Mono signal from stereo loudspeakers
 

Can someone remind me how to do a simple job please?

I have a motorcycle (K1200LT) with loudspeakers front and rear, with
independant volume controls. These are stereo fed from a Becker readio
cassette unit up front.

I want to provide mono (L+R) feeds into a helmet without stuffing the
amplifiers or affecting the loudspeaker output. So do I use a couple of
capacitors from the two lives or what? It's so long since I played with this
sort of thing.


--
AJL Electronics (G6FGO) Ltd : Satellite and TV aerial systems
http://www.classicmicrocars.co.uk : http://www.ajlelectronics.co.uk

Mono signal from stereo loudspeakers
 

I want to provide mono (L+R) feeds into a helmet without stuffing the
amplifiers or affecting the loudspeaker output. So do I use a couple of
capacitors from the two lives or what? It's so long since I played with
this
sort of thing.

It would be easier to just wire up in stereo from the front speakers. Is
there a reason you can only have mono in the helmet? If so, just running off
the left would be easy, and don't play any Queen!

Christian.

Mono signal from stereo loudspeakers
 

Andy Luckman (AJL Electronics) wrote:
Can someone remind me how to do a simple job please?

I have a motorcycle (K1200LT) with loudspeakers front and rear, with
independant volume controls. These are stereo fed from a Becker readio
cassette unit up front.

I want to provide mono (L+R) feeds into a helmet without stuffing the
amplifiers or affecting the loudspeaker output. So do I use a couple of
capacitors from the two lives or what? It's so long since I played with this
sort of thing.


use a couple of 220ohm 5 watt resistors from the stereo outputs to a
mono headphone output.

Hopefully - but its by no mans a dead cert, the earth side of the stereo
outputs is actual bike earth.

If they are not, use 4 x 100ohm resistors - two from each live to 'mono
live' and two from each 'other live' to the headphone earth..

Mono signal from stereo loudspeakers
 

Hopefully - but its by no mans a dead cert, the earth side of the stereo
outputs is actual bike earth.

Even if not (and probably not, unless it is an ancient low wattage stereo),
a single headed output to earth is likely to be acceptable, although there
might be some DC component that needs filtering out by a cap.

Christian.

Mono signal from stereo loudspeakers
 

Christian McArdle wrote:
Hopefully - but its by no mans a dead cert, the earth side of the stereo
outputs is actual bike earth.

Even if not (and probably not, unless it is an ancient low wattage stereo),
a single headed output to earth is likely to be acceptable, although there
might be some DC component that needs filtering out by a cap.

Christian.


Agreed, but an extra resistor is cheaper than an extra capacitor.

Mono signal from stereo loudspeakers
 

The Natural Philosopher wrote:


Hopefully - but its by no mans a dead cert, the earth side of the stereo
outputs is actual bike earth.

If they are not, use 4 x 100ohm resistors - two from each live to 'mono
live' and two from each 'other live' to the headphone earth..

Actually, with amplifiers powered from low voltages, you can't always
assume that one side of the speaker is earthed.

In order to get high volume levels, some manufacturers use 'bridged'
amplifiers where each terminal of the speaker is driven in anti-phase to
the other, so the maximum voltage swing as seen by the speaker is twice
that of the battery.

They use two anti-phased amplifiers to drive each speaker, but as the
amplifiers can be built for tuppence, that's considered a good trade
off.

Mono signal from stereo loudspeakers
 

In article ,
The Natural Philosopher wrote:
Andy Luckman (AJL Electronics) wrote:
Can someone remind me how to do a simple job please?

I have a motorcycle (K1200LT) with loudspeakers front and rear, with
independant volume controls. These are stereo fed from a Becker readio
cassette unit up front.

I want to provide mono (L+R) feeds into a helmet without stuffing the
amplifiers or affecting the loudspeaker output. So do I use a couple
of capacitors from the two lives or what? It's so long since I played
with this sort of thing.


use a couple of 220ohm 5 watt resistors from the stereo outputs to a
mono headphone output.

If using 220 ohm resistors they needn't be anything like 5 watts - even
assuming an 'HT' rail of 12 volts and a dead short. Standard 0.6w metal
oxide types will be fine.

--
*Where do forest rangers go to "get away from it all?"

Dave Plowman London SW
To e-mail, change noise into sound.

Mono signal from stereo loudspeakers
 

Andy Luckman (AJL Electronics) wrote:

Can someone remind me how to do a simple job please?

I have a motorcycle (K1200LT) with loudspeakers front and rear, with
independant volume controls. These are stereo fed from a Becker readio
cassette unit up front.

I want to provide mono (L+R) feeds into a helmet without stuffing the
amplifiers or affecting the loudspeaker output. So do I use a couple of
capacitors from the two lives or what? It's so long since I played with this
sort of thing.

Because you cant asume the amp isnt bridged output you need to use 4
resistors. Using 2 may kill it.

Amp L- to helmet -
Amp R- to helmet -
Amp L+ to helmet +
Amp R+ to helmet +

via one resistor in each case. 100 ohm probably better than 220 in this
case.


NT

Mono signal from stereo loudspeakers
 

If using 220 ohm resistors they needn't be anything like 5 watts - even
assuming an 'HT' rail of 12 volts and a dead short. Standard 0.6w metal
oxide types will be fine.

The "HT" rail is quite likely to be in excess of 12V, especially if the
power output is reasonable (i.e. much in excess of 10W rms/channel).

Christian.

Mono signal from stereo loudspeakers
 

In article ,
Christian McArdle wrote:
If using 220 ohm resistors they needn't be anything like 5 watts - even
assuming an 'HT' rail of 12 volts and a dead short. Standard 0.6w metal
oxide types will be fine.

The "HT" rail is quite likely to be in excess of 12V, especially if the
power output is reasonable (i.e. much in excess of 10W rms/channel).

No - the usual way in a car radio is via bridged output amps if more than
approx 6 watts. Some earlier designs improved on this with an output
transformer.

Normal transformerless outputs from 14 volts into 4 ohms are actually less
than 6 watts, though, regardless of ad speak. Bridging those can give
approx 3 times the power output still into 4 ohms.

--
*Some days we are the flies; some days we are the windscreen.*

Dave Plowman London SW
To e-mail, change noise into sound.

Mono signal from stereo loudspeakers
 

Dave Plowman (News) wrote:
In article ,
Christian McArdle wrote:

If using 220 ohm resistors they needn't be anything like 5 watts - even
assuming an 'HT' rail of 12 volts and a dead short. Standard 0.6w metal
oxide types will be fine.

The "HT" rail is quite likely to be in excess of 12V, especially if the
power output is reasonable (i.e. much in excess of 10W rms/channel).

No - the usual way in a car radio is via bridged output amps if more than
approx 6 watts. Some earlier designs improved on this with an output
transformer.

Normal transformerless outputs from 14 volts into 4 ohms are actually less
than 6 watts, though, regardless of ad speak. Bridging those can give
approx 3 times the power output still into 4 ohms.

Higher power amps use a switch mode voltage booster to supply the
bridged output amps.


NT

Mono signal from stereo loudspeakers
 

In article . com,
wrote:
The "HT" rail is quite likely to be in excess of 12V, especially if
the power output is reasonable (i.e. much in excess of 10W
rms/channel).

No - the usual way in a car radio is via bridged output amps if more
than approx 6 watts. Some earlier designs improved on this with an
output transformer.

Normal transformerless outputs from 14 volts into 4 ohms are actually
less than 6 watts, though, regardless of ad speak. Bridging those can
give approx 3 times the power output still into 4 ohms.

Higher power amps use a switch mode voltage booster to supply the
bridged output amps.

Indeed - but not likely on a motorbike?

--
*If a pig loses its voice, is it disgruntled?

Dave Plowman London SW
To e-mail, change noise into sound.

Mono signal from stereo loudspeakers
 

Roly wrote:
The Natural Philosopher wrote:

Hopefully - but its by no mans a dead cert, the earth side of the stereo
outputs is actual bike earth.

If they are not, use 4 x 100ohm resistors - two from each live to 'mono
live' and two from each 'other live' to the headphone earth..

Actually, with amplifiers powered from low voltages, you can't always
assume that one side of the speaker is earthed.


That is precisely why I said all that.

Fule.


I din;t feel the need to display my experience of bridged audio
amplifier design either.

Mono signal from stereo loudspeakers
 

Dave Plowman (News) wrote:
In article ,
The Natural Philosopher wrote:
Andy Luckman (AJL Electronics) wrote:
Can someone remind me how to do a simple job please?

I have a motorcycle (K1200LT) with loudspeakers front and rear, with
independant volume controls. These are stereo fed from a Becker readio
cassette unit up front.

I want to provide mono (L+R) feeds into a helmet without stuffing the
amplifiers or affecting the loudspeaker output. So do I use a couple
of capacitors from the two lives or what? It's so long since I played
with this sort of thing.


use a couple of 220ohm 5 watt resistors from the stereo outputs to a
mono headphone output.

If using 220 ohm resistors they needn't be anything like 5 watts - even
assuming an 'HT' rail of 12 volts and a dead short. Standard 0.6w metal
oxide types will be fine.

Yeah...I just grabbed that from my days of shoving headphone sockets on
100W amps and 400W bridged amps..

Mono signal from stereo loudspeakers
 

Dave Plowman (News) wrote:
In article . com,
wrote:
The "HT" rail is quite likely to be in excess of 12V, especially if
the power output is reasonable (i.e. much in excess of 10W
rms/channel).

No - the usual way in a car radio is via bridged output amps if more
than approx 6 watts. Some earlier designs improved on this with an
output transformer.

Normal transformerless outputs from 14 volts into 4 ohms are actually
less than 6 watts, though, regardless of ad speak. Bridging those can
give approx 3 times the power output still into 4 ohms.

Higher power amps use a switch mode voltage booster to supply the
bridged output amps.

Indeed - but not likely on a motorbike?

Anything is likely on a motorbike. The whole concept of a motorbike is
unlikely to start with.

Its probably a GoldStar with a 400W amp in one of the panniers....

Mono signal from stereo loudspeakers
 

In article ,
The Natural Philosopher wrote:


Its probably a GoldStar with a 400W amp in one of the panniers....

As per previous post, it is a BMW K1200LT with factory fitted audio system.
It is a Becker radio/cassette unit with dashboard remote control. It feeds 4
speakers and each pair has its own feed.

--
AJL Electronics (G6FGO) Ltd : Satellite and TV aerial systems
http://www.classicmicrocars.co.uk : http://www.ajlelectronics.co.uk

Mono signal from stereo loudspeakers
 

In article ,
Andy Luckman (AJL Electronics) wrote:

I want to provide mono (L+R) feeds into a helmet without stuffing the
amplifiers or affecting the loudspeaker output.

Well it looks like it will be 4 off resistors then. I have got a Starcom
intercom unit coming which has an isolated speaker takeoff point. I have
asked the manufacturers if the unit can be switched into mono, which will
make it easy.

Many thanks for all the suggestions. I really should have known the answer
myself, but old age fuddles the brain!

--
AJL Electronics (G6FGO) Ltd : Satellite and TV aerial systems
http://www.classicmicrocars.co.uk : http://www.ajlelectronics.co.uk

Mono signal from stereo loudspeakers
 

In article , Christian McArdle
wrote:

It would be easier to just wire up in stereo from the front speakers. Is
there a reason you can only have mono in the helmet?

An extremely good reason!

If so, just running off
the left would be easy, and don't play any Queen!

I tried it with a portable Minidisc player and some tracks sound VERY
unusual. It's interesting to note that some vocals seem to be exclusively on
one channel.

--
AJL Electronics (G6FGO) Ltd : Satellite and TV aerial systems
http://www.classicmicrocars.co.uk : http://www.ajlelectronics.co.uk

Mono signal from stereo loudspeakers
 

In article , Dave Plowman (News)
wrote:

No - the usual way in a car radio is via bridged output amps if more than
approx 6 watts. Some earlier designs improved on this with an output
transformer.

Not sure about this one, but I believe it is the same or similar as fitted
to BMW cars. E36 has some meaning apparently. The manufacturer is Becker.

--
AJL Electronics (G6FGO) Ltd : Satellite and TV aerial systems
http://www.classicmicrocars.co.uk : http://www.ajlelectronics.co.uk

Mono signal from stereo loudspeakers
 

In article ,
Andy Luckman (AJL Electronics) wrote:
No - the usual way in a car radio is via bridged output amps if more
than approx 6 watts. Some earlier designs improved on this with an
output transformer.

Not sure about this one, but I believe it is the same or similar as
fitted to BMW cars. E36 has some meaning apparently. The manufacturer is
Becker.

The E36 is a 3 Series made from approx 90-99. If the radio is an all in
one unit - most likely for a motor bike - it will likely have four speaker
outputs each of 18 watts, That's been pretty well the standard for some
time. Higher power ones usually have external amps, but I don't think this
was factory fit on an E36.

--
*Why is the man who invests all your money called a broker? *

Dave Plowman London SW
To e-mail, change noise into sound.

Mono signal from stereo loudspeakers
 

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember The Natural Philosopher
saying something like:

Its probably a GoldStar with a 400W amp in one of the panniers....

If it was a Goldstar the panniers would most likely contain oil.
--

Dave