Need a cheap way to attenuate a signal?

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Benjamin AM
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Need a cheap way to attenuate a signal?

Post by Benjamin AM » Mon Mar 22, 2010 6:28 pm

If you're handy with a soldering iron, you can do it with a pot(50k Lin is good). If not, this passive mixer works very well. I find that it compliments the CP-251 very well. http://www.sweetwater.com/store/detail/SplitMix4/. edit-note that the pots are audio tapered.
Last edited by Benjamin AM on Tue Mar 23, 2010 10:56 am, edited 1 time in total.
Little Phatty Stage II, Rogue, Cp-251, Soldering Iron

dave500
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Post by dave500 » Mon Mar 22, 2010 7:10 pm

Benjamin,
How do you like your CP-251?
Model D, Little Phatty Tribute w/cv, The Rogue, MF-102, CP-251, Animoog and Filtatron

ColorForm2113
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Post by ColorForm2113 » Mon Mar 22, 2010 11:32 pm

Does that little art mixer work well with cv?
My modular so far: Q104, Q106 x2, Q107, Q108, Q109 x2 , Q116, Q118, Q127 w/Q140, Q130, STG Wave Folder, Mixer and Mankato playing with Moog Voyager, VX-351, CP-251, MF-104M x2 ( STEREO!) Volca Beats and Bass, Arturia Beat step

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varice
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Post by varice » Tue Mar 23, 2010 4:56 am

Hey, thanks for suggesting the SPLITMix4. I think it could also be used as an alternative control input for Nord Modular synths:

http://electro-music.com/forum/viewtopic.php?t=32424

The specs don't mention it, but I assume that the SPLITMix4 has audio taper pots. Can you tell if they are audio or linear taper?
varice

Benjamin AM
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In retrospect

Post by Benjamin AM » Tue Mar 23, 2010 10:45 am

I don't know how I overlooked the fact that the pots are Audio(Log) tapered. Now that you mention this, I do notice that the signal is heavy on the end. I opened it up to see how easy it would be to replace the pots with linear tapers. To my disappointment I found that they are the dual ganged(stereo) panel mount type (100k-A). Anyhow, I am going to replace them with dual ganged 50k linear pots that I found at Small Bear(http://www.smallbearelec.com/Detail.bok?no=736). Unfortunately they are not panel mount but they'll work. I'll let you know how it turns out.
Little Phatty Stage II, Rogue, Cp-251, Soldering Iron

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varice
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Post by varice » Tue Mar 23, 2010 3:07 pm

Audio taper pots are not all bad though. They can give you more control range of small amounts of modulation, such as when you want to add just a little LFO vibrato CV to the pitch of a VCO or the cutoff of a VCF...

Thanks again for the suggestion. I've been looking out for a low cost CV attenuator box. It seems that there are not many available.
varice

Just Me
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Post by Just Me » Tue Mar 23, 2010 3:52 pm

I've got the DOD resistance mixer 240. 4X1 mono device. There is no board it is all discrete devices. Very easy to add more 1/4" jacks or change some of the pots from A to L.

Link: http://www.dod.com/accessories/accessories.htm
"Music expresses that which can not be said and on which it is impossible to be silent."

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varice
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Post by varice » Tue Mar 23, 2010 4:45 pm

Wow, that DOD 240 looks pretty good. I like the knobs on the top and separated a bit more than the ART SPLITMix4. Thanks for posting!
varice

Just Me
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Post by Just Me » Tue Mar 23, 2010 8:09 pm

Here is a pic of the innards of my DOD.
As you can see, it is customizable.
Image
"Music expresses that which can not be said and on which it is impossible to be silent."

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varice
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Post by varice » Tue Mar 23, 2010 9:24 pm

Thanks much for the pic... It confirms for me that the box wiring is optimized as a 4 input to 1 output mixer. To optimize it for use as a 1 input to 4 output splitter function, it would need a little wiring modification.

A bit hard for me to tell from the pic and/or my laptop display - are the resistor color bands yellow-purple-RED-gold or yellow-purple-ORANGE-gold?
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Just Me
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Post by Just Me » Wed Mar 24, 2010 8:08 pm

They are 47K ohm. (Orange)
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tubeampguy
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Post by tubeampguy » Wed Mar 24, 2010 10:37 pm

This is what Bob Moog made for modulars.
Image

Benjamin AM
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Post by Benjamin AM » Fri Mar 26, 2010 3:09 pm

Hey Tubeampguy, thanks you so much for posting the pic. I made one of these with a 100k and it works awesome. One thing that I could not gather from the picture was where lug one was connected to.. I assumed to the housing, but when I soldered it this way there was no attenuation so I had to jump it over to the ground. Do you own any of these to check lug 1?
Little Phatty Stage II, Rogue, Cp-251, Soldering Iron

tubeampguy
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Post by tubeampguy » Sat Mar 27, 2010 5:16 am

Benjamin AM wrote:Hey Tubeampguy, thanks you so much for posting the pic. I made one of these with a 100k and it works awesome. One thing that I could not gather from the picture was where lug one was connected to.. I assumed to the housing, but when I soldered it this way there was no attenuation so I had to jump it over to the ground. Do you own any of these to check lug 1?

No I don't own these(sorry) I found this picture years ago (v.90 dial up modem) online.

The body of the pot might be isolated? Did you check it with a meter to see if there's continuity? Sometimes just the threaded area is the ground path.When its tightened down onto metal (like a control plate) It completes the circuit. You are right about pin 1 being ground. Signal comes in on 3, goes out 2(wiper) 1 is ground. 3 and 1 can be reversed to change CW to CCW.



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Benjamin AM
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Post by Benjamin AM » Sat Mar 27, 2010 4:49 pm

Looking closely at the picture I believe that I see a wire soldered to the threading. I would take a bet that the original pots were 50k linears, that's what's used on the CP-251.
Little Phatty Stage II, Rogue, Cp-251, Soldering Iron

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