Hello All,
After having my B1 Korg for approx 3 years and loving the sound I decided to install a motorized volume remote control, it is not one of the complete kits from the store. I originally installed dual 50K DACT stepped potentiometers to allow for independent left/right volume and was very happy with the sound.
The new motorized pot is a dual 50K “Alps potentiometer” (log taper, and assuming it’s actually Alps brand ) which controls the volume just fine, but there is a noticeable attenuation of the upper treble that didn’t exist before.
Has anyone experienced this before when changing out potentiometers? I’ve read that builders have preferences for brands, and that certain components can have “a sound” but I honestly did not expect this drastic of a difference.
This is the item I purchased…
https://www.ebay.ca/itm/16493711073...var=464467343788&widget_ver=artemis&media=SMS
Any recommendations, suggestions, in-site would be great.
Thank You
After having my B1 Korg for approx 3 years and loving the sound I decided to install a motorized volume remote control, it is not one of the complete kits from the store. I originally installed dual 50K DACT stepped potentiometers to allow for independent left/right volume and was very happy with the sound.
The new motorized pot is a dual 50K “Alps potentiometer” (log taper, and assuming it’s actually Alps brand ) which controls the volume just fine, but there is a noticeable attenuation of the upper treble that didn’t exist before.
Has anyone experienced this before when changing out potentiometers? I’ve read that builders have preferences for brands, and that certain components can have “a sound” but I honestly did not expect this drastic of a difference.
This is the item I purchased…
https://www.ebay.ca/itm/16493711073...var=464467343788&widget_ver=artemis&media=SMS
Any recommendations, suggestions, in-site would be great.
Thank You
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^ Deleted a post related to roll-off with higher value pots b/c I didn't catch that they were both 50k. Read incorrectly that DACT was 10k. LOL!
So... tl;dr - No clue... but very interesting.
So... tl;dr - No clue... but very interesting.
it's simple as this - if you're sure (check with Ohmmeter) that pot is actually 50K (value not critical at all), no other reason than pot itself being utter drek
Hi Zen Mod,
the first thing I did when I received the motorized volume control was to check the resistance to verify that is 50 K. One channel measured 49.2 ohms and the other channel measured 49.5 ohms. So unless some magical burn in is required then it seems as you said… that the pot itself is drek.
I have a 50 K stereo pot that I purchased from parts-connection here in Canada, I believe it is the same one used in the kit sold at the diy store. I am contemplating taking apart the motorized volume control and swapping in the Alps pot that I have since they are both RK 27 size and pinout. I’m just looking for instructions or guidance on how to take the unit apart. Doesn’t appear to be accessible screws anywhere to separate the pot from the motor assembly. If anyone has some guidance on how to do this, or if they have done this successfully that would be greatly appreciated.
Thanks!
the first thing I did when I received the motorized volume control was to check the resistance to verify that is 50 K. One channel measured 49.2 ohms and the other channel measured 49.5 ohms. So unless some magical burn in is required then it seems as you said… that the pot itself is drek.
I have a 50 K stereo pot that I purchased from parts-connection here in Canada, I believe it is the same one used in the kit sold at the diy store. I am contemplating taking apart the motorized volume control and swapping in the Alps pot that I have since they are both RK 27 size and pinout. I’m just looking for instructions or guidance on how to take the unit apart. Doesn’t appear to be accessible screws anywhere to separate the pot from the motor assembly. If anyone has some guidance on how to do this, or if they have done this successfully that would be greatly appreciated.
Thanks!
Ok, I’m also contemplating desoldering and replacing the pot and motor with a complete Alps unit from Parts Connexion as the remote and muting functions of the board seem to work well. They only seem to carry 10K and 100K units. What would be the possible issues going with the lower or higher resistance pot?
https://partsconnexion.com/products/alps-10k-blue-velvet-stereo-motorized-potentiometer
Interestingly, this unit looks identical to the unit in the current remote.
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if your sources are of modern variety (low Rout), driving 10K attenuator is not going to be a problem
Hi PI, if you are asking if I’ve checked/measured the wiper to output, and wiper to input through its range from fully CCW TO CW I have and it seems to measure as a Log/taper pot should (at least according to the instructions I’ve read on line.
If there is any methodology that you can share that I can try out I’d be more than happy to try it out and learn something new while I try and figure this out.
Thanks!
A change like this (in frequency response) can easily be measured with a soundcard and REW, RMAA and other similar software or a sweep capable digital scope.
Thanks Zen Mod,
I’ll check the specs on my Dac/Tuner/phono pre etc and go from there. The reason I’d chosen the 50K pot initially is to follow the parts list and Papa’s design. If 10k works without issue than I may give that a try as well.
Thanks!
What size/value is the capacitor from input to ground (following the pot wiper)?
E.g. if it is 1000pF then 50% of 10k will have a cutoff frequency 31kHz (-3dB) but 50% of 50k will have just 6,4kHz.
That will definitely be audible...
https://www.learningaboutelectronics.com/Articles/Low-pass-filter-calculator.php
E.g. if it is 1000pF then 50% of 10k will have a cutoff frequency 31kHz (-3dB) but 50% of 50k will have just 6,4kHz.
That will definitely be audible...
https://www.learningaboutelectronics.com/Articles/Low-pass-filter-calculator.php
Hi Madis, I’d considered that as well. The difference from Saturday afternoon before the swap to Sunday afternoon is very apparent and audible. What the actual db attenuation is would be interesting to find out. I don’t however have an original frequency response. In this case though I know my ears are not lying to me. The “s” in words and lyrics is noticeably softer and almost sounds lisped if that makes any sense.
It does not matter, the current frequency response should be pretty flat to 20...30kHz, at 40kHz you might see some drop.
If it drops already at 20kHz then you have a problem.
Did you swap interconnect cables? My idea is that cable capacity form a low-pass filter. How is sound with pot maxed vol?
That is a very interesting thing for me to look at. Thanks so much for providing this! I’ll have a look at that as well.
Been there, done that. Usually amplifiers have ca 100pF there but some have "safeguarded" themselves with 1000pF. That is audible...
My Korg was built from the boards and transistor kit only before a full kit was available. I made mine with a 6 position rotary input selector but only wired it for 4 inputs. When I disconnected the inputs and output I made sure to keep them in order so as to not mix up the selector order so the exact same cable in any case are identical before and after. I have read on line that some people claim that attenuation from interconnect cables can occur for a little bit after cables are disconnected and reconnected. Whether this is “a thing” or not is beyond me.
My kit was assembled using the values found in this document from Papa. I’ll check my build against the list and see if your guidance may apply. Thanks again!