Originally Posted by LTD02
"listen to two identical tapped horns, one loaded with a driver with a Qes of 0.3, and one with a Qes of 0.7."
ack...this is a tough one. do you think that such a test is possible? man, trying to control every other variable in order to narrow it all the way down to just qes and nothing else seems like it would be a beast of an engineering chore in a tapped horn. i suspect what you are preferring are many artifacts that attend a particular design, not simply qes, but as always, i could be wrong.
That was a quick post from my phone last nite - guess I could have worded it better. I do think a test such as this is possible, I've done several that are quite similar already, and will do more. What I have done (so far) is use several different (but still appropriate) drivers in the T-6 design, as well as a precursor to it that was similar to the Insubnia that Erich flat-packed.
While the frequency response modeled flat, and measured similarly, the drivers with higher Qes just did not sound as detailed or accurate. This was not just my ears either - several others noticed immediately. The sub was muddy and simply not able to articulate music as well.
So - I tried a little science project. After making sure that all else was as equal as I could make it (same horn, same amp, same measurement gear, same day, same setting, just different drivers), I measured things again to try and figure this out.
I'm still not 100% sure that I have, but I do have a theory. In a simple frequency response plot, I can definitely tell you that this difference is not evident - the higher Q driver actually has a flatter response, and "should" sound better as a result, but that was simply not the case.
Look at a waterfall plot for both measurements though - the difference is as clear as day. Once excited, the horn's resonances take longer to decay with a high Qes driver, cause it "has weak brakes", which leads to a muddier sound with real-world content. I also found that my little amp did not like driving the higher Qes driver, it actually overheated and shut down. The DC resistance and impedance of the drivers was similar, and appropriate for the amp. When I switched up to a much stronger amp, the sound improved, but so did the sound of the lower Qes driver.
Anyhow - this is a work in progress.
The more I learn, the more I find out that I need to learn more......