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Anyone have 'stereo blend' control experience?

I'm interested in any details anyone may be able to provide concerning 'stereo blend' controls, for progressivly reducing a 2-channel signal down from full separation towards a mono blend, presumably through cross-mixing.

What older equipment might you be familiar with that featured such a contol? Did any incorporate a 'defeat' provision, or was the control always in the circuit? If you ever used one, how well do you remember it working?

Do you have any electrical design knowledge of previous implementations of this idea, or suggestions on how to make one? What kinds of parts were used in any older designs you may have seen? Do you know of any schematics?

I realize this probably was a pretty obscure feature even in its day, but maybe some of you more, ahem, experienced hands out there know what it is I'm talking about. TIA for any info!
zaikesman
onhwy61's avatar
onhwy61
5,137 posts
 
Don't know much about the older equipment, but stereo width controls are common in modern digital processors. Take a look at t.c. electronic Finalizer or the Drawmer 2496. Hi-end digital reverbs (Lexicon & t.c. electronics) also have this feature. A frequent use is to fatten up mono synthesizer patches.
mcfarland
356 posts
 
I have a Dyna PAT4 as well as an old AR tuner, both of which feature Stereo-Blend swithcable (not variable) controls. This switch on my tuner (which still works perfectly) blends the high frequency signals to mono operation, which can reduce noise on FM fringe reception broadcasting and it does work. On the PAT 4, either the left, right, or both channels may be switched to mono operation. I rarely used these switches except to experiment. There is also a high frequency filter, that variable switches a frequency "roll-off" @ 15 khz, 10 khz, or 7.5 khz. This switch is useful in getting rid of "tape-hiss", noisy records, or any high frequency unwanted noise. I have frequently used the 15 khz roll-off with good results. Hope the helps you. Good Listening.
bob_bundus
1,834 posts
 
I guess that Zaik wants to blend the entire freq. spectrum at variable ratio's, not just hi-blend & not pure mono, but somewhere in-between & adjustable. A L/R analog mixer would be needed with control of the amount of L signal emerging from R (R + some left) channel and conversely, control of the amount of R signal emerging from L (L + some right) channel. Anyone aware of a design like that? Perhaps a custom designer such as Andy Bartha could fabricate such a device?
zaikesman OP
3,017 posts
 
Correct, Bob B., and I'm pretty sure some older preamps or receivers featured such a control, like the Dyna's and AR mentioned. Onhwy61, I'm not looking to digitize anything for this, just to get somewhere in between full stereo and full mono when listening to 60's recordings with unatural panning extremes. Any more citings of gear that had this feature would be great.
zorpman
87 posts
 
The Apt Holman preamp (great 70s gear available on Ebay)has the best stereo blend control I have seen. Complete infinity variable blend/separation of channels. A real eye opener.
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