Official Rythmik Audio Subwoofer thread - Page 613 - AVS | Home Theater Discussions And Reviews
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post #18361 of 18365 Unread Today, 04:58 AM
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Originally Posted by 12B4A View Post
http://education.lenardaudio.com/en/12_amps_8.html

The above link mainly talks about voltage vs. current drive amplifiers but the discussion about high Q vs. low Q speakers in relation to the perception of "aliveness" makes for a good explanation of what's really going on. While not addressed in the article, it also explains why subwoofers have become a necessary addition to most modern low Q speaker systems.
It would be interesting to hear Brian's thoughts on that article. What I got out of the article is that high feedback amps allow the use of efficient drivers with a high degree of driver control. A servo design takes driver control even further than high feedback amps. Good room correction can take this even further, canceling out early reflections and room resonances. That said, room correction can only correct linear distortion, while servos and feedback can correct for nonlinear distortion. They are complementary.

I'm not an expert on this stuff, just an interested consumer, but my understanding is that current drive amps react in a different way to speaker impedance, altering the frequency response. Since virtually all modern passive crossovers are designed to be used with standard voltage drive amps, voltage drive is the way to go if you want the speaker to sound like the designer intended. Current drive may sound different, and you might happen to prefer that difference with your speaker, but that doesn't make it better for everyone.
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post #18362 of 18365 Unread Today, 05:02 AM
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Originally Posted by BDP24 View Post
I'd love to hear some JTR's. I haven't seen or heard a high-sensitivity loudspeaker at a retail outlet, or at a Hi-Fi Show, in many years.
Unfortunately, the forces that make for great distribution and great products have very little to do with each other.

It certainly applies to Rythmik.

Bose has great distribution.
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post #18363 of 18365 Unread Today, 06:54 AM
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Originally Posted by rcohen View Post
It would be interesting to hear Brian's thoughts on that article. What I got out of the article is that high feedback amps allow the use of efficient drivers with a high degree of driver control. A servo design takes driver control even further than high feedback amps. Good room correction can take this even further, canceling out early reflections and room resonances. That said, room correction can only correct linear distortion, while servos and feedback can correct for nonlinear distortion. They are complementary.

I'm not an expert on this stuff, just an interested consumer, but my understanding is that current drive amps react in a different way to speaker impedance, altering the frequency response. Since virtually all modern passive crossovers are designed to be used with standard voltage drive amps, voltage drive is the way to go if you want the speaker to sound like the designer intended. Current drive may sound different, and you might happen to prefer that difference with your speaker, but that doesn't make it better for everyone.

That's why I take a good look at John Atkinson's measurements of power amps being reviewed. He often comments on how the tube amp he's testing will sound different with different speakers because of it's high source impedance reacting to the varying impedance load of many loudspeakers. A few tube amp designers do their darndest to get that figure low, Roger Modjeski of Music Reference/Ram Tubes being one.

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post #18364 of 18365 Unread Today, 06:57 AM
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Originally Posted by rcohen View Post
Unfortunately, the forces that make for great distribution and great products have very little to do with each other.

It certainly applies to Rythmik.

Bose has great distribution.
The Newport Hi-Fi Show later this month is a great opportunity for Direct Sales companies to get their products before the public. Peter Hsu regularly displays his subs and loudspeakers at consumer Hi-Fi shows.
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post #18365 of 18365 Unread Today, 08:19 AM
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What the heck is "linear distortion"?

In any event, servo control puts the driver itself in the feedback loop so various distortion sources can be compensated. A high-power amplifier, or at least one with low output impedance, can reduce some distortion by better controlling the voltage (and current) at the driver, but does not help compensate distortion the driver itself generates.

The room is a separate thing and has no practical bearing on the subwoofer's distortion, and distortion in the sub has no real bearing on the room. The only possible correlation I can see is when a room null or peak happens to be placed to cancel or increase the distortion component from the speaker but that is only at certain discrete frequencies. A good speaker/sub won't help a bad room, and a bad room can make a good speaker/sub sound bad.

Current or voltage drive, what you hear depends upon how the circuit is designed and how feedback is applied, things well beyond the scope of this thread. The vast majority of amplifiers are voltage-mode; I am not aware of any current-mode designs available today but I certainly do not know them all.

I have an article over on WBF that shows how amplifier and speaker impedance interact to change frequency response.

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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f12g subwoofer , Rythmik , Rythmik Audio , Rythmik Audio F12 Direct Servo Subwoofer , Rythmik Audio F15 Subwoofer , servo sub



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