"Meindert Sprang" wrote in message ...
"Larry W4CSC" wrote in message
...
Never, EVER connect two transistor amplifiers in parallel......

Actually, in high power car systems, they do exactly what you just said that
cannot be done. In such systems, each channel has two amplifiers, carrying
the signal in opposite phase. The speaker is connected to both outputs. This
way, the maximum voltage that can be created across the speaker is doubled.


First of all, to do what you describe (double the max. voltage) the amplifiers
would be connected in series not in parallel. Secondly, as you say, both
amplifiers are fed the same input signal in opposite phase, not different
signals as has been suggested. This technique is called "bridging" and has
been used for years in concert hall PA systems and other applications where
LOTS of decibels are desired (such as ridiculously over powered car stereos).
Connecting two transistor amps in parallel with different input signals is
only a good idea if both the VHF and the AM/FM radios are old and you'd like
to replace them but you wife won't let you because "they work just fine". ;-)
Don't do it.

Bob

"Bruce in Alaska" wrote in message
...
In article
,
Dave wrote:

If you are a Manditory Required User, you MUST Monitor Ch.16
while
underway, unless you are in a VTS Reporting System Area.
If you are a Volintary Equipped User, then you have a choice of
either Ch. 16 or Ch. 9.

I guess I am the nosey sort because when I am in the waterway, I
monitor Ch 16,13, and 9. Never can tell when one of those tow
boats coming around a blind corner or a large container ship
coming up the Savannah River might surprise you.

Leanne
s/v Fundy

"Bruce in Alaska" wrote in message
...
In article
,
Dave wrote:

If you are a Manditory Required User, you MUST Monitor Ch.16
while
underway, unless you are in a VTS Reporting System Area.
If you are a Volintary Equipped User, then you have a choice of
either Ch. 16 or Ch. 9.

I guess I am the nosey sort because when I am in the waterway, I
monitor Ch 16,13, and 9. Never can tell when one of those tow
boats coming around a blind corner or a large container ship
coming up the Savannah River might surprise you.

Leanne
s/v Fundy

"Bob Gough" wrote in message
om...

First of all, to do what you describe (double the max. voltage) the
amplifiers
would be connected in series not in parallel.

No. It's a bridge configuration.

Secondly, as you say, both
amplifiers are fed the same input signal in opposite phase, not different
signals as has been suggested.

That makes no difference. In fact, when both aplifiers get the same,
opposite signal, it stresses the amps most, because if one outputs maximum
positive voltage, the other outputs maximum negative. With different
signals, the difference in voltages is always lower on average.

Which reminds me of a configuration that was quite popular many years ago:
to create some sense of depth in a stereo signal, some people connected a
third speaker between the 'hot' ends of the stereo outputs.

So again, it is quite possible, the only requirement is that both devices
have roughly the same power output capability.

Meindert

"Bob Gough" wrote in message
om...

First of all, to do what you describe (double the max. voltage) the
amplifiers
would be connected in series not in parallel.

No. It's a bridge configuration.

Secondly, as you say, both
amplifiers are fed the same input signal in opposite phase, not different
signals as has been suggested.

That makes no difference. In fact, when both aplifiers get the same,
opposite signal, it stresses the amps most, because if one outputs maximum
positive voltage, the other outputs maximum negative. With different
signals, the difference in voltages is always lower on average.

Which reminds me of a configuration that was quite popular many years ago:
to create some sense of depth in a stereo signal, some people connected a
third speaker between the 'hot' ends of the stereo outputs.

So again, it is quite possible, the only requirement is that both devices
have roughly the same power output capability.

Meindert

that's what I did about 13 yrs ago - never was a prob - connected the
vhf to one and the ssb to the other. added a couple of switches to
turn the cockpit connections on/off


On Thu, 05 Feb 2004 00:03:24 GMT, "Capt. Jack"
wrote:

Just wire the VHF external speaker output to the remote speaker. It won't
hurt anything if you have both the am/fm radio and vhf on at the same time,
just difficult to understand so you will have to turn the volume down on one
or the other.


"Steve" wrote in message
...
: I have a pair of speakers in the cockpit coaming for the AM/FM radio..
:
: I would like to figure out a way to connect the VHF external speaker to
one
: of these, so I can hear any calls on it in scan or monitoring of ch16.
:
: Both radios are below deck so I can only hear them in the cockpit on a
: remote speaker..
:
: I know I could just use a toggle switch, but would prefer to find a way to
: combine both outputs so the VHF would be heard over the AM/FM output.
:
: Is there a simple way to do this and prevent one unit from harming the
: other??
:
: Steve
: s/v Good Intentions
:
:
:

that's what I did about 13 yrs ago - never was a prob - connected the
vhf to one and the ssb to the other. added a couple of switches to
turn the cockpit connections on/off


On Thu, 05 Feb 2004 00:03:24 GMT, "Capt. Jack"
wrote:

Just wire the VHF external speaker output to the remote speaker. It won't
hurt anything if you have both the am/fm radio and vhf on at the same time,
just difficult to understand so you will have to turn the volume down on one
or the other.


"Steve" wrote in message
...
: I have a pair of speakers in the cockpit coaming for the AM/FM radio..
:
: I would like to figure out a way to connect the VHF external speaker to
one
: of these, so I can hear any calls on it in scan or monitoring of ch16.
:
: Both radios are below deck so I can only hear them in the cockpit on a
: remote speaker..
:
: I know I could just use a toggle switch, but would prefer to find a way to
: combine both outputs so the VHF would be heard over the AM/FM output.
:
: Is there a simple way to do this and prevent one unit from harming the
: other??
:
: Steve
: s/v Good Intentions
:
:
:

On Thu, 5 Feb 2004 16:20:26 +0100, "Meindert Sprang"
wrote:

"Larry W4CSC" wrote in message
...
Never, EVER connect two transistor amplifiers in parallel......


snip large story

Actually, in high power car systems, they do exactly what you just said that
cannot be done. In such systems, each channel has two amplifiers, carrying
the signal in opposite phase. The speaker is connected to both outputs. This
way, the maximum voltage that can be created across the speaker is doubled.

Better look closer. In "Bridged" mode, the amplifiers are in SERIES,
not in parallel....

There are four 200W amps bridged into 2-channels at 400W each in my
stepvan. These power two 12", 3-way speakers mounted to swing out on
either side of the back of the van on the full-width swinging rear
loading doors. They'll even turn around to the sides pointing the
speakers in opposite directions, if the job necessitates. Two more
speakers, massive JBL pro-sound speakers where even the 15"
bass-reflex woofers are mounted in horns, re-juvenated last year with
600W Eminence Kappa 15LFA beasts, the biggest that would fit into
these cabinets, are wheeled to go on either side of the truck, making
a wall-of-sound DJ machine I rent out to parties, car lots, anyone
needing independently-powered music/PA. A nice DJ mixer board
completes the system, powered from a 500W Tripplite inverter.

It all runs off 700AH golf cart "house" batteries I can separate from
the truck starting batteries for 12-14 hours of battery-operated
continuous music without running an engine or genset. The Honda
EU3000is 3KW inverter-technology super-quiet genset comes on to
recharge via the now-surplus 40A charger off the Amel Sharki ketch my
captain gave me.

It's all legally licensed by ASCAP and BMI to play their entire
portfolio, most of the music you hear.




Larry W4CSC

No, no, Scotty! I said, "Beam me a wrench.", not a WENCH!
Kirk Out.....

On Thu, 5 Feb 2004 16:20:26 +0100, "Meindert Sprang"
wrote:

"Larry W4CSC" wrote in message
...
Never, EVER connect two transistor amplifiers in parallel......


snip large story

Actually, in high power car systems, they do exactly what you just said that
cannot be done. In such systems, each channel has two amplifiers, carrying
the signal in opposite phase. The speaker is connected to both outputs. This
way, the maximum voltage that can be created across the speaker is doubled.

Better look closer. In "Bridged" mode, the amplifiers are in SERIES,
not in parallel....

There are four 200W amps bridged into 2-channels at 400W each in my
stepvan. These power two 12", 3-way speakers mounted to swing out on
either side of the back of the van on the full-width swinging rear
loading doors. They'll even turn around to the sides pointing the
speakers in opposite directions, if the job necessitates. Two more
speakers, massive JBL pro-sound speakers where even the 15"
bass-reflex woofers are mounted in horns, re-juvenated last year with
600W Eminence Kappa 15LFA beasts, the biggest that would fit into
these cabinets, are wheeled to go on either side of the truck, making
a wall-of-sound DJ machine I rent out to parties, car lots, anyone
needing independently-powered music/PA. A nice DJ mixer board
completes the system, powered from a 500W Tripplite inverter.

It all runs off 700AH golf cart "house" batteries I can separate from
the truck starting batteries for 12-14 hours of battery-operated
continuous music without running an engine or genset. The Honda
EU3000is 3KW inverter-technology super-quiet genset comes on to
recharge via the now-surplus 40A charger off the Amel Sharki ketch my
captain gave me.

It's all legally licensed by ASCAP and BMI to play their entire
portfolio, most of the music you hear.




Larry W4CSC

No, no, Scotty! I said, "Beam me a wrench.", not a WENCH!
Kirk Out.....

"Larry W4CSC" wrote in message
...
On Thu, 5 Feb 2004 16:20:26 +0100, "Meindert Sprang"
Actually, in high power car systems, they do exactly what you just said
that
cannot be done. In such systems, each channel has two amplifiers,
carrying
the signal in opposite phase. The speaker is connected to both outputs.
This
way, the maximum voltage that can be created across the speaker is
doubled.

Better look closer. In "Bridged" mode, the amplifiers are in SERIES,
not in parallel....

That is what I meant. I said: the speaker is connected to both outputs. What
I meant here is that one wire of the speaker is connected to the output of
one amp., the other wire of the speaker goes to the other amp.

Meindert