Plate Amplifier Load... - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 20 Old 10-28-06, 01:04 PM Thread Starter
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Plate Amplifier Load...

A rather odd question that I haven't considered before, but I'm sure somebody has the answer...

What load does a plate amplifier present to the system when attached via the high level (speaker, not RCA) input?

For the sake of argument, say I were to take an unpowered 4 ohm subwoofer, and a powered subwoofer and were to attach them in parallel to the output of an amplifier what would the load look like to my amplifier? What affect would this have on the output of the unpowered sub? I would not be passing any signal to a full range speaker.

Does anybody know the answer?

Paul
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post #2 of 20 Old 10-28-06, 02:05 PM
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Re: Plate Amplifier Load...

The speaker level input on a plate amp will probably have an input impedance on the order of 100k ohms or more so that it will not place a large load the source amp.
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post #3 of 20 Old 10-28-06, 02:16 PM Thread Starter
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Re: Plate Amplifier Load...

If this is true, and I have a 4 ohm load in parallel, virtually all of the power will be sucked up by the 4 ohm load. This would mean that adding a powered sub to the same line that has an unpowered sub should have little affect on the output of the unpowered sub, as well as little change in the load to the amp. This all assumes that my concept of how these things work has some basis in reality!

Does this also mean that I can daisy chain the powered sub from the unpowered sub with a smaller guage wire, such as a 18-20 guage?

Paul
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post #4 of 20 Old 10-28-06, 02:58 PM
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Re: Plate Amplifier Load...

The source amp will have to deliver far more current to the 4ohm speaker load than to the input of the plate amp.
yes 18-20 gauge wire is fine for this purpose.
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post #5 of 20 Old 10-28-06, 07:03 PM
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Re: Plate Amplifier Load...

Quote:
say I were to take an unpowered 4 ohm subwoofer, and a powered subwoofer and were to attach them in parallel to the output of an amplifier what would the load look like to my amplifier?
The showstopper isn't the load, it's the level. A standard line-level input to a powered sub expects just that - line level.

This is why some subs have two seperate inputs provided. High level and line level. The high level input has an attenuator ~20-30dB built in....

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post #6 of 20 Old 10-28-06, 07:08 PM
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Re: Plate Amplifier Load...

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brucek wrote: View Post
The showstopper isn't the load, it's the level. A standard line-level input to a powered sub expects just that - line level.

This is why some subs have two seperate inputs provided. High level and line level. The high level input has an attenuator ~20-30dB built in....

brucek
Yes or the input will be seriously overloaded.I ve seen the use of 680k resistors in series with the input to get the required attenuation.
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post #7 of 20 Old 10-28-06, 07:58 PM Thread Starter
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Re: Plate Amplifier Load...

Quote:
aceinc wrote: View Post
What load does a plate amplifier present to the system when attached via the high level (speaker, not RCA) input?
My idea is to attach to the Hi-level in not the RCA (Low level) in. What load does the "high level in" present to the amplifier driving it?

Paul
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post #8 of 20 Old 10-28-06, 08:32 PM
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Re: Plate Amplifier Load...

Quote:
What load does the "high level in" present to the amplifier driving it?
None to speak of....... brucek
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post #9 of 20 Old 10-28-06, 08:37 PM Thread Starter
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Re: Plate Amplifier Load...

So what I posited earlier, that the unpowered 4 ohm sub would get all the power, and I can use a smaller guage wire to daisy chain the powered sub is reasonable iyo?

Paul
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post #10 of 20 Old 10-28-06, 08:56 PM
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Re: Plate Amplifier Load...

Quote:
aceinc wrote: View Post
So what I posited earlier, that the unpowered 4 ohm sub would get all the power, and I can use a smaller guage wire to daisy chain the powered sub is reasonable iyo?

Paul
I will give the same answer as in post #4 YES it is ok.
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