Solid State Relay for an amplifier mains power switch

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#82
IanAS said:
Jan, that's rather like saying that all matter is standing waves and we're living on an atom in someone else' nuclear explosion so we cant know anything except that we know we can't know anything.

I might be able to, not going to, count up 40 people of various walks of life, education, employment, IQ, musicians and tone deaf, who have hi-fi and who have independently swapped many parts, very large and very small, of their hi-fi and discerned a difference, a preference, and evolved and refined their systems sound and gain more pleasure from it.

They didn't need a doctoral research panel of experts working for months to tell them anything. Their own ears and brain were enough.

I know a few people who's ears and brain were not enough, spent very many £thousands and have never been happy with their sound, no matter what they changed, sounded bad to everyone else too.
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OK, I get it, you're comfortable in your own private reality, not interested at all to learn what's really going on. Fair enough.

Jan
 
#86
IanAS said:
Thanks for making the effort. 🙂 I think it's fair to assume that your test equipment is not as good as the human ears and brain at detecting the sonic changes in complex music signal emitting from the speakers during music play.I don't have any here now. And I don't need or want to. My question is very specific. I don't need anyone attempting to prove that we all can't hear what we so obviously can.
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Blah blah blah. Useless opinions. I think its fair to assume your wrong. My saying you can't hear **** has as much value as you saying you can.
 
#90
jean-paul said:
Surprisingly no one mentions that zero crossing SSRs are a bad combination with transformers.
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Why is that Sir? You could accidentaly switch on and off around zero crossing yourself...What would be that bad thing that happens? You can have it in the primary as a power switch or 4 of them in the secondary as active rectifiers and I saw people here swearing on their qualities...Not a fan myself of active rectifiers in low power audio applications but anyway... I used them in series with capacitors a lot for starting high power motors which are highly inductive taking 6 times more current before they idle.I mean they were passing tens of kilowatts...why wouldn't they be able to deal with a home amplifier found in the range under 300 watts of power ?
 
#91
Accidental is something else than repetitive. Yes it is (about the worst possible way of switching power to transformers) but since you know better I leave it at that.

I was clearly referring to zero crossing SSRs and power transformers like the thread title indicates: "Solid State Relay for an amplifier mains power switch".
 
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#94
To switch inductive loads off, the zero-crossing detector needs to operate on current, not voltage. Zero current of an (quasi-)unloaded transformer (=inductor) happens at/near max voltage. If you switch off at zero voltage (=max current) this causes a massive amount of back-EMF producing very high spike voltages, stressing/killing the switch.
 
#96
KSTR said:
To switch inductive loads off, the zero-crossing detector needs to operate on current, not voltage. Zero current of an (quasi-)unloaded transformer (=inductor) happens at/near max voltage. If you switch off at zero voltage (=max current) this causes a massive amount of back-EMF producing very high spike voltages, stressing/killing the switch.
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And very high currents. Absolute worst way to switch power transformers with nasty side effects. Much more stress for both transformer and SSR.

This keeps coming back as it is one of the misunderstood items in electronics. It would work OK when a resistive load would be switched (as probably assumed).
 
#97
KSTR said:
To switch inductive loads off, the zero-crossing detector needs to operate on current, not voltage. Zero current of an (quasi-)unloaded transformer (=inductor) happens at/near max voltage. If you switch off at zero voltage (=max current) this causes a massive amount of back-EMF producing very high spike voltages, stressing/killing the switch.
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Get the point. But the SSR with zero crossing are designed to work with inductive loads. They turn on at zero crossing voltage and turn off at zero crossing current.

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#98
IanAS said:
The best by very far that the test system sounded was to solder a 25mm² 'super spur' direct to the amplifier transformer with no plugs, switches, fuses, tracks, anything, other than an appropriate fuse at the meter board after the distribution block in it's single carrier, that also acted as the switch by simply pulling it out of it's carrier. Neutral with no switch, just going into the distribution block. The installation being compliant with the UK 16th edition regulations.

Obviously that's not a practical way to operate a domestic hi-fi, so I made and inserted various switches at the amplifier between the spur and the transformer, all had a very disappointing and damaging effects on the tonal balance and realism of the sound quality.

I've not yet tried sold state relays.

The high repetitive current ones are expensive and I don't want to waste a further load of money if the tests have already been done and the results were not any good.
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Well, I suggest you try to keep things as simple as possible by trying to figure out why your best test system sounds better than another simple alternative such as standard mains cable and socket. Make lots of measurements, do some detailed analysis. Boil things down to their essense.

If you add a SSR into the equation you are adding a lot of unknown variables and complicating the situation even more. You're unlikely to find the true reason behind the sound differences you say you can hear taking this route.
 
#99
Baffless said:
Get the point. But the SSR with zero crossing are designed to work with inductive loads. They turn on at zero crossing voltage and turn off at zero crossing current.

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I checked a few products and datasheets and it seems like indeed most SSR's qualified as zero-crossing switching do switch on at zero voltage and switch off at zero current, but not all do.

We still have the problem of an upstream interruption which might generate large kick-back voltage spikes (but at least this will never happen on a regular everyday basis).
Therefore, using snubbers and transient supressors appears to be mandatory to keep the SSR happy, even if proper zero-crossing type. Usually, these components are already integrated into the SSR, but we better check for this.
 
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