Top is not as extended as FF125 or FE126. FE108 are noted for their midrange -- but are really getting long of toothwith more modern drivers eclipsing them.
dave
Planet10,
Regarding the B200's and doubling: Probably so, but I meant just to fit physical dimension of driver in. If the throat area was matched the B200's Sd, would that not be sufficient? Would the larger Vas require a change in the driver chamber volume beyond the 640 cubic inches ( 8 x 8 x 10 inches)? I personally think going with anything larger than a 5 inch driver is missing the point of the Cornu's ability to provide more than enough bass but still have the smaller driver for good high frequency and the wider dispersion they provide compared to an 8 in full range with their 'beaming' issues. The FF125ken's that Cal and now, Jim will be using, how much better is it than stock Fostex's? I am interested but have no idea what the extra treatments sound like.
Thanks,
Xrk971
Regarding the B200's and doubling: Probably so, but I meant just to fit physical dimension of driver in. If the throat area was matched the B200's Sd, would that not be sufficient? Would the larger Vas require a change in the driver chamber volume beyond the 640 cubic inches ( 8 x 8 x 10 inches)? I personally think going with anything larger than a 5 inch driver is missing the point of the Cornu's ability to provide more than enough bass but still have the smaller driver for good high frequency and the wider dispersion they provide compared to an 8 in full range with their 'beaming' issues. The FF125ken's that Cal and now, Jim will be using, how much better is it than stock Fostex's? I am interested but have no idea what the extra treatments sound like.
Thanks,
Xrk971
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I was/would be very interested in how you get along if you proceed, i have a personal set of B200 i have no interest in putting into an OB.
The guy from Australia with the C-Horn was pleased with the B200 in it -- something that was unexpeced, so who knows. It is a smaller horn than a 4x4x 2/3 foot Cornu would be.
dave
I would start small and cheap: make it 20 in square (so you can use foam core board stock) and use a Vifa TC9FD driver. It is a quick build as there are no heavy tools, saws, dust, etc. You will gain some experience with the ins and outs. Then go for the bigger one with premium drivers and real wood faces. If you are like me, you will be blown away by the sound of the smaller TC9FD's in the foam core enclosures. These will be decorated and become my main listening speakers for music. They are that good. Not bad for a $30 set of speakers.
Sd should have nothing to do with it. It has been historically used forTLs & horns, andunfortunately because of that Martin used it as a unit of area inhis model which confuses things more.
dave
Besides the EnABL extracting more DDR out of the driver, other treatments pre & post EnABL help tame some of the driver's rough edges making its response much smoother.
A set of FF85wKeN in your smaller version would be very interesting.
dave
If not Sd, what should we scale the horn channel depth and throat opening with, Vas? If you make throat area smaller than Sd, you would be constricting pressure and increasing velocity of air due to mass conservation. Wouldn't this reduce the horn's efficiency?
There is a relation between Vas, Q, volume of the air cavity, and the throat area that determine the low pass function. Youdon't want too much HF coming out the horn mouth
Further. the difference in path length between the direct radiation and that from the back of the driver to your ear should be an odd number of half wavelengths of the nominal f3 of the acoustic LP of the throat/air cavity.
Efficiency (horn gain) is not high on the list of parameters to design for -- more of interest in front horns. Cal's build ilustrate that as long as you have enuff or more than you need horn gain can be adjusted with stuffing. You want the fall-off of the driver & baffle-step losses to be compensated for by the gain of the horn. With no baffle steptodeal with this horn needs less gain, the big bonuses coming from the ability to get lower bass out of asmall driver, and reduction in excursion at those frequencies.
dave
Further. the difference in path length between the direct radiation and that from the back of the driver to your ear should be an odd number of half wavelengths of the nominal f3 of the acoustic LP of the throat/air cavity.
Efficiency (horn gain) is not high on the list of parameters to design for -- more of interest in front horns. Cal's build ilustrate that as long as you have enuff or more than you need horn gain can be adjusted with stuffing. You want the fall-off of the driver & baffle-step losses to be compensated for by the gain of the horn. With no baffle steptodeal with this horn needs less gain, the big bonuses coming from the ability to get lower bass out of asmall driver, and reduction in excursion at those frequencies.
dave
Hold on there Billy, guys like me find the top end rather restricted. The up side is the lack of listening fatigue. I could listen to these at a decent volume all night.
OK, so I added a little stuffing to the throats and that really helped with the bass horny hump above 100 Hz. I also placed them 12" away from the wall and that was another plus. I am thinking that further stuffing of the throats and returning them closer to the wall will be the cat's meow. I'll find out another day as I have to wrap it up but the improvements were huge, heck even SWMBO took an interest which is almost unheard of. I listened to my regular test tunes and then I put on Jimmy...
That's where I've been for the last couple hours.
I don't know what to say, I'm near speechless. For those who know me that's something they wouldn't believe for a second.
Cheers.
That's where I've been for the last couple hours.
I don't know what to say, I'm near speechless. For those who know me that's something they wouldn't believe for a second.
Cheers.
Yeah I see that, at least when the length of adjacent horns are the same. Need to see if that's true for the horn's full length.. Some sticks across the unbraced mouth area would be a good refinement later.
The 1/2" foam core, and the door skin suggestions were for the fronts and backs, instead of the 1/4" ply Cal used. They would be lighter, and I was thinking the 1/4" is maybe more than needed. I believe that the door skins are 2 ply 1/8" ply in effect, and as mentioned, appearance was part of it. I've worked with coroplast and it's not stiff at all, I think a lot less stiff than 1/4" foam core, so I wouldn't suggest it for anything!
Um the double thick version with center divider could just have higher, deeper (taller?) walls right, except they would be less stiff, so if we use a stiffer material the center wall might not be necessary, OR if Cal is right and the forces on each side aren't necessary then they don't have to be stiffer..
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I am considering using a paper and glue laminate to stiffen the outside of the mouth where it runs parallel to the facers. I am wondering if that will dampen the potential resonance better? Could be wrong but...
Sorry Mark, I have to disagree. I too, am familiar with the Coroplast and I think once you work with the foam core you will understand. You can't really score and bend it the same way. I thought it was strange when xrk suggested inside scoring but all makes sense when you do some experimenting. Try both and see what you think.
You don't have any dollarama or other dollar stores there? I found "poster" foam board at $1.25 a sheet 20x30 in.