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SET Asylum Single Ended Triodes (SETs), the ultimate tube lovers dream. |
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SET Asylum Single Ended Triodes (SETs), the ultimate tube lovers dream. |
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In Reply to: RE: That's funny... posted by RGA on August 13, 2011 at 20:46:39:
A solid state voltage source amp into a low speaker impedance like 2 ohms plays louder than 4 ohms or 8 ohms. This we know. It doesn't make the lower impedance loads more efficient in actuality, as any tube amp would require a need to change impedance taps for each condition. The SS amp if very strong in current can keep on delivering more power out into lower speaker impedances, but the watts are also increasing, not making this actually more efficient. But some manufacturers will show a dubious figure like 91dB/2.82V/1m, where the voltage of 2.82V will deliver one watt into only 8 ohms. But the intended amp with it works in lesser impedance, and thus this figure is misleading. Then at 4 ohms the power is actually doubled by the voltage source SS amp to 2 watts.
True speaker efficiency is measured in percentage. It's the amount of acoustic power developed for power inputted. A driver could be 2% or 20% efficient. An open framed driver is much less efficient than the same in a loaded compression chamber. There's physics there I don't care to get into.
Then after the efficiency is increased, the sensitivity can be increased which might be 110dB/1W at 1m away. This will be done by the method of impedance matching to the air, and waveguiding the output of the driver to concentrating the energy with directionality to a narrower beam.
Impedance contouring and control is another effort to ease the load for the amp, and by electrical theory all amps like an easier load to drive to make voltage out remain what it should be.
There is a fallacious theory about SET amps that high output impedance makes them unable to follow even minor impedance changes with frequency. Actually, the voltage sourced amp is harder to make a flatter acoustic response to small variations. SET amps are partially voltage sourced and partially power sourced outputs into speakers.
With a 'flat' response speaker, a SET amp will *RAISE* power output when a small impedance rise occurs: small higher impedance usually correlates with small lower output from the speaker with the crossover. Only the open zero NFB amp can help. On extreme impedance change, it's not as good.
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Follow Ups
- Efficiency vs. sensitivity and then there's impedance - kurt s 23:13:18 08/13/11 (0)
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