FWIW, the physics of ESLs do not help solid state amps out. That's why you see so many people saying how you need a big powerhouse amp. Here's why:
Most solid state amps will double power as the load is cut in half. What this also means is that the power is cut in half as the load doubles. A lot of ESLs have impedances in the bass region that are 16 ohms, and there are 30 and 50 ohm designs out there. A 600WPC solid state amp will make only 150 watts into 30 ohms...
Another issue is the ESLs are not voltage driven as is often suggested. True- at the panel itself this is probably the case. Unless the speaker is direct-driven with its own built in OTL high voltage amp, it has an input stepup transformer. This takes power to drive. The impedance curve of the speaker is based on the fact that it is a capacitor, and not a box with resonance, so the traditional argument for an amp with a 'constant voltage' characteristic is right out.
You need an amp that makes constant power, not constant voltage. To do that, you need tubes and you will need tubes with some power (the exception seems to be the Quad 57 and 63). 200 watts is usually enough though, and from looking above we see why: a 600 watt transistor amp will not make significantly more power than a 200 watt tube amp in this case.
Often the manufacturer wants to cash in on the transistor market, and so has set the bass frequencies at 8 ohms with the matching transformer. This can have the 20KHz impedance at 0.5ohm -hard for a tube amp. There are some Martin Logans set up like this. In such cases if you use a tube amp, you might also use a set of ZEROs for best results.
The Innersound amp seems to be designed to get around some of the issues I outlined here, but due to its need for negative feedback is not 100% successful. The constant power issue is daunting.
Since the 1950s, OTLs (now for the horn tooting) have been the classic combo with ESLs, probably because of the higher impedances used at the time and also because its one less matching transformer in the chain. We introduced the MA-2 in 1990 and the 2 primary speakers they seem to get used on are Sound Labs and Avalon Eidelons.
For the most part, ESLs do not strike me as inefficient. You can drive almost all of them easily with 100 watts if you can actually get the amplifier to make 100 watts on the load. *That* is the tricky part!
BTW, the idea of high voltage rails somehow helping out with the amp's ability to drive the speaker is not really true. Once you work out the math you see why- just keep in mind the speaker is power driven, not voltage driven and the reason will be apparent.
Most solid state amps will double power as the load is cut in half. What this also means is that the power is cut in half as the load doubles. A lot of ESLs have impedances in the bass region that are 16 ohms, and there are 30 and 50 ohm designs out there. A 600WPC solid state amp will make only 150 watts into 30 ohms...
Another issue is the ESLs are not voltage driven as is often suggested. True- at the panel itself this is probably the case. Unless the speaker is direct-driven with its own built in OTL high voltage amp, it has an input stepup transformer. This takes power to drive. The impedance curve of the speaker is based on the fact that it is a capacitor, and not a box with resonance, so the traditional argument for an amp with a 'constant voltage' characteristic is right out.
You need an amp that makes constant power, not constant voltage. To do that, you need tubes and you will need tubes with some power (the exception seems to be the Quad 57 and 63). 200 watts is usually enough though, and from looking above we see why: a 600 watt transistor amp will not make significantly more power than a 200 watt tube amp in this case.
Often the manufacturer wants to cash in on the transistor market, and so has set the bass frequencies at 8 ohms with the matching transformer. This can have the 20KHz impedance at 0.5ohm -hard for a tube amp. There are some Martin Logans set up like this. In such cases if you use a tube amp, you might also use a set of ZEROs for best results.
The Innersound amp seems to be designed to get around some of the issues I outlined here, but due to its need for negative feedback is not 100% successful. The constant power issue is daunting.
Since the 1950s, OTLs (now for the horn tooting) have been the classic combo with ESLs, probably because of the higher impedances used at the time and also because its one less matching transformer in the chain. We introduced the MA-2 in 1990 and the 2 primary speakers they seem to get used on are Sound Labs and Avalon Eidelons.
For the most part, ESLs do not strike me as inefficient. You can drive almost all of them easily with 100 watts if you can actually get the amplifier to make 100 watts on the load. *That* is the tricky part!
BTW, the idea of high voltage rails somehow helping out with the amp's ability to drive the speaker is not really true. Once you work out the math you see why- just keep in mind the speaker is power driven, not voltage driven and the reason will be apparent.