need suggestion about MC pre-pre

[inertial]

Re: LOW NOISE AND HUM MC PRE

Hi to all!

I can see that you have gone quite far and "semi-technical" with the thread, it is becoming difficult to follow

I would like to comment on transformers: while some would be inclined to use a transformer as first stage, bringing the MC level to MM levels to put it plainly, the rest of the preamp still needs to be able to "sing". Furthermore, the mentioned transformer has to be very expensive if you want to obtain high class results (unfortunately). It is by far easier to build an active stage based on some good schematics (maybe design it) than to go around shopping for good sounding MC/MM transformers.

Well, maybe not that easy having in mind the usual simple/simplish schematics garbled with hard to find tubes and mumbo-jumbo caps that can only be sourced here and there. I am always incline to critisize that attitude.

To me, it is as artful as possible to make it all vacuum tube and free of noise and hum (as much as humanly possible -- meaning "from not getting in the way of sound to virtually inaudible"). The sticker "use a transistor - go to jail" should apply here

On the other hand, prior to vacuum tubes, I used to design with OP amps. I still have (has not been dismantled, but I actually do not use it) my first "standalone" preamp for MC, which housed in a common plastic box I call "the ugly duckling". Well, the ugly duckling is dual mono (each channel on a separate circuit board) with hand selected (and huge size) polystyrene foil caps (low voltage, obviously) RIAA plus "audio grade" OP amps (like BB OPA134 and similia placed on sockets so you can change them like tubes... the PS is obviously solid state regulated, power being drawn from a "wall socket plastic housing", something like the one on your router or similar piece of IT equipment...

To cut a long story short, this preamp sounds IMPRESSIVE, while the noise and hum are MORE THAN VIRTUALLY INADUIBLE i.e. you have to play some music in order to hear that it is ON. Frankly, not because I built and designed it, very few commercial products in the highest league come close (like the various Rowlands, Krells, and similia in the behemoth class).

BUT, and that is a big BUT, the tube preamp mentioned above in the thread sounds way better, in spite of having (obviously) more noise and hum (but not that much, because if it was much than it would not be interesting). A good idea to try is calibrating important parameters of your arm-cartridge alignment (providing your arm lets you do that) like VTA and bias. With the ugly duckling, that is easy to do (not so with some xxx commercial phono preamp) but with the tube preamp it becomes a straight-forward-easy-to-do-in-a-few-steps thing to do, since you hear extremely well all the differences in nuance between the various settings you try.

Thanks for your patience in reading this.

Regards,
Alex

Thanks to you Alex!

Paolo

 

[inertial]

Good news, guys,

Have spoken with a kind guy that has given to me instructions to
modify the first stage in hybrid cascode!
Now I take to mine friend the ball..........he is very very slow!

Cheers,
Paolo

Hi guys,

thanks to exquisite kind T. Loesch in person (!) we have just started listen with hibryd cascode-fet modify. Very easy modd .
Stay tuned for listening impression............

Cheers,
Paolo