Cartridge options for current gain phonostages (47 Labs)

Lew:

Yes, you are indeed correct on that. Sorry, a bit of a brain lapse there. Parallel would halve the impedance while doubling the current.

I’ve been experimenting recently with both parallel and series strapping to convert stereo cartridges for mono use, trying to keep the technicalities right in my head and got that backwards!

I did not wire the Denon in series for mono, but interestingly, wiring an MC 20 Super in series (which would double the impedance) as opposed to parallel resulted in better sound quality with my Aqvox, which kind of surprised me, but I believe the current input may be closer to 3 ohms on the Aqvox as opposed to the zero that 47 Labs is quoting on the Phonocube.

Ortofon Cadenza Black might be another one for consideration for the OP but I'd be inclined to try and get the output voltage closer to .2 or .25 on the high end with all that gain in the phonocube.

I can't get my mind around the idea of hooking up the two channels in series for mono output.  I don't doubt that it works, but I am not sure I understand why.  Also, if you wire in series, is it not the case that internal resistance/impedance doubles (as you already noted) but also the output current remains the same?  (I am thinking of Kirchoff's Law.)

What is your impression of the effect on mono performance, if you've tried it both ways (series vs parallel) with the same stereo cartridge?

Yes, I had a bit of trouble getting my head wrapped around it as well.

But there was a notable difference, namely that in parallel, the sound seemed to be rolled off in the highs, slightly muffled and slightly less open/detailed and dynamic than when wired in series. My gain settings, I was surprised, remained about the same; I actually reduced the gain very slightly when I wired in series, which surprised me.

Bear in mind that this is with a current mode stage and that results would vary significantly with a conventional voltage mode phono stage as voltage will double in series.

As there's no ability to adjust for loading with the Aqvox (and most current mode stages to the best of my knowledge), I can only conclude that halving the impedance (from an already low impedance) into the Aqvox was not a good thing. Doubling it probably put it back into the 6-10 ohm range, which is still quite low.

But the results might be very different with another current mode stage depending on how the input is configured. Or with a higher starting point for internal impedance and a lower starting point for current, wiring in parallel may well have given superior results in my situation, but series clearly sounds better to me here in terms of what I am working with.

I'd welcome the input of others with conventional phono stages, like all of mine, but my experience with mono, derived by paralleling the two stereo channels, is the opposite of yours in terms of the effect on apparent hf reproduction.  High frequency response always seems to improve, compared to playing the same (mono) LP in stereo.  This is when I use the mono switch on my preamplifier, and therefore the cartridge remains the same stereo type used in stereo.  Maybe there is some intrinsic difference for current vs voltage driven phono stages.  I have never quite understood, anyway, the difference between current vs voltage drive in phono, because when you use a very low value load resistor, as is typical for LOMC cartridges, in effect you have enhanced the proportion by which the stage is driven with current.  However, if there is zero load resistance with your current-drive phono stage, that condition usually cannot be achieved with conventional stages.

I am thinking of the Transfiguration Phoenix S cartridge to with the phonocube. Has anyone heard the Transfiguration ?