Separate CD-4 demodulator

[gvl_guy]

Panasonic was the only one that I can think of that used the semiconductor/strain gauge. Was there any other advantage to this type of cartridge besides the CD-4 stuff?

I remember my all-in-one Panasonic turntable with built in CD-4 demodulator had this cartridge pre-installed. Never had any problems with quad reproduction using that combo.

 

[Doug G.]

The advantage of a strain gauge cartridge or any other nonmagnetic one is the influence of inductance and its effect on frequency response characteristics is eliminated. Thus the better probability of a "purer" response and more balanced sound.

Also, hum pickup from the cartridge is eliminated.

Doug

 

[gvl_guy]

The advantage of a strain gauge cartridge or any other nonmagnetic one is the influence of inductance and its effect on frequency response characteristics is eliminated. Thus the better probability of a "purer" response and more balanced sound.

Also, hum pickup from the cartridge is eliminated.

Doug

Any thoughts as to why these never caught on, even for just regular stereo listening? I can't imagine they were very expensive if they were included on the "compact" Panasonic CD-4 turntables.

 

[Sonik Wiz]

Any thoughts as to why these never caught on, even for just regular stereo listening? I can't imagine they were very expensive if they were included on the "compact" Panasonic CD-4 turntables.

Here's something interesting:

https://www.sound-smith.com/faq/wha...-how-does-it-work-why-no-riaa-or-phono-preamp
Do keep in mind this is an info page from a website that sells strain guage carts. And if you buy from there it is very expensive.

 

[Doug G.]

I believe strain gauge cartridges didn't catch on partially because of the stigma of ceramic cartridges. People equated strain gauge cartridges with ceramic.

Also, the magnetic cartridge was too ingrained back in the seventies and people are too reluctant to try something other than the norm, even though Panasonic's strain gauge cartridges weren't all that expensive back then. Note how Micro-Acoustic cartridges didn't take the world by storm either, even though their sound has been praised many times, compared to magnetic cartridges.

Doug

 

[gvl_guy]

Here's something interesting:

https://www.sound-smith.com/faq/wha...-how-does-it-work-why-no-riaa-or-phono-preamp
Do keep in mind this is an info page from a website that sells strain guage carts. And if you buy from there it is very expensive.

Unrelated topic, but did you happen to go to their homepage? Every one of their employees was sick with COVID. Whoever wrote the main page, I assume the owner, was very sick. No idea when this was written. I dont see a date (but I'm using my phone, so....) I hope they are all getting better. So sad to see a small company so affected by this.

 

[Sonik Wiz]

Unrelated topic, but did you happen to go to their homepage? Every one of their employees was sick with COVID. Whoever wrote the main page, I assume the owner, was very sick. No idea when this was written. I dont see a date (but I'm using my phone, so....) I hope they are all getting better. So sad to see a small company so affected by this.

Yes I noticed the COVID info page. That is not their actual front page which has a another to that on the COVID page. I agree this is sad & the 1st time I've heard of a small company whose entire staff was hit by it. I can't find a date either but the latest FB post was on in early May with some more info:

https://www.facebook.com/soundsmith.inc

 

[erdz]

I met Peter Lederman of Soundsmith at the Capital audio fest 2 years ago and got to listen to his strain gauge cartridge. It was the only audio piece at the whole show that blew me away. 3D souudstage like I had never heard before.

 

[MidiMagic]

I have worked extensively with strain gages in lab work, and there is another disadvantage to strain gages. They need a power supply to work.

This means that there must be a voltage supplied to the cartridge for it to put out a signal. This means that the cartridge and tonearm wiring must be compatible with a power supply feeding the pickup.

So unless they developed a way similar to electret mics to supply power to the cartridge, there was no way to use the pickup with a standard tonearm.

Electret mics use a system called phantom power to feed power to the mic element and send signal back along the same wires. Maybe this cartridge uses the same method.

Either that or there is a button cell in the headshell.

 

[Owen Smith]

The CD-4 demodulator provides phantom power to the strain gauge cartridge.

 

[Doug G.]

Yes, a strain gauge cartridge gets its required voltage through the same wires from which the signal is sent out. I consider the requirement a very minor disadvantage.

Stand alone preamps for regular 2 channel stereo with the phantom voltage supply have been designed and built by several people on various forums. They are relatively simple devices. Me? I just use a Panasonic or Technics demodulator and play CD-4 or regular 2 channel. It sounds wonderful.

Doug

 

[Wurly1]

Magnetic cartridges produce an electric signal depending on the velocity of the movement of the stylus. The higher the velocity, the higher the voltage. So the output voltage will be higher on high frequencies and lower on low frequencies. Frequency compensation is required.
With strain gauge, the cartridge contains a semiconductor element that need to be polarized via a small dc voltage and consume only few mili-amp. The movement of the stylus cause that small current to change proportionally to the amplitude of the groves. It produce an exact electrical signal identical to the groove. No frequencies compensation required and it has a linear frequency response from DC up to 50khz.
This is why strain gauge cartridges work so well with CD-4.

 

[MidiMagic]

Magnetic cartridges produce an electric signal depending on the velocity of the movement of the stylus. The higher the velocity, the higher the voltage. So the output voltage will be higher on high frequencies and lower on low frequencies. Frequency compensation is required.
With strain gauge, the cartridge contains a semiconductor element that need to be polarized via a small dc voltage and consume only few mili-amp. The movement of the stylus cause that small current to change proportionally to the amplitude of the groves. It produce an exact electrical signal identical to the groove. No frequencies compensation required and it has a linear frequency response from DC up to 50khz.
This is why strain gauge cartridges work so well with CD-4.

Frequency compensation is always required when playing a phono record. The mono, stereo, or matrix record and the baseband of the CD-4 record are recorded with the RIAA pre-emphasis curve. Thus, it must be played with the RIAA de-emphasis curve.

The pre-emphasis and de-emphasis combination allows more time on a record side and reduces surface noise.

Before 1957, different companies used different recording curves, causing the user to change compensate for each brand of record.

I have seen compensation built into ceramic cartridges and in ICs. So it might not be visible, but it must be there.

 

[Wurly1]

Frequency compensation is always required when playing a phono record. The mono, stereo, or matrix record and the baseband of the CD-4 record are recorded with the RIAA pre-emphasis curve. Thus, it must be played with the RIAA de-emphasis curve.

The pre-emphasis and de-emphasis combination allows more time on a record side and reduces surface noise.

Before 1957, different companies used different recording curves, causing the user to change compensate for each brand of record.

I have seen compensation built into ceramic cartridges and in ICs. So it might not be visible, but it must be there.

You are right about the RIAA curve which is built-in the SC cartridge panasonic epc-451 which i use. The cartridge output is therefore not linear but it's optimized to pick-up the high frequency 30khz CD-4 carrier. Howerver the way a magnetic cartridge is built must take into account the fact that velocity will affect it's output.

 

[par4ken]

Frequency compensation is always required when playing a phono record. The mono, stereo, or matrix record and the baseband of the CD-4 record are recorded with the RIAA pre-emphasis curve. Thus, it must be played with the RIAA de-emphasis curve.

The pre-emphasis and de-emphasis combination allows more time on a record side and reduces surface noise.

Before 1957, different companies used different recording curves, causing the user to change compensate for each brand of record.

I have seen compensation built into ceramic cartridges and in ICs. So it might not be visible, but it must be there.

The output of strain gauge (and of ceramic cartridges) roughly follow the RIAA curve. If you read the literature by the manufacturer of the cartridge mentioned here it does state that there is a portion of the curve where the output deviates slightly from the actual RIAA curve. They say that in the past complex equalisation circuits were tried but that goes against their audio faith tradition. They say that the ear is more forgiving of amplitude errors than time errors. They use no equalisation in their preamps.

 

[johnny_leeman]

As I stated somewhere else already. I own the Marantz 400B, two Sansui QC-04's and a Pioneer QD-240. And although just on functionality and looks it would be the Pioneer, or the Marantz; but for me just for its main purpose playing CD-4's in all there glory,.. I must say the Sansui QC-04 wins with a land slide for me. More detailed, more treble more spacious. Also it's frequency specs make it the better one. Less basy than the Marantz or Pioneer, the latter being the most basy. (And that comes for someone like me who's a real Pioneer freak!). The Pioneer is beautiful though, and on paper maybe the best one. But in practice for me it's not!
Note: The Pioneer does rock though as an external sole stereo phono pre-amp, and that's is were I turned out to use the Pioneer for. And the Marantz is there for the looks only, even when I have a Marantz quad setup hooked up, course I use the Sansui QC-04. it's just way better then the Marantz. Also I do not have any other quad seperates of any kind with build in CD-4's demodulators for Vinyl you see, but I do have two Akai quad receivers with cd-4 demodulators build in. However my two Sansui quad receivers, do not have build in CD-4 neither.

 

[johnny_leeman]

Removed by poster

 

[johnny_leeman]

removed by poster

 

[gvl_guy]

As I stated somewhere else already. I own the Marantz 400B, two Sansui QC-04's and a Pioneer QD-240. And although just on functionality and looks it would be the Pioneer, or the Marantz; but for me just for its main purpose playing CD-4's in all there glory,.. I must say the Sansui QC-04 wins with a land slide for me. More detailed, more treble more spacious. Also it's frequency specs make it the better one. Less basy than the Marantz or Pioneer, the latter being the most basy. (And comes for someone like me who's a real Pioneer freak ;-). The Pioneer is beautifull though, and on paper maybe the best one. But in practice for me it's not!
Note: The Pioneer does rock though as an external sole stereo phono pre-amp, and that's is were I turned out to use the Pioneer for. And the Marantz is there for the looks only, even when I have a Marantz quad setup hooked up, course I use the Sansui QC-04. it's just way better then the Marantz. Also I do not have any other quad seperates of any kind with build in CD-4's demodulators for Vinyl you see, but I do have two Akai quad receivers with cd-4 demodulators build in. Although my two sansui quad receivers, do not have build in CD-4 neither.
View attachment 67490

The Pioneer has the big advantage of the adjustments on the front, too.

 

[MyCuff]

I have bypassed the phono input on my QRX-999 because it has been problematic. Obviously I can still play my QS and SQ records, but have been missing out on CD-4. How likely is it that a used CD-4 demodulator will be working correctly if it powers on? Any brands more reliable over time? I have already pulled the phono board, had QRX restore go over it, and they said it was all good. So other than shipping the whole unit back to them, I'm out of options. What I don't want is to spend $200 on a used unit if it is likely to need repair also.