Folded horn for Tannoy?

panos29 · 13th October 2003, 08:22 AM

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

Tazzy · 13th October 2003, 04:43 PM

Wouldn't it be much easier to add a box underneat to fill with sand or something? That way you don't have to recalculate the design.

panos29 · 13th October 2003, 06:20 PM

That exactly was my initial thought, however, after lots of horn reading I found that I can gain something by increasing the height yhus the horn length in addition to the elevation of the cone? Any ideas?

Richard C · 13th October 2003, 06:48 PM

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.

Brett · 13th October 2003, 08:41 PM

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.

mikee12345 · 15th October 2003, 07:36 PM

what about this i drew up the first CAD diagram yesterday.

www.geocities.com/sc00byd0159/40hzbasshorn.html

Nelson Pass · 15th October 2003, 08:31 PM

Just a comment that the GRF is supposedly the best horn
Tannoy every built, which is saying a lot. You might consider
building it as originally designed.

Brett · 15th October 2003, 08:33 PM

Mike,

What about the concentric HF driver in the Tannoy?

mikee12345 · 16th October 2003, 02:08 AM

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.

panos29 · 16th October 2003, 07:09 AM

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.

Any more ideas?

16th October 2003, 07:09 AM	#10
panos29 diyAudio Member Join Date: Dec 2001 Location: ATHENS, GREECE	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. Any more ideas?

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13th October 2003, 04:43 PM	#2
Tazzy diyAudio Member Join Date: Jul 2002 Location: Netherlands	Wouldn't it be much easier to add a box underneat to fill with sand or something? That way you don't have to recalculate the design.

13th October 2003, 06:20 PM	#3
panos29 diyAudio Member Join Date: Dec 2001 Location: ATHENS, GREECE	That exactly was my initial thought, however, after lots of horn reading I found that I can gain something by increasing the height yhus the horn length in addition to the elevation of the cone? Any ideas?

13th October 2003, 06:48 PM	#4
Richard C diyAudio Member Join Date: Jul 2003 Location: Nottingham, England	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.

13th October 2003, 08:41 PM	#5
Brett diyAudio Member Join Date: Jan 2002	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.

15th October 2003, 07:36 PM	#6
mikee12345 diyAudio Member Join Date: Nov 2002 Location: NZ	what about this i drew up the first CAD diagram yesterday. www.geocities.com/sc00byd0159/40hzbasshorn.html

15th October 2003, 08:31 PM	#7
Nelson Pass The one and only Join Date: Mar 2001	Just a comment that the GRF is supposedly the best horn Tannoy every built, which is saying a lot. You might consider building it as originally designed.

15th October 2003, 08:33 PM	#8
Brett diyAudio Member Join Date: Jan 2002	Mike, What about the concentric HF driver in the Tannoy?

16th October 2003, 02:08 AM	#9
mikee12345 diyAudio Member Join Date: Nov 2002 Location: NZ	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.

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