[roymail]

I've always wondered just why designers put the power switch on the rear of so many amps and preamps.  It seems inconvenient, yet some put them on the front panel.

What am I missing?  Any logic to it?  Thanks!

[mcgsxr]

I think it likely is due to many folks leaving their gear on all the time.

There is some gear I leave on 24/7 (pro amp that runs my HT sub - the sub is on the main floor, the amp is on a shelf in the basement), but most gets turned off.

Could also be that the remote has a stand by button?

[Abby356]

After having just built my first DIY First Watt amp I would have to guess that it has to do with the physical distance between the AC IEC inlet -fuse block- on/off switch and the opportunity to introduce noise into the system. With the switch on the front of the amp like my chassis was set-up for i had to run 14" or so of wire to the front panel switch then 14" back to the power supply. If the power switch was on the rear it would have been more like 6" total instead of 28". Just my 2 cents...

Regards, Daniel.

[Wayner]

I believe some manufacturers of hi-end amps put their switches on the rear for 2 reasons. First, for appearance. Second, most folks like to run some type of AC line suppressor/conditioner and those units usually have a second power cord that plugs into the preamp for sequential amplifier turn-on/turn-off. It is generally of no advantage to leaving equipment on 24/7 unless you want them to burn out prematurely.

Of course, never plug a high power amp into the back of any preamp's switched outlets, as the inrush current is very high and will destroy the usually smallish power switch of the preamp.

Regards,

Wayner

[jules]

I agree with Wayner and Daniel and I've placed the switch on the back of a couple of designs I've built after weighing up the possibilities.

A couple of other reasons:

 * Switches, particularly those that carry medium-large current, can burn out after a long period of use. If you use a common, standard, easy-to-obtain-forever type switch you do not get caught out in a few years time by a part that is no longer available [don't laugh, I got rid of an otherwise good amp that suffered from this impairment]

 * Wayner mentions "sequential amplifier turn on/off". Switches on the back of equipment prevent curious fingers from testing to see what might happen "if I flick this switch". There are switching combinations like turning off a source while everything else is running that can cause dangerous speaker popping in some systems [and a fuse might not be enough protection].

jules

[Glen B]

All of the equipment I have owned with a power switch on the rear, was meant to be left on 24/7.  Any front panel "on/off" switch was just to put the component in/out of standby or mute/unmute its output.

Switches on the back of equipment prevent curious fingers from testing to see what might happen "if I flick this switch".

Funny you should mention curious fingers.  When my young grandson was 2 years old, he discovered the toggle style breaker on back of my balanced power conditioner.  Sometimes I would get home from work and find the power turned off.  A $2.00 plastic toggle guard solved that problem.

[Wayner]

All of the equipment I have owned with a power switch on the rear, was meant to be left on 24/7.  Any front panel "on/off" switch was just to put the component in/out of standby or mute/unmute its output.

I hate to disagree with you, but I do. No equipment needs to be on for 24/7. That is just incredible waste of energy, and is really hard on the equipment. Why make it wear out needlessly, caps will change, resistors will fail, all for a myth. However, I do respect your right to do as you see fit, it's your equipment and your electric bill.

Wayner 

[Glen B]

What are you disagreeing about ?  The topic was about why manufacturers put power switches on the rear, not about whether it is a waste of electricity.  I was only giving an opinion on why this was the case, based on the manufacturer philosophy and recommendations.  Don't kill the messenger, take your argument to the manufacturers.

[Wayner]

Well, that is not the reason manufacturers put switches on the back. My Outlaw RR2150 has a switch on the front and a switch on the back. Even small current draws add up to to lots of $$$ over the long haul.

By the way, I've spent several decades in the lighting industry, and CFLs are a rather large joke on the public at large. Sure they consume less power, but then they also put out less light. You pay a premium for the lamp, and if installed base up, will fail sooner then base down. They are also full of Mercury and other heavy metals and are an environmental hazard. A great energy conserving measure is to do lighting by design, with three stages of lighting: cleaning (all on full power), twinkle (to give some effect) and task specific. I also am a large supporter of dimmers, with todays Triacs (insted of the old fashioned rheostat) put the user in control of light effect and lighting costs.

Wayner

[Glen B]

Your RR2150 has a power switch on the rear, do you turn it off when you're not using the receiver ?  If not, and you use the front panel switch or remote, then you're wasting power.  If you use any other equipment that is remote controlled, has soft-touch power buttons, or use wall wart power supplies, then you're also wasting power.  These devices all draw some power, even when "off".  Unless you can answer no in every case, then you're also using small amounts of power that add up.

[Wayner]

It's off right now, as I seldom use it. How much current do you think your equipment draws that are on 24/7? I didn't mean to get this thread off topic, or turn it into an energy consumption debate.

I have a Sunfire II amplifier that has no switch at all. Did Bob intend for me to leave the amp on all the time? I doubt that. Bob was smart enough to let some other switch be the "sacrificial lamb", as he knew the tremendous inrush current would likely kill any power switch (unless it was industrial strength) so he left it out completely. That was an economical and warranty decision.

Power switches were the demise of many a fine audio amplifiers, because the designer, didn't understand the inrush current scenario, which can be tremendous.

Here is a little know fact. Your typical 120 volt outlet can deliver 50,000 amps to kill your body very, very dead in quite the very short order. How is this possible? Dead shorts will deliver all the goods until there is component failure, like copper wire or outlets or the circuit breaker (which is not instantaneous). It really only takes 8 milliamps to stop the heart muscle, so imagine what 50,000 amps can do.

Back to the switch element, switches are the "sacrificial lamb", because they break the circuit under a load. When this is done, the switch slowly starts to decay, by the shear destructive power of the "break" arcs that occur inside of the switch body. Do you ever see a spark under the ivory switch plate of your house switches? If you see spark, there is destruction.

I'll conclude, by saying that switch placement is more political then anything. The reasons are many, but the most influential is cost. Period.

Have a good one Glen.

Wayner 

[roymail]

If fused properly, will that save the amp?

[Wayner]

No.

[K Shep]

take your argument to the manufacturers.

He is the manufacturer.

[Johnny2Bad]

I have a preamp with the power switch on the side, as compared to the rear or front.
I like it. It's convenient enough to operate and in this particular design, it's on the side where the PS lies and doesn't require a long run of wiring internally. Personally, I would like to see more of that style on gear.