LPT with low µ triodes?

[Fuling]

Good evening!

Since I´m soon to be finished with my X-Son of Zen I need a good preamp that converts the unbalanced signal from my CDP to a balanced one which is capable of driving an horribly low input impedance (470 ohms!).
For various reasons I don´t want to build a BZLS, so I´m looking into tube/hybrid territory instead.

To get straight to my question: Does LPT´s work good with low µ triodes like 12B4A?
I´m thinking 6k8 or so on the plates, CCS in the tail and Mosfet buffers on the outputs.
Would I be better of with higher µ triodes and some feedback to get the gain down?
I like the 12B4A very much and I happen to have a good number of them (quality brands) but I´m a little hesitant since I believe I´ve read somewhere that LPT´s works best with high µ triodes.

Best regards,

Daniel

[Zen Mod]

Originally posted by Fuling
Good evening!

Since I´m soon to be finished with my X-Son of Zen I need a good preamp that converts the unbalanced signal from my CDP to a balanced one which is capable of driving an horribly low input impedance (470 ohms!).
For various reasons I don´t want to build a BZLS, so I´m looking into tube/hybrid territory instead.

To get straight to my question: Does LPT´s work good with low µ triodes like 12B4A?
I´m thinking 6k8 or so on the plates, CCS in the tail and Mosfet buffers on the outputs.
Would I be better of with higher µ triodes and some feedback to get the gain down?
I like the 12B4A very much and I happen to have a good number of them (quality brands) but I´m a little hesitant since I believe I´ve read somewhere that LPT´s works best with high µ triodes.

Best regards,

Daniel

since you want to use CCS in tail,I don't see why you can't use 12B4 in LPT............
in that configuration length of tail is always critical........and with CCS your is biggest

[Fuling]

I´m thinking the same way, with a CCS in the tail the "balancing act" shouldn´t suffer due to the lack of µ.
I guess building a breadboard is the best way to find out!

[leadbelly]

Originally posted by Fuling
but I´m a little hesitant since I believe I´ve read somewhere that LPT´s works best with high µ triodes.

That's because the common mode noise rejection increases with increasing mu.

[Fuling]

So with a quiet PSU the low µ is no longer an issue? Sounds good! Thanks!

[Zen Mod]

Originally posted by Fuling
So with a quiet PSU .......................

conditio sine qua non

[Fuling]

conditio sine qua non

I feel stupid, I don´t have a clue what that means...

[Zen Mod]

Originally posted by Fuling


I feel stupid, I don´t have a clue what that means...

you know me -I mean everything

[Fuling]

I mean everything

Well, I´m still not getting any wiser

But after all it seems that I´ve had my original question answered, thanks!

[Zen Mod]

Originally posted by Fuling


Well, I´m still not getting any wiser

But after all it seems that I´ve had my original question answered, thanks!

http://www.google.com/url?sa=t&ct=re...6q2Wmpk36anY2Q