Eros max input

[Clive]

Would I be ok with a London / Decca cartridge feeding 5mV to 7mV into Eros?  With 50db of gain the output should be very healthy!

[Caucasian Blackplate]

Yes, the Eros will work nicely with that level of input.

[Grainger49]

Clive,

Is that you?  Ray and Scott's friend?  We met at VSAC 2003?

The overload of the Eros is much higher than the recommended 1mV and up.  I think that Paul Joppa said it was in the order of 100mV.  But don't hold me to that.

I sold the Decca cartridges back in 1974.  The positive tracing cartridge.  Beautiful sounding, but in the day, not so rugged.

[Clive]

Grainger, that's another Clive, someone I knew via forums but he's not been around for ages.

Thanks, both for your replies.  I expected overload of a tube stage to be huge.....

Londons are wonderful, much better made now than when they were Deccas.

[Paul Joppa]

Yes, I posted recently on the Seduction overload margin (and the difficulty of describing that margin, depending as is does on frequency and cartridge trackability and groove spacing limitations!)

Since both preamps have similar output stages, the maximum output is the same, so if the second stage is the limiting factor then Eros has 10dB less margin - at 1.0kHz, something like 70mV input could overload the output stage (20 volts output - 10 times greater than a standard CD player). Cartridge output below 1kHz is limited by the record groove spacing as well as the cartridge's ability to track high levels. Above 1kHz, higher cartridge output is theoretically possible and might overload the Seduction input stage, but the Eros input stage is much more difficult to overload sue to the way the circuit is implemented. In practice however, there are virtually no cartridges that can generate more voltage above 1kHz than below that frequency.

Some other numbers: 70mV is 20dB above the nominal 7mV you mentioned. Few if any recordings, and few if any cartridges, can produce a signal more than 14dB above the nominal 5cm/sec groove velocity.

[Clive]

Many thanks Paul for the explanation. I should explain the 7mV.  The Londons (Decca) output should be 5mV, this seems to vary even though they all use the same spec coils, IME Super Golds are high, Jubilee low and Reference the highest.  By comparing with other known cartridges I have estimated by ear that the Reference is around 7mV....I could easily be mistaken.