3D "AIR" EQ - "Night EQ" PCB's Complete!

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Example:
If you have 50k for R38, you need to change R39 to 562R -- and this for all filter stems.

Also you need to scale down R30 by factor 10 and then scale up C13 for same filter response. Calculate it.

Finally, I made R48 a trimmer to address difference in volume when switching from bypass. You might not need this. Can do any time later.
 
Again you confuse me 😄

First you say I should not bother with 50K, and then you point me to 50K dual gang potentiometers and the resistors to be replaced. The resistor values I asked for and your answer is appreciated, thanks.

My concern with the dual gang potentiometers is that they have a tolerance of 20%, and I am unsure about the matching of the two gangs. I can't find that in the datasheet either. I know the dual gang pots are a really cost-effective solution, but I'm not looking for the cheapest option per sé. I kind of like the stepped switch idea and the precision it brings.

Let me assume that you indeed mean that the conversion to 50K potentiometers (or switches) is not necessary and that a stepped switch with a value of 500K is fine. If I proceed to enter these values into Harpo's excel I get the following data:

corresponding part
R feedbackR30
56200​
ohms (if you change it, also change R48 for bypass to the same value)
max.boostR37,39,41,43,45
5​
dB
max.cutRV36,38,40,42,44
-5​
dB
step positions
21​
(2 to 25 positions)
max.cut between switching
-6​
dB (must not be higher than regular max.cut)
R in parallel
112134​
ohmsclosest E96 value
113000​
StepBoost/Cut
value in dB
this is
voltage gain
required R in
(to substitute Rseries+RV)
with 'R in parallel'
the R at the switch is
closest E96 value
in ohms
1​
-5,000​
0,5623​
99939​
864643​
866.000
2​
-4,500​
0,5957​
94349​
571628​
576.000
3​
-4,000​
0,6310​
89071​
420620​
422.000
4​
-3,500​
0,6683​
84088​
328651​
332.000
5​
-3,000​
0,7079​
79385​
266860​
267.000
6​
-2,500​
0,7499​
74944​
222532​
221.000
7​
-2,000​
0,7943​
70752​
189239​
191.000
8​
-1,500​
0,8414​
66794​
163349​
162.000
9​
-1,000​
0,8913​
63057​
142671​
143.000
10​
-0,500​
0,9441​
59530​
125807​
127.000
11​
0,000​
1,0000​
56200​
111806​
113.000
12​
0,500​
1,0593​
53056​
100015​
100.000
13​
1,000​
1,1220​
50088​
89966​
90.900
14​
1,500​
1,1885​
47286​
81312​
80.600
15​
2,000​
1,2589​
44641​
73793​
73.200
16​
2,500​
1,3335​
42144​
67211​
66.500
17​
3,000​
1,4125​
39787​
61409​
61.900
18​
3,500​
1,4962​
37561​
56263​
56.200
19​
4,000​
1,5849​
35460​
51676​
51.100
20​
4,500​
1,6788​
33476​
47568​
47.500
21​
5,000​
1,7783​
31604​
43875​
44.200

I'm not sure what the "max cut between switching" means. Does it perhaps mean the behaviour when using a break-before-make" switch? Is it important?

I think the rightmost column holds the resistor values that need to go between the switch steps. The "max cut between switching" influences the values in this column, so I would like to confirm I'm doing this right, before ordering bespoke stepped switches and potentially wasting a lot of money :).
 
Haven't looked at your math. Here's mine.

Those custom-made rotaries cost USD200 for 8 pieces. They are hand-made (so a reasonable price) and sure also worth supporting the seller.

Yet, for USD200 one could buy 250 pieces of dual taper pots for 0.8 a piece at Tayda and look for closest match from pins 1 to 3 across decks, and then in a second step from pin 1 to eyeballed mid position. Should be able to find 6 duals that match closely enough across decks. The remaining ones go to charity.

Anyway, once jam is pumping and crowd hopping , pot mismatch is a rather unlikely reason for complaints ;)

But agreed, my math doesn't compute cos those pots are out of stock at Tayda. Haven't checked whether they have 500k, nor what other have on offer.
 
You have a valid point about buying a surplus of those pots and matching them by hand; I did not think about that. I did check their site and they have the 500K version on stock in fact. Thank you for this perspective.

However, it feels a bit wasteful to buy 200+ potentiometers in order to find 6 useable specimens. I would like to make an effort in keeping the world sustainable, spending a bit more on a product and/or person to reduce the use of resources and/or generating waste is part of that. So the stepped switches have not left my mind yet, and if someone can confirm the values in the table in my prvious post (3D "AIR" EQ - "Night EQ" PCB's Complete!) that would be wonderful.
 
Hi all,
does anyone have PCB for PSU?
I found here this one but it doesnt looks like at finished projects.
 

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Hi all,
does anyone have PCB for PSU?
I found here this one but it doesnt looks like at finished projects.

That PSU was sold by PeterC at the time, but you will not find it at the present.
When I did my Night Eq I used the SSL9K PSU, that was a very popular project around here and there were plenty of those PCB's around.

At the moment you can buy a PCB psu from Silent Arts,
get the POSNEGPSU-rev02 and you will be sorted:

POSNEGPSU-rev02: EUR 6,50 each + shipping + VAT where applicable

https://groupdiy.com/threads/51xaudio-by-silent-arts.39570/
 
That PSU was sold by PeterC at the time, but you will not find it at the present.
When I did my Night Eq I used the SSL9K PSU, that was a very popular project around here and there were plenty of those PCB's around.

At the moment you can buy a PCB psu from Silent Arts,
get the POSNEGPSU-rev02 and you will be sorted:

POSNEGPSU-rev02: EUR 6,50 each + shipping + VAT where applicable

https://groupdiy.com/threads/51xaudio-by-silent-arts.39570/
Thank You Whoops, I will try to find SSL9K PSU and if I fail - then will order from Silent Arts :)
 
I do something like this. can be with attenuation pot, or jumper. Input INA134, and DRV134 output(...can be THAT...).
 

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I add new position 15kHz too. Simetrical input can be like early version on 5532, or THAT1240 for your choose. Two push switches, one for ByPass, second for SHelf on/off...i have few pcb, if someone intersted...
 
I add new position 15kHz too. Simetrical input can be like early version on 5532, or THAT1240 for your choose. Two push switches, one for ByPass, second for SHelf on/off...i have few pcb, if someone intersted...
My inbox doesnt work - i dont know why... please message me. Thank you
 
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