Philip Spinner
1K Club - QQ Shooting Star
Yes setting the anti skating and weight the same works in a perfect world but I think if your TT is not perfectly level then that system may not be the best. A flat, smooth disc will never lie.
JVC (Victor) CD4-1 CD-4 Demodulator. Anybody have any experience with it?
- Thread starter Q-Eight
- Start date
Help Support QuadraphonicQuad:
Brilliant! :upthumb
Is the antiskate setting so much more important to CD-4 because the stylus has to much more accurately track the ultra high frequency nature of the microgrooves that just mistrack in a way that's not detectable with regular LPs?
I mean, since going with the AT cart I don't have anywhere near as many inner groove distortion problems (unless the records got trashed by the previous owner or I suspect in one or two cases they're just duff pressings in the first place) relative to my conical and elliptical styluses (styli..?
) IGD is seriously lessened so I would have thought that was indicative of the antiskate being ok.. but it seems with CD-4 ok is not good enough.. everything needs to be perfect, the stars need to align.. Jupiter needs to be in Uranus and next July we collide with Mars.. and then a speck of cosmic dust stuck in the vinyl's grooves comes along "thwack" like St Judy's Comet and Thuds Me Like A Rock..! :ugham:
Last edited:
Philip Spinner
1K Club - QQ Shooting Star
I would think proper anti skating is critical for all records, especially cd-4. To be honest though when I purchased my demodulator back in the 70's I hooked it up, plugged it in and after 5 minutes of tweaking I had perfect quad. Of course everything was brand new back then. I suspect there is still something not quite right with yours. I wish I could be more help. It's been over 30 years since I used my demodulator and I would not be surprised if it does not work anymore. What I'm waiting for is the new super cd-4 from our friends from down under. I will be purchasing that as soon as it's available.
Funny you mentioned space debris. I saw something fall from the sky about 10:30 EDT last night from my train window. Did anyone else see it. It looked like space debris as it had an orange glow with a very long trail.
Funny you mentioned space debris. I saw something fall from the sky about 10:30 EDT last night from my train window. Did anyone else see it. It looked like space debris as it had an orange glow with a very long trail.
I now was able to obtain a schematic and some info from a trusted source.
The CD4-1 was designed before the PLL design was figured out. It uses "envelope detection" for the carrier, rather than a PLL. The adjustment on the back is not for 30Khz level, but instead for "muting" level. The CD4-1's design uses a method entirely different than the later PLL models. When you adjust the muting control, the unit is demodulating with no change in sound or separation, up to a point when it suddenly "mutes" and goes to stereo. It's just like the muting threshold control on a FM Stereo tuner. Entirely different than the 30Khz carrier control that you adjust for clean recovery of the test tone. I do not know what record JVC supplied to adjust the muting control, that's a mystery.
So, the final word is that the CD4-1 is a curiosity, a museum piece, of the 1st generation design prior to PLL. The CD4-10 and 4DD-5 is entirely different, and superior.
You can compare the attached schematic to the CD4-10 or 4DD-5 schematics that are ready available on this forum.
The CD4-1 was designed before the PLL design was figured out. It uses "envelope detection" for the carrier, rather than a PLL. The adjustment on the back is not for 30Khz level, but instead for "muting" level. The CD4-1's design uses a method entirely different than the later PLL models. When you adjust the muting control, the unit is demodulating with no change in sound or separation, up to a point when it suddenly "mutes" and goes to stereo. It's just like the muting threshold control on a FM Stereo tuner. Entirely different than the 30Khz carrier control that you adjust for clean recovery of the test tone. I do not know what record JVC supplied to adjust the muting control, that's a mystery.
So, the final word is that the CD4-1 is a curiosity, a museum piece, of the 1st generation design prior to PLL. The CD4-10 and 4DD-5 is entirely different, and superior.
You can compare the attached schematic to the CD4-10 or 4DD-5 schematics that are ready available on this forum.
Attachments
From a cd-4 equipment guru
[FONT="]! I have accumulated and studied the JVC CD4-1 (two versions now), CD4-2, CD4-10, CD4-20, CD4-30 (4DD-5 in the US). Along with a couple of different Technics and Toshiba models. Still haven’t gotten ahold of a CD4-50 yet, but it’s just a matter of time I hope. So far my favorite is now the CD4-1 (non-IC) original demodulator. This unit has a good phono-preamp, and really sounds natural and “airy”……..while just slightly less capable in the actual separation compared to the IC based demodulators that came later. I’d love to compare that original CD4-1 to the studio version CD4-1000 that as far as I know only Ron Brain and Nick Perragini have. Externally, they look almost the same………so I’m hoping to some day get some pictures of the inside of the CD4-1000 that I can compare to the board layout in the CD4-1. I think they’ll be very similar.[/FONT]
[FONT="]! I have accumulated and studied the JVC CD4-1 (two versions now), CD4-2, CD4-10, CD4-20, CD4-30 (4DD-5 in the US). Along with a couple of different Technics and Toshiba models. Still haven’t gotten ahold of a CD4-50 yet, but it’s just a matter of time I hope. So far my favorite is now the CD4-1 (non-IC) original demodulator. This unit has a good phono-preamp, and really sounds natural and “airy”……..while just slightly less capable in the actual separation compared to the IC based demodulators that came later. I’d love to compare that original CD4-1 to the studio version CD4-1000 that as far as I know only Ron Brain and Nick Perragini have. Externally, they look almost the same………so I’m hoping to some day get some pictures of the inside of the CD4-1000 that I can compare to the board layout in the CD4-1. I think they’ll be very similar.[/FONT]
I am going to sell my cd4-50 and i have 2. One has an issue with something other than the chip, just have not figured it out yet, and if anyone could come up with a schematic for a cd4-50 it would help, no one has ever seen one. So if someone wants to take a chance on that one i will take offers, but i will also take offers on the the cd4-50 which works, which is a wonderful unit. Best unit ever made other than the cd41000. It has been reworked to exceed specs. All this old equipment needs special care to survive and sound even better that it originally was made. If anyone is interested in the cd4-50 give me a reasonable bid. Not sure if i should ebay it or get it to a quadfellow here, but cash would certainly be a motivating factor in getting it boxed.
In fact i have been watching these comparisons with a bit of amusement, as rooms, equipment and speakers all vary which can influence sound. The other item that can change it, is if equipment has been upgraded. I was chatting when this came back.
[FONT="] I have an SQ model Surround Master myself. And, I’ve done extensive testing comparing it to the QSD-1, QSD-1000, Tate II and Space & Image Composer. Right off, I would say anyone else trying to compare would be deceived if their original quad decoder isn’t restored. The Surround Master will blow them away just for “sound quality” and frequency response range. However, if the original quad decoder is restored………that comparison becomes a non-issue. Then it’s just about separation and directional steering. And, that’s where the Surround Master whether with QS versus the Sansui’s or SQ versus the Fosgate units (TATE II/S&IC) comes in 2[SUP]nd[/SUP] place against any of them. For SQ, I still go the restored S&IC as my primary decoder, and for QS it’s the QSD-1000. And, what the masses may not understand is that I am in NO WAY slamming the Surround Master! It’s an awesome unit, and for $500 gives you without a doubt the “next best” decoder to any of the QS or SQ pinnacle units. And, it’s performance is no doubt VERY close…….but better? No way. For those that don’t already own one of the top 4 decoders……..it really makes more sense to buy a Surround Master than invest in restoring one of the original decoders. BUT, for no compromise absolute best decoding in either format………the Sansui’s and Tate/S&IC still haven’t been bested. I actually use my Surround Master frequently…………..whenever I want to decode to 5.1…….I’ll use it! And, it’s my primary decoder for stereo TV & movies that I stream to get a decent 5.1 presentation. But, if I’m listening to QS or SQ encoded ……….then it’s my original decoders for sure!
[/FONT]
In fact i have been watching these comparisons with a bit of amusement, as rooms, equipment and speakers all vary which can influence sound. The other item that can change it, is if equipment has been upgraded. I was chatting when this came back.
[FONT="] I have an SQ model Surround Master myself. And, I’ve done extensive testing comparing it to the QSD-1, QSD-1000, Tate II and Space & Image Composer. Right off, I would say anyone else trying to compare would be deceived if their original quad decoder isn’t restored. The Surround Master will blow them away just for “sound quality” and frequency response range. However, if the original quad decoder is restored………that comparison becomes a non-issue. Then it’s just about separation and directional steering. And, that’s where the Surround Master whether with QS versus the Sansui’s or SQ versus the Fosgate units (TATE II/S&IC) comes in 2[SUP]nd[/SUP] place against any of them. For SQ, I still go the restored S&IC as my primary decoder, and for QS it’s the QSD-1000. And, what the masses may not understand is that I am in NO WAY slamming the Surround Master! It’s an awesome unit, and for $500 gives you without a doubt the “next best” decoder to any of the QS or SQ pinnacle units. And, it’s performance is no doubt VERY close…….but better? No way. For those that don’t already own one of the top 4 decoders……..it really makes more sense to buy a Surround Master than invest in restoring one of the original decoders. BUT, for no compromise absolute best decoding in either format………the Sansui’s and Tate/S&IC still haven’t been bested. I actually use my Surround Master frequently…………..whenever I want to decode to 5.1…….I’ll use it! And, it’s my primary decoder for stereo TV & movies that I stream to get a decent 5.1 presentation. But, if I’m listening to QS or SQ encoded ……….then it’s my original decoders for sure!
[/FONT]
Brilliant summation of it all imho thanks for popping in and posting here! :upthumb
fwiw I have found exactly the same as you wrt the Surround Master and SQ, it is largely very good indeed but not quite the best (it is the lack of cancellation of all front to back bled vocals with the SQ vinyl Surround Master that is for me its main achilles heel.. as I said before on here, not in a pretentious way but the Surround Master has a lovely "musicality" to what it does, slightly less clinical/synthetic than a Tate, while not as accurate.. and then there's those pesky ghost vocals in the rears with SQ that the Tate just plain handles better.
ah well.. as you so rightfully say, the Surround Master is quite an achievement any which way you look at it.. an excellent QS and very very good SQ decoder in 2014 (or whenever it first came out!?) really is rather extraordinary and something to very much applaud and be thankful to Involve for all their hard work.. something that I imagine they never made a penny out of to this day!
fwiw I have found exactly the same as you wrt the Surround Master and SQ, it is largely very good indeed but not quite the best (it is the lack of cancellation of all front to back bled vocals with the SQ vinyl Surround Master that is for me its main achilles heel.. as I said before on here, not in a pretentious way but the Surround Master has a lovely "musicality" to what it does, slightly less clinical/synthetic than a Tate, while not as accurate.. and then there's those pesky ghost vocals in the rears with SQ that the Tate just plain handles better.
ah well.. as you so rightfully say, the Surround Master is quite an achievement any which way you look at it.. an excellent QS and very very good SQ decoder in 2014 (or whenever it first came out!?) really is rather extraordinary and something to very much applaud and be thankful to Involve for all their hard work.. something that I imagine they never made a penny out of to this day!
Attached is a partial schematic of the CD4-50. The missing part is the schematic of the daughter card, TDM-27, which contains the CD4-392 carrier recovery circuits. Looking at the schematic you will notice several design details that make it a better unit. 1st, there are diff-amps in the phono preamp and ARNS circuits. The power supply is improved and is bipolar (Puts out + and- voltages). The phono preamp, intermediate stage and output buffers are all bipolar designs. This unit is the inspiration for one of my CD4 projects. Take a CD4-392 based carrier recovery design (in this case a F-2589 assembly from a Sansui receiver) and marry it with the ARNS and modified matrix circuits of a 4DD-5. Change and upgrade the power supply to a bipolar design. Put in a OPA2134 based phono preamp and output buffers. The project is about ready for debug and testing.
Also attached is the User manual and a Japanese service manual.
Also attached is the User manual and a Japanese service manual.
Similar threads
