I replaced the volume pot on my tube preamplifier.

I was going by the label on top that shows 50KA X 2

@mashif

That’s a specification - 50,000 ohm input impedance, x2 for stereo (2 gang) - not a model number. If you were looking at an RK50 model you’d think "wow!" - it’s massive, shiny, beautiful and gold :) 

The RK50 doesn’t imply 50,000 ohms either (though that is a very common choice); it comes in a few different impedance values. 

Yeah, it's a $16 pot available everywhere, probably on par with the 27. But the RK50 is about 100x the price, $1500 or so. So there's another reason for an upgrade. Oh well. 

@noromance Thanks for posting about this! I built a Waynes 2018 preamp, a DIY design from the good folks at Pass labs that I put an Alps 27K in and it is good. But you and the other contributors here have given great leads on what promises to be a significant upgrade. Thanks too to @mulveling. I don't think I can swing the RK50 but the Alps RK40 looks doable! Great stuff.

OP has touched on a very overlooked part of preamps.  An afterthought piece which is quite critical to everything.  You guys are technically beyond me, but I can hang with the best when hearing the differences in quality.

There are some volume pot geeks who've drilled deep into the subject.  Thanks for the posting.

I wouldn't say the standard RK27 is complete junk. But it's a $20 (retail) wiper that is inside of a lot of good sounding equipment. It does absolutely amaze me that a builder will put together a $5k plus piece of gear & stick a Blue Velvet in it. Stick a bunch of pricey boutique capacitors, resistors, & overpriced rca jacks in a preamp then skimp on the volume control.

I think the consumer would gladly pay a little extra for a volume control that can really take the overall performance to the next level. 

The main problem with switching out a pot is that there is rarely any room to make the change. It can be a major pain in the butt & an easy way to add noise if not grounded correctly. You gotta get creative. I just replaced a RK27 in a tube preamp with a Goldpoint SMD attenuator. Better clarity, separation, & depth of stage vs the Velvet. And the GP is just a regular stepped attenuator. I  have a couple of Nobles from the 90's that still work well.