Actually, the OP wants 56V p-p to each 4 ohm speaker which is 100W that is too much for one LM3886 amp. The applications note shows two amps in parallel (with low value series resistors at their outputs) then the power into 4 ohms is about 110W.
I believe we are having a problem in semantics. Exactly what you mean by getting the "maximum power out of each"?
If the amp is putting out it's maximum power than that is all it can do. With proper series-parallel connection of the speakers, they will have the combined equivalent impedance for which the amplifier delivers its maximum power. But of course that power will divided by the number of speakers. What more could you expect? You can't put more total power into the speakers than an amp can deliver. For more power you need to go to more amplifiers.
I still don't understand why you're so dead-set against simply wiring your speaker array in series-parallel.
OK, forget speakers. Let's talk light bulbs instead. Let's say you're working for some crazy guy who wants you to wire up 16 100-watt lights bulbs to that they all burn at maximum brightness. (This is in the country of Freedonia, where the standard household current is 100 volts, for simplicity's sake.) But for some strange reason, he insists that you cannot just wire them in parallel like you'd normally do.
So you come up with the following plan:
**broken link removed**
Of course, the crazy guy has also supplied you with the 400 volts necessary to run four bulbs in series.
The point is, do you see that each bulb in this array burns with the proper voltage and current, and gets its maximum allowable power (100 watts)?
So series-parallel will work.
(By the way, to the O.P., you do mean "linear" speaker system, correct? I still don't know what that is; guess I'll have to look it up.)
A lot of the context is just plain wrong, I would not know where to start editing.
Take Carl's suggestion of using an IC for each speaker. The delay (or phase shift) through the IC will not be a problem. You will need one big power supply!
Take Carl's suggestion of using an IC for each speaker. The delay (or phase shift) through the IC will not be a problem. You will need one big power supply!
It is obvious that for an output of 68W into each 4 ohm speaker then each speaker needs its own LM3886 amplifier powered from a 56VDC or plus and minus 28VDC supply. Forget about series-parallel or a transformer.QUOTE]
Yea, Thats right.
With a 60VDC supply then the total of ten amplifiers is 850W which is too high for them.
For a continuous output of 680W then the power transformer must be huge and rated for about 1244VA.
Yes, VA is volt-amps. (VAR is volt-amps reactive). Transformers are rated in VA because they are limited by the current they can deliver (due to internal I²R heating from the winding resistance), not the power output. For example if the load was totally reactive you could have high current from the transformer but no power. If the load is pure resistive than volt-amps out equals watts.Sorry but What "1244VA" does mean? Is it Volt-Ampere or VAR? how to interpret it for a 60V transformer? Is it voltage x current?....
Don't you know that a 60V transformer produces rectified and filtered 83VDC, not 60VDC. 83VDC is much too high for an LM3886 that drives 4 ohms. You need a 41V transformer which will produce rectified and filtered 56VDC. It must have a current rating of 22.2A if the amplifiers blast 68W each continuously.
In addition to the 680W to the speakers, the amplifiers heat with 560W. The transformer must also supply this power.22.2A?But Why? I was thinking of 13 to 14A...
I was going to chide "Dr. Power", who seems hell-bent on putting all his speakers in parallel and burning out his amplifiers, until it occurred to me: I don't really know what happens when one puts two or more amplifiers in parallel with each other.
This ASS-U-MEs, of course, that the amplifiers are designed for this usage (bridge-able, I guess you could say). And to reduce confusion in this discussion, let's limit this to transistor amplifiers without output transformers (in other words, 99% of amps found today).
What happens to the total impedance when amplifiers are put in parallel? Both from the point of view of the amplifiers and their loads (i.e., loudspeakers). Do the impedances reduce the same way resistances in parallel do?
In other words, could "Dr. Power" actually get away with, say, putting 10 LM3886s in parallel and running 10 4-ohm speakers also in parallel, for a total load of 0.4Ω, as per the title of this thread?
Or is he just going to produce a lot of expensive smoke this way? (My money would be on this outcome.)
Inquiring minds want to know ...
To a certain extent, and with correctly designed circuits, you 'can' parallel identical amps.
However - what would be the point?. If you've got ten speakers, and ten amps, then simply feed each speaker from it's own amp - which will be at least (and probably more) ten times as reliable.
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