Paralleled Amplifier Wiring

J

j r powell

Guest
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.
--

PS. If your name is Dave Plowman, do not reply.
 
"j r powell" <nospam@invalid.xy> wrote in message
news:i26u7v$6o1$1@speranza.aioe.org...
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.
--

PS. If your name is Dave Plowman, do not reply.
Click to expand...
How very rude ... d :-\

Arfa
 
"j r powell" <nospam@invalid.xy> wrote in message
news:i26u7v$6o1$1@speranza.aioe.org...
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.
--

PS. If your name is Dave Plowman, do not reply.
Click to expand...
How very rude ... d :-\

Arfa
 
"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
news:KHL1o.42481$AS4.24133@hurricane...
"j r powell" <nospam@invalid.xy> wrote in message
news:i26u7v$6o1$1@speranza.aioe.org...
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.
--

PS. If your name is Dave Plowman, do not reply.



How very rude ... d :-\
Click to expand...
Well... he follows me around usenet and trolls me.
 
On 7/21/2010 6:55 AM j r powell spake thus:

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?
Click to expand...
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).


--
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.

- Comment from an article on Antiwar.com (http://antiwar.com)
 
"David Nebenzahl" <nobody@but.us.chickens> wrote in message
news:4c478f88$0$2381$822641b3@news.adtechcomputers.com...
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).
Click to expand...
I have, but then the audio output is too quiet for my requirements.
 
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.
Click to expand...
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.
 
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:i283ln$l13$1@news.eternal-september.org...
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.
Click to expand...
A small increase is better than nothing.
 
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.
Click to expand...
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
 
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:i285k5$s14$1@news.eternal-september.org...
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.
Click to expand...
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:

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:i285k5$s14$1@news.eternal-september.org...

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.

Fitting resistors is hardly a lot of work. I just need someone who knows their
stuff, to answer my original question.
Click to expand...
So, William, what is the correct answer here (value of resistors)? I'm
curious now, too.


--
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.

- Comment from an article on Antiwar.com (http://antiwar.com)
 
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.

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

So, William, what is the correct answer here (value of resistors)? I'm
curious now, too.
Click to expand...
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?
 
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:i288c2$65c$1@news.eternal-september.org...
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.

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

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

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?
Click to expand...

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.

T





--- news://freenews.netfront.net/ - complaints: news@netfront.net ---
 
"j r powell"
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.
Click to expand...
** The only way to go here is to use "bridge mode".

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


I have read that small resistors are required in parallel configuration,
to enable proper current sharing between the amplifiers,
Click to expand...
** Complete crap.

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, 5:56 pm, "j r powell" <nos...@invalid.xy> wrote:
"William Sommerwerck" <grizzledgee...@comcast.net> wrote in message

news:i283ln$l13$1@news.eternal-september.org...

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.
Click to expand...
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˛
 
On Jul 21, 7:28 pm, "William Sommerwerck" <grizzledgee...@comcast.net>
wrote:
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.
Click to expand...
You are VERY WRONG on this.

There is also the possibility that, even with the levels matched,
the amps
might not "like" looking at each other.
Click to expand...
Virtually a certainty.

"Buy a decent amplifier that delivers the power you need." -- The
Lady from
Philadelphia
Click to expand...
This is good advice.

G˛
 
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.
Click to expand...
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).
 
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,
Click to expand...
.. 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, ....
Click to expand...
Jonesy
 
On Jul 21, 6:55 am, "j r powell" <nos...@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,
Click to expand...
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.
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top