[rneedle]

Folks,

I am trying to decide between various configurations of a high gain (65-70dB) solid state phono stage  with good current output (300 ohms output impedance), a MC 0.3mv cartridge, a stepup transformer and a TVC and/or pot passive attenuator (keep it simple, eh?).  I may opt to use a high output MC without the stepup. Clearly, I am trying at all costs to avoid an active preamp.

Ultimately I will have to try permutations of the above and see what works, but I have been unable to find basic specs on the TX-102.  The primary inductance has been quoted as 200H and as 400H at 20Hz. Does anyone know what the value is?

While I am sure this question has been asked and answered, I have been unable to find it.

Thanks in advance.

[John Chapman]

Hello!


Sorry for the delayed reply. I wanted to get an actual up to date figure from S&B. In the past he has loosely described it as "gobs of inductance".  Certainly with your 300 ohm source we are infine shape and not remotely close to the upper limit of that spec.

The current tx102 has 500 henries at 100 Hz. Unfortunately I did not get a 20hz figure from him - I just asked him to report the inductance when we spoke early today. As your source is about  300 ohms output impedance it would be just fine into the tx102.  

On another note your phono stage has a decent amount of gain and unless your system is particularly insensitive (speakers and amps together) then I'd think 70db of gain at the phono would do fine without any step-up in there. In fact it would be really rare to need any step-up with that much gain at the phono stage. Most often the tx103's are used along with stages in the 40 to 50 db of gain range. In rough numbers your cartridge along with 70 db of gain at the stage would give approximately the output of a typical cd player or dac.


Hope that helps!

Thanks!

John

[rneedle]

The reason I asked is that I very well respected audio designer told me that one needs about 500H at 20Hz in order to have 0 phase error.  Otherwise, one would have problems in the (mid)bass.  Sounds like the Tx-102 is fine in this regard.

My phono (Whest) was set by the distributer at 65dB, though I can have in boosted to 72dB. From what you say, I should not worry too much about it...

Thanks again,

Richard