Hey,
I have found several answers to this question but none which are really specific enough and I wondered if anyone could help out!
I have a marshall mode four Cab and Head alongside an Orange Dual Terror.
Is there anyway possible of having both of these heads going into the cab at one time (ie via a splitter speaker cable) and then being able to switch between amp heads?
I love their tones individually but I want to be able to switch between out and out rock marshall and the warmth of the dual terror?
Please help me out! haha
nik
Could you use two splitter type boxes one for input and you'd need another one for the ouput into the cab. Don't know how practical that would be in a live setting unless there are ways to use a footswitch with them.
"It's all about stickin it to the man!"
It's a long way to the top if you want to rock n roll!
This Morley AB Y shows the idea of one guitar going to two amps. It is "either" or "both". You would use the reverse, or the box (circuitry) turned around. One line from each amp to the AB Y box and the single line to the cab. I wouldn't buy the Morley though, because you can hit the "both" switch, which can't be good. I would want to just have A or B specifically. Therefore, I would recommend one with only a choice between A or B, and not Both. See link below.
http://www.startouchpedals.com/home.html Look at the most basic which selects A or B only, therefore an AB box.
Here is another link which specifies you need an AB box, not an AB Y which allows both, and I don't think that's good.
Like a bird on the wire,
like a drunk in a midnight choir
I have tried in my way to be free.
You'll still need two if I'm not mistaken though if you have two heads and only one cab. If you have two heads and two cabs you only will need one A/B.
"It's all about stickin it to the man!"
It's a long way to the top if you want to rock n roll!
I haven't done it myself, nor seen anybody use this set up. But I referred to the one A/B that you need between 2 heads and one cab. Cnev has a point and you need 2 boxes if you are going to use one guitar into two heads. That calls for the second box or is it the first of two if you don't want to go back and forth plugging the guitar into one amp then the other.
Two heads are better than one. :shock: Oh no, whatta pun, but I mean: answerers, not amplifiers. 8) But your 2 amps are fine and you should be good to go with 2 boxes and good speaker cables from amps to the cabinet to avoid excess noise.
Stick around, join in any discussion, and let us know. :lol:
Like a bird on the wire,
like a drunk in a midnight choir
I have tried in my way to be free.
If you use any kind of switching between outputs for tube amps into a speaker, you MUST have a dummy load for the amp that's not outputting into the speaker, and the switch MUST be a "make before break" type that NEVER lets the amp be unloaded on the output even for a millisecond. Otherwise you risk frying a tube amp. When current is flowing in the windings of the output transformer and is suddenly interrupted (in either winding), the stored energy in the magnetic field generates a voltage spike like that in the ignition coil(s) of your car engine, running up into the tens of thousands of volts. It can penetrate the insulation in the transformer and can arc over at the output tube socket, in either case leaving conductive carbon tracks that can short out the amp either immediately or at some later time. Output transformers are expensive to replace. NEVER run a tube amp with the speaker unplugged, even for an instant, and don't switch the output without switching in the alternate load before the speaker's disconnected. You may get away with it for a while, but the first time may result in a silent amp.
Personally, I think the output switching is a bad idea. I'd give each amp its own speakers and switch or blend the inputs.
"A cheerful heart is good medicine."
And Rico, I agree with you! A caution is a very wise thing, if not a precaution to abort the plan? Not that I would want the asker to fry his amp or blow the speakers, but it would only take so long to have at least some degrading effect on tubes, since they don't like a change in electrical charges, or loads - change in signal environment - I honestly don't know what to call it. Also, you are quite clear in your statements about the insulation in the transformers, and I might add the possibility of damage to biasing resistors at the tube socket, where you point out that there will be arcing, if output is interrupted.
Then, I'd never have the "both" setting of an A/B Y to overload the speakers in just one cab, in case the user got hold of the wrong type of box, and stepped on the wrong switch. I note what you say about the millisecond no-load. That is as you have described, a hazard to the output transformer, and you would know more than I - though we were both on the same Firebottle (tube and tube amp issues) forum. Now I would proceed with caution or truly decide that you are correct.
You got me with the word "millisecond" and I was hoping that a switch from one amp to the other was going to make a "continuous" circuit, or load, but WOW, what about the other amp turned ON and not outputting into the speaker? :shock:
I've seen people turn on amps without connecting cabs, and even more people running combo amps with the speaker(s) momentarily disconnected, for minutes overall, while testing other set ups. I never did know how long they could get away with it. I only had one amp myself, that came to me with arcing across a power tube's connections (soldering of pins inside) and a corresponding cracked and burnt resistor - I didn't figure HOW it happened, just replaced the resistor.
Like a bird on the wire,
like a drunk in a midnight choir
I have tried in my way to be free.
This is something I learned from discussions with the old pros on the old Firebottle board. I also learned from them to build in a failsafe device into amps, like a resistor of about 20X the nominal impedance of the output bridging the jack to lower the Q of the output transformer windings to reduce the chances of harm running an amp unloaded. You can leave that running all the time with a 5W resistor or so, and will never hear the small amount of power lost in the resistor. Under some circumstances, neon lamps, spark gaps, Zeners and other devices can work.
"A cheerful heart is good medicine."
This is something I learned from discussions with the old pros on the old Firebottle board. I also learned from them to build in a failsafe device into amps, like a resistor of about 20X the nominal impedance of the output bridging the jack to lower the Q of the output transformer windings to reduce the chances of harm running an amp unloaded. You can leave that running all the time with a 5W resistor or so, and will never hear the small amount of power lost in the resistor. Under some circumstances, neon lamps, spark gaps, Zeners and other devices can work.
Oh Boy, you can say that again! :D :wink:
Like a bird on the wire,
like a drunk in a midnight choir
I have tried in my way to be free.
The easiest way I see to make this work would be to split the speakers in the cab so half of the speakers go to each amp head and then use the AB box for switching amps.
"Work hard, rock hard, eat hard, sleep hard,
grow big, wear glasses if you need 'em."
-- The Webb Wilder Credo --
The easiest way I see to make this work would be to split the speakers in the cab so half of the speakers go to each amp head and then use the AB box for switching amps.
Yes, I get it (and it's not even my question, I hope njekyll can benefit from this, obviously) TR... so what's next? We have one 1/4" input to the cab, I assume? The cab is a Marshall X 4 speakers. Would that take another jack to 2 of the speakers, and of course wire them parallel I think, to simulate or duplicate the load of 4? It'll probably be 8 ohms, most common. Of course, one would have to check - sometimes a load will be 16 ohms, I understand that, and sometimes only 4 ohms. I never have to worry about that stuff - I own an 8 ohm single 12" cab and it's easy. Goes with all my combos. :wink:
Okay, here we get the A/B from the guitar to the amps. And then each amp just goes direct with a cord, no box, to one of the input jacks on the speaker cab - except there's one input there now, until there's two?
I like it except, are we willing to accept that the user is switching between amps, and the unused amp which will not be receiving guitar input, would just be hummin' away, "blank" or amp signal only into two speakers? What about that? :D
Oh BTW, there are two different Mode Four Cabs with different impedences darn it, and we don't know which one, and there is no provision for stereo, as with some other cabs, but I don't think that will matter, I'm assuming one input for one cabinet regardless. Later: I see that either cab can be used with any Marshall amp, as-is, prior to any mods at least. And I assume it would be okay to wire the 16's parallel for 16 ohms total and the 8's in series if 16 ohms is best/ needed.
MF280A/MF280B
280 Watt, 16 Ohm, mono, 4x12†cabinet loaded with four, custom-voiced Celestion speakers; has a lowered frequency response and is 3†taller than a standard 1960 cabinet. This cabinet produces a balanced mid range and huge bottom end. Designed to compliment the MF350 head, they can be used with any head.
Loaded with 16 Ohm, 70 Watt “Vintage 30MF†Celestion/Marshall speakers
MF400A/MF400B
400 Watt, 8 Ohm, mono, 4x12†cabinet loaded with four custom-voiced Celestion speakers; has a lowered frequency response and is 3†taller than a standard 1960 cabinet. Produces massive headroom and extremely tight bass response no matter how low you tune. Designed to compliment the MF350 head, they can be used with any head.
Loaded with 8 Ohm, 100 Watt, G12-K100 Celestion/Marshall speakers
IDK since their 1960 and Vintage cabs have this: "There is a switch on the jack plate to change to mono mode. Then you can plug into either the 4 ohm input on the left (for use by itself) or the 16 ohm input on the right (for use in a stack)."
It took me awhile, but I found specs on the MF (Mode Four) 350, and we don't know if we're dealing with that exact head; but it didn't show relevant figures anyway. This sentence explains it: "It features a fully balanced, differential mode, current feedback power amp that can deliver a staggering 350 Watts into 8 Ohms."
At this point, don't bother replying to me - I'd wait to see if our new friend Nik is still trying to figure it out? We're just talking to ourselves for the last while - sorry I have calls to make and gotta go for the rest of the day to a meeting. :(
Like a bird on the wire,
like a drunk in a midnight choir
I have tried in my way to be free.
