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SANSUI QSD-2 HUMMMM

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maspadaro

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quadsearcher

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First I must have missed it, so thank you, but its more of a service manual though and does not give me how to operate it. But since I am not electronic savvy I am not sure if the outputs it mentions is for Phono in to stereo or line out. 730MV rated I assume it refers to Phono and not to Aux.
Incorrect. 730mV refers to Aux/Line Level. There is no phono input on this unit, no phono preamp.
The QSD-2 would be used in a tape loop of a quad receiver. Its outputs would go to LF, RF, LR, RR. It is a line level unit, not phono level at all.
Matrix decoders work at line level, at least the ones I've read about here. (CD-4 demodulators, however, accept only MM cartridge level).
If a phono (no preamp, just moving-magnet cartridge to RCAs to input of decoder) is plugged straight into a decoder, the audio level would be very low, EQ would be wrong (tinny), decoding would be poor-to-none, and I would expect background noise (hum and hiss).
MM cartridges put out around 5mV.
Line level minimum is about 740mv nominal (around 1volt typical). QSD-2 accepts as low as 130mV and as high as 3volts, as seen in 1. Specifications of the service manual.
So, you see, sending a signal approx. 20 (edit: no, 200?) times too low would be outside of operating parameters of the unit and it would not function as intended.
To use QSD-2 with two stereos, it gets confusing, but assuming they both have tape loops, then phono would go to phono IN on one unit, Tape OUT from that stereo would go to input of QSD-2, Front OUTS from decoder go to Tape IN of one stereo, and Rear OUTS from decoder go to Tape IN of second stereo.
This is all assuming you have a traditional old-school turntable with NO internal preamp.
 
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quadsearcher

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I looked for an owner's manual and could not find an online scan. If there is an original for sale, it is because it has value to a seller who wants to flip the unit, or to an owner/collector who is a completist.
There's no big mystery needing an owner's manual. 2 channel line in, 4 channel line out.
 

furui_suterioo

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You could connect the QSD the way that quadsearcher describes above, but if you want the cd-4 demodulator at the same time, connect the turntable directly to the demodulator, connect the demodulator's "2CH DIRECT" to a PHONO input on one of the receivers, and the demodulator's 4ch outputs to the tape monitors.
 

maspadaro

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My last post did not happened , so will try to remember what I said. Thank you just saved it. But its a service manual, and I was looking to see the operation instruction and connections. The weird part was that the 4 channel output F\R worked into the Phono in on my 2 stereos. The 4 channel outputs usually goes to either AUX or Tape loop on the 2 stereos. No quad receiver or AMP have phono inputs for Front\Rear. Why would the QSD-2 output go to Phono instead of AUX.
Incorrect. 730mV refers to Aux/Line Level. There is no phono input on this unit, no phono preamp.
The QSD-2 would be used in a tape loop of a quad receiver. Its outputs would go to LF, RF, LR, RR. It is a line level unit, not phono level at all.
Matrix decoders work at line level, at least the ones I've read about here. (CD-4 demodulators, however, accept only MM cartridge level).
If a phono (no preamp, just moving-magnet cartridge to RCAs to input of decoder) is plugged straight into a decoder, the audio level would be very low, EQ would be wrong (tinny), decoding would be poor-to-none, and I would expect background noise (hum and hiss).
MM cartridges put out around 5mV.
Line level minimum is about 740mv nominal (around 1volt typical). QSD-2 accepts as low as 130mV and as high as 3volts, as seen in 1. Specifications of the service manual.
So, you see, sending a signal approx. 20 (edit: no, 200?) times too low would be outside of operating parameters of the unit and it would not function as intended.
To use QSD-2 with two stereos, it gets confusing, but assuming they both have tape loops, then phono would go to phono IN on one unit, Tape OUT from that stereo would go to input of QSD-2, Front OUTS from decoder go to Tape IN of one stereo, and Rear OUTS from decoder go to Tape IN of second stereo.
This is all assuming you have a traditional old-school turntable with NO internal preamp.
So for what you are telling me the TT doesn't go directly to the QSD-2? it goes to the stereo then out to the QSD-2 Input via tape out ... Next question, which QSD-2 input?
WE have the tape loop "rec\play" and also an "input" connection.
This is the why I needed the operational manual to understand the connections.
Regards,
Miguel
 

furui_suterioo

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Why would the QSD-2 output go to Phono instead of AUX.
It doesn't:
The QSD-2 would be used in a tape loop of a quad receiver. Its outputs would go to LF, RF, LR, RR. It is a line level unit, not phono level at all.
Front OUTS from decoder go to Tape IN of one stereo, and Rear OUTS from decoder go to Tape IN of second stereo.



So for what you are telling me the TT doesn't go directly to the QSD-2? it goes to the stereo then out to the QSD-2 Input via tape out.
Correct.
 

quadsearcher

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My last post did not happened , so will try to remember what I said. Thank you just saved it. But its a service manual, and I was looking to see the operation instruction and connections. The weird part was that the 4 channel output F\R worked into the Phono in on my 2 stereos. The 4 channel outputs usually goes to either AUX or Tape loop on the 2 stereos. No quad receiver or AMP have phono inputs for Front\Rear. Why would the QSD-2 output go to Phono instead of AUX.

So for what you are telling me the TT doesn't go directly to the QSD-2? it goes to the stereo then out to the QSD-2 Input via tape out ... Next question, which QSD-2 input?
WE have the tape loop "rec\play" and also an "input" connection.
This is the why I needed the operational manual to understand the connections.
Regards,
Miguel
Yes.
"Input" connection on QSD-2
accepts L and R from Tape Out of the first receiver in one of my previous posts (first receiver = the unit that has the phono turntable plugged into the Phono input).
Yes, an owner's manual would be handy. It is hard for me to describe in words what could better be seen as a picture. This might not format correctly
on the screen:

TT--->Phono IN, (Stereo 1), Tape OUT,--->IN (QSD-2) OUT---|
FR, FL |------->Tape IN (Stereo 1) Front Speakers
RL, RR |------->Tape IN (Stereo 2) Rear Speakers

I'd start there, and get familiar with the separation of sounds that happens.
furui_suterioo's CD-4 integration in post #24 of this thread would be a separate step (for me, anyway, I try to take it a step at a time).
 

maspadaro

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OK Update: SUCCESS!!!

I now need a pre-check flight sheet to know which switches to flip for each source .
Was not an easy set up with the equipment shown in the picture.
Part of the issue was that I have an EQ\Reverb mic\U-24 program selector in between all the connections which added to the complexity.
The separation was almost there, but I will need to refine it. Was a bit surprise and really no hummmm.

Again thank you everyone, I almost gave up!!!!

Regards,
Miguel
 

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par4ken

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gvl_guy

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OK Update: SUCCESS!!!

I now need a pre-check flight sheet to know which switches to flip for each source .
Was not an easy set up with the equipment shown in the picture.
Part of the issue was that I have an EQ\Reverb mic\U-24 program selector in between all the connections which added to the complexity.
The separation was almost there, but I will need to refine it. Was a bit surprise and really no hummmm.

Again thank you everyone, I almost gave up!!!!

Regards,
Miguel
Wow. That's a beautiful setup.
 
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