backloaded horn eh? Hmmmm...
I think I'm probably going to just go with the Tuba36 slim horizontal baffle as bill suggested and be over with it.
the way I see it is this.... my ears can hear only down to ~24hz so I want my sub to be as loud and clean as possible form there on up. Having extension down down below is really nice for like .01% of music/movies, but for everything else it just doesnt do anything. I really want to horn load the tumult. I'm tired of that lame 88db efficiency in a vented box. I dont care how deep it goes....
I think I'm probably going to just go with the Tuba36 slim horizontal baffle as bill suggested and be over with it.
the way I see it is this.... my ears can hear only down to ~24hz so I want my sub to be as loud and clean as possible form there on up. Having extension down down below is really nice for like .01% of music/movies, but for everything else it just doesnt do anything. I really want to horn load the tumult. I'm tired of that lame 88db efficiency in a vented box. I dont care how deep it goes....
BTW the MCM will be here tuesday so I'll be done with the AutoTuba then.
And with regards to the Tumult horn, Floorspace isn't a concern here. As long as it can fit through the door and I can move it with the help of a buddy or two, I'm game. I have very cool parents. I'm sure some of you are jealous that your parents or wives dont let you get away with such things, but what can I say... I'm lucky
And with regards to the Tumult horn, Floorspace isn't a concern here. As long as it can fit through the door and I can move it with the help of a buddy or two, I'm game. I have very cool parents. I'm sure some of you are jealous that your parents or wives dont let you get away with such things, but what can I say... I'm lucky
GM,
so you are suggesting either use the Tumult in a bandpass box for say 10 - 40 Hz or using it in a real loaded horn. If the latter, what kind of tuning would you go for and what kind of size would be necessary to achieve it?
This is not an idea I've considered for typical subwoofer drivers. If I understand correctly, it will extend the useable response downward rather than increase overall efficiency.
Do you think it's worth the extra size of the horn version when operating down that low?
so you are suggesting either use the Tumult in a bandpass box for say 10 - 40 Hz or using it in a real loaded horn. If the latter, what kind of tuning would you go for and what kind of size would be necessary to achieve it?
This is not an idea I've considered for typical subwoofer drivers. If I understand correctly, it will extend the useable response downward rather than increase overall efficiency.
Do you think it's worth the extra size of the horn version when operating down that low?
Greets!
Correct. Well, like most things, it depends. 😉 Since it has so much power handling/Xmax, you can tune it above Fs and EQ it, or since rooms tend to become sieves below some frequency, increasingingly 'bleeding off' the LF, tuning it somewhat below Fs will offset this somewhat. It has the advantage of better damping Fs, which will lower the system Qtc.
Size wise, it depends on the 'M' factor. In the good 'ol days the basshorn had to play up to several hundred Hz to keep the XO component values/size acceptable, so large, fairly fast expanding exponentials were used to keep length down at reasonably low distortion. Today this is moot and if the XO point is kept below ~120 Hz, our hearing acuity has rolled off enough that we're more interested in a good blend amplitude and damping wise than how low the distortion is. Indeed, most folks prefer some distortion down low so that it doesn't sound so 'dry'.
Anyway, ideally a BLH needs to be a very low flare rate hyperbolic, so a conical expansion is 'close enough' since it's going to be truncated well before the 'ideal' mouth expansion begins in earnest. The Tumult's mass corner is ~106 Hz, so assuming a ~aneochoic flat response to 16 Hz and an 80 Hz/4th order XO.........
L = ~300"
St = ~33"^2
Sm = ~1143"^2
Vb = ~1.02 ft^3
Excluding dividers/driver, net Vb = ~80.32 ft^3 if I did the math right, so won't be particularly cheap to build, and having such an acoustically small mouth will cause some out of BW 'ringing' that an XO won't attenuate, so either flaring the mouth or heavily damping its perimeter may be required, and of course this thing needs to be incredibly rigid.
As you shorten it Fc/gain goes up, smoothing the response a bit, but because it's getting progressively underdamped with increasing Fc, transient response suffers, while increasing it lowers Fc/gain, smoothing it, but becomes increasingly overdamped, improving transient response.
FWIW, I designed a modded 'Voigt' style pipe tuned to 19 Hz awhile back for someone locally, but AFAIK he's never built it so......
L = 240"
So = 2.694"^2 (actually terminates to a point)
SL = 464.533"^2
zdriver = 144"
vent = 12" dia. x 10" long
stuffing density = ~0.25 lbs/ft^3, though if the room 'bleeds off' too much extreme LF, then reduce it to get some peaking at Fp and/or tune it lower.
It 'only' has a ~flat aneochoic 90 dB sens. down to Fs with a ~16 Hz F3, and at ~22.55 ft^3 net definitely not small, but at least manageable enough to be a bit more flexible WRT shape/positioning than the BLH, which ideally needs to be a 'W' fold spread across the floor.
Whether either of these designs is justifiable depends on your available space, budget, performance goals. I've experienced a very efficient basement sized expo basshorn and it's quite thrilling, but so is a bunch of fairly cheap, low Qtc sealed subs spread across the front wall/floor junction to create an apparent 'wall of sound' if BW limited with an 80 Hz/4th order XO.
GM
GM
Correct. Well, like most things, it depends. 😉 Since it has so much power handling/Xmax, you can tune it above Fs and EQ it, or since rooms tend to become sieves below some frequency, increasingingly 'bleeding off' the LF, tuning it somewhat below Fs will offset this somewhat. It has the advantage of better damping Fs, which will lower the system Qtc.
Size wise, it depends on the 'M' factor. In the good 'ol days the basshorn had to play up to several hundred Hz to keep the XO component values/size acceptable, so large, fairly fast expanding exponentials were used to keep length down at reasonably low distortion. Today this is moot and if the XO point is kept below ~120 Hz, our hearing acuity has rolled off enough that we're more interested in a good blend amplitude and damping wise than how low the distortion is. Indeed, most folks prefer some distortion down low so that it doesn't sound so 'dry'.
Anyway, ideally a BLH needs to be a very low flare rate hyperbolic, so a conical expansion is 'close enough' since it's going to be truncated well before the 'ideal' mouth expansion begins in earnest. The Tumult's mass corner is ~106 Hz, so assuming a ~aneochoic flat response to 16 Hz and an 80 Hz/4th order XO.........
L = ~300"
St = ~33"^2
Sm = ~1143"^2
Vb = ~1.02 ft^3
Excluding dividers/driver, net Vb = ~80.32 ft^3 if I did the math right, so won't be particularly cheap to build, and having such an acoustically small mouth will cause some out of BW 'ringing' that an XO won't attenuate, so either flaring the mouth or heavily damping its perimeter may be required, and of course this thing needs to be incredibly rigid.
As you shorten it Fc/gain goes up, smoothing the response a bit, but because it's getting progressively underdamped with increasing Fc, transient response suffers, while increasing it lowers Fc/gain, smoothing it, but becomes increasingly overdamped, improving transient response.
FWIW, I designed a modded 'Voigt' style pipe tuned to 19 Hz awhile back for someone locally, but AFAIK he's never built it so......
L = 240"
So = 2.694"^2 (actually terminates to a point)
SL = 464.533"^2
zdriver = 144"
vent = 12" dia. x 10" long
stuffing density = ~0.25 lbs/ft^3, though if the room 'bleeds off' too much extreme LF, then reduce it to get some peaking at Fp and/or tune it lower.
It 'only' has a ~flat aneochoic 90 dB sens. down to Fs with a ~16 Hz F3, and at ~22.55 ft^3 net definitely not small, but at least manageable enough to be a bit more flexible WRT shape/positioning than the BLH, which ideally needs to be a 'W' fold spread across the floor.
Whether either of these designs is justifiable depends on your available space, budget, performance goals. I've experienced a very efficient basement sized expo basshorn and it's quite thrilling, but so is a bunch of fairly cheap, low Qtc sealed subs spread across the front wall/floor junction to create an apparent 'wall of sound' if BW limited with an 80 Hz/4th order XO.
GM
GM
I wish I knew as much as you GM.....
But anyways thanks for the TL design.... I may build it sometime and if I do I'll surely let you know of the results.
Quick question for you GM....
Do you think I will be happy with the results if I build the Tuba36 slim horizontal baffle version?
But anyways thanks for the TL design.... I may build it sometime and if I do I'll surely let you know of the results.
Quick question for you GM....
Do you think I will be happy with the results if I build the Tuba36 slim horizontal baffle version?
The tuba subs are a good compromised design!
That means that with the corners you have to cut when trying to fit a horn into a realistic space it still performs. If you want to model a horn loudspeaker you can download the program called hornresponse. Take a cue from Bill's folding geometry. He didn't come up with it. It is in public domain. So if you designed one and folded it the same way you could end up with another good horn design.
If you wanted more low end you would have to do two things. THey both will drastically enlarge the size of the enclosure. Make it longer and make the overall taper larger.
Now I would say that the biggest design work that Bill did went into shrinking it down and still getting decent performance. The Hornresponse program is great for designing a what if scenario. Design one in horn response and start shortening it. Check the response. Downsize the mouth and check the response. I think you get the idea. Then bite the bullet. Either build Bill's design or if you feel that you have noodled around enough build your own.
Mark
That means that with the corners you have to cut when trying to fit a horn into a realistic space it still performs. If you want to model a horn loudspeaker you can download the program called hornresponse. Take a cue from Bill's folding geometry. He didn't come up with it. It is in public domain. So if you designed one and folded it the same way you could end up with another good horn design.
If you wanted more low end you would have to do two things. THey both will drastically enlarge the size of the enclosure. Make it longer and make the overall taper larger.
Now I would say that the biggest design work that Bill did went into shrinking it down and still getting decent performance. The Hornresponse program is great for designing a what if scenario. Design one in horn response and start shortening it. Check the response. Downsize the mouth and check the response. I think you get the idea. Then bite the bullet. Either build Bill's design or if you feel that you have noodled around enough build your own.
Mark
Greets!
You're welcome!
Study/experiment periodically for ~52 yrs like I have and with the powerful tools available today/future you'll probably know so much more than I'll ever know that in retrospect I'll seem like a rank newbie, especially if you're better at math/computers than me.
Not being familiar with either the design or what performance you expect of it, don't have a clue.
GM
You're welcome!
Study/experiment periodically for ~52 yrs like I have and with the powerful tools available today/future you'll probably know so much more than I'll ever know that in retrospect I'll seem like a rank newbie, especially if you're better at math/computers than me.
Not being familiar with either the design or what performance you expect of it, don't have a clue.
GM
I just want >100db sensitivity from say 30hz on up. If you'd like... I can buy you a set of the plans and you can look over them, a good opinion is worth $10 for sure!
Greets!
Not sure what constitutes a 'slim' baffle, but just looking at the single driver SPL plot for a 30" wide baffle it's ~93 dB/30 Hz/half space, so I doubt it would hit 100 dB unless corner loaded in a small, well sealed room. If the 'slim' model is smaller, then its sens. will be even less for a given BW.
Anyway, the folks who've built them would be your best source of 'hands on' info, so what do they say?
GM
Not sure what constitutes a 'slim' baffle, but just looking at the single driver SPL plot for a 30" wide baffle it's ~93 dB/30 Hz/half space, so I doubt it would hit 100 dB unless corner loaded in a small, well sealed room. If the 'slim' model is smaller, then its sens. will be even less for a given BW.
Anyway, the folks who've built them would be your best source of 'hands on' info, so what do they say?
GM
Graphs is not all that they appear to be
THe SPL measurements are taken outside. So on the low end you can expect close to 10 db gain due to corner and wall loading. So you probably will end up with more than you hoped for.
BassAwdyO I doubt that the driver you have is at 100db/watt at 30 hz in any othet box. If you get around 90 db/ watt you will with the gain that you have allready noted ( about 10 db ) get to your goal.
My personal preference is to go with a dual driver configuration. You get another 3db real world output. That's the same volume with half of the power going in!
MArk
THe SPL measurements are taken outside. So on the low end you can expect close to 10 db gain due to corner and wall loading. So you probably will end up with more than you hoped for.
BassAwdyO I doubt that the driver you have is at 100db/watt at 30 hz in any othet box. If you get around 90 db/ watt you will with the gain that you have allready noted ( about 10 db ) get to your goal.
My personal preference is to go with a dual driver configuration. You get another 3db real world output. That's the same volume with half of the power going in!
MArk
Nevermind...
I'll just bite the bullet on this one and build it...
10db efficiency increase will mean somewhere around 98db@1w, which isnt bad at all.
Look at the Tumult pricetag and say that again...
the "slim" version is 20 inches wide x36 x36
When I'm bored enough(have alot of time on my hands) I'll get the plans and ALOT of wood. And of course start another dedicated thread with pictures...
The autotuba driver has arrived. I'll say it's got a beefy motor for an 8" driver and judging in free air about 1"p-p linear excursion. Not too bad. It sould have more sewpt volume than the extremis and therefore go lower. Especially when I get that puppy in a car.
I think the autotuba is almost perfect for auto application. It's not too large, it's cheap, and it plays fairly loud(and probably low in a car). Not to mention it only requires 100watts which means that most standard auto electrical systems should have no problem pushing the amp for it.
I'll just bite the bullet on this one and build it...
10db efficiency increase will mean somewhere around 98db@1w, which isnt bad at all.
Look at the Tumult pricetag and say that again...
the "slim" version is 20 inches wide x36 x36
When I'm bored enough(have alot of time on my hands) I'll get the plans and ALOT of wood. And of course start another dedicated thread with pictures...
The autotuba driver has arrived. I'll say it's got a beefy motor for an 8" driver and judging in free air about 1"p-p linear excursion. Not too bad. It sould have more sewpt volume than the extremis and therefore go lower. Especially when I get that puppy in a car.
I think the autotuba is almost perfect for auto application. It's not too large, it's cheap, and it plays fairly loud(and probably low in a car). Not to mention it only requires 100watts which means that most standard auto electrical systems should have no problem pushing the amp for it.
When I get some time I'll take the enclosure apart, outfit the MCM and possibly do some measurements. Stay tuned...
BassAwdyO said:
boy, .. you're going to be surprised by what a mere 8" can do in a horn , ... never tried the autotuba in a car though, .. interested in opinions.
WHat do bullets taste like?
Given that the driver used in Bill's test box is about 95 db/watt he is getting that as a baseline. Your driver I think is about 88 db. Remember that the measurements are taken outside and that there will be room gain. You will get relatively close to the 100 db at 30 hz that you are after.
Definitely worth building and listening to! WIth your driver the maximum SPL will be about 9 db louder when you factor in the greater excursion capability.
My comment about the dual configuration was supposed to apply to conventional drivers. Two decent 15's will almost equal your over the top woofer. And be cheaper to boot!
Keep in mind that the box can be redesigned and modified to go deeper and still be supported by the horn's gain.
If this is your first time then go with the proven design. If you like the sound then get back on the horse and figure out something that will do what you want.
Cool 8" ! That will do some serious but kicking to all those kids! I'm building the same thing for my car. Modified to accept two pioneer woofers and extended to get down to a clean 30hz. I love horn response!
Mark
Given that the driver used in Bill's test box is about 95 db/watt he is getting that as a baseline. Your driver I think is about 88 db. Remember that the measurements are taken outside and that there will be room gain. You will get relatively close to the 100 db at 30 hz that you are after.
Definitely worth building and listening to! WIth your driver the maximum SPL will be about 9 db louder when you factor in the greater excursion capability.
My comment about the dual configuration was supposed to apply to conventional drivers. Two decent 15's will almost equal your over the top woofer. And be cheaper to boot!
Keep in mind that the box can be redesigned and modified to go deeper and still be supported by the horn's gain.
If this is your first time then go with the proven design. If you like the sound then get back on the horse and figure out something that will do what you want.
Cool 8" ! That will do some serious but kicking to all those kids! I'm building the same thing for my car. Modified to accept two pioneer woofers and extended to get down to a clean 30hz. I love horn response!
Mark
Forgot the chart!
A couple of basic understandings with this graph.
The driver has a basic efficiency of 95 db/watt. Yours does not. So lower the overall gain by about 6db. The horn supported region above 40hz will give your driver a 10db gain. Or around 98 db/watt.
OK check the roll off. The horn unloads around 40hz due to the size of the horn mouth. A good design choice as most pop music and indeed most music has little bass below that. THe cool thing is that the driver is still giving usefull output below that due to the length of the horn. Don't forget the room gain that will had and you still should be in the 90 to 95 db region in room loudness at 30hz. A corner placement will give even more reinforcement at the expense of a bass hump. Move the box around a while before you get comfortable with the sound.
Hope this helps!
MArk
A couple of basic understandings with this graph.
The driver has a basic efficiency of 95 db/watt. Yours does not. So lower the overall gain by about 6db. The horn supported region above 40hz will give your driver a 10db gain. Or around 98 db/watt.
OK check the roll off. The horn unloads around 40hz due to the size of the horn mouth. A good design choice as most pop music and indeed most music has little bass below that. THe cool thing is that the driver is still giving usefull output below that due to the length of the horn. Don't forget the room gain that will had and you still should be in the 90 to 95 db region in room loudness at 30hz. A corner placement will give even more reinforcement at the expense of a bass hump. Move the box around a while before you get comfortable with the sound.
Hope this helps!
MArk
Attachments
well.... it wont be a bad bullet I'm sure... metaphorically speaking, maybe like a 22cal or something... not a 45 hollow tip or anything. I'm sure I will be very impressed with tuba36 loaded tumult and it will surely have ALOT more efficiency than the driver in any other enclosure type.
I got tha autotuba up and running. Definately better with the MCM than it was with the Extremis. For a 30dollar driver, it sure can pump out some bass! I'm going out of town this evening and wont be back until next week, but I should have time to do a few measurements then.
I got tha autotuba up and running. Definately better with the MCM than it was with the Extremis. For a 30dollar driver, it sure can pump out some bass! I'm going out of town this evening and wont be back until next week, but I should have time to do a few measurements then.
paulspencer said:
i can't answer for BassAwdyO , but in my experience comparing my autotuba to my shiva in a variety of a variety of enclosures as a point of reference, ...
<previous enclosures>
shiva in 16 ft straight "el pipo" type transmission line , .. low bass, but uneven room modes eventually forced me to disassemble this design (wouldn't fit in any other room in the house)
shiva in sealed enclosure, not enough low bass for my tastes, might work in another room
</previous enclosures>
shiva in 130+ litre EBS enclosure tuned to 17Hz (current) quite good for a bass reflex enclosure, not boomy and can hit the real low lows when necessary.
autotuba, more efficient than the shiva, has more midbass punch and less "overhang" than the bass reflex. doesn't go as low as the shiva (i'd say usable response IMHO is low 30's) . bass has a visceral impact and can eat your average electronics store subwoofer for breakfast.
some detractors have complained about uneven frequency response but i haven't found this to be an issue in real life.
i have had success mating it to planars, horns, and normal speakers, .. but have seen issues with integration in other systems (see point below)
especially sensitive to placement, perhaps not the best for very small rooms near to the listener (i'm quite happy with it in an approx 10 x 14 room around 12 ft away from me)
IMO, best crossed over low, say below 60 - 80Hz, as this enclosure has a rising response , although i use mine crossed over at 100Hz and placed at a wall equidistant from my tiny HT speakers.
power is by my 105 WPC mcintosh mc2100 (one channel to my autotuba and the other to the shiva, depending on which one i want to listen to)
hope that helps
Well I just got back from vacation...
To answer paul's question...
I assume you mean the difference between the tuba loaded extremis and MCM. Well the MCM definately goes lower. I wouldnt guess that it has a whole lot to do with the T/s parameters, but more so sheer displacement. They sounded very similar when crossed over at with my reciever's sub output. I believe that crossover point is way too high for the Tuba, or not a high enough slope. There seemed to be some midbass ringing or something just aweful in the higher bass. I think a lower crossover or higher slope might tame that. The MCM didnt really seem to be too much more efficient, but I couldnt do any A-B comparisons so I'm pretty sure I'm just hallucinating that.
Doing an A-B comparison with my Tumult(6cubic feet now tuned to 16hz) the tumult and autotuba were about equally loud when the tumult had nearly 8x the power. The tumult made the tuba look like a joke below 40hz, and the tumult sounded much better on the high bass also(no ringing and very hard to localize). They sounded quite similar however in the middle of their BW. I havent done any extensive listening yet, but once I do, I'm sure I will notice more subtle differences.
To answer paul's question...
I assume you mean the difference between the tuba loaded extremis and MCM. Well the MCM definately goes lower. I wouldnt guess that it has a whole lot to do with the T/s parameters, but more so sheer displacement. They sounded very similar when crossed over at with my reciever's sub output. I believe that crossover point is way too high for the Tuba, or not a high enough slope. There seemed to be some midbass ringing or something just aweful in the higher bass. I think a lower crossover or higher slope might tame that. The MCM didnt really seem to be too much more efficient, but I couldnt do any A-B comparisons so I'm pretty sure I'm just hallucinating that.
Doing an A-B comparison with my Tumult(6cubic feet now tuned to 16hz) the tumult and autotuba were about equally loud when the tumult had nearly 8x the power. The tumult made the tuba look like a joke below 40hz, and the tumult sounded much better on the high bass also(no ringing and very hard to localize). They sounded quite similar however in the middle of their BW. I havent done any extensive listening yet, but once I do, I'm sure I will notice more subtle differences.
Hmmmm interesting to hear, yes that's what I meant.
I wonder if your Tuba could benefit from some eq on the top end, from something like Ultracurve. It might be a bit hard to compare otherwise ...
I wonder if your Tuba could benefit from some eq on the top end, from something like Ultracurve. It might be a bit hard to compare otherwise ...
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