Hi everyone.
I have been fooling around with a pair of ACAs and I'm not sure if I understand what is going on as I change their mode of operation.
As i understand it, in the standard mode it is a single ended amp with one output terminal at ground potential and the signal applied to the other speaker terminal. This signal varies from zero volts to some positive value but never goes negative. Since the amplifier inverts the signal, the positive speaker terminal is the one that is grounded and the negative terminal gets the signal.
Parallel mono is the same situation with both channels acting the same way while bridged mono inverts the signal to the other channel and floats the signal with no ground reference.
So far so good, but...
Doesn't this mean that in standard mode the speaker cone is always on one side of "zero"? With no signal the cone is at rest in the center of its travel range. Once a positive signal is applied to the negative terminal the cone will move backwards into its suspension. When will the cone ever move past the at rest position?
In balanced mode I think that the cone will vibrate about the zero, 'at rest' position. In SE mode, isn't all of the vibration on one side of zero? Would this apply to SE amps in general, including transformer coupled tube amps?
On my LaScalas the ACA amps sound MUCH better in balanced mode than parallel mode and I don't think that it's the extra voltage swing that is the difference.
Help! I want to understand and I'm not sure that I do.
Pete
I have been fooling around with a pair of ACAs and I'm not sure if I understand what is going on as I change their mode of operation.
As i understand it, in the standard mode it is a single ended amp with one output terminal at ground potential and the signal applied to the other speaker terminal. This signal varies from zero volts to some positive value but never goes negative. Since the amplifier inverts the signal, the positive speaker terminal is the one that is grounded and the negative terminal gets the signal.
Parallel mono is the same situation with both channels acting the same way while bridged mono inverts the signal to the other channel and floats the signal with no ground reference.
So far so good, but...
Doesn't this mean that in standard mode the speaker cone is always on one side of "zero"? With no signal the cone is at rest in the center of its travel range. Once a positive signal is applied to the negative terminal the cone will move backwards into its suspension. When will the cone ever move past the at rest position?
In balanced mode I think that the cone will vibrate about the zero, 'at rest' position. In SE mode, isn't all of the vibration on one side of zero? Would this apply to SE amps in general, including transformer coupled tube amps?
On my LaScalas the ACA amps sound MUCH better in balanced mode than parallel mode and I don't think that it's the extra voltage swing that is the difference.
Help! I want to understand and I'm not sure that I do.
Pete
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Don't over think it. As the output is AC coupled, the DC values are not relevant. Some single ended amplifiers invert the phase of the signal for various reasons. When they do they will routinely designate output terminals to deliver correct absolute phase to the speaker. The speaker itself does not know about this...
