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Old 8th May 2014, 01:34 PM   #1
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Question Looking for alternative to a stepped attenuator and identifying a switch

It's time that I build a passive preamp for my office. I found this website online the other day and really like how easy of a build it was. The only problem is that the DACT CT2 - Stepped Attenuator is way out of budget for me. How would I go about finding a suitable alternative? What should I look for?

Also can anyone identify the switches used? I've included images on this thread from the link.

Thanks for the help,
Alfa

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Old 8th May 2014, 01:44 PM   #2
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Not sure about the switch, But I bought one of these Dact Type SMD Stepped Attenuator 21 Step Free Ship | eBay a few years back (not sure if it was the same seller or not) and I'm very happy with it.

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Old 8th May 2014, 02:12 PM   #3
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Quote:
Originally Posted by wintermute View Post
Not sure about the switch, But I bought one of these Dact Type SMD Stepped Attenuator 21 Step Free Ship | eBay a few years back (not sure if it was the same seller or not) and I'm very happy with it.

Tony.
Wow thanks for the quick response. I'll need 2 right? One for each channel?

I also noticed a $39 "Balance XLR DACT Type 21 Stepped Attenuator Potentiometer 20K" where it looks like one stacked behind the first.
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It looks like I need to do more research. I also found a "4Pole 24 Step Attenuator Volume Control Pot Log 500K A Stereo Potentiometer" for $22 on eBay.
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Old 8th May 2014, 02:22 PM   #4
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Check out kikitronic on ebay.com, same attenuator but using Dale resistors. I would post a link, but eBay links never work on this forum
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Old 8th May 2014, 02:22 PM   #5
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I was able to find the switches here:
Audio Solutions

I'll update this post when I find a store that sells them
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Old 8th May 2014, 02:23 PM   #6
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Elmas are lovely, i have a vintage stepped attenuator in my amp but they are ~$200 vs $40 for the eBay ones. Both do the same job at the end of the day.

http://www.goldpt.com/
http://www.dact.com/

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Old 8th May 2014, 02:32 PM   #7
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Okay so a lot of places sell Elma switches. I haven't had much luck finding information out about what pole vs position mean when referring to switches. Anyone have a quick explanation on the two?

Also I'll want to go with non-Shorting rotary switches right?
Quote:
Shorting = Make before break…means the contact makes connection with the next pole before breaking the last connection

Non-shorting = Break before make…means the switch breaks the connection with the current pole, before connecting to the next.
Thanks for help everyone!
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Old 8th May 2014, 02:35 PM   #8
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Make before break for use as a volume attenuator.

Break before make for use as an input/output selector.

No idea about pole vs position, not familiar with those terms.
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Old 8th May 2014, 02:37 PM   #9
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Quote:
Originally Posted by mcandmar View Post
Make before break for use as a volume attenuator.

Break before make for use as an input/output selector.

No idea about pole vs position, not familiar with those terms.
Ohh that makes more sense. Thanks for those links. Looking at them now. I don't want to spend $60+ on Elma switches for my first project. I might consider it down the line but for now I'll look at a few alternatives .

Also I found this on your first link:
Click the image to open in full size.

Makes a bit more sense about pole vs positions
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Old 8th May 2014, 02:45 PM   #10
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24-position, 4 pole MBB for the ladder type attenuator. Needs two resistors per channel, per position.

24-position, 2-pole MBB for series type. Needs one resistor per channel, per position and one common resistor.

4-position, 2-pole MBB for input selection. I use 4-pole switches for this and use the third and fourth pole to switch grounds and short the unused inputs, this helps with crosstalk between inputs. Because the switch is MBB, this shorts out the input and completely suppresses the pop associated with switching inputs when there is active signal on more than one.
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