Hi.
As I had my Arcam Delta 290 integrated taken apart and I was not sure of the audio quality, I took the Alps 10KAX2 motorised potentiometer apart and checked the possibility of cleaning it. Unfortunately it seems to be not openable unless one would risk to break something. I sprayed it with contacts cleaner
I also took measures to compare the left and right channel. As recommended here, would you throw it away?
Attached are the measures of resistance. 1 to 25 are progressive positions of the shaft, non linear.
![CropperCapture[12].jpg](https://www.diyaudio.com/community/attachments/croppercapture-12-jpg.1263344/ "CropperCapture[12].jpg")
As I had my Arcam Delta 290 integrated taken apart and I was not sure of the audio quality, I took the Alps 10KAX2 motorised potentiometer apart and checked the possibility of cleaning it. Unfortunately it seems to be not openable unless one would risk to break something. I sprayed it with contacts cleaner
I also took measures to compare the left and right channel. As recommended here, would you throw it away?
Attached are the measures of resistance. 1 to 25 are progressive positions of the shaft, non linear.
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Your measurements seem to fail to account for a difference in the overall resistance of each of the elements, i.e., one side of your 10K pot could be 9647 ohms versus 10120 ohms on the other side. For yours, you could measure the total resistance of each channel and divide your readings by that to get a percentage of attenuation and graph that.
I use TKD pots quite often, and had one with a noticeable difference. TKD cautions not to rely on resistance measurements (see here for more info on TKD). At any rate, for mine (it was brand new and I hadn't soldered it yet), I ran 1V from a bench supply into the pot and measured the wiper to ground. It was indeed off, and I emailed my findings to PartsConnexion (who I had bought the pot from) and they replaced it. The replacement was fine. The link i provided uses a 1K signal to do the same.
I use TKD pots quite often, and had one with a noticeable difference. TKD cautions not to rely on resistance measurements (see here for more info on TKD). At any rate, for mine (it was brand new and I hadn't soldered it yet), I ran 1V from a bench supply into the pot and measured the wiper to ground. It was indeed off, and I emailed my findings to PartsConnexion (who I had bought the pot from) and they replaced it. The replacement was fine. The link i provided uses a 1K signal to do the same.
Even the measurements posted are within typical low cost pot tracking, other than below setting number 3,
which won't ever be ever used. Of course you can get better tracking, especially from a switched resistor control.
Bear in mind the line stage gain tolerance may be large enough to shift the results significantly.
which won't ever be ever used. Of course you can get better tracking, especially from a switched resistor control.
Bear in mind the line stage gain tolerance may be large enough to shift the results significantly.
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It appears that you're using Excel or similar spreadsheet program. I recommend plotting dB attenuation for each channel and plotting both curves and perhaps the difference in dB.
Eg:
Left(dB) = 20*LOG10(Lresistance/9545.62)
Right(dB) = 20*LOG10(Rresistance/10099.51)
By my eyeballs, the pot seems OK.
Eg:
Left(dB) = 20*LOG10(Lresistance/9545.62)
Right(dB) = 20*LOG10(Rresistance/10099.51)
By my eyeballs, the pot seems OK.
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Picking position '10' as an example and the imbalance effect on a signal.
And in db
And for position '5'
And position '1'
Conclusion... outstanding channel matching.
And in db
And for position '5'
And position '1'
Conclusion... outstanding channel matching.
Thank you Pars!
I tried what you said. Rating the resistance to the channel maximun makes sense but the difference is not much. Anyway thanks for the parts connexion supplier too. It might come handy
Excel is able to make the y-axis logarithmic, but better have a calculated column and plot that in a linear scale. It's ms...
Well that's pretty a good result @Roppu...
yes, imbalance issues are frequent in the first degrees of rotation of the stereo volume pots, when they are ageing, or even when new.
It seems that synchro dual gang audio pots are less stable than linear ones with the time passing by - at least that's what I notice.
That's why I opt for separate controls sometimes on my DIY units :
T
yes, imbalance issues are frequent in the first degrees of rotation of the stereo volume pots, when they are ageing, or even when new.
It seems that synchro dual gang audio pots are less stable than linear ones with the time passing by - at least that's what I notice.
That's why I opt for separate controls sometimes on my DIY units :
T
Bass (lower) on top, Treble (higher) below.
How would it sound upside down?
How would it sound upside down?
What is a synchro pot? A log one? I love the look of your amp.
For the records, as I started with the diagram of the left/right inbalance... Correct one:
What is a synchro pot? A log one? I love the look of your amp.
For the records, as I started with the diagram of the left/right inbalance... Correct one:
![CropperCapture[5].jpg](https://www.diyaudio.com/community/attachments/croppercapture-5-jpg.1264180/ "CropperCapture[5].jpg")
Thanks @Roppu ! 🙂
Sorry : by synchro pot, I meant a single-axle, dual-section pot, with each section following (tracking) the other as close as possible in taper, being A (Audio=Log) or B (Lin). It seems - to me at least - that B (Lin) pots are more accurate than A (Log) on this point.
Imbalance percentage speaks less to me than imbalance gain in dB. On vintage instruments, I consider a variation contained in a 3dB channel to be very good, not to say excellent (many brand new modern gear don't even go that far !). Within a +/-3dB variation channel, it is still good in practice. It's not rare to have larger dB gaps at the start of the taper (first degrees of rotation).
That said, the curve in % you show above doesn't seem alarming to me : the most important section being the start and the rest before the max - where we do not go very often, right ? 😎
Well... Why not ? 😉
T