November 20th, 2017, 1:40 pm
SoundMods wrote:Cogito wrote:Tom,
I am confused because, the spread sheet you gave me hows the resonance frequency going down as the volume of the sealed box increases. I am equating the resonance frequency with bass response. Chris's modeling shows there is not particular correlation between volume an f3.
Which is more relevant for determining bass response, resonance frequency fs or f3?
BTW, I found references online that xmax 7mm in each direction or 14mm total.
I felt the need to jump in here. The simple answer to your question is both.
The lowest woofer resonance you can obtain is the free-air resonance. That's with the woofer sitting on a counter out in the open. Box loading raises the measurable system resonance. The bigger the box the lower the speaker resonance. Since any of the practical box sizes do not represent a true infinite baffle you will be limited by the box size. Linear excursion peak-to-peak is the other limiting factor. Woofers as a generic group are designed to "pump" air with long travel of the cone. Or -- you can use bigger woofers. Electrovoice made a 30-inch diameter woofer that could do 20-hz in the box. WOW!
F sub s would be the speaker resonance in the box and F sub 3 is the response that is 3-db lower than the over-all average from that frequency and higher. Or where the roll-off is considered to start and considered the low frequency response limit of the speaker.
I hope this helps.
November 20th, 2017, 3:33 pm
tomp wrote:SoundMods wrote:Cogito wrote:Tom,
I am confused because, the spread sheet you gave me hows the resonance frequency going down as the volume of the sealed box increases. I am equating the resonance frequency with bass response. Chris's modeling shows there is not particular correlation between volume an f3.
Which is more relevant for determining bass response, resonance frequency fs or f3?
BTW, I found references online that xmax 7mm in each direction or 14mm total.
I felt the need to jump in here. The simple answer to your question is both.
The lowest woofer resonance you can obtain is the free-air resonance. That's with the woofer sitting on a counter out in the open. Box loading raises the measurable system resonance. The bigger the box the lower the speaker resonance. Since any of the practical box sizes do not represent a true infinite baffle you will be limited by the box size. Linear excursion peak-to-peak is the other limiting factor. Woofers as a generic group are designed to "pump" air with long travel of the cone. Or -- you can use bigger woofers. Electrovoice made a 30-inch diameter woofer that could do 20-hz in the box. WOW!
F sub s would be the speaker resonance in the box and F sub 3 is the response that is 3-db lower than the over-all average from that frequency and higher. Or where the roll-off is considered to start and considered the low frequency response limit of the speaker.
I hope this helps.
RIght on except for one point. Fs is free air resonance and Fb is resonance in whatever enclosure into which you place the driver.
November 20th, 2017, 5:29 pm
November 20th, 2017, 5:54 pm
November 20th, 2017, 6:05 pm
November 20th, 2017, 6:14 pm
Cogito wrote:Thanks Tom and Walt.
The box calculations based on T/s parameters seem to be an approximation under some "assumed" conditions. By that I mean, there doesn't seem to be any allowance for
1. Input power
Cogito wrote:2. Strength of the magnet
November 20th, 2017, 6:19 pm
November 20th, 2017, 6:40 pm
Roscoe Primrose wrote:Cogito wrote:Thanks Tom and Walt.
The box calculations based on T/s parameters seem to be an approximation under some "assumed" conditions. By that I mean, there doesn't seem to be any allowance for
1. Input power
November 20th, 2017, 7:34 pm
November 20th, 2017, 7:42 pm
chris1973 wrote:BTW, I found references online that xmax 7mm in each direction or 14mm total.