So- what if a dude was to want to set his Randall Commander head on top of his Lab Series L5 212 combo and run the both through the L5's speakers and use like an ABY box to switch between the two or even blend them?
Neither of these amps are channel switching amps so they don't have clean or dirty tones at the press of a button. I'd like to try to use the Randall for dreamy cleans and the L5 for punchy distortion but run them both through the L5's speakers so I don't have to lug another cab around.
Is this possible and relatively easy to do?
Thankie.
Chews. :cheesy:
Blending is not possible.
Switching is only easy if you turn off both amps. Otherwise you need a fairly sophisticated switching box that makes absolutely sure the first amp is disconnected before the second is connected.
Both amps connected to the same load at the same time usually ends in smoke, flames, and tears.
Quote from: ChewyNasalPrize on May 02, 2014, 01:31:42 PM
So- what if a dude was to want to set his Randall Commander head on top of his Lab Series L5 212 combo and run the both through the L5's speakers and use like an ABY box to switch between the two or even blend them?
This is trying to combine two power sources into a single load, and it's a very bad idea, very likely to damage the amps in question, valve or solid-state.
Signal combining/processing has to be done at low (Line levels), not at power output levels.
{There is only one safe way,
bridging an amp
intended for it with its two
identical amps driving opposite ends of the load in opposite directions.}
Randomly connecting amp outputs together will let the smoke out somewhere. :'( :trouble
PLUS..... you may need a dummy load that will load the output of the amp you switch out. I wouldn't do it. Easier to use an ABY on the input signal and have 2 completely separate amps.
I've always wondered if you could connect two amps to a double voice coil speaker. What do you guys think? I'm sure it's not a good idea, just not sure if it would even work (without immediate smoke).
I don't think it's a good idea either. The extra coil is just an additional winding, basically to double power handling or just alter the overall impedance (depending wther you connect the coils in series or parallel).
The way I see it, both coils expect to see identical current flow as that is what magnetizes the voice coils and subsequently causes the former (and the attached diaphgram) to move in the magnetic field introduced by the permanent magnet.
And indeed it is possible to drive such speakers from different amplifiers assuming all these amplifiers behave identically, and in practice output the very same signal.
And as is the case as well with the more generic bridged and parallel connected amplifiers the hard part is ensuring that....
If the current flow in coils is unidentical, in worst case exactly opposite in both coils, you have excitation that draws, or tries to draw, the former into different directions. Like with power supplies, the stronger magnetic field would likely be dominant in this "fight" but the coil with lower current would be robbing "power" away from the stronger one and vice versa... At best this just introduces some distortion to the cone excursion, but at worst I would imagine there would be also somekind of flyback fed to the "redundant" coil, which would then directly affect the amplifier driving it. At worst detroying it completely.
I never tried this but I don't have disposable dual voice coil speakers and amplifiers on hand either. And I'm quite sure that for the experiment they would indeed have to be disposable.
Other than that, for the sake of experiment it might be educative. Like crashing expensive cars loaded with expensive crash test dummies into other cars or various obstacles. Educative in all kinds of terms, but I'd never give my very own stuff to test it because the generic consequences are kinda predictable: The cars and the dummy will be wrecked. Results of such experiments merely reveal how.
Well put. :dbtu:
I'd just like to add that while it is fairly commonplace to connect solid state amps in bridge configuration I've yet to see a valve/tube amp that has such a facility, the reason being phase rotation in the output transformer(s).
Whatever you decide to do to "crash test" s.s. amps do not try this with valve/tube amps because the result is highly predictable and highly expensive. :'(
Those are the results I kind of expected. If I ever get rich maybe I'll try it anyway, in the name of science.
Driving a dual voice coil speaker with two separate amps (one to each ) is roughly the same as having 2 horses tied to a cart, each with a long string and not tied to each other but free to roam wherever they want, and then letting a firecracker go off nearby.
Only by sheer chance they will go the same way and pull with equal strength and at the same time, the usual result will be that they either tear the cart apart in 2 pieces and/or strangle each other.
The horses are amplifiers and the cart is the speaker.