[Theo]

I've been listening to my Castanet built with all stock parts for nearly 6 months, and am getting a bid of an upgrade itch.  Am I correct to assume that the volume pot is the bottleneck on the Castanet.  Is anyone using a higher quality pot?  Any suggestions on what to buy?  What other upgrades should I be looking at?  Thanks.

[Bill Epstein]

I've changed the Alps Blue Velvet to the TKD pot in several components  as have friends. Much better sounding. From Michael Percy, $65.

Right now, tho', I'm using a PEC pot from Digikey $35 in a passive and it too, sounds great.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=KKA1041S28-ND


The Alps pot Radio Shack sells for $5 sounds better than the Blue which is used in tons of high end, high priced goods including KR, Audio Research, Ars Musica and many others. 

[Brinkman]

Goldpoint makes a great attenuator, though not as expensive your average DACT pot, it still costs a bit more than the others mentioned. There's a remote control kit that it's compatible with, and I will use the pair in my completed Clarinet line stage. Not that you'd need a remote for a headphone amp...

-Brinkman

[Theo]

Thanks guys.  That narrowed it down quite a lot for me.

[dnewman]

I've been listening to my Castanet built with all stock parts for nearly 6 months, and am getting a bid of an upgrade itch.  Am I correct to assume that the volume pot is the bottleneck on the Castanet.  Is anyone using a higher quality pot?  Any suggestions on what to buy?  What other upgrades should I be looking at?  Thanks.

In two of my three Castanets, I upgraded the pots to Goldpoint attenuators.  In the
process of doing so, I was not at all surprised to find that I had to bring the attenuator
well forward in order to avoid picking up some low frequency EMF noise.

Specifically, the Castanet is an amazingly compact package considering all the iron
in it as well as a tube.  (Tubes can spray noise around too.)  I'm still somewhat
amazed that Jim got it as compact as he did AND kept the noise floor down at
the same time.  So, when I was going to replace that little 1/4 to 3/8 inch deep
pot with something approaching 1 and 3/4 inches deep, I was concerned.  And,
sure enough, when I first tried it using the "stock" enclosure, I found I was getting
some annoying noise.   I then tried some shielding but that didn't work to my
satisfaction.  What did help was to bring the attenuator forward.  Even then it
still wasn't as quiet as with the pot.  Possibly because the attenuator still entailed
wires which were out of the plane of the PCB.  Shielding those wires (with a drain,
of course) seemed to resolve the issue -- to my ears at least.

I'm not 100% convinced I made an improvement -- at least not one worth the added
cost and effort.   And, when it comes to cans over my ears, there's something to be
said for continuous variability in volume adjustment.  So, I cannot recommend
replacing the pot with an attenuator unless you just want to tinker.

BTW, I had a similar experience attempting to use some different headphone
jacks on the Castanet.

All in all, it's a wonderful headphone amp.   However, its compact layout means that
you need to be extra careful in your modifications.  And you certainly need to first
build the unit unmodified so as to have a baseline for comparison.

As an aside, I really like Goldpoint attenuators.  And, every time I buy another unit
from Arn, I am amazed to see that he has implemented yet another beneficial refinement.
(I have no affiliation with Goldpoint nor Arn Roatcap; I'm just a very satisfied customer.)

Dan

[Theo]

Thanks Dan.  That's good advice.  I wanted to tinker but I don't want to open a can of worms.  May be I'll just upgrade the caps and try a better tube.