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From: William Sommerwerck on 22 Jul 2010 08:00
>> 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.

> You are VERY WRONG on this.

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).


From: Allodoxaphobia on 22 Jul 2010 09:04
On Wed, 21 Jul 2010 18:53:58 -0700, William Sommerwerck wrote:

<- snippage->
>
> Assuming that both channels have the same output impedance, and the output
> levels are closely matched,

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

> then (if the outputs are directly paralleled)
> there will be /no/ current flow from one channel into the other, ....

Jonesy
From: whit3rd on 22 Jul 2010 10:36
On Jul 21, 6:55 am, "j r powell" <nos...(a)invalid.xy> wrote:

> I have a small stereo amplifier which came with two tiny 4ohm 3watt speakers.
> I'd like to combine the two channels of the amp in order to drive one, slightly
> larger, 8ohm 4watt speaker.
> The amp is of the non-bridgeable type,

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.
From: stratus46 on 23 Jul 2010 02:15
On Jul 22, 5:00 am, "William Sommerwerck" <grizzledgee...(a)comcast.net>
wrote:
> >> 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.
> > You are VERY WRONG on this.
>
> 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).

If the output voltage is _slightly_ not matched, each amp will attempt
to correct it and push large currents into each other. HEAT. BANG.

G²
From: GregS on 23 Jul 2010 09:22
In article <i26u7v$6o1$1(a)speranza.aioe.org>, "j r powell" <nospam(a)invalid.xy> wrote:
>Hi,
>I have a small stereo amplifier which came with two tiny 4ohm 3watt speakers.
>I'd like to combine the two channels of the amp in order to drive one, slightly
>
>larger, 8ohm 4watt speaker.
>The amp is of the non-bridgeable type, so I assume parallel wiring would be
>required - combining the two outputs together. I have read that small resistors
>
>are required in parallel configuration, to enable proper current sharing
> between
>the amplifiers, as without them the two amps would fight each other and
>overheat. Can anyone tell me the correct values for these resistors, and where
>they should be placed?
>
>thanks,
>jamie.

You forgot to give the power.

From quick reading of posts, to get more sound you can put 2- 8 ohm
speakers in parallel which will give 6 db increase over one
8 ohm.

You can bridge, say put 1-2 ohm resistors in series
with the speaker and use a bridge transformer on the input.
If you gave the minimum ohm spec of the amp, I could be more specific.
You also did not specify the output
type if the amplifier. Are the channels allready bridged ?

greg
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