Conrad Johnson Owners.com

I have a PF-1 but I don't like the extra noise that I get with using it's MM stage with my MC cartridge as I have to turn the volume up to 11. I would like to have the phono stage from a PF-2, with the extra gain for MC cartridges. Does anyone have a schematic of the PF-2 that would show the differences in the phono stages? I've tried MC step up transformers but they seem to loose a lot of the soundstage compared to the direct phono connection.

Cheers,



Cosmo

Unfortunately it appears that we don't have the PF-1 or the PF-2 schematics in our database. If you do end up hunting these down, please email them to me and I can add them to our repository.

In the meantime you can get a MC to MM transformer which should alleviate the problem. Something like this: http://www.needledoctor.com/Ear-MC4-Transformer

admin wrote: ↑Tue Sep 12, 2017 7:58 am In the meantime you can get a MC to MM transformer which should alleviate the problem. Something like this: http://www.needledoctor.com/Ear-MC4-Transformer

As I say above,

I've tried MC step up transformers but they seem to loose a lot of the soundstage compared to the direct phono connection

I also don't have "Only $2,295.00" to play with



Cosmo

Totally get that budget is a restriction. I was implying that a high end transformer could give better sound. I kind of took it that with the budget limitations the transformer was maybe not "high end gear."

The transformers I have are from Lundahl, whom I believe have a pretty good reputation. They certainly work well with my classic Dennon DL-103 + Quad 33 system, but not so good with my Koestu + PF-1.

I did contact CJ to see if there was any kind of upgrade path from the PF-1 -> PF-2 phono stage but their reply stated that there was no difference in the phono stages. Despite their own documentation saying that there is. For the PF-1:

Gain: Phono Stage 40 dB (phono overload 100 mV at 1kHz)

But for the PF-2 it is noted:

Gain: Phono Stage 40, 46, or 52 dB selectable (phono overload 65 mV at 1kHz)

This is also repeated in the PF-2 manual:

In the PF2 with phono stage, this input provides the amplification and equalization required by moving magnet and high output moving coil cartridges. The PF2 phono section offers three different gain settings, 40, 46, and 52 dB, selected by switches inside the unit. The factory setting is 40 dB. If more gain is required (eg. for a low output moving coil cartridge), unplug the unit, and remove the cover. Consult the diagram for the desired switch setting.

So there is a real difference in the phono stages of the two pre-amps. Why would they say that there isn't?

Latest from CJ is that they don't have any stock of PF-1/PF-2 boards so no upgrade is possible. I've asked about the changes to the circuit schematic that might allow me to make my own modifications, but I'm guessing that will fall on deaf ears.

So does anyone with a PF-2, that includes the phono stage, care to open up their system and document the phono stage circuit layout. Ideally they would also be in the UK, not require the MC phono stage, and be willing to swap their PF-2 for my PF-1 (plus cash). Anyone....?



Cosmo