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

Yes! I think a Kickstarter Campaign or IndieGoGo page might be beneficial and maybe raise some awareness of this project.

If we can aim for $500 US or LESS, definitely count me in.

Hi

Back in the 70's JVC worked out how to modulate at high frequencies (above say 20 kHz) the additional information that permitted the decoding of discrete 4 channels, the system had real problems in terms of increased record wear and noisy dropouts plus the need for a special cartridge.

see:
https://en.wikipedia.org/wiki/Compatible_Discrete_4

Not sure how many CD4 recordings were made.....perhaps one of you guru's can assist?

Regards

Chucky

edisonbaggins said:

Can somebody write a brief description of what this thing will do?
Or post a link to something concise, thorough, yet understandable?

Click to expand...

Hi Circular Vibes

Its a bit of a lottery at best. Some knucklehead campaigns have walked away with wheelbarrows of cash and others get left high and dry. The problem is to manage the campaign you really need a video, someone to manage social media to push the message out to the real world. It is easy to get buried in it. To do a half arsed campaign you really need to budget a fair bit of time at at least $5k.

Its a bit like when websites started - everyone was saying "just create a website" and the customers would be forming an orderly line to your door the next day. With the exceptions of the lucky few this did not happen and in reality you need a separate advertising/ social media campaign to steer people to your site.

The next time some chump tells me "to go viral" I fear I will punch him in the head!

Not trying to be negative and perhaps someone more geeky than this old fossil can correct me

Just Sayin

Chucky

Circular Vibes said:

Chucky, would there be any benefit to putting it up on Indiegogo?

Click to expand...

I have 600 but there are a lot more
Nick Mr CD4 would know to the last one

U

chucky3042 said:

Hi

Back in the 70's JVC worked out how to modulate at high frequencies (above say 20 kHz) the additional information that permitted the decoding of discrete 4 channels, the system had real problems in terms of increased record wear and noisy dropouts plus the need for a special cartridge.

see:
https://en.wikipedia.org/wiki/Compatible_Discrete_4

Not sure how many CD4 recordings were made.....perhaps one of you guru's can assist?

Regards

Chucky

Click to expand...

Omg. Thank you got the explanation and the link. Not sure I understood it all and I have a headache, but that's not your fault!
So, the device you're trying to build helps those who have them play these CD-4 records?
I thought you all were trying to convert analog records/tapes to digital, before they wear out, or something.
So, if you're trying to build a demodulator, does that mean many or all of you don't have one already?
Or you're building a better one? Am I understanding the situation?

Hi

I suspect many CD4 decoders are getting towards the end of their life AND who knows we might even do a better Job- as Lou was attempting.

Regards

Chucky

edisonbaggins said:

U

Omg. Thank you got the explanation and the link. Not sure I understood it all and I have a headache, but that's not your fault!
So, the device you're trying to build helps those who have them play these CD-4 records?
I thought you all were trying to convert analog records/tapes to digital, before they wear out, or something.
So, if you're trying to build a demodulator, does that mean many or all of you don't have one already?
Or you're building a better one? Am I understanding the situation?

Click to expand...

Lou has told, that his new Demodulator would have a channel separation of 35 dB instead of the typical Demodulators with 30 dB. I think, that there are many fans, who have further on playing their CD-4 records direct with players and Demodulators like me. So I mean, that more orders for the new Demodulato will come . I self own 400 CD-4 records and would pay also $ 700 for a new Demodulator.

Dietrich

Quadro-Action said:

Lou has told, that his new Demodulator would have a channel separation of 35 dB instead of the typical Demodulators with 30 dB. I think, that there are many fans, who have further on playing their CD-4 records direct with players and Demodulators like me. So I mean, that more orders for the new Demodulato will come . I self own 400 CD-4 records and would pay also $ 700 for a new Demodulator.

Dietrich

Click to expand...

Actually typical early demodulators only had at best 20db separation when aligned correctly.....only much later models like the JVC's and Technics sh-400 could achieve 25db....Lou did indeed claim with his new digital hi-end filtering he could achieve 35db with much lower noise/distortion.....As great as my surround master sounds....I think Chucky could make CD-4 history and a tribute to lou.....When CD-4 is working correctly it really sounds amazing....
Mike

Hello Mike,
important for a well demodulation is a well suitable Pick up. And with my Elac MC sytems and the sharper cutting tip of van den Hul I own very well pick ups. The notes in the manual of my SH-400 says 30 dB channel separation and the indicator field in the front shows also 30 dB maximum. With my pick ups and the adjustment it shows one side 28 dB and the other 30 dB. May be, that by otherpick up combinations the separation is less. Together I own the JVC 10 S and the JVC 1000 with renewed 50 components by an engineer. The Demodulator works now also very well. But nevertheless I am interested for a new Demodulator from Australia as CD-4 freak since 1973.
In 2010 I have made the connection in Germany for the Shibata retipping of Lous test Grado sytems. Lou was very satsfied. If anybody needs a retipping, I can send him the address in Germany. Unfortunately the price for a retipping is meanwhile more expensive. In 2010 a retipping has cost € 50, now € 150! Now I am very interested, how the new Demodulator will work. And important: We have then one with new components. I have hope for a well work of Chucky and his team - like by the Involve QS/SQ Decoder.

Dietrich

Hello All

Slow progress! By my count we now have 31 starters and this translates to a cost of $672. Frustrating eh?

Actually as I have previously stated I have no commercial interest in this one, the thing that attracts me is "completing the loop" and my own perverted fascination of making a mess sound good. The CD 4 system is quite simple really but in my opinion very clever indeed- secretly I kinda like it.

I have been giving the topic some background thinking time since the start of this thread and the main problem is how to deal with the varying levels of the high frequency carrier tone and the subsequent need for level calibration to match all the cartridge output levels. You will note that the existing SM box has no provision for adjustments and so if we were to cheat and use the existing SM electronics we need to be tricky. Currently my thoughts are to use an AGC (automatic gain control) approach on this carrier to unify levels......................still thinking!

Lets hope this happens, please remember that this (if it happens) will be a background project and may take some time to complete between other priorities.

Regards

Chucky

chucky3042 said:

I have been giving the topic some background thinking time since the start of this thread and the main problem is how to deal with the varying levels of the high frequency carrier tone and the subsequent need for level calibration to match all the cartridge output levels. You will note that the existing SM box has no provision for adjustments and so if we were to cheat and use the existing SM electronics we need to be tricky. Currently my thoughts are to use an AGC (automatic gain control) approach on this carrier to unify levels......................still thinking!

Click to expand...

My uneducated guess is that a sensible approach would be to make a hybrid product, one that uses Dorren's hardware in the front end and DSP onwards.

I've been thinking about CD-4 demodulator design for 7 years since I started reading about it. I'm surprised AGC wasn't used on the carrier. What about taking it a step further with error correction via interpolation in the digital domain? Maybe borderline-playable records would have less harsh dropouts.

Good idea, will look at it.

Also the hybrid approach would involve a significant hardware development/ cost and that would push it way up again. Need to stick to existing SM box.

Regards

Chucky

quadsearcher said:

I've been thinking about CD-4 demodulator design for 7 years since I started reading about it. I'm surprised AGC wasn't used on the carrier. What about taking it a step further with error correction via interpolation in the digital domain? Maybe borderline-playable records would have less harsh dropouts.

Click to expand...

Hi. All
I was all ways after the JVC CD4-50 but every time out bided so settled for the 4DD-5.

What price did they go for?

Regards

Chucky

chucky3042 said:

What price did they go for?

Regards

Chucky

Click to expand...

I got lucky and bought my DD5 on ebay for $99. It seemed to be new in the box. The same sellet had several of them

I am seeing US$149 on ebay:
http://www.ebay.com.au/itm/221473831786?clk_rvr_id=889586725450&rmvSB=true

Makes me think we really need to hit the US $500 mark or it will not be worth it

chucky3042 said:

Need to stick to existing SM box.

Click to expand...

You can use two boxes, one for the analog circuitry and the other for DSP.

I'd be in for the DSP box if it allows the input of a digital disc player, using specially prepped discs.

The existing SM is part analogue/ part DSP. To hit a reasonable development cost target we really need to keep all the work in the DSP.

Regards

Chucky

proufo said:

You can use two boxes, one for the analog circuitry and the other for DSP.

I'd be in for the DSP box if it allows the input of a digital disc player, using specially prepped discs.

Click to expand...

You're right about price Chucky, except that for us quad lunatics, a brand new, well performing, modern (not going to need parts replacement for 20-30 years)
demodulator is well worth it.

"...the main problem is how to deal with the varying levels of the high frequency carrier tone and the subsequent need for level calibration to match all the
cartridge output levels. You will note that the existing SM box has no provision for adjustments and so if we were to cheat and use the existing SM electronics
we need to be tricky. Currently my thoughts are to use an AGC (automatic gain control) approach on this carrier to unify levels..." -- I assume with this, that
you're talking about digital carrier level and separation adjustments? I was wondering about that, if in today's era automatic carrier lock could be reliably
realized, but figured manual separation controls would still be compulsory.

Funny story Bob. I managed to pick up a 4DD-5 and 4MD-20X and spare stylus, all New Old Stock, from a seller in Canada clearing out his late father's old
inventory from a Hi-Fi store, about three years ago I think. He had a lot of them at the time, and I got them at reasonable prices for NOS. As he cleared out
his inventory I think he raised his prices a bit. I was quite giddy when I got it, opening the box for possibly the first time since it was packaged, to the new
electronics smell, and knowing that the demodulator is older than I am - and I'm now the first owner!

This auction visually looks similar to those auctions, but definitely not by price (awfully expensive):

http://www.ebay.com.au/itm/JVC-CD-4...-NEW-in-BOX-/311338458900?hash=item487d37df14