Phono Preamp for Strain Gauge Cartridge

[xcortes]

I'm using 6v SLAs and 1k resistors to bias the cartridge. My DC blocking resistors are 0.1uF and respone is indeed heavy on bass so I'm pretty sure the 0.68 is more adequate.

 

[keto]

Were your Kalsons responsible for that recent seismic activity???
I've got an extra set of orange-drop 0.068uF caps, if you want to try 'em.

 

[xcortes]

Ja! No, I was at an elevator at the office, not having fun with the Pany.

I'm indeed counting on using those orange drops.

 

[keto]

I'll "drop" off those 0.068uF's on my next trip in from the city. The more I listen to the LP of Sergiu Luca playing Bartok on his Carlo Bergonzi (Cremona 1733) violin, the more I think the full 12dB treble boost might be a good thing. Or is that the Nonesuch Digital curse? In terms of gain and output Z the 6EM7 would be an interesting option for this application, or maybe that super-linear 6CM7? http://frank.pocnet.net/sheets/049/6/6CM7.pdf

 

[keto]

Woohoo! The strain-gauge cartridge is now biased up/down via a C4S current "load" (R) and a C4S current "sink" (L). It doesn't really show in the picture, but all the LED's are lit. The sound is fabulous. I don't know if that's because two 3K resistors have been replaced with C4Ss, or because I'm just amazed that the idea worked. SLA batteries are set up for +/- 12vdc, R2 is 6780 and R1 is 224.

 

[xcortes]

Amazing! I have to implement the C4S in mine, I guess.

The SG with my unRIAAed Eros is a beast. I would put it against Doc's $5k jap low DCR MC anyday (just kiddin' since i've not heard the latter).

 

[keto]

I'll be curious to see what you think of the C4S version. To me the difference is not subtle. I doubt this combo is anywhere near Doc's new MC cartridge. Just a hunch. But hey, imagine a Bottlehead strain-gauge cartridge, with the SR and C4S in the cartridge itself, and the LED's lighting the grooves

 

[xcortes]

I finally purchased and received a "RIAA" tests lp and did my measurements with the uneq-ed Eros. And a couple of days ago the guys from "Emia" released their own preamp and with the release they published their measurements of the cart:

The no-EQ curve is identical to what I got and his chart is nicer than mine so I'm pasting his.

In any case. There's definitely some compensation within the cart as it doesn't behave completely like a velocity device.

Leaving aside the extremes peaks that have to be dealt with (the bottom one with the input capacitor) there's only 4 dB to boost -although the frequencies are the same-.

Saludos

 

[keto]

Looks like that input cap could also be tuned lower than 50hz. Maybe a 0.1uF (33.8hz @ 47K)?

 

[xcortes]

The red phono repro fell on my lap so now I have an Eros that I can fully devote to the project!

Stay tuned

 

[Grainger49]

Xavier,

How did I miss this thread when it came out???

An old audio buddy of mine used a Panasonic strain gauge cartridge in the mid 70s.  It was amazing but I could never find one.  This was way, WAY before ebay.

I'm staying tuned!

 

[2wo]

I used the Panasonic 451 with the Roland Research stage back in the 80's and 90's. It was outstanding, I still have it. Unfortunately the supply of cartridge's/stylus have pretty much dried up. there are a few options but they are expensive. I friend of mine who is actively working on this, ordered a stylus off the bay, which turned out to be a piece of crap knock off...John