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Horn-Loaded Speakers
Topic: What are the effects of back chamber volume for mid-bass horns?

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Posted by rickmcinnis on 09-27-2013
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Romy,

Is there a consistent effect from too large/too small and how is it analyzed? 

 Working on a new horn that I had turned by a fellow in Hungary and have made my back chamber so that I can easily
 manipulate the volume but have no idea of what to expect.

 Knowing you have gone through the process a number of times I am hoping you will be willing to give me some guidance.

Audible clues? or does one need to rely on measurements to get in the range?
 I am still in the process of getting the thing ready so I have no idea what it sounds like at the moment.  Starting off with HORNRESPONSEcalculated value which is based on driver manufacturers specs instead of measuring for myself which probably makes the value next to useless.

 Using the B&C 12 inches driver as recommended by John Inlow.  Unobtainable drivers like your favored FANES would have been tried if ...
Yes, I am going with more of an EDGAR type set-up than A BESNOW set-up since that is the best I can do.  This round horn will replace my EDGAR 75 hz square hoen with the EV driver.
Posted by Romy the Cat on 09-27-2013
fiogf49gjkf0d

 rickmcinnis wrote:
Is there a consistent effect from too large/too small and how is it analyzed?

 Working on a new horn that I had turned by a fellow in Hungary and have made my back chamber so that I can easily
 manipulate the volume but have no idea of what to expect.

 Knowing you have gone through the process a number of times I am hoping you will be willing to give me some guidance.

There was an old thereds that will do it:

http://www.goodsoundclub.com/Forums/ShowPost.aspx?PageIndex=1&postID=2991#2991

http://www.goodsoundclub.com/Forums/ShowPost.aspx?PageIndex=1&postID=4421#4421

 rickmcinnis wrote:
Audible clues? or does one need to rely on measurements to get in the range?
 I am still in the process of getting the thing ready so I have no idea what it sounds like at the moment.  Starting off with HORNRESPONSE calculated value which is based on driver manufacturers specs instead of measuring for myself which probably makes the value next to useless.
Audible clues are an interesting subject. I would discard the HORNRESPONSE. That is irrelevant crap. You need to look at the max bottom EQ and for the character of lower octave of your horn. it has to have a “specials” slowness but able to play high transient if music calls upon it. It has to be not suffocated tonally. All of it very hard to explain in world and need to be once demonstrated and you will know what and how to listen. You can very precisely offset your throat resonance with back chamber but ironically the last little 1 Hz of precision do impacts sound very audibly, the larger horn the more impact. 
 rickmcinnis wrote:
Using the B&C 12 inches driver as recommended by John Inlow.  Unobtainable drivers like your favored FANES would have been tried if ...
I do not think that Fanes are unobtainable and I do not know the B&C 12.
 rickmcinnis wrote:
Yes, I am going with more of an EDGAR type set-up than A BESNOW set-up since that is the best I can do.  This round horn will replace my EDGAR 75 hz square hoen with the EV driver.
The Bruce’s approach is to use a large throat, the smaller throat the more EQ you had and the more effective would be the influence of back chamber. If you use too large driver over smaller throat then an exercise compression might easy up your tonal quality of the driver.

The Cat
Posted by rickmcinnis on 09-27-2013
fiogf49gjkf0d
Sorry I did not find that first link on my own.
That is an elegant way to find the best volume.  It should have been obvious which is what makes it elegant
I was not able to find any FANE's but then I likely have no idea where to look.  Would you offer a suggestion of a good place?
This horn has a six inches throat with a concave chamber between the throat and the driver's mounting.  Cone is nine inches in diameter.
Approx 36 inches in length - mouth is approx 26 inches. 
I did not think you would have had any reason to be familiar with the B&C.  It seemed like a good one to try.  I know nothing about it either.
THANKS very much for the advice.  Now I know where to begin.  (The Cat knows ...)

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