2 amps one cab...help!

[papa-seano]

Hi guys.
I own a 2266 Vm and am currently looking for a second amp ( maybe DSL 50 ) to partner it.
I love the sound of the VM on the higher range but wanted to even it out with a bit more clarity by adding a second amp running a little cleaner.

I have a Marshall AX 4x12 cab with 25 watt greenys and its got a mono input on the rear.

Is there any way without modding the cab or getting another cab that I can run both amps through the same cab. No switching etc..just both in and on?
EG.. A-B boxes etc?????

I havnt a clue. If any one could help with any ideas then i'd be grateful. Cheers.

 

[demonufo]

Hi guys.
I own a 2266 Vm and am currently looking for a second amp ( maybe DSL 50 ) to partner it.
I love the sound of the VM on the higher range but wanted to even it out with a bit more clarity by adding a second amp running a little cleaner.

I have a Marshall AX 4x12 cab with 25 watt greenys and its got a mono input on the rear.

Is there any way without modding the cab or getting another cab that I can run both amps through the same cab. No switching etc..just both in and on?
EG.. A-B boxes etc?????

I havnt a clue. If any one could help with any ideas then i'd be grateful. Cheers.

Nope. Not without splitting the cab with two jacks and setting them up as two 2X12's. But you're asking for trouble using 50w heads with only 50w handling of speakers. Not only that, but because the amps are going to have different signals and responses coming out, unless you isolate the internals of the cab (split it into two airtight halves) you're gonna get some odd interactions and some real crappy sounds coming out.

Whichever way you look at this issue, there isn't really a good solution I'm afraid.

 

[Bieling3]

Hrmmm... have to disagree with, "because the amps are going to have different signals and responses coming out, unless you isolate the internals of the cab (split it into two airtight halves) you're gonna get some odd interactions and some real crappy sounds coming out."

[ame=http://www.youtube.com/watch?v=Jp5Nt5X0cz0]YouTube - Marshall SL-X Vs Marshall JCM800 2203KK[/ame]

Might not work everytime, but it is possible.

 

[gtrman]

If you want to use all 4 speakers with both amps you need something like this:

Tonebone Headbone VT valve tube amp head switcher - introduction

It's pricy but i believe this is the best solution if you can afford it.

 

[Moose Coghill]

If you want to use all 4 speakers with both amps you need something like this:

Tonebone Headbone VT valve tube amp head switcher - introduction

It's pricy but i believe this is the best solution if you can afford it.

"For years I've been trying to combine all of my favorite tones on stage without carrying a ton of amps and cabinets on stage. The Headbone helps me get there. Thank God I found it. I only wish I had it years ago... I love my Headbone!" ~ Mark Tremonti

Wow... so I guess it is done. The switching capability interests me. Thanks for the link gtrman!

 

[Trick]

http://www.marshallforum.com/marshall-amps/20865-stereo-help-needed.html

 

[papa-seano]

Hrmmm... have to disagree with, "because the amps are going to have different signals and responses coming out, unless you isolate the internals of the cab (split it into two airtight halves) you're gonna get some odd interactions and some real crappy sounds coming out."

YouTube - Marshall SL-X Vs Marshall JCM800 2203KK

Might not work everytime, but it is possible.

So how is both the amps working together? Is this coming through the cab they are sat on? Sounds pretty good to me.

 

[demonufo]

Hrmmm... have to disagree with, "because the amps are going to have different signals and responses coming out, unless you isolate the internals of the cab (split it into two airtight halves) you're gonna get some odd interactions and some real crappy sounds coming out."

YouTube - Marshall SL-X Vs Marshall JCM800 2203KK

Might not work everytime, but it is possible.

Yes it is possible, but VERY unlikely to work. Even two near identical amps with different filtering and different bias are going to behave very differently with each pair of speakers, which will start to fight with each other.

It's a pretty daft thing to try without two seperate cabs. Unless you properly split that cab internally.

Even if you could get it to sound reasonable, I can absolutely guarantee that it will sound better and more focussed with a properly split cab.

 

[demonufo]

If you want to use all 4 speakers with both amps you need something like this:

Tonebone Headbone VT valve tube amp head switcher - introduction

It's pricy but i believe this is the best solution if you can afford it.

That's no good at all. The original poster wants to use both amps together at the same time. The Headbone simply switches BETWEEN two amps, and applies a load to the amp not in use.

 

[Moose Coghill]

Oh - yeah, you're right... I just got caught up in being able to share one cabinet with two amps. Thought it was a cool option. I'd be afraid of the load failing though.

For what he wants to do, he just needs two separate rigs and an ABY box.

 

[Trick]

Another thing to consider would be their "phase relation" I tried to use a 1985 JCM800 2204 with a 2002 JCM2000 DSL50 and had an phase hum, the two amps were "outta phase" and hummed like crazy. I'm sure a tech could describe what I'm talking about better than I, but I was bummed that wouldn't work, so I had to sell my DSL and buy another 2204. Damn it! lol!

 

[papa-seano]

No worries. Thanks for the comments men. Very helpful.
Yep the tonebone would not help in this situation but a very handy tool.
Two cabs it is then..and yep i've heard about two amps being out of phase.

I'll have a think.
Cheers.

 

[Bieling3]

Another thing to consider would be their "phase relation" I tried to use a 1985 JCM800 2204 with a 2002 JCM2000 DSL50 and had an phase hum, the two amps were "outta phase" and hummed like crazy. I'm sure a tech could describe what I'm talking about better than I, but I was bummed that wouldn't work, so I had to sell my DSL and buy another 2204. Damn it! lol!

That's what a 9 volt battery is for. To bad you sold you head because you didn't know. Really, despite previous objections, there shouldn't be too much of an issue running two heads into a stereo cab. I never had a problem with it when I ran my valveking and 6505 into the same 1960a.

The video I referred to above kinda nixs the notion that such an operation will inherently sound bad.

 

[Trick]

That's what a 9 volt battery is for. To bad you sold you head because you didn't know. Really, despite previous objections, there shouldn't be too much of an issue running two heads into a stereo cab. I never had a problem with it when I ran my valveking and 6505 into the same 1960a.

The video I referred to above kinda nixs the notion that such an operation will inherently sound bad.

Uh...hmm a 9v battery had nothing to do with it, Yes in a effect ground loop yes, But I'm talking Dry-no effects-try it you'll see. I use two heads/one cab, but the heads match, The prob was the DSL and the old JCM have two different type of circuits that had a phase relation issue. All this talk about needing two cabs is incorrect, a STEREO cab is all you need. Switch it correctly, set the ohm selector correctly and everything should be cool! It's not Rocket Science.

 

[Wycked Lester]

i used to run 2 5150 1/2 stacks in stereo, and I always had to plug the heads in to 2 seperate circuts of the fuse box or I would get a real bad hum.

 

[Bieling3]

Uh...hmm a 9v battery had nothing to do with it

Yes, yes it does. If you are having a phase issue you can use a 9 volt battery as described in the link to move the cones and get them in phase.

Yes in a effect ground loop yes, But I'm talking Dry-no effects-try it you'll see.

What? It does not follow.

All this talk about needing two cabs is incorrect, a STEREO cab is all you need. Switch it correctly, set the ohm selector correctly and everything should be cool! It's not Rocket Science.

Um, that's what I'm saying.

 

[demonufo]

Well, I'm sorry, but I respectfully disagree with all of this, having worked on loudspeaker designs years back (admittedly as a DIY-er, but took my hi-fi very seriously back then, and did an awful lot of reading up on the hows, whys, and why nots). Two different amps will produce very different bass response whether they are in phase or not. They will produce stronger notes at different frequencies which will fight against the other pair of speakers regardless of the phase too.
It will not necessarily sound awful like this, but it won't sound correct. It may be good enough to your ears, but it will sound a whole lot better with the speaker cabinet correctly split and chambered as if they were two cabs. In fact, unless the seperation is really solidly braced, there will STILL be a negative interaction between the two halves of the cabinet if those amps are cranked to a certain degree, because of the wood flexing, which will push/pull the cones due to the air pressure exerted.

Then (in a cab that isn't seperated) there is the issue of unless both amps are set at roughly equal volumes, there will be excessive amounts of force being presented to the pair of speakers that are quieter, effectively making them work like a passive radiator, when they want to be a free-moving energised piston. This will have serious repercussions to the quality and clarity of the sound produced by them, so unbalanced perceived volume from each half of the cab would be a really bad idea. Which is usually the way dual amp stereo setups tend to end up being.


If anybody was to really persevere with this silly idea, the best way would be to seperate both halves of the cab, AND make one or both halves open backed, which would get over these problems. But personally, I don't like the sound or the inflexibilty of open backed cabs, since they only work well in corners and close to walls.

For those guys that do have two amps running into a stereo cab, then you'll really need to actually try proper seperation to appreciate the difference, rather than just claim "Well it works fine for me."

I'm not knocking anybody that does do this, simply trying to get you all to understand that it is far from ideal, and whether you can hear it or not, is more likely to be improved upon vastly by doing it properly.

 

[Wycked Lester]

Well, I'm sorry, but I respectfully disagree with all of this, having worked on loudspeaker designs years back (admittedly as a DIY-er, but took my hi-fi very seriously back then, and did an awful lot of reading up on the hows, whys, and why nots). Two different amps will produce very different bass response whether they are in phase or not. They will produce stronger notes at different frequencies which will fight against the other pair of speakers regardless of the phase too.
It will not necessarily sound awful like this, but it won't sound correct. It may be good enough to your ears, but it will sound a whole lot better with the speaker cabinet correctly split and chambered as if they were two cabs. In fact, unless the seperation is really solidly braced, there will STILL be a negative interaction between the two halves of the cabinet if those amps are cranked to a certain degree, because of the wood flexing, which will push/pull the cones due to the air pressure exerted.

Then (in a cab that isn't seperated) there is the issue of unless both amps are set at roughly equal volumes, there will be excessive amounts of force being presented to the pair of speakers that are quieter, effectively making them work like a passive radiator, when they want to be a free-moving energised piston. This will have serious repercussions to the quality and clarity of the sound produced by them, so unbalanced perceived volume from each half of the cab would be a really bad idea. Which is usually the way dual amp stereo setups tend to end up being.


If anybody was to really persevere with this silly idea, the best way would be to seperate both halves of the cab, AND make one or both halves open backed, which would get over these problems. But personally, I don't like the sound or the inflexibilty of open backed cabs, since they only work well in corners and close to walls.

For those guys that do have two amps running into a stereo cab, then you'll really need to actually try proper seperation to appreciate the difference, rather than just claim "Well it works fine for me."

I'm not knocking anybody that does do this, simply trying to get you all to understand that it is far from ideal, and whether you can hear it or not, is more likely to be improved upon vastly by doing it properly.

I'll let eric johnson know.

 

[diesect20022000]

"For years I've been trying to combine all of my favorite tones on stage without carrying a ton of amps and cabinets on stage. The Headbone helps me get there. Thank God I found it. I only wish I had it years ago... I love my Headbone!" ~ Mark Tremonti

Wow... so I guess it is done. The switching capability interests me. Thanks for the link gtrman!

and here i thought it was because he was a rich rockstar and has his roadies setting up all his amps now.

i know in my GW he said he uses a fender for cleans,a recto for rhythms and a two rock or something for leads and mixes the latter two at times for rhythms or something along those lines. I always read those things but, he's not one of the "players" i aspire to be other than that he's LOA-DED!

 

[cagamp1]

Bieling3, are you serious? Ha, Ha. Nobody here is talking about the speakers being in phase. The topic is the amp output signals not being in phase.

Demonufo is correct from an acoustic and sound reinforcement standpoint.

Yes Marshall made a stereo cabinet and you can hook two amps with two different signals into each side. But, it will hinder the sound quality by cancelling frequencies. It is a bad idea actually on Marshall's part. To correctly implement the stereo idea in one cab there would have to be a sealed dividing wall between the two sets of speakers.

Stereo signals, or in this case two different heads, will always sound better when connected to seperated speaker enclosures.