Welcome! Need support, you got it. Or share your ideas and experiences.
Return to Planar Speaker Asylum
207.189.194.245
In Reply to: RE: "extending the lower bass of the panels" ... posted by josh358 on March 18, 2017 at 19:52:00
I have seen in-room measurements of the MG 20, 20.1 and 20.7. There use to be a drop in the lowest octave. They cannot simply move that much air. My Tympani IIIA basses are similar, the lowest resonant frequency is 33-34 Hz and from there it drops by about 18 dB/octave. The 3.6 I am using today are also driven by an active crossover and four channels of power amplification. They are not doing much below 40 Hz. Maybe I have to continue my modification of the Tympani IVa...
PS. Kettle drums = timpany? Timpany is playing at higher frequences, from about 55 Hz and upwards. What you hear in that track is the orchestral bass drum at about 35 Hz or so. Here an analysis of that track.
http://www.forumbilder.com/image/E85
Follow Ups:
The room reinforcement from early front wall reflections would reinforce the bass by 3 dB at half a wavelength path length difference, so if the speakers are 5' from the front wall you'd get cancellation at 100 Hz (10' wavelength and path length) and reinforcement at about 50 Hz (20' wavelength and 10' path length) rather than the bottom octave. At 20 Hz you're talking a 50' wavelength so you'll get a fair degree of cancellation from a 108 degree net phase shift. So it seems to me that a very effective bass trap could potentially increase bottom octave response, though of course it will ultimately be limited by the woofer's resonance.
I didn't see much bottom octave bass when I measured my IVA's but there are two important caveats -- I've moved them and there's delam on the lowest frequency resonant sections. So the measurements probably aren't meaningful and since I'm in the middle of some long-overdue Ebay selling it's going to be a few days before I have a chance to take some new measurements (as a matter of curiosity, I want to compare the response before and after the delamination is repaired).
I think it is a complex mix of reinforcement and cancellation from reflections. Not only from the wall behind and beside the speakers but also from the area around the listening posistion.
Definitely. A room mode calculator will predict what happens pretty well for a rectangular room if you remember that with dipoles, a node is an antinode and vice-versa, and that dipoles excite fewer modes than omnis because of the dipole null, which I think is one of the main pluses for planar bass.
Josh, I'll gladly display my ignorance in exchange for you explaining your statement "with dipoles, a node is an antinode
and visa versa". If you share your knowledge with me (and others), assume I know nothing, which ain't far from the truth! I understand that bass frequencies collect in a room at locations (nodes/modes. Are they one and the same? Also called standing waves, right? More things I don't know!) and frequencies determined by the rooms dimensions. What is an antimode, and why the reversal with dipoles? Thanks---Eric.
Edits: 03/20/17
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: