Wiring replacement pot (Alps)

[Paul Birkeland]

Often times the more expensive pots have better low level tracking.

[Laudanum]

Cool beans regarding the circuit board.  I used 22 gauge from the RCA inputs to the Alps when I built my Crack several years back.  It was easier to wrap the pins with the smaller wire and it's been fine.  But, I went ahead and ordered a board anyway.   I'll end up doing the "upgrade" after I get the board and get bored.   I knew that these boards existed and meant to get one but forgot about them.  I was even thinking of drilling and etching my own at one point (I can make simple boards).    But thanks for the reminder. 

[fromnowon]

A very fundamental question for you experts: Why do so many, including Doc B, believe that upgrading the volume pot is one of the first and best upgrades for the Crack (other than speedball)? (I'm not saying I disagree...I don't know enough to have an opinion. It's a sincere question with no subtext!) Can you tell me just what the benefit is of an upgraded pot? (And I'm in Colorado, so please no upgraded pot jokes.)

Well, I'm far from an expert but the alps pot is noticeably smoother and less "scratchy" feeling than the stock pot.  Also seems well-sealed so I suppose it will be less likely to get dusty over time and require deoxit treatment etc.  It feels high quality like vintage audio equipment with a smooth, hydraulic feel when you turn it.  Personally I adjust the volume a lot when listening so there's a lot of interaction with that control! 

[Rossputin]

UPDATE: ALPS pot successfully installed! The wiring instructions above from "Caucasian Blackplate" are perfect. One word of warning: After installation, I found the width of the breakout board to be about 1/8" too wide for the assembled Crack to fit back into the base, so I used a Dremel tool to grind away about that much of the outer edge of the board (while it was fully installed, soldered, etc.) There was plenty of room to do that without impinging on the solder pads.  Now it's all good!

BTW, I didn't necessarily get the rock-bottom price but as I believe there are Chinese fakes out there (based on how many "ALPS" pots can be purchased on eBay from China), I wanted to make sure I got the genuine article. So I bought here...price includes free one-day shipping, which makes the price very much in line with other sellers and better than some!
https://www.arrow.com/en/products/rk27112a00ak/alps-electric

[JLDub]

Hmm, that's actually not bad at all! Right about what I paid for the one from parts express + you got the one day shipping. Rock on man!
Request: would you mind posting a couple of pictures of yours now that it's all wired up? Would love to see an example before I get started. My breakout board finally arrived from China.

[Paul Birkeland]

A pair of tin snips is also a handy tool for trimming PC boards.

[Rossputin]

Pics as requested...not sure if this will insert them as images in the post or if you'll have to download them...just used the attachment function because I can't see any other way to insert an image.

Anyway, in a couple of the pics you'll see where I had to grind away a bit of the outer edge of the breakout board. It's kinda ugly but perfectly functional and nobody's gonna see it anyway outside of these pics!

You'll notice that I attached the "in" wires on one side of the board and the "out" wires on the other side of the board. I actually don't even think any other way would have been possible with wires cut to length of initial build instructions, nor was there a need to do it any other way than this.

[fromnowon]

Thanks!  That will help me a lot.  Now I know what to expect when I get there.

As an option, I wonder if we could have cut a slot in the side piece to accommodate the edge of the board.  (table saw kerf or two I mean - I'm lucky to have a table saw). 

Of course my base is glued and finished now so that's not very practical! 

[JLDub]

Thank you for posting the pics OP! Glad you got it up and running. Gives me an idea of what to expect.

[fromnowon]

Just for the record -
The Parts Express  023-206s "ALPS RK27" has a 25 mm shaft.
The stock pot has a 15 mm shaft which works perfectly with the stock knob of course (I think the knob is very cool by the way).
I just clamped the shaft on the end I was going to cut in vice grips and cut 10 mm off with a hack saw.  It was easy to cut through the aluminum shaft.  Then filed it smooth. 
Thanks for all the advice!

[cddc]

marked

[ItsAllInMyHead]

Thanks to the OP, Doc, Paul, B, and the group.  Just swapped mine this morning.

I went with another breakout board thinking I wouldn't need to trim it.  Nope.  Still a smidge too big on the base-side.  I chose to notch the base vs. clip the PCB.  I was worried I'd damage the board, and the notch doesn't need to be as deep as the top edge of the base.  In other words, it's not visible once the top plate is in place.  It's just a notch into the inner "lip".

If it's useful, this is the board I used.  Happy to post pics, but the process seems to be very well-covered by previous posters.  I needed to add a bit of length to the output right channel and output ground wires. 

https://www.ebay.com/itm/1pc-Adapter-PCB-Board-for-ALPS-RK16-RK27-Potentiometer-Audio-Amplifier-Pre-AMP/323385609326?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

The benefit I was looking for (achieved) was allowing me to listen at lower volumes with proper channel balance when I feed it with a slightly higher (2.5V vs. 2.0V) source.  It works for me.  Personally, I don't notice any change in the overall sound across levels, but YMMV.  If it's more durable / longer lasting due to design, then all the better.  It is a bit smoother in rotation, which I also like.

Once again, thanks to the Bottleheads and all those that contribute to the fun.

[ryburdman]

Just installed a new apls pot i purchased from Mouser onto a PCB then into the amp. The audio worked fine with the original pot. Now if have no audio in the right channel I have checked the voltages all check out.

[Paul Birkeland]

If you rotate the pot, does it have a center detent?

[ryburdman]

I does not have a center detent