[build] Steffen's GSSL High Pass Filter Documentation

[digichild]

[quote author="Greg"]No, there's no set threshold calibration. It's really just a set to taste pot. What I did was use the compressor a good bit, then set my typical compression threshold to around 12 o'clock. I felt this gave me a much better range.

If you want it to be same as stock, set the pot to 11K. Or you could also just build the PCB, send it a test tone, and tweak the pot until unity is achieved.[/quote]

so with this rv1 pot on the board i am able to adjust the treshold,and i dont have to worry about this thread http://www.groupdiy.com/index.php?topic=2418&highlight=ssl+sidechain anymore?

 

[Steffen]

[quote author="digichild"][quote author="Greg"]No, there's no set threshold calibration. It's really just a set to taste pot. What I did was use the compressor a good bit, then set my typical compression threshold to around 12 o'clock. I felt this gave me a much better range.

If you want it to be same as stock, set the pot to 11K. Or you could also just build the PCB, send it a test tone, and tweak the pot until unity is achieved.[/quote]

so with this rv1 pot on the board i am able to adjust the treshold,and i dont have to worry about this thread http://www.groupdiy.com/index.php?topic=2418&highlight=ssl+sidechain anymore?[/quote]

yepp!

prösterchen! :grin:

steff

 

[digichild]

wow-that was fast-thanks steffen-i think for tonight i can close down the ssl...i am very exited about this sidechainboard and the improvements with the treshold and the ratio


hehehe...i made a first test today with my new clone and it worked from the beginning...i am happy :green:

 

[mathflan]

I'm not sure what the sidechain high pass doing...

The High pass filter is just for the sidechain Inputs or It's for the Normal inputs too?

 

[Guest]

[quote author="mathflan"]I'm not sure what the sidechain high pass doing...

The High pass filter is just for the sidechain Inputs or It's for the Normal inputs too?[/quote]
Thats what got me confused to begin with when I looked at the SSL
Somebody please correct me if I am wrong and I will edit the post.

There is no external sidechain in the SSL
The word "sidechain" is used as a function of what is electronically happening inside the compressor and not what we use in musician/studio terminolology as patch a sidechain into the compressor for ducking etc.
A portion of the original signal is used to detrmine how much work the compressor should do - this is the "internal" sidechain
The HPF filter for the internal "sidechain" is to stop the compressor aggressively compressing audio that has a lot of "oomph" in the low audio spectrum
So if we HPF the signal being monitored by the compressor via the internal sidechain - it will not over compress on bass heavy mixes

A heavy bass drum will cause the entire mix to be compressed
By using the HPF sidechain we can avoid this happening

 

[mathflan]

Ok thanks a lot

it's more clear now.

 

[Purusha]

I got the Greg's PCBs for Stephen's HP filter. Can someone just check a little bit if I got it right how to connect this properly to the main PCB and rotary? I checked the PDF file with sidechain modification. First I remove both 47K, this is clear, than I connect the OUT, L, R on main PCB with OUT, L, R on the SC PCB, this should be also clear. Then we have the SND as send and RET as return for the external SC option, this is also very clear. OK, then we have the SW and the GND on SC PCB which I am not sure where to connect on my 1/12 rotary. I would say the SW goes to the middle pin on the rotary and the GND goes to the ground pin on the external 1/4 stereo connector?

One more thing. How do you connect properly the bypass position on the 1/12 rotary? Do I need to connect it at all?

 

[Greg]

The SW goes to your switch pole, which is in the middle on a Lorlin rotary. The GND goes to your star ground. For the bypass position on the high pass filter, there's a pad number "1" in the middle of the board. Take this point to the first position on your rotary.

Hope this is clear. :thumb:

 

[Purusha]

Did not understood the "star ground" meaning. You mean the chasiss ground?

....6 goes to rotary for external?

Where do you take the +/-15V from the main PCB? There is some point where it says +15 -15 on the main PCB, is this the spot?

 

[Greg]

Yes, star ground is chassis ground.

Yes, 6 goes rotary for external sidechain.

Check the PDF I modified in the first post of this thread. I show a good spot to pull the +/-15V.

 

[Purusha]

OK. It's all clear now. Thanks Greg! :thumb:

 

[Twin-x]

after a lot of bugs i finally got my compressor working (thx Gyraf for the tips)

anyway i have now arrived at Gregs addon.

is the return on this thing supposed to give me a clean signal of the sound i put in? I hear nothing.

It does however do compress on the signal i put in (send) but i hear nothing on the return (very very faint). (It may sound very stupid but this new to me)

 

[Greg]

The send and return are to be used for a typical external sidechain.

 

[fucanay]

I don't "need" to hook up the external right? I was planning on leaving the switch as 5 positions and leaving that disconnected. I need to do some chassis work and then I'll get these things installed.

I hate chassis work. I have 2 G1176s and 2 GSSLs stuffed and mostly wired but I'm dragging on the chassis stuff. I guess it would help if I had a proper metal shop set up. Maybe I'll work on that this week.

Matt

 

[Greg]

Yes, you can just omit the external is you don't want it.

 

[khstudio]

I would like to add that I use the sidechain filter all the time... it's a great addition to the GSSL :thumb:

Thanks again for the boards Greg.

Kevin

 

[byoung]

Quick question about using the sidechain board. It is my understanding that it is now recommended on Gyrafs site to put a 47K resistor on one leg of the threshold pot to reduce it's sensitivity. Should I still add this resistor or does the trim pot on the sidechain board handle the same sensitivity reduction if set properly?

 

[Greg]

I just use the trim pot on the board...

 

[caps]

Guys,

Any chance Id get away with 50V monolythic caps instead of 100V ones for the HPF, 22pf?

For the life of me. you cant find 100V ones round these parts...

 

[gyraf]

..as the nominal supply voltages are +/-15V, anything above 30V will do fine..