Involve CD4....Is there any life in it????

[bigbillquad]

I am coming back to this post to try light the fires, For all you that want a modern day CD-4 decoder this is and is the only chance to see if Chucky can deliver a unit for us.

PEOPLE thought that when he was going to produce a SQ & QS unit it would not happen, But look he made GOOD the Surround Master......:banana:

So all how would like to own a modern day CD-4 unit please put your name here to give Chucky the encouragement he needs to pull it off.
Thanks Bill...

 

[roundhousequad]

I'm still in for one

 

[fredblue]

the ultimate CD-4 demodulator, personally, would include carrier level adjustment and separation pots fully accessible from the front panel of the unit and have crosstalk cancellation controls, plus a blend mode for those discs in less than stellar condition, plus the ability to run a low output moving coil cart thru it as well as the usual MM preamp stage.. a big ask I guess and probably beyond Involve's remit but would love something like the Technics SH-400 (I realise that doesn't handle LOMC but MM and SC carts.. also new Involve demodulator doesn't need the carrier level meters or the acres of brushed steel fascia of the Technics.. but would be gorgeous icing on the cake) rather than a box that has auto carrier and/or carrier level & separation adjustment controls round the back of the unit (these are things that drive me mad about the JVCs and the Grundig I have, I like to tinker and its much harder than it needs to be with those old boxes having to pull them out and fiddle fart around the back of them!!) ah its fun to dream..

 

[bangsezmax]

the ultimate CD-4 demodulator, personally, would include carrier level adjustment and separation pots fully accessible from the front panel of the unit and have crosstalk cancellation controls, plus a blend mode for those discs in less than stellar condition, plus the ability to run a low output moving coil cart thru it as well as the usual MM preamp stage.. a big ask I guess and probably beyond Involve's remit but would love something like the Technics SH-400 (I realise that doesn't handle LOMC but MM and SC carts.. also new Involve demodulator doesn't need the carrier level meters or the acres of brushed steel fascia of the Technics.. but would be gorgeous icing on the cake) rather than a box that has auto carrier and/or carrier level & separation adjustment controls round the back of the unit (these are things that drive me mad about the JVCs and the Grundig I have, I like to tinker and its much harder than it needs to be with those old boxes having to pull them out and fiddle fart around the back of them!!) ah its fun to dream..

To me the ultimate CD-4 box would be self-correcting -- no need for any adjustments, the software could detect the variables in the signal and handle it on the fly.

As nice as it'd be to have those LOMC options, you could do a SUT for those if you really wanted. The SC is pretty much a white elephant in the cartridge world (and I say this as someone who runs a Panasonic SE-405 and would love to own one of those strain gauge carts).

Really, I just want to see a working CD-4 decoder that isn't 35+ years old. There has to be a better, cleaner way to decode those discs than what was available in the 70s.

 

[Aristotle]

I am definitely still in for a modern CD-4 Demodulator < $1,200

 

[BigAlt]

, plus the ability to run a low output moving coil cart thru it as well as the usual MM preamp stage.. a big ask I guess and probably beyond Involve's remit but would love something like the Technics SH-400 (I realise that doesn't handle LOMC but MM and SC carts o

Since Chucky has indicated that the CD-4 Demod will Not have a built in preamp like the Technics or any of the other vintage CD-4 Demods ( since it will be designed around the SM platform (which requires an external preamp) to save on development and manufacturing costs ) you'll be able to use any cartridge and preamp combination you desire. However, because of the way CD-4 LPs were encoded, all of the CD-4 cartridges that were designed for CD-4 LPs had a very broad frequency response going up to 60kh to deliver the necessary decoding information. I believe that even the lower cost CD-4 cartridges went up to 40 to 45khz. So unless you can find a LOMC cartridge that will deliver the necessary high frequency response it may not be compatible with CD-4 LPs.

Big Al

 

[sjcorne]

If it requires an external pre-amp, one would need to find one that puts out the 45K carrier frequencies that the new SM/CD4 would demodulate . Does such a pre amp exist ?

 

[BigAlt]

If it requires an external pre-amp, one would need to find one that puts out the 45K carrier frequencies that the new SM/CD4 would demodulate . Does such a pre amp exist ?

I believe most preamps have the necessary frequency range. I have two Clearaudio Nano's and they have a frequency response of 20hz-50khz. I'm sure most others are at least as good if not better.

 

[fredblue]

mightn't there be performance diminishing capacitance issues having to loop rca's in and out from turntable to pre-amp to Involve demodulator? hmm..

 

[fredblue]

If it requires an external pre-amp, one would need to find one that puts out the 45K carrier frequencies that the new SM/CD4 would demodulate . Does such a pre amp exist ?

i've had my eye on an Ortofon MCA-76 for a short while, so i could use an LOMC for CD-4 in the hope of at least removing capacitance problems from the equation.. but so far they always go out of my budget.

 

[Quadro-Action]

Too much theories, too less results. After Lou's experiement also in Australia no finishing. Let's play CD-4 with our working demodulators. With well and suitable Pick ups we will have further on best results.

 

[proufo]

Too much theories, too less results. After Lou's experiement also in Australia no finishing. Let's play CD-4 with our working demodulators. With well and suitable Pick ups we will have further on best results.

That's how we felt about software decoding of matrix recordings, and see how that worked out: not just software decoding in the PC but real-time (fun!) QS and SQ high-quality decoding.

There seem to be libraries for FM demodulating, and there is a high-quality modern circuit (Dorren's) for ANRS that could be emulated in software. It's then putting the pieces together, by a capable programmer.

I think someone here is working on this.

Add to that 16rpm ripping with regular cartridges (my sloooow project) and what could be better!

 

[krkier]

...and there is a high-quality modern circuit (Dorren's) for ANRS that could be emulated in software.

How do you want to emulate a piece of hardware when you don't know what the hardware is? Lou hasn't explained this part of his decoder, and made a secret of this. -Kristian

 

[proufo]

How do you want to emulate a piece of hardware when you don't know what the hardware is? Lou hasn't explained this part of his decoder, and made a secret of this. -Kristian

I could be wrong but I think Dorren released the full circuit of his demodulator.

And anyway, the old circuits are out.

 

[proufo]

How do you want to emulate a piece of hardware when you don't know what the hardware is? Lou hasn't explained this part of his decoder, and made a secret of this. -Kristian

Here it is:

Schematic

 

[proufo]

How do you want to emulate a piece of hardware when you don't know what the hardware is? Lou hasn't explained this part of his decoder, and made a secret of this. -Kristian

And some explanations:

High Performance 2007 CD-4 Demodulator Installment IV

 

[rolvkarsten]

mightn't there be performance diminishing capacitance issues having to loop rca's in and out from turntable to pre-amp to Involve demodulator? hmm..

I expect the pre-amp to be located in front of the demodulator. For this reason the load on the cartridge will depend on the external pre-amp and the cable in between. Out from the pre-amp (RIAA) there will be line level (all if I understand this correctly) to the demod's line level input.

 

[bigbillquad]

Hi. All

I`ve had another brain wave what would be your concept CD-4 Demodulator from our friends from Involve should look like, what is your concept.
Bill...

 

[Q-Eight]

If it were possible, I'd like a display like the Technics SH-400 where you have a meter that can visually represent where the carrier signal needs to be for proper operation. Tuning by ear is OK, but having a clearly marked "Goal" helps out a lot more.

I think Mr. Dorren's version was to have two meters on the front but I don't recall if they had anything to do with carrier signal, separation or fluid level.

 

[rolvkarsten]

Lou's meter showed 30 kHz carrier level. I am pretty shure memory serves me right on this.