How to connect a gain pot or switch to the ssl9k

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jeroddumas

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Jun 19, 2004
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Location
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I know this is a dumb question, how would you connect a gain pot or gain switch to the ssl9k pcb? and where can I source the pot in the US.
 
> I know this is a dumb question

How do you know it is a dumb question? Nobody is born knowing where to put gain-parts on every board ever made. Seems like a pretty smart question to me.

> how would you connect a gain pot or gain switch to the ssl9k pcb?

Assuming you use this layout:
http://www.boemboemklap.nl/ssl9000/

Then there are two gain-set resistors (switches or pots) and they connect where I put red dots:
SSL9K-Gain.gif


> and where can I source the pot in the US.

Ah, that's a good question with a dumb answer. You can't get that pot. (I sure hope someone jumps in and corrects me). In an emergency, you can buy a dual 5K audio-taper pot from DigiKey for $3, if they have it in stock (they often don't), and turn the knob backwards (anti-clockwise to increase gain). A switch sounds like a better plan, except you need a 2-pole switch, and the most common types of switches only give 6 positions with 2 poles. The SSL9K gives a maximum gain of about 72dB, minimum gain of about 12dB, a 60dB range. With 6 positions and equal steps it works out 12 24 36 48 60 72dB. 12dB steps are livable, but pretty big.
 
Thanks!! That's the layout I am using. This is my first mic preamp project, and I appreciate any help. Should I use the dual pot, or can I put in two pots and have a gain and volume control?
 
jerrodumas. No you can't use two seperate pots like that (though it would 'work' with some interesting sonic effects I'm sure).The circuit functions a little differently, spreading the gain over more opamps. Keith posted an explanation somewhere (or was that in the Dallas-style dream sequence of RO......).
 
Another question,

What's the purpose of Ra and Rb in the schematic? Was that to compensate for the tolerance of the two sections of the pot?

Thanks!

Michael
 
PRR said:
> I know this is a dumb question

How do you know it is a dumb question? Nobody is born knowing where to put gain-parts on every board ever made. Seems like a pretty smart question to me.

> how would you connect a gain pot or gain switch to the ssl9k pcb?

Assuming you use this layout:
http://www.boemboemklap.nl/ssl9000/

Then there are two gain-set resistors (switches or pots) and they connect where I put red dots:
SSL9K-Gain.gif


> and where can I source the pot in the US.

Ah, that's a good question with a dumb answer. You can't get that pot. (I sure hope someone jumps in and corrects me). In an emergency, you can buy a dual 5K audio-taper pot from DigiKey for $3, if they have it in stock (they often don't), and turn the knob backwards (anti-clockwise to increase gain). A switch sounds like a better plan, except you need a 2-pole switch, and the most common types of switches only give 6 positions with 2 poles. The SSL9K gives a maximum gain of about 72dB, minimum gain of about 12dB, a 60dB range. With 6 positions and equal steps it works out 12 24 36 48 60 72dB. 12dB steps are livable, but pretty big.

Can someone explain How should I connect the Pot to the PCB.
I have a dual 2k2 Pot.

I imagine tgis is like 2 pots , each with 3 pins.

In the Board theres 2 holes for Gain A and 2 holes for gain B.
I imagine one pot connects to Gain A spots, and the other part of the pot to gain B.
So wich legs go to each hole?

thanks,
and sorry for the dumb and basic question
 
bit of a bump.

are there any reverse 5k (or the correct gain pots for that matter) floating around now? Anything wrong with using a 5k pot?

Is everyone just using gain switches? I'd prefer a potentiometer if i can do it.
 
Most people are using the 2K2 rev log pots from Audiomaintenance.com .  I think 5K would mean you'd have silence from 5K to 2K5 resistance (2K5 is what is originally spec'd). For a revlog pot that may mean that for the first quarter turn the pre would be silent, then you'd have 75% of the turn radius to do 100% of your gain. Would "work" but the gain would be a bit more touchy.

BTW 2K2 pots will give you a bit higher minimum gain, IIRC 6dB, which is no problem, then you have 100% of the turn radius to dial the rest of the gain.
 

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