CD-4 - The thin line between success and failure, but still in the fight!

[Doug G.]

Once a technology gets beyond the typical competence level of the average human being, that technology is more likely to fail with the general public because they lose patience, with themselves, mainly.

Doug

 

[fredblue]

who did you say created this chamber of torture and horrors Freddie, and remind me why we are so crazy for it please?

i would add that i feel things have moved on over the years and superb conversions by people like AOQ, Cai, etc set the standard of what to try and achieve with CD-4.

i've never come up with anything approaching their work and probably never will but its been something to strive for.

there was a time i had one cherished (and i now realise, fairly half-assed) CD-4 conversion of AWB.. fast forward 15 years and i've now heard several more stabs at it, including a couple of really great conversions and thanks to the kindness of edisonbaggins gifting me 37 copies of the album i hope one day to do a demodulated transfer of my own that i can truly enjoy rather than wince at its deficienciesssss...!!

 

[fredblue]

Once a technology gets beyond the typical competence level of the average human being, that technology is more likely to fail with the general public because they lose patience, with themselves, mainly.

Doug

this should've been JVC's marketing tagline all along!

"CD-4, its not 4 every 1"

i'll get me coat..

 

[fredblue]

Yup. However they also had rude nick names for QS/SQ that wasn't so tricky to set up.

At one point in the mid 70's I had a roommate that worked for a large audio distributor, Throckmorton. My roommate Tip enjoyed company on road trips so I went to. Occasionally he would schmooze at home with a client. I met a lot of Hi-Fi store owners & their staff. Not one of them had a quad set up of their own. And if they visited our place you could tell it was all they could do to conceal their scorn at my Kenwood 9940 & 4 speaker set up.

However I bet most of them are dead or at least out of business. Mean while I'm still rockin' out to quad & indeed as others have said here, I feel like I am in the second golden age of surround sound. I have the last laugh.

yeah! balls to them all!

lets hear it for Sonik Wiz still alive and well and rockin' in the free world after all these years

 

[Sonik Wiz]

heresy!! they shoulda had their mouths washed out with carbolic soap!!

Haha indeed! What is carbolic soap? Must be a UK thing. Me mum always used Ivory Soap if I said something other than Fuuudge.

 

[kfbkfb]

Checking the Q/CD-4 cart listings in Audio mag (separate thread), the ADC Q/CD-4 cart is the S XLM MK 2, the ADC ZLM isn't listed as a Q/CD-4 cart (1976 Audio mag guide).

Some comments about the ADC S XLM MK 2:
https://audiokarma.org/forums/index.php?threads/adc-super-xlm-mk-ii-how-does-it-sound.919992/
A test report:
https://worldradiohistory.com/Archi...idelity/70s/High-Fidelity-1975-10.pdf#page=55
(I recommend getting a Audio Technica CD-4 cart)


Kirk Bayne

 

[Quad Linda]

As I recall, ADC ZLM was sold in '76. The fact it's not on that list speaks volumes as to it's suitability.

I subscribed to Audio mag in 76. They were often on the money.

 

[jupp369]

Don't forget the vertical alignment!
I don't have the sandpaper anymore!
1970 was the time when they changed the vertical angle of the needles.
I cut a few soft mats (1mm) that I can put on with or without the thick rubber mat and thus vary the height.
I also adjusted the tangential tracking error angle for the LP's. CD-4 discs are recorded up to a maximum of 8 cm from the outer edge. However, the nominal overhang refers to an optimum for LPs and singles. (With the good CD-4 system I will definitely not play any old 45s!)
The "Schön Schablone" is very helpful, you can also quickly make it yourself.

 

[fredblue]

Don't forget the vertical alignment!
I don't have the sandpaper anymore!
1970 was the time when they changed the vertical angle of the needles.
I cut a few soft mats (1mm) that I can put on with or without the thick rubber mat and thus vary the height.
I also adjusted the tangential tracking error angle for the LP's. CD-4 discs are recorded up to a maximum of 8 cm from the outer edge. However, the nominal overhang refers to an optimum for LPs and singles. (With the good CD-4 system I will definitely not play any old 45s!)
The "Schön Schablone" is very helpful, you can also quickly make it yourself.

very interesting..! i definitely found differences between my AT15S and AT15Sa, which were released right in the middle of the SRA change from 15 to 20 degrees (15S requires 15, 15Sa requires 20) and that the 15S seemingly ran heavier than the 15Sa and the 15S was fussier than the 15Sa and ultimately had much better results with the 15Sa.

is that 8cm from the run-in groove? that feels kinda low, pretty sure some of the RCA and Warner discs go beyond that? or 8cm from the end of the run-out (i.e. 8cm from the label)?

 

[MidiMagic]

The sandpaper effect is white noise that sounds like the continuous rubbing of sandpaper on wood (with no back and forth motion pauses).

If any dust is in the grooves, it sounds like hundreds of people breaking pencils in half.

 

[Gimme 4]

I subscribed to Audio mag in 76. They were often on the money.

Ah yes. Audio magazine. I bought Koss Pro 4a headphones in Aug 1969. In the box was a card for 3 months of free Audio magazine. Somehow that got entered as 3 YEARS! I kept the sub going until 1992 I think it was. Still have them all in "banker's boxes" filed away.

 

[kfbkfb]

Just an FYI - the stylus overhang adjustment and VTA adjustment are the 2 required adjustments for playback of all records, CD-4 just made setting the overhang & VTA correctly more important (stereo/mono 45s/LPs will play with these adjustments a little "off" [just some increased distortion, which gets worse toward the paper disc label]).

edit: of course, anti-skating also.


Kirk Bayne

 

[J. PUPSTER]

Just an FYI - the stylus overhang adjustment and VTA adjustment are the 2 required adjustments for playback of all records, CD-4 just made setting the overhang & VTA correctly more important (stereo/mono 45s/LPs will play with these adjustments a little "off" [just some increased distortion, which gets worse toward the paper disc label]).


Kirk Bayne

Here's some required reading for VTA, and a big thanks Kirk, for that pspatialaudio link

https://www.quadraphonicquad.com/fo...-angle-setup-on-turntables.29642/#post-536088
Thread was created in the Stereo area, but hey I'm far from perfect here

 

[Doug G.]

As I recall, ADC ZLM was sold in '76. The fact it's not on that list speaks volumes as to it's suitability.

I subscribed to Audio mag in 76. They were often on the money.

Audio was my favorite of all the magazines, back then. It was the most technical, which is more me.

Doug

 

[Doug G.]

Sandpaper distortion is actually the carrier detection circuit switching on and off as it gains and loses the carriers in rapid succession. It is not a function of that actual noise coming from the groove. It is a function of the demodulation process if it's not going right.

The "breaking pencils" or "explosions" aspect only happens if the CD-4 system is not set up correctly. Scratches or dirt sound no different from two channel records in my system. As I have stated elsewhere, I have heard the various CD-4 distortions and actually did have some of them in my system when I re-entered the CD-4 world many years ago, now, but they were corrected, mainly through tracking adjustments.

Doug

 

[J. PUPSTER]

Sandpaper distortion is actually the carrier detection circuit switching on and off as it gains and loses the carriers in rapid succession. It is not a function of that actual noise coming from the groove. It is a function of the demodulation process if it's not going right.

The "breaking pencils" or "explosions" aspect only happens if the CD-4 system is not set up correctly. Scratches or dirt sound no different from two channel records in my system. As I have stated elsewhere, I have heard the various CD-4 distortions and actually did have some of them in my system when I re-entered the CD-4 world many years ago, now, but they were corrected, mainly through tracking adjustments.

Doug

I've got one particular LP (forget the name off hand) that had sandpaper at a particular spot on a couple of songs. I had planned at some point of making adjustments to VTA on those spots to see if it could be corrected. However, I have not tried it with my new Marantz CD-400B, I had used the QRX-8001 and maybe it wasn't adjusted for optimal performance, what do you think Doug?

 

[Sonik Wiz]

I've got one particular LP (forget the name off hand) that had sandpaper at a particular spot on a couple of songs. I had planned at some point of making adjustments to VTA on those spots to see if it could be corrected. However, I have not tried it with my new Marantz CD-400B, I had used the QRX-8001 and maybe it wasn't adjusted for optimal performance, what do you think Doug?

I'm thinkin' the album was Rock and Drums:
https://www.ebay.com/itm/203003853598
It will be interesting to hear your comments when trying it on the 400B. Per @Doug G. the sandpaper sound comes from the carrier detection circuit switching on and off. Since the 400B has automatic carrier adjustment it might help it. This works real time & I like the way it is implemented in that unit. Much like an AGC circuit and using an FET for the gain control. Really the Marantz 400B is a big step up from the earlier 400.

 

[J. PUPSTER]

I'm thinkin' the album was Rock and Drums:
https://www.ebay.com/itm/203003853598
It will be interesting to hear your comments when trying it on the 400B. Per @Doug G. the sandpaper sound comes from the carrier detection circuit switching on and off. Since the 400B has automatic carrier adjustment it might help it. This works real time & I like the way it is implemented in that unit. Much like an AGC circuit and using an FET for the gain control. Really the Marantz 400B is a big step up from the earlier 400.

I think you're right about the album there SW, pretty sure I didn't spend that much on it though

 

[Doug G.]

I've got one particular LP (forget the name off hand) that had sandpaper at a particular spot on a couple of songs. I had planned at some point of making adjustments to VTA on those spots to see if it could be corrected. However, I have not tried it with my new Marantz CD-400B, I had used the QRX-8001 and maybe it wasn't adjusted for optimal performance, what do you think Doug?

Sometimes, it can be the record, especially if the sandpaper happens consistently in the same spot(s). The carriers may be worn or weren't pressed well, to begin with. I would say it would be more likely to be other than the record if the sandpaper happens more randomly.

I have one record (forget which one, now) that "splats" in the same spot every time I play it and I did decide it's the record (I bought it used) because it's so consistent and I rarely ever get sandpaper with any other record.

Doug

 

[Sonik Wiz]

Many years ago I initiated a regular column at Larry Clifton's MCS Review called DIY. It was about home built gear to further advance one's interest in audio & specifically quad. Also @par4ken was a notable contributor to the column. The first article was how to build a power supply for other projects I had planned. Well, back then, if you couldn't buy it, you built it.

Taking an afternoons break from the forum I had a bit of an epiphany realized from this CD-4 thread: just about every damn thing about high quality home audio is DIY!

You do it your self when experimenting with best cables, room acoustics, setting up a turntable. You do it your self when ripping all that media to a NAS or whatever that you also set up your self. It's DIY when you take a stereo track & say, hmmm, how can I upmix this?

But it seems that CD-4 is the most DIY you can do without picking up a soldering gun. You're on your own making decisions about phono cart, turntable. Sure maybe there's some help from others but eventually it's back in someones hands making the most out of set up, adjustments, picking the best demodulator you can find & adjusting. And the most DIY of all with CD-4 is tracking down gremlins that defy explanation.

Some how I feel very good about this. In the bigger picture it's wonderful to have a passion that stimulates the mind, the hands, & our sense of achievement when we've finally made something work well.