London Maroon with Eros2?

[aragorn723]

So I'm running a London Maroon cart on a Technics SL-1500c into a Quickie.  The cart is burned in, but I'm wondering how much better it can sound?  The 1500 has a built in phono, but I suspect the Quikie, Inter-M amplifier, and Def tech BP6Bs are all limiting factors.  Would the Eros 2 be a good match?  I see a difference in input impedance 47k on the Eros vs 33k on the London, and have heard the London likes 40db of gain (vs. the Eros 2's 50 db).  Would it still be a good match?

Dave

[Paul Birkeland]

It's easy enough to buy a pair of 33K resistors to swap out for the 47K resistors in the Eros, though I'd have to imagine that nearly everyone using that cartridge is running into a 47K load.  The Eros has very low input capacitance, so you'd want to consider how much cable capacitance you have and whether you need to add a little more to please the cartridge.  The gain won't be a problem, 4mV into a phono pre with 50dB of gain gets you 1.23V of nominal output voltage, with is pretty middle of the road as far as line level signals go.  I think it would be reasonable to consider the 40dB recommendation to be more like the minimum, and maybe 55dB is pushing toward the upper limit.

[aragorn723]

It's a little interesting, they say Input impedance is 47k, but optimal is 33k.  Maybe it's not worth thinking about the resistor swap in case I swap headshells?  Will have to do that at some point since the London can be re-tipped, but has to be sent to the factory for that.  The input capacitance is interesting, I hadn't considered that.  Can it be tested with a multimeter?  Currently running monster cable from the Quickie to the turntable. The London likes 100-300pf.

[Paul Birkeland]

Capacitance that low is tough to measure with a meter, you'd want to consult the manufacturer's specs.  There is a spare 1/4" hole on the Eros 2 plate where you could add a toggle switch to parallel a pair of resistors across the 47K input resistors to make them 33K (110K).

[aragorn723]

What's the capacitance on the Eros 2?  Did a little Google searching and found that Monster can be 240 pf.  They had another one they tested that is 100pf, got one laying around the house.  Will have to try that.  Sounds like the Eros would be good for my system, though maybe it's time to upgrade the whole system after that.

Dave

[Paul Birkeland]

I'd imagine the input capacitance of the Eros is less than 10pF. 

[aragorn723]

If I run a external phono preamp, there are two rca cables.  Do I simply add the capacitance of both to see total capacitance?

[Paul Birkeland]

No, this is per-channel.

[aragorn723]

What I meant was with an external phono preamp theres two pairs of RCAs, one set from the turntable to the phone preamp, and one set from the phone preamp to the stereo preamp.  How does the capacitance calculation work for that?  Wouldn't capacitance be higher with two sets of cables?

[Paul Birkeland]

The cables from the turntable to the phono preamp load the cartridge.  The cables from the phono preamp to your linestage load the output stage of the phono preamp, not the cartridge.

[aragorn723]

The cables from the turntable to the phono preamp load the cartridge.  The cables from the phono preamp to your linestage load the output stage of the phono preamp, not the cartridge.

Thanks Paul, I learned something new!