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In Reply to: Re: Apples and oranges posted by djn on January 13, 2005 at 12:49:55:
I will show my ignorance of horn speakers by admitting that I have never heard of ANY of the drivers you mention, but it is enough to know that your midrange driver is rated at 24 ohms impedance. This is OTL heaven! You can use anything you want, but I would try the Atma-sphere S30 and the Berning Siegfried for starters. I think eventually you will want to replace the Crown amplifier driving your woofers with a second OTL, too. OTLs, particularly Atma-sphere ones, deliver superb, deep, and articulate bass into a high-impedance load.
The 515G woofers are also 24 ohm. Now it is my turn to admit my ignorance, I was always told that if an amp rated at 10 wpc, lets say, into an 8 ohm driver, then it was only good for something less than 10 wpc when driving a speaker with 16 or 24 ohms. Is this true or false? If it is true then I would need to rethink the power required when buying an amp. Cheers.
Transistor amps tend to produce power in inverse relationship to speaker impedance. In other words, an ss amp rated at 100W into 8 ohms might make 200W into 4 ohms. This relationship has limits and is dependent upon the power supply design and execution. So for example the same amplifier probably would not develop 800W into a 1 ohm speaker. (It would probably explode first.) Conversely, tube amplifiers tend to develop more power into higher impedance speakers. This is because transistor amps are "current amplifiers" while tube amps are "voltage amplifiers". I hate to repeat that confusing bit of mumbo jumbo, because it does not tell you anything. Think of it this way: Power = current X voltage. SS amps are better at making current and tube amps are better at making voltage. Tube-type OTL amplifiers certainly tend to like high impedance loads better than low impedance loads. This is not only due to the foregoing rationale but also to the fact that OTLs tend to have high-ish output impedances, which makes it doubly difficult for them to drive low impedance speakers. (You want the output impedance of your amplifier to be significantly less than the input impedance of your speaker for best results.)
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