BIF,
Thanks for the info. Let me clairfy this part which many people make the same mistake.
I've heard this from ESL owners where the impedance rises in the bass to very high values. They believe that OTL amplifiers are better for their speakers because they can supply the extra voltage to drive the high impedance in the bass. They indeed get more bass if the damping factor is low, but not the bass the speaker was designed to give. They get more and perhaps like more but it is one note bass.
Speaker makers are doing a better and better job making speakers have flat response, which is a good thing. To to this they generally let the impedance do what it will. They could add a lot of parts to the crossover to try to flatten the impedance curve but they assume you are using an amplifier with reasonable damping of 10 and above. Ten is not a hard limit but 5 is better than 1.
This is where we get in trouble with the power paradigm which had led people to believe that the speaker wants constant power. It does not. I cannot think of or find a modern speaker that wants constant power, the varying impedance and flat response insure that the designer uses a constant voltage amplifier, ie one with high damping.
The reason that John Atkinson puts the response with the simulated speaker first is that he and I feel it is the first thing you are going to hear when you audition that amplifier.
What the power paradigm is saying is that flat response is not as important as ills of feedback. Sorry, but I am not in that camp. Proper feedback has no ills. The Futterman amplifiers have over 60 dB of feedback and a good reputation. Thats a lot of feedback, more than most transistor amplifiers. I plan to start a thread on the Futterman design when I get done with this topic.
Since everyone hears what they hear and like what they like I would rather not promote one paradigm over the other, I just want to point out what is going on based on my experience and my rules of amplifier and speaker design.
I would rather see all speakers have flat impedance curves but this is not how the world is currently set up. Even the DeVore (which has been recommended) has wide impedance variations.
While I agree with JA and Ralph that it is easy to drive (stays above 8 ohms) its peaks go off the chart above 20 ohms. A damping factor of 1 or 2 or 3 will modify the nicely flat frequency response several dB.
http://https//www.stereophile.com/content/devore-fidelity-orangutan-o96-loudspeaker-measurements
Thanks for your question, I hope this clears it up for you and others. Feel free to ask for any further clairication.
Thanks for the info. Let me clairfy this part which many people make the same mistake.
Max power may be compromised at higher impedance, but if I am not pushing the amp, that shouldn't be a problem.
I've heard this from ESL owners where the impedance rises in the bass to very high values. They believe that OTL amplifiers are better for their speakers because they can supply the extra voltage to drive the high impedance in the bass. They indeed get more bass if the damping factor is low, but not the bass the speaker was designed to give. They get more and perhaps like more but it is one note bass.
Speaker makers are doing a better and better job making speakers have flat response, which is a good thing. To to this they generally let the impedance do what it will. They could add a lot of parts to the crossover to try to flatten the impedance curve but they assume you are using an amplifier with reasonable damping of 10 and above. Ten is not a hard limit but 5 is better than 1.
This is where we get in trouble with the power paradigm which had led people to believe that the speaker wants constant power. It does not. I cannot think of or find a modern speaker that wants constant power, the varying impedance and flat response insure that the designer uses a constant voltage amplifier, ie one with high damping.
The reason that John Atkinson puts the response with the simulated speaker first is that he and I feel it is the first thing you are going to hear when you audition that amplifier.
What the power paradigm is saying is that flat response is not as important as ills of feedback. Sorry, but I am not in that camp. Proper feedback has no ills. The Futterman amplifiers have over 60 dB of feedback and a good reputation. Thats a lot of feedback, more than most transistor amplifiers. I plan to start a thread on the Futterman design when I get done with this topic.
Since everyone hears what they hear and like what they like I would rather not promote one paradigm over the other, I just want to point out what is going on based on my experience and my rules of amplifier and speaker design.
I would rather see all speakers have flat impedance curves but this is not how the world is currently set up. Even the DeVore (which has been recommended) has wide impedance variations.
While I agree with JA and Ralph that it is easy to drive (stays above 8 ohms) its peaks go off the chart above 20 ohms. A damping factor of 1 or 2 or 3 will modify the nicely flat frequency response several dB.
http://https//www.stereophile.com/content/devore-fidelity-orangutan-o96-loudspeaker-measurements
Thanks for your question, I hope this clears it up for you and others. Feel free to ask for any further clairication.
