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In the Forum: Playback Listening
In the Thread: Remedies the Beauty
Post Subject: Bass analysis continuedPosted by N-set on: 6/19/2024
I'm going around with the Dannoy bass augmentation like, as we say in Polish, a chicken with an egg. I posted my problems on DIY audio and managed to get some interesting comments from a gentleman named Art who was kind enough to educate me a bit. Here is what came out of the discussion:
0) To set the terminology, what I want is augmentation rather than extension per se as I wanted to run the Dannoys unfiltered (no high-pass filter) not to affect its wonderful bass.
1) The wonderful bass can, in part, be a result of the bump in the 50-70Hz region, sth that Romy also mentioned. The guy called it "loundness contour" and suggested that in order to properly augment it, I need to keep the bump down to some 30Hz (based on my mean field measurements):
2) Getting +25dB @ 30Hz seems monstrous but the Fletcher-Munson curves come to help: the perceived loudness increase at LF costs much less dB than at higher freq. Perhaps even as low as +3-4dB can help
3) The integration of a PR design with a woofer should in principle be not more complicated than a ported design and the complicated phase response at LF should not be problematic (in principle)
4) My idea of a PR woofer (1 Scanspeak active + 1 PR) looks weak as the PR speaker will reach max excursion very quickly. So looks like a sealed box or a ported one is the way
5) Sth I did not understand: Art kept insisting that I did not present any arguments that I need augmentation. My arguments of a sonic nature (the sound of big orchestras misses the size and impact on LF + missing LF spatial information) and a physical one (a single 10" cone simply cannot produce any appreciable SPL below 50-40Hz) and the measurements were not convincing. No idea what he meant, he then lost interest in the thread.
The discussion is here: https://www.diyaudio.com/community/threads/adding-low-bass-channel-to-a-passive-radiator-design.413147/#post-7700542
So at the moment looks like I'm gravitating towards Romy's original bass design from old Macondo: 2xScanspeak 25W/8565-00 in a sealed box of Fb=39Hz (~90l) This is about max size I can try fitting in the room. If I hang them by the ceiling (getting +6dB boost), there would be around 70cm path difference between the Dannoy and the woofer to the listening position, so I guess a delay of 2ms the woofer would be needed.
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