Stereo 4x12 and stereo amp questions

lol, thanks for the replies guys. I haven't had a chance to re-test my left/right panning that I've experienced before. But at this point, I'm just gonna chalk it up to a momentary, complete lapse of sanity. That happens, right?

I'm gonna go with my original plan and rewire the cab to two separate circuits.

And yes, I don't see any evidence anywhere stating that running the amp on just one channel causes damage. I'm not worried about it.
 
Lt. Bob said:
of course you're not making anything up ......... you're one of the good guys here.

I did go and look and it's actually not that clear.

Although it says you want to hook up both sides (amps) to a cab 8 ohms or higher to avoid amp failure .... above that it only says that if you don't connect both sides to a stereo cab half the speakers won't work ... but no mention of damage.

Also above THAT it says that "All Line 6 amplifiers (with the exception of the Spider valve series) are safe to run without any speaker load connected" ...... so personally I'm reading that as you can run one side with no load but don't hook them up to less than 8 ohms.

But it's pretty unclear to tell the truth. You could interpret it either way.







However, if I had a line 6 amp one of my desires would be to blow it up so maybe I'm not the best to ask!
:D
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Yeah, their info can be vague, but its been covered in the user forums there. I love my Spider. IF I was playing full-on rock loud, it would not be the best choice, but for doing Beatles music with acoustic and electric guitars and keyboards, and for recording, it's great.
 
Lt. Bob said:
think about it .... how could 2 speakers work when you plug one amp in, and then 2 different speakers work instead when you plug the other amp in using the same jack?

not possible.

Also ..... either you have that circuit drawn wrong or all four speakers work when you plug into either of those jacks.
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There is a possible way, not that I'd expect it from a guitar amp and cab. If one amp is designed for high frequencies and the other for low frequencies and a crossover is designed into the circuit.

With the circuit diagram given, showing no crossover, it isn't possible.

Like I said, I've never seen a guitar amp like that; but that doesn't mean some manufacturer didn't decide to do it. I have seen a bass cab including a horn with a crossover in it. But I'm not sure of the point if all four speakers are the same. I really don't see the point in two outputs, one high, one low, going into a cab where both jacks are parallel. The crossover would work and seperate them, but you lose power compared to two separate input jacks.

Whatever the case I suspect someone rewired this amp to mono and it didn't come from the factory this way. When I want stereo for guitar effects I use two amps across the room from each other.
 
Here's the amp outputs, by the way. There is no mono out. It's purely stereo.

2012-07-21113238.jpg
 
http://acapella.harmony-central.com/attachment.php?attachmentid=189489&d=1136990201
That ^ is the standard Marshall wiring for a 4 x12 giving 2 8Ohm speakers (2 per side) and 4 by 16Ohms or 4 by 4 Ohms.

Now, you can use exactly the same setup to give 2 x 2stereo at 4 Ohms and and a 4by 8Ohm cab if you load it with 8R drivers BUT! Note that the other resultant impedance is TWO Ohms!! Certain, instant death to most solid state amps.

I would also question the wisdom of leaving even a solid state amp unterminated. Sure, it is ok 99% of the time IF the amp channel is not driven but if it is, and especially if it is OVERdriven, the Zobel network can burn out and cause transistor failure.

A load of 100Ohms at 10 watts will keep it supersafe.

Dave.
 
Well, I wired up the cab yesterday, and it sounds great! Two isolated 2x12 circuits, in an X-pattern. I can just play through one input if I don't want to be so loud. With both operational, I damn near blew the walls out of my bedroom. This setup works out very well. I'm confident I can provide more than ample volume for live shows.

Now in a few months, when I move, I plan on putting a band together out of my solo project, so I'll finally get to use my rig in a band setting.
 
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