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Old 3rd February 2007, 05:26 AM   #1
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Default Two Amps Powering One Driver

Hello, I'd just like to ask a couple of elementary questions if I may.

An 8 ohm speaker rated at 500 watts is hooked up to two amps in parallel. In both cases, the amps are delivering the same program material.

A) In one case, amp A is 200 watts, the second amp is 20 watts. What happens when they both deliver full power? I mean to both amps and speaker.


B) Both amps are rated 100 watts. What happens to them and the speaker?

I'm interested if both amps are tube amps instead of solid state, would that change anything?
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Old 3rd February 2007, 02:11 PM   #2
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A)

B) Assuming they are identical amplifiers that can even be paralleled, you won't gain anything. You will still have the same voltage swing on the outputs, but twice the current capability.

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Old 3rd February 2007, 02:16 PM   #3
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I can only agree with theAnonymous1 .....

A) The 20W amp will most likely get fried and proberly cause the 100W amp to get fried too

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Old 3rd February 2007, 10:06 PM   #4
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Old 3rd February 2007, 10:20 PM   #5
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Hi,

Also..
If we are talking about paralleling two amps they must be identical, very much so infact.
Imagine the amps has slightly different phase response, usually common in the ends of audioband. Large currents will then travel betwen amps and......
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Old 3rd February 2007, 10:27 PM   #6
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Hi kelticwizard,
Quote:
A) In one case, amp A is 200 watts, the second amp is 20 watts. What happens when they both deliver full power? I mean to both amps and speaker.
The 20 W amplifier bocomes another load, a low resistance one. The excess voltage will dump into the lower supplies through the outputs or drivers (breaking down in reverse) or the flyback diodes.

Quote:
B) Both amps are rated 100 watts. What happens to them and the speaker?
If the gains are identical, there will be some form of current sharing. If even so much as the phase shifts between them, one becomes an unhappy load. Excessive currents will flow.

Quote:
I'm interested if both amps are tube amps instead of solid state, would that change anything?
Yes, if the amp is made to do this and the gains are the same, you change taps and the relatively high output resistance will current share. A tube amp with very high damping factor may have issues with this, or if the channels do not have the same gain (ie a fault with one side).

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Old 3rd February 2007, 10:40 PM   #7
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I sincerely doubt that this would work with any type of amplifier.

What would be the advantage of even trying it?
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Old 3rd February 2007, 10:47 PM   #8
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Hi Joe,
Many tube amps were set up to do that. Connect both together on the 16 R tap and connect an 8R speaker there also.

Quote:
What would be the advantage of even trying it?
More power!

-Chris
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Old 3rd February 2007, 11:05 PM   #9
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Chris,

Wouldn't it be simpler just to use a higher powered amplifier? When one looks at the possible problems involved it just isn't logical to do it. What happens when/if one amplifiers lets out some magic smoke? Damage will result and this damage would be more extensive than it would be with just one amplifier in the mess. Well, there is driver damage also that more than likely will result. Call me cautious but I will opt for a larger amplifier every time but then again thats just me.
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Old 3rd February 2007, 11:10 PM   #10
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Hi Joe,
Quote:
Wouldn't it be simpler just to use a higher powered amplifier?
Absolutely!

There was a time when high powered amps were terribly expensive and rare. The solution was to use a couple stereo units as mono units. I'm talking about the 50's and possibly early 60's. Not now.

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