[morsel]

I would like to hear comparisons of stepped attenuator rotary switch mechanisms, specifically with regards to the feel, how easily and quietly they rotate, whether they generate any electrical noise, mechanical noise, are they make before break, etc. These are the rotary switch mechanism and stepped attenuator makers I know of:

Elma used by Elma, DACT, Goldpoint, HeadRoom






Grayhill used by Octave, DIYzone

TKD

fake alps

The fake Alps is dreadful. Ridiculously high rotational force is required. It is both mechanically and electrically noisy with break before make contacts.


Shallco

Electroswitch

(too many styles to show)

 

[timoteus]

I am using a Seiden make before break switch on my current project. The "feel" of this switch is nothing short of amazing. When you add a very heavy stainless steel Dact knob the feel becomes even better. I wish I had this switch on every piece of equipment I own.

John Chapman of Bent Audio carries this Japanese switch for US $150 but is going to discontinue it because the exchange rate is going to drive the price to $200. He will carry the Shallco instead which he considers to be of equal quality. He has said that the detents on the Shallco have an industrial feel to them which he is working on modifying.

The only two switches I have compared directly are the Seiden and Dact. The Seiden has a silky smooth soft detent with just the right amount of resistance. The Dact has a hard edge click to it and feels a little sloppy in comparison. This of course has nothing to do with the quality or sonics of the switch. I'm just commenting on their tactile qualities. Hope this helps a little.

Edit: You can read more about the Seiden switches here.
http://bentaudio.com/parts/diy.html

 

[ITZBITZ]

I used the Elma switch.

The action is very smooth and voodoo who's finished his says there is no contact bounce. It's a make-break switch, so it seems it should be quiet. Also, the ladder switch is pretty easy to solder up, although I'm only have done with mine (after 3 hours of cutting, forming and soldering).

The turning force is smooth, but has solid thunks between steps. I laid out a custom taper to make sure I had enough divisions in the area of volume I listen to the most. I think I posted that spreadsheet in the thread about the elma 5 wafer switch.

 

[Voodoochile]

I like the Elma a lot. It's not only the make-before-break, but it is also fitted with different contacts designed specifically for zero bounce, even if turned quickly. Very resonable turning torque, and it's a rugged assembly.

I also have a pair of the fake alps attens, and they do suck indeed! I had one in a plastic box with pigtail leads for bench testing boards (because it sucked too much to be part of an amp), and it's too noisy and frustrating to use for that, even.
If it was free, it would still be overpriced.

I don't own, but have tried the Shallco 45-position switch-based series attenuator, and it is very nice. But the thing is pretty big, and they don't seem to readily have a switch with enough decks to easily make a ladder. You could do it, but the diameter would be *huge*. But the switch is wonderful. The torque required is a bit greater than the Elma, as you might expect, but still reasonable. A chassis big enough to hold the Shallco would easily allow the use of a 1.75" or larger knob without looking goofy. That makes a good difference in the feel.

A pic of the Elma 5-deck ladder switch, built with Holcos:

 

[morsel]

Can anyone comment on Grayhill .vs. Elma?

In another thread I used Babelfish to translate a German pot site. There is some fascinating detail on a TKD CP2500 pot describing the laser trimmed multisegment resistive element. They suggest it is so good they no longer use Elma stepped attenuators. Note the separate parallel trimming elements that tie in to the main element at each logarithmic junction. This is a pot constructed like a stepped attenuator. Has anyone tried these?

 

[hadron]

Haven't tried the TKD pot, but the 2P-65CSxx 40 step attenuator is very nice. Just the right amount of torque needed and a good detent feel, though a bit loud since it uses a spring-loaded ball and a notched disk.

 

[JohnFerrier]

Hmm.

 

[fyleow]

Morsel what about the Alps Black Beauty? It's still available from some places I think, I used one and got it from Percy when I built my Gilmore. It did not have the same problems as the fake blue alps you mentioned, but when I checked it with my Fluke I was not impressed by the resistance matching of the two channels.

 

[morsel]

I should know better than to derail my own threads.

I'm still hoping for feedback on the Grayhill mechanism.
Great pix, everyone, thanks for posting!

 

[fiddler]

I wonder which one out of these has the best price/performance ratio? When I get the funds, I'm planning to build a PPA... probably first with an Alps Blue but I'm leaving it off the board for an easy upgrade to a nice stepper. Or I'll just build the stepper from the start if it's affordable enough.

 

[Voodoochile]

Quote:

Originally posted by fyleow Morsel what about the Alps Black Beauty? It's still available from some places I think, I used one and got it from Percy when I built my Gilmore. It did not have the same problems as the fake blue alps you mentioned, but when I checked it with my Fluke I was not impressed by the resistance matching of the two channels.

I believe those are detented volume pots. I have one from Mike and that is exactly what it is. It's a nice pot than the Blue, but not by much. Just has that clicky feel to it, which I find odd. You get the disadvantage of steps, but not the advantage of a cleaner signal path.

I think Mike says that some are detented and some are not. Can't have a stepped attenuator without detents.

 

[Pars]

Quote:

Originally posted by morsel Can anyone comment on Grayhill .vs. Elma? In another thread I used Babelfish to translate a German pot site. There is some fascinating detail on a TKD CP2500 pot describing the laser trimmed multisegment resistive element. They suggest it is so good they no longer use Elma stepped attenuators. Note the separate parallel trimming elements that tie in to the main element at each logarithmic junction. This is a pot constructed like a stepped attenuator. Has anyone tried these?

Morsel,

I have one of these CP2511s in my Counterpoint preamp, and it is very nice, response and action-wise. Mike Elliot (of Counterpoint, now Alta Vista Audio) uses these in his Counterpoint rebuilds (www.altavistaaudio.com). Note that TKD also makes an actual stepped attenuator... Michael Percy carries it.

Chris

 

[00940]

Quote:

Originally posted by morsel I'm still hoping for feedback on the Grayhill mechanism.

iirc,, Antness has been using it in his last amps. Recent customers could inform you.

btw, it's also used in the pathos amps : http://www.pathosacoustics.com/indexeng.htm

 

[morsel]

Grayhill comments, anyone?

 

[doobooloo]

Where can I get these Grayhill rotary switches, not as a complete/kit stepped attenuator but just the switch alone?

Also, usually - how is the resistor matching in preassembled/kit stepped attenuators? Even in worst case, is it anything to worry about?