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AIYIMA A07 Volume potentiometer replacement Logarithmic

masmas112

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Joined
Jan 24, 2022
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Hello everyone,

I have been using my AIYIMA A07 for some weeks now, no complains about the audio quality, however I was annoyed by the volume knob, as it is difficult to control the volume on low volumes. I figured out that the potentiometer they use is linear, which explains my frustration.
I found this video in youtube from a guy changing the potentiometer. Youtube link
I had ordered (mouser.com) the potential meter he used, as well as 2 different units which had the same resistance (50K) and Logarithmic scaling:

RK09L12B0A31
Alps Alpine Potentiometers

RV122F-20-15F-A50K-0072
Taiwan Alpha Potentiometers

PTD902-2020K-A503
Bourns Potentiometers

To make the replacement as easy as possible have also created 2 different pcbs to use, as from factory the potentiometer is installed on a small separate pcb installed on some header pins.

I had ordered 2 from each type. I noticed directly that both the Alps Alpine Potentiometer didn't have the same resistance for the L and R channel, so one side was louder than the other.

Both the Bourns and Taiwan Alpha measured with in a couple of ohms between the L and R, the Taiwan Alpha is not aligning correct due the the height of the potentiometer. So I choose to use the Bourns, which I now have in use and are very happy with. It is a lot easier controlling the volume precisely, especially on lower volumes. I had to order a new knob, and make the hole in the front of the receiver a bit bigger for the new potentiometer to fit.
If anyone is interested here are the pcb designs:
https://easyeda.com/mschinkelshoek/aiyima-a07-volume-knob-pcb (the one i am using)
https://easyeda.com/mschinkelshoek/aiyima-a07-volume-knob-pcb_copy (incase someone really wants to use the Taiwan Alpha potentiometer, however it will not align correctly due to the height of the potentiometer)

You will need a new knob, as these three potentiometers are with a D shaft. I used the once mentioned in the youtube video link. here

This forum has been a lot of fun and helpful for me, so I am happy to give a way the pcbs, and the potential meters that I have laying here. I had ordered 5 of both pcbs, and i have now 9 knobs 1 Bourns , 2x Taiwan Alpha Potentiometers, 2x Alps Alpine Potentiometers left.

I will not be needing them. So if anyone is interested in doing this, send me a PM, I will send you the pcb, knob and potentiometers for free. Use at your own risk.
 

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Last edited:

dc655321

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Mar 4, 2018
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I've noticed substantial imbalance at low volume between L/R channels on my A07. Have not quantified it yet, but it's clearly audible...
Nice project!
 

xpop

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Mar 2, 2022
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Excellent initiative, today it seems that the logs curves for the volume adjustment are forgotten whereas it is a true necessity to correspond to the curve of sensitivity of the ear. Is it due to the very common use of digital encoders instead of carbon tracks? certainly!
 
OP
M

masmas112

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Joined
Jan 24, 2022
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I've noticed substantial imbalance at low volume between L/R channels on my A07. Have not quantified it yet, but it's clearly audible...
Nice project!
I checked to original pot, all the way to zero, it measures 7,5 and 3,8 ohms, other measerment at different setting 4,6K and 4,9K.
Compared to the bours, measured at zero: 1.52 and 1.48 Ohms.

I was really surprised by the Alps Alpine, which had a difference of more than 10 ohms per channel.
The best technical solution would be to use something like this: https://www.ebay.com/itm/192333906700?ul_noapp=true
However I foresee some alignment issues and you lose the stepless sound level adjustment, would be interesting to try, or even make pcb for, however it costs more than 40 USD to get it to be sent to my country. So that is why I stuck with the options from Mouser.
 
Last edited:

Kijanki

Active Member
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Dec 16, 2021
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Benchmark DAC1, I still have, has linear volume pot. I had to lube it to reduce static, but it worked only for a while, so I decided to replace it. I ordered exactly the same footprint 3 pots with plastic track, to select one that has best track to track match. One of them is almost perfect. I learned that Benchmark decided to use linear pots because of smaller channel to channel variations. I did not want to guess what resistors they placed across it to make it less linear (more logarithmic), so I replaced it with exactly the same type. I believe that volume progresses a little faster at the beginning, than my current DAC3 (digital pot), but it is not bad - very close. In general I tend to trust Benchmark products/choices - it is hi-tech company.
 

Zek

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Feb 17, 2018
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OP
M

masmas112

Member
Joined
Jan 24, 2022
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Instead of a potentiometer it is better to use DACT Type SMD Stepped attenuator, like this ...
Thanks, I had linked to a similar part in my previous comment. However yours is a lot better priced. I have bought one now. Will be interesting to try out. I am a bit sceptical by the limiting amount of steps it will have. As the Ayima A07 is a very powerful amplifier, and I only use the first 25 procent of the volume knob. So will be interesting to see if the steps will give me small enough steps.
 
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