Part Sourcing Assistance/Advice Thread

[Mister X]

I don't know, do they? Does Mouser?

 

 

# 534-1705

 

http://www.mouser.com/catalog/catalogusd/647/2161.pdf

[dsavitsk]

 

Does McMaster-Carr stock something like this panel bushing for 1/4" shafts

 

http://www.abbatron.com/advanced_search_result.php?keywords=119&osCsid=11d56dd2c9392cf240348216c5dfa10a&x=3&y=5

 

 

Strong recommendation to make a bushing from Delron instead of steel or aluminum. Or at least use a Delron rod.

 

http://www.mcmaster.com/#standard-acetal-homopolymer-rods

[chiguy]

What are the advantages of Delron over steel or aluminum?

[Mister X]

lower friction and electrical isolation.

[muskyhuntr]

I have used Delrin rods on 2 different builds and have been very happy with the results.  Electrical isolation is my main reason for use but cost and easier machining also weigh in.

 

Me

[PICaudio]

Delrin is a very good choice for this use, other option could be the iglidur bushings

 

 

And if you want a option without electrical isolation, I think the Selfoil bushings (or any sintered bronze) are a good choice because are self lubricating.

 

[sbelyo]

# 534-1705

 

http://www.mouser.com/catalog/catalogusd/647/2161.pdf

Bingo, thats the one

[sbelyo]

I have used Delrin rods on 2 different builds and have been very happy with the results.  Electrical isolation is my main reason for use but cost and easier machining also weigh in.

 

Me

Does it slip when you turn it?  I'm using it to turn the shaft of a volume control and goldpoint switch.  The knob will be collet mount and the shaft coupler is a clamping style

[luvdunhill]

The negative of Delrin is torsional strength.

[muskyhuntr]

If what you mean by 'slipping' is a feeling of flex in the rods while turning, it depends.  On both a M3 build and an Aikido (picture below) there is no feel of flex when turning normally.  However, when going past the limits of the switches/volume control you can feel some flex.   The M3 has less flex than the Aikido due to it having shorter shafting, but not by much. I plan on using the same shafting when I finish casing my KSA4.

 

Me

 

[PretentiousFood]

On the topic of potentiometers: does anyone know where to get a decent audio taper one with a 25mm/1" shaft? I'm restoring a McIntosh unit with two mono Alps pots and the original part was discontinued. I tried replacing the original pot's deck, but that didn't go so well. Flatted/D would be ideal but I can always file a round shaft down. Best bet so far is probably to just use one of two decks on a stereo rk27.

[n_maher]

I'd have a look at percy audio as a start.

[PretentiousFood]

Looks like the Black Beauty might fit! Thanks for the tip, I hadn't heard of them before.

[Pars]

They also have the TKD mono CP2500 pots as well. The Alps are only available in a 250K which seems pretty high in value.

[nopants]

They also have the balanced TKD's which I'm mighty interested in. Now where to ditch the 601S's

[PretentiousFood]

Shoot, hadn't noticed they were 250k. They're a bit bigger than I can comfortably cram into the chassis anyway. The TKD stepped attenuators would work, but each one costs more than my friend paid for the amp. The potentiomters aren't long enough unless he has a special production. 

[luvdunhill]

Any recommendations on a very compact 47uF/400v (-ish) film capacitor? Smaller the better.

[luvdunhill]

The new Wima DCP4 seems to be quite impressive and fit the bill. Anyone tried these?

[PretentiousFood]

I haven't tried the Wima, but I've had good luck with the new Panasonic EZP in power supplies. A bit bigger but cheaper, also stacked PP. The Vishay DC-Link stuff is a good bet too.

[nopants]

have you ab-ed the film caps in psu use against standard electrolytics? it sounds inviting from a longevity perspective but I'm curious how the parasitics end up changing the sound, if at all

[PretentiousFood]

I've tried but I think I have tin ears. There really isn't a good way to quickly swap out a high voltage supply without building some complicated rig, and the amps where I've tried it already had high supply rejection. I've always justified it to myself based on longevity and an aversion to series connected caps, for a relatively small increase in price now that everyone's releasing big DC link caps.

 

E: I think Frank Cooter has a few posts about switching to film caps for B+ to good effect in his single-feed designs.

Edited November 29, 2014 by PretentiousFood

[luvdunhill]

I suppose I could do some comparisons...

 

[dsavitsk]

I recently did some comparisons of PS caps on the output of a regulator in a differential tube amp. Just by ear, I thought the DC links (not sure which brand I used) worked about as well as the ASC motor runs, some Mundorf M-Tube caps, and a bunch of other expensive film caps. They were better than electrolytics, but decidedly worse than the Multicap RTX which were by far the best option I tried.

[luvdunhill]

The largest the RTX come in is 1uF/400v and are fairly big at this size, so unfortunately are a no go for my project. The advantages of DC Link is the size and footprint, so perhaps a bit of an unfair comparison.

Edited December 5, 2014 by luvdunhill

[luvdunhill]

Pretty bummed as I just got in some parts and realized that instead of ordering 6 noval tube sockets I ordered 7 pin sockets this was a while ago (CMC ceramic) so can't return them. Anyone need a bunch of 7-pin sockets? I can do sub-China prices