LCR phono stages we know about

One difficulty in using higher impedance LCR is that the inductance of the choke will be higher accordingly which is harder to wind. You gain some you lose some.

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Good point. That's where Dave Slagle jumped in, to design and build chokes that will work well in "high-impedance" LCR designs. Dave can create very precise modules.

One of our readers has done a little digging into the Emia phono stage. Apparently it is NOT an LCR type. Rather, it is a novel CR type wherein the high value resistor(s) in the signal path have been eliminated. In fact, my correspondent says he was told that there are NO R's or C's in the series signal path between the input stage and the output stage; All Rs and Cs are shunted to ground. (I am only the messenger here.) Thus the plate of the input tube is direct-coupled to the grid of the output tube, with all the filter components shunting to ground. I can only say it sounds great, no matter what the topology. But I really do not know how one can avoid having either an R or a C in the series signal path and still get to proper RIAA equalization. On the other hand, the two designers are smarter than I.

Hi Lewm,

Nearly a year back, we did a phono shootout, including a Thomas Mayer LCR phono, please see some of the write up in the following thread (mainly in the 2nd and 3rd page from the most recent)

http://www.1pekingroad.com/zaspx/replies.aspx?PageNo=2&topicsno=4&subjectno=1849&uppersubjectno=1849&sortby=updatedate&orderby=desc

Thekong, Thanks for mentioning the Thomas Mayer LCR phono stages. I had been meaning to do so as well. He seems to sell an LCR phono in kit form, using Dave Slagle LCR modules (aka "Intactaudio"). Very tempting. As to this shoot-out, it is not very helpful, although it seems the participants were having great fun. For one thing, several different SUTs were used with the Mayer LCR; I think the SUT will a major effect on sonics, if not THE major effect. I am somewhat familiar with the Scott Frankland phono stage mentioned. IMO, it is good but not a contender among today's best options. But you've added Thomas Mayer to our list. I wonder what he charges for that kit version?

But I really do not know how one can avoid having either an R or a C in the series signal path and still get to proper RIAA equalization.

Any tube gain stage has its inherent output impedance which can act as the invisible series resistor R in the EQ. That's been done in some designs by the late Allen Wright and others.

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