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Strain-gauge cart?! SDT.10.2 Semiconductor disc transducer

Susurus

Susurus

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Strain-gauge cart?! SDT.10.2 Semiconductor disc transducer--(PICS)

Pics later. [no, pics now! :D ]

Have done a quick seach, any experience with this highly exotic apparatus?


Got a brown WINLABS SDT-10.2 semiconductor disc transducer cart and bronze/gold power source, and a Ultra Magnetics 301E-718 elliptical diamond stylus (says like Shure N-44E)

Sao Win's design, later licensed to Panasonic.

What is the little adjustment on the bottom of the PS do? The red light?

So far I found http://www.audioasylum.com/cgi/t.mpl?f=vintage&m=147019"]this info:


Thanks in advance!

2.2 grams, 1.2 g tracking force.

The moral is always go to AudioKarma events every time you can! :music: Never know what you'll take home!
 
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I have no experience whatsoever w/ strain gage based phono cartridges or their related signal conditioning, but I did spend 20 years working with strain gages as a technician, so I am very familar with them and the related signal conditioning. The preamp you posted the link to probably has the signal conditioning equipment needed for strain gage based phono cartridges (load cells?). Like you, I have been very curious about strain gages based phono cartridges and would love to hear one.

Personally, I would be very reluctant to spend a lot of money on a preamp w/ a strain gage capability when a very high quality outboard strain gage conditioning module can be purchased fairly easily and reasonably. The output of such a module could be in the range of volts, but would still need to have an RIAA equalization curve applied to it to sound right.
 
Plan to hear this later today.


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Wonder how good a cart is that can read twice what's required to track a QUAD LP--goes up to 70kHz! 3 times the width of CD-Redbook.

I don't have a macro lens so I shot through a magnifying glass. (An AK'er has my tripod...so this was hand-held) Hard to see the two transducers orthogonal to each other just above the stylus suspension.

Cart: SDT 10.2 - The PC board says WIN LABS and MITCH FREY. (yes those ELNAs in there are begging for a recappin'...don't see any pop-tops though)

There's an adjustment pot accessible from the bottom of the PS. What does it do? There's an LED between the R-L volume knobs.

Reading up says I should plug this into AUX not PHONO; NOT to use RIAA equalization because the physical properties of the device does not require it--and the more direct the better for phase/time minimal monkeying. Unless you play The Monkees. :music:

Device is Position Dependant and simpler in theory, not based on velocity like MC and MM little generators, which do require that RIAA eq to compensate for signal strength variation with distance from the tiny coils.

The stylus is removable. That's such a relief. There's even a gent who can retip the stylus if I need to...
 
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That is a very nice looking piece of equipment! I would love to fiddle around with that myself! Did you get any kind of a manual with it?

I would expect the cartridge to actually be the sensor side of two separate wheatstone bridge circuits; one per channel. The output jacks would be the bridge excitation supply and the input the bridge imbalance (music) signal. I imagine the two knobs on the top of the device sets the inital system balance or null when you first hook up the cartridge. The music signal would be the dynamic system imbalance created by the stylus moving through the record grooves. The frequency response should be fantastic!

I am surprised to hear that RIAA equilization is not required! As I understand it, the RIAA equilization is intended to correct for the changes in linear speed of the stylus traveling through the record grooves with respect to frequency of a record traveling at a constant angular velocity. Maybe it actually corrects for the electrical difference in signal induction strength vs. frequency of the normal MM or MC cartridge? In any event, you definitely wouldn't want to use your phono input because the signal strength out of the box could be a lot higher.

I'll be curious to hear how you like it. :music:

BTW, you might want to eventually replace the adjusting knobs with vernier counter knobs. That way you could record the initial balance number for each channel of each cartridge you own. Would make changing cartridges a snap as well. You might also be able to run a Soundsmith strain-gage based cartridge as well.

Just a thought..... :scratch2:
 
thunderroad I appreciate your evaluation of the setup here. The link I read about for/against RIAA on this cart type is somewhere around here, here, here.

According to the sound-smith site:

...No "RIAA" filter circuitry is required or used in our preamp - just one ULTRA clean gain stage (this is because the Stgrain Gauge is a "displacement" device, not a "velocity" sensitive device like magnetic cartridges). ...
Click to expand...

The frequency response should be fantastic!
Click to expand...

DC---> 70kHz! :yikes:

Well I've only got the one cartridge (these are just different views). Yes if I like this one I will have my eye out for a Panasonic. The SoundSmilth is pretty stratospheric but I may consider a stylus.

Some effusive reviews here and here.
 
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There's an adjustment pot accessible from the bottom of the PS. What does it do? There's an LED between the R-L volume knobs.
Click to expand...

Well then those are not what I thought at all. And the little adjuster pot on the board? That's another oddity. I was going to clean it but thought maybe it was properly adjusted by the previous owner.

At the least I'll mark where the dials seem to be best for this one...yes of course numbered/vernier would be better for recording settings. The wire between these two dial bodies is too short. Pulls one of them off-true; they cannot both be straight up at the same time LOL.
 
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..No "RIAA" filter circuitry is required or used in our preamp - just one ULTRA clean gain stage (this is because the Stgrain Gauge is a "displacement" device, not a "velocity" sensitive device like magnetic cartridges). ...

There must be some appropriate EQ curve built into the preamp. The LP is mastered with the RIAA curve to make reasonable groove spacing and stylus velocity on playback. It's not there to correct any inherent nonlinearity in the cartridge. It may be that strain gage cartridges have a characteristic non-linearity that requires a deviation from the RIAA playback EQ, or it could be that the standard RIAA curve is already built into the preamp and the words are just unclear. There absolutely needs to be some kind of EQ as the LP is not cut "flat." Far from it.
 
Actually, the cartridge is made so its response compensates for the RIAA curve applied at cutting.

And the little adjustment inside may be to set the DC voltage level required by the cartridge to operate.

Doug
 
JonL said:
..No "RIAA" filter circuitry is required or used in our preamp - just one ULTRA clean gain stage (this is because the Stgrain Gauge is a "displacement" device, not a "velocity" sensitive device like magnetic cartridges).
Click to expand...

Aaaahhhhh! You posted the key phrase; velocity vs. displacement sensor. Makes perfect sense now!

Because the strain gage is a displacement device the signal strength is directly proportional to the distance the stylus moves. In a velocity sensor the signal strength is directly proportional to the speed of stylus movement. The faster the stylus moves the higher the signal strength. So, bass frequencies involve slower stylus speeds, so the signal strength is lower than those generated at higher frequencies.

Yup, no RIAA correction needed! The raw signal strength curve vs. frequency will be flat. Cool! I'd still love to hear one! :yes:

BTW, the DC excitation signal conditioning gear that I used on load cells had a bandwidth of DC-100k Hz. So, I can definitely believe that the cartridge bandwidth might be good to 70k Hz.

You've got yourself some pretty impressive hardware there! :thmbsp:
 
Well it's an extremely low moving mass (no coil) , so the tracking could be really good indeed.

With fewer parts, it may have more longevity too. Now that I've got something to compete with the low distortion of my E-stats (and fewer xover shenanigans to boot) ---half of a BG RD75 planar magnetic set--it could get amazing here very soon...
 
The transducer is good to 70kc, the actual response would depend on the tracing resolution of the tip. 70kc ain't happening with a spherical tip.
Are replacement stylus assemblies available? There must be a lot of elastomerics in the thing like the Micro-Acoustics electrets, they don't last forever.
 
A friend owned a SG-200 with a few extra needle`s.

I have just one word: amazing!

The most natural sound I`ve ever heard.

Believe me, I have heard a lot of very expensive MC`s.

But........ also this cost you real money.
 
Re: Strain gauge cart?! SDT.10.2

WOW! I'm jealous! As a Panasonic SG user, I've always wanted to hear the Win. Enough reviews have said it's the be-all and end-all of phono sources. The Panasonics are pretty great too, but mine has been having occasional crunching sounds-- can't tell if it's failing rubber or a failing interface.

For what it's worth, if you want to try a different electronic thing, some guy on diyAudio said that feeding these things 4 volts dc across the terminals, and then going thru a capacitor into a mic preamp (in his case, on a reel to reel deck), worked pretty well.
Congrats!

--nosmok
 
Nice. I've got an RT-707 to try that with. nosmok I want to ask you 20 questions... are you tracking at 1.2 Grams? What's your amp/speakers that work best? Are you direct soldered connected to your interconnects? Which TT? My best is a PX-3, linear tracking, with a C-4 pre, or just through my R-117's AUX inputs.

Lots of speakers, see the Sig file below:
 
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Panasonic strain guage system

Here is mine. The cartridge looks like an anaconda.
As stated above, it, indeed, is truly AMAZING.
With it, I hear far greater detail, crystal clear voice and the tightest sounds of percussion.
Mine was set up by Professor Bizzt, who clued me into the offering on that auction site.

EPC-451C​
picture.php


and here is the demodulator
SE-405​
picture.php
 
Whoops, droppeed out of sight just as my name was called. Currently, I'm using the Panasonic se-405, like RDecartridge above. The epc451c is on my soon to be retired Rega Planar 3, which with its medium mass arm works OK. I think a higher mass arm might work better-- the Technics are only slightly more compliant than an SPU (though much less massive). Just plug the interface into an aux input and off you go. I usean old Audionics preamp, a old console pull tube amp and efficient speakers that change every once in a while. It sounds great on everything, and I've not really tried to optimize it.
 
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