EBP>100 but X-point is 350Hz.

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Oneminde

Oneminde

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Joined 2014
#1
The driver has an EBP of 106 and Qts 0.29 - this dictates that I should use a ported enclosure. But the crossover will be 350 Hz, well above the bass region (20-200Hz) and so I have a question.


Spite not using the driver (5") in the bass region, does it still demand a port ?
 
#8
Galu said:
A back of the envelope calculation would suggest a closed box of volume around 4 litres (0.14 cu ft) used, of course, with a suitable filter.
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Interesting, how do you arrive to that volume ? What I mean is which parameters do you adjust when you consider the x-point and not the Fs/Fb of the system ?


I will actually par this midrange with the Wavecor WF182BD03 (7") which will be used between 100-350 Hz, and the Peerless SDF-250F75PR01-06 (10") for the 20-100Hz. And I don't intend to use a port for the Wavecor either, only on the Peerless.



Still learning stuff and if you have relationship I can consider for the box calculations when x-point matter, that would be swell.
 
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#9
My calculations assumed a system Q of 0.7, giving Fb/Fo = 2.4 and Vas/Vb = 5 approx.

This merely predicts a suitable closed box volume for this driver in normal use.

I'm afraid I do not understand what you mean by "which parameters do you adjust when you consider the x-point".
 
#11
Galu said:
My calculations assumed a system Q of 0.7, giving Fb/Fo = 2.4 and Vas/Vb = 5 approx.

This merely predicts a suitable closed box volume for this driver in normal use.

I'm afraid I do not understand what you mean by "which parameters do you adjust when you consider the x-point".
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I will do manual calculations, until the - which is later today - I used: Speaker Box Enclosure Designer / Calculator


This gives a Vb of 21 liters. I know in this scenario, this will be off due to the much higher x-point, so Fs is of no concern. So, you changed some parameters or used a different set of calculations to get Vb = 5 ... that is what I am asking for 🙂 - what or how
 
#12
Just discovered a tiny issue in my calculations. Anyho... Vb is anything between 4-10 liters and is adjusted by the Qtc as all of you know. Qtc seem to be the only thing one can adjust and x-point cannot be considered for the box calculations.
 
#15
Oneminde said:
The driver has an EBP of 106 and Qts 0.29 - this dictates that I should use a ported enclosure IF I intend to use the driver down to it's low-corner below the EBP range (in the stop band under the EBP octave).
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Fixed it for ya. 😉 Qts is a T/S parameter that is used to model a driver in the low-corner. If you consider the EBP = Fs/Qes, you arrive at a number who's units is Hz. Go one octave higher and you have the EBP Mid-band. This [range] is where the speakers rated efficiency/sensitivity manifest itself strongly. Below this mid-band is the stop-band, or low-corner, where the sensitivity is largely determined by the low end alignment chosen by the end-user. <-- that is where T/S analysis shines. Therefore, if you cross over within the mid-band or higher, the requirements used to maximize/manipulate low-frequency output no longer apply because it is not a design requirement.
 
#20
midrange said:
I am interested as to why you are using those drive units and those xover frequencies.
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Well... there are a few, but the dominant ones are
1. They are among the best in their class, aka 5" and 7".
2. I want to stay within the 3 octave rule when possible.
3. The 3 octave rule dictate a 4-way or possible 5-way.
4. The drivers where chosen due to designing a loudspeaker which is inspired by Aduio Physic Codex/Structure.
5. Because I have limited width available for the loudspeakers and need a side firing LF woofer.
6. So yes there is also a 10" and the top end are actually two SEAS alu tweeters which complete one another aka normal and super. Effectively making this a 5-way

🙂
 
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