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Input capacitance!?!?

Vinny said:
If you have the stage set with 200pF, it is too high - like I said - THIS MUST INCLUDE CABLE CAPACITANCE. There is no reason not to try towards 150pF total also. What is the cap' of the cable? Subtract that from 200pF and set that or slightly lower in the stage.

Using a suggestion above, you could well have something like 50pF in the cables!!
Click to expand...
The settings are quite limited so you can either have 100 or 200pf or above. I’ll check the cables and come back.
Thanks!
 
Vinny said:
If you have the stage set with 200pF, it is too high - like I said - THIS MUST INCLUDE CABLE CAPACITANCE. There is no reason not to try towards 150pF total also. What is the cap' of the cable? Subtract that from 200pF and set that or slightly lower in the stage.

Using a suggestion above, you could well have something like 50pF in the cables!!
Click to expand...
Capacitance is 97.2. Should I set to 100pf then.
 
The default for many phono pre amps is around 200pf and seems to be a throwback to a time when many popular (Shure/Ortofon/Jelco OEM) carts wanted to see 300+ pf.
These days the expected values are lower, which leaves many MMs sounding bright/shrill while also lacking upper HF extension.

Often the primary input set capacitor is just a ceramic or (hopefully) polystyrene cap sitting across the the input terminals, so very easy to modify.
Worth checking if your manufacturer or dealer is happy to change the cap. If not worth asking someone like Arkless to have a look.

I like 50pf on my MM pre amps and no higher than 100pf if it's a set value.

FWIW I think all 'enthusiast' phono pre amps should include load trimmers for both capacitance and load impedance.
It's critical for most MM class carts. Oddly enough when you do see trimmers its usually for MC load impedance which is actually far less critical!
 
I supply Arkless 640P's with 100pF as the standard setting precisely because the "standard" 150pF, 180pF or 220pf values are a little on the high side and you can always add to it (with loading plugs) but not subtract. As I said up thread I also can supply them with no input capacitor for even greater flexibility. I've even done a few for Decca cart owners with 100k input resistance and no input capacitance as they like to play with loading from about 22K up to 100K and loading plugs can then set it to anything below 100K with whatever capacitance is favoured also in the loading plugs.
 
how accurate are measurements with multimeters - ie clip on the white cart tag and a clip on the centre pin gives me 83pf. (it should be 87+ the tonearm wiring)?

i propbably know the answer
 
Martian Sunrise said:
how accurate are measurements with multimeters - ie clip on the white cart tag and a clip on the centre pin gives me 83pf. (it should be 87+ the tonearm wiring)?

i propbably know the answer
Click to expand...

It's not an issue and does not need to be particularly accurate. A ballpark figure is all you need for arm lead etc capacitance... +/- 20% or more no problem.
See my posts above if you are concerned about it as I'll probably be having a look at your unit today. I can remove all input capacitance if desired and it can then be set to whatever you want by loading plugs, which you will have to either make or buy from me. £10 a set if included in postage of the unit itself. As re our PM's it should be about right as it is anyway.
 
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