Alex Kitic RPa Phono corrector and line stage

[rowuk]

This is my next project. The support I got from Alex on my RH307A Super was indeed "super".

I have most of the parts for the phono corrector in my box and am anxious to get started.


p.s. I am still to new here to be able to post links so maybe this will work:
wwwDOTtubeaudioDOT8mDOTcom/Rpa/rpaDOThtml

[Paul Barker]

Alex's Reference Preamp

There you go.

[Alex Kitic]

This is my next project. The support I got from Alex on my RH307A Super was indeed "super".

Thanks

Maybe you should mention the most interesting detail of your project - switchable equalization for several "major" emphasis curves.

My personal RPA is slightly different than published, 5670 for line stage, and E180CC as input (I use it with MM cartridges thus I don't need all the gain possible with the published version).

Besides that, after a decade of use I have made a light servicing of the power supply (small toroid for HT and rectifier heater, SMPS 12.6V for the audio tubes heaters, new caps in the audio box, slightly higher values). But the general schematics is still valid for the tubes shown on it.

[Nick]

Out of interest, why do you use grid stoppers on ecc83's I can't imagine them oscillating.

[Alex Kitic]

The ECC83 probably cannot oscillate, but ECC88 can, as well as E180CC.
It's built on PCB, so I foresaw the place for a resistor. Since I use lower values as grid stoppers, 200 to 510 ohm, the influence on frequency response is negligible, and it became a habit. With point to point I use grid stoppers instead of wire...

I actually never had any tube oscillate... could it be because I always use grid stoppers?

[Nick]

Yep, but you speak as if they have no down side, I always find that higher than necessary grid stoppers always come at a cost.

[rowuk]

This is my next project. The support I got from Alex on my RH307A Super was indeed "super".

Thanks

Maybe you should mention the most interesting detail of your project - switchable equalization for several "major" emphasis curves.

My personal RPA is slightly different than published, 5670 for line stage, and E180CC as input (I use it with MM cartridges thus I don't need all the gain possible with the published version).

Besides that, after a decade of use I have made a light servicing of the power supply (small toroid for HT and rectifier heater, SMPS 12.6V for the audio tubes heaters, new caps in the audio box, slightly higher values). But the general schematics is still valid for the tubes shown on it.

Yes, in the course of the RH307A build, I discovered a lot of common ground with Alex. I have a pretty big vinyl collection and enough does not really adhere to the RIAA curve. Alex has come up with some VERY interesting options for me. Looking at the schematic, I think his phono corrector compared to others has enough gain to match the level that my digital playback has - that prevents surprises when switching sources.

It is about a weekend worth of soldering and my record deck has been dormant for about 6 months due to other changes in my listening room.

[Alex Kitic]

Yep, but you speak as if they have no down side, I always find that higher than necessary grid stoppers always come at a cost.

You said it yourself: higher (value) than necessary always come at a cost.

But I use very low values (some would object whether these values would be effective at all - you cannot make everyone happy), thus they are not "higher than necessary", unless anything more than 0 is higher?!

And, the most evident and real cost associated with grid stoppers is reduction of high frequency response in the bandwidth, which is not a case with values I use in the circuits and positions where I use them: either because it does not matter (tailored response), or because there will be something else "downstream" that is going to influence this more heavily.

[Romy The Cat]