Yes, but the carrier survives, without bypass.
Non-LP sources of CD-4 music
- Thread starter No Quarter
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Excellent explanation of why trying to get CD4 carrier out of an RIAA preamp won’t be successful.
I suppose that It would depend on the design of the actual demodulator.
This diagram from the Panasonic SE-405H manual (the demodulator that jupp369 is working with) illustrates just what he is saying. The RIAA comes first.
This diagram from the Panasonic SE-405H manual (the demodulator that jupp369 is working with) illustrates just what he is saying. The RIAA comes first.
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Here is a JVC diagram that shows the RIAA done as a separate path.
When I did some service work on a Marantz 400-B I was surprised to see the RIAA EQ pre-amp was also done before low/high pass filtering. That really seemed odd to me. But as you have demonstrated it seems to be done both ways depending on the unit.
In the SE-405H scheme "Equalizer" is the RIAA.
The JVC scheme comes after the RIAA and what is signed as "EQ" is an internal pre amp to lift the signal.
(I have 3 amp's from JVC) In 5436 and GX500 the RIAA is on a separate circuit board, In 5446 the RIAA is on the demod board.
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as I said: from win7 on the max input freq is limited to 48kHz (/2). Win XP did it well. So I use a cheap external guitar to USB (Focusrite Scarlett 2i2 3rd Gen = 150$) which goes up to 192/24 and have no more problems with hum.
(From win 7 on there is also a limiter for the audio out. For playback it has to be lifted. Realtek can do, my HP's can not)
The JVC diagram is from their publication "Discrete Four Channel Record System" that describes the operation of CD-4, I haven't investigated their demodulators actual circuitry. RIAA is specified to what, 20 KHz? You would expect it to roll off even more beyond that point but it doesn't have to. Obviously the carrier has to make it through! Seems an odd why to do things though, but no point in second guessing the designers choices!
Thanks Ken that was a very interesting piece of data I haven't seen before.
II am drawn to the paragraph under Recording Process which says:
"Regarding the difference signal, the ranges lower than 80Hz and higher than 6KHz are frequency modulated (FM) and range between 800Hz and 6KHz is phase modulated (PM)."
Firstly I'll say I think there is a typo there as I think it should say the range between 80Hz and 6KHz is PM.
Now this is just plain crazy to me. Very low and quite high frequency's are FM but the mid-range is PM?
I have always read that the carrier signal was simple FM. What would be the benefit to using two different forms of modulation? Or would the demodulator simply see them as both the same?
Maybe I can't see the forest for the trees? I would appreciate someone knowing more than me explain this!
Yes the carrier is actually a combination of FM-PM-FM as to why without further research I can only guess, maybe it is desirable not to vary the carrier frequency too much? FM and PM are related, but why the combination of both?
Perhaps there is an explanation in"Quadraphile", or in the patent document. So sad that Lou Dorran passed on, he could've given us the answer I'm sure!
Perhaps there is an explanation in"Quadraphile", or in the patent document. So sad that Lou Dorran passed on, he could've given us the answer I'm sure!
It was a modulation combination for the lowest distortion possible in CD-4.......document from "A better understanding of CD-4"
The Quadfather
1K Club - QQ Shooting Star
You know, it seems to me it would be much easier to record into the computer a demodulated 4 channel signal. Use a 4 channel input audio card to do it. I have a DTS encoder I can use to burn CD's with DTS signal and I can copy 4 channels that way. That doesn't even require a computer. Just a DTS encoder and an audio CD burner.
The Quadfather
1K Club - QQ Shooting Star
I think that phase modulation is essentially similar to frequency modulation, but it happens within a cycle. FM is much more sweeping and a cycle of audio may sweep several cycles of RF. The PM would handle the treble, and the FM would handle the bass. And with all the frequencies in between, the dividing line between the two would be somewhat blurred. That's why you need only one PLL circuit to decode them both.
Goldwave can digitize an audio input up to six or eight channels (I checked recently, but forgot). It can store as .wav or .flac, along with about ten other file formats and compression schemes. And it’s about $30, with lifetime upgrades. If you’re just ripping, and you have decent CD4 capabilities, it’s one way to go.
Doug G.
2K Club - QQ Super Nova
I'll just keep doing it the old fashioned way.
Doug
Doug
The Quadfather
1K Club - QQ Shooting Star
There was a company that was selling DTS encoders as a way to connect a 5.1 analog output to a Toslink optical input on a modern surround receiver. It also had a RCA digital output. The cool thing was that if you had a hardware CD burner, you could record a CD in DTS and it would play back in surround. I don't recall the make or model, but I did buy one. And I did make a few CD's which I used in my truck system. I could also record off any other part of my home surround setup. The problem was that you really couldn't hear the surround effect very well in a pickup truck, especially with a bunch of tools in the back seat covering the speakers half the time. But it did work quite well. I gave the disks away as samplers to people who might be interested in the quad hobby.
I was using the Minnetonka SurCode CD, DTS encoder software, years ago. They added a new version that did DVD as well. Unfortunately the product is considered obsolete and is no longer available for sale.
You can still download the trial version which is rather useless. I was able to find the crack for the DVD version after much searching. As I recall I could only download and install with the crack on Windows 7. Damn Win 10/11 likes to block everything that Microsoft deems to be questionable!
DVD Audio Extractor also allows conversion to DTS.
I realise that we are getting away off topic but back in the day DTS-CD was "the way" to archive our discrete CD-4 and Q8's. I still have a large collection of DTS CD's with many of my Q8's on them.
You can still download the trial version which is rather useless. I was able to find the crack for the DVD version after much searching. As I recall I could only download and install with the crack on Windows 7. Damn Win 10/11 likes to block everything that Microsoft deems to be questionable!
DVD Audio Extractor also allows conversion to DTS.
I realise that we are getting away off topic but back in the day DTS-CD was "the way" to archive our discrete CD-4 and Q8's. I still have a large collection of DTS CD's with many of my Q8's on them.
Wow, I missed quite a few posts in this thread - there is a lot of great info here! Unfortunately, life got in the way and I never pursued this. I do have a Sound Devices MixPre 6 II (https://www.sounddevices.com/product/mixpre-6-ii/), so it's probably the best and easiest route at my disposal should I ever get off my rear end, hook it up, and just start transferring.
Has anyone managed to needledrop CD4 records, so you can feed the file into a decoder?
I assume if you have a +30kHz capable stylus & cart combo, bypass the RIAA, and record it into a DAW, you could then feed that into a decoder from the digital file?
An option to back up all your CD4 records. Maybe a better software decoder will become available too: all those old electronic devices may not last forever.
I assume if you have a +30kHz capable stylus & cart combo, bypass the RIAA, and record it into a DAW, you could then feed that into a decoder from the digital file?
An option to back up all your CD4 records. Maybe a better software decoder will become available too: all those old electronic devices may not last forever.
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