Home Theater Forum and Systems banner

1 - 20 of 34 Posts

·
Registered
Joined
·
32 Posts
Discussion Starter #1
sorry if this has been asked before, i've searched but have come up empty... are you guys aware of any of the pro amps that feature an auto on function? seems like a trivial feature, but it is rather necessary in an installation i'm considering.

thanks for any suggestions,
scott
 

·
Premium Member
Joined
·
15,054 Posts
I cant think of any but there are other options. One of the best is getting one of these Ethereal power conditioners that have a built in trigger for several of the outlets.
 

·
Registered
Joined
·
65 Posts
I can't think of one. But do you have a power center of some sort. I have mine plugged in to a switch outlet on the power center and it works great. I hit one button and everything except the blu ray. Xbox. Dish etc. Then you just turn the one of those you want on and enjoy. Works great to power the projector on also.
 

·
Premium Member
Joined
·
15,054 Posts
Works great to power the projector on also.
A switched outlet for a projector is a bad idea as switching it off before it has gone through its cool down cycle will damage the bulb.
 

·
Super Moderator
Joined
·
1,921 Posts
You can make a non-auto amplifier a switched one by using a simple relay with a 12Vdc coil and 120Vac contact. All you need is a 12V trigger to make it work, which sadly is usually only available on high-end AVRs.

A switched outlet for a projector is a bad idea as switching it off before it has gone through its cool down cycle will damage the bulb.
+1 on that!
 

·
Registered
Joined
·
65 Posts
I never shut it down that way. I always turn the projector off the proper way and then hit the button on the power center. Although my last projector I hard powered it down for 5 years and 2000 hours on the bulb. It was still going strong when I sold my last house. Im sure sometimes my wife or son forget and just hit the switch but its not the end of the world. 99% of the time we do it the "right" way.
 

·
Registered
Joined
·
50 Posts
This is my solution to the same problem - my receiver also doesn't have a signal voltage output. Using a smart strip with the sense outlet to the receiver:
http://www.belkin.com/us/p/P-F7C007/

But rather than run the subwoofer power amplifier (EP2500) off the switched outlet directly; I run a 12v plug pack (wall wart) that switches a SSR.
With the inrush current to a toroid up to 20x the operating current I don't see the smart strip lasting long otherwise.

ForumRunner_20140304_010934.png
You're not really supposed to use a zero crossing solid state relay with an inductive load as it switches at the highest load, but this unit is designed for 400A inrush (at our nominal 230v!) so I'm quite sure it will be fine. It's rated at 40A continuous with full heatsinking. The SSR is attached to a 10mm aluminium plate which should be well into the safe zone. And here in 230v land the EP2500 is 8A max. According to the data sheet I could probably run it without a heat sink at all.

Anyhow, much nicer than a mechanical relay generating emi, and contacts to wear out, without an appropriate additional arc suppression circuit. The SSR has a built in snubber.
 

·
Super Moderator
Joined
·
9,242 Posts

For those looking for a cheap and easy “plug and play” option, Adcom used to make a nifty power distro called the ACE-515 that can be found on ebay in the $100 range. The outlets are triggered by a switched outlet from your receiver. It also features off and on power sequencing. I think Panamax and Monster offer more modern units with similar features that are 12-volt triggered, but I’m sure cost quite a bit more.

Regards,
Wayne
 

·
Registered
Joined
·
281 Posts
There are a lot of options until you need to pull 20 amps or more. Im working on a DIY Trigger box for the shack now. It should be up shortly.
 

·
Registered
Joined
·
281 Posts
This is my solution to the same problem - my receiver also doesn't have a signal voltage output. Using a smart strip with the sense outlet to the receiver: http://www.belkin.com/us/p/P-F7C007/ But rather than run the subwoofer power amplifier (EP2500) off the switched outlet directly; I run a 12v plug pack (wall wart) that switches a SSR. With the inrush current to a toroid up to 20x the operating current I don't see the smart strip lasting long otherwise. You're not really supposed to use a zero crossing solid state relay with an inductive load as it switches at the highest load, but this unit is designed for 400A inrush (at our nominal 230v!) so I'm quite sure it will be fine. It's rated at 40A continuous with full heatsinking. The SSR is attached to a 10mm aluminium plate which should be well into the safe zone. And here in 230v land the EP2500 is 8A max. According to the data sheet I could probably run it without a heat sink at all. Anyhow, much nicer than a mechanical relay generating emi, and contacts to wear out, without an appropriate additional arc suppression circuit. The SSR has a built in snubber.
What relay is that? I looked at 40 amp relays and the cost was far too much to justify just for extra headroom.

The 20 amp relays i used call for a 300x300mm plate in place of a heat sink, 10mm seems small. But you are only powering 8amps so ya, you've got tons of headroom.
 

·
Registered
Joined
·
50 Posts
Earlier post gives the data sheet. It's the 40 amp option on the sheet.

10mm is the thickness of the plate. Just something i had on hand. It measures about 120x160mm, and honestly after having used it for a while now even that is overkill. To the touch you can 'just' tell that the plate it is above ambient temperature.

As long as the whole thing was satisfactorily earthed bolting the relay to the inside of an aluminium enclosure would be more than enough.
It does seem that the higher the SSR rating the lower the need for the same requirement of heat dissipation for the same given operating current, as long as both were above spec. I.e.in the case the 20A will run hotter than the 40A if both were actually operating on 8. It's really just the inrush current headroom I liked about the 40A unit.
 

·
Registered
Joined
·
281 Posts
Indeed it does, sorry I missed that.

I tried the whole using the box as a heat sink routine and while it's a great idea it isn't enough when using a SSR rated for exactly what you're pulling.

What did those 40 amp relays cost you?
 

·
Registered
Joined
·
50 Posts
Well in theory, if you look at the data sheet the 40A is happy up to 10A without any heatsink at all till 40 degrees C. I'm at 8A. And I'd say after a couple of weeks of testing my aluminium plate is lucky to reach 25c.
Cost about $60nz. Kinda dear but will last a lifetime of any amplifier I'll ever plug into it. And with virtually no load at all on the smart strip, so will that.

P.s whole setup works like a charm...
 

·
Registered
Joined
·
281 Posts
Well in theory, if you look at the data sheet the 40A is happy up to 10A without any heatsink at all till 40 degrees C. I'm at 8A. And I'd say after a couple of weeks of testing my aluminium plate is lucky to reach 25c.
Cost about $60nz. Kinda dear but will last a lifetime of any amplifier I'll ever plug into it. And with virtually no load at all on the smart strip, so will that.

P.s whole setup works like a charm...
Nice.

I tried my setup here- ( http://www.hometheatershack.com/forums/subwoofer-amps-high-pass-filters/73877-12v-trigger-box-powering-pro-audio-amps.html#post689631 )

without a heat sink and it didn't go well, but I was maxing the SSR specs. Everything was fine until I played The Art of Flight and then the things got real hot.

I would have liked to have gone with relays that were overrated for my intended use, but they jump up in price quickly.

Power I/O has a nice 25 amp relay but their shipping is 15.00! :coocoo:
 

·
Registered
Joined
·
50 Posts
Yeah I think the 20A and 40A were the same price for me so it was a no brainer.

Here's my completed effort. Tidy enough I felt, using the IEC mains sockets for in and out. The in side has an integral fuse. Put an indicator LED in too.

ForumRunner_20140318_105408.png
 

·
Registered
Joined
·
281 Posts
Yeah I think the 20A and 40A were the same price for me so it was a no brainer.

Here's my completed effort. Tidy enough I felt, using the IEC mains sockets for in and out. The in side has an integral fuse. Put an indicator LED in too.

View attachment 47539
Very clean. Feel free to add that to my other thread. One can never have too many options and examples.

What is the inrush current? Mine is rated at 220 A (60Hz 1 cycle). I ask because 1) I don't know and 2) I never saw it discussed in the other thread.

Also maybe you can clarify. As I understand it, the temperature is not the temp of the actual heat sink or even relay. It's the temperature inside the box. So, for example, I was told to put a thermometer probe found in a kitchen inside the box. If it's under the ambient temp rating all is well.

Wiring up a box is one thing. Understanding it all is another. :rubeyes:
 

·
Registered
Joined
·
100 Posts
Also maybe you can clarify. As I understand it, the temperature is not the temp of the actual heat sink or even relay. It's the temperature inside the box. So, for example, I was told to put a thermometer probe found in a kitchen inside the box. If it's under the ambient temp rating all is well.
The specs on the data sheet are for "ambient" temperatures, assuming the relay (and heatsink if applicable) are all in the same enclosure. In actuality, the critical point for temperature is at the "junction" of the relay which is right behind the metal plate. There is no practical way for you to measure that temperature, so it isn't published in many cases. In your case, the heatsink, and effectively even the plate is outside of the enclosure. So the enclosure temperature isn't going to matter much. Monitor the temperature near but not touching the heatsink. You could orient the fins vertical to get a little convective airflow.
 

·
Registered
Joined
·
281 Posts
The specs on the data sheet are for "ambient" temperatures, assuming the relay (and heatsink if applicable) are all in the same enclosure. In actuality, the critical point for temperature is at the "junction" of the relay which is right behind the metal plate. There is no practical way for you to measure that temperature, so it isn't published in many cases. In your case, the heatsink, and effectively even the plate is outside of the enclosure. So the enclosure temperature isn't going to matter much. Monitor the temperature near but not touching the heatsink. You could orient the fins vertical to get a little convective airflow.


Hmmmm.... maybe I misunderstood the guy from Power I/O. He went over the heat sink on the outside of the electrical box design and it was him who said leave a temp sensor in the box under load to see the temps.

The heat sink hits 190* under the load of a hair dryer and vacuum cleaner. That's as hot as it gets. I didn't test internal temps because my probe is metal and I didn't like the idea of inserting that in the center of a live 20 amp box.

I certainly do orientate them vertical. Those boxes were built to be on their sides and their housing will be in such a way to keep them from falling over.
 

·
Registered
Joined
·
50 Posts
What is the inrush current?
400A for 10ms. The surge current rating is inversely proportional the surge duration, so given up to theoretical 20x for toroidal trannies and my 8A 'max' load I'm looking at a worst case inrush of 160A, which leaves plenty of margin. Which is good given it's a zero crossing SSR and theory could be "worst case" every time I power it on...
 
1 - 20 of 34 Posts
Top