5235 card

[laszlo]

Dear forum

Long time no see.
Is there anyone who has tried to make 120hZ 18dB card for 5235?
I can produce the print but need the component list.

br Laszlo

[laszlo]

Great Thanks!!!


120Hz is not normal value.
You have to figure out the values yourself.

From 5235 manual;

79392

[Lee in Montreal]

I think I have them but for 80Hz. Maybe I an wrong. :confused:

[Odd]

Hjalmar you are right.

When I read the manual again I see you are right.
We should delete posts above for not having incorrect info about this.


You will find a lot of info about 5235 here in French;
http://vintage-jbl.forumpro.fr/t3066-filtre-actif-jbl-urei-5235

[dn92]

I'm the author of this French thread (I still have plans to translate it here) and I can help. You can use any JBL 18dB to do your own 18dB 120Hz.
Somewhere in the thread there is the formula for calculating component values for a 18dB Butterworth filter with a single opamp.

You can also use JBL values for another frequency and simply recalcule them as a ratio of the frequencies, but as JBL used normalised values for'the components and you'll get non exact values.

[4435]

R1 = 9.1k
R2 = 91k
R3 = 27k
R4 = 5.6k
R5 = 18k
R6 = 91k

C1 = 0.15uF
C2 = 0.068uF
C3 = 0.01uF
C4 = 0.22uF
C5 = 0.033uF
C6 = 0.033uF

[dn92]

R1 = 9.1k
R2 = 91k
R3 = 27k
R4 = 5.6k
R5 = 18k
R6 = 91k

C1 = 0.15uF
C2 = 0.068uF
C3 = 0.01uF
C4 = 0.22uF
C5 = 0.033uF
C6 = 0.033uF


R1 = 4.75k
R2 = 4.75k
R3 = 4.75k
C1 = 0.33uF
C2 = 1uF
C3 = 0.056uF

R4 = 9.53k
R5 = 3.74k
R6 = 64.9k
C4 = 0.1uF
C5 = 0.1uF
C6 = 0.1uF

Many other combinations can be calculated, the easiest is by choosing identical values for R in the case of LF filter and C for HF filter. The advantage of using three identical values is interesting as when buying components to an on-line shop, you'll get large quantities that can be then used. Drawback is that to get more precise response, taking into acount that values are limited within a serie (E24..), you can optimise each cell, but the calculation is a bit more complicated (use D. Shelf book for this).

For Butterworth 18dB/oct

LF:
C=1/2.pi.f.R
C1/C=1.392646782
C2/C=3.546818277
C3/C=0.202451073
HF:
R=1/2.pi.f.C
R/R4=1.392646782
R/R5=3.546818277
R/R6=0.202451073

With these formulas you can also detect what are the errors or not so precise values in JBL tables.