Simple DiodeBridge Compressor

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I built a 33609 clone quite some time ago with 1N4148 in the diode bridge and found it to be very noisy. A friend who´s EE in HF engineering suggested to use 1N4153 and the result proved that he was right.
Are you still in contact with this friend? I'd really be curious to know how he came to this conclusion.
 
I recently read an interview about DBC20 by buzz audio....
they re using Schottky barrier signal diodes, and they choose this type for punchier sound....
looking at inner pics , only input tfx, the rest is opamp ,even if cheap one they can have a good distortion if pushed...
but i think you all know this device
DIODE BRIDGE COMPRESSORS - TIM FROM BUZZ AUDIO
 
found this:
Schottky diodes can achieve greater switching speeds than p–n junction diodes, making them appropriate to rectify high-frequency signals.
hoping I m not out of the way
 
Reading again the dbc20... The point four touched me!

4 - How does the adaptive ratio design of the DBC benefit how it compresses vs other compressors - what other ones is it similar to in this regard?
Tim Buzz Audio -
There are many famous compressors that operate like this, the most notable would be the Fairchild 670. Basically the thing has a wide "soft knee" characteristic. The DBC will move from a low 2:1 ratio right up to 20:1 depending on how hard you drive it....

Measuring with CMT vst, noticed that ratio is also time depending... I was worried cause I couldn't get a fixed value... So since the Sidechain design I m running it s from a vari mu... can be it be considered adaptive?
Thanks for attention
 
5 - Why did you choose the particular diodes you have in the DBC, and how different would alternate diodes make the unit sound?
Tim Buzz Audio -
We use Schottky barrier signal diodes and I chose these because they have the sound I wanted which was a bit more punchy than standard silicon diodes. Plus they also have very tight manufacturing tolerances so we do not need to match them, which saves labour and helps keeps the cost of the unit down.

Good to know
 
Even at faster setting and totally squashed...the design I m running results always smooth and no audible distortion, tested in mono of course with different program materials... But don t own the proper measurement tools to really judge
 
Regarding ratio... At max value... 17.7:1
Same settings, but lowering levels of measurement signal... Read 7.1:1
 
richiyobs, seems like the threshold is fairly high when I simulate it. seems like you could use one additional stage before the threshold to amplify the signal going into the sidechain, giving you more room to work (like you could compress lower level signals).
 
Reading again the dbc20... The point four touched me!

4 - How does the adaptive ratio design of the DBC benefit how it compresses vs other compressors - what other ones is it similar to in this regard?
Tim Buzz Audio -
There are many famous compressors that operate like this, the most notable would be the Fairchild 670. Basically the thing has a wide "soft knee" characteristic. The DBC will move from a low 2:1 ratio right up to 20:1 depending on how hard you drive it....
That is a quite common feature of feedback compressors. Only feedforward compressors (which tend to be mostly VCA-based) do not behave like that.
Measuring with CMT vst, noticed that ratio is also time depending... I was worried cause I couldn't get a fixed value... So since the Sidechain design I m running it s from a vari mu... can be it be considered adaptive?
It's not really the structure of the side-chain that matters, it's how it is connected to the signal chain that makes a difference.
Since the side-chain samples the signal after the diode bridge, it's a feedback topology, so, yes, it has this variable-ratio characteristics.
 
That is a quite common feature of feedback compressors. Only feedforward compressors (which tend to be mostly VCA-based) do not behave like that.

It's not really the structure of the side-chain that matters, it's how it is connected to the signal chain that makes a difference.
Since the side-chain samples the signal after the diode bridge, it's a feedback topology, so, yes, it has this variable-ratio characteristics.
Wow now I see!
Thank you so much
 
richiyobs, seems like the threshold is fairly high when I simulate it. seems like you could use one additional stage before the threshold to amplify the signal going into the sidechain, giving you more room to work (like you could compress lower level signals).
I could save your time... i got the LTspice asc
i could attach, it contains all the suggestions i received and also the out amp to check
 
here it is....
i m trying to implement autorelease, following the rule of thumb just learned...
just wire AUTO
 

Attachments

  • dsB_meter_ampOut_Autoset.asc.zip
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