Cartridge Capacitance and Eros

[Bryon]

I’ve been looking around for a replacement for my beloved Zyx Airy 3 as it's getting pretty long in the toot [close to 2000 hours] Zyx will retip the cartridge but at a very high cost.  I thought about having a third party, like Soundsmith retip it but the possibility of changing the sound dramatically worried me. 

There were a number of contenders – including a new Airy 3 or 4D, but my desire to try something new won out.  Having read all the hype about the new Soundsmith cartridges and after reading the comments from people whose opinions I have come to trust, I just bought a very lightly used The Voice medium compliance cartridge with the ebony body to use with my Moerch UP-4 tonearm.  It would have been nice to have heard the cartridge first but that is one of the prices you pay for living in paradise.

Soundsmith states that The Voice doesn’t need a step-up transformer before a phono preamp like the Eros, so that gets rid of a few connections and another site of potential sonic degradation.  Its output voltage is listed at only .6 mV so I’m not so sure that it will work without a bit of a boost.  Oh well, my system has way too much gain and I’ve been thinking about what the best way to tame it a bit at any rate, so maybe this will solve another problem.

I was initially concerned about compliance and resonant frequencies but after some research found that the one of the replaceable arm tubes I have for the UP-4 should work well and the resistance matches the Eros at 47k.  So far, so good. 

What I am concerned with, and don’t really understand, is the capacitance which Soundsmith says is 100-200 pf.   Paul said in an earlier post that the Eros is 10pf and while I’m not sure what capacitance my cables are, from what I understand they usually are about 75 to 150 pf.  Then there are the cables from the Eros to the Foreplay – should I be considering that? 

I’m not even totally certain whether the capacitance of the cartridge should be less than, equal to, or greater than the capacitance of the Eros, although I think the cartridge should probably have greater or equal capacitance.  Please correct me if I’m off base here.

Can anyone clarify my cloudy understanding of cartridge capacitance and reassure me that The Voice will work with my Eros.

I might still have the Airy 3 retipped by Soundsmith or another rebuilder, but it will be nice to have the choice between two reportly drastically different cartridges.

Thanks for your input

Bryon

[Paul Joppa]

Most often, a cartridge manufacturer will specify a capacitance load that optimizes the cartridge frequency response. This will be the 'table to phono preamp cable capacitance, plus any inherent input capacitance of the preamp itself. The output cable (phono preamp to main preamp) requirements are a function of the phono preamp; for the Eros I prefer to see 1-meter cables but I think most 2-meter cables are fine unless they are especially high capacitance.

The capacitance load that gives the best sound is not always that which gives the flattest frequency response, so some experimentation is often in order. I'm just sayin' what the cartridge manufacturers can't always say ...

I looked up the specs online, and found that the standard output is 2.12mV which is just about perfect for the Eros. (The 0.6mV is at 1cm/sec rather than the standard 5cm/sec - I'm not sure why they provide that specification but it's interesting that they do.) The specified optimum load is 47K with 400pF in parallel, so you may want to experiment with some added capacitance. You can solder them in parallel with the 47K input resistor, near the input RCA jacks. I would suggest just tacking in a capacitor without wrapping the lead wire so you can try a couple different values until you settle on the value you want to stick with. Get good caps, this is an important location. Fortunately the voltage rating is not important. Be sure to let them and the cartridge break in before making any final decisions.

[Bryon]

Thanks for the quick response.

I think the standard capacitance for the voice is 100-200pf although they have a 400-600pf version available -if you read the review and saw the specs on dagogo.com, the cartridge he reviewed was the 400pf version but that was specially made for his system.

I think the one I bought is the stardard 1-200pf version - do you think I'll still need to add capacitance?

It's good to hear that the output voltage is going to work with the Eros

thanks

Bryon

[Doc B.]

(The 0.6mV is at 1cm/sec rather than the standard 5cm/sec - I'm not sure why they provide that specification but it's interesting that they do.)

I think maybe because that is the spec EMT uses, and those of course are carts which are considered by many as legendary. It would be kinda like if everyone switched to the different distance for speaker measurements that Altec used - what was it, 10 ft. instead of 1 meter?

On the topic of EMT and good sounding cartridges - we demoed the new Bottlehead Tube Phono with a Brinkmann turntable with a Brinkmann modified EMT cartridge at RMAF this year, courtesy of Philip O'Hanlon of On a Higher Note. I think that cart is spec'd at around .2mV at 1cm/sec. Helmut Brinkmann assured me that the cart would work fine with the MQ stepup transformer we were using (at, IIRC, 1:10), and he was right. The cartridge sounded quite wonderful.