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Hyperbolic bass horns |
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citizensc 
Young Croc 
Joined: 16 October 2015 Location: Perth,Australia Status: Offline Points: 532 |
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 Posted: 09 September 2020 at 7:27am |
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Simple question but I haven't been able to find the answer. How do you calculate rms? Driver diaphragm suspension mechanical resistance (n.s/m). I know hornresp can do it but I want to know the formulae.
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snowflake
Old Croc 
Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3120 |
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Posted: 09 September 2020 at 11:24am |
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Rms=(1/Qms).((Mms/Cms)^1/2)
Edited by snowflake - 09 September 2020 at 11:26am |
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citizensc
Young Croc
Joined: 16 October 2015 Location: Perth,Australia Status: Offline Points: 532 |
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Posted: 12 September 2020 at 10:23am |
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Thanks a bunch! Just a side note: In the leach paper wc is the angular resonant frequency of the driver in box, w0 is the horn angular cutoff frequency.
In the Kolbrek paper it is the other way around, wc is angular cutt off of the horn, w0 is the resonant frequency of the driver in box. Hope no one else wastes an hour trying to figure out why the formulae don't make sense because of this. |
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snowflake
Old Croc
Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3120 |
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Posted: 12 September 2020 at 2:24pm |
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He also uses wl to mean two different things. as in Leach it is used as the -3dB point of the midband range (which beause of his new reactance annulling method is a lower frequency than wc), but also in section 6 he uses wl as a target frequency to achieve maximum output power (which is necessarily above wc).
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snowflake
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Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3120 |
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Posted: 24 November 2020 at 10:44pm |
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not sure if this is any help but you can make the rear chamber very small and put a capacitor in series between the amp and the horn to get approx the same response. does this give you some extra freedom with the reactance annulling or is the capacitance exactly equivalent to the chamber compliance?
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snowflake
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Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3120 |
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Posted: 26 November 2020 at 12:20am |
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playing around with Hornresp it seems possible to get slightly reduced excursion in the passband and slightly improved response by using a capacitor and making the rear chamber smaller. I'm far from sure that the reactance of the capacitor is an exact substitute for the reactance of the chamber, but one advantage could be that when Kolbrek's maths requires a very large chamber for reactance annulling, using a cap could reduce chamber size and significantly reduce the overall cabinet volume. This means you could use a larger Sd driver on a low-T horn.
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Comode
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Joined: 20 January 2022 Status: Offline Points: 1 |
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Posted: 27 January 2022 at 9:51am |
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Hi Citizensc,
i just started to think about horn theory and calculation. It's quiet hard to get into it. so for that i would be really thankfull if you could send me a copy of your spreadsheed. Best regards Klaus
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snowflake
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Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3120 |
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Posted: 17 August 2022 at 12:53pm |
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this is a useful explanation of some of Kolbrek's ideas without so much maths:
My Approach to Bass Horn Design (hornspeakersystems.info) |
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snowflake wrote: