I have to replace the volume control on my old SU-V8 amplifier due to severe mistracking between channels at lower volume levels, so I figured why not add a remote volume control while I'm in there.
I ordered a kit from ebay which uses a RK168 motorized Alps pot and also has power relay. The stock unit uses basic carbon comp elements, which aside from tracking poorly (had to turn balance control almost to 3 o'clock to even it out) otherwise sounded ok.
This is the kit I ordered and then will be swapping the RK168 pot for a higher grade RK271- Remote potentiometer kit with power switching
I'll post more info as I receive more of the parts. I also have added a buffered, balanced pre-out using DRV134 chips. They actually sound very good despite being op amp based.
The main reason I'm doing this is because of the excellent MC phono stage the amp has along with its gutsy double transformer dual mono power amp design.
I ordered a kit from ebay which uses a RK168 motorized Alps pot and also has power relay. The stock unit uses basic carbon comp elements, which aside from tracking poorly (had to turn balance control almost to 3 o'clock to even it out) otherwise sounded ok.
This is the kit I ordered and then will be swapping the RK168 pot for a higher grade RK271- Remote potentiometer kit with power switching
I'll post more info as I receive more of the parts. I also have added a buffered, balanced pre-out using DRV134 chips. They actually sound very good despite being op amp based.
The main reason I'm doing this is because of the excellent MC phono stage the amp has along with its gutsy double transformer dual mono power amp design.
Please note that replacing potentiometers for potentiometers usually ends up with having the same issues.
Similar kits exist based on relays.
Similar kits exist based on relays.
The tracking of that potentiometer should be checked before installation. Especially the first half of the rotation. A friend of mine bought something similar for a tube preamp, and it worked great. These are all fake Alps.
I prefer Chinese rotary switches with SMD resistors. Firstly, they sound better than the original Alps RK27, secondly, the tracking is perfect.
I prefer Chinese rotary switches with SMD resistors. Firstly, they sound better than the original Alps RK27, secondly, the tracking is perfect.
@NIXIE62 I'm not using that pot in the picture, just the control portion along with an RK27 blue velvet model.
I agree with you guys on the tracking issue with most stereo potentiometers. I always check this before install and so far haven't had any with more than a few percent mis-tracking in the lower 3rd to half area of rotation. They also sound decent for the cost and certainly sound better than most carbon comp units. The cheaper RK168 (seen in that kit I posted) isn't that great in that regard, which is why I'm replacing it with the better RK27. Both motors on these pots are the same voltage and current, so they interchange.
I used to buy the Alps RK27 knockoffs with the rotary switched SMD resistors and had decent luck with those, but they require alot of rotational force to operate and only had 24 steps. The other issue these recently started having is the channels being out of sync. Good concept but terrible QC.
@jean-paul It will cost at least $100 for a decent series stepped attenuator with at least 48 steps. The relay based attenuators are physically too big to fit inside an integrated amp unless there are smaller units available which I'm not currently aware of. I also wanted to retain the original volume knob fitment and found a version of RK27 with the correct shaft style and length. So far I haven't had any issues with the tracking on the RK27 pots and honestly believe they sound pretty good when used correctly.
I agree with you guys on the tracking issue with most stereo potentiometers. I always check this before install and so far haven't had any with more than a few percent mis-tracking in the lower 3rd to half area of rotation. They also sound decent for the cost and certainly sound better than most carbon comp units. The cheaper RK168 (seen in that kit I posted) isn't that great in that regard, which is why I'm replacing it with the better RK27. Both motors on these pots are the same voltage and current, so they interchange.
I used to buy the Alps RK27 knockoffs with the rotary switched SMD resistors and had decent luck with those, but they require alot of rotational force to operate and only had 24 steps. The other issue these recently started having is the channels being out of sync. Good concept but terrible QC.
@jean-paul It will cost at least $100 for a decent series stepped attenuator with at least 48 steps. The relay based attenuators are physically too big to fit inside an integrated amp unless there are smaller units available which I'm not currently aware of. I also wanted to retain the original volume knob fitment and found a version of RK27 with the correct shaft style and length. So far I haven't had any issues with the tracking on the RK27 pots and honestly believe they sound pretty good when used correctly.
No. They are small and way cheaper. Check the ones with Omron bistable relays on Aliexpress. They are 64 steps.
How long do those latching relays last? I thought they were prone to failing early compared to standard momentary contact relays. Hmmm...
They are delivered with real Omron relays. They’ll last longer than a potentiometer. I built one but got a balanced input amplifier a day later.
I found this one with remote control. You wouldn't need the display since you are retrofitting the SU-V8.
https://www.aliexpress.us/item/3256...MTc0MTEzNjcyMS41OS4wLjA.&gatewayAdapt=glo2usa
https://www.aliexpress.us/item/3256...MTc0MTEzNjcyMS41OS4wLjA.&gatewayAdapt=glo2usa
While I agree that a relay based attenuator would sound better than a traditional pot, the installation of a pot would be much simpler and straight forward.
The loudness circuit is also variable depending on the volume setting and I dont want to lose that feature, so that also favors the use of a simple pot.
The volume knob has a divided scale and an infinite rotary encoder wouldn't show the absolute physical volume setting on the scale. Without some other form of display, the volume status wouldn't be visible. Thats kind of important IMO.
The digital display that comes with the step attenuator would be the only way to determine the physical volume setting, but I'd have to hack up the front panel of the amp to make that type of display work. A circle of LEDs on the inside perimeter around the volume knob right behind the front panel would work, but that requires more engineering.
These reasons are why I prefer the mechanical pot over the relay attenuator. I know alot of people claim the resistor style attenuator sounds better, but I have had excellent results from the RK27 Alps pot given the elements match closely. I've only had issues of this type with the lesser RK168 Alps and some other brands. Noble and TKD are also a good brands and perform (to my ears) very close to a discrete resistor style step attenuator. The only thing I felt that was significantly better than any of these other volume controls was a Dale RN55 equipped mechanical step attenuator.
The loudness circuit is also variable depending on the volume setting and I dont want to lose that feature, so that also favors the use of a simple pot.
The volume knob has a divided scale and an infinite rotary encoder wouldn't show the absolute physical volume setting on the scale. Without some other form of display, the volume status wouldn't be visible. Thats kind of important IMO.
The digital display that comes with the step attenuator would be the only way to determine the physical volume setting, but I'd have to hack up the front panel of the amp to make that type of display work. A circle of LEDs on the inside perimeter around the volume knob right behind the front panel would work, but that requires more engineering.
These reasons are why I prefer the mechanical pot over the relay attenuator. I know alot of people claim the resistor style attenuator sounds better, but I have had excellent results from the RK27 Alps pot given the elements match closely. I've only had issues of this type with the lesser RK168 Alps and some other brands. Noble and TKD are also a good brands and perform (to my ears) very close to a discrete resistor style step attenuator. The only thing I felt that was significantly better than any of these other volume controls was a Dale RN55 equipped mechanical step attenuator.
I prefer cheap step attenuators with tiny SMD resistors. They sound better to me than the ALPS RK27. The only thing is that these cheap ones only have 21 step, but I don't mind that. I use a buffer without amplification, the range of the potentiometer practically goes from 0-60%. The regulation curve is good, I have no problem with it. Excellent sound quality, perfect tracking between channels, and low price led me to this solution. Unfortunately, such step attenuators are not suitable for motorization.
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Those smaller round body attenuators are nice, especially for the money. I wish they made them motorized somehow.
I received the remote kit today and it looks well thought out. The wiring is short though and I have to extend the sensor diode. Theres also a mute function but I would need an extra drive logic level switching transistor to activate a relay for that. I could also try a pair of FETs that short the signal to ground, like some CD players and DACs also do.
I received the remote kit today and it looks well thought out. The wiring is short though and I have to extend the sensor diode. Theres also a mute function but I would need an extra drive logic level switching transistor to activate a relay for that. I could also try a pair of FETs that short the signal to ground, like some CD players and DACs also do.
@stocktrader200 I always aim to be in the 12 to 3 o'clock range with the volume setting for best channel balance.
I received all the pots I ordered and so far the worst tracking units are less than 0.5% out balance. The pots are 50KAX4 and 100KAX2, which are essentially logarithmic........ the worst kind for channel balance.
These are BTW all RK271 series with motorized shaft. I prefer the Noble black coated aluminum units, which are obviously superior to the blue velvet Alps pots, but are incredibly hard to find for a reasonable price nowadays. I still have a stash of 10k stereo Noble which are too low resistance. I need at least 50k.