jul 2010 16:56

(...) capacitance loading only affects the treble frequency response and only when substantial coil inductance is present in the cartridge (typical MM's and high output MC's). (...)


Forget MCHOs in that context - at least I'm not aware of a single model that would have an inductance anywhere near the usual inductance range of MMs. I.e. capacity tweaking only makes sense for typical MM and high inductance MIs.

Greetings from Munich!

Manfred / lini
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LCR meter

Postby josephazannieri » 29 Jul 2010 17:16

Yo capacitor measurers:

I see 's suggestion to buy a stand alone capacitance meter, and I disagree with him. I suggest an alternative that is a more practical one for me.

I use an LCR meter, which measures inductance, capacitance, and resistance. I have had mine for at least 15-20 years. It's a Tenma, sold by MCM Electronics. Works great for audio. I measure inductance and capacitance, and resistance too, since I experiment with speakers. Mine cost about $75.00 when I bought it.

Current version of mine is MCM Electronics part number 72-8155. It now costs less, $49.95. I would not use a stand alone cap meter, since I measure inductance too, and I am limited in budget. Nothing against 's suggestion, but LCR meter is more useful for me.

That's for what it's worth. www.mcmelectronics.com I am sure that there are other sources, but I have had good luck with my inexpensive Tenma meter.

Good luck from that cheap old test prober!

Joe Z.
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Postby lini » 29 Jul 2010 20:13

Joe: Depends on one's individual needs, I'd say. Dedicated capacity meters often have more ranges for a wider range of capacities as well as higher accuracy and/or resolution, especially in the lower price segment. That seems to go for your recommended LCR model, too - if you compare that to the capacity only 72-8150 (which even is a good bit cheaper).

Greetings from Munich!

Manfred / lini
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Postby Singlemania45 » 29 Jul 2010 20:30

G'day mate, well if you mean optimum capacitance loading, it varies. Over the recent years, the general trend with typical moving magnet cartridges has been within the range of 200 to 300 picofarads (overall, including tonearm wiring, interconnect and phono preamp input capacitance).

However in past years, cartridges like the Shure V15typeIII and M91ED specified a somewhat higher capacitance load in the range of 400 to 500 picofarads.

Yes most manufacturers specify an optimum capacitance load range. Essentially, capacitance loading only affects the treble frequency response and only when substantial coil inductance is present in the cartridge (typical MM's and high output MC's).

This website pretty well tells the story, although the 'real world' of cartridges can be somewhat different at times! http://www.hagtech.com/loading.html Regards, .


Thanks . Very useful. I followed the link and wondered what the "resonant frequency" means? Is this the limit of the high frequency range?
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Postby cafe latte » 30 Jul 2010 00:02

quote ...Yes the capacitance meter leads are clipped on to the RCA leads right at the end, and the headshell (and cartridge) are removed for this test as the cartridge would act as a short circuit for the meter and give very erroneous readings. Add the value of the phono preamp input capacitance to the measured value to calculate the 'overall' value of input shunt capacitance.
Just to clarify one lead to the outer sheild of the phono plug and one clip to the center pin, and remember cart off.
Hoping to do my leads at the weekend. My capacitance meter is an inductance and capacitance meter it is a UNI-T I don't know how much it cost as it was a birthday gift, nice meter though
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Postby cafe latte » 30 Jul 2010 01:13

I am guessing that cables after the phono preamp to the preamp and amp are less important as far as capacitance goes?
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Postby Rap » 30 Jul 2010 02:16

cafe latte wrote:I am guessing that cables after the phono preamp to the preamp and amp are less important as far as capacitance goes?


As far as high frequency filtering of the cartridge out put, yes, less important.
(but not irrelevant as their capacitance in line with the input load of the pre amp and amp will combine to make a RC filter of sorts)
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