Paralleled Amplifier Wiring

How very rude ... d :-\

Arfa

How very rude ... d :-\

Arfa

Well... he follows me around usenet and trolls me.

On 7/21/2010 6:55 AM j r powell spake thus:

slightly

resistors

between

Have you tried simply using a pair of 8-ohm speakers with the amp? Chances are they'd work (less power, but shouldn't harm the amp).

I have, but then the audio output is too quiet for my requirements.

I'm not being sarcastic -- but how do you know that paralleling the outputs will produce a significant increase in power? Ignoring the very pertinent question of how to do this /correctly/, the most you could get is a 3dB increase, which is plainly audible, but hardly a large increase.

A small increase is better than nothing.

No, it isn't. Not when it requires a lot of work, and will be only slightly audible.

"Forget about the whole thing." -- The Lady from Philadelphia

Fitting resistors is hardly a lot of work. I just need someone who knows their stuff, to answer my original question.

On 7/21/2010 6:10 PM j r powell spake thus:

So, William, what is the correct answer here (value of resistors)? I'm curious now, too.

slightly

their

I don't see where I'm obliged to provide an answer, but here's what I believe, to the best of my understanding...

Assuming that both channels have the same output impedance, and the output levels are closely matched, then (if the outputs are directly paralleled) there will be /no/ current flow from one channel into the other, and the total amount of current that /could/ be delivered will be doubled. But if the load impedance remains the same, there will be no increase in current flow and no increase in volume level. You would need a speaker of half the impedance to gain more power.

I think that's correct. Anybody want to agree or disagree?

Well, you sure don't want to use resistors to match it. Any gain would just be converted to heat.

ASSuming the impedance's were the same and you paralleled the outputs, you would need a 1.5 to 8 ohm transformer to match the speaker.

But I agree with the first premise, it's hardly worth the 3 dB you might gain.

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puts

nt

The increase will be 0. Changing from 4 ohms to 8 will cut the power in half because the voltage stayed the same and the current cut in half because of the impedance change. Paralleling the amps raises current capacity - which you don't need - and does nothing to increase the voltage. In fact, your resistors will reduce it slightly. You need a bigger amp.

G=B2

"j r powell"

Parallel wiring of the outputs is not only 100% useless it will almost certainly destroy both amplifier channels.

There is such of lot of it on the net you know.

.... Phil

I made a mistake -- for some reason I assumed this was a tube amp. (I don't know why.)

Regardless, if the output levels are closely matched, one amp /will not/ pump current into the other. But to gain any increase in power, you'd have to use a lower-impedance speaker.

There is also the possibility that, even with the levels matched, the amps might not "like" looking at each other.

"Buy a decent amplifier that delivers the power you need." -- The Lady from Philadelphia

On Jul 21, 7:28=A0pm, "William Sommerwerck" wrote: > I made a mistake -- for some reason I assumed this was a tube amp. (I don't > know why.) >

You are VERY WRONG on this.

Virtually a certainty.

This is good advice.

G=B2

Why? You haven't changed the output voltage. If the amps are solid state, their source impedance is much lower than that of the load, so there wouldn't be any significant increase in current flow (that I know).

.. and, assuming both outputs are _exactly_ in phase,

Jonesy

The power limit might not be the amplifier output stages, but the common power supply. So, you'd just connect to the left channel and ignore the other.

Alternately, you could transformer-couple and put the left and right channel outputs in series (not parallel), to get good drive into an 8 ohm speaker. Transformers, though, aren't cheap. Doing this only gains you 3 dB, it's scarcely worth the effort.

More efficient speakers (two of 'em, not one) is the preferred solution if you don't like what you've got.