Gain Riding Logic - did it ever sound good?

[kfbkfb]

Found the Dolby Surround info (monitor surround mix thru encode + decode):
https://www.soundonsound.com/techniques/surround-sound-explained-part-2
I recently went back to listening to DS encoded content with DPL rather than DPL2 movie, original DPL has better imaging, probably due to the reason explained in the above link.


Kirk Bayne

 

[ar surround]

Found the Dolby Surround info (monitor surround mix thru encode + decode):
https://www.soundonsound.com/techniques/surround-sound-explained-part-2
I recently went back to listening to DS encoded content with DPL rather than DPL2 movie, original DPL has better imaging, probably due to the reason explained in the above link.


Kirk Bayne

Very interesting series, but long. I hope to get around to reading it in due time. (But I also need to get around to reading Moby Dick. )

 

[jaybird100]

Wives still would have been, "Oh no you don't" to guys trying to put a full blown quad system in their living rooms.



Doug

Isn't it interesting how wives take full possession of the living room, forgetting that "hubby" lives there, too?

 

[ar surround]

Isn't it interesting how wives take full possession of the living room, forgetting that "hubby" lives there, too?

That would be an improvement if it was full possession of only the living room. My wife has full possession of the entire house except for the basement which is mine. We agreed to this when we bought the house and I am grateful for these T&Cs.

 

[Doug G.]

Isn't it interesting how wives take full possession of the living room, forgetting that "hubby" lives there, too?

Well. bless their hearts, they want the living room to be nice for "company". When I was a kid, the lady across the street wouldn't even let us IN the living room.

Doug

 

[DuncanS]

Well. bless their hearts, they want the living room to be nice for "company". When I was a kid, the lady across the street wouldn't even let us IN the living room.

Doug

I remember regularly stopping at a Great Aunt & Uncle's in Doncaster on our holiday trips back up to Scotland, and their front room/lounge/parlour was only for special occasions ....... so us kids were rarely let in it!

 

[jaybird100]

That would be an improvement if it was full possession of only the living room. My wife has full possession of the entire house except for the basement which is mine. We agreed to this when we bought the house and I am grateful for these T&Cs.

Basement... must be nice! We can't have 'em here. We'd hit water if we tried.

 

[MidiMagic]

The Sony SQD-1000 decoder, which was the first SQ decoder I bought, used gain riding to try to enhance separation, but the "pumping" effect was highly annoying. Sony referred to the method as "partial logic". It was a valiant first attempt, but when you see how far any matrix decoding has progressed (the Surround Master comes to mind), well, it makes me wonder what would have been had decoding at that level been available back in the early 70's.

We forget that the idea that quad would sell well came from the fact that the R4 decks were flying off the shelves. As a repairman, most of the R4 decks I worked on were in homebrew recording studios, not in 4-channel stereos.
.
The other stuff didn't sell as well, so the companies thought people wanted discrete. So they all went CD-4 and lost money.
.
Pumping was really bad if you were into classical music with ambience in the back. It kept changing levels.

 

[MidiMagic]

Is that a measured result or subjective? I have noticed (subjectively) a reduction of bass with a number of different decoders. The Audionics S&IC has no such bass loss, what goes in comes out! I replaced the output coupling caps in my QSD-1, changing from 1µF to 10µF, the same as in the Composer. The (subjective) bass response is now is about the same as with the Composer. So do most decoders use too small an output capacitor? You wouldn't think so unless the unit is driving a very low impedance.

Actually they lowered the input impedance to amplifiers. The ones I was using when I started with quad had a 100K input impedance. I have seen newer ones with 10K or 4.7K input impedance. That would load down the output capacitor at very low frequencies.

 

[MidiMagic]

The thing I remember most about when I first read about SQ was the "helical motion" aspect of groove modulation and, at first, trying to imagine a stylus moving in a helical way which, of course, a stylus in a stereo cartridge cannot do.

Doug

Yes it can. The tip just moves in a circle around the center of the groove modulation.

 

[par4ken]

We forget that the idea that quad would sell well came from the fact that the R4 decks were flying off the shelves. As a repairman, most of the R4 decks I worked on were in homebrew recording studios, not in 4-channel stereos.
.
The other stuff didn't sell as well, so the companies thought people wanted discrete. So they all went CD-4 and lost money.
.
Pumping was really bad if you were into classical music with ambience in the back. It kept changing levels.

My SQD-1000 was an eBay bargain purchased years ago. After reading jaybird's post I pulled it out. I thought that it was just a "basic" decoder but it turns out that it's "logic" is vari-blend across the front and back. It actually sounds rather nice and I don't hear any "pumping". Gain riding logic pumps the volume up and down, if set up too aggressively the pumping action is audible. This unit does not pump. I'm sure that in a large room the SQD-1000 would be unimpressive just like the Sansui QS-1 is but in a small room both decoders sound very good indeed!

Much more recently I picked up a Pioneer QD-210 for little more than the cost of shipping. That unit operates similarly to the Sony unit but as I recall it only blends the back channels and does so much more aggressively which does cause anomalies. I'm very impressed with the Pioneers build quality but not with it's sound!

 

[MidiMagic]

I still think about the Hafler Diamond and how it really didn't need separation enhancement.

The two quad separations that matter most to most people are front center to back center and left front to right front.

The Hafler diamond's two maximum separations were front center to back center and left to right.

 

[jaybird100]

My SQD-1000 was an eBay bargain purchased years ago. After reading jaybird's post I pulled it out. I thought that it was just a "basic" decoder but it turns out that it's "logic" is vari-blend across the front and back. It actually sounds rather nice and I don't hear any "pumping". Gain riding logic pumps the volume up and down, if set up too aggressively the pumping action is audible. This unit does not pump. I'm sure that in a large room the SQD-1000 would be unimpressive just like the Sansui QS-1 is but in a small room both decoders sound very good indeed!

Much more recently I picked up a Pioneer QD-210 for little more than the cost of shipping. That unit operates similarly to the Sony unit but as I recall it only blends the back channels and does so much more aggressively which does cause anomalies. I'm very impressed with the Pioneers build quality but not with it's sound!

I can tell you there were very obvious shifts in gain, especially in the rear channels, regardless of the genre of the music. You apparently had a different experience than I did, for reasons I don't know.

 

[par4ken]

I can tell you there were very obvious shifts in gain, especially in the rear channels, regardless of the genre of the music. You apparently had a different experience than I did, for reasons I don't know.

The blending action might cause apparent level shifts of the centered vocals only, but I didn't notice that. The maximum front to back (center) separation is only about 9dB at best. Half that number comes from the front blend the other half from the rear blend. They refer to it as front to back logic but it's not really. Later decoders with front to back logic did shift levels up and down. I remember them (F-B logic) being heavily criticised. Full logic does the same but detects corner signals as well as front to back.

 

[jaybird100]

The blending action might cause apparent level shifts of the centered vocals only, but I didn't notice that. The maximum front to back (center) separation is only about 9dB at best. Half that number comes from the front blend the other half from the rear blend. They refer to it as front to back logic but it's not really. Later decoders with front to back logic did shift levels up and down. I remember them (F-B logic) being heavily criticised. Full logic does the same but detects corner signals as well as front to back.

That's why we're fortunate, today, to have a decoder like the SM. No pumping, on either SQ or Involve (QS). One thing I discovered, with the 1000, was the effect you got from stereo records if you pushed the mono button on the rear amp. It's similar to a Hafler circuit, but where you have more control of the rear level.