I propose the line input should be four-channel and perhaps six-channel.
Several multi-channel line inputs would be much, much better.
Lou Dorren: A new CD-4 Demodulator!!! [ARCHIVE]
- Thread starter loudorren
- Start date
Help Support QuadraphonicQuad:
Several multi-channel line inputs would be much, much better.
loudorren
Well-known Member
Hello CD-4 Bunch,
JD Mack,
The wide.band input and output are for users who wish to experiment with digitizing the CD-4 composite signals for archive digital recording and playback.
The frequency response will be DC to 70 KHz with a 1 VAC RMS level(preliminary specifcation, subject to change).
Quadro-Action, Thanks Dietrich
kfbkfb,
Kirk, I don't know who reported the carrier drop, but it does not agree with the data that I took with 100 play, 200 play, 300 play, 400 play, and 500 play with conical, elliptical and Shibata stylus. With the conical tip, the tests included 2.5 gram and 4 gram tracking pressures. Elliptic and Shibata tips were at 1.5 grams tracking pressure. All tests were measured before and after cleaning with QSI cleaner and were done with a Shibata stylus. The test disk was set up to have spot frequencies from 50 HZ to 50KHz. One track with and one track without 30 KHz carrier. The next track followed with modulated carrier at maximum modulation index (DR). The next track was random undulated 2 channel audio (music)and the following track was undulated CD-4 audio (music). 10 disks for each test were made and 2 of each of those disks were used as view test samples for the electron microscope.
The result was that even with trough damage by the 4 gram conical stylus, when played back with the Shibata stylus there was no significant signal reduction in any of the tracks (less than .5 dB)including the CD-4 carriers.
Disk compound was Q-540.
aludra, Quadro-Klaus, My pleasure.
Q-Eight, Carrier level has no effect on the separation in CD-4 and separation adjust has no effect on carrier level either.
The Quadfather, Correct!!! You have just passed the Edwin H. Armstrong Course on FM receivers.
proufo, That Job is for an AV control center. This is a CD-4 demodulator with with inputs and outputs for external archive digitizing.
Lou Dorren
JD Mack,
The wide.band input and output are for users who wish to experiment with digitizing the CD-4 composite signals for archive digital recording and playback.
The frequency response will be DC to 70 KHz with a 1 VAC RMS level(preliminary specifcation, subject to change).
Quadro-Action, Thanks Dietrich
kfbkfb,
Kirk, I don't know who reported the carrier drop, but it does not agree with the data that I took with 100 play, 200 play, 300 play, 400 play, and 500 play with conical, elliptical and Shibata stylus. With the conical tip, the tests included 2.5 gram and 4 gram tracking pressures. Elliptic and Shibata tips were at 1.5 grams tracking pressure. All tests were measured before and after cleaning with QSI cleaner and were done with a Shibata stylus. The test disk was set up to have spot frequencies from 50 HZ to 50KHz. One track with and one track without 30 KHz carrier. The next track followed with modulated carrier at maximum modulation index (DR). The next track was random undulated 2 channel audio (music)and the following track was undulated CD-4 audio (music). 10 disks for each test were made and 2 of each of those disks were used as view test samples for the electron microscope.
The result was that even with trough damage by the 4 gram conical stylus, when played back with the Shibata stylus there was no significant signal reduction in any of the tracks (less than .5 dB)including the CD-4 carriers.
Disk compound was Q-540.
aludra, Quadro-Klaus, My pleasure.
Q-Eight, Carrier level has no effect on the separation in CD-4 and separation adjust has no effect on carrier level either.
The Quadfather, Correct!!! You have just passed the Edwin H. Armstrong Course on FM receivers.
proufo, That Job is for an AV control center. This is a CD-4 demodulator with with inputs and outputs for external archive digitizing.
Lou Dorren
Regarding (100 play) CD-4 Carrier Level:
Quoting an article in the 1973-08 Popular Electronics:
The records available at the time were the first three
"Quadradisc" releases from RCA and three JVC discs
(Using a Technics 460-C at 2 grams)
We monitored the change in carrier level at the output
from the cartridge during 100 successive plays of a
portion of one of the Quadradiscs. After 100 plays, the
level of the carrier was fluctuating slightly, down by
3dB at times.
I don't know what kind of vinyl RCA was using for the
first Quadradiscs (I believe this article is much the same
as article in the 1972-12 Stereo Review, so that implies
the RCA Quadradiscs were made in 1972).
Kirk Bayne
Quoting an article in the 1973-08 Popular Electronics:
The records available at the time were the first three
"Quadradisc" releases from RCA and three JVC discs
(Using a Technics 460-C at 2 grams)
We monitored the change in carrier level at the output
from the cartridge during 100 successive plays of a
portion of one of the Quadradiscs. After 100 plays, the
level of the carrier was fluctuating slightly, down by
3dB at times.
I don't know what kind of vinyl RCA was using for the
first Quadradiscs (I believe this article is much the same
as article in the 1972-12 Stereo Review, so that implies
the RCA Quadradiscs were made in 1972).
Kirk Bayne
loudorren
Well-known Member
Hello Quadies,
kfbkfb,
Kirk, That variation was "Carrier Recovery Amplitude Perturbations" because they did not clean the disk. Even Q-540 could get dirty. There is some introduced carrier level change during mastering by the carrier level control in the encoder but this is only active during loud passages of the main channel. Carrier level variations such as these will have no effect on the performance of a demodulator with a QSI5022 or the new demodulator I have designed because of the high gain 30 KHz limiter.
Lou Dorren
kfbkfb,
Kirk, That variation was "Carrier Recovery Amplitude Perturbations" because they did not clean the disk. Even Q-540 could get dirty. There is some introduced carrier level change during mastering by the carrier level control in the encoder but this is only active during loud passages of the main channel. Carrier level variations such as these will have no effect on the performance of a demodulator with a QSI5022 or the new demodulator I have designed because of the high gain 30 KHz limiter.
Lou Dorren
Hey Lou,
I've been staying out of the discussion since it has largely been of a technical nature, and when it comes to the nitty-gritty of electronics, I'm not a very technical guy.
However, seeing the drawings of the front and back panels has me super-excited about this project! I can't wait! Thanks for your continued efforts and for making this project a collaberative effort. You're going to make a bunch of quadheads very, very happy!
Cai
I've been staying out of the discussion since it has largely been of a technical nature, and when it comes to the nitty-gritty of electronics, I'm not a very technical guy.
However, seeing the drawings of the front and back panels has me super-excited about this project! I can't wait! Thanks for your continued efforts and for making this project a collaberative effort. You're going to make a bunch of quadheads very, very happy!
Cai
Regarding CD-4 Vinyl:
Quoting an article by Stephen Traiman
(probably in a Summer 1974 Billboard):
A candid acknowledgement by RCA and other
key recording companies that there was a
problem with "soft" CD-4 disks, a problem
they now feel is just about licked with a
commitment to a heavier 110-gram vinyl mix.
Was there ever any sort of accounting of
which CD-4 discs were "soft" (vinyl)?
Checking the 1972-12 Stereo Review CD-4
evaluation article, RCA APD1-0001 was used
for the 100 successive play carrier test,
with the same 3dB drop reported. (perhaps
RCA APD1-0001 was one of the "soft" discs)
The Stereo Review article also states that
the ADC XLM, Empire 1000ZE/X, Shure V-15
Type II (Improved) performed as well as the
Panasonic 450-C with the Panasonic SE-405.
Kirk Bayne
Quoting an article by Stephen Traiman
(probably in a Summer 1974 Billboard):
A candid acknowledgement by RCA and other
key recording companies that there was a
problem with "soft" CD-4 disks, a problem
they now feel is just about licked with a
commitment to a heavier 110-gram vinyl mix.
Was there ever any sort of accounting of
which CD-4 discs were "soft" (vinyl)?
Checking the 1972-12 Stereo Review CD-4
evaluation article, RCA APD1-0001 was used
for the 100 successive play carrier test,
with the same 3dB drop reported. (perhaps
RCA APD1-0001 was one of the "soft" discs)
The Stereo Review article also states that
the ADC XLM, Empire 1000ZE/X, Shure V-15
Type II (Improved) performed as well as the
Panasonic 450-C with the Panasonic SE-405.
Kirk Bayne
loudorren
Well-known Member
Hello QQer's,
Cai and Ken, Thanks for the kind words,
kfbkfb,
Kirk,
I spoke to Stephen Traiman after that article was published and set him straight. He never printed an addendum. After the RCA tests that we did to convince them and Warner Bros. about CD-4, everybody knew there was going to be a supply problem of the new compound Q-540 to all of the pressing plants that were going to make CD-4 records. The old vinyl was not soft, however, it was very static prone. The 3 dB carrier reduction could be instantly corrected by cleaning the disk using the QSI cleaner and the cleaning technique I developed. RCA marketing felt that telling the end user that they had to take good care of the CD-4 records and treat them differently than they would a stereo LP would be a negative. They also thought that since production the of Q-540 compound would be ramped up in 6 months, the 110 gram BS story would be a safer marketing bet.
The RCA engineers were on my side in this dispute. We felt that it was time to show record purchasers how to care for their LPs, be they stereo or CD-4 or for that matter 45 RPM singles. Unfortunately, Marketing always overrides engineering when it comes to consumer interface. So for the first year or so, CD-4 records were pressed on conventional vinyl. These are still perfectly viable CD-4 records. They must be cleaned after each 30 to 50 plays and you will find that the carrier level will remain without loss. RCA APD1-0001 production runs 1 through 8 were on conventional vinyl. Runs 9 on were all on Q-540.
As far as the Stereo Review article, their subjective tests, although quite encouraging did not agree with our lab tests in which the order of performance was: EPC451C, EPC450C, Empire 1000E/X, ADC XLM, Shure V15 Type II. There were 28 more cartridges tested. The ones they listed were in the top 15 in our lab tests.
The reason why the semiconductor strain gage cartridges had the best performance was because no RIAA preamplifier EQ curve is required.
Lou Dorren
Cai and Ken, Thanks for the kind words,
kfbkfb,
Kirk,
I spoke to Stephen Traiman after that article was published and set him straight. He never printed an addendum. After the RCA tests that we did to convince them and Warner Bros. about CD-4, everybody knew there was going to be a supply problem of the new compound Q-540 to all of the pressing plants that were going to make CD-4 records. The old vinyl was not soft, however, it was very static prone. The 3 dB carrier reduction could be instantly corrected by cleaning the disk using the QSI cleaner and the cleaning technique I developed. RCA marketing felt that telling the end user that they had to take good care of the CD-4 records and treat them differently than they would a stereo LP would be a negative. They also thought that since production the of Q-540 compound would be ramped up in 6 months, the 110 gram BS story would be a safer marketing bet.
The RCA engineers were on my side in this dispute. We felt that it was time to show record purchasers how to care for their LPs, be they stereo or CD-4 or for that matter 45 RPM singles. Unfortunately, Marketing always overrides engineering when it comes to consumer interface. So for the first year or so, CD-4 records were pressed on conventional vinyl. These are still perfectly viable CD-4 records. They must be cleaned after each 30 to 50 plays and you will find that the carrier level will remain without loss. RCA APD1-0001 production runs 1 through 8 were on conventional vinyl. Runs 9 on were all on Q-540.
As far as the Stereo Review article, their subjective tests, although quite encouraging did not agree with our lab tests in which the order of performance was: EPC451C, EPC450C, Empire 1000E/X, ADC XLM, Shure V15 Type II. There were 28 more cartridges tested. The ones they listed were in the top 15 in our lab tests.
The reason why the semiconductor strain gage cartridges had the best performance was because no RIAA preamplifier EQ curve is required.
Lou Dorren
Last edited:
Justforthesoundofit
Member
- Joined
- Jul 10, 2007
- Messages
- 16
Lou,
In reading you responses to what sometimes is the same question asked again, you must be a very patient person. Thank you for that!
Rick
In reading you responses to what sometimes is the same question asked again, you must be a very patient person. Thank you for that!
Rick
loudorren
Well-known Member
Hello CD-4ers,
For all who are waiting for the QSI record cleaning kits, here is an update. The kits are waiting for the stylus cleaning brush to arrive and then they will ship. Vendor has shipped but I have not received yet. I will post when they get here.
Lou Dorren
For all who are waiting for the QSI record cleaning kits, here is an update. The kits are waiting for the stylus cleaning brush to arrive and then they will ship. Vendor has shipped but I have not received yet. I will post when they get here.
Lou Dorren
roundhousequad
400 Club - QQ All-Star
Hello Lou
can we mod or make this unit cut CD-4 records
*bay number 230256388248
just am idea
thank you
can we mod or make this unit cut CD-4 records
*bay number 230256388248
just am idea
thank you
The Quadfather
1K Club - QQ Shooting Star
Interesting. But I believe this is nothing more than a linear tracking turntable. It is not a cutting lathe. Such a turntable would have been used in a radio station. Industrial grade.
The Quadfather
PS, Look for a Neuman Lathe.
The Quadfather
PS, Look for a Neuman Lathe.
vinylguy4
701 Club - QQ All-Star
Getting a bit off subject, but if you want to cut a CD-4 record, this is probably the best place to go. SR/2 is still cutting records. Check your records for SR/2 in the runout area.
http://www.stanrickermastering.com/
vinylguy4
http://www.stanrickermastering.com/
vinylguy4
Regarding making a CD-4 test disc
(using a 1/2 speed record cutting system):
Prepare a single channel of pseudo-music
(noise that has a frequency spectrum similar
to most music) plus noise with a frequency
spectrum just like the FM based difference
signal carriers.
The pseudo-music would have a bandwidth of
15kHz and the other noise would be band limited
to 20kHz to 45kHz.
The relative levels of the 2 noise signals would
be set to CD-4 standards.
The single channel signal would be put on the
Left channel and then the Right channel of the
2 channel master.
Cutting this 2 channel master recording on a
1/2 speed record cutting system would test
(bandwidth and separation up to 45kHz) the
ability of the cutting system and the record
pressing process to handle CD-4.
(I don't know how much making such a test
master recording, cutting the master disc
and pressing test records would cost)
Kirk Bayne
(using a 1/2 speed record cutting system):
Prepare a single channel of pseudo-music
(noise that has a frequency spectrum similar
to most music) plus noise with a frequency
spectrum just like the FM based difference
signal carriers.
The pseudo-music would have a bandwidth of
15kHz and the other noise would be band limited
to 20kHz to 45kHz.
The relative levels of the 2 noise signals would
be set to CD-4 standards.
The single channel signal would be put on the
Left channel and then the Right channel of the
2 channel master.
Cutting this 2 channel master recording on a
1/2 speed record cutting system would test
(bandwidth and separation up to 45kHz) the
ability of the cutting system and the record
pressing process to handle CD-4.
(I don't know how much making such a test
master recording, cutting the master disc
and pressing test records would cost)
Kirk Bayne
Did lots of Brads work at MF.
loudorren
Well-known Member
WOW!!! Now THAT is sweeeeet! Can't wait for the real thing. Thanks Lou.
Wow. These are going to be in high demand - - - - at least around here!
Very cool! An instant collectable.
