Fostex 206En missing values for Hornresp

[CraigWilliams]

Hello World,

This is my first post and first time building a diy speaker.

I have a set of Fostex 206En drivers and i'm looking to design my own BLH enclosure. Why deviate from the enclosure design that Fostex recommends? My understanding of audio engineering has taught me that parallel sides on a Horn potentially cause unwanted standing waves, wrong? Also, I just want to tinker a bit and create something unique.


So, i'm getting to know Hornresp as many people seem to give it top reviews.

I've realised the Fostex data sheet does not include some values that Hornresp asks for. The unknowns are as follows:

Mms = Mmd + ‘Air Load’ Is Air load negligible?

Rms = (2Pi x Fs x Mms)/Qms

Where Fs = 45Hz, Mms = 12.2g, Qms = 4.57

Therefore,

Rms = 754.807 Hz.g Correct?


Any help on this would be greatly appreciated!

Craig

 

[Zero D]

Hi, as you enter the specs you have, HR can calculate the missing ones 😉 For eg,

 

[David McBean]

Hi Craig,

Mms = Mmd + ‘Air Load’ Is Air load negligible?

No. For your Fostex driver, 'air load' = 3.21 grams.

Rms = (2Pi x Fs x Mms)/Qms

Where Fs = 45Hz, Mms = 12.2g, Qms = 4.57

Therefore,

Rms = 754.807 Hz.g Correct?

Not quite 🙂.

Rms = 1 / (2 * Pi * fs * Cms * Qms)

Rms = 1 / (2 * Pi * 45 * 1.17 * 10 ^ -3 * 4.57)

Rms = 0.66 newton.sec/m

To determine the electro-mechanical equivalents for the given Fostex Thiele-Small driver parameters, use either the technique suggested by Zero D to calculate just the individual parameter values you require, or alternatively, double-click on the Sd input box in Edit mode to enter all the Thiele-Small values at once (see attachment).

Kind regards,

David

 

[CraigWilliams]

Thank you both so much! Two great ways to solve my problem. Time to produce some graphs and check if my theory is correct.....hmmm.