Amplifier switching
 

I've got two amplifiers and I'd like to switch between them. At the
moment I'm plugging/unplugging at the speakers. For reasons of cable
management, convenience and neatness I'd like to use a switch. QED did
one a while ago but it's discontinued, and replaced with a wall switch
which is too 'embedded' for my liking, and pricey.

I was having a look in Wickes for a suitable switch, and it looks as
though a four gang light switch would do it (8 wires in, four wires
out), but this has four switches.

Ideally I'd like one switch - amplifier A, or amplifier B.

Any ideas?

Thanks, Rob

Amplifier switching
 

"Rob" wrote in message
...
I've got two amplifiers and I'd like to switch between them. At the
moment I'm plugging/unplugging at the speakers. For reasons of cable
management, convenience and neatness I'd like to use a switch. QED did
one a while ago but it's discontinued, and replaced with a wall switch
which is too 'embedded' for my liking, and pricey.

I was having a look in Wickes for a suitable switch, and it looks as
though a four gang light switch would do it (8 wires in, four wires
out), but this has four switches.

Ideally I'd like one switch - amplifier A, or amplifier B.

Any ideas?

Thanks, Rob


The important thing in this scenario Rob is to be sure you have a *break
before make* switch and preferably one which places the 'other' amplifer
under a load when it's switched away from. in a both amps *on*
situation. (I bet Fekki Norsaam up in Bluebell Audio would run you one
up if you asked him??)

If you are well-enough disciplined, there are some speaker (2 pairs)
switches that you could use in reverse (I think I have one here you
would be welcome to), but I would rather use a 'patchbox' (permissible
use here?) and switch by means of pulling jack plugs in this instance...

Amplifier switching
 

On Sun, 28 Oct 2007 14:44:10 +0000, Rob
wrote:

I've got two amplifiers and I'd like to switch between them. At the
moment I'm plugging/unplugging at the speakers. For reasons of cable
management, convenience and neatness I'd like to use a switch. QED did
one a while ago but it's discontinued, and replaced with a wall switch
which is too 'embedded' for my liking, and pricey.

I was having a look in Wickes for a suitable switch, and it looks as
though a four gang light switch would do it (8 wires in, four wires
out), but this has four switches.

Ideally I'd like one switch - amplifier A, or amplifier B.


For several reasons, can I persuade you to make up a little box with
banana plugs and sockets?

Help: Where to buy Magnepans in Europe
 

Hello,

I would like to buy a pair of Magnepan speakers -- eirther the MG
12/QR or the MG 1.6 -- and am looking for a dealer in Germany or near
to Germany, if possible. Does anyone know of a European dealership
for Magnepan?

Thanks,
Rich

Amplifier switching
 

Rob wrote:
I've got two amplifiers and I'd like to switch between them. At the
moment I'm plugging/unplugging at the speakers. For reasons of cable
management, convenience and neatness I'd like to use a switch. QED did
one a while ago but it's discontinued, and replaced with a wall switch
which is too 'embedded' for my liking, and pricey.

I was having a look in Wickes for a suitable switch, and it looks as
though a four gang light switch would do it (8 wires in, four wires
out), but this has four switches.

Ideally I'd like one switch - amplifier A, or amplifier B.

Any ideas?

Thanks, Rob

I used a couple of 12v DPDT relays powered by an old psu from a cordless
phone.
One amp has a switched mains-out socket on the back; the psu connected
into that.
That then was the master amp so when it was on, the speakers were switched
to it, and when it was off, the speakers were switched to the other amp.

If neither amp has a switched mains outlet, you could use an 'intelligent'
mains extension block with one amp connected to the master socket.

--
Eiron.

Amplifier switching
 

"Rob" wrote in message
...
I've got two amplifiers and I'd like to switch between them. At the
moment I'm plugging/unplugging at the speakers. For reasons of cable
management, convenience and neatness I'd like to use a switch. QED did
one a while ago but it's discontinued, and replaced with a wall switch
which is too 'embedded' for my liking, and pricey.

I was having a look in Wickes for a suitable switch, and it looks as
though a four gang light switch would do it (8 wires in, four wires
out), but this has four switches.

Ideally I'd like one switch - amplifier A, or amplifier B.

Any ideas?

Thanks, Rob


Maplin JK30H @ £3 each. You only need to switch the live side of the
speaker feed - the ground sides can stay connected in parallel
throughout.

RS Components 317-847 @ £13.19+VAT each. Same comment as above
RS Components 266-2234@ £17.25+VAT each. 4-pole double throw centre
off - just what you need!

www.maplin.co.uk
rswww.com


--
Woody

harrogate three at ntlworld dot com

Amplifier switching
 

Woody wrote:

Maplin JK30H @ £3 each. You only need to switch the live side of the
speaker feed - the ground sides can stay connected in parallel
throughout.


Though the OP should check (with a DVM) before doing this, that that
negative speaker outlets of *both* amplifiers concerned are actually
internally connected to ground. Ye don't want to upset a
bridge-tied-load amp, if ye have one of those in your setup ...

http://en.wikipedia.org/wiki/Bridge-tied_load

--
Adrian C

Amplifier switching
 

In article ,
Keith G wrote:
The important thing in this scenario Rob is to be sure you have a *break
before make* switch and preferably one which places the 'other' amplifer
under a load when it's switched away from. in a both amps *on*
situation. (I bet Fekki Norsaam up in Bluebell Audio would run you one
up if you asked him??)

Eh? You must be thinking of one of your strange valve amps - solid state
jobbies shouldn't be in the least concerned about running with no load.

--
*There are 3 kinds of people: those who can count & those who can't.

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

Amplifier switching
 

"Dave Plowman (News)" wrote in message
...
In article ,
Keith G wrote:
The important thing in this scenario Rob is to be sure you have a
*break
before make* switch and preferably one which places the 'other'
amplifer
under a load when it's switched away from. in a both amps *on*
situation. (I bet Fekki Norsaam up in Bluebell Audio would run you
one
up if you asked him??)

Eh? You must be thinking of one of your strange valve amps - solid
state
jobbies shouldn't be in the least concerned about running with no
load.



No, I was thinking of Rob's strange valve amps....




--
*There are 3 kinds of people: those who can count & those who can't.

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

Amplifier switching
 

Keith G wrote:
"Rob" wrote in message
...
I've got two amplifiers and I'd like to switch between them. At the
moment I'm plugging/unplugging at the speakers. For reasons of cable
management, convenience and neatness I'd like to use a switch. QED did
one a while ago but it's discontinued, and replaced with a wall switch
which is too 'embedded' for my liking, and pricey.

I was having a look in Wickes for a suitable switch, and it looks as
though a four gang light switch would do it (8 wires in, four wires
out), but this has four switches.

Ideally I'd like one switch - amplifier A, or amplifier B.

Any ideas?

Thanks, Rob


The important thing in this scenario Rob is to be sure you have a *break
before make* switch and preferably one which places the 'other' amplifer
under a load when it's switched away from. in a both amps *on*
situation. (I bet Fekki Norsaam up in Bluebell Audio would run you one
up if you asked him??)


Yep, that'd be the belt and braces way, and have the advantage of being
able to keep both switched on. Bluebell site looks good - but why no
kits? For now, I'll try the disciplined approach ...

If you are well-enough disciplined, there are some speaker (2 pairs)
switches that you could use in reverse (I think I have one here you
would be welcome to),

Hadn't thought of that; I can easily pop into Maplins, thanks for the offer.

but I would rather use a 'patchbox' (permissible
use here?) and switch by means of pulling jack plugs in this instance...


Yes, you mentioned that when I last asked about the 'safe to run a valve
amp under no load'. And I've been sort of happy just plugging/unplugging
at the speakers. But now is the time for a little hifi housekeeping, and
tidy it all up a little.

Amplifier switching
 

Laurence Payne wrote:
On Sun, 28 Oct 2007 14:44:10 +0000, Rob
wrote:

I've got two amplifiers and I'd like to switch between them. At the
moment I'm plugging/unplugging at the speakers. For reasons of cable
management, convenience and neatness I'd like to use a switch. QED did
one a while ago but it's discontinued, and replaced with a wall switch
which is too 'embedded' for my liking, and pricey.

I was having a look in Wickes for a suitable switch, and it looks as
though a four gang light switch would do it (8 wires in, four wires
out), but this has four switches.

Ideally I'd like one switch - amplifier A, or amplifier B.


For several reasons, can I persuade you to make up a little box with
banana plugs and sockets?

I suspect your main reason is the possibility that I'd run a valve amp
into open circuit, and also, possibly, my competence at wiring anything
up in the first place. Good points, noted.

Amplifier switching
 

Eiron wrote:
Rob wrote:
I've got two amplifiers and I'd like to switch between them. At the
moment I'm plugging/unplugging at the speakers. For reasons of cable
management, convenience and neatness I'd like to use a switch. QED did
one a while ago but it's discontinued, and replaced with a wall switch
which is too 'embedded' for my liking, and pricey.

I was having a look in Wickes for a suitable switch, and it looks as
though a four gang light switch would do it (8 wires in, four wires
out), but this has four switches.

Ideally I'd like one switch - amplifier A, or amplifier B.

Any ideas?

Thanks, Rob

I used a couple of 12v DPDT relays powered by an old psu from a cordless
phone.
One amp has a switched mains-out socket on the back; the psu connected
into that.
That then was the master amp so when it was on, the speakers were switched
to it, and when it was off, the speakers were switched to the other amp.

If neither amp has a switched mains outlet, you could use an 'intelligent'
mains extension block with one amp connected to the master socket.


Interesting, thanks. An issue here is that the valve amp is supposed to
be 'soft started' - one switch wait 30s, then the main switch. And it
would still mean running two sets of wires to the speakers I think?

Amplifier switching
 

Adrian C wrote:
Woody wrote:

Maplin JK30H @ £3 each. You only need to switch the live side of the
speaker feed - the ground sides can stay connected in parallel
throughout.


Though the OP should check (with a DVM) before doing this, that that
negative speaker outlets of *both* amplifiers concerned are actually
internally connected to ground. Ye don't want to upset a
bridge-tied-load amp, if ye have one of those in your setup ...

http://en.wikipedia.org/wiki/Bridge-tied_load


Thanks both, and Woody in particular for those links.

Just out of curiosity, why has it always been the case that four wires
run to speakers, when three would do (link the ground on a stereo pair)?

Amplifier switching
 

Owain wrote:
Rob wrote:
I've got two amplifiers and I'd like to switch between them. At the
moment I'm plugging/unplugging at the speakers. For reasons of cable
management, convenience and neatness I'd like to use a switch. QED did
one a while ago but it's discontinued, and replaced with a wall switch
which is too 'embedded' for my liking, and pricey.
I was having a look in Wickes for a suitable switch, and it looks as
though a four gang light switch would do it (8 wires in, four wires
out), but this has four switches.
Ideally I'd like one switch - amplifier A, or amplifier B.
Any ideas?

You need a 4pole double-throw [changeover] switch (4PDT) which you can
probably get from Maplin, FH08J is 5A at 12V so okay for low power
applications.

Bigger switches have tags which take either soldered wires, or blades
for crimp terminals (which you can also get from Maplin).

Try www.rswww.com part nos 274-0441, 320-972, 316-995, or 266-2212,
ratings 3 to 20A

Add some terminal strip for the speaker wires, and encase the lot in a
small plastic case (also from Maplin)

Owain


Thanks muchly. Plenty to go on here - thanks to everyone.

Amplifier switching
 

On Mon, 29 Oct 2007 08:36:41 +0000, Rob
wrote:

Adrian C wrote:
Woody wrote:

Maplin JK30H @ £3 each. You only need to switch the live side of the
speaker feed - the ground sides can stay connected in parallel
throughout.


Though the OP should check (with a DVM) before doing this, that that
negative speaker outlets of *both* amplifiers concerned are actually
internally connected to ground. Ye don't want to upset a
bridge-tied-load amp, if ye have one of those in your setup ...

http://en.wikipedia.org/wiki/Bridge-tied_load


Thanks both, and Woody in particular for those links.

Just out of curiosity, why has it always been the case that four wires
run to speakers, when three would do (link the ground on a stereo pair)?

Cos your speakers stand ten feet apart. Kinda hard to run a single
ground wire to both of those.

d

--
Pearce Consulting
http://www.pearce.uk.com

Amplifier switching
 

In article , Rob
wrote:


Just out of curiosity, why has it always been the case that four wires
run to speakers, when three would do (link the ground on a stereo pair)?

The two speakers will normally be placed well apart, so if using just one
'ground' lead you'd have to run it to one of them, and then to the other.
This would mean that the lengths of ground cables for each differ.

A) The main result would be a difference in cable resistance for the two
speakers, possibly causing an imbalanced change in frequency response.

B) Unless you ran both 'live' cables along the same path, one speaker
connection would have a very wide spacing between its live and ground. The
result would be very high inductance. Again possibly producing a
significant difference in frequency response for the two channels. Might
also make RF pickup a problem.

C) If you *did* run the 'live' wires together then this would mean the
'live' to one speaker would be longer than the other - making effect (A)
worse.

D) Even if you used a symmetric 'Y' shape of cable for the ground to try
and avoid some of the above, using a common ground connection increases the
level of crosstalk as the common resistance will cross-connect the signals
to some extent. Aso, (C) would increase EM crosstalk.

Should I go on?... :-)

Basically, it isn't a good idea to try and skimp by using one ground cable
for the two speakers. Probably saves almost no money, and can cause all
sorts of problems. Although the problems may be small enough that it can be
done if there is no easy alternative.

Best to use distinct cables for the two speakers, have them of similar
lengths, and run them well clear of each other.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.audiomisc.co.uk/index.html
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html

Amplifier switching
 

In article ,
Rob wrote:
Just out of curiosity, why has it always been the case that four wires
run to speakers, when three would do (link the ground on a stereo pair)?

If it were easier wiring wise to do this then no reason why not. But in
the majority of cases the speaker wires go off in opposite directions from
the amp.

--
*Modulation in all things *

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

Amplifier switching
 

On Mon, 29 Oct 2007 08:36:41 +0000, Rob
wrote:

Just out of curiosity, why has it always been the case that four wires
run to speakers, when three would do (link the ground on a stereo pair)?

As on the face of it this is such a stupid question, perhaps he's
talking about bi-amping or bi-wiring?

Amplifier switching
 

"Rob" wrote in message
...

Just out of curiosity, why has it always been the case that four wires run
to speakers, when three would do (link the ground on a stereo pair)?

The alternative would be a 3-wire system. The common wire would have to have
twice the copper per unit length. In general, the savings in terms of copper
and wire would be negligible.

If you had a typical bookshelf system with the amp or receiver in the
middle, and a speaker on each side, I can see where a 3-wire system would
make the wires longer, than separate grounds for each channel.

Amplifier switching
 

Laurence Payne wrote:
On Mon, 29 Oct 2007 08:36:41 +0000, Rob
wrote:

Just out of curiosity, why has it always been the case that four wires
run to speakers, when three would do (link the ground on a stereo pair)?

As on the face of it this is such a stupid question, perhaps he's
talking about bi-amping or bi-wiring?

Nope, no bi-anything - that'd be eight cables. As you face it, it
remains stupid.

Amplifier switching
 

Dave Plowman (News) wrote:
In article ,
Rob wrote:
Just out of curiosity, why has it always been the case that four wires
run to speakers, when three would do (link the ground on a stereo pair)?

If it were easier wiring wise to do this then no reason why not. But in
the majority of cases the speaker wires go off in opposite directions from
the amp.


Yes, I take that point. In my case the amplifier is to the left of two
speakers so a small wire saving is possible. With deference to Jim's
reply, best play safe with separate ground wires.

Amplifier switching
 

On Mon, 29 Oct 2007 18:01:04 +0000, Rob
wrote:

Just out of curiosity, why has it always been the case that four wires
run to speakers, when three would do (link the ground on a stereo pair)?

As on the face of it this is such a stupid question, perhaps he's
talking about bi-amping or bi-wiring?

Nope, no bi-anything - that'd be eight cables. As you face it, it
remains stupid.

How many wires in a cable?

Amplifier switching
 

On Mon, 29 Oct 2007 18:07:50 +0000, Laurence Payne
NOSPAMlpayne1ATdsl.pipex.com wrote:

On Mon, 29 Oct 2007 18:01:04 +0000, Rob
wrote:

Just out of curiosity, why has it always been the case that four wires
run to speakers, when three would do (link the ground on a stereo pair)?

As on the face of it this is such a stupid question, perhaps he's
talking about bi-amping or bi-wiring?

Nope, no bi-anything - that'd be eight cables. As you face it, it
remains stupid.

How many wires in a cable?

Hang on. I've heard this one...

d

--
Pearce Consulting
http://www.pearce.uk.com

Amplifier switching
 

"Laurence Payne" NOSPAMlpayne1ATdsl.pipex.com wrote in message
...
On Mon, 29 Oct 2007 18:01:04 +0000, Rob
wrote:

Just out of curiosity, why has it always been the case that four
wires
run to speakers, when three would do (link the ground on a stereo
pair)?

As on the face of it this is such a stupid question, perhaps he's
talking about bi-amping or bi-wiring?

Nope, no bi-anything - that'd be eight cables. As you face it, it
remains stupid.

How many wires in a cable?


No idea, but there's 10 cables in a nautical mile....