Reverse log potentiometers [again...] - Page 1
Forum section: electronics / repair

author: EugenioN
author_rank: Contributor
timestamp: June 30, 2025, 08:10:17 pm
content: Hi all.My pile of broken Behringer and Mackie mixers is growing fast in the last few months: they are coming to the end of their life because of wear, I can relate to that.Faders are usually cheap and easy to source on Aliexpress, but reverse log potentiometersdefinitely are the rarest among the rare.They look similar to Alps RK09 series, but with a fancy 5KZY taper curve. Somehow this should be a reverse log because of the differential amplifier used in mic inputs, but I can't gather any info.I'd really love to buy a decent quantity of these unicorns to spread the shipping costs, but I can't figure out where to source them. Aliexpress as some of them listed with a price tag way too high (2.5euro each plus shipping), considering they clearly are chinese rip-offs of the genuine alps/matsushita parts.Suggestions?

author: themadhippy
author_rank: Super Contributor
timestamp: June 30, 2025, 08:48:58 pm
content: Quote2.5 euro expensive for a fader

author: EugenioN
author_rank: Contributor
timestamp: June 30, 2025, 09:54:36 pm
content: Quote from: themadhippy on June 30, 2025, 08:48:58 pmQuite a lot indeed. Those Behringer/Mackie mixers (8/12 channels, analog) could be worth no more than 50euro each when working fairly fine.2.5e each gain trim, plus shipping, plus labour cost easily exceeds the bulk value of the machine itself.Ok, if no other contribution will come out, I'll suggest my customers to toss those things in the bin

author: Haenk
author_rank: Super Contributor
timestamp: July 01, 2025, 05:02:59 am
content: Quote from: EugenioN on June 30, 2025, 09:54:36 pmThese are built to a low price, so there is not a huge margin beyond the cost of components - however they purchase millions and millions of the required components at once. So replacing a larger number of components purchased on the market is just more expensive than the worth of the used mixer, likely even more expensive than a new one. Not even counting in the labour.And lets face it: faders are just "consumables", and don't expect too much lifetime either, when the whole mixer costs less than one replacement fader of a professional mixer...

author: Audiorepair
author_rank: Frequent Contributor
timestamp: July 01, 2025, 07:17:41 am
content: A few years ago I investigated having a batch of Unobtainium faders made for an old but popular Roland vintage drum machine.I found several Chinese companies on Ali Baba who could make a batch to your own specifications.I almost went for it - I was looking at a ballpark of around £500 for thousands of these things, can't remember now the exact pricing.I figured I could have as many as I wanted, and then sell what I could at an acceptable price on Ebay, to hopefully cover all my costs in a year or so.If you think the market for these reverse log pots is big enough, then maybe you could investigate doing the same.Otherwise you may just realise why these things simply are not available.

author: JohanH
author_rank: Frequent Contributor
timestamp: July 01, 2025, 07:42:54 am
content: You could use a larger value linear potentiometer and add a resistor in parallel. It's possible to approximate a reverse audio potentiometer this way, both when the potentiometer is wired as a voltage divider and as a series variable resistor. The more common audio potentiometer taper curve can only be approximated when the potentiometer is wired as a voltage divider.https://www.tubesandmore.com/tech-articles/potentiometer-taper-modificationshttps://www.tubesandmore.com/tech-articles/potentiometer-taper-modifications-interactive