GM said:
Thanks, ... I'm off to go buy some 1/2" MDF and build this one. .. I have a pair of drivers lying unused and by my calculations, I should be able to build a fairly compact TH in half a sheet with minimal bracing, given the compact dimensions (~ 8" x 8 " x 4 ft )
If it doesn't work out, I'll use the rest of the sheet and build a compact isobaric subwoofer for my car.
I wonder what I'll screw up this time, ..
And the proposed plan , .. I'll start glue-up tomorrow, .. will probably have to add an access cover on the port panel... Bracing will be added, as suggested by GM.
I'm mainly interested in measuring the effects of stuffing on response, .. and to see what kind of cone motion I get, as well as amount of low bass. If the expt, fails, .. it won't be the first time ..
The cone on my karlson K-15 hardly moves,no matter what I throw at it, . and I noticed the same a few years ago when I built a tapped line with a fostex full range driver.
I'm mainly interested in measuring the effects of stuffing on response, .. and to see what kind of cone motion I get, as well as amount of low bass. If the expt, fails, .. it won't be the first time ..
The cone on my karlson K-15 hardly moves,no matter what I throw at it, . and I noticed the same a few years ago when I built a tapped line with a fostex full range driver.
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Hi guys, I have a question 
)
I've read the whole TH Thread but nowhere saw mentioning the extension of smaller drivers.
I have a 'refrigerator TL 12" sub in the corner that i would like to replace since it is too boomy. However i also would like to use more subs in the room to smooth out my horrible room (<200sq.ft.).
I want maximum extension and effortlessness of bass production. Right now I really enjoy OB Bass down to 30hz but its somewhat soft and doesn't have enough 'slam' for drums and HT.
If i use 2-3 subs with 8-10" drivers will they reach just as low and play with the same authority as one 12" driver?
How should i be selecting those drivers since there are not many that reach down to 20hz but for TH we are selecting drivers that have Fs=35Hz so i guess "IT WILL WORK". WILL IT?
I could position them around the room (in the wall-ceiling corners). My main speakers have 15" woofers and midranges on OB, so 8" SUBS seem kind of funny. Maybe i just have to get used to it.
Thanks I'm really excited i will finally build something again after couple of years of having a life.
)I've read the whole TH Thread but nowhere saw mentioning the extension of smaller drivers.
I have a 'refrigerator TL 12" sub in the corner that i would like to replace since it is too boomy. However i also would like to use more subs in the room to smooth out my horrible room (<200sq.ft.).
I want maximum extension and effortlessness of bass production. Right now I really enjoy OB Bass down to 30hz but its somewhat soft and doesn't have enough 'slam' for drums and HT.
If i use 2-3 subs with 8-10" drivers will they reach just as low and play with the same authority as one 12" driver?
How should i be selecting those drivers since there are not many that reach down to 20hz but for TH we are selecting drivers that have Fs=35Hz so i guess "IT WILL WORK". WILL IT?
I could position them around the room (in the wall-ceiling corners). My main speakers have 15" woofers and midranges on OB, so 8" SUBS seem kind of funny. Maybe i just have to get used to it.
Thanks I'm really excited i will finally build something again after couple of years of having a life.
Hallo,
i try the smallest TH,
SUB FANFARE,
in order of the max SPL,~32 Hz,
combine 8+8 double horns,
only 15 cm deep, at the Wall,
or as block in a corner,
16 Horn parts are not small,
and a lot of building,
but invincible.
super IMP by membran movement cross setting and
basshorn mouth distance
i try the smallest TH,
SUB FANFARE,
in order of the max SPL,~32 Hz,
combine 8+8 double horns,
only 15 cm deep, at the Wall,
or as block in a corner,
16 Horn parts are not small,
and a lot of building,
but invincible.
super IMP by membran movement cross setting and
basshorn mouth distance
zobsky said:
Hmm, maybe I'm missing something, but your dims neither matches up to your proposed design or to using 0.5" thick material. Also, there's currently no way to sim the reflection from the driver to a second closed end and back to the terminus. My SWAG is it will cause some peaking on the low side (FLp), in theory requiring more stuffing, though the vent area is > S4, so it may balance out.
Anyway, looking forward to measured results.
Yeah, the K15 is an interesting take on a BP and all its resonant chambers does a good job at providing a ~balanced acoustic load to both sides of the diaphragm over a fairly wide BW in much less bulk than the contemporary Jensen Transflex tapped pipe (TL) that virtually no one today knew about until TD rediscovered the concept.
GM
Well, I upsized / tweaked it slightly when I drew up the sketch (in part for slightly better efficiency and in part to allow me to add some bracing). I'll post the updated hornresp data when I get home (computer is currently sick with a virus, need to deal with that first)
Regardless, I haven't sealed it up yet or finalized the amount of bracing but from first impressions, I think this one is headed to the dumpster, sooner or later, unless something improves (read on)
Preliminary testing involved placing the cabinet open end down on the carpet ( and having someone sit on it ) to provide a temporary seal. I seemed to be hitting or nearing the limits of the drivers excursion somewhere around 30 Hz, as GM predicted . Stuffing seemed to even out the bass a little bit . I was maxing out the gain on a 100 W / 4 ohm sub amplifier at that point, so I'd estimate somewhere around 50 W input or so. Bass is useable to about 30 Hz in room, and I can sense output down to the high 20 Hz region.
My other main gripe is that this particular design is too quiet (8 ohm impedance is probably to blame a good deal),.. but even otherwise, with the gain on the preamp and sub amp maxed out , it couldn't keep up at all with my OB line arrays, even at below normal levels. I finally had to substitute in a dinky little satellite speaker to even get any subjective impressions. This is compared to a Table Tuba loaded with an 8" MCM which doesn't even begin to sweat at that point. However, different animals so , .....
I'm hoping that sealing up this box will eliminate any leakage and allow me to truly evaluate the potential of this one, esp. with regards to excursion. If the excursion issue is solved, I can use one of solid state grunt amplifiers to generate more output
That apart, the bass seems to be non-resonant and smooth ,. both good things
I'll post some SPL graphs and WT3 impedance graphs with / without stuffing soon, so we can get an idea of how the final design corroborates with the hornresp data.
Give me some time to get back with some data.
Regardless, I haven't sealed it up yet or finalized the amount of bracing but from first impressions, I think this one is headed to the dumpster, sooner or later, unless something improves (read on)
Preliminary testing involved placing the cabinet open end down on the carpet ( and having someone sit on it ) to provide a temporary seal. I seemed to be hitting or nearing the limits of the drivers excursion somewhere around 30 Hz, as GM predicted . Stuffing seemed to even out the bass a little bit . I was maxing out the gain on a 100 W / 4 ohm sub amplifier at that point, so I'd estimate somewhere around 50 W input or so. Bass is useable to about 30 Hz in room, and I can sense output down to the high 20 Hz region.
My other main gripe is that this particular design is too quiet (8 ohm impedance is probably to blame a good deal),.. but even otherwise, with the gain on the preamp and sub amp maxed out , it couldn't keep up at all with my OB line arrays, even at below normal levels. I finally had to substitute in a dinky little satellite speaker to even get any subjective impressions. This is compared to a Table Tuba loaded with an 8" MCM which doesn't even begin to sweat at that point. However, different animals so , .....
I'm hoping that sealing up this box will eliminate any leakage and allow me to truly evaluate the potential of this one, esp. with regards to excursion. If the excursion issue is solved, I can use one of solid state grunt amplifiers to generate more output
That apart, the bass seems to be non-resonant and smooth ,. both good things
I'll post some SPL graphs and WT3 impedance graphs with / without stuffing soon, so we can get an idea of how the final design corroborates with the hornresp data.
Give me some time to get back with some data.
Stuffed vs unstuffed impedance.
The curves look too smooth to be true. I verified the results with both ARTA and WT3 with similar results. I've measured a few horns before and they don't look anything this smooth.
I'm guessing sealing the box against the carpet is creating a highly leaky situation so I'm measuring something more akin to a lossy / aperiodic enclosure. Time to add a few braces and seal her up before reevaluate / remeasure .
The curves look too smooth to be true. I verified the results with both ARTA and WT3 with similar results. I've measured a few horns before and they don't look anything this smooth.
I'm guessing sealing the box against the carpet is creating a highly leaky situation so I'm measuring something more akin to a lossy / aperiodic enclosure. Time to add a few braces and seal her up before reevaluate / remeasure .
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sealed it up. MUCH better. I still don't think it's going to displace my other horn (yet) but not bad at all this time. Bass is solid to 30 - 35 Hz and seems to taper off below that. Excursion is better controlled than before I sealed up the top of the "coffin"
I haven't had the time to play with stuffing (I'm curious and will try that soon as time permits) but here's an impedance plot. As soon as I get the chance to recover the orig. hornresp. data, I'll post the predicted hornresp impedance plot too.
I haven't had the time to play with stuffing (I'm curious and will try that soon as time permits) but here's an impedance plot. As soon as I get the chance to recover the orig. hornresp. data, I'll post the predicted hornresp impedance plot too.
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AllenB said:
Not sure either is anywhere close to optimal. At least the mouth at the floor-wall boundary gives you some 1/4 space gain but the whole concept of positioning the opening at the "center" could lead to uneven response.
For a more confusing answer (is that possible?) , read http://www.stereophile.com/interviews/105villchur/index3.html or search for the Allison effect on google.
For example, .. http://www.harbeth.co.uk/usergroup/showthread.php?p=3822