API 5003 - Knobs found! Calibration / Zero Measurement?

outoftune

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Found the knobs. Thanks!

Final thing I'm wondering now is if anyone knows if there is a measurement for when the pots are at 0?

Can I just match it up with the faceplate legend?

I wanna make sure they are even because I'd like to try these on masterbus. Anyone else using them in this application? Am considering changing one of the LF selections to 60hz.
 

dmp

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I ordered sifam collet knobs from Selco that looks nice. If you used the Omeg pots they might be 4mm shaft. With a pointer and a cap, the knobs are about $3.50 each. The pointer allows for nice adjustment.
 

kazper

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http://classicapi.com/catalog/product_info.php?cPath=23_40&products_id=34

I used the 5/8" plain with the silver inserts.
 

outoftune

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Final thing I'm wondering now is if anyone knows if there is a measurement for when the pots are at 0?

Can I just match it up with the faceplate legend?

I wanna make sure they are even because I'd like to try these on masterbus. Anyone else using them in this application? Am considering changing one of the LF selections to 60hz.
 

desol

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Knobs really aren't the problem...it's the pots that are hard to find... :-\
 

dmp

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I used RMAA to find the knob position for flat response, then attached the knobs with the pointer at the zero.
 

Denyle Guitars

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I used 41 detent pots so if they don't suck too bad, it should be close at the noon position. I haven't done any measuring. They sound good and I might just leave it at that.
 

desol

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Out of tune, so the pots you received from TAW have a centre detent and 4mm shaft correct?
 

dmp

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I used Omeg center detent pots for a different EQ project (169s) and when I measured them with RMAA they weren't even close to flat, +/- 1or2 dB. and the two channels didn't match at all. With a good knob with a pointer, I can match two channels and use on a bus. Probably not using center detent pots on anything again.
 

desol

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What was the resistance tolerance for the Omeg's you used? +/- 20%? Maybe that has something to do with it?
It looks like 10% tolerance parts are available..

http://www.alphastat.de/bilder/omeg/Omeg-E16-(ECO)-potentiometer-data.html

It would be good to get pots that when at centre are indeed flat(ter) on the eq curve. I'm just compiling an order...so i'm in the learning phase with this...but i do want to order them correctly the first time.
 

dmp

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The ECO Pots are really nice - I've used them on several projects and love them.  But no center detent. Hence, the knob and pointer to identify center position, which is what I recommended.
The carbon pots from AML are what I was talking about. I don't know their tolerance but I'm sure that is key.
http://www.audiomaintenance.com/acatalog/potentiometers_carbon_16mm_diameter_dual_gang.html
I would think a 10% tolerance (if the center detent could be +/-10% from mid pot resistance) would cause a significant difference from flat freq response.
 

desol

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dmp said:
The ECO Pots are really nice - I've used them on several projects and love them.  But no center detent. Hence, the knob and pointer to identify center position, which is what I recommended.
The carbon pots from AML are what I was talking about. I don't know their tolerance but I'm sure that is key.
http://www.audiomaintenance.com/acatalog/potentiometers_carbon_16mm_diameter_dual_gang.html
I would think a 10% tolerance (if the center detent could be +/-10% from mid pot resistance) would cause a significant difference from flat freq response.

The small order that i'm putting together is for ECO pots w/centre detent(if available) @ 10% tolerance. Standard ECO pots are 20% tolerance. 10% is the best you can get in ECO (i think). If i could get a 5% part w/detent that would be even better.
Has anyone else used detent pots and then measured them for their response, at centre? I prefer to have centre detent, but they have to be flat AT that point.
 

mitsos

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DMP, I like your pointer knob method!  I am not familiar with the 169 schematic, but if you removed the detent pots and still have them, I'd be interested to know what R their "center" is at, and what their max R is. If it's not too much trouble, that is. cheers!
 

dmp

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I didn't ever remove them as they are not very common types. I posted some rmaa plots in the 169 thread, but I don't know the resistances.
 
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