Folded horn for Tannoy?

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Recently I decided to build a back loaded horn enclosure for my Tannoy monitor 15". I found the original plan for it, the so called R-GRF, but since the overall height is 40inches only, the driver is located lower than the ideal position. So I would like to ask if it is possible to make the cabinet taller so to expand the horn even more in order to achive the ideal position and also to add a bit more length to the horn(also a reduction of enclosure width would be more than desired). If this is a good plan, how can I change the design? Moreover can anybody help me to enter the parameters to hornresp so to take an idea of its respoce?

Thanks in advance for any help
 

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I wouldn't worry to much about exact figures for increasing the length of the horn. Horn enclosures made from flat panels bare so little resemblence to the exponential/tractrix flare that they are supposed to follow (and this is certainly true of the one in your drawing) that attempting to predict behaviour is near impossible. Add to this the strong room/position dependence of domestic (too small) horns.

The design of the throat end of the horn is very important but this can stay as it is.
 
Generally, I agree with Richard's comments above. Build the box, and put it on a temporary stand, adjusting the height slightly up and down until you get the response you're looking for. Depending on the room it can vary quite noticably.

PS: I'm looking at building something similar for my lone 12" Red and using it for my bass guitar.
 
personally i trust my own design compared to tens of years old plans based on standard curves and rules of thumb+ some luck.

it depends what the intended use is

i just suggest that a modern horn design would perhaps be more better.

also the seperate sub box provides versatility of placement of the MF and HF

i dont like the fullrangish -style myself,i would like to audition as many as i can however there arent any around here.

:)
 
Alchemy!

Dear all, first of all the the R-GRF is definitely not the best horn designed by tannoy as its a simple folded horn very compromised in all parameters of the disign and got nothing to do with the original GRF. Second, as far as Mikee's design although good is out of the question as my drivers are concentrics meaning have to be mounted in front in order for the high frequency unit to radiate corectly. I cannot believe there is no math justification in building a horn and most horns are calculated by rule of thumb, anyway I keep searcing the matter but it beggins to seem like alchemy to me, probanly I will have to go the trial and error route. :bawling:

Any more ideas?
 
There is plenty of maths/ equations etc. that can be used to produce very accurate bass horn designs. The problem is if you build a horn strictly according to the results you won't be able to get it in the room which is why all commercial domestic designs are severely compromised.

A few years ago I designed and built a pair of horns for some Lowther PM6Cs, similar to the Bravura Brio. I like this design because the mouth of the horn is at the back of the enclosure and uses the corner of the room to approximate the profile and extend the length of the horn. The speakers worked very well and were so sensitive they could be driven from a pre-amp!

Calculating a flare for the horn is not difficult once the throat has been specified the question then is; how big do you want the enclosures to be? bearing in mind that the area of the mouth of the horn increases exponentially with length.

My domestic circumstances have change and I don't use my horn speakers anymore (they,ve been displaced by cushions) but they were impressive.

The only notion that bothers me about back-loaded horns is that the bass is several metres behind the rest of the music.
 
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