Wanna buy a Marantz CD-400B CD-4 disk demodulator ? Cosmetically fair, and I checked that is works by injecting a carrier from a generator with a VCG function and modulated it. It was loosely coupled ca pacitively to the input, a wire near the jacks with the cover off. The sign al came out of the outputs. I have a picture of that setup working.
Of course I have no CD-4 records, and no compatible cartridge, but I know i t works.
Or, this.
I actually own one of these, in working condition. Kinda-sorta like cotton candy or foot-long hot dogs - not something one does every day, but nice on occasion.
Peter Wieck Melrose Park, PA
Lenny,
The Sansui surround system was called QS. It wasn't very successful. I noticed a few QS records on EBay including one by a Chicago folk singer Bonnie Koloc on Ovation records. I bought this album in the early 70s and, if you like poppy folk music, it would make an ideal test record to experience QS quad . Chuck
Lenny,
The Sansui surround system was called QS. It wasn't very successful. I noticed a few QS records on EBay including one by a Chicago folk singer Bonnie Koloc on Ovation records. I bought this album in the early 70s and, if you like poppy folk music, it would make an ideal test record to experience the QS quad experience. Chuck
the QS and SQ systems were pretty much the same. they cancelled the L+R out of the rear speakers but usually had a filter to not cancel the bass so yo u get it from all speakers, which were usually matched back them. Some may have suppressed some of the L-R in the front pair for a better sound image.
Still, it was all derived from 2 channels. they just took care to mix it ri ght. not like Beatles - Taxman, CCR - Suzie Q, Swinging Medallion - Double Shot Of My Baby's Love. none of them work well on either system because of the way they're mixed.
They tried to sell this 90 degree phase shift as a buzzword but yes, there was but only at a certain frequency because of the high pass filter applied to the signal used to ull the L+R in the rear.
Most schemes of this type did not completely hull out the L+R in the rear t o maintain some separation between LR and RR. this is where the mixing came in. they had digital delay and some of them, for directionality of the sou rce in the front used that instead of a normal pan pot. This made it appear i the rear, if they chose, at the same level as in the front but with a ce rtain aberration in the frequency response.
Adit was no use having 4 channel discrete unless it was recorded in 4 chann el discrete. I had a 4 channel 8 track and a player and found that a Grand Funk tape had noting but mono in the front and L-R in the rear. I could hav e done that easily. Just a few transistors or maybe OP AMPs. In act I did m ore than that :
And that is with not one active component. Some had elfakeo quad that just lifted the common from the rears, or did it with a resistor, this is just a enhancement of that. And i have done it and it sounds good. Pure 5.1 Dolby surround with no effects does exactly the same thing but hides it in an IC . Dolby does not even deserve to have their name on it. All their modes n s hit, none of which I or any audiophile can stand, are a different story. Di gital delay, that is not high fidelity because it does not put out the same waveforms as put into it. Adding and subtracting components still leaves t he original intact, an effect like delay does not.
What other 4 channels were there ? Dynaquad comes to mind, I don't remember who did that. Marantz had SQ you could add at the bottom of their receiver s, and also varimatrix that gives the user control over just how much L+R i s removed from the rear channels. But no high pass. what I did was to just use it, remove not quite all of the L+R which was at about the 2:00 positio n on the control, and then boost the living shit out of the bass in the Rea r. Any and all bass that was out of phase was highly boosted and it produce d a quite pleasing effect. You should have heard Days Of Thunder on it. And all scifi with space ships, they went over your head on the screen that is where the sound went. And Days Of Thunder, when they went around the track , that is how the sound reproduced it.
Anyway, I prefer these old schemes to the ew ones. I don't like the one woo fer idea, people say bass is non-directional but I CAN PROVE OTHERWISE, and those stupid balsa wood speakers, they sound like shit. The only little sp eakers in a subsat system i ever liked the sound of were Bose Acoustimass e arly system. Even they lacked a bit in the crossover point. Keep the speake r systems together. A subwoofer only augments, not supplies all the bass. J ust that bottom octave. Now THAT is nearly non-directional.
Needless to say I will not be buying any of this new shit. If I have no cho ice, I will have no stereo. The last time that happened was when I was home less, and that was over 4 decades ago. I do not want this new shit.
On Friday, June 22, 2018 at 4:35:46 PMl UTC-4, snipped-for-privacy@gmail.com wrote :
r the protection relay to activate and turn on the speakers I finally took it out of service. I recall that it had no other problems that were eviden t. I had posted this problem at that time and I think that it was Chuck up in Canada who nailed it immediately. He recommended changing C6 on the prot ection board and .that resolved the protect relay problem. Now however ther e is another problem that I never had before. Most of the dial lights incl uding the signal meter light are out and that meter also seems to be inoper ative as well. I never had any trouble with any lighting or the signal mete r on this receiver. This is a big quadrophonic receiver. The switching is d one through the main selector switch and it's a nightmare to get to. A real rats nest. Does anyone who has worked on these recall any common problems with lighting on one of these? I suspect a ground problem because so many of these lamps are in parallel but it's so crowded in that area you can't s ee anything. I Really appreciate any help. Lenny
Thanks for the interesting write up on 4 channel Jurb. It seems like my rec eiver, being built around 1974 was at the pinnacle of the 4 channel craze. I never really got involved in 4 channel at the time but it's nice to know that I now have a working remnant of that era. And it really sounds good to o. And my profound thanks to Chuck, who as a former Sansui technician reall y offered some good tips along the way. I couldn't have done this without a ll your help. Lenny
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