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Re: Duh... Q: EDP & CV pedal for feedback control

Duh...What's the difference between "Volume" and "Expression" pedals? I
always thought that they were the same. How can I tell which one I have?

At 12:04 AM 11/25/98 -0800, you wrote:
>At 8:04 PM -0800 11/24/98, Sean T Barrett wrote:
>>>Only down side is the log taper on volume pedals...
>>>linear seems a bit easier to use for feedback control.
>>Couldn't the software reinterpret this--apply a curve
>>to the input numbers to (approximately) linearize it?
>yeah, that would be easy enough. Of course, then you have the opposite
>problem with anyone using linear taper pots. So then you end up adding yet
>another parameter to allow a choice, and then a lot of time explaining 
>this obscure log/linear parameter does....:-)   well, there would be one
>problem with this, in that the analog level runs through an a/d convertor
>with a fairly limited range. you'd probably end up with some weird
>resolution problems in some parts of the pedal range.
>anyway, for John, here's how to set the trimpot:
>This requires that you actually open up the unit, and have it opened with
>the power on. *Please follow appropriate electrical safety rules!!*  If 
>are not careful and you fry yourself, please don't blame me!
>There's a trimpot on the PCB, near the left side, by the volume knobs. 
>job is to trim a dc offset from a VCA. Sounds like your's is not set right
>for some reason, which would cause the thump you hear.
>To set it you need to run one of the built in diagnostic tests. The test
>basically turns the VCA on and off at about 60Hz, so if there is an offset
>you can hear the resulting tone in an amplifier. (or see it on a scope,
>whichever way you like.)  While that's going, you adjust the trimmer until
>the tone/waveform reaches it's mimimum.
>To get into the trimmer test, Start the unit while holding the Parameter
>and Record buttons down. Keep them held while the startup screen goes by,
>until the display shows all t's. Then let go. Should say 7F. Press
>parameter so the "Keys" LED is lit, then press Insert to start the trimmer
>You should hear a ~60Hz tone in an amp. (turning input volume off, mix to
>"loop", and the output volume up helps.) The tone will change in level as
>you adjust the trimpot. Adjust to where the tone is at it's lowest level.
>(you'll still hear hashy noise sounds, but the 60Hz should become nearly
>inaudible.)   After you set the trimmer, pressing parameter again will 
>the test. Then you can turn the echoplex off and power back up normally.
>Kim Flint                   | Looper's Delight
>kflint@annihilist.com       | http://www.annihilist.com/loop/loop.html
>http://www.annihilist.com/  | Loopers-Delight-request@annihilist.com
Howard Harawitz      howard@brooknorth.com              
Brooklyn North Software Works Inc.
Halifax, Nova Scotia, Canada 
Telephone: 1-902-423-0257
Check the Halifax Harbor Cam: http://www.brooknorth.com/camsite/