Bottlehead Forum
Bottlehead Kits => Crack => Topic started by: Rossputin on June 11, 2018, 09:23:17 AM
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Hello all,
At the suggestion of many folks here and Doc B as well, I just received a new Alps pot.
What's the easiest and best way to make sure that I wire it correctly? In other words, what's the easiest and best way to know which terminal on the new pot matches up with which terminal on the pot that came with the Crack?
If I'm looking straight on at the three terminals, would the left one on the Alps definitely match the left one on the original?
Or do I just take out the original and try to figure out how to use an ohmmeter to determine which terminal is which? (Which I'm not sure I can do with absolute confidence...)
Thanks!
Ross
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It should be wired up exactly like the stock pot.
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Hi, new crack owner here. I've researched extensively and can't quite find a straightforward answer. Is this the correct Alps pot to use for the Crack? https://w ww.parts-express.com/alps-100kax2-100k-ohm-audio-taper-stereo-potentiometer-6mm-shaft--023-206
Just wanted to make sure it's the best fitting/most compatible and easiest to install Alps blue velvet pot for the crack. Also, does anyone have experience ordering one of these through parts express? Wanted to make sure it is not a knock off. Sorry about the URL, can't post links yet. Thanks!
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I can confirm that P.E. is first-rate! I live in the town where they are located so very familiar. I would think it's very safe.
I've been trying to find a reliable source for the lugged version, like this which would be really nice for soldering:
https://www.ebay.com/itm/Japan-Alps-Blue-Velvet-100K-Volume-Control-Potentiometer-Tube-Amplifier/361490171877?epid=1081861570&hash=item542a7e47e5:g:NggAAOxyn~pR0kbS
Not sure I trust this ^^ source however!
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Ah yes I didn't even realize the PE version was different. Yes I would prefer the lugged one as well!
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I have ordered lots of stuff from P.E. over the years with zero problems.
Just for reference I live in the US.
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Here's the factory website with the different RK27 pots:
https://www.alps.com/prod/info/E/HTML/Potentiometer/RotaryPotentiometers/RK271/RK271_list.html (https://www.alps.com/prod/info/E/HTML/Potentiometer/RotaryPotentiometers/RK271/RK271_list.html)
They all have pins.
If you buy an Alps RK27 with solder lugs, I have some pink $100 bills to sell you! (Note that we have had at least one fake over the years that sounded pretty good)
Mouser also sells these in the US.
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Haha I catch your drift! So while the lugs are a very nice addition, they're unfortunately not the real deal. Well thanks everyone for the clarification! I will most likely pursue the PE 100k with pins.
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The other thing that drives me nuts is seeing all those solid core wires wrapped around the pins on the RK27. Those pins are really not very sturdy and are designed to go into a PC board. You're likely to ruin the pot by anchoring wires to the pins.
Instead, spend a few bucks and buy a breakout board:
Breakout board (https://www.ebay.com/itm/1pcs-Gold-plated-stereo-Volume-potentiometer-PCB-for-ALPS-RK-27-16/272365690881?epid=1384322679&hash=item3f6a42a001:g:fVwAAOSwFV9X1nbh)
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Another option is a stepped attenuator using DALE resistors from Ebay.
Some consider these an upgrade to the Alps pots.
Can't commend on that because i never used an Alps pot.
I've used a stepped attenuator and was really happy with it.
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I have never been a fan of the Alps pot, not much better than the stock pot, if at all. The Audio Note pot is what I have been recommending for years, excellent pot for the money.
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That breakout board idea is awesome!
The parts express 100K ohm Alps is not labeled as an RK27. I wonder if it's the same as an RK27 Alps. Looks like it . . . but it is strange that "RK27" isn't referenced.
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The other thing that drives me nuts is seeing all those solid core wires wrapped around the pins on the RK27. Those pins are really not very sturdy and are designed to go into a PC board. You're likely to ruin the pot by anchoring wires to the pins.
Instead, spend a few bucks and buy a breakout board:
Breakout board (https://www.ebay.com/itm/1pcs-Gold-plated-stereo-Volume-potentiometer-PCB-for-ALPS-RK-27-16/272365690881?epid=1384322679&hash=item3f6a42a001:g:fVwAAOSwFV9X1nbh)
Awesome! Just ordered one today. Would've never known. Thanks so much for the link!
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That breakout board idea is awesome!
The parts express 100K ohm Alps is not labeled as an RK27. I wonder if it's the same as an RK27 Alps. Looks like it . . . but it is strange that "RK27" isn't referenced.
Yeah I had thought the same thing. Nowhere on the PE site is the manf part # from Alps mentioned. Tried to ask their online chat about it today...didn't know jack of course. I went ahead and ordered anyway. It's faster and cheaper than mouser and looks pretty identical.
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Hey, that's a better price for sure! I have never seen an RK27 labeled with "RK27", go figure!
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I went over to Parts Express today and got one of these 023-206s.
It's labeled "ALPS RK27" in the packaging. Just thought I'd let everyone know that!
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Awesome!! Thanks for sharing!
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FYI - My pot came in today. They put it in a yellow padded mailer and the pins punctured right through the plastic bag and the shipping mailer. Pins were all bent up! You'd think they would've thought about that by now :\
Anyway, just thought I'd share for anyone thinking of ordering from there, ask it be wrapped in bubble wrap or shipped in a small box
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That stinks. I am sure that P.E. will replace it, quickly! Shipping always makes me nervous.
I ordered the small breakout board from China so still waiting for that.
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I ordered the breakout board as well! What a great idea that is. Thanks to all of you for responding to my question and adding additional useful information. This is a great forum.
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Breakout board arrived. There are three rows of four pins roughly in the (horizontal) center of the board. Three pins from the ALPS go into three of the four holes in the top and bottom of the three rows. Kinda like this, using an X where an ALPS pin goes and an O where no pin goes:
XXXO
OOOO
XXXO
With this in mind, how do you experts recommend I wire this, and do you think I should get some little terminal blocks for the edges, or just solder directly to the board?
Thanks for any help!
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This link/picture helped me on a past non-BH project.
(I soldered to the pins on that one!)
I was hoping to follow the traces on the board, once I get, it and figure it out.
http://www.diyaudio.com/forums/class-d/280137-wiring-alps-rk27-50k-potentiometer.html
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If you got the break-out board PB linked, then there is only one way it can be mounted (as shown in the listing). Screenprint upwards & the RK27 centered.
Terminal blocks are ok in power supplies, but my preference is not to use them in the signal path.
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There's a labeled "IN" side and an labeled "OUT" side.
The IN" side receives the signal from the RCA jacks. L is the white wire. R is the red wire. G is the black wire. All holes labeled G on that board are connected together, so you don't (and shouldn't) add jumpers if one isn't used.
On the "OUT" side, R is the red wire going to the 9 pin socket, L is the white wire going to the 9 pin socket, and the black wires hook up to the soldered pads labeled G.
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I'll just add that the picture shows that all of the ground connections have a dashed circle around the holes. I assume that the ground connections in the center 4-hole portion of the board are for jumpers? Or in other words the alps pins do not go into those holes?
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I'll just add that the picture shows that all of the ground connections have a dashed circle around the holes.
Yes, the board uses a small ground plane for all the ground connections.
I assume that the ground connections in the center 4-hole portion of the board are for jumpers? Or in other words the alps pins do not go into those holes?
What jumpers? Which holes?
It looks like the board might fit a few different pots. I wouldn't solder any wires to any of the holes other than the ones on the edge of the board where the terminal blocks go.
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Yes, most of those boards are also designed for the RK16 pots, which has a different pin layout.
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Which holes?
BP, the link you provided for a breakout board shows 3 rows of 4 holes in the center of the board (not the IN or OUT outer holes). The first/left holes in those 3 rows all indicate they are for ground. So my question is are those hole meant to be used for jumpers or for the ground pins of the pot? Sorry for the confusion.
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So my question is are those hole meant to be used for jumpers or for the ground pins of the pot? Sorry for the confusion.
Since they are all connected together through the ground plane of the board, you do not need to add jumpers. They are the ground pins of the pot.
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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.)
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Often times the more expensive pots have better low level tracking.
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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.
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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!
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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
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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.
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A pair of tin snips is also a handy tool for trimming PC boards.
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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.
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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!
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Thank you for posting the pics OP! Glad you got it up and running. Gives me an idea of what to expect.
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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!
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marked
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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.
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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.
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If you rotate the pot, does it have a center detent?
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I does not have a center detent
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It could have something to do with the wire leaving the pot and going to A7. I see way too much jacket stripped off on the A7 end, and if that bare section touches other connections, then you'll lose the channel.
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I didn't mess with the connection at a7 at all in the switch. I just inspected it and it's not touching anywhere. That said I can make a new wire for that and solder it on to make absolutely sure. Any other ideas on what might make me lose the channel.
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I didn't mess with the connection at a7 at all in the switch.
That wire had to move to change the pots out. It is literally connected to the pot!
Any other ideas on what might make me lose the channel.
I would perform another voltage check to be 100% certain.
Beyond that, you can temporarily solder in a little jumper wire between A2 and A7. That will sum the outputs of the pot and could provide some useful information. If you happen to lose both channels when you do that, be sure to rotate the volume control through its entire rotation to see if things come back in part of the rotation.
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New wire to A7 and a bit of fiddling fixed it. Thanks!