Strain Gauge catridges

[Pio1980]

:scratch2: Hmmm, ran across a Panasonic turntable that had CD-4 with no model number but a CD-4 badge on the front. My internet searches didn't reveal an exact model match and I didn't pull the cartridge. Apparently some of the TTs had built-in preamps for the CD-4.

Roger

I think they probably just came with the SCSG carts and no automuting.

 

[Susurus]

What do you mean by this Susurus? (perhaps my understnading of English is failing me here?)

Thought I had a problem (using a conventional cart) with high frequency distortion that sounded flat and 'tizzy'. Switched to my other preamp and it went away completely.\

jacques4x4 please post a pic thanks!

The dynamic range is far better than a CD, and the imaging detail is simply amazing.

For me it's the wide frequency range that I like about vinyl; CDs sound grainy on the high end especially through my E-stats.

If the phase error is re-introduced with a 1/3rd octave Graphic Equalizer I'll live with RIAA nonlinearity. It's about tradeoffs.

sregor thanks for the link.

 

[Pio1980]

I've completed 2 of the pre's and they seem to work very well indeed.
How many are using the Panasonic/Technics processor pre's for strain gauge cart stereo? I got an SE-405 with the cart but see no reason to use it for stereo since I have the much simpler and more direct self-constructed units based on another's basic circuit approach and adapted to the e-Bay preamp board kits.



Quote for context

I found someone with an EPC-450C-II to let go, I'm still on the prowl for spare 450C-II, 451, 460 cart carcasses.
Bought some preamp line stage board kits off e-Bay and am reconfiguring one of them for a front end for these carts. It's very important to ensure that the current available to the cart is limited to safe levels (4-5 mA according to someone I trust) and I have been testing that aspect at this time, the cart is still in it's box. I'm considering using LEDs as safety back-up current limiters but that may be unnecessary. Another factor is that there should be no working auto-muting on the TT/arm as it will introduce a loud 'POP' when cueing up/down.
I have yet to test the cart thru the device so no reports on performance yet, I'm being very cautious with this project

 

[jacques4x4]

jacques4x4 please post a pic thanks!

Here goes:

First the "transducer" front and then back
Second the Strathclyde table with the Grace 707 arm.
Third a couple of close ups of the cart.

 

[jacques4x4]

Here is one more picture of the warranty card and instruction book.

 

[tdat7192]

I have the Soundsmith Strain Gauge. It's on a Basis 2500 with a Vector 4 arm. McIntosh c22 preamp, MC275 IV amp, Spendor c8e speakers. Since it has it's own preamplifier, I also have it connected to my c2200 preamp, which feeds a pair of c30s and an MC240 (for other rooms).

The Strain Gauge replaced both a Grado Sonata and an Ortofon 2M Black. I found the Sonata to be too dark and the 2m to be too bright.

The Strain Gauge is...just right.

I listen to mostly hard bob jazz.

The main difference I hear is a definite improvement in how immediate the music sounds. There is a crispness to a string being plucked or a cymbal being hit that just wasn't there in my other cartridges. Not to say that it's over-extended on the high end, it's actually better balanced than anything I've heard. Low bass control is outstanding. The ability for my system to resolve soundstage is also much better. I go to a lot of live events, this is the closest I've ever gotten a stereo system to sound "live." It sounds great at low volume - the only cartridge I've ever had that does. At high volume, it's simply incredible.

My wife is passive about equipment (except how it looks) and she noticed that the sound was vastly improved.

I was able to audition the Strain Gauge at Soundsmith's facility in Peekskill, NY - the owner of the firm personally demo'd his Aida cartridge and the Strain Gauge. I thought the Aida was wonderful - but the Strain Gauge was even better, especially in that all important mid-range. It also has that sense of presence and immediacy that I've never heard anywhere else.

I don't know that I'd call it a bargain. But with the stylus being easy to remove (and the way the cartridge is built, it indexes perfectly when you put it back in), I no longer worry about the cantilever snapping housekeeper (she's gotten a few of them over the years, but she's a nice person who works hard). If she and I live another 50 years, the Strain Gauge will have paid for itself.

I bought the least expensive Soundsmith preamp to go with it - the owner, Peter Lederman told me the guts are same in every preamp - the more expensive ones have nice LED gauges and readouts.

I also met Peter at Soundsmith for a demo. Everything said above is right on. I tend towards rock and blues and it worked for those as well for all the same reasons. Fast and clean. Unfortunately it was out of my range so I ended up with the Boheme cart and the speakers, Monarch. Big, full, accurate sound out of a bookshelf speaker. As I keep saving my pennies, the Strain gauge is on my shopping list. I did like the dancing lights however of the higher priced amps.

 

[Susurus]

Hey thanks for the pics!

 

[Qilin]

DIY Stereo Pre-amp for Strain Gage Cartridge?

I've completed 2 of the pre's and they seem to work very well indeed.
How many are using the Panasonic/Technics processor pre's for strain gauge cart stereo? I got an SE-405 with the cart but see no reason to use it for stereo since I have the much simpler and more direct self-constructed units based on another's basic circuit approach and adapted to the e-Bay preamp board kits.



Quote for context

Hello Pio1980, I recently acquired a Panasonic 451C strain gage cartridge. I am quite interested in your comments about the DIY unit that you have created for your strain gage cartridge. Can you provide construction details, circuit diagrams, links to kits, etc. that might help me get started on this? I visited Soundsmith about two years ago, and had an audition of their strain gage cartridge system. I thought it was fantastic. I've been wanting to try to recreate that experience with a DIY system. I think a minimalist stereo preamp (without Quad decoder) for the 451C would be a great project! How do you like your system?
Best regards, DM

 

[Pio1980]

I'd be delighted to help you get yours going. I just got an EPC-451C with a bad stylus from the TT Redikilowatt found at a thrift mentioned earlier. Works fine with an aftermarket stylus but needs to be played in.

I'm still dialing in the NOS EPC-450-II on an SL-1600MkII with the muting internally disabled, played a very familiar disc thru it (Gary Numan's -Tubeway Army, 'Replicas') and was very impressed like hearing it revealed for the first time as the cliche' says. Being able to dial in the VTA by ear is critical with the original nude Shibata stylus tip. The aftermarket bonded tip I set it up with gives a good hint of what it's about but sounds somewhat dull compared to OEM so far, tho still mightily impresses with old classic discs Like Frank Sinatra's "Only The Lonely" original stereo pressing. Frank sounded lifesized and in the room.

Your cart will need to go into a TT without automute or with automute disabled! Lou Dorren (developer of CD-4) recommends the left channel cart leads be reversed with this pre's unique configuration, this only affects electrical polarization and not acoustic polarity.
Re DIY super-low noise high-gain stereo pre for strain gauge;
Search e-bay specifically for "OPA2604 Servo Preamplifier Kit AMP board kit for DIY" and order one or two, they are ridiculously cheap for what you get. It'll take some time to arrive. Additionally you will need a couple of ca 5k metal film 1/4 or 1/8 resistors for the cartridge current limiter loads, a 25-30 volt CT 150ma power transformer, case, RCA sockets and miscellaneous hardware to complete a usable pre. I'll try to get pix up soon of the mod'ed board, everything for it except the 5k loading resistors comes with the board. Do not assemble board without having the mod procedure, it'll save some backtracking and unnecessary steps.
This pre has sufficient gain and output to drive the power amp directly, using the supplied pot as an output attenuator tho' the performance deserves a stepped precision passive level control.

 

[Qilin]

Hello Pio1980,
Thanks for your advice and help to get me going! I'm not an electronic tech, but I can follow instructions, and I can solder, fabricate, etc.
I got my EPC-451C on a Panasonic CD-4 turntable, model SL-721. I ordered a new shibata stylus from Jico, but it hasn't arrived yet. The one that came on it sounded distorted. I also 'harvested' the circuit board from inside the turntable, but I'm thinking I won't be using it, in favor of going the DIY dedicated stereo preamp as you have outlined.
Best regards, DM

 

[Qilin]

Hello again Pio1980,
From which seller did you order your OPA2604 kit? Why should I consider getting two or one?
Best regards, DM

 

[Pio1980]

Hello again Pio1980,
From which seller did you order your OPA2604 kit? Why should I consider getting two or one?
Best regards, DM

e-Bay Member id along1986090
Order 2 just for the heck of it. The 2nd one can be a back-up or a basic clean line pre as-is.

 

[Pio1980]

I think you'll be better off with the homebrewed pre rather than the internal unit but save it since it 'goes' with that cart for CD-4 settings if you ever get interested in CD-4 4-channel repro.
This cart deserves a good TT, what will you be putting it on?

 

[Susurus]

On Sat I played my WIN on the PX-3 at the PNW event for a crowd of ~40 AKers...perhaps they can offer reviews?

 

[Qilin]

I think you'll be better off with the homebrewed pre rather than the internal unit but save it since it 'goes' with that cart for CD-4 settings if you ever get interested in CD-4 4-channel repro.
This cart deserves a good TT, what will you be putting it on?

Hello Pio1980,
My primary turntable has been a KAB'ed Technics SL-1200 Mk2. Also, I just got a near-mint JVC QL-Y5F and I am liking the sound of it.
Best regards, DM

 

[HypnoToad]

I checked out the Soundsmith on the Strain Gauge carts, seems like they are fantastic, but whoa they do cost a LOT!!!

 

[Pio1980]

You will want on-the-fly VTA adjustment to get the most out of this cart and the KAB/1200 has no automute to disable. I'm using a ca 6 gram spacer plate with my cart to make weight and get some reaction mass on it, an addl ca 1/16"-1/8" spacing for the cart couldn't hurt as well. Do not discard the original stylus, it may eventually be rebuildable.
The JVC looks like a shoo-in for a conventional cart 2nd TT.

 

[Qilin]

I checked out the Soundsmith on the Strain Gauge carts, seems like they are fantastic, but whoa they do cost a LOT!!!

Hello HypnoToad,
Yes I agree the Soundsmith strain gage cartridge system seems expensive to me, too. But the price includes pre-amp and cartridge together. I can attest, from my personal visit and audition there, the system sounds fantastic!
Best regards, DM

 

[Qilin]

I'd be delighted to help you get yours going. I just got an EPC-451C with a bad stylus from the TT Redikilowatt found at a thrift mentioned earlier. Works fine with an aftermarket stylus but needs to be played in.

I'm still dialing in the NOS EPC-450-II on an SL-1600MkII with the muting internally disabled, played a very familiar disc thru it (Gary Numan's -Tubeway Army, 'Replicas') and was very impressed like hearing it revealed for the first time as the cliche' says. Being able to dial in the VTA by ear is critical with the original nude Shibata stylus tip. The aftermarket bonded tip I set it up with gives a good hint of what it's about but sounds somewhat dull compared to OEM so far, tho still mightily impresses with old classic discs Like Frank Sinatra's "Only The Lonely" original stereo pressing. Frank sounded lifesized and in the room.

Your cart will need to go into a TT without automute or with automute disabled! Lou Dorren (developer of CD-4) recommends the left channel cart leads be reversed with this pre's unique configuration, this only affects electrical polarization and not acoustic polarity.
Re DIY super-low noise high-gain stereo pre for strain gauge;
Search e-bay specifically for "OPA2604 Servo Preamplifier Kit AMP board kit for DIY" and order one or two, they are ridiculously cheap for what you get. It'll take some time to arrive. Additionally you will need a couple of ca 5k metal film 1/4 or 1/8 resistors for the cartridge current limiter loads, a 25-30 volt CT 150ma power transformer, case, RCA sockets and miscellaneous hardware to complete a usable pre. I'll try to get pix up soon of the mod'ed board, everything for it except the 5k loading resistors comes with the board. Do not assemble board without having the mod procedure, it'll save some backtracking and unnecessary steps.
This pre has sufficient gain and output to drive the power amp directly, using the supplied pot as an output attenuator tho' the performance deserves a stepped precision passive level control.

Hello Pio1989,
Can you provide a link or a part number for the recommended power transformer? Also, where is a good place to get enclosures?
I've ordered the OPA2604 preamplifier kits.
Best regards, DM

 

[Pio1980]

I used salvaged junker transformers from obselesced trunk modems and such, Radio Shack and other suppliers have cases or you can 'wing it' with whatever will work. RS may have transformers for not too much, Mouser or Digikey should as well. I don't do much finished DIY so some help from the studio audience would be appreciated here.
PM sent regarding good cheap stylii.