Vinyl Asylum

Posted by blake (A) on December 24, 2016 at 12:30:37

I recently did a mono setup that's involved strapping a modified Denon 103R here and have been living with it about a month now. My phono stage has almost infinitely variable gain adjustment (supposedly between 55-75 dB-I'm a bit doubtful that higher number can be achieved but I could be wrong-and the phono stage is a bit different, more about that in a minute) and I am finding that the output from the cartridge has increased. I sense that it has, in fact, doubled.

I had done some reading somewhere that strapping the cartridge would result in halving the internal impedance in terms of what the phono stage would see (this is probably a good thing in terms of my phono stage which has a reputation of working better with lower impedance designs). So the impedance of the 103R has probably dropped from 14 to 7 ohms. But nowhere did I see that there would be an increase in output.

The spec'd output of the 103R is .25 mV but they come with a factory spec sheet which indicated that my sample has an output around .3 mV. I've been experimenting with gain settings on my phono preamp in the past few days and I am really thinking that the output has just about doubled to around .6 mV based on listening and adjusting the gain and comparing settings to my other stereo cartridge which has very low output. Does this make any sense technically?

The one wildcard, as I mentioned, is my phono stage. It is a current mode phono stage as opposed to a typical voltage mode unit. From the TNT review a number of years ago: "In current mode the input device presents the cartridge with a very low impedance, a near-short. The cartridge generator dumps a current into this impedance, and this very same current is further on in the circuit converted to a higher voltage." That review also suggested that, with current mode setups (not a lot on the market but there are a few) that the gain available from the stage could be a bit of a "surprise" depending on cartridge and generator.

So I am wondering:

a) if strapping the cartridge should in theory increase the output using a traditional phono stage or if:
b) the perceived increase in output (or gain-maybe I'm looking at it the wrong way) is a result of the strapping combined with the current mode interface with the phono stage I'm using.

Any thoughts?