How did you come by this knowledge ? I have been looking for details on thi s for years now. Thanks.
I do believe I saw one a long time ago. It was kinda wierd, disconnecting o ne coil lost all the low end but the other one disconnected seemed to make it a subwoofer only.
Normal woofers take advantage of the constant voltage nature of amplifiers and when they pull more current at lower frequencies it TENDS to make up fo r the fact that the radiating surface is so much smaller than the wave to b e radiated.
Actually in selecting woofers, this is why I tend to prefer the ones with a lower Re which is DC resistance. Without a shitload of equalization, how else does one squeeze out that bottom octave ?
Of course alot of wimpy amps do not like this. The whole industry makes mor e money because of the lack of a solid low octave and underbuilding (IMO) t he output stages of these amplifiers.
I've been doing a little vintage audio lately, and my pardner has this Sans ui AU-9500. I think the thing is great. Really. Iopens it up and looks at t he transformer and heat sinks and think "Hmm, what is this about 200 a chan nel ?". Nope SIXTY FIVE ! (or something like that).
Older, quality amps, were built to work into the lower impedances. They exp ected it. They KNEW woofers were inductive BECAUSE THEY WERE. Back then.
OK they still are, but it is still less turns of thinner wire to get the sa me "impedance".
Anyway, enough of my treatise here, just agree, disagree, respond, call me a nut or an old fogie, but back to the Watkins. I saw one, or one of its cl ones a long time ago and got the idea. It is an enhanced woofer, the voice coils are probably of different impedances. (enlighten me if...)
Then I hear of them in the manual for the Phase Linear 400, that the extrem ely high value cap in the crossover causes an anomoly when the Phase Linear shuts down. I forgot what the fix is, but what I remember is that there wa s a fix.
I have many questions about this. For example, is it special wound to avoid mutual inductance and/or coupling between the two voice coils ? Or is that just dealt with some other way ? If that huge capacitor is acroos either v oice coil, doesn't it at least damp the cone in the expected way ?
All in all, it doesn't seem like a very efficient system, but then if effic iency was the prime directive of course, we would have, well, what we have today. Speakers that can claim to handle 100 watts at 8 ohms, but are not i nductive. Amps that can claim 100 watts, into a resistor, but into a REAL s peaker would choke. Either the protection would kick in or it would fry run ning some oldies but goodies.
And we used to stack them. Like a pair of Boston A-150s wired in parellel w ith a pair of EPI 100s or something, regardless of whether the speaker swit ch wired them in series or not. (wiring A + B speakers in series should be an indictable offense, IT IS CHEATING and it FUBARS the respnse of both pai rs)
So actually, to the OP I must offer this disclaimer - Whatever you do, when you go to listen to these speakers and enjoy them, get an amp that is abou t 30 years old.