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

chucky3042 said:

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

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I'm just one person, but I'd be in for the higher price. $172 is a really nice meal (or a couple "regular" ones) out with the wife.

I'm guessing that you folks at Involve haven't messed much with vintage CD4 gear. It can be very tweaky and frustrating. Those of us with substantial CD4 collections (I have 50+) would be thrilled with a better solution.

We've heard what CD4 can offer during those blissful moments when everything is dialed in properly. We've also heard that annoying raspy distortion popping up in left rear towards the end of a side, seemingly out of nowhere. A lot of it is hardware dependent -- proper cartridge, stylus, setup, low impedance cables (more important than I realized at first). But what would be great is a demodulator that sounded great and wasn't so GD picky about everything.

If you guys can deliver, that's awesome and easily worth $672 for me. If you can't, I still appreciate the fact that you considered it.

Chucky,
if there is no reason for you to this right away, i believe it will take a while to get the Germans and others not connected to a board to get word and show interest. Perhaps put a date, october perhaps, before the holidays here, and gather all the fans to the project. It takes time to get the word out even with the net, and sometimes time to think about finances before leaping.

The one`s that I was bidding on a couple of years ago one went for $259us & another went for $360us to rich for me at the time so I managed to buy a 4DD-5 for $60us.Funny a week latter I bought 2 of them, on Trademe that`s like a small version of Ebay that's run here in New Zealand $40.00 nz so I have three of them now. I have also about 300 CD-4 LP`S
I have a few spare CD-4 test disc if you need one for testing you can have one of them chucky any time.
Bill....

chucky3042 said:

What price did they go for?

Regards

Chucky

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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.

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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.

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A CD-4 demodulator is a much more complex device than a matrix decoder. It might not be sensible/feasible to go from the cartridge output directly to an ADC.

I believe this may work:

1) An analog module that can be used as a decent regular phono section.

2) Four outputs from the analog module, two AM and two FM (plus the regular 20-20kHz phono output).

3) A DSP module with four inputs. Input level controls in the AM inputs to match the FM decoded signal.

Wishful thinking: a digital input in the DSP module, that would receive the output of a digital disc player playing processed rips of CD-4 records. Just one A/D conversion is way more elegant than two.

Hi Proufo

Your comments are all good but the original assumption is wrong. In fact the SM is WAY more complicated (in terms of software) than a CD4 demodulator, probably by a factor of 20. We have heaps of room to do all sorts of tricky stuff, in software typically if you can think it/ you can do it.

Regards

Chucky

One way to demodulate the CD-4 carriers:

Use an analog circuit - hard limiting combined with a PLL demodulator
(IIRC, this was invented by Lou Dorren, the patent may be available
online).

A possible CD-4 demodulator:
(analog) phono input
output split
base/sum signals processed with (analog or digital) RIAA EQ
(digital) bandpass filters
(analog) hard limiter/PLL for demodulation of the carriers
(digital) difference signal EQ and ANRS decoding
(analog or digital) sum/difference processing to get LF,LB,RF,RB

Kirk Bayne

Dear discrete desperado's

We have had a few "external" guinea pigs. Currently the tally is 34 starters. This represents a cost of US$644

Tedious but getting there......really starting to think about it now.

Regards

Chucky

Dear discrete desperado's

We have had a few "external" guinea pigs. Currently the tally is 34 starters. This represents a cost of US$644

Tedious but getting there......really starting to think about it now.

Regards

Chucky

Err

Actually if we crack say $600 I will start as I know more will follow as word gets around.

Yours in foolishness

Chucky

For me is $ 600 OK. But it is astonishing, that we have in this forum hardly or no Fans from Japan, although this forum may worldwide the only one and some european Fans are also members. If here is nevertheless a japanese Fan member,then he may try to find a japanese forum about Quadraphony and Surround. Also in Japan or even specially (JVC) should excist some quad-fans. Then he could there write a message about the possibility to get a new Demodulator and we or better Chucky has new or further orders.

Dietrich

hello chucky

count me in
norman kern

quady.de

I have now written to the japanese HiFi-Forum [email protected] that they may inform their members,that we have now the possibility to get a new CD-4 Demodulator and the japanese fans can inform or may do an order in the QQforum. We will see,if there is any response or echo. In our german HiFi-Forum are named some asia hifi-forums.

Dietrich

This might be useful at development time:

Reverse RIAA

Any chance of someone pressing new CD-4 records, including new versions of CD-4 albums made before?

scifi said:

Any chance of someone pressing new CD-4 records, including new versions of CD-4 albums made before

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I believe Lou said all the CD4 mastering equipment was gone long ago. I figure if he says its gone, no one has it any more.

Actual we have the DVD-Audio and the SA-CD with best channel separation and HiFi. Why those dreams of new CD-4 record pressings? But on the other hand is such an attempt to produce a new CD-4 Demodulator very important and wellcome. Then we could listen our excisting CD-4 records with often phantasic surround-music in best suitable quality. I wonder, that we have actual only 30 orders (?), although for the Dorren-Demodulator it has been around 150. Where are now this fans with a new order actual?

Dietrich

Some of the people who were originally interested in the Dorren demodulator may have passed away (we've lost a few QQ'ers in recent years), or drifted away from the hobby. And there's still the matter of getting the word around so that other hobbyists can put their names on the list. Thanks for helping in Germany.

Lou did have an assistant who compiled a list of potential buyers. I wonder if Jon could put them in touch with Chucky? As to why have a new CD4 record? Some of us don't like digital and even with the lack of extreme high end, you can get a bit more bass on record than in digital form. I agree that records are technically more likely to faults and drawbacks, but it is still LP that I fall back on for entertainment. I don't know why for sure, but I think it must be a feeling I get that digital can't provide. I would not have digital in my sound system at all if it weren't for a smokin' hot deal on a second hand Oppo from a QQ member. The Oppo has shifted my mind set considerably.

Record fanatics
https://www.quadraphonicquad.com/fo...-The-record-pressing-machines-are-wearing-out

Count me in please.