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Old 8th March 2011, 06:19 PM   #1
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Bob Richards's Avatar
Join Date: Feb 2011
Location: Portland Oregon, USA
Default Warning about TKD LOG pots

TKD LOG pots are probably pretty good when used as a volume control, where both the input and the output have a common connection (ground). I found out the hard way that they are not usable in a James or Baxandall style tone control circuit. This is because the main resistive element has three taps, each of which have separate resistors that all meet up at the end of the main resistive element that must be common to input and output. If you measure from the wiper to one end while rotating the shaft, the value goes approx 25% higher than the stated value of the pot, at some point during the rotation. From wiper to the other end this does not happen. The Noble AP-25 (discontinued) does not have this problem. It's about how they turn a linear taper into a LOG taper. Apparently a new way of doing that. I ordered and recieved 5 of these TKD pots from Parts Connexion in Ontario. Their return policy is such that I'm probably out $180 ($35 each plus shipping), or at least $50 (shipping both ways and a 15% restocking fee). How FUN...
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Old 9th March 2011, 01:22 PM   #2
DF96 is offline DF96  England
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Join Date: May 2007
So they have incorporated into the unit the old dodge of resistive loading a linear pot to get a pseudo-log law? I think you should stamp your feet and make a big noise, unless the small print insists that you have read the datasheet before ordering anything.

Are these genuine, or cheap fakes? Or are 'reputable' manufacturers now faking their own products?
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Old 9th March 2011, 07:08 PM   #3
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Join Date: Feb 2011
Location: Portland Oregon, USA
The spec sheet was in Japanese, but did show a schematic of the pot down at the bottom, which showed the three taps and additional resistors. Partsconnexion in Ontario is going to wave the restocking fee (15%), but will only give me store credit for the $180. Them and Percy don't seem to give a dam about customer satisfaction. This used to be a very fun hobby, that I've been doing since the early 1960's. I probably won't do many more projects after this one. Part costs and being able to actually get the parts is getting more frustrating than it's worth to me.
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