clintrubber
Well-known member
Not sure to which of the many SSL-sidechain or A*P*I-Thr*st-circuit threads to add this, so let's make it yet another thread...
I've been toying around some more with the 10dB/dec filter (a.k.a. the Thr*st-filter).
While at it, I've combined this circuit with the 'variable HPF-Steffen-sidechain' for the SSL-comp.
So all in all one could now add an overelaborate sidechain to the SSL (or to whatever comp.) if one wishes to do so.
If it's actually worth while is hard to tell beforehand, so I decided to
just do it. It's simple and tweaking circuits is fun.
The Thr*st-patent kindly gave the circuit as we've seen in the relevant threads.
In addition to that, the 2*5*0*0-manual gave the in-between freq-plot: the so called medium-mode. It's a low-att. with flat mids & some hi-lift.
This will probably differ not much from the 'SSL-highpass' with some hi-boost added but to avoid getting entangled in even more elaborate variations I put it in as a non-adjustable preset and not as some additional hi-boost section glued onto the already present variable highpass. Everybody still reading ?
The rotary now has twelve positions, since I wanted to keep
the frequencies of the Steffen-circuit/Greg-PCB. One could have programmed a rotary
for only two additional positions of course, but greedy people use them all
so there are some intermediate frequencies added as well.
That might be of limited use, but one has to try before one knows.
So now we have:
#1 sidechain off
#2-#9 60 / 75 / 90 / 110 / 130 / 160 / 200 / 250 Hz first order highpass
#10 Thr*st - medium (some lo-att & some hi-boost)
#11 Thr*st - loud (10dB/dec slope)
#12 external (apart from de-essing, could anyone still think of anything for this ?! :wink: )
Overkill indeed, but you've been warned...
A possible circuit for both added filters goes like this:
Components values for the medium-thr*st-preset are tweaked to get near
the desired responses. Note that the values for the loud-preset are
slightly different from those in the patent, they're obviously rounded to the nearest standard values but that's fine, circuit response hardly differs from that for the published values.
It might have been possible to avoid additional opamps but that's not what happened.
Note the input-impedance of the loud-Thr*st-filter steadily falls from 33kOhm @ 20Hz to
some 1kOhm @ 20kHz. For both the loud&medium-filter combined the input-Z is still above 800 Ohms @ 20kHz and since the already present load is not that much I expect the preceeding 5532 will be fine.
OK, I have only drawn & simulated this contraption so far. Will be building it as soon as the highpass-PCB from Greg arrives.
So all your comments & thoughts still welcome, please shoot !
Bye,
Peter
Ah, and w.r.t. the added frequencies for the normal highpass-filter:
add caps of 180 / 120 / 82 & 56 [nF]. Maybe I add a more complete drawing later.
I've been toying around some more with the 10dB/dec filter (a.k.a. the Thr*st-filter).
While at it, I've combined this circuit with the 'variable HPF-Steffen-sidechain' for the SSL-comp.
So all in all one could now add an overelaborate sidechain to the SSL (or to whatever comp.) if one wishes to do so.
If it's actually worth while is hard to tell beforehand, so I decided to
just do it. It's simple and tweaking circuits is fun.
The Thr*st-patent kindly gave the circuit as we've seen in the relevant threads.
In addition to that, the 2*5*0*0-manual gave the in-between freq-plot: the so called medium-mode. It's a low-att. with flat mids & some hi-lift.
This will probably differ not much from the 'SSL-highpass' with some hi-boost added but to avoid getting entangled in even more elaborate variations I put it in as a non-adjustable preset and not as some additional hi-boost section glued onto the already present variable highpass. Everybody still reading ?
The rotary now has twelve positions, since I wanted to keep
the frequencies of the Steffen-circuit/Greg-PCB. One could have programmed a rotary
for only two additional positions of course, but greedy people use them all
so there are some intermediate frequencies added as well.
That might be of limited use, but one has to try before one knows.
So now we have:
#1 sidechain off
#2-#9 60 / 75 / 90 / 110 / 130 / 160 / 200 / 250 Hz first order highpass
#10 Thr*st - medium (some lo-att & some hi-boost)
#11 Thr*st - loud (10dB/dec slope)
#12 external (apart from de-essing, could anyone still think of anything for this ?! :wink: )
Overkill indeed, but you've been warned...
A possible circuit for both added filters goes like this:
Components values for the medium-thr*st-preset are tweaked to get near
the desired responses. Note that the values for the loud-preset are
slightly different from those in the patent, they're obviously rounded to the nearest standard values but that's fine, circuit response hardly differs from that for the published values.
It might have been possible to avoid additional opamps but that's not what happened.
Note the input-impedance of the loud-Thr*st-filter steadily falls from 33kOhm @ 20Hz to
some 1kOhm @ 20kHz. For both the loud&medium-filter combined the input-Z is still above 800 Ohms @ 20kHz and since the already present load is not that much I expect the preceeding 5532 will be fine.
OK, I have only drawn & simulated this contraption so far. Will be building it as soon as the highpass-PCB from Greg arrives.
So all your comments & thoughts still welcome, please shoot !
Bye,
Peter
Ah, and w.r.t. the added frequencies for the normal highpass-filter:
add caps of 180 / 120 / 82 & 56 [nF]. Maybe I add a more complete drawing later.