Quick Alps Blue Question

[A Jedi]

Will be replacing the stock pot for an Alps Blue - I assume the 100K Ohm version is what I need?

[Paul Birkeland]

Yes, 50K-250K logarithmic.  Be sure not to buy the MN taper pot.  Be sure not to buy a pot with solder lugs (that would mean it's a fake).  Also be sure to buy the companion PC board to stabilize the pins on the pot, as you do not want to solder wires to them.

[A Jedi]

Thanks. What's difference between say the 50K and 250K versions in terms of volume? I wouldn't mind having a bit more knob travel to get up to volume. Currently I'm at full volume at like 10% volume. Would the 250K version make more sense for me?

[Paul Birkeland]

Thanks. What's difference between say the 50K and 250K versions in terms of volume?

There isn't one.  The 50K part will load down your sources more than the 250K part will.  With nothing plugged into the amp and the volume pot all the way up, the 250K part will let a little more ambient noise into the amplifier.  The 250K part will tend to give a little more treble rolloff as well compared to the 50K part.  100K is our preferred compromise value, but I wouldn't hesitate to use 50K too.

I wouldn't mind having a bit more knob travel to get up to volume. Currently I'm at full volume at like 10% volume. Would the 250K version make more sense for me?

This is covered in Crack FAQ #3:
https://forum.bottlehead.com/index.php?topic=4295.0
This has nothing to do with the impedance of the pot.

[A Jedi]

Thank you sir.

[Joe Garfield]

I bought the Alps pot. After mounting it and getting half way through wiring my amp I decided to wait and get the PCB breakout board for it. It's possible to direct-solder the pins on the RK27 pot, but every other connection in the amp is much more robust, so I felt like eliminating the weakest link was the obvious decision. Just sharing one person's perspective...

[Laudanum]

I soldered directly to the pins and it's been fine for 8 years.  I know it's not recommended but I've been pretty decent with a iron for a long time.   I finally bought a board about a year ago but I would have had to trim some wood away from the inside of the box in order for the board to clear.   I didn't feel like the extra work with everything working peachy as is so I went with the "if it ain't broke ... " approach and skipped it.   Maybe I'll eventually get around to it.  Or maybe someone makes a smaller board???

I'd definitely use the board if I had it before I changed the pot to the ALPS but I didn't even realize a mounting board existed back when I did it. 

[Natural Sound]

Also be sure to buy the companion PC board to stabilize the pins on the pot, as you do not want to solder wires to them.

I've used a piece of perf-board in the past and made my own stabilizer/strain relief. It worked pretty good.

[Joe Garfield]

There are a couple of different boards out there. Some of them have the holes for the wires below the pot, others have them to the sides of the pot. I wouldn't/won't use the board if I have to cut wood to make it fit.

[Markkr]

Can anyone point to a PCB available in the US? The only ones I see on eBay are overseas with a month long wait. Thanks.

[grufti]

Shipping info on international shipping is pretty much useless these days. I received two different shipments from mainland China in less than ten days recently with most of that time spent in the US between a west coast port and a west coast address. The auction site predicted about 45 days for those. I also received a shipment from Northern Italy about six weeks ago that took nearly six weeks to get here at an average speed of about 10 km/h. I would just roll the dice, if I were you.

[Deluk]

Cheap from China. Buy several. They might have an offer on multiple buys. Offer extras on this forum and make a few cents later.

[Paul Birkeland]

There are other nice pots with solder lugs that are available in the US if the wait time for the PC board is too long.

[jivex5k]

Yeah, the PCB from China stopped me from getting an alps. I ended up spending a bit more and grabbed an Audio Note pot that has lugs from here:
https://www.partsconnexion.com/ANVPOT-81914.html

You have to enlarge the hole for it slightly, I used a hand reamer, didn't take much. The stock knob should fit, might sit a bit high up though. I spent a little more to get a new knob from the same site. I was skeptical about spending around 80 bucks on a pot/knob combo but am happy with the result. I justified it by telling myself "at least I didn't get a TKD pot".

If you do grab the audio note, make sure it's for volume, a lot of people seem to mistakenly install the one for balance.

[Markkr]

Got it, thanks for the replies!