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In Reply to: Wood Effect question. posted by richardl on May 7, 2007 at 12:23:53:
The first issue is to be sure all of the speaker's drivers are in the same polarity. Not all speakers are designed this way.... Often, the driver placement and characteristics make inversion of one driver relative to the other more "seamless" in response at the crossover frequency. (The best check for this is the acoustic impulse or step response. Most speakers do poorly here, but the relative polarity amongst the drivers can be determined quite easily.)The second item is that more-often than not, if the music sounds "louder" at the same volume level, I usually find the sound worse. I think due to increased distortion components. Except for the frequency extremes- Non-inverted playback seems to go deeper in the bass and have more acoustic "air" and "sparkle" at HF.
Follow Ups:
I created the crossover and yes it is a 4th order LR and therefore the tweeter is 180 degrees out of phase with the mids. That is why I was shocked to hear a difference. I carefully phased everything when I switched. The effect wasn't there on everything but, on the few very good classical recordings that had sounded a little funny, they sounded better. I am not sure louder is the right word, tighter and more natural in that it was sudden response to drums and horns rather than leaden response.
"I created the crossover and yes it is a 4th order LR and therefore the tweeter is 180 degrees out of phase with the mids. That is why I was shocked to hear a difference."You'll still hear a difference.... It's just one of the setups won't likely sound better outright. Now I think it would be a different story if all the drivers were in relative phase. Even if they're not necessarily time-aligned.
c
Gents:Our man clearly stated that he changed the polarity of ALL connections after the crossover. This means that there was no relative polarity change between drivers.
The only time you change the amplitude response is when you flip one (or some) drivers but keep one (or some) drivers in the original wiring. An example would be a 3rd order Butterworth 3-way, which often calls for reversal of the midrange to sum flat. If you switch the leads on the midrange ONLY, the amplitude response will change. If you switch the leads on ALL drivers, the amplitude response should not change.
Driver polarity is over-rated anyhow. 4th order Linkwitz Riley crossovers have their drivers wired with the same "polarity", but this does NOT mean the system is phase-coherent.
Most people are happy when a + voltage to the + terminal (pre-crossover) would result in forward cone motion of ALL drivers. This is great for recordings that "match up" to this convention. I think Clark's main point is that if recording polarity is typically arbitrary, then such "conventions" are not worth a lick. If that is what he means, then I concur fully.
Please email me: Audioexcels@yahoo.com
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