SSL 4K channel dynamics. (And more in future). PCB's/kits: Available!

[jasonallenh]

i used a linear pot for the threshold and ration, log and pull switch for the attack/release

I would verify all your part values first and then try the calibration procedure. This thing works well from the first power up if you've gotten the values and placements correct. Which RMS detector are you using?

 

[seancook]

yeh thats probably the best way forward

i used the ad chip, i may also try populating the that chip section and see if its still erratic to rule that out

 

[Majestic12]

Lunchboxes / 500 rack power supplies always  run on +-16V so it is obvious that you measure that voltage instead of +-18V

 

[Majestic12]

The schematic sais +-18V because that's the voltage that is used in SSL consoles. Igor just did not change it when drawing the new schematic from the original one.

There is no voltage multiplier whatsoever in the circuit so you'll never get +-18V on the rails when you only feed in 16V from the power supply.

It is no problem at all to have 16V instead of 18V. The only thing that changes is that you have slightly less headroom.

 

[Tom1349]

Hello

Just fished 1 4KCC, I'm in calibration now,

jasonallenh posted on page 7 a calibration method but he keeps say "Set the compressor to the settings specified in the documents"

or "Set the expander settings to those specified in the SSL docs."

Can any one say what are these "setting" ? i now that it is the position of ratio, threshold, range etc....

Thanks.

 

[Tom1349]

Hi

Ok found it here :

https://docslide.net/documents/611-calibration.html

Cheers

 

[ramshackles]

Thanks for that link.

I have added the PDF here:
http://ramshacklerecording.com/projects/4kcc/

 

[mattmartin831]

Does this build allow for switching between fast and slow attack modes like in the SSL channel plugin?

 

[stylesforfree]

Is there a BOM for this somwhere? I cant find one.

 

[Ilya]

Is the original archive with Igors docs available anywhere?

 

[ramshackles]

https://drive.google.com/file/d/1DfL79vHjS-A_nVupGeDZOyc97u0VPD_9/view?usp=sharing

 

[Ilya]

Thanks a ton!

 

[ramshackles]

Hello 4KCC builders.
I am putting together sources for various parts. What have you guys been using in place of the BC214 transistor (TR4)?

Some possibilities I have been looking at:

MPSA56 (Reverse pinout)
BC559BTA
BC560CTA
PN3638A
2N5089

 

[Ilya]

I've successfuly used MPSA56. But in the other circuit. Hope this is helpful.

 

[ramshackles]

Thanks
I swapped one in and it works fine.

Should have a parts kit coming soon.

 

[ramshackles]

Hi 4KCC builders.
Full BOM available here:
https://octopart.com/bom-tool/lJ36mjlB

Parts kit with everything (Except metal work and knobs) is now available from ramshackleaudio.com

 

[Gertius]

This has turned out to be wrong information. The wiper of the compressor release pot is rightly shown to be at 0V. Sorry!

Hi guys,
while working on making my Danfield 716a clones closer to the original, I´ve found the information, given by Andy Millar, that the wiper of the compressor release pot is not supposed to be connected to 0V ground, but to -5V instead (pin 23 of card connector). Please see also this thread: http://forum.sslmixed.com/index.php?topic=1269.0

It is wrongly shown in the original schematic and also in the 4KCC schematic.

I´ve changed this recently to -5V on one of my Danfields, and I think it made the compressor react even more similar to the original. Unfortunately I messed up the "before" recordings so I can only compare from memory right now, but I will investigate this further with my other Danfield units.

 

[moamps]

.....I´ve found the information, given by Andy Millar, that the wiper of the compressor release pot is not supposed to be connected to 0V ground, but to -5V instead (pin 23 of card connector). .

If pin 23 is at -5V, C6 22uF capacitor can be reversely polarized with the pot.
Here is the schematic I have for the reference.

 

[moamps]

And here is older version which is little bit different.
Btw, thanks for the link of whole manual.

 

[Gertius]

Hi moamps,
thanks for your input!
I have now traced this on my original SSL channel that is my sound reference. You are right, the compressor release pot is connected to 0V and not -5V like stated before. It seems though that the pin 23 is wrongly depicted in the schematic, as pin 23 does have -5V.

Sorry for spreading wrong information! I have corrected my post above.

Oh, and also thanks for sharing the old revision of the 82e10 schematic. Very interesting to look at! Here the -5V would not be detrimental to the capacitor, maybe Andy was referring to that schematic from memory.

Cheers!