2 heads, 1 cab

samzadgan

This may be a stupid question...tonight i'm picking up a second head...but i have 1 2x12 cab.

i don't want to run a stereo rig or anything like that...and i don't have the space for more cabs. But, i will want to use both amps (one at a time) and i'm too lazy to keep unplugging the speaker cable from one head and put it into the other, and also wouldn't want to screw up a head by turning it on and forgetting that its not plugged into speakers.

So my question is...is there some easy cheap device that allows me to always have the two heads connected to the 1 2x12 cab, and it just works based on which ever head i ON at the time?

everything i see on google is people asking about stereo rigs, so couldn't find an answer there.

wordy

Its something I've wondered about myself for a while.

Isnt there something called a Tonebone that does this?  But does it effect the tone?  I read once that it does.

ICBM

Depends if you want to do it on the fly, or just to turn on one amp or the other.

To do it properly and safely on the fly needs a fairly complex system which switches both the input and output to the amp at the same time, and puts the unused amp on a dummy load (to protect against the rare cases where an amp can be unstable with no load and no signal), and preferably mutes both amps during the changeover to stop switching spikes. Radial make switching units to do this, which seem to have a good reputation. There may be others.

To do it with just one amp turned on at once you just need a switching box - DPDT switch, two input jacks, output jack, and a dummy load to protect against turning on the wrong amp. You could probably build that for about £20 in parts, including a decent casing.

ecc83

http://www.maplin.co.uk/p/toggle-switch-4pdt-fh08j

I am averse to commoning signal earths so I would use the above switch and since the other amp is never supposed to be on I would use a simple short instead of a load. The few seconds it should take you to realize the amp is not making a noise should do it no harm.....VALVE OP stages ONLY of course! 

The switch is rated for 6A (at 125Vac ) so that is a very conservative 144W at 4 Ohms and much more for higher impedances.

Dave.

fretmeister

The Headbone does it

http://www.tonebone.com/headbone.php

samzadgan

fretmeister said:

The Headbone does it

http://www.tonebone.com/headbone.php

Looks like this one does the trick! thanks...but shit its expensive!

fastboy

I think one of the limitations of the tonebone if you read the manual is that it doesn't like switching amps if you have effects like delay on at the same time so might want to check. 

In terms of switching systems, I looked at various and whilst this is undoubtedly total overkill for what you want, the best system I could find off the shelf was the Brunetti Matrix which allowed you to switch between up to 3 heads and cabs in any combination and also having multiple FX loop's and again switching in any combination with your heads. 

Looked great but not cheap at £900

Monstronaut

Metroamp Head Master does just this. It's $279. You'd have to factor import duty and VAT onto that too.

Monstronaut

Monstronaut said:

Metroamp Head Master does just this. It's $279. You'd have to factor import duty and VAT onto that too.

Although apparently the metroamp site has been brought down by malware and all is lost so I don't know how you'd get one at the moment.

samzadgan

i was initially hoping for something like a Y cable...but thats just naive!

to be clear i don't want to switch amps whilst playing (although that would be nice). My main purpose goes like this:

Tonight i got home i want to play through my jet city...tomorrow night, i might want to play through the Marshall...or i might play through the marshall...but half way through i want to play through the jet city.

I could just unplug and plug in the cable...but it would be nice if i didn't have to...but for £250+ i think that's what i will have to do for the meantime. Down the line if i have enough space i will just get another cab with that money.

ThePrettyDamned

samzadgan;200143" said:

i was initially hoping for something like a Y cable...but thats just naive!



to be clear i don't want to switch amps whilst playing (although that would be nice). My main purpose goes like this:



Tonight i got home i want to play through my jet city...tomorrow night, i might want to play through the Marshall...or i might play through the marshall...but half way through i want to play through the jet city.



I could just unplug and plug in the cable...but it would be nice if i didn't have to...but for £250+ i think that's what i will have to do for the meantime. Down the line if i have enough space i will just get another cab with that money.

Safer, too. You'd only have yourself to blame if you unplug with the amp on if that headbone broke (no idea how it works so don't quote me on this) and it suddenly left an amp with no load...

ICBM

samzadgan said:

i was initially hoping for something like a Y cable...but thats just naive!

to be clear i don't want to switch amps whilst playing (although that would be nice). My main purpose goes like this:

Tonight i got home i want to play through my jet city...tomorrow night, i might want to play through the Marshall...or i might play through the marshall...but half way through i want to play through the jet city.

I could just unplug and plug in the cable...but it would be nice if i didn't have to...but for £250+ i think that's what i will have to do for the meantime. Down the line if i have enough space i will just get another cab with that money.

In that case what @ecc83 said is correct - you just need an A/B box which grounds the unused input. To be safest you just need to put the unused amp on standby, if you don't want to turn it fully off every time. You'll notice immediately in the event of turning on the wrong amp, because no sound will come out.

(I agree with him about not linking grounds across two amps as well, but it's unlikely to cause any harm with two modern valve amps where both speaker negative connections are almost certainly grounded anyway.)

samzadgan

ICBM said:

Depends if you want to do it on the fly, or just to turn on one amp or the other.

To do it properly and safely on the fly needs a fairly complex system which switches both the input and output to the amp at the same time, and puts the unused amp on a dummy load (to protect against the rare cases where an amp can be unstable with no load and no signal), and preferably mutes both amps during the changeover to stop switching spikes. Radial make switching units to do this, which seem to have a good reputation. There may be others.

To do it with just one amp turned on at once you just need a switching box - DPDT switch, two input jacks, output jack, and a dummy load to protect against turning on the wrong amp. You could probably build that for about £20 in parts, including a decent casing.

ecc83 said:

http://www.maplin.co.uk/p/toggle-switch-4pdt-fh08j

I am averse to commoning signal earths so I would use the above switch and since the other amp is never supposed to be on I would use a simple short instead of a load. The few seconds it should take you to realize the amp is not making a noise should do it no harm.....VALVE OP stages ONLY of course! 

The switch is rated for 6A (at 125Vac ) so that is a very conservative 144W at 4 Ohms and much more for higher impedances.

Dave.

ok that sounds exactly like what i need...but i wont be able to build anything as i have not idea about electronics...does anyone here know anywhere i can get this built?

ecc83

"(I agree with him about not linking grounds across two amps as well, but it's unlikely to cause any harm with two modern valve amps where both speaker negative connections are almost certainly grounded anyway.)"

Thanks.

Yes, I am being extremely pikky/pessimistic here because I am posting on a public forum where any fool (all PRESENT company excepted OF COURSE!) can have a dabble. That said, the 4 pole switch is only four quid and the only other downside is a bit more wire and headscratching!

Dave.

ICBM

ecc83 said:

Yes, I am being extremely pikky/pessimistic here because I am posting on a public forum where any fool (all PRESENT company excepted OF COURSE!) can have a dabble. That said, the 4 pole switch is only four quid and the only other downside is a bit more wire and headscratching!

There's also the downside of greater potential unreliability by introducing two switching points into each speaker path instead of one. Granted, not a lot greater - twice a very small number is still a very small number!

samzadgan said:

ok that sounds exactly like what i need...but i wont be able to build anything as i have not idea about electronics...does anyone here know anywhere i can get this built?

I could do it for you. I'll need something for labour as well though since I'm supposed to get paid for doing this .

Sounds like about a £40 item.

(If building from scratch I'd probably go with Dave's prefered switch, too.)

samzadgan

ok cool @ICBM..let me get back to you tomorrow...as i will know by then if i have the second head.

Gassage

Palmer do a gadget for this

http://www.palmer-germany.com/mi/en/TINO-SYSTEM-Switching-System-2-Guitar-Amplifiers-to-1-Cabinet-with-Remote-Input-PTINOS.htm

Phil_aka_Pip

That Palmer looks like a SwitchBone plus a HeadBone all in one box (less a few of the SwitchBone bells & whistles). I like the look of it

sherpa_man

do you know of a device that will let you mix both heads?

ICBM

sherpa_man said:

do you know of a device that will let you mix both heads?

No, that can't be done - not safely, anyway. Or not at full power - you could do it by dummy loading each amp and then mixing a portion of the signal with the other amp so that each didn't interact with the other much and feeding that to the speaker, but I think you would be limited to no more than about half the power from each amp, possibly less.

It's just far easier to do it with a separate speaker for each amp.