JAY X

SSL 242 filters question
« on: December 26, 2020, 04:24:13 AM »
Hi!

¡¡Happy holydays!!

I'm trying to build SSL filters HPF and LPF. And i think i confused myself a bit. For instance, in the schematic RV6 i thought it was a regular potentiometer, but it seems a preset pot. RV6 5k linear i suppose. This is to set the LF filter corner. RV5 is also a preset pot, to be set to match R56 300R.

And, for the triple gang reverse log 47k i know audiomaintenance has them. But i would like to find a smaller one even if it is 50K. ¿does it make much difference 47k vs 50k?, maybe just a bit more attenuation.

¡¡Happy holydays and stay Safe!!

Jay x


abbey road d enfer

Re: SSL 242 filters question
« Reply #1 on: December 26, 2020, 08:45:53 AM »
Hi!

¡¡Happy holydays!!

I'm trying to build SSL filters HPF and LPF. And i think i confused myself a bit. For instance, in the schematic RV6 i thought it was a regular potentiometer, but it seems a preset pot. RV6 5k linear i suppose. This is to set the LF filter corner. RV5 is also a preset pot, to be set to match R56 300R.

And, for the triple gang reverse log 47k i know audiomaintenance has them. But i would like to find a smaller one even if it is 50K. ¿does it make much difference 47k vs 50k?, maybe just a bit more attenuation.

¡¡Happy holydays and stay Safe!!

Jay x
there's no difference between a 47k and a 50k pot. E3 progression (European) is 1, 2.2, 4.7 and multiples. Far East suppliers use 1, 2, 5 and multiples. The actual tolerance on pots is such that a pot marked 50k would be anything between 40 and 60k, and one marked 47k could be anything between 38 and 57k.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

JAY X

Re: SSL 242 filters question
« Reply #2 on: December 26, 2020, 11:11:23 AM »
Hi!

Ok for the pot tolerance!! Always to have in mind!! ;D

And for the RV6 pot? It is a preset pot right?, so for these filters, the only controls on the front panel would be the frequency? no gain.

Jay x

JAY X

Re: SSL 242 filters question
« Reply #3 on: December 26, 2020, 11:43:35 AM »
Hi!

Well, after some research, i think yes, the only controls of both these filters is frequency, like in the SSL x rack preamp module. So the RV6 5k preset is to set the -3db LPF corner frequency.

Jay x

abbey road d enfer

Re: SSL 242 filters question
« Reply #4 on: December 26, 2020, 04:55:31 PM »
Hi!

Well, after some research, i think yes, the only controls of both these filters is frequency,
No other control is expected for a HPF.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

JAY X

Re: SSL 242 filters question
« Reply #5 on: January 11, 2021, 02:32:35 PM »
Hi!

Still studying the schematics... ::) In these filters, the frequency is adjusted clockwise. ¿correct?, so for the LPF the lowest frequency is when the potentiometer is fully anticlockwise so the B and C sections wipers go towards ground. The A section rotation is not signaled, but if it is wired as the other sections..., clockwise rotation is wired towards the R64 10R output resistor...¿right? ???

Jay x

sr1200

Re: SSL 242 filters question
« Reply #6 on: January 11, 2021, 04:48:44 PM »
well, you would want to bring your HPF from "nothing" and up to whatever the max rage is for.  The LPF you would want the opposite.  Start at the max and turn down to the minimum.
MEI Studio - Long Island, NY: http://www.meirecords.com

abbey road d enfer

Re: SSL 242 filters question
« Reply #7 on: January 11, 2021, 05:07:59 PM »
Hi!

Still studying the schematics... ::) In these filters, the frequency is adjusted clockwise. ¿correct?, so for the LPF the lowest frequency is when the potentiometer is fully anticlockwise so the B and C sections wipers go towards ground. The A section rotation is not signaled, but if it is wired as the other sections..., clockwise rotation is wired towards the R64 10R output resistor...¿right? ???
Correct.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

abbey road d enfer

Re: SSL 242 filters question
« Reply #8 on: January 11, 2021, 05:09:49 PM »
well, you would want to bring your HPF from "nothing" and up to whatever the max rage is for.  The LPF you would want the opposite.  Start at the max and turn down to the minimum.
That is not the way it's usually done. Both the LPF and HPF increase frequency CW.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

john12ax7

Re: SSL 242 filters question
« Reply #9 on: January 11, 2021, 06:10:51 PM »
That is not the way it's usually done. Both the LPF and HPF increase frequency CW.

That is preferred imo.  But the ssl doesn't work like that.  CW increases frequency for HPF,  but decreases it for LPF.


JAY X

Re: SSL 242 filters question
« Reply #10 on: January 13, 2021, 02:35:47 AM »
Hi!,

Yesterday I found a 4000 service manual pdf. In the SL611G, the filters in the front panel are labelled as following, from left to right:

LPF: OUT, 25, 75, 125, 200, 300, 350  HZ

HPF: OUT, 12, 8, 5, 4, 3.5, 3 KHZ

So, it seem that both filters are adjusted clockwise, but the HPF is numbered decreasingly.

Jay x


 

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