when compression turns to Upward

[richiyobs]

Hi folks,
i m having this problem.... or a cool feature , really don t know!
building a stero diode bridgecomp for a friend of mine. At first turn on noticed that CV out is higher respect to my first proto
on proto i get 568mV, now 880mv as minimum value, can t lower with bias trimmer
the unit works , but as you set release faster than 100ms i m having upward compression.... on drums it s cool!
but for some material seems to produce a sort of pumpin fx
respect to the proto the only difference is i m using lorlin for controls pot
so went back to simulation to check and i get the attached pics.... it s a lot i don t play with that device and now i m so confused
what can cause this behavior? higher signal at sidechain Input?

thanks for your attention

 

[richiyobs]

found!
R31 at sidechain input on the attached file
running different updates placed a wrong resistor value, so rising over 1k according to that opa buffer i get upward compression
i can put a pot and play with it..... is this possible or it s a mess

 

[Script]

A diode bridge transient shaper ? It would certainly sound cool as a project/product...

Can't be of much help technically, mess or not, but beefing up the tail is like the opposite of squashing the attack -- nay, actually somewhat the same. But maybe there's also distortion playing into it?

Used sparingly, how does it sound on program material ? And how controllable is it ?

 

[abbey road d enfer]

Hi folks,
i m having this problem.... or a cool feature , really don t know!
building a stero diode bridgecomp for a friend of mine. At first turn on noticed that CV out is higher respect to my first proto
on proto i get 568mV, now 880mv as minimum value, can t lower with bias trimmer
the unit works , but as you set release faster than 100ms i m having upward compression.... on drums it s cool!

I don't see anything but normal here for a feedback compressor (side-chain grabs output).
The initial transient passes without compression, because the side-chain is not quick enough to capture it, then gain reduction happens producing the dip, and after a little while, since the output level has decreased, the side-chain requires less compression.

but for some material seems to produce a sort of pumpin fx

That's a quite known issue with FB compressors.

respect to the proto the only difference is i m using lorlin for controls pot

It is certainly not a cause for a change of behaviour. Probably you had not noticed it before, because you didn't put the compressor in similar situation, or with a type of program that is less prone to that.

 

[richiyobs]

A diode bridge transient shaper ? It would certainly sound cool as a project/product...

Can't be of much help technically, mess or not, but beefing up the tail is like the opposite of squashing the attack -- nay, actually somewhat the same. But maybe there's also distortion playing into it?

Used sparingly, how does it sound on program material ? And how controllable is it ?

well good to know....
+4dBu is fine as input level except finalized material, there with more than 3dB of reduction at extreme settings, yes there s distortion!
on drum is great! specially room mics.... the fastest setting is incredible cause you aspect to loose low end , instead is there and in your face with longer tails
for sure a mix tool to have fun in that modality... as you said it s a beefy one
but as i finish this build i ll try to do A/B test to upload
best

 

[abbey road d enfer]

found!
R31 at sidechain input on the attached file
running different updates placed a wrong resistor value, so rising over 1k according to that opa buffer i get upward compression

Not upward compression; it is similar to expansion, but yet not the same. It's jusr simply known as pumping; many DJ's want that.
Wrong value in R31 changed the threshold, so made it probably acting harder.

 

[richiyobs]

Not upward compression; it is similar to expansion, but yet not the same. It's jusr simply known as pumping; many DJ's want that.
Wrong value in R31 changed the threshold, so made it probably acting harder.

Thanks for clarify!
and yes i didn t noticed early... even on simulation
slowly i m learning , a bit experienced

 

[richiyobs]

Maybe understood the role of that wrong resistor... Like high and low threshold control...
Sorry for troubling and thanks again for your support
Best