Lou Dorren: A new CD-4 Demodulator!!! [ARCHIVE]
- Thread starter loudorren
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loudorren
Well-known Member
Hello Quadrapreneurs,
In the research that we did for the QSI record cleaner, one of the concerns were micro cracks in the disk surface. We had some advantages over most with the availability of electron scan microscopy and acetate and lacquer CD-4 disks. A short time later I had some shellac 78s to recover.
One of the characteristics of most liquid record cleaners is the combination of alcohols with other inert liquids. Most common is Ethyl alcohol (ethanol CH3CH2OH) which has two unique properties. First, it is a great solvent and second it mixes completely with water because of mutual solubility regardless of individual liquid proportions. Unfortunately, this kind of record cleaning compound reeks havoc with vinyl, acetate, lacquer, and shellac surfaces. The surface reaction is one of deterioration of the disk compound. This problem exacerbates itself as the cleaner leaches into the micro cracks on the surface. This can result in the complete breakdown of the disk surface.
The QSI record cleaner contains no alcohol. Instead, it is formulated to enhance the disk surface. Besides cleaning the surface by liquefying and suspending the dirt to be scooped out by the playback stylus, It has a unique property for disk restoration for record archiving. When used properly, it fills in the micro cracks in the disk surface providing a hydrodynamic suspension effect. As the stylus plays the groove, this effect significantly reduces the stylus undulation created by the micro crack. I have measured a greater than a 20 dB impulse noise reduction which is a big difference when restoring old disks. The complete "how to" technique is described in the information sheets that come with QSI cleaner.
One last thought about the cleaner. It is absolutely safe for all disk and disc surfaces. It was designed that way.
Lou Dorren
In the research that we did for the QSI record cleaner, one of the concerns were micro cracks in the disk surface. We had some advantages over most with the availability of electron scan microscopy and acetate and lacquer CD-4 disks. A short time later I had some shellac 78s to recover.
One of the characteristics of most liquid record cleaners is the combination of alcohols with other inert liquids. Most common is Ethyl alcohol (ethanol CH3CH2OH) which has two unique properties. First, it is a great solvent and second it mixes completely with water because of mutual solubility regardless of individual liquid proportions. Unfortunately, this kind of record cleaning compound reeks havoc with vinyl, acetate, lacquer, and shellac surfaces. The surface reaction is one of deterioration of the disk compound. This problem exacerbates itself as the cleaner leaches into the micro cracks on the surface. This can result in the complete breakdown of the disk surface.
The QSI record cleaner contains no alcohol. Instead, it is formulated to enhance the disk surface. Besides cleaning the surface by liquefying and suspending the dirt to be scooped out by the playback stylus, It has a unique property for disk restoration for record archiving. When used properly, it fills in the micro cracks in the disk surface providing a hydrodynamic suspension effect. As the stylus plays the groove, this effect significantly reduces the stylus undulation created by the micro crack. I have measured a greater than a 20 dB impulse noise reduction which is a big difference when restoring old disks. The complete "how to" technique is described in the information sheets that come with QSI cleaner.
One last thought about the cleaner. It is absolutely safe for all disk and disc surfaces. It was designed that way.
Lou Dorren
Special! I'm a-waitin' --bd
Regarding CD-4 and Disc Cleaning Systems:
How does the QSI cleaning system compare to
the Discwasher system?
Do products such as Sound Guard and Last
(which leave a coating on the disc) offer any
improvements in CD-4 fidelity and longevity?
Discwasher apparently didn't test CD-4 discs:
http://www.audioasylum.com/audio/vinyl/messages/881.html
Kirk Bayne
How does the QSI cleaning system compare to
the Discwasher system?
Do products such as Sound Guard and Last
(which leave a coating on the disc) offer any
improvements in CD-4 fidelity and longevity?
Discwasher apparently didn't test CD-4 discs:
http://www.audioasylum.com/audio/vinyl/messages/881.html
Kirk Bayne
loudorren
Well-known Member
Hello Quadriacts,
kfbkfb,
Kirk, I read the link you sighted and with all respect to him, Jon Risch must be having a dream. The absolute best no signal noise floor is obtained on the first play of a master lacquer. That is in the range of -65 to -68 dBm. The best pressing no signal noise floor at the first play is between -55 to -62 dBm. The electroplating processes that are used to make mothers and stamplers degrade the signal to noise floor about 3 dB per step. The grain of the record compound can degrade the noise floor as much as an additional 5dB. The Q540 compound which was the one developed for CD-4, turned out to have the finest grain and an average noise floor deterioration 2 to 3 dB.
Most of the non alcohol record cleaner liquids use a base loaded detergent for cleaning. These are OK as long as the record is thoroughly rinsed with distilled water and then air dried in a dust free environment.
Commercial: QSI record cleaner works differently by emulsifying dirt on the record surface and using the playback stylus as a scoop to actually remove the dirt.
Risch's writings about square wave harmonic deterioration is at best fallacious. CD-4 records have much higher frequencies than anything that he "tested". The kind of deterioration he sighted would require tracking pressures greater than 5 grams creating a groove gouger not a playback stylus.
Lou Dorren
kfbkfb,
Kirk, I read the link you sighted and with all respect to him, Jon Risch must be having a dream. The absolute best no signal noise floor is obtained on the first play of a master lacquer. That is in the range of -65 to -68 dBm. The best pressing no signal noise floor at the first play is between -55 to -62 dBm. The electroplating processes that are used to make mothers and stamplers degrade the signal to noise floor about 3 dB per step. The grain of the record compound can degrade the noise floor as much as an additional 5dB. The Q540 compound which was the one developed for CD-4, turned out to have the finest grain and an average noise floor deterioration 2 to 3 dB.
Most of the non alcohol record cleaner liquids use a base loaded detergent for cleaning. These are OK as long as the record is thoroughly rinsed with distilled water and then air dried in a dust free environment.
Commercial: QSI record cleaner works differently by emulsifying dirt on the record surface and using the playback stylus as a scoop to actually remove the dirt.
Risch's writings about square wave harmonic deterioration is at best fallacious. CD-4 records have much higher frequencies than anything that he "tested". The kind of deterioration he sighted would require tracking pressures greater than 5 grams creating a groove gouger not a playback stylus.
Lou Dorren
Bonzodog
300 Club - QQ All-Star
- Joined
- Jul 12, 2007
- Messages
- 387
ingresman
300 Club - QQ All-Star
Hi Lou,
You mentioned in one of your posts that the tate is not a clever as generally thought. What are your thoughts around this?, would it be possible to implement one in software possiblty using something like Adobe Audition.
also there has been debate on this site about doing CD-4 in software , do you have any thoughts around this as well?
also much support for doing this job !
Regards
You mentioned in one of your posts that the tate is not a clever as generally thought. What are your thoughts around this?, would it be possible to implement one in software possiblty using something like Adobe Audition.
also there has been debate on this site about doing CD-4 in software , do you have any thoughts around this as well?
also much support for doing this job !
Regards
loudorren
Well-known Member
Hello CD-4 Fans,
ingresman, Tate is simply a audio signal level and phase steering system. It is based on level and phase comparators that control VCAs (Voltage Control Attenuator) to control the output volume of the 4 channels. As I wrote in another post, if only one signal at a time is sent, it is possible with Tate to make that signal go around the room. It is also possible to display 2 channels, but any more than two channels (3 or 4) and the information theorem has been exceeded and all bets are off.
With CD-4 in software, the deal is speed. There is enough system speed to be able to Quantize the left and right CD-4 composite signals and record them digitally. You would need a sample rate of at least 96kHz (192kHz would be better). 16 bit quantization is more than enough (stereo LPs and CD-4 LPs have a dynamic range of approximately 12 bits)to do the job. These parameters are well within today's technology. Processing in software is quite another story. It would require a super computer to do it on one platform and even that might be pushing the envelop. Algorithmically, you are looking a 9 simultaneous Fast Fourier Processes and 12 algebraic ones plus all the synchronization code to tie the whole thing together. I calculate that you would need a PC running at 30 GHz to do it. You might be able to accomplish the CD-4 task by using 10 to 12 3.5 GHz PCs and distributing the CD-4 job among them.
Lou Dorren
ingresman, Tate is simply a audio signal level and phase steering system. It is based on level and phase comparators that control VCAs (Voltage Control Attenuator) to control the output volume of the 4 channels. As I wrote in another post, if only one signal at a time is sent, it is possible with Tate to make that signal go around the room. It is also possible to display 2 channels, but any more than two channels (3 or 4) and the information theorem has been exceeded and all bets are off.
With CD-4 in software, the deal is speed. There is enough system speed to be able to Quantize the left and right CD-4 composite signals and record them digitally. You would need a sample rate of at least 96kHz (192kHz would be better). 16 bit quantization is more than enough (stereo LPs and CD-4 LPs have a dynamic range of approximately 12 bits)to do the job. These parameters are well within today's technology. Processing in software is quite another story. It would require a super computer to do it on one platform and even that might be pushing the envelop. Algorithmically, you are looking a 9 simultaneous Fast Fourier Processes and 12 algebraic ones plus all the synchronization code to tie the whole thing together. I calculate that you would need a PC running at 30 GHz to do it. You might be able to accomplish the CD-4 task by using 10 to 12 3.5 GHz PCs and distributing the CD-4 job among them.
Lou Dorren
S
sq10
Guest
OK, kids,
After months of being a QQ member and wondering "what the hell is that Lou Dorren thread?", I have read thru most of it.
I'm not as big of a tech head as a lot of you and sometimes there's a "WHOOOSH" above my head but what I wanna say is ..
"COUNT ME IN FOR ONE OF LOU'S CD-4 DEMODULATORS"
That way I can listen to the ONLY CD-4 LP I have....
Cheers...
BTW , I also put in my order for the cleaning set...but I live in Spain, I guess I'll have to pay extra for the S&H, lemmeknow....
After months of being a QQ member and wondering "what the hell is that Lou Dorren thread?", I have read thru most of it.
I'm not as big of a tech head as a lot of you and sometimes there's a "WHOOOSH" above my head but what I wanna say is ..
"COUNT ME IN FOR ONE OF LOU'S CD-4 DEMODULATORS"
That way I can listen to the ONLY CD-4 LP I have....
Cheers...
BTW , I also put in my order for the cleaning set...but I live in Spain, I guess I'll have to pay extra for the S&H, lemmeknow....
S
sq10
Guest
Curiosamente, I was given Jefferson's Starship's "Red Octopus" by my brother Pepe, he goes to the Salvation Army in Old San Juan to get all kinds of used Lps for $1....
But, since so far I've been collecting (please be forgiving,
) only SQ LPs , I REALLY don't wanna find out how much dough I'm agonna shell out for a lot of CD-4s I'm looking forward to ...
Regarding long term availability of the
QSI cleaning system:
Perhaps the formula could be licensed to a web based
business such as http://www.needledoctor.com or
another similar business.
Kirk Bayne
QSI cleaning system:
Perhaps the formula could be licensed to a web based
business such as http://www.needledoctor.com or
another similar business.
Kirk Bayne
Hey Y'all:
I have been testing an old AT14S for which I was able to get a new (old stock) stylus. As a comparison to my other cart, the AT440MLa. I have played the AT14S through what I believe is a sufficient breakin period, and have concluded that although it's rival, the AT440MLa suffers from excess sibilance, it is the superior cart. I believe it is due to the fact that it has a microline stylus. All else considered, the AT14S should have out performed the AT440MLa, for it has a much wider bandwith according to published specs. Sorry, Mr Shibata, Hats off to you, you are a quad pioneer, but I believe you have been out done. I will probably continue to test the AT14S or just use it on less challenging material, because I have close to a hundred bucks invested in it, but when it's worn out I will retire it permanently. Mr Dorren, I would like to hear your perspective on this, including any mistakes I might have made in my judgement. I tried different trancking pressures, including 1.5 grams, 2 grams and finally, 1.75 grams, which is where I run my AT440MLa with good success. I also tried to bring it in by readjusting the carrier level, but to no avail. I couldn't get it to track as well as the 440MLa. One other difference is that I have the 440MLa in the original Marantz shell, which is heavier than the other shell, but both were zero balanced before adjusting the weighting. I could try weighting the other shell to match the Marantz shell. The theory being that it would keep the cart from reacting to the stylus movement due to higher mass. Both carts were aligned using an alignment protractor. So Whadda ya think?
The Quadfather
I have been testing an old AT14S for which I was able to get a new (old stock) stylus. As a comparison to my other cart, the AT440MLa. I have played the AT14S through what I believe is a sufficient breakin period, and have concluded that although it's rival, the AT440MLa suffers from excess sibilance, it is the superior cart. I believe it is due to the fact that it has a microline stylus. All else considered, the AT14S should have out performed the AT440MLa, for it has a much wider bandwith according to published specs. Sorry, Mr Shibata, Hats off to you, you are a quad pioneer, but I believe you have been out done. I will probably continue to test the AT14S or just use it on less challenging material, because I have close to a hundred bucks invested in it, but when it's worn out I will retire it permanently. Mr Dorren, I would like to hear your perspective on this, including any mistakes I might have made in my judgement. I tried different trancking pressures, including 1.5 grams, 2 grams and finally, 1.75 grams, which is where I run my AT440MLa with good success. I also tried to bring it in by readjusting the carrier level, but to no avail. I couldn't get it to track as well as the 440MLa. One other difference is that I have the 440MLa in the original Marantz shell, which is heavier than the other shell, but both were zero balanced before adjusting the weighting. I could try weighting the other shell to match the Marantz shell. The theory being that it would keep the cart from reacting to the stylus movement due to higher mass. Both carts were aligned using an alignment protractor. So Whadda ya think?
The Quadfather
Hi Quadfather,
your tests are exciting to me since I own the "old" AT440ML (no "a")
They seems to differ in performance (at least in the specs) but I don't know if they really sound different. Any thoughts?
your tests are exciting to me since I own the "old" AT440ML (no "a")
They seems to differ in performance (at least in the specs) but I don't know if they really sound different. Any thoughts?
I don't have a AT440ML with which to compare it. I do understand that the 440ML was rated with a higher bandwidth. The story I heard was that they are essentially the same cart, but the manufacturing technique is different. However, I cannot vouch safe the veracity of that statement. Anyway, as the story goes, AT couldn't get a consistant high end with this technique, so they just rated the cart to be 20 HZ to 20KHZ. I believe the 440ML was rated at about 35KHZ, about the same as the AT14S, and the Trackmaster 8 I used to use. Apparently the 440MLa is better than quoted specs, or it wouldn't work so well with CD-4. And it does work better than anything I've tried so far. Those include:
at14s
Stanton (horrible)
Walco (Horrible)
AT Trackmaster 8 (good)
The Ed Saunders cart (poor)
AT331LC (good)
And finally the AT440MLa which I am continuing to use. (best of all)
Anyway, That's it.
The Quadfather
at14s
Stanton (horrible)
Walco (Horrible)
AT Trackmaster 8 (good)
The Ed Saunders cart (poor)
AT331LC (good)
And finally the AT440MLa which I am continuing to use. (best of all)
Anyway, That's it.
The Quadfather
ingresman
300 Club - QQ All-Star
Lou,
thanks for taking the time to reply to my CD-4 in software question. Is the method you describe for real-time demodulation ?, I would expect any software demod to be along the same lines as the SQ and QS scripts which would just churn away for hours until done.
thanks for taking the time to reply to my CD-4 in software question. Is the method you describe for real-time demodulation ?, I would expect any software demod to be along the same lines as the SQ and QS scripts which would just churn away for hours until done.
jefe1
2K Club - QQ Super Nova
Hi Lou,
I paypaled for the QSI cleaner a while back, so hope I got in the group of 50. When are the kits being shipped?
Thanks
Jeff
I paypaled for the QSI cleaner a while back, so hope I got in the group of 50. When are the kits being shipped?
Thanks
Jeff
loudorren
Well-known Member
hello QQs,
This is just a quick one. I will answer other questions in next post plus a test bench new demodulator update.
Jefe1, Your in, First record cleaning kits ship in 2 weeks.
Lou Dorren
This is just a quick one. I will answer other questions in next post plus a test bench new demodulator update.
Jefe1, Your in, First record cleaning kits ship in 2 weeks.
Lou Dorren
loudorren
Well-known Member
Hello CD-4 crowd,
Quadfather, The AT14S is a CD-4 cartridge with a frequency response to 48 KHz (measured) and separation of 12 dB at 45KHz. The AT440MLA is a stereo cartridge with a manufacturers frequency spec of 20 KHz (measured 33KHz with a separation at 30KHz of 8 dB). I do not recomend the AT440MLA for CD-4 use. The Microline stylus is the same as a Shibata stylus in shape and contact area. If the sibilance you note occurs with CD-4, it is because you are not getting the upper sideband of the sub carrier which is quite critical. If it is happening on stereo LP's and the cartridge mount is correct I would have to believe that you have a damaged cantilever. 2 Grams is the right tracking force for the AT14S. The following is my opinion. The AT14S is an OK cartridge, but far from the best. The AT14SA was much better and the ATP-VM35F was the hot prop.
Ingressman, They churn for hours because they are trying to calculate 4 unknowns with only 2 simultaneous linear equations.
New CD-4 Demodulator update:
The preamp circuit is fantastic and far exceeds the QSI5022. The limiter and RSSI systems as well as the Phase Lock Loop perform well beyond my expectations under FM, PM, and SSBFM modulations. Filter work is almost finished and should be ready by the time the rest of the system is complete.
Lou Dorren
Quadfather, The AT14S is a CD-4 cartridge with a frequency response to 48 KHz (measured) and separation of 12 dB at 45KHz. The AT440MLA is a stereo cartridge with a manufacturers frequency spec of 20 KHz (measured 33KHz with a separation at 30KHz of 8 dB). I do not recomend the AT440MLA for CD-4 use. The Microline stylus is the same as a Shibata stylus in shape and contact area. If the sibilance you note occurs with CD-4, it is because you are not getting the upper sideband of the sub carrier which is quite critical. If it is happening on stereo LP's and the cartridge mount is correct I would have to believe that you have a damaged cantilever. 2 Grams is the right tracking force for the AT14S. The following is my opinion. The AT14S is an OK cartridge, but far from the best. The AT14SA was much better and the ATP-VM35F was the hot prop.
Ingressman, They churn for hours because they are trying to calculate 4 unknowns with only 2 simultaneous linear equations.
New CD-4 Demodulator update:
The preamp circuit is fantastic and far exceeds the QSI5022. The limiter and RSSI systems as well as the Phase Lock Loop perform well beyond my expectations under FM, PM, and SSBFM modulations. Filter work is almost finished and should be ready by the time the rest of the system is complete.
Lou Dorren
Glad to hear that it's coming together nicely, Lou. Anxiously awaiting more updates from the test bench!!
Mark Z
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