Discrete phaser + IC logic

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Has anyone ever tried to build a discrete phaser and apply the 4 outputs to a MC1314 and MC1315 IC's? Or know a commecrial decoder that does it? I just built a discrete circuitry based on transistors, still on breadboard, and now I want to use the MC1314 and MC1315 for logically enhance the separation. I have bought both IC's from ebay, they haven't arrived yet, and I'm thinking of apply the 4 outputs, without the 10/40 blend resistors, to the bases of Q1, Q2, Q3 and Q4 from the Motorola schematic. Will it work? https://www.sm5cbw.se/audio/quad/MC1312-10.gif http://art-and-technology.blogspot.com/2015/12/sq-quadraphonic-dead-surround-audio.html
 

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Sonik Wiz

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Has anyone ever tried to build a discrete phaser and apply the 4 outputs to a MC1314 and MC1315 IC's? Or know a commecrial decoder that does it? I just built a discrete circuitry based on transistors, still on breadboard, and now I want to use the MC1314 and MC1315 for logically enhance the separation. I have bought both IC from ebay, they haven't arrived yet, and I'm thinking of apply the 4 outputs, without the 10/40 blend resistors, to the bases of Q1, Q2, Q3 and Q4 from the Motorola schematic. Will it work? https://www.sm5cbw.se/audio/quad/MC1312-10.gif http://art-and-technology.blogspot.com/2015/12/sq-quadraphonic-dead-surround-audio.html
What?
Ancient technology . Kirk, Spock, et al, used the discrete phaser quite some time ago.
I am stunned.

lo siento.
 
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par4ken

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Years ago I did the same thing with my Audionics 106A decoder board mated to a full logic decoder using the Motorola Chips. The Audionics board boasted six pole phase shift circuits. CBS shows a diagram using discrete components and an eight pole filter, mated to the Motorola chips with vari-blend using a FET.
 

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Sonik Wiz

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Years ago I did the same thing with my Audionics 106A decoder board mated to a full logic decoder using the Motorola Chips. The Audionics board boasted six pole phase shift circuits. CBS shows a diagram using discrete components and an eight pole filter, mated to the Motorola chips with vari-blend using a FET.
Disclord gave me that CBS tech paper ages ago but who knows where it is? So it was fun to reread that piece of history again.

One of the more interesting aspects of the info is the vari-blend. It seems it's not that variable being basically on or off. Since there is frequently a center front vocalist it would be essentially on most of the time. Because of both series & shunt resistance around the blending FET it varied from 20% off to 70% full blend. Comparing L1 (logic no vari-blend ) to L2 with vari-blend it increases front to back seperation by 3dB (15dB > 18dB) & rear L/R separation by 3 dB (12dB > 15 dB). Seems like a lot of effort to squeeze out that little bit.

I really like the idea of taking the Audionics basic decoding & feeeding to the logic chips. Clever. How did that work out & sound in operation?
 

Soundfield

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Disclord gave me that CBS tech paper ages ago but who knows where it is? So it was fun to reread that piece of history again.
Yes, it seems to re-surface every so often, but each time it seems to have been through another generation of copying - at this rate it will soon be illegible! Mind you, I don't think it ever gave the impression of being a particularly professional document. Those hand drawn circuit diagrams always hinted at the whole thing being rushed out in a desperate hurry. I don't think it can have inspired confidence - did anyone ever make the L3 circuit I wonder? I always found it amusing that there was an implicit admission by CBS that the basic Motorola chip set with the cheap phase shifters that most SQ manufactures were using was pretty C%4P!
 

par4ken

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Yes I used my Audionics decoder from about 1972 to 1979 0r 1980 when I got my S&IC. Along the way I purchased a Heathkit (full logic) SQ decoder board, first tried it out stock (and wasn't satisfied) then added the Audionics front end. Worked quite well and the vari-blend does make a significant difference. I recall cranking the amplifiers balance toward the rear when enhancing stereo, not the best way to do it but to me it sure blew away regular stereo.
 
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Years ago I did the same thing with my Audionics 106A decoder board mated to a full logic decoder using the Motorola Chips.
Audionics 106A with a 6-pole phaser, sounds interesting, do you happen to have the schematics or a service manual?
 
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Yes, it seems to re-surface every so often, but each time it seems to have been through another generation of copying - at this rate it will soon be illegible!
The L3 circuit is already illegible. there are reprints of the L1 and L2 with pretty much readible information as you can see on the file above. Not a good idea to call Motorola and ask for a legible print of such datasheet, right? I'm guessing they'll be like either buy a new Moto Z phone or hang up!
 

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Years ago I did the same thing with my Audionics 106A decoder board mated to a full logic decoder using the Motorola Chips. The Audionics board boasted six pole phase shift circuits. CBS shows a diagram using discrete components and an eight pole filter, mated to the Motorola chips with vari-blend using a FET.
So, your guess is that it'll work? Have you added any impedance matching circuit in between this Audionics board and the Motorola chips? Or you just fed the 4 transistors, Q1, Q2, Q3 and Q4, from the schematic above, with the 4 channels of you Audionics decoder?
1574313362899.png
 

par4ken

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As I recall I didn't use the buffer transistors, I just removed them from the board and fed the sinal to the emitter side of the buffer transistor and removed the emitter resistors as well. If you leave the transistors in you would need to bias them with a couple of resistors. I don't have a schematic of the 106A, it was an all discrete transistor design with a lot of electrolytic coupling capacitors, it would be a nightmare to breadboard I'm sure. You would be better off trying to copy the S&IC's headend, it's 8-pole using TL074 op-amps. The only problem with that idea is that they use custom value capacitors, you would have to parallel a number of different capacitors to get the right value, use of a capacitance meter would be a must. One oddity is the use of a 20V regulator, I was never able to find any of these, only 18V or 24V, but now after a quick search of eBay, I see that they are available (Japanese made). The Motorola chips were unavailable for years but now with eBay you can find lots for sale!
 

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As I recall I didn't use the buffer transistors, I just removed them from the board and fed the sinal to the emitter side of the buffer transistor and removed the emitter resistors as well.
Thanks for the advices, will try without the buffer transistor as soon as the chips arrive, I'm hopping they'll be here next week. I also just thought of a good way to make sure the circuit is working properly, althought I can't buy the MC1314 and MC1315 from a local supplier, there are a copuple local vendors selling the MC1312, a week away from me considering the standard shipping method, so, with modern digital tools, such as Labview, I can feed a frequency sweep signal to MC1312 then feed it into the variblend circuit with MC1314 and MC1315, get the results, phase and magnitude plots, do the same with the discrete phaser and compare the results.

You would be better off trying to copy the S&IC's headend, it's 8-pole using TL074 op-amps. The only problem with that idea is that they use custom value capacitors, you would have to parallel a number of different capacitors to get the right value, use of a capacitance meter would be a must.
What do you mean by S&IC? Is it a decoder?
 

Sonik Wiz

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Thanks for the advices, will try without the buffer transistor as soon as the chips arrive, I'm hopping they'll be here next week. I also just thought of a good way to make sure the circuit is working properly, althought I can't buy the MC1314 and MC1315 from a local supplier, there are a copuple local vendors selling the MC1312, a week away from me considering the standard shipping method, so, with modern digital tools, such as Labview, I can feed a frequency sweep signal to MC1312 then feed it into the variblend circuit with MC1314 and MC1315, get the results, phase and magnitude plots, do the same with the discrete phaser and compare the results.



What do you mean by S&IC? Is it a decoder?
The Audionics Space and Image Composer was an advanced SQ decoder circa late 70's. It als featured a very good stereo to surround synthesis & functioned completely different than gain riding full logic.

You can read an overview here.

You can check out the schematics including the phase shift circuits Ken was referring to here.
 

par4ken

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I recently dug up the manual for the Audionics 106A decoder. It brings back a lot of memories, that's where I started really getting into quad. Sadly it doesn't have the schematic, just a lot of suggestions for installation.
 

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par4ken

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Audionics 106A with a 6-pole phaser, sounds interesting, do you happen to have the schematics or a service manual?
I don't have the schematic, however you could use the Fosgate circuit from the 101A (Thanks to furui_suterioo).

I had always planned to build an encoder by copying the Audionics 8-pole circuit. I bought 1% tolerance capacitors every chance I had. My ultimate plan was to parallel them to obtain the special values used by Audionics. Fosgate used a 6-pole circuit, also with 1% components but the capacitors are all standard values, so one could simply copy that circuit!
 

MidiMagic

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I built an 8-pole R-C phasor set in the 1970s.

And my UQ-44 passive decoder has 8-pole L-C phasors.

And I wished I had a phaser when a Starbucks delivery truck was parked for unloading in the lane for the direction I was going on a main street here last night.
 
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