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In Reply to: RE: long lengths generally cause treble droop. posted by richardl on August 26, 2015 at 10:30:20
Because moving magnet cartridges have a lot of wire in them, they are somewhat inductive. When you combine this with the 15-50pF/foot of various coax cables, you can end up with quite a peak.Moving coil cartridges have fewer turns of wire so the wire's capacitance will have less effect in the audible range, but the voltage output is much lower so the long wire may lead to more noise.
Edits: 08/26/15Follow Ups:
Droopy at the very top and a horrific 8-15kHz peak from the capacitance. The hagtech stuff shows it and it measures out for a Shure V15VxMR and the Rega cart that I used. There is an article on TNT-Audio with graphs that demonstrates it for a Shure M97 something or other.
I thought Grado's are MI, and that a MI cartridge wasn't sensitive to capacitance issues. Am I wrong?
____
"The blues ain't nothin' but a low-down shakin' chill. If you never had 'em, children, I sure hope you never will"
Eddie J. "Son" House
MC escapes the capacitance effect but, has more complex gain needs and is still subject to the effects of resistance changes.
mace: It's not the MI principle as such, but the very low inductance implementation. Very low inductance regular (= high output) MMs like for example an AT22/23/24/25 or a Technics EPC205CIIL will behave pretty similarly in that regard.
Greetings from Munich!
Manfred / lini
> Very low inductance regular (= high output) MMs
Actually, low inductance = low output. Low inductance Grado MI cartridges have low output of 0.5-mV. However, their inductance is significantly higher than low-output moving coils. For example, the Audio Technica ART9 has the same low output of 0.5-mV with only 25-microhenry inductance compared to Grado's 2-millihenry inductance.
Best regards,
John Elison
Grado's also have an output of 5 mv on many of their cartridges. They give you a choice.
With a Grado Prestige series you might be able to get away with a 10' low capacitance cable, but it would be better if you got an outboard phono stage which would probably outperform the one in your old receiver?
Blue Jeans makes a cable that is 12.2 pF/foot, still seems a long way to go for a tiny signal. Those cables are stiff and unwieldy. Belden 1505F is a much thinner, more flexible cable at 17pF/foot.
There are some new inexpensive phono stages that are reportedly very nice. Emotiva makes one for $150. Vista and Lounge are $300.
Regards,
BIRD LIVES
John: You've misunderstood me there. With "very low inductance regular (= high output) MMs" I don't mean very low inductance on the absolute scale, but just very low inductance for an MM design that's still supposed to work with an MM input, i.e. models in the range between roundabout 150 and 50 mH and still an output voltage of at least roundabout 2 mV (@ 5 cm/s). Hence also my choice of examples... See now?
Greetings from Munich!
Manfred / lini
G'day all, yes the Grado's are a moving iron type of cartridge and are much less coil inductance than typical moving magnet cartridges, and as such cable capacitance has less of an effect. However the less cable capacitance the better! Regards, Felix.
Someone has probably done the analysis but the Grados have high enough output to require that they must have some inductance. Either way, I'd still be very selective of what 10ft cable I used with such low level signals.EDIT:
If this is true:
http://www.vinylengine.com/turntable_forum/viewtopic.php?t=37211Then, a high quality 10ft cable might not have that much effect.
Edits: 08/26/15
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