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Strain Gauge catridges

Professor Bizzt said:
It is I..

Is there a question for me?

Best wishes, Professor Bizzt
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Professor, could you please tell us more about the history of those cartridges? For example, why didn't Panasonic continue to market them?

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Now, my friends, on my preamp schematic: I changed the 15K resistor on the initial hi-pass filter to 47K and now the bass has returned to normal levels again. You could use even more, say 56K. And increasing the 0.22uF capacitor to a higher value.


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flavio81 said:
Professor, could you please tell us more about the history of those cartridges? For example, why didn't Panasonic continue to market them?
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Hello Flavio81,

Well, first everyone should know that I'm not a real professor. This is just a nickname I was given due to some experiments I was doing at the time.

I have collected quite a bit of information on turntables and some on strain gauge cartridges, but it is all on my other computer and is quite disorganized at the moment. Most of what I once had mostly memorized is a little vague now.

I do have a 3 page article written by B.V. Pisha for the August edition of Audio Magazine 1974 that discusses and reviews both the Panasonic EPC-450C and the EPC-450C-II and describes the differences. The article makes clear why the EPC-450C-II is a better choice. The succeeding Panasonic strain gauges were all very similar to the EPC-450C-II, but not the EPC-450C. The article should be dug up on the internet if possible.

I'm sure someone on the internet has already explained the history of these cartridges and the alleged connections to Sao Win's strain gauge cartridges, so repeating that won't shed anymore light than what has already been shed.

My annual stereo buyer directories get fragmented going back prior to 1977, but I do have a directory that lists the EPC-450C-II for $64.95 in 1975.

Here is a link that has some info on the EPC-450C and the EPC-460C in Japanese: http://www.audio-heritage.jp/TECHNICS/etc/index3.html

Here is a link for the same site (not finished) in English: http://audio-database.com/

Of course there are many other sources of information.

I have been asked before why Panasonic discontinued their strain gauge lineup, and I don't have the true answer, but here is my speculation on the question:


Perhaps it was a side effect of the Panasonic-Technics transition.

Perhaps it had something to do with their strain gauges being originally developed for CD-4 quad playback and the phasing out of CD-4.

Perhaps it was more expensive to make these than magnetic cartridges.

Perhaps the average Hi-Fi buyer did not see the difference and purchased magnetic cartridges instead.

Perhaps it was too difficult to ramp up production quantities so as to make a significant enough presence in the market.

Perhaps Panasonic were making these in-house and did not want to be in the cartridge business anymore.


The possible reasons are almost endless and many of them have absolutely nothing to do with the performance capabilities of this design approach.

P.S.
Flavio, your strain gauge preamp is a blessing. The one that Pio1980 built and that I listened to sounded very nice. The resolution was excellent, and the sound was very clean and fast. Congratulations brother...


I am going to take a break from AK for awhile. I need to do this...



Best wishes, Professor Bizzt
 
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Flavio, I am having no joy searching for the Pisha Audio magazine strain gauge cart article and you seem to have a knack for websearches. Give it a whack if you would please.
 
Professor Bizzt said:
I do have a 3 page article written by B.V. Pisha for the August edition of Audio Magazine 1974 that discusses and reviews both the Panasonic EPC-450C and the EPC-450C-II and describes the differences. The article makes clear why the EPC-450C-II is a better choice. The succeeding Panasonic strain gauges were all very similar to the EPC-450C-II, but not the EPC-450C. The article should be dug up on the internet if possible.
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Professor (let us give you the honorary title),

I would *DIE* to read such an article. So far i haven't found a substantial magazine review of the EPC-450C-II (or later related carts), and my "google skill" is high.

I haven't found the article you name by Pisha. Would you please, please, please, please, pretty please, send it to me to f_egoavil (a t) hotmail.com ? Or upload it to a fileserver such as megaupload, 4shared, etc?

Professor Bizzt said:
P.S.
Flavio, your strain gauge preamp is a blessing. The one that Pio1980 built and that I listened to sounded very nice. The resolution was excellent, and the sound was very clean and fast. Congratulations brother...
Click to expand...

Thanks! Don't forget to change the 15K resistor to 47K or more. The difference in bass is substantial. I'm currently enjoying the preamp right now with an EPC-450C-II that's tracking fairly well at 1.7g, now that i've optimized my tonearm a little bit.

The sound is very, very good. CD-like clarity, in the good way, of course.

Stay tuned for the new version of the preamp. I don't post it because i don't want to post untested schematics. Also i'm considering a even more simple preamp with no active devices (purely passive), to be connected to a MM preamp input. But i don't know if the RIAA curve will match perfectly since those Panasonic cartridges are supposedly internally tweaked for RIAA match, starting from the EPC450CII onwards. That's why they sound OK without any special EQ.
 
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Pio1980 said:
Flavio, I am having no joy searching for the Pisha Audio magazine strain gauge cart article and you seem to have a knack for websearches. Give it a whack if you would please.
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I can't find it, either.

Professor Bizzt, we really need you to upload the article.
 
Flavio, I think trying to feed an MM RIAA stage would be definitely counterproductive and a giant step backward. Yours is far simpler than any MM stage as-is aside from the redundant RIAA comp, and there are some interesting ideas in the later "Rod Elliot P06 DIY Phono Preamp & PSU Review " thread pages concerning the AD823 chip on battery power you should see. What I would do to improve yours regardless is lose the output blocking cap for ca 100^ 1/2 watt resistors and ensure lowest offset.
The pre I sent the Prof had 47k roll-off loading on 0.47uF input blocking caps for extended low end BTW.
 
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Hello everyone,

Just when I thought I would enjoy a temporary retirement from AK......

I will try to get this article scanned and uploaded. Someone please tell me where to upload it or tell me how to attach it to a post here, or....

I would think the best place to upload it to would be the Docs section of Audio Karma. I think good ole Vinyl Engine should have it as well.

BTW, after digging around a bit more, I happened to stumble across a listing for RAM Audio's RAM 9210SG cartridge (and preamp combo?) in Audio Magazine's 1977 Annual Equipment Directory. The SG suffix, my vague recollection of Peter Ledermann's comments on RAM Audio, and the low cartridge body weight of 3.8 grams would tend to indicate that this was a strain gauge cartridge.

What's needed here is a complete list of all strain gauge cartridges ever made (preferably in chronological order) including the Euphonics Miniconic strain gauge.

Check out this cool review of the Miniconic by B.J. Webb in the September 1966 issue of the British magazine Hi-Fi News: http://www.saturn-sound.com/history/hi-fi, reviews.htm#Euphonics Miniconic The four part review should appear at the top of the page.


Best wishes, Professor Bizzt
 
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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.
 
Professor Bizzt said:
I will try to get this article scanned and uploaded. Someone please tell me where to upload it or tell me how to attach it to a post here, or....

I would think the best place to upload it to would be the Docs section of Audio Karma. I think good ole Vinyl Engine should have it as well.
Click to expand...

YES!! Please!!

so-much-win.jpg
 
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.
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Pio, there's also a review of the Trio Supreme 20 on VE.

The review showed that the pickup was quite developed and had nice sound.

I think the folks at Matsushita never released a capacitive cartridge, or a ribbon cartridge. Or even moving iron cartridge!! Only piezoelectric, piezoresistive (strain-gauge, "semiconductor"), MM, and MC, as far as i know.
 
I thought they'd done MI.
There are 2 types of capacitance of course, a voltage shift sensing and the FM modulation/demodulation as with Paul Weathers' FM pick-up. Stax of electrostatic headphone fame also produced a "condenser cartridge" http://www.audiokarma.org/forums/showthread.php?t=156126 that appears to be voltage sensing, much like an electret mic.. The Zenith Radionic pick-up was an RF modulator type that used a variable inductance rather than capacitance..
 
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flavio81 said:
Flavio here!! Hi fellas!!

For the ones who just arrived to the thread and need a quick and dirty preamp:

dnosjq.png


NOTE: This preamp is to be powered using 9V batteries. Do not use a power supply since if something fails in the power supply and the voltage goes way up, or there is a power surge... bye bye strain-gauge elements!!

Note the "15Hz hi-pass section" has been wrongly calculated by me. And thus it is seriouly lacking in the bass department. Change the resistor or the capacitor to a higher value (for example 2X the value). Experiment.

Of course it needs more improvements. Suggested:
- Another "balance" control (for the other channel)
- Have both strain gauge elements conected to the same +V supply and invert one of the channels using an additional opamp.

It works OK with TL072 and TL082 opamps. Noise is not intrusive.
Sound quality is good and clear as a strain gauge cartridge should sound (once you correct the "hi pass filter" for better bass). Satisfaction guaranteed.

I'm pretty sorry i cannot draw an updated schematic, i've been very busy lately. But i promise i will draw a better preamp... at least within this year ;)
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I am wondering why you chose 100k / 1k, this gives you a theoretical gain of 100 times, but using a 100k resistor will induce more noise in the circuit IMO than say a 5k / 500r combination. Just a thought.
 
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.
 
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Pio1980 said:
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.
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My next version should consider direct coupled output then. I should measure the out offset; since this out goes to the AUX in of the amplifier (100mV), i doubt offset would be an issue.
 
HypnoToad said:
I am wondering why you chose 100k / 1k, this gives you a theoretical gain of 100 times, but using a 100k resistor will induce more noise in the circuit IMO than say a 5k / 500r combination. Just a thought.
Click to expand...
The noise is acceptable using a profane, mundane TL082 opamp, so it should be even lower with a better preamp. Gain could be a little bit lower, to be honest.

As for resistor values, the higher the R value of the feedback resistor, the higher the noise, if i recall correctly. So i think it would be the other way around. But you cannot use, say, 10 ohm resistors because the opamp would overload and distort. So the gain resistors IMHO should be tuned to the particular opamp model you're working with.
 
I used the full gain for a "direct-drive" thru a level control into the power amp, I generally find the most transparent line stage is no line stage. Do an A/B with a good line level source like an SACD-capable CD player thru a good passive attenuator into the power amp vs the preamp you are presently using to see for yourself.
My experimental minimalist system as presently constituted; http://www.audiokarma.org/forums/showpost.php?p=4656681&postcount=24
 
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