2. Half-speed cutting was already perfected by the Decca/Telefunken team in 1958. That's what they used to master the Decca FFRR records.
Let me say it again. Half speed cutting problems were already solved.
With a prehistoric Neumann cutting head.
Which was so old it wasn't even branded "Neumann" but "Telefunken-Decca"
Which was so old its armature wasn't even 45-45 degrees but horizontal-vertical.
Go listen to those Decca/London FFRR records. They sound beautiful. They do have enough bass.
You just posted that for capturing the 50KHz bandwidth of CD4 you need 90000KHz of sampling frequency. This isn't true. Thus, i insist you should check out the Nyquist sampling theorem. Science, it works.
I hate to say it...
There is no rhyme or reason to an Analogue CD4 medium today.
Producing new multitrack recordings - you might as well use the DVDA format... or any of the current PC audio multitrack container formats.
Any CD4 on vinyl will struggle with all the compromises involved, and will be compromised by it in the end.
Which is not to say we should not have CD4 rigs - the vintage material is there and should be enjoyed!
If someone is already making a multi-track recording and wants to issue it in CD4 for those who prefer the rituals of analogue to those of digital - cool!
But it is just a fun thing to have and not an attempt to produce something superior.
Standard stereo LP's can sound superb, and do so to a substantial degree because of the efforts that went into making CD4 work - they led to a quantum jump in record technology/capabilities throughout the chain.
Let's face it - Digital is superior in 99.9% of cases and almost all top end recordings today are done digitally...
Producing CD4 recordings today is like producing Pianola rolls.... nothing wrong with it and good fun. But lets not stress about it!
bye for now
Hi David, i understand your point. But for example we can say "what is the point on releasing LPs from a digital master today?" Yes, there is a point, as i've said before: First, the LP is a good enough medium to transport such audio with no subjective loss of quality. Second, people who have a high-end turntable system not necesarily have a high-end D/A converter. Third, the LP medium is aesthetically more pleasant.
So that above applies to stereo records, and i'd venture to say it can also apply to CD4 records. It looks as a complex system, David, but isn't THAT complex. In any case, yes, let's do it for fun.
Greetings! Nice to see you in this forum too!
Pablo Roufogalis L.
(The Ambiance Pariah)
Looking for aural bliss in CD-4 reproduction may not be a good bet.
Hopefully, we will soon see if Lou's demodulator brings us a step closer.
Given the advances in digital recordings and players, maybe the optimum path is to process existing mixes and play back via DVD-A/SACD media. Or digital files. Just as the generous converters already do now.
Anally, I'd love to have digital recordings done from two-channel, but I'm sure using a four-channel recording from a good demod would be virtually the same or better, as a starting point. What would be needed is to assess the compromises made for CD-4 cutting and compensate for them as possible, all in the digital domain.
Pablo Roufogalis L.
(The Ambiance Pariah)
hmm and no need to waste too much space - CD4 is 15k bandwidth limited - so digital version would be either 1x24/96 (to 48kHz) or 2x24/32 (to16kHz)
2 x 24/32 will take less space and be easier to play back (no decoding) - but harder to create (has to be decoded into the file packages)
Remember, at 96K there's only two samples per cycle of the highest frequency, which would indeed be 48K. The CENTER FREQUENCY of CD-4 is 30K, then it modulates down to 20K and up to 45K. So it depends on how good of a resolution you want for the top end of the albeit-limited program bandwidth, but also how good of a resolution you want for the top end of your demodulation frequency. See below under ``resolution''.
The only thing you can capture perfectly in digital with two samples/cycle is a pure sine, square, saw, etc wave.
It's the same as in film or TV. If all you needed was the minimum, why have they developed 1080p and why are they developing in Japan 16K ganging together multiple 4K or 8K scanners and now the newest ones 24K scanning when supposedly 2K scanning is already smaller than the film grain resolution it's trying to capture?Originally Posted by diamoneOriginally Posted by diamone
Go over on the Lathe Troll Forums http://lathetrolls.phpbbweb.com/lathetrolls.html and make that same statement and see how fast you get ROUNDLY trounced.
http://www.diyaudio.com/forums/analo...ml#post2585729. I suggest you go check out the
Lathe Trollers or any of the other ``prehistoric'' cutting forums populated by ``prehistoric'' engineers that have been in this field since before you were born and see the responses you get.
Or, better yet, go call up Steve Marcussen or Doug Sax or Bernie Grundman or anybody like that and see what kind of response you get from them .Originally Posted by diamone
Just turn the page when you hear the :raspberry:.
The rest of you guys, if you want to laugh, go slide down to some of his other posts in the DIY and other related forums he belongs to and see how He Can't Handle the Truth.
http://www.diyaudio.com/forums/analo...ml#post2585794 :LOL: Like we live to prove a kid wrong. Please.
Gearslutz. :LOL: :raspberry:.That's like saying you get all your World News from the National Enquirer.
And, you'll notice in Jamie's response that conventional electronics you espouse so fondly are a hit-and-miss affair AT BEST nevermind anything anybody would actually advise using.
Pick a side, kid and stick with it. You can't play both sides on the middle.
Kids and their book-learning. . Kayyyyyyyy....next topic!
I know what the mastering engineers are saying, that it's only when you try to overdrive an amp that you can tell between the solid state/digital technology that amplifies the ODD harmonics, giving the music an edgy feel vs. that of the tube amp which amplifies the EVEN overtones giving the music a warmer feel, but how many engineers even in those days liked to stay within parameters?
I put it up and play it for company just to trip people out next to my Madonna Blue Amberol cylinder re-creation of her singing Crazy for You from Vision Quest on a restored 1925 player.
Claghorn here Senator Claghorn that is. I'm from the South. I'll never go to the Yankee Stadium `less `en it's a Southpaw pitchin. That's a joke, son. Get to laughin'. Don't all you kids be a-pooh-pooh-in' people's efforts so fast to be bringin' back and improvin' vintage technologies. Set-a-spell and ya might ah-say ya might learn somethin' boy.
Last edited by ndiamone; 06-16-2011 at 07:16 PM.
"The ANRS has a variation on the basic compander. It divides the companding scheme into two frequency
bands. This technique is similar to Dolby C noise reduction with the exception that the frequency bands
for CD-4 ANRS are different than Dolby C. The CD-4 has a low mid compressor that has a mid bandpeak at 630 Hz and a high band compressor with a peak at 15KHz."
So correcting what i said before: Seems that what you do is you filter the input applying two different EQ curves (the one with the peak at 630Hz and the other with the peak at 15KHz) and the amplitude obtained after passing the input through the combination of said curves is the amplitude to feed the compressor with. In other words, the control signal for the compressor.
The idea is to achieve more noise reduction at one band vs the other.
This is a forum for technical discussion, not for flame wars or lengthy self-aggrandizing autobiographical ramblings. It is not a blog but a forum. And we're discussing CD4 demodulation. You should at very least stay on topic.
I'll leave the rest of the participants in this forum -who ARE staying on topic and contributing valuable thoughts- to decide who is participating here because of a genuine interest in CD4 audio, and who is not.
Please treat each other with respect or I'm going to nuke any post that is not related to the new Lou Dorren CD-4 demodulator. You are free to start your own thread on your own philosophies.
Sorry for not reading this post of yours. On VE i've uploaded a review of the EPC-450C-II, you can see that the frequency response published there has what it looks like a shelf-filter 5.5dB rise from 15KHz. Then it stays healthily up at that level. I bet this was intentional to help with carrier recovery. I can read your mind and i bet you are currently thinking on what is the resonance freq of that cart ... Your guess is as good as mine, but if i was the cartridge designer i'd choose 38KHz as the res freq, since that's the center of the carrier freq.
On your SE-405 you have a rather sharp filter after 15KHz, so the combined freq response of your EPC451C with the SE-405 will have a "bell" at about 15KHz. Not nice... That's why you should better try Lou's preamp or my cheap and dirty preamp schematic. In any case, i'm 100% sure your channel imbalance problem is on the preamp, not on the cartridge, so Lou's demodulator/preamp should not show that problem.
PS: Maybe you would like to read US patent #3975025, it is the patent for that cartridge
Let's discuss this on VE, since we're going off topic. Greetings!!
the SE405 suddenly lost a channel so I pulled them out and decided to wait for LouD's decoder.... alternative being to use your circuit diagram.... but I am hesitant to get into soldering/making electronics....
So for now the EPC451C is lying idle..... waiting....
CD-4 is a quality medium, not like old grammophone records. It was invented at the pinnacle of the analog phonograph recording technology. And it improved on it. When it is set up right, it can sound just as warm as a stereo LP, only in quad. And I think that it can be improved. That is why it should be attempted by anyone who cares enough to do so. But it would be a labour of love. Just as is Lou's demodulator.
From what i've read today, ANRS (as used on JVC cassette recorders) was directly compatible with Dolby B. It seems that it was JVC's way of incorporate Dolby B without paying royalties... and JVC lost some lawsuits to Dolby Laboratories because of this!!. If this ANRS used on JVC's cassette recorders is exactly the same ANRS that is used in CD-4, then you can use dolby B decoding, which is well documented elsewhere.
BTW they had a "Super ANRS" system which... seems to be Dolby C in disguise. LOL!!