Apologies to the list for going wildly OT and staying there for a bit.
On 19 April 2011 17:00, Ken Norton <ken@xxxxxxxxxxx> wrote:
> My all-time favorite sound-system was a bi-amped pair of Tannoys
> powered with two sets of Yamaha sound-reinforcement amplifiers.
I have a pair of bi-amped Tannoys... but not the sort you allude to.
Mine are 638s (8" DC & 8" woofer in a trapezoidal dual-chamber reflex
cabinet) driven by a couple of home made MOSFET amps and a home made
active crossover. I like them ;) Would love to have a pair of 15"
Golds or HPDs in GRF corner cabinets though (also bi-amped)
> Yup, I loved those
> Tannoys and have kept an eye out for second-hand studio units for
> years, but the engineers in those studios seem to lay claim to them
> when they get decommissioned.
I hear that Paul McCartney nabbed a pair from Abbey Road, which gives
you some idea of how high & mighty you have to be ;) Best bet is
probably to try and score an old pair of Lancasters, chuck the cabs on
a bonfire and build something decent yourself to put them in. Maybe
I'll do that myself one day.
> But back to the amplifiers...
> An amplifier has two purposes: To move the cone and to stop the cone
> from moving.
> Most people don't realize that most speaker transducers are actually
> electrical motors. They're linear motors, but they are still motors.
> The amplifier is passing electricity to the motor to move it. But what
> happens when the elecricity goes away and the speaker is moving? It
> actually becomes a generator.
>
> So, a super-duper amplifier doesn't really need much power, but it
> does need to withstand the generator effect of the speaker.
> Traditionally, the higher-quality tube amplifiers have this capability
> and it's actually more native to the design of a tube amplifier than a
> solid-state amplifier which accomplishes the same task through
> different means.
Hmm, I know I'm still a beginner at this game, and have never played
with valves (tubes) (I've only recently got around to reading books on
the subject so I can stop following other folks' recipes and
understand power amps properly), but I'm having trouble following that
last bit. Surely a solid state amp with negative feedback can sink
the current generated by the voice coil very effectively, giving it a
near-zero output impedance and heavily damping the cone movement,
whereas a valve (tube) output stage has to have an output transformer
that lies outside any feedback loop and thus it's secondary winding DC
resistance contributes to the output impedance and reduces its ability
to damp the speaker cone?
--
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prove you wrong. Remember: when the emperor looks naked, the emperor *is*
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