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Strain Gauge catridges

Pio1980 said:
Hey there!
I use the 100k/1k FB loop in my version and the noise is so very far below signal as to be insignificant.
I'd like to see an implementation using your AD823(?) battery powered approach.
The changes to Flavio's schiz would include sub'ing ca 50k precision 10-turn trimpots for the 15k LF roll-off resistors to provide variable input levels for channel balancing and losing the output caps and 1k resistors for a ca 100^ 1/2W resistors as posted previously. The best cap is no cap and these are operating in the disfavorable non-charge coupled mode due to insufficient bias. If there was an offset factor to common then it wouldn't be as bad.
Click to expand...

I was worried about all that gain and noise issues.

As I understand it you don't need the RIAA section?

There are plenty of simple twin op amp pre amps schematics, just remove the RIAA components and with a bit of tweaking of components and values, all will run of batteries especially if we use AD823's or similar.

Here's an example one with a rumble filter:

http://jsgil.mylinuxisp.com/Phono/HighPerformancePhonoPreAmp.gif

Even the P06 could me modded............
 
Review of the Panasonic EPC-450C & EPC-450C-II

OK everyone,

I have uploaded Audio Magazine's 1974 review of the Panasonic EPC-450C & EPC-450C-II strain gauge cartridges to the "Digital Docs" section of this website.

For those (like me) who have a hard time trying to find this section, from the home page you click on Forum under Site Navigation, then under AudioKarma Audio Forums you should see Digital Docs (Digital Documents).

It is entitled "Panasonic EPC-450C & EPC-450C-II Audio Magazine review". Perhaps this link will work: http://www.audiokarma.org/forums/showthread.php?t=370337

I will also be uploading the user manual documentation for the EPC-451C there as well. Perhaps this link will also work: http://www.audiokarma.org/forums/showthread.php?p=4661564#post4661564


Have fun, Professor Bizzt
 
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HypnoToad said:
I was worried about all that gain and noise issues.

As I understand it you don't need the RIAA section?

There are plenty of simple twin op amp pre amps schematics, just remove the RIAA components and with a bit of tweaking of components and values, all will run of batteries especially if we use AD823's or similar.

Here's an example one with a rumble filter:

http://jsgil.mylinuxisp.com/Phono/HighPerformancePhonoPreAmp.gif

Even the P06 could me modded............
Click to expand...

No RIAA needed or welcome with these carts. Sorry, the example pre shown is way too 'busy' to be interesting, too much redundant 'stuff' in the signal path chain of custody. Without the RIAA losses one stage without all the blocking caps should be more than sufficient. The PS is interesting tho' esp with self-noise cancelling regs subbing the 7815/7915 bits.
 
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Professor Bizzt said:
OK everyone,

I have uploaded Audio Magazine's 1974 review of the Panasonic EPC-450C & EPC-450C-II strain gauge cartridges to the "Digital Docs" section of this website.

For those (like me) who have a hard time trying to find this section, from the home page you click on Forum under Site Navigation, then under AudioKarma Audio Forums you should see Digital Docs (Digital Documents).

It is entitled "Panasonic EPC-450C & EPC-450C-II Audio Magazine review". Perhaps this link will work: http://www.audiokarma.org/forums/showthread.php?t=370337

I will also be uploading the user manual documentation for the EPC-451C there as well. Perhaps this link will also work: http://www.audiokarma.org/forums/showthread.php?p=4661564#post4661564


Have fun, Professor Bizzt
Click to expand...

:banana::banana::banana:

Thanks!! Can i upload them to VE as well?
 
Pio1980 said:
Hi Prof!
I see in the listing you posted a review of the Trio (Kenwood) Supreme 20 Photo-electric phono pickup system, the only type that Matsushita apparently never used during their prolific period of phono development.
Click to expand...

I have a New in the box supreme 20 since its 100volt version I have not really used it..
 
flavio81 said:
:banana::banana::banana:

Thanks!! Can i upload them to VE as well?
Click to expand...

Please do....

Again, I'm passing the ball to a better runner than me. I am taking a break for awhile.



P.S.
My time on Audio Karma has come to an end.
It has been an enlightening experience for me, to say the least.


Best wishes, Professor Bizzt
 
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Professor Bizzt said:
OK everyone,

I have uploaded Audio Magazine's 1974 review of the Panasonic EPC-450C & EPC-450C-II strain gauge cartridges to the "Digital Docs" section of this website.

For those (like me) who have a hard time trying to find this section, from the home page you click on Forum under Site Navigation, then under AudioKarma Audio Forums you should see Digital Docs (Digital Documents).

It is entitled "Panasonic EPC-450C & EPC-450C-II Audio Magazine review". Perhaps this link will work: http://www.audiokarma.org/forums/showthread.php?t=370337
I will also be uploading the user manual documentation for the EPC-451C there as well. Perhaps this link will also work: http://www.audiokarma.org/forums/showthread.php?p=4661564#post4661564


Have fun, Professor Bizzt
Click to expand...


I'm looking at the EPC-450C and the layout looks similar to the Win SDT 10.2 shown here, tho' the Win seemingly strongly resembles a ceramic cart with it's coupler/resolver yoke's relationship to the SG beams.
22-SGCartClose-Up.jpg
24-SGCartBottom.jpg


Can anyone verify that Panasonic basically produced a licenced knock-off of the Win for a short time before a total redesign resulted in the EPC-450C-II and subsequent models?
 
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Actually Pio, this is the EPC 450C and it has a removeable stylus. It's just a bit different than the later ones.

attachment.php


However, I do believe Panasonic didn't just license from Win. I think they bought the rights to the design so it could be they originally just copied Win's design for an early cartridge.

Doug
 

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Doug G. said:
Actually Pio, this is the EPC 450C and it has a removeable stylus. It's just a bit different than the later ones.

attachment.php


However, I do believe Panasonic didn't just license from Win. I think they bought the rights to the design so it could be they originally just copied Win's design for an early cartridge.

Doug
Click to expand...

Thnx for response Doug. I think Win still made carts after the deal so I don't know the status of the patent ownership arrangements.
The differences between The 450C and 450C-II are substantial and appear to be mostly related to the cantilever/SG element coupling and parts alignment.
The element beams are vertical in the 450C and coupled via the familiar ceramic cart style yoke, the latter iterations have horizontally aligned beams forward of the pivot point, coupled thru a compact elastomeric ring on the cantilever close to the pivot.
I don't know what form/configuration the later Win carts took tho' I understand that surplus Monster (Cable) cart bodies housed them.
 
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Well, I don't know what happened to the image from the first time I uploaded it but I had to redo it. Hence the red X in Pio's quote.

Doug
 
Doug G. said:
Well, I don't know what happened to the image from the first time I uploaded it but I had to redo it. Hence the red X in Pio's quote.

Doug
Click to expand...
Thnx Doug!
Tried to link the article with the illustrations to my prior response without success, here's again.
http://www.audiokarma.org/forums/showthread.php?t=370337

It looks like Suichi Obata at Matsushita did a considerable amount of development in the original EPC-450C first iteration with a metal yoke resolver rather than the ceramic cart style elastomeric yoke coupler. Not yet satisfied, they totally reworked it into it's last final form in the EPC-450C-II and it's decendants.
 
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I've been working on packaging the modified e-bay board interface/pre with Rat-Shak parts, a power transformer, power indicator switch and case, thot I'd share the proto thus far with the class.
 

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Passed the smoke test

It's completed, time to audition----.
 

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Pio1980 said:
It's completed, time to audition----.
Click to expand...

Hello Pio1980,
I disappeared from the thread for a while!
I am quite interested in your latest work on the project. I am really pleased with mine, that you helped me so much with!
I am soon going to be ordering an enclosure to house my preamp. I have been wondering if I should take measures to isolate the transformer, due to potential electrical/RFI/EMI interactions with the circuit board, or mechanical vibration interactions. So I have been thinking should I keep the transformer completely outboard and isolated from the rest of the preamp - two separate boxes; or should I consider a wall-wart style transformer? Or should I stop worrying, and put it all in one box?
What are your thoughts?
Interested in your audition results!
Best regards, DM
 
You can tie the two high side AC power inputs on the board together and put in ca 13.5 VAC at greater than ca 200mA from a wall wart to the tied points and the mid-common. This allows the PS on the board to function as a bi-polar voltage doubler with a remote power transformer.
 
Helo Pio1980, Thanks for the advice!
Do you think I'm being overly concerned about mechanical or electrical interactions with the transformer in the same box with the circuit?
It would be easier for me to keep the existing arrangement I have,and put it all together in one box.
Or do you think there would be audible benefits for isolation?
Bst regards, DM
 
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