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Better than Elma switches?

Mike P

Trade: Pickwell Audio
I have a Music First Audio TVC, which sonically I love but the 2 pole 24 step switch that controls the volume has become noisy and unreliable. On some of the most used positions I'm getting the occasional channel dropout and problems with a shifting stereo balance.

I've tried cleaning the switch multiple times with a stray of Servisol Super 10 but I think the time has come for more drastic action, which is something I've been putting off because the complexity of the wiring and soldering that's going to be needed. This very disappointing for such an expensive switch in such an expensive pre amp.

An engineer friend who's opinion I trust told me:

"I have bad experiences with Elma switches. After just under two years, they start to scratch. Ok, they may be cleaned once in a while, but it is a problem to align the levels exactly again afterwards in order to have an even contact resistance over the entire surface. The slider, which works by means of spring pressure, is usually worn out by then. A small sheet metal part. I have written to the Elma sales department several times asking them to send me the slider and springs as spare parts. They have no intention of supplying this wearing part!"


So I'm reluctant to go to all the effort of removing the switch and stripping it all down for a thorough clean if it isn't going to do the trick and I'm also a bit reluctant to buy an another expensive Elma if I'm going to be facing the same problems again in a few years.

I'm interested to hear other peoples experience with high quality switches. What do you have and how reliable has it been?
 
People say good things about Sieden but I have no personal experience of them. Not cheap though.
 
That is disappointing.

I’ve been running 1990s vintage Audio Synthesis Passion series stepped attenuators (I have two) for years and the attenuators they used are still going strong. Looking on HiFiCollective they are most similar design-wise to Seiden or TKD.

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This design is so simple and mechanical I’d expect it to be possible to resurface or re-create the wiper if need-be. If there is room in the Music First box I’d look at this basic idea anyway.
 
I have built two stereo switched attenuators from the Chinese 2 pole 24 position switches. Must admit that they aren't used every day, but have been reliable up until now. The one in my B4 buffer gets more use and has seen 2 years useage. No drop outs or nasties...yet.
 
I've used Elma switches (metal body versions) numerous times in DIY projects and never had a problem with them .
 
Elma switches were used on the (circa 1972) BBC tape machine control panels,(4 per) I would have expected them to have changed supplier if they had been troublesome.

Perhaps modern ones are not so good.
 
This afternoon I managed to partially disassemble the switch for better cleaning access whilst leaving all of the wire connections in place.

So far it seems OK and fingers crossed that's done the trick.

The preamp isn't in a vented case, so it's hard to see how the switch would've got dirty in the first place. It was a second hand unit purchased from Emporium HiFi and I don't know the history of it.
 
Well what a difference!

The stereo image has snapped back and is rock solid. My system has been sounding a bit 'off' for a while but is now back to firing on all cylinders.
 
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Grayhill make some nice ones, and they are small enough to fit in tight spots. Not sure if they have 24pole ones mind you!
 


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