ALPS (RK163 Series) with Loudness TAP (4 Terminals) 40mm shaft length and single D-Shaft - Custom Made or not ?

[tiefbassuebertr]

ALPS Stereo Potentiometer for Volume Control (RK163 Series) with Loudness TAP (4 Terminals) 40mm shaft length, single D-Shaft (Flat, not slotted, not knurled) - standard part or custom made ?

The attached PDF do mentioned the meaning of the individual digits behind the naming "RK163".
According this the order code of wanted version is RK163 F40 C0
This don't correspondent with this sheet:
https://tech.alpsalpine.com/e/products/category/potentiometer/sub/01/series/rk163/
go to
https://tech.alpsalpine.com/e/products/detail/RK16312A0B85/

The integrated amplifier Harman HK610 use a 4-tap volume control from the Alps RK163-Series (30KBX2).
An attached picture - found on the web`under
https://imall.com/product/1pcs-lot-...ts/aliexpress.com/32788254523/568-1853866/en?
- show exact this potentiometer. Another version too, but with additional motor - found on the web under
https://de.aliexpress.com/item/32851918753.html
Obviously identical potentiometer is implemented in the motorized version from this company:
https://vicko.ecer.com/products.html
go to the attached image No 2-5

Harman's order code is "5113-S20043003" - go to service manual under
https://web.archive.org/web/20130323122720/https://diagramas.diagramasde.com/audio/HK610 sm.pdf

Where I can order a potentiometer in this 4-tap outline (30KBx2 or maybe 50KBx2 or 100KBx2) ?

The good known blue Alps RK27112 was offer in a 4 tap version for loudness - go to
https://www.aliexpress.com/item/32860672317.html?gatewayAdapt=glo2deu
and
https://www.iwistao.com/en-de/produ...japan-alps27-type-100k-hifi-diy-free-shipping
and
https://www.diyaudio.com/community/threads/alps-rk27-50k-with-4-pins-in-row.391119/
unfortunately not with the right shaft length and D-shaft (flat shaft). Another disadvantage is the need for more space.

P.S.: Luxman's L190 and L210 use also the outline from image No 1 with additional loudness tap for it's volume control, but 100KBX2 instead 30KBX2 resistance (Stock-No 18T56665F01) - so I guess, no custom made version.

 

[Johan_vd_W]

Frustrating to see that you've also ran into the trouble of finding good quality center tapped (loudness tapped) volume controls. In my recent amp build I couldn't find this myself and ended up ditching the loudness all together. I only could find these on general Chinese marketplaces such as what you found yourself.

What I did find is that most (all?) ALPS with blue casings and 8 pins seem to be fake. Think there was a previous thread on that as well. But who could say for sure? For instance, I found this link: https://theaudiocrafts.com/ALPS-RK27-A50KX2-Potentiometer-with-Loudness-Tap. Or this one which is definitely fake (see font on back) http://www.ampmart.com/en/productview.asp?sid=1153

The good kown blue Alps RK27112 was offer in a 4 tap version for loudness - go to
https://www.aliexpress.com/item/32860672317.html?gatewayAdapt=glo2deu
and
https://www.iwistao.com/en-de/produ...japan-alps27-type-100k-hifi-diy-free-shipping
and
https://www.diyaudio.com/community/threads/alps-rk27-50k-with-4-pins-in-row.391119/
unfortunately not with the right shaft length and D-shaft (flat shaft). Another disadvantage is the need for more space.

I noticed in your link that some of these are only a piece of circuit board to add loudness to the 2x3 pin normal Alps volume knob (at least the red one is). So that wouldn't be the same as a center tap.

Anyway, good luck! Hope you find a matching solution!

 

[tiefbassuebertr]

According the images under
http://www.ampmart.com/en/productview.asp?sid=1153
this is a stepped attenuator - i. e. a rotary switch and SMD resistors.
Under
https://tech.alpsalpine.com/assets/products/catalog/rk271.en.pdf
https://tech.alpsalpine.com/e/products/detail/RK27112A0A16/
there are not to find such a version.
Obviously this part under
http://kit-amp.com/alps-rk27-volume-control-loudness-en
is also a stepped attenuator and not from Alps.

 

[tiefbassuebertr]

While troubleshooting procedure I note, that the loudness tap of this potentiometer do not support any loudness effects in Harman's model HK610, because only a 1K5 resistor goes to GND and no additional capacitor is in use - go to the attached images and to the schematic from service manual under
https://web.archive.org/web/20130323122720/https://diagramas.diagramasde.com/audio/HK610 sm.pdf

Maybe the aim is only to optimize the subjectively perceived increase in volume as a function of the angle of rotation.
Are similar results possible even on usual potentiometers with only three terminals if one connect an appropriate resistor on the center tap (= output of potentiometer) ?

 

[jean-paul]

Just reading this thread while realizing one buys a new amplifier that outperforms old amplifiers for a lower price than a single real good quality potentiometer costs (and caps etc. still have to be replaced). Crazy really.

Anyway I think you'll have to adapt to what can be found and if that is a knurled shaft version then also the volume knob will need to be replaced. That comes with repairing/servicing old stuff. The RK27 is a fine replacement for the older Alps carbon potentiometers. The normal shaft version can be made D shaft with a good old precision file. Or... cut the D shaft from the defective potentiometer and connect it with an extension piece to a new normal shaft RK27. Solves the 40 mm length as well.