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Old 2nd February 2011, 03:07 PM   #1
djn is offline djn  United States
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Default Have you ever seen a 4 pin blue Alps pot??? need help

Hi all, A friend gave me a blue Alps pot the other day and I was looking at it this morning and noticed it has 4 pins per side. It is 100k and the model number is RH2702. What is the 4th pin for? How do I wire this thing?

Also, it is a click type, not smooth sweep.
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Old 2nd February 2011, 03:53 PM   #2
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probably a loudness tap...
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Old 2nd February 2011, 06:43 PM   #3
Doz is offline Doz  United Kingdom
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Yes, it's a loudness or "bass boost" tap... I have several of the damnedable things, and always manage to wire them up wrong ....
"To err is human.. to make a real balls-up requires a computer"
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Old 2nd February 2011, 06:54 PM   #4
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The loudness taps are on the outside if I'm not mistaken.
Are you sure it is a real Alps? I got one of those, it was a stepped attenuator in an Alps housing. But Alps never made those.
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Old 2nd February 2011, 07:45 PM   #5
taj is offline taj  Canada
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Found this in a Google search....

There's a new and strange fourth choice now. Apparently some company has built a stepped attenuator into a package similar to that of the ALPS Blue Velvet. It's marked as an ALPS pot, but the compnay claims not to know about this part (labeled RH2702) and the web site doesn't have any information on it. One guess is that it's made by a Chinese company called Soundwell. I've measured one, and it's got excellent channel matching. It's a bit tough to turn the knob, and there's a click in between settings unless you turn it quickly, but it fits the board and it's inexpensive. You can buy them for $6 each with a minimum order of 4 by contacting Wai Kei Leung of Wai Yip Electronics, Hong Kong. You should read the Head-Fi thread about these parts before buying.
Don't bother reading that Head-Fi thread, it's linked to the wrong topic (unless you like to read about people buying $6000 headphone amps. Man, I'm in the wrong business.)


Last edited by taj; 2nd February 2011 at 07:58 PM.
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Old 2nd February 2011, 08:34 PM   #6
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I have a few of these which I bought from a US dealer on ebay. Haven't wired one up yet, but I guess a multimeter would tell you which two contacts to join.
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Old 2nd February 2011, 09:39 PM   #7
djn is offline djn  United States
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Here is a pic of the guts. Yep, not made by ALPS but still looks good.

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