Hmm, interesting. The transition from triangular to rectangular basically evolves through a widening trapezium (widening to reactangular). So basically we can take hornresp data and use that (and some spreadsheet math) to calculate the depth of the bend at each point. For each given expansion there will be a given bend, the remainder of the hornlength gives the height (and watch driver mounting).
I am going to see if I can work out a useful spreadsheet for this. Would be fun, also for new/custom fullrange designs. The 12" and/or 15"Fane fullrange drivers, with their massive rising treble, might be fun in something like this.
The new synthesis and fusion of Bruce Edgar's tractrix cone midrange horn and midbass J-horns.
(Although he is not a fan of fullrange drivers in front horns, I think.)
I made a quick sim for the 15" based on still poorly researched assumptions. It looks a bit like the Voigt HCH is roughly a 1/4th size 85Hz tractrix horn. Truncating it to Khorn throat-size and adding a Khorn-sized backchamber leads to a smooth hornresp sim extending to 1kHz (with directivity) and a -3dB lower cutoff around 50Hz. A lot lower with room gain and some backchamber tuning. This is worth exploring and fine-tuning.
I am going to see if I can work out a useful spreadsheet for this. Would be fun, also for new/custom fullrange designs. The 12" and/or 15"Fane fullrange drivers, with their massive rising treble, might be fun in something like this.
The new synthesis and fusion of Bruce Edgar's tractrix cone midrange horn and midbass J-horns.
(Although he is not a fan of fullrange drivers in front horns, I think.)
I made a quick sim for the 15" based on still poorly researched assumptions. It looks a bit like the Voigt HCH is roughly a 1/4th size 85Hz tractrix horn. Truncating it to Khorn throat-size and adding a Khorn-sized backchamber leads to a smooth hornresp sim extending to 1kHz (with directivity) and a -3dB lower cutoff around 50Hz. A lot lower with room gain and some backchamber tuning. This is worth exploring and fine-tuning.
In round numbers then:
~62 Hz
~832 Hz
~169 Hz
.....and if I did the math right will load to ~26 Hz in an ideal corner, so figure around 30-35 Hz in most rooms, which jives well with the 'drops an octave in a corner' ROT, i.e. ~31 Hz.
Hope you can create a nifty designer as an upgrade to the BIB's.
GM
~62 Hz
~832 Hz
~169 Hz
.....and if I did the math right will load to ~26 Hz in an ideal corner, so figure around 30-35 Hz in most rooms, which jives well with the 'drops an octave in a corner' ROT, i.e. ~31 Hz.
Hope you can create a nifty designer as an upgrade to the BIB's.
GM
I meant upgraded relative to the super simple, basic, BIB Excel calculator.
BL pipe horns are barely mid FI by today's standards, but I imagine his more complex horns are a major step up to his pipe horns or doubt he ever would have bothered
except as design exercises.
One can only wonder what 'full-range' speakers would be like today if he'd stepped out from 'conventional wisdom' and done a BIB with front loaded horn in lieu of his ~ 'textbook' floor loaded BLH.
GM
BL pipe horns are barely mid FI by today's standards, but I imagine his more complex horns are a major step up to his pipe horns or doubt he ever would have bothered
except as design exercises.
One can only wonder what 'full-range' speakers would be like today if he'd stepped out from 'conventional wisdom' and done a BIB with front loaded horn in lieu of his ~ 'textbook' floor loaded BLH.
GM
I meant upgraded relative to the super simple, basic, BIB Excel calculator.
Ah, I see. Let's figure out the maths/process blocks first. I have the blocks more or less defined and in place, but am struggling to find the relevant math. Or, the blocks process differently and I am not quite seeing the marriage of them.
Maybe I need to split this off to its own thread. Maybe not.
This is my thinking as well. I have built tractrix horns with calculated Fcs down to 90 Hz and the bigger the better. There is an increasing dynamic intensity, for which I have few other words to describe. But the longer ones were impractical, and suffered from reflections. The latter problem was minimized by going from 4-sided to 5-sided. But due to the length, the horns sticking out too far, I didn't pursue this. The HCH seems such a big fix to both issues (shallow and 3-sided through much of its expansion).
I haven't succeeded in turning my idea into math. And I haven't succeeded in explaining it to my wife, who helped my do the math for five-sided petal horns. (I love her.)
I remembered spending some time on scaling up horns in a spreadsheet and calculating new ones from formulas. If I did it right, I can conclude that a scaled up horn is the same shape of a properly calculated horn of the same dimensions.
So in partially denying defeat, I decided I can scale the Voigt horn home constructor's final bend.
Recalculating and re-deducing things, I think this cornerhorn has a 1/8th sized mouth, and a 60Hz expansion. I've been looking at what I can fit and I can scale the mouth up to about a 1/8th 50Hz tractrix horn for my Fane 15" fullrange drivers. In hornresp, bass extension is down to a full 50 Hz, directivity makes response flat up do above 1kHz where its response starts rising. Pretty cool. Interesting.
I like full treble, but the midrange is where we live""!
I remembered spending some time on scaling up horns in a spreadsheet and calculating new ones from formulas. If I did it right, I can conclude that a scaled up horn is the same shape of a properly calculated horn of the same dimensions.
So in partially denying defeat, I decided I can scale the Voigt horn home constructor's final bend.
Recalculating and re-deducing things, I think this cornerhorn has a 1/8th sized mouth, and a 60Hz expansion. I've been looking at what I can fit and I can scale the mouth up to about a 1/8th 50Hz tractrix horn for my Fane 15" fullrange drivers. In hornresp, bass extension is down to a full 50 Hz, directivity makes response flat up do above 1kHz where its response starts rising. Pretty cool. Interesting.
I like full treble, but the midrange is where we live""!
Correct, a 90x90x90 corner space = 1/8th = 4x reduction, hence a corner horn's truncation ratio. Historically, tuning = Fs = flare frequency. Lacking the math skills, I design a full size horn and cut out the section that best 'fits' the driver's size, specs.
Indeed! The pioneers considered 50-11,000 Hz sufficient for 'high fidelity' full size orchestra, large vocal groups reproduction with only the 250-2500 Hz telephone BW + an octave extension [basically AM radio BW] each side being critical other wise.
GM
Indeed! The pioneers considered 50-11,000 Hz sufficient for 'high fidelity' full size orchestra, large vocal groups reproduction with only the 250-2500 Hz telephone BW + an octave extension [basically AM radio BW] each side being critical other wise.
GM
I propose a 3 step design process for the horn of the Home Constructors (I am not interested at the bass pipe at this time, to be honest).
1. Scale mouth and bend based on required mouth size.
2. Scale the throat to the required size.
3. calculate the tractrix expansion between the throat section and the mouth section.
Step 1 is not that special. Step 3 is easy. Step 2 is more interesting, because this is where the precise coupling and aligning happens.
After actually calculating the area of the baffle-cutout from the drawings, it turns out to be the average size of a 6" driver (136,3 cm^2). So probably equal to Sd. It fires into a reflector, which bends the horn up into the middle segment. The area at the transition from reflector to middle segment is 1.1x the throat area. So once a driver has been chosen, Sd gives both throat area and the footprint of the horn.
So how to scale the mouth is known, and the throat and first bit of horn as well. Step 3, to calculate remaining/missing tractrix portion is now feasible.
My wife is on board now, too. She thinks they look a bit weird, but everytime I wanted to try out something weird, she liked the end result.
1. Scale mouth and bend based on required mouth size.
2. Scale the throat to the required size.
3. calculate the tractrix expansion between the throat section and the mouth section.
Step 1 is not that special. Step 3 is easy. Step 2 is more interesting, because this is where the precise coupling and aligning happens.
After actually calculating the area of the baffle-cutout from the drawings, it turns out to be the average size of a 6" driver (136,3 cm^2). So probably equal to Sd. It fires into a reflector, which bends the horn up into the middle segment. The area at the transition from reflector to middle segment is 1.1x the throat area. So once a driver has been chosen, Sd gives both throat area and the footprint of the horn.
So how to scale the mouth is known, and the throat and first bit of horn as well. Step 3, to calculate remaining/missing tractrix portion is now feasible.
My wife is on board now, too. She thinks they look a bit weird, but everytime I wanted to try out something weird, she liked the end result.
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