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Discussion Starter · #1 ·
Looking for some advice......I am in the process of retrofitting a home theater into an already finished basement. I intend to pull off the baseboard, run 12 gauge speaker wire behind it, and terminate the speaker wire on a "decora" 5-way speaker connector wall plate on a box in the wall. However, as I started searching for speaker connector plates, I have noticed that some companies list wire size limitations as well as power handling limits and some do not. For example, in speaking with RAM electronics, I was advised not to use their 5-way connectors for any more than 150 W. However, Parts Express has said they do not necessarily specify a power limit for their wall plates.


For my mains, center, and surrounds this isn't an issue. However, my dilemna is that I have a passive powered sub with a rack amp rated for 500 W RMS (ACI Maestro). I need to run speaker wire between my rack and the subwoofer location. I prefer to have the clean look and additional into the room cable length flexibility provided by a connector wall plate rather than try to stuff excess length into the box and use a hole / grommet.


Is this power handling issue a legitimate concern? I would think that high power handling would only be required for brief transients. Has anyone overheated a wall plate connector by using too much power?
 

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1. The power ratings on amps and speakers are so much higher than the electrical power that is actually running through a speaker it's ridiculous.


2. As long as you are using a decent connector type such as a banana plug or screw terminal, I can't envision a problem in my wildest imagination. Even a flimsy spring terminal would not be dangerous but could effect sound quality due to poor contact.


I can tell you are into overkill with 12ga speaker wires but really, have no fear.
 

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I agree with greywolf. Look at the connectors and wires inside some audio equipment and you will realize that the wall plates should be plenty. The speaker out connections on most equipment aren't as heavy duty as many wall plates available and they are just as much part of the conductive chain as a wall plate would be.


Hope this helps,

Brian
 

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I am not an electrical engineer, but watts = volts x amps. I


Using 110 volt household electricity and an appliance needing 150 watts, I assume that means 110 volts x 1.36 amps = 150 watts.


But with an HT amplifier putting out 150 watts, what are the volts and amps? Or does 150 speaker watts mean something different than 150 household watts?

Take Aim
 

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I think that wire has resistance and maybe something called impedance built into it. A long run might alter the impedance of a speaker. I don't know if that negatively affects a speaker or the amp, but a lot of folks use heavy wire.


For no particularly good reason, but that Larry Chanin suggested it, I went with 12-2 speaker wire from PartsExpress. It has two separate colored wires, red and black, is stranded and not solid copper wire, unshielded, and makes one twist every 6" or so. On the 500' spool is says "sound & security cable." and is made by the Carol Company.


The speaker wire looks like CAT5e, only a little thicker.


The jacket is gray, covers the two wires, and the spool says "in wall." It is easy to pull and it certainly suits my needs. Thanks Larry.


I see lots of speaker wires having two wires that are attached and with no jacket around them. I guess one could use it inwall, but I just prefer the jacket and the twisting. An interesting article is at www.roger-russell.com/wire/wire.htm

Take Aim
 

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Look at the wire guage/distance/speaker impedence chart in your link and you'll see why I said 12ga is overkill. You'll also notice no mention of twisting. Look at the sticker on the back of your amp for its current specifications and you'll see why I said the power output claims are exaggerated.
 

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To repeat, I'm no electrical engineer. But, in an add for the B&K Reference 200.7 amplifier, it says it is a "high current amplifier." Assuming it is a 200 watt per channel amplifier, how high is "high"? I have no idea what that means.

Take Aim
 

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Quote:
Originally Posted by takeaim
For no particularly good reason, but that Larry Chanin suggested it, I went with 12-2 speaker wire from PartsExpress. It has two separate colored wires, red and black, is stranded and not solid copper wire, unshielded, and makes one twist every 6" or so. On the 500' spool is says "sound & security cable." and is made by the Carol Company.


The speaker wire looks like CAT5e, only a little thicker.


The jacket is gray, covers the two wires, and the spool says "in wall." It is easy to pull and it certainly suits my needs. Thanks Larry.
Quote:
Originally Posted by greywolf
Look at the wire guage/distance/speaker impedence chart in your link and you'll see why I said 12ga is overkill.
Hi,


Pat is undoubtedly correct that 12 gauge wire is overkill for typical speakers in an average sized room with average length runs.


However, in my situation I intended to install a number of tactile transducers powered by amplifiers putting out 2,100 watts each. For that application 12 guage is appropriate. Rather than paying for multiple rolls of in-wall speaker wire of different guages and having a lot of surplus left over on each roll, I choose to buy one roll of 12 guage to satisfy all my speaker wire needs.


Getting back to the original poster's question, I have the same type of 5-way terminals for my speaker wires and my transducers, and I have not experienced any problems. However, I have no idea what the rating is. (I don't know if they are Niles brand as in the photo, but they look the same.)


Larry
 

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Quote:
Originally Posted by takeaim
I think that wire has resistance and maybe something called impedance built into it. A long run might alter the impedance of a speaker. I don't know if that negatively affects a speaker or the amp, but a lot of folks use heavy wire.
Hi Jim,


The type and length of speaker wire does not alter the speaker impedance. It mainly effects the amount of power delivered to the speaker. If the resistance of the wire is high due to small gauge and/or long lengths, a portion of the amplifier's rated power will be dissipated in the wire and not reach the speaker. This was discussed in the article you referenced. The article goes on to describe that the speaker's frequency response might also be affected.


Larry
 

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Quote:
Originally Posted by takeaim
To repeat, I'm no electrical engineer. But, in an add for the B&K Reference 200.7 amplifier, it says it is a "high current amplifier." Assuming it is a 200 watt per channel amplifier, how high is "high"? I have no idea what that means.

Take Aim
Hi Jim,


I'm not sure, but I believe that a high current amplifier is able to safely deliver power to a speaker as the speaker's impedance drops. As was discussed in the article you referenced, the impedance of a speaker varies with frequency. The so-called nominal impedance of a speaker is a sort of average value over the frequency range of the speaker, not the actual impedance at a specific frequency.


As the impedance of a speaker drops, the current it demands from the amplifier increases, and so does the power drawn from the amplifier. In your example the B&K amplifier is rated for 200 watts @ 8 ohms and 375 watts @ 4 ohms. This means that the amp can safely deliver power into 4 ohm loads. So I believe in the latter case the amp would be delivering about 9.7 amps to that channel, at least momentarily. In the real world I doubt our ears would be able to sustain the sound levels generated at 375 watts. Of course, speaker rated at 150 watts might give up before your ears. ;)


Larry
 

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A bass shaker is a different animal. It's not moving air, it's moving furniture. Still, 2 Ohm impedence speakers are in the chart. A shaker is more likely to be set to actually use the power it's rated for since it's harder to hurt a chair than an ear.
 

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Quote:
Originally Posted by greywolf
A bass shaker is a different animal. It's not moving air, it's moving furniture. Still, 2 Ohm impedence speakers are in the chart. A shaker is more likely to be set to actually use the power it's rated for since it's harder to hurt a chair than an ear.
Hi Pat,


Agreed, but it is a closer match to the original poster's question regarding suitable wiring and connection plates for a 500 watt passive subwoofer, than a conventional speaker would be.


Larry
 

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But a 500W passive subwoofer means it can handle 500W(not that that is actually true), not that it will be fed 500W. The speaker impedence is still the determinator of the wire size and connector heft. People think they are pumping out a whole lot more power than they really are. For example, I have an amp that says it outputs 110W per channel on 7 channels. The label on the back says it takes under 500 watts from the power cord. It also is less than 100% efficient as I can use it for a space heater. Amp output figures are a joke.
 

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Quote:
Originally Posted by greywolf
But a 500W passive subwoofer means it can handle 500W(not that that is actually true), not that it will be fed 500W. The speaker impedence is still the determinator of the wire size and connector heft. People think they are pumping out a whole lot more power than they really are. For example, I have an amp that says it outputs 110W per channel on 7 channels. The label on the back says it takes under 500 watts from the power cord. It also is less than 100% efficient as I can use it for a space heater. Amp output figures are a joke.
Hi Pat,


Yes, I agree again.


Here's the manufacturer's wire size recommendations for the original poster's subwoofer.

Quote:
Minimum Recommended wire gauges are as follows:

Under 15ft - - - 16awg

Under 30ft - - - 14awg

Over 30ft - - - 12awg


It never hurts to use a thicker gauge wire!
Larry
 

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Yep! Pretty close to recommendations for a 2 Ohm speaker. The sub probably isn't a 2 Ohm but the manufacturer undoubtedly built a little extra into the spec.
 

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Discussion Starter · #16 ·
Thanks for all the input guys. It did not seem logical to me that these connector plates would have power handling limits any different from a typical binding post but I figured I better ask. It makes one wonder why the manufacturer includes this specification at all (CYA perhaps?? :p ).
 
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