Interesting phase shifting circuits

[scifi]

I've tried to read those SQ matrix patents (briefly), but don't really understand them too well. Anyone that's interested in phase shifting circuits for use in matrix quadraphonic systems as well as electronic effects might be interested in these patents I found. US 4122364 is listed on the label on the bottom of the Multivox LD-2 Little David http://www.effectsdatabase.com/model/multivox/ld2


http://www.google.com/patents?q=4122364&btnG=Search+Patents

US 4122364
http://www.google.com/patents?id=95...urce=gbs_overview_r&cad=0#v=onepage&q&f=false

US 5877643
http://www.google.com/patents?id=nP...urce=gbs_overview_r&cad=0#v=onepage&q&f=false

 

[MidiMagic]

The first two are for phase pedals for guitars, not quadraphonics.

I designed a few phase shift circuits for quad myself. One used transistors in cascaded phase shift stages. The other set is in my passive speaker matrix SQ decoder.

 

[tejanoboy]

MidiMagic, would you consider posting a schematic for your passive speaker SQ decoder? I can see simple passive decoding of QS or DPL-II , but SQ?
Broadband 90* phase shifting at speaker level? You REALLY have my curiosity at full throttle! I saw a device from a jukebox that was supposed to do SQ at speaker level, maybe the same thing?
Thanks!
TB

 

[MidiMagic]

This might take some time. The schematic is on 10 legal size sheets.

I used multiple LC circuits (instead of RC circuits, to avoid resistive loss) and center-tapped 32 ohm transformers to make Psi-0, Psi+90, and Psi-90 circuits. Then I used switching and resistor networks to make QS as well as SQ decoding.

It had only a 3-dB insertion power loss.

It actually has 12 different decoding selections:

- QS
- SQ
- EV 4*
- Dynaquad*
- EV Universal
- UQ Equal separation matrix
- Compatiquad (halfway between QS and SQ, for mixing quad records on a record changer)
- UMX (basic matrix - face the left front speaker instead of directly to the front to listen to this)
- Variable parameter QS
- Variable parameter SQ
- Variable parameter basic matrix
- Variable parameter Compatiquad

* Bypasses the phase shifters.

It also has a passive separation enhancement circuit.

I could probably never build another one, because I got parts from a huge selection of adjustable coils the local high school was getting rid of when they closed the electronics classroom. I paid $3 for the box of coils at an auction. I later tried to order similar coils, and the company wanted a minimum 1000 piece order to supply them.