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On/Off Switch

People spend a lot of effort to feed their audio system with clean power. Dedicated power lines, new wires from the electrical panel, special hospital grade or audio grade power outlets, expensive devices to do additional power filtering are just some of the things that are quite often done in this hobby. Then we buy expensive power cords, special audiophile fuses, and even replace the factory IEC inlets with better quality.
This is all good, and I understand that once you have a system with high enough resolution, the changes are audible. But how often do we open the cover of our equipment to discover that although we spend so much money on a special power cord, the wire (incidentally much thinner and cheaper than our special power cord) from the IEC goes all the way from the back to the front just to go through a cheap on/off switch and back to the rear or the middle of the chassis.
I just looked at partsconnexion, hificollective, vhaudio, and a few other web sites that specialize in audiophile grade parts and could not find a nice solid audio grade on/off switch. Why is that? If a fuse makes a difference in the sound, and (according to some manufacturers) even the direction of the fuse has audible differences (something I can never hear btw), it would make sense that the contact parts of the on/off switch would be important too.
So my real question is does the quality of the on/off switch matter and what is a good on/off switch to use in a power amplifier?
nenon
pbnaudio's avatar
pbnaudio
1,614 posts
 
When you make Power amplifiers with extremely large power supplies the on/off function becomes an important issue, not only for being able to start the Amplifier but also for making the switching function last for a very long time.  

The on/off function in our Olympia power Amplifiers are made with a 40A Triac in series with 4 Inrush Current limiters in series parallel - once the initial inrush current is over  (which is VERY large when using a 4KVA transformer / 1 Farad  power supply)  2 each 20A relays with 2 contacts on each (theoretically capable of switching 80 Ampere) bypass the Triac/inrush limiter circuit.   To turn off the amplifier the low level signal to the relays coils are switched off.

This have proven a very reliable way to handle the on/off function. 

http://pbnaudio.com/audio-components/audio-amplifiers/olympia-ebsa-3

Good Listening

Peter 
ivan_nosnibor's avatar
ivan_nosnibor
1,055 posts
 
"Note. The power switch is a snap switch and should always be manually closed and opened in quick follow through movement. Especially on power amps. This will help in preventing of arcing when the switch is being opened. Arcing can/will cause pitting of the contact surfaces. Sufficient pitting will result in lower conductivity through the closed contacts. Enough pitting will cause a VD, voltage drop, to be created across the contacts of the switch. With VD, heat, followed by carbon, followed by more VD, more heat, arcing, and eventually the switch will fail."

Absofreakin'loutely. Great point about reliability.

"When you make Power amplifiers with extremely large power supplies the on/off function becomes an important issue, not only for being able to start the Amplifier but also for making the switching function last for a very long time."   

Agreed again, another great point: the more power, the more the concern about the power switch.

The power switch under normal circumstances is not necessarily the biggest concern in the power path, true, but if you're building and looking to upgrade the whole chain, then perhaps it should not be forgotten.

Regards to all, John
wspohn's avatar
wspohn
611 posts
 
Power conditioning?  Yeah it works (and has more effect with some components that others).

Power cords? Not so much

Power switches - not much effect at all so long as they make a good solid contact.

And I'd add to that, that they must be up to the job of switching whatever amperage goes through them.  I have one Class A power amp that has welded two switches closed so I just turn it on and off with a heavy duty power bar - I didn't want to start modifying the front plate to accommodate non-stock switches, nor to change circuitry to reduce turn on draw.
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