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citizensc View Drop Down
Young Croc
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Points: 547 		Post Options Post Options   Thanks (0) Thanks(0)   Quote citizensc Quote  Post ReplyReply Direct Link To This Post Posted: 10 June 2020 at 11:07am
Originally posted by David McBean David McBean wrote:

Originally posted by snowflake snowflake wrote:

Does anyone know how Hornresp deals with Qmc?


It assumes no losses.

Qmc = Sqrt(1 + Alpha) * Qms



Thank you for this! after substituting this formulae in for '10' my calculated chamber volumes are exactly the same as hornresp when using 'system design with driver'. They were very close but this explains the small difference. 

How much would you expect this number to change in a real speaker? assuming it is well braced and made of 18mm birch. I know no one can give me an exact figure but will it still be in the same ball park?  
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Points: 3443 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 10 June 2020 at 12:11pm
Originally posted by David McBean David McBean wrote:

Originally posted by snowflake snowflake wrote:

Does anyone know how Hornresp deals with Qmc?


It assumes no losses.

Qmc = Sqrt(1 + Alpha) * Qms



you can make that assumption when designing a system with driver. But when designing from specification we don't know Qmc or Qms.
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Points: 54 		Post Options Post Options   Thanks (0) Thanks(0)   Quote David McBean Quote  Post ReplyReply Direct Link To This Post Posted: 11 June 2020 at 7:34am
Originally posted by citizensc citizensc wrote:


will it still be in the same ball park?  

Yes.

To check for yourself, try using Fr and Tal in Hornresp to introduce losses into the rear chamber to see how the zero-loss results are affected.
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Points: 54 		Post Options Post Options   Thanks (0) Thanks(0)   Quote David McBean Quote  Post ReplyReply Direct Link To This Post Posted: 11 June 2020 at 7:41am
Originally posted by snowflake snowflake wrote:

But when designing from specification we don't know Qmc or Qms.

Hornresp assumes Qmc = 10.

Not sure how often the 'System Design from Specifications' option is actually used, though :-).
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Old Croc
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Points: 3443 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 02 September 2020 at 1:49pm
I've only given it a quick read but this looks very interesting:
https://pdfs.semanticscholar.org/20cf/51865eedcdae8267a9b98c609768d27c0ee2.pdf?_ga=2.108894786.1510181388.1598978440-1722470333.1598978440[URL= ][/URL]
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Old Croc
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Points: 3443 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 02 September 2020 at 1:56pm
he also has a book out. £122 but probably worth it for a 1000 page book

https://hornspeakersystems.info/[URL= ][/URL]
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Points: 231 		Post Options Post Options   Thanks (0) Thanks(0)   Quote kipman725 Quote  Post ReplyReply Direct Link To This Post Posted: 02 September 2020 at 2:28pm
Originally posted by snowflake snowflake wrote:

he also has a book out. £122 but probably worth it for a 1000 page book



Can confirm its a fantastic book, not totally exhaustive though even at 1000+ pages.  Could do with more material on acoustic lenses (and related structures such as paralines) and synergy/MEH horns (2nd edition?).  Worth getting though and some of the history material is surprising; like the WE bass compression driver that when you calculate the output of 5 of them you realize than even in the late 1930s, with enough money you could have decent bass at an outdoor event.
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Points: 3443 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 02 September 2020 at 9:36pm
Originally posted by snowflake snowflake wrote:

I've only given it a quick read but this looks very interesting:
https://pdfs.semanticscholar.org/20cf/51865eedcdae8267a9b98c609768d27c0ee2.pdf?_ga=2.108894786.1510181388.1598978440-1722470333.1598978440[URL= ][/URL]


it seems to me there is some confusion in that paper by wl being used to mean both the lower midband cutoff, and the desired max output cut-off, and wc being used instead of w0 in other places. EDIT: think he consistently swaps wc for w0 from the way Leach defines them.

the bit on reactance annulling is very important though I'm still getting my head around how to incorporate it into a design procedure.

as Leach says, in an infinite horn, for max sensitivity you want Ral=Rat (beta=1), but for max efficiency Ral<Rat (beta<1). The section in Kolbrek on finite horns points out that to minimise ripple in the response you want Ral~Rat (beta~1). You could approximate a value for beta by looking at the plot of Ral in Hornresp. getting the horn length and mouth size approximately right should give a sensible value for beta to calculate the other horn parameters.


Edited by snowflake - 03 September 2020 at 1:10am
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Old Croc
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Points: 3443 		Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 02 September 2020 at 9:47pm
I know David McBean knows Kolcheck as he is cited as proof-reading his 2008 article on 'Horn Theory' in AudioExpress. Can his solution of reactance annulling be incorporated into Hornresp rather than Leach's?
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Points: 547 		Post Options Post Options   Thanks (0) Thanks(0)   Quote citizensc Quote  Post ReplyReply Direct Link To This Post Posted: 03 September 2020 at 11:30am
Thanks for the links snowflake!

I have been thinking about a horn design using the 15sw115, might try apply that paper to designing it.
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still trying to get my head round this but here is a possible design procedure:

decide on a mouth area, Sd, a horn cutoff frequency (Fc as Kolbrek calls it), and a horn length (approx a quarter wavelength of Fc)

choosing a value for T will then give you a value for St (and therefore compression ratio) and a Vb. decreasing T will increase the volume of the horn, and once it gets below about T=0.6 will also increase the Vb. So you can choose T to make sure that the total system volume and compression ratio are acceptable.

different values of T will give either high sensitivity, or higher efficiency and ripple.

Edited by snowflake - 23 May 2022 at 11:22am
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Points: 547 		Post Options Post Options   Thanks (0) Thanks(0)   Quote citizensc Quote  Post ReplyReply Direct Link To This Post Posted: 06 September 2020 at 3:53am
I am getting closer to understanding it I think but im not 100% there. 

Section 1-2: Just the intro and horn basics. 

Section 3 is not something I consider in the types of horns I design.

Section 4 is very interesting, im not sure I completely understand it but my current take is; if following the procedure from the Leach paper results in a small rear chamber and low T value, a higher T value should be specified then equation 16 should be used to find the optimal Cat for that T value. If you have already chosen a driver, you can then derive the optimal rear chamber volume from that Cat value. Figure 7 makes me think a T value of >0.5 is ideal.

Section 5, I think all that is trying to say is that is trying to say is magnitude of ripples is inversely proportionate to compression ratio, is that right? I already understood this just from playing in hornresp. 

6 I would only be interested in if my sims were showing excursion problems

7 is interesting but I already had the same ideas about what t/s parameters were important from my experience. 

8 outlines a procedure for designing a horn with lower cutoff, compression ratio and driver parameters. This may be very useful, I am going to make up a spread sheet and give it a go. 
 

Please correct me if anything I am saying here is wrong. 
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