Simple DiodeBridge Compressor

[richiyobs]

the balanced part of the instrumAmp, as per the original single ch
i remebered Gssl solution, 1 sc x 2ch .... read a lot about every mods for better stereo tracking.....
but with this simple solution didn t noticed offset except a bit of room for Thr
will build one to check the stereo image and tracking as soon i can
also changed cap for hpf Sidechain... thanks to Heikki support i now understand how to implement variable hpf
best
richi

 

[richiyobs]

It s a simple feedback balanced sum

 

[abbey road d enfer]

It s a simple feedback balanced sum

Do you know the drawbacks of this arrangement?

 

[richiyobs]

No can you please explain?

 

[abbey road d enfer]

The problem with summing is that the amplitude of the summed signal depends on the phase relationship between the two signals; in particular, if they're out of phase, the resulting amplitude is small, so the compressor does not react.
The classic correct implementation is two detectors, one for each signal, and a combiner that retains the highest value.

 

[Script]

Said differently,, simple summing makes the SC deaf to stereo and therefore overemphasised bass frequencies (+6dB on paper, effectively maybe 5.5dB), meaning you get "too much" compression triggered by mono material (usually bass) compared to higher frequencies that tend to come more in stereo (= partially out of phase).

Technically, I'd say, summing SC before detectors is flawed, but you might still want to try it. Just don't expect the comp to compress cleanly (more like an effect, as out-of-phase=stereo slips thru more/too much) .

 

[richiyobs]

maybe with a simple stereo width circuit, is possible to decide the phase shift to apply to obtain the proper tracking, or somenthing similar?
thanks for your attention

 

[Script]

If you are looking for precision, you need two detectors.

 

[richiyobs]

how are summed LR into mono in a control room mixer, for mono check compatibility?
are they phase shifted or simply padded , to keep levels constant?
into certain phase degree there s no sum or subtraction, but in certain point -3 or + 3 even 6 ...
i read somenthing similar and so i took inspiration

 

[richiyobs]

a sort of Ms too....
but i think you all tried this way

 

[Script]

Yes, summing gives you only MID. Out-of-phase (stereo) disappears.

 

[richiyobs]

The problem with summing is that the amplitude of the summed signal depends on the phase relationship between the two signals; in particular, if they're out of phase, the resulting amplitude is small, so the compressor does not react.
The classic correct implementation is two detectors, one for each signal, and a combiner that retains the highest value.

i see that s why i asked, but it s also difficult to send out of phase material to a stereo compressor....should be damaged or wrong mixed material....

 

[richiyobs]

Yes, summing gives you only MID. Out-of-phase (stereo) disappears.

yoooo, that s what i wanted to verify
so a stereo spread and proper phase shift should work

 

[Script]

Summing doesn't see L-R. Could play with MS but it won't be "true" to program material in any way. Doesn't mean it's not interesting...

 

[richiyobs]

after 90 degree there s no sum or subt.... till 120 degree if i well rember, after that you all know calcellation

 

[richiyobs]

Summing doesn't see L-R. Could play with MS but it won't be "true" to program material in any way. Doesn't mean it's not interesting...

of course LR to simplify..... we re always reffering to 2 signals......the main difference is the panned material

 

[richiyobs]

this is what i m thinking..... saw different design to start from...
my idea is to compensate what sum is destroying in the stereo image
but really don t know if someone just tried and worked.... or just a waste of time

 

[richiyobs]

100 and 200 Hz applied to both LR or AB.... to figure out what can happens...
the output waveform can be compensated or expanded more
can be used for the purpose of summing into sidechain?
thanks for your attention
best
richi

 

[abbey road d enfer]

how are summed LR into mono in a control room mixer, for mono check compatibility?
are they phase shifted or simply padded , to keep levels constant?

Signals are usually summed, which results in a level that fluctuates in function of the Left/Right correlation ; since it creates a problem, many mixers feature a mono level control .

 

[abbey road d enfer]

my idea is to compensate what sum is destroying in the stereo image
but really don t know if someone just tried and worked.... or just a waste of time

Since it's an unpredictable variable, it's mathematically impossible.