Author Topic: DIY stepped attenuators  (Read 1400 times)

audiovisceral

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  • Posts: 150
DIY stepped attenuators
« on: January 04, 2010, 03:11:59 AM »
I'm interested in building a bunch of DIY stepped attenuators. First, I am wondering if anyone knows if there is a Mouser or Digikey part number for raw rotaries like this:

http://cgi.ebay.com/1-PC-Selector-Switch-24-step-2-pole-Attenuator-Pot-New_W0QQitemZ270500359836QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item3efb13ee9c

I'd prefer not to have to rely on eBay to find what I want.

Second, if you are using a calculator like this:
http://www.quadesl.com/attenuator.html

Is the desired attenuation in dB always 60 dB? How do you know what it should be, in a case where you are simply ugrading for example a generic 220k audio pot in a random piece of gear?

Thanks.
« Last Edit: January 04, 2010, 04:10:40 AM by audiovisceral »


RuudNL

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  • Leerbroek / The Netherlands
    • Microphone modding
Re: DIY stepped attenuators
« Reply #1 on: January 04, 2010, 03:26:19 AM »
I have used these switsches before, but the ones I used were pretty crappy!
The switches did not 'track' properly; when you turned the shaft one step, one section switched but the other section switched somewhere in the middle or stayed between two positions.
The only solution was to take the switches apart and glue the rotor plates to the shaft!
(By the way: it is easy to reduce the number of steps by drilling a small hole and inserting a short pin or a piece of a paperclip!)
« Last Edit: January 05, 2010, 12:33:23 AM by RuudNL »
There is a solution for every problem!

audiovisceral

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  • Posts: 150
Re: DIY stepped attenuators
« Reply #2 on: January 04, 2010, 04:06:06 AM »
If that is the case, is there any source for higher quality raw switches? There is no way I'm paying hundreds of dollars for Goldpoint when I can DIY my own.

TheGuitarist

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  • Posts: 498
  • Australia
Re: DIY stepped attenuators
« Reply #3 on: January 04, 2010, 04:11:05 AM »
http://diypartssupply.com/index.php?main_page=product_info&cPath=5&products_id=13


http://diypartssupply.com/index.php?main_page=product_info&cPath=5&products_id=11


 ;D


Oh and i'm pretty sure those are the switches goldpoint use in their custom switches that they solder your resistors onto or however they word it.
« Last Edit: January 04, 2010, 07:30:54 AM by TheGuitarist »

haima

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  • Posts: 810
  • Melbourne, Australia
Re: DIY stepped attenuators
« Reply #4 on: January 04, 2010, 05:39:55 AM »
those elmas are VERY nice... highly recommended if you can stretch the budget there.

not sure about cheaper options, greyhill make some good ones with less switch positions... might be worth a look.
« Last Edit: January 04, 2010, 09:56:24 AM by haima »

Silvas

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  • Posts: 678
  • Bogota, Colombia
    • http://www.myspace.com/audioeng80
Re: DIY stepped attenuators
« Reply #5 on: January 04, 2010, 09:48:58 AM »
These are the uraltone switches from chinese seller Andrew. I have these in my DLA2A, have a look:  http://www.groupdiy.com/index.php?topic=36889.0 , they work great, just doent´t feel like an elma, and the switch stop is a bit fragile (but is easy to open the switch and modify the # of positions). 10 usd apiece shipping included, iirc.


I have used these switsches before, but the ones I used were pretty crappy!
The switches did not 'track' properly; when you turned the shaft one step, one section switched but the other section switched somewhere in the middle or stayed between two positions.
The only solution was to take the switches apart and glue the rotor plates to the shaft!
(By the way: it is easy to reduce the number of steps by drilling a small hole and inserting a short pin or a pice of a paperclip!)

RuudNL, so far so good no problems with my switches, but i expect QC to be inexistent at that prices !


 

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