Aesthetix vs. Allnic vs. ARC ph7

Dear SBrown,
I don't blame you for missing the answers to your questions in reading my rather dense post. The Janus uses only two capacitor values in the coupling applications: 0.22uF and 2.0uF. I replaced the two 0.22uF caps used in both the line stage and phono stage sections with 300V-rated Vcaps (requires four capacitors, total). The choice of 300V rating was determined for me by the fact that they are only a bit larger than the OEM polypropylenes, whereas the 630V-rated Vcaps are quite a bit fatter and longer. I replaced all of the six 2.0uF metalized polypropylene film caps with 2.0uF polystyrene film and foil capacitors. The latter are a bit larger in diameter than the originals but they do fit. I changed nothing else; the tubes are still the OEM ones. The transformation in sound was quite remarkable, more obvious than expected.

I do also have a new tube set from Jim McShane, but I have not installed them as I see no reason yet to do away with the OEM tubes.

One thing that has not yet been addressed in this thread is impedance compatibility. If the OP is using the MC601 preamp listed in his system description, and plans to connect the phono stage to any of the preamp's inputs other than the unbalanced "tuner" and "aux" inputs (which have 50K input impedances), there may be issues with most of the phono stages that have been mentioned.

The input impedance of the MC601's balanced input does not appear to be specified. And the input impedances of the unbalanced inputs other than the two I mentioned above are only 10K. I'm pretty certain that a 10K load would be decidedly non-optimal for the Rhea and the Herron, and possibly also for the Allnic. And ARC specifies for the PH7 a recommended load of 50K to 100K, with 10K indicated as "minimum."

If the OP's intention is to connect the phono stage to the unbalanced tuner or aux inputs of the MC601, however, there won't be an impedance compatibility issue with any of these phono stages.

Regards,
-- Al

The 0.22uF caps are coupling caps and the 2.0uF are output caps. In the signature series, the output caps went from 2.0uF to 4.0uF so they are a load to fit in. I have 4 per side to deal with in the IO and not much room.

I've been curious on how the Vcap coppers compare to the Duelunds. At somepoint, I may replace the 1st stage coupling to the coppers to find out. It had a teflon cap in that position to begin with.

Thanks Al
My BMC phonostage is indeed connected to the unbalanced aux input of the pre.

Good point, Al.
Just found this info from the S'phile review of the Rhea:
"The preamp's output impedance was a low 110 ohms at 1kHz from the balanced jacks, this rising inconsequentially to 156 ohms at 20kHz but, more significantly, to 3846 ohms at 20Hz. This rise at low frequencies is due to the limited size of the coupling capacitors and implies that the Rhea must be used with a line stage having an input impedance of at least 30k ohms if the bass is not to sound lightweight. The output impedance from the unbalanced RCA jacks was a high 2k ohms across most of the audioband, but as this rose a relatively small amount at 20Hz, to 3.05k ohms, the preamp's tonal balance will be less affected by the line stage having a lowish input impedance."

So to those who own the Signature version, there is a logical reason why it would have a superior bass response compared to the standard Rhea. This is an easy upgrade, however. The Sig version should drive 10K ohms ok though.

Sbrown, It's a matter of semantics. "Output" capacitors can be said to be performing a coupling function, since they are in series with the linestage input (on a phono only stage).