Pars

^ That doesn't match what Kerry did on his boards from L-R top (or front): 1 - 2 - 3 - 4 Gnd open output input (wiper)

Nope. Wire as labeled on the board I1-I4, so normally L+/L-/R+/R-. O1-O4 go to the board inputs in the same manner. Or be different and do R/L

Yeah, I hadn't looked at that. Isn't it $2.26 for a package of 100 Guess not...

Happy Birthday Jim! Hope you are enjoying things in Florida!

Good info from Gordon Rankin. Kind of a big leap of faith with the writer making this statement however: Bringing it all back home, the iFi iPurifier 2 likely improves the sound of the Sonicorbiter SE because it minimises transmission errors by making lighter work for the Mytek Brooklyn’s USB receiver chip. I would think that the purifier may be changing the error(s), but whether it is actually minimizing anything can't really be determined without looking at it as Mr. Rankin does.

From looking at Kerry's layout, it looks like he is connecting pins 1 (gnd), 3 (output?) and 4 (input) on the pot. I assume that I am looking at the right pot (Alpha 21mm 3RP-2142G, from Alpha in Oxnard, CA)? There is also a Taiwan Alpha and a Korean Alpha, but the pots I find from there aren't 4-ch, look nothing like this one, etc. The data I found on the CA Alpha company website just shows pins 1-3 on their schematic diagram, so I assumed the 4th pin (right side row) were loudness or unconnected. I also made the assumption that the pin numbering starts from the left lower corner: 13 14 15 16 9 10 11 12 5 6 7 8 1 2 3 4 If anyone has the correct datasheet or a link... this is what I was looking at. http://alphapotentiometers.net/html/21mm_pot_4.html

I defined a library part for the Alpha 3RP pot and played around with it on the current 3 pot board to see what the pin layout was like. As you can see from the pic below, it might be possible, but there would be some drill overlaps, and the pot would have to be offset 2mm due to the 4 pins per row instead of 3.

Anything is possible, but probably not happening. I still haven't figured out what the 4th pin per row is for and the datasheet doesn't seem to define it. I'll have to examine the gerbers for Kerry's board more...

That thing is sweet Kerry! Really nice job. What layout software were you using? Also, what pot is this set up for? Alpha? Would a TKD601 work? Ooops, just figured out what pot you are using, so no go on that

Like these?

I'm still waiting to hear from seeed regarding any issues with the slots and drill holes. I really don't know why someone would want the 2 TKD pot only board when the one that does all 3 is the same size/price. Also, I haven't updated that board in a few days. As for channel / gang mapping on the pots, this version only swaps gangs 3 and 4 on the RK27 (ch 3 goes thru gang 4, ch 4 thru gang 3 of the pot). Otherwise, straight ch # to gang #.

Still waiting for seeed to get back to Michael or I regarding any problems with the board, but based on some feedback/suggestions on an eagle support forum, this should be close to final. I placed the Molex/Phoenix jacks right on top of one another, which is the way I do it when I add these to an existing board. Slots are now filled rectangles rather than hollow rectangles, so should be easier for seeed to figure them out. For the bad pin overlap on row 3 of the Alps and row 4 of the CP601 center pins, I added a milled round slot and rectangular pads to top/bottom. For the overlap on row 1 center pins of the CP2500/Alps RK27, I added a milled slot. Board is 46.6 x 35.4 mm. I also redid the 4CP601 only board with the overlapping connectors. Of course I'm probably the only one who cares about these far superior connectors

Very nicely done! Who/where is the case from? Agree that the wiring could probably be cleaned up a bit, maybe a pcb for the pot wiring would help? Routing down the center like you did is good though.

Happy Birthday!

hanks UFN! I did a layout that supports all 3 pots (4CP601, 4CP2500 and Alps RK27114). Similarly to Birgir's layout, this one would allow cutting to support a stereo pot if desired. 46.5 x 35.2 dimension

Not true.

No. Footprint isn't close to the CP2500. Edit: BTW, anyone have a datasheet for the quad RK27? Can't find one, and Alps barely acknowledges they do a quad version of the RK27 (RK27114).

As I feared, I can't go larger on the CP-2500 pad size without clearance issues between the pads noted in a previous post. Just a bad relationship between the 601 and 2500 pad locations. The only other think I could do would be to define the pads in the part as SMD pads, which I can control the x/y size and roundness on. You have to place these on both the top and bottom layer, and then drill them (or the slot) to get them to do a through hole part and plating. Might confuse Seeed. Here is the new gerber file(s) for the CP601 only board using 1.1mm drill on the pot holes. No change in board size or anything else. The dual board will not change size either once we have determined slot size. TKD 4CP601 only mod.pdf

My intent was for the board to support both old and new pots. My concern is what is the convention for how much extra space to leave, i.e., what will the finished dimension of a 3.1 x 8 mm slot be after thru-plating and manufacture. I ran across the attached document the other day regarding IPC-2222 and IPC-2221 standards. Level A is for general production, and is what I think I should shoot for, but results in the most additional and the largest pad size. Unfortunately, it doesn't discuss slots. For the holes and pads for the CP601, the pins are 0.8mm. So, for Level A, the hole size would be: Minimum Hole Size = Maximum Lead Diameter + 0.25mm (for Level A of IPC-2222) 0.8 + 0.25 = 1.05. This isn't a std. drill, so 1.1. I already have this at 1mm, so can bump up. Pad Diameter = Minimum Hole Size + 0.1mm + 0.60mm (for Level A of IPC-2221) 1.1 + 0.1 + 0.6 = 1.8mm. Pads are already at 1.934, so good there. For the slots for the CP2500, I think I should bump them to 3.2 x 0.8mm If you could ask Seeed what the approx. finish dimension of a 3.1 x 0.8 and a 3.2 x 0.8mm slot would be, I'd appreciate it. I don't think I could go beyond the 3.2, as the pad would be getting too small, and there isn't room to bump the pad size up much, at least at Eagle's std. values. Let me know what you guys think. http://www.pcb-3d.com/knowledge-base/pth-dimensions

If you can ask if they can measure one, that would be great. Thanks!

OK, changed the slots from 2.6 x 0.8 to 3.1 x 0.8. MLA: can you check with your TKD contact regarding the pin size? Michael: can you check with seeed to see what the final dimension for a 3.1 x 0.8mm slot will be once plated? I was just guessing in terms of final dimension and how much additional size to plan for on the slots. For the CP601, the datasheet shows the pins at 0.8mm. On the part I created in Eagle, I used a 1mm drill, so we should be good there i think. I could up the drill to 1.1 if needed. Going any larger on the pad size would risk clearance issues between pins 4, 6, 7 and 9 on the CP601 and 2 of the output pads on the CP2500.

I was looking at Thorsten Loesch's Analogue Addict's Phono Preamp, originally posted here, updated on the Pub in 2004/2006 or so, and then again on diyhifi.org in 2012. I can't find anything beyond what is in the thread there (all links/images are dead). Seems interesting though, and pretty cheap to build. It does have an add-on portion for MC, but is geared towards MM carts. Thorsten advises P-P build instead of doing a PCB, and thinks that deadbug on copper would be the best way to do this. Something I've never done before. This needs a pair of OPA637s, which at current pricing I would be reluctant to solder directly to. If anyone happens to have more up to date info on this I'd appreciate anything I could get. Apparently he had made parts recommendations (based on more current parts), etc. I sent him a PM on diyhifi, but I would be surprised if he answers it. Maybe do a teflon PCB

I'd be interested in some 2SJ74s depending on grade. Or maybe some 2SK170s in addition, though I still have a number of those in BL grade IIRC.

For the dual CP401/CP2500 pot board: I went downstairs and measured the pins on a 2CP2511 I have (never used), and the width on the pins was 3mm, not the 2.5mm shown in the datasheet. The datasheet you guys sent does show 2.5mm, but an older datasheet that I had shows 3mm, so they must have changed these at some point. I think I should enlarge the slots to 3.1 x 0.8mm just in case, and to accommodate older pots. Thoughts? I attached both datasheets. TKD cp2500ps-e.pdf 2CP2511.pdf

I think I would prefer to stick with SS. My cart currently is an AT 440mla MM, 4mV so I don't need anything that will handle a LO MC. I was looking at AudioSector, but that one appears to be geared towards LO MC. The table is my old Thorens 320, so nothing special there.