Hello Everyone. I hope everyone is doing well? I had a engineer person I know tell me that the F3 has to match the FB in the design program. I am using the Tang Band 3W-2141 and its cut off is 75hz. I have it at - 2.48 DB at 75 hz. Does this sound right? A lot of speaker company's do minis or plus 3 DB. I thought you would want the curve as flat and even as possible? So here's a example. The Dynaudio Confidence 20 is 155hz at 6 ohms and goes down to 42hz and up to 22khz at + 3 DB. So where is that plus or minis 3 DB in the frequency response?
Am guessing the curved line is not as flat as mine but, maybe am to anal about this box building? Can you please help me out here. Thanks Jeff
Am guessing the curved line is not as flat as mine but, maybe am to anal about this box building? Can you please help me out here. Thanks Jeff
by Thiele's work, that applies only to the Butterworth 4th order alignment where Qts = 0.383
look at Qts affects tuning/etc. from this snippet of Thiele's alignments (rewritten table by D.B Keele Jr.)
remember that source impedance will raise effective Qts
look at Qts affects tuning/etc. from this snippet of Thiele's alignments (rewritten table by D.B Keele Jr.)
remember that source impedance will raise effective Qts
I'm afraid the 'engineer person' you spoke with is mistaken if he says F3 'has' to match Fb. As you can see from the extract Freddi has posted, that is not the case.
A maximally flat LF alignment might look pretty on a graph, but there is no guarantee that will offer optimal in-room performance; in many cases taking purely the frequency / amplitude response it is in fact unlikely to do so and will cause excess output around that frequency once room-gain is factored in. Therefore, generally speaking if you want a flat alignment they need to be a reasonable distance from room boundaries. Depending on box type & details, they may [may] also have higher GD than other types.
Conversely, the reverse can be useful, the most famous being the LS3/5a nearfield monitor, which used a sealed box Q of about 1.2 to help give the impression of missing LF output, partly derived from the BBC's work on acoustical scaling. And so on. Box loading is not a 'one-size-fits-all' approach; for optimum results you consider the system goals and design accordingly.
Thanks everyone..Now that makes sense to me..I knew something wasn't adding up. I will print the table asap. Yes one sizes fits all is not a real world concept. I know there is trial in error when build a box. You have to fine tune it to what you want it to sould like. Jeff
I was asking once ,what Qt closed box you get if you close the duct of Qb3. Thanks to the table above now I know that Qb3 or B4 you get Qt of 0.6. In other words, calculate the box for your speaker to get Qt of 0.6, then, adjust the length of a given duct to get the best sound or measurement.
Thank you freddi, thank very much.
Hayk
Thank you freddi, thank very much.
Hayk
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here's that full table which comes from the following paper
http://www.xlrtechs.com/dbkeele.com/PDF/Keele (1973-05 AES Published)Sensitivity of Alignments.pdf
re: Fifth order alignments. that's an active 1st order highpass/rumble filter
http://www.xlrtechs.com/dbkeele.com/PDF/Keele (1973-05 AES Published)Sensitivity of Alignments.pdf
re: Fifth order alignments. that's an active 1st order highpass/rumble filter
Another quick rule of thumb.....
Qts above .4, the f3 and tuning (not necessarily the same) go down but box size goes up.
Qts below .4, the box size goes down but tuning and f3 go up above speaker's fs.
Qts above .4, the f3 and tuning (not necessarily the same) go down but box size goes up.
Qts below .4, the box size goes down but tuning and f3 go up above speaker's fs.
Here's that full table from D.B. Keele Jr.'s paper - hopefully easier to see
http://www.xlrtechs.com/dbkeele.com/PDF/Keele (1973-05 AES Published)Sensitivity of Alignments.pdf
http://www.xlrtechs.com/dbkeele.com/PDF/Keele (1973-05 AES Published)Sensitivity of Alignments.pdf
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That discrete alignment does sound very good compared to others in my opinion. Some people don't like vented (bass reflex) boxes because they haven't heard one that is properly implemented. I consider this B4 almost ideal; others will disagree here of course but most of my vented designs are of this alignment (when TSP's work to our advantage here)...FWIW...
ah, NO. NYET. NEIN. NE.
And all the Thiele-Small stuff is fine, but as Dick Small himself would have told you it's a MODEL, and for SMALL signals (no pun intended 😉). For little drivers moving a lot, T-S only vaguely applies as a starting point. Even for bigger drivers, as Chris Strahm's LEAP program pointed out (and later Klippel), things are really more complicated than Thiele-Small. All those alignment tables based on electrical filter theory are just starting ideas.
As for F3, way overrated. Small just used that in his thesis because it was a handy mathematical convenience-he confirmed that to me in a conversation we had in Indiana when he was working at Harman. In real rooms, f6 and f10 and the shape of the curve are more important, and keeping the tuning frequency low so the driver doesn't bottom with low bass is also more important IMNSHO.
Hmm.
I find how low you vent affects sound quality.
40hz is more of a thunk think like a dance club, many professional subs tunes near 40hz.
27 hz goes boom Boom, smoother.
I sealed my 27hz tuned (near 30hz f3) and it wasn’t any “quicker”, just about an octave less bass, and that was sad.
I find how low you vent affects sound quality.
40hz is more of a thunk think like a dance club, many professional subs tunes near 40hz.
27 hz goes boom Boom, smoother.
I sealed my 27hz tuned (near 30hz f3) and it wasn’t any “quicker”, just about an octave less bass, and that was sad.