Hello,
i have "audiophile" hifi system, even components are old the rpp is around 8000 euro.

The amp has manual power on/off switch / same for DAC and these are two components that i want to control via smart home.

For that purpose i want to create custom module that will be installed between 230V power socket and SUPRA MD06-EU MKIII mains.
The intent is to use Omron relay https://eu.mouser.com/new/omron-electronics/Omron-Relays to control Phase/Neutral/Ground (3 separate circuits) or only Phase (?)
The relays will be somehow controlled by some esp32 module (smart home).

The end2end scenario is that
- amp switch is power on permanently (musical fidelity nu vista m3)
- DAC switch is power on permanently (burson audio)
- custom made module will control relays and Power on/off whole system via esp32 automation

Is that doable or does it make a sense?


Thanks

 

Personally, I don't like switching the AC mains on things like audio equipment. Modern electronics have slow idle power and cold 'iron' power switching stresses components. The fancy power strip won't help with that.

 

There's too much we don't know about the components. High-end audio manufacturers tend to do some goofy stuff to make their equipment "different" -- different and goofy enough that I probably wouldn't power them up in any way other than what was intended, without a thorough knowledge of the circuitry.

And I certainly wouldn't want to be responsible for telling someone else that an idea like this would work, and have them burn up an expensive unit due to some unknown oddity.

 

My home theater components apparently talk to each other over HDMI and so changing the power status of one of them triggers the rest. I love this feature in large part because I didn't have to do anything to make it happen. It just works right out of the box. I can turn the entire system on or off using any one of the handful of remotes.

My point is that it's possible this sort of feature is already built into your equipment. I know my older amp had some sort of 12V control scheme. So instead of switching AC power to expensive components, maybe you could switch power to something cheap (like an old AppleTV) and have THAT device send the signal to the other devices to wake them up.

 

@nsaspook
this are not modern in terms of cheap electronic devices. They have proper manual switches for power on/off
@wayneh
musical fidelity nu vista m3
burson audio conductor

No hdmi etc... each has its proper manual power switch

The end2end scenario is that
- amp switch is power on permanently (musical fidelity nu vista m3)
- DAC switch is power on permanently (burson audio)
- custom made module will control relays and Power on/off whole system via esp32 automation



Is there any difference if someone push manual switch comparing switch is on constantly and you control input 230V circuit of the mains?

thanks

 

Your power amplifier probably includes an oversized toroidal transformer. It is likely to take a big inrush current when switched on. This is made worse if it is being switched by a triac synchronised to mains zero crossing. For the toroid and associated smoothing capacitor, the big inrush current is “all in a day’s work” and it hardly minds at all. Whatever is switching it might not appreciate that big inrush current and may blow fuses, or triacs.

 

@Ian0 i think 3 toroidal - one for preamp and then then 2x each per channel and yes these are big - its separate box for transformers/psu - where is power switch on/off.

but is there difference if you manually press the button on PSU versus you cut on/off phase on the mains?

 

@Ian0 i think 3 toroidal - one for preamp and then then 2x each per channel and yes these are big - its separate box for transformers/psu - where is power switch on/off.

but is there difference if you manually press the button on PSU versus you cut on/off phase on the mains?

Maybe.
A manual switch and a relay behave very much the same. The phase angle at switching is random, and it is accompanied by contact bounce.
It is different if it is switched with a triac. It could be randomly fired, in which case it is similar to the switch but without the bounce, or it could be synchronised with mains zero-crossing, in which case you will hit the transformer surge every time (but never the capacitor surge).
It is the switching device that will suffer the most.

 

@Ian0
does it mean that maybe my amp and DAC are both powering on via switch with a triac? so in case i analyse that and there is no triac (both amp, dac) it doesnt matter if i built a relay module or power on manually?

Thanks

 

@Ian0
does it mean that maybe my amp and DAC are both powering on via switch with a triac? so in case i analyse that and there is no triac (both amp, dac) it doesnt matter if i built a relay module or power on manually?

Thanks

Unlikely to be a triac inside the amplifier, but many “home automation” products do use them to switch outputs.
If you use a relay, it will be no different from using the switch. Makes sure that your relay is adequately rated, and never switch the earth conductor.
Switching both poles (live and neutral) is good, especially if you live in a country with reversible mains connectors, but a double pole relay will only handle half the current of a similarly sized single pole. Double pole switching is also good for eliminating arcing - you effectively get two switches in series, and double the contact gap.
I wouldn‘t entertain using anything less than a 16A relay.

 

If the switch is simply in series with the mains, it doesn't seem there could be much risk in simple switching the mains. If the switch has any other connections, or is connected to something other than the mains, I would be circumspect in using mains switching as the method.

 

Okay I will try to find out from the manufacturers

how the switches are implemented in the device and let you know. But both devices are 10-20y old ... so i assume simply in series with mains.

 

https://www.netio-products.com/en/node/1069

so the best way is Zero Current Switching?

 

We call it zero crossing switch.
You can buy zero crossing SSR (solid state relay) for controlling AC devices.

 

but who / how decide if there is zero current? some electronic in the relay?

thanks

 

@MrChips
but zero crossing SSR - A zero-crossing Solid State Relay (SSR) is a type of SSR that switches on when the AC load voltage is near zero.

So its not switching when current is zero?

 

It detects AC voltage and turns triac on/off at zero voltage.
If the load is disconnected, there is no current to measure.

https://www.omchsmps.com/zero-crossing-solid-state-relay/

 

https://www.netio-products.com/en/node/1069

so the best way is Zero Current Switching?

Not when you have a big transformer.
The transformer starts off with flux=0, but when voltage is zero, flux should be at a maximum, because V=dΦ/dt.
The result is that half a cycle later the flux is double what is should be and saturates, losing all its inductance and taking a current equal to the voltage divided by the DC resistance of the transformer.
Switching at mains zero crossing is the worst way of switching a big transformer, and the best way of blowing a fuse.

Logically, zero current switching makes no sense whatsoever when you are switching something ON, as of course the current is at zero because it was previously switched OFF.

 

So in that case, does zero-current switching make any sense?

In case i have to build module using zero crossing SSR (solid state relay) ... could you advise on it a bit more? ie design part.

Thanks!

 

I did add a SSR and mains filter to my (120V) stereo power system. That then feeds a couple power strips, so I have switched and unswitched power outlets.
My main big amplifier is home made 1,500VA power transformer E-core and plenty of inrush.

The SSR was from my junkbox IDEC RSSDN-25 (660VAC 25A continuous, 75A 1-sec, 300A 1-cycle, zero-cross). It is rated for 1kVA 120V/2kVA 240V transformers based on 1/2 cycle inrush, in their datasheet.
Sometime the mains wiring in the wall will rattle on turn-on. I think it depends on the residual magentism in the transformer's core.

Mains -> Circuit breaker 15A -> TMOV -> EMI filter -> SSR+power strip AND power strip.
Power for the SSR input 4-32VDC is from a tiny power transformer and rectifier, always on.
Next I was going to add remote control, ESP-32 to control the SSR.
I might add a gas tube pair to protect against bad transients.
edit: this is all in a metal enclosure

Although I've read and seen the results with SSR's best switching inductive loads at lowest dV/dt, you need a "random phase" SSR and then switch it only at AC peak, opposite for turn on and off no net flux accumulation, etc. I am lazy and this is too much hassle. So I just live with the occasional high inrush event.