SSL 242 filters question

[JAY X]

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]

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.

 

[JAY X]

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]

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]

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.

 

[JAY X]

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]

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.

 

[abbey road d enfer]

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.

 

[abbey road d enfer]

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.

 

[john12ax7]

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]

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

 

[JAY X]

Hi!

¿Could someone check my schematic and layout drawing? This is the schematic and layout for the 18db triple gang LPF. I want to make sure it is correct...before i get a headache...

Thank you very much!!

Jay x

 

[L´Andratté]

Wipers unconnected on C & B?
The schematic doesn´t say rev.log. it says log. (maybe that´s why the pots are not wired all the
same)?
The best "feel" for this SallenKey filters would be 3xrev.log. (like you propose), don´t know what´s the catch here...

 

[abbey road d enfer]

Wipers unconnected on C & B?
The schematic doesn´t say rev.log. it says log. (maybe that´s why the pots are not wired all the
same)?
The best "feel" for this SallenKey filters would be 3xrev.log. (like you propose), don´t know what´s the catch here...

Maybe the OP edited the schemo, but it says RevLog.
It seems to be correct, although a more complete schemo/layout would clear any doubt.

 

[L´Andratté]

I was talking about the official SSL schematic at the top of the thread, it says "A/log Triple switch", maybe that means antilog.
Those should be wired all in the same direction re. cw/ccw but they aren´t?

 

[JAY X]

Hi!

The original schematic says 47k A/log. Antilog.

 

[abbey road d enfer]

I was talking about the official SSL schematic at the top of the thread, it says "A/log Triple switch", maybe that means antilog.
Those should be wired all in the same direction re. cw/ccw but they aren´t?

The layout on the 4000 was such that the HPF was CW and the LPF CCW. The logic was that the more you turn, the more pronounced the effect, and also it was consistent with the EOT switches.

 

[JAY X]

Hi!

Attached is a sketch of the switching of the filters. Both HPF and LPF, can be switched in and out independently. But i want to make shure my drawing is right about the NC and NO switch contacts.

Jay x

 

[JAY X]

After the schematics, i understand that, for both filters to be bypassed, the bypass switch contacts must be NC, normally closed.

 

[abbey road d enfer]

After the schematics, i understand that, for both filters to be bypassed, the bypass switch contacts must be NC, normally closed.

That's correct.