Newbie -- curious about tuba vs direct radiating

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STIchris722
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Newbie -- curious about tuba vs direct radiating

#1 Post by STIchris722 » Tue Jul 03, 2018 5:42 pm

Hello all. Newbie here. I purchased plans for a tuba 24 I believe it was about a year ago and haven't gotten around to building it. For my first project I went a simplistic and built a 4 ft^3 enclosure tuned to 44Hz with an Eminence Kappalite 3015LF. I absolutely love the thing and the output is exactly as it should sound to me. The idea of a folded and or tapped horn really intrigues me, but I know nothing about them. I was hoping someone could explain with data or graphs something that would compare a sub like I described with that of a tuba. Also another question.....Isn't there something about not being able to hear when a tuba is being over driven due to the inherent design.

Of Bill's products, what do I need to make to give me the equivalent output of four (4) of these 15's I've already built? I apologize if this info is already available, but I searched and came up with nothing....and I'm new so cut me some slack!

Thank you,
Chris
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J_Dunavin
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Re: Newbie -- curious about tuba vs direct radiating

#2 Post by J_Dunavin » Tue Jul 03, 2018 6:46 pm

Welcome!

I can definitely attest about not hearing Distortion through Bill's designs. It is very important to follow the plans and make sure your limiters and crossovers are set properly.

PS nice work on your ported box there :D
8 - DR200
2 - DR250
9 - T24
6 - T45
1 - Auto Tuba

STIchris722
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Joined: Tue Jul 03, 2018 11:15 am

Re: Newbie -- curious about tuba vs direct radiating

#3 Post by STIchris722 » Tue Jul 03, 2018 6:53 pm

Thank you. I know it's not one (1) of the designs of this website, but I was proud as it was my first project. Out of curiosity, how are companies like Cerwin Vega making "folded horns" with 15, 18, and 21 inch speakers, but I read an article on here that says it's not possible. I am definitely not doubting it, but curious how they are doing it.

CoronaOperator
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Re: Newbie -- curious about tuba vs direct radiating

#4 Post by CoronaOperator » Tue Jul 03, 2018 7:57 pm

STIchris722 wrote:
Tue Jul 03, 2018 5:42 pm
For my first project I went a simplistic and built a 4 ft^3 enclosure tuned to 44Hz with an Eminence Kappalite 3015LF.
I modeled that in win ISD and it looks like you have a 1w/m efficiency of about 97 db/w-m (above 60 hz) and a -3db at around 50hz, -10 dB around 35hz (where your x-max also maxes out). Also a max spl of about 124 dB's at around 70hz.

4 T39's would best it. Since you already have the drivers, T48's would go a lot lower in frequency than those cabs of yours but of course are bigger boxes.

Horn's however are super clean compared to a direct radiator, once you get used to the clean bass, it's hard to listen to a direct radiator sub after that. All speakers create harmonics when they play a note, a folded horn filters out the majority of those due to the path length difference between the inside of the horn and the outside of the horn. Kind of like in track and field the runners have to stagger because the outside lanes are longer than the inside ones. That smears the timing just enough to allow the shorter wavelengths (higher frequencies) to cancel by lining up their peaks and troughs while leaving the lower frequencies alone.

Those cerwin vega's are not real horns. The path length of those boxes is only 4 or 5 feet. Since these horns need at least a 1/4 wavelength to get any appreciable gain, they only horn-load to about 60 or 70 hz.

I don't remember Bill saying it was impossible to use an 18" driver, just that he won't do it as you get better results with multiple 12's rather than an 18". The 18" and larger inch drivers tend to shred due to the high throat pressures and the larger cone area those drivers have. By design, you could lower the throat pressure for the bigger drivers but then you lose performance. Need more output? Build more cabinets.
Built:
17" width 10" driver Autotuba
2 x 29" width dual Lab12 Tuba60
6 x DR250 2510/asd1001
In progress:
2 x DR250 2510/asd1001
For best results, point the loud end of the array towards the audience

CoronaOperator
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Re: Newbie -- curious about tuba vs direct radiating

#5 Post by CoronaOperator » Tue Jul 03, 2018 8:08 pm

J_Dunavin wrote:
Tue Jul 03, 2018 6:46 pm

PS nice work on your ported box there :D
It is, while looking up the T/S specs of the 3015lf I noticed it is also showcased on partsexpress website: https://www.parts-express.com/eminence- ... r--290-598

:clap: :clap: :clap:
Built:
17" width 10" driver Autotuba
2 x 29" width dual Lab12 Tuba60
6 x DR250 2510/asd1001
In progress:
2 x DR250 2510/asd1001
For best results, point the loud end of the array towards the audience

STIchris722
Posts: 17
Joined: Tue Jul 03, 2018 11:15 am

Re: Newbie -- curious about tuba vs direct radiating

#6 Post by STIchris722 » Tue Jul 03, 2018 8:20 pm

CoronaOperator wrote:
Tue Jul 03, 2018 7:57 pm
STIchris722 wrote:
Tue Jul 03, 2018 5:42 pm
For my first project I went a simplistic and built a 4 ft^3 enclosure tuned to 44Hz with an Eminence Kappalite 3015LF.
I modeled that in win ISD and it looks like you have a 1w/m efficiency of about 97 db/w-m (above 60 hz) and a -3db at around 50hz, -10 dB around 35hz (where your x-max also maxes out). Also a max spl of about 124 dB's at around 70hz.

4 T39's would best it. Since you already have the drivers, T48's would go a lot lower in frequency than those cabs of yours but of course are bigger boxes.

Horn's however are super clean compared to a direct radiator, once you get used to the clean bass, it's hard to listen to a direct radiator sub after that. All speakers create harmonics when they play a note, a folded horn filters out the majority of those due to the path length difference between the inside of the horn and the outside of the horn. Kind of like in track and field the runners have to stagger because the outside lanes are longer than the inside ones. That smears the timing just enough to allow the shorter wavelengths (higher frequencies) to cancel by lining up their peaks and troughs while leaving the lower frequencies alone.

Those cerwin vega's are not real horns. The path length of those boxes is only 4 or 5 feet. Since these horns need at least a 1/4 wavelength to get any appreciable gain, they only horn-load to about 60 or 70 hz.

I don't remember Bill saying it was impossible to use an 18" driver, just that he won't do it as you get better results with multiple 12's rather than an 18". The 18" and larger inch drivers tend to shred due to the high throat pressures and the larger cone area those drivers have. By design, you could lower the throat pressure for the bigger drivers but then you lose performance. Need more output? Build more cabinets.
Sorry, that is what I meant....The shredding of the drivers due to throat pressures. That is where my confusion came in when I knew that Vega was making "horns" with large drivers. Your explanation clears that up though.

I am not dead set on using a 15 by any means. I love those kappalite 3015LF only because they have great sensitivity and xmax compared to anything else I have found. I wouldn't mind using some 10s, or 12s or whatever configuration makes sense. I thought I read somewhere that people were using those LAB12 drivers, but there were some drawbacks to them with the power handling and xmax capabilities. How would the Tuba 24 compare to my madmax creation? I only ask because I already have those plans.

Something else I questioned and don't get defensive please was the construction using 1/2" BB ply. As a cabinet makers son I am very familiar with wood working and without creating a CNC dato or trying to precision biscuit the pieces in place, 1/2" seems like it would be difficult to work with. My personal opinion (again don't hate) was that 5/8" might be easier to work with. I have a CNC coming from Baileigh industrial here soon so it really wouldn't be an issue, but I was curious of what others have ran into with the 1/2" construction. Are you all using interior or exterior grade Baltic Birch; yes there is a difference. I also prefer titebond 1 vs the 2 or 3 or even the PVA glues like Gorilla. Is that going to be an issue?

Anyone have any cabinet covering solutions out there that work better than duratex? That stuff you look at it wrong and it chips off....even with a high quality primer underneath with solid surface prep. I called my local LineX dealer and they were interested, but I can only imagine what that would cost with the UV inhibitor. Thoughts?

Regards,
Chris

STIchris722
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Re: Newbie -- curious about tuba vs direct radiating

#7 Post by STIchris722 » Tue Jul 03, 2018 8:26 pm

CoronaOperator wrote:
Tue Jul 03, 2018 8:08 pm
J_Dunavin wrote:
Tue Jul 03, 2018 6:46 pm

PS nice work on your ported box there :D
It is, while looking up the T/S specs of the 3015lf I noticed it is also showcased on partsexpress website: https://www.parts-express.com/eminence- ... r--290-598

:clap: :clap: :clap:
Yeah that would be my review. I was pretty proud of it, but am starting to think I can do something better. That's why I'm here.
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Re: Newbie -- curious about tuba vs direct radiating

#8 Post by J_Dunavin » Tue Jul 03, 2018 8:34 pm

Couple of things:
The 1/2 is plenty strong, especially since there are so many internal pieces acting as bracing, very solid design!
The only "problem" is that you would throw the measurements off. It could be done, but totally unnecessary, and extra weight.

Correct me, but I don't believe the titbond expands, PL number 3 can fill in some gaps and expands a little, which is good for some of my cuts :roll:
An airtight driver chamber is critical.
Last edited by J_Dunavin on Tue Jul 03, 2018 8:37 pm, edited 1 time in total.
8 - DR200
2 - DR250
9 - T24
6 - T45
1 - Auto Tuba

CoronaOperator
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Re: Newbie -- curious about tuba vs direct radiating

#9 Post by CoronaOperator » Tue Jul 03, 2018 8:37 pm

STIchris722 wrote:
Tue Jul 03, 2018 8:20 pm
I thought I read somewhere that people were using those LAB12 drivers, but there were some drawbacks to them with the power handling and xmax capabilities.
The LAB12 has great x-max and power handling, it's drawback is that it weighs 24 lbs :shock:
Built:
17" width 10" driver Autotuba
2 x 29" width dual Lab12 Tuba60
6 x DR250 2510/asd1001
In progress:
2 x DR250 2510/asd1001
For best results, point the loud end of the array towards the audience

commander_dan
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Re: Newbie -- curious about tuba vs direct radiating

#10 Post by commander_dan » Tue Jul 03, 2018 8:38 pm

The 1/2" ply is fine, no problems. If you want to use something different, you'll have to adjust the internal dimensions otherwise the horn path geometry will be off, and you'll lose performance... that's pretty complex... much easier to just use the recommended ply, and I've heard of no-one on here who has had any dramas. I've used both marine ply and lower grade radiata ply in separate builds. The radiata warped alot more once the sheets were cut, but the construction tips in the plans show you how to remove the warp as you install each panel.

I haven't had too much drama with duratex but I primed and used two thick coats, and I also take care moving my cabs... itd probably be a different story if they were clunking around in the back of a truck doing regular tours.

What's your thinking behind going with the T24? Size? You should work out what kind of content you want to replicate before choosing a design.
Built:
6 T30 (24", 3012LF)
2 OT12 (MA, 3012HO)
2 T24 (18", 3010LF)

Running:
DCX2496
XTi 2002
XTi 4002
TRAKTOR Z2
TECHNICS 1210 Mk5's

STIchris722
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Re: Newbie -- curious about tuba vs direct radiating

#11 Post by STIchris722 » Tue Jul 03, 2018 8:41 pm

J_Dunavin wrote:
Tue Jul 03, 2018 8:34 pm
Couple of things:
The 1/2 is plenty strong, especially since there are so many internal pieces acting as bracing, very solid design!
The only "problem" is that you would throw the measurements off. It could be done, but totally unnecessary, and extra weight.

Correct me, but I don't believe the titbond expands, PL number 3 can fill in some gaps and expands a little, which is good for some of my cuts :roll:
An airtight driver chamber is critical.
Fair enough. I guess I was talking more about the ease of assembly.

You are absolutely correct about the expansion. Titebond 1 definitely does not expand like the other brands of glues out there.

STIchris722
Posts: 17
Joined: Tue Jul 03, 2018 11:15 am

Re: Newbie -- curious about tuba vs direct radiating

#12 Post by STIchris722 » Tue Jul 03, 2018 8:44 pm

commander_dan wrote:
Tue Jul 03, 2018 8:38 pm
The 1/2" ply is fine, no problems. If you want to use something different, you'll have to adjust the internal dimensions otherwise the horn path geometry will be off, and you'll lose performance... that's pretty complex... much easier to just use the recommended ply, and I've heard of no-one on here who has had any dramas. I've used both marine ply and lower grade radiata ply in separate builds. The radiata warped alot more once the sheets were cut, but the construction tips in the plans show you how to remove the warp as you install each panel.

I haven't had too much drama with duratex but I primed and used two thick coats, and I also take care moving my cabs... itd probably be a different story if they were clunking around in the back of a truck doing regular tours.

What's your thinking behind going with the T24? Size? You should work out what kind of content you want to replicate before choosing a design.
Okay that was what I was looking for. Thank you for the response.

T24 was just the plan that I purchased at the time. I can use a different one for sure if that's what you all recommend. I was just sold on the portability and size. Nothing more.

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Re: Newbie -- curious about tuba vs direct radiating

#13 Post by J_Dunavin » Tue Jul 03, 2018 8:55 pm

I currently have four BP102 loaded T24s and I do love the size, but I don't think they would keep up with your current set up.
Now, 3010LF loaded ones might.
8 - DR200
2 - DR250
9 - T24
6 - T45
1 - Auto Tuba

STIchris722
Posts: 17
Joined: Tue Jul 03, 2018 11:15 am

Re: Newbie -- curious about tuba vs direct radiating

#14 Post by STIchris722 » Tue Jul 03, 2018 9:00 pm

J_Dunavin wrote:
Tue Jul 03, 2018 8:55 pm
I currently have four BP102 loaded T24s and I do love the size, but I don't think they would keep up with your current set up.
Now, 3010LF loaded ones might.
Is that with two (2) 3010LF's per enclosure or just one (1)? I thought I remembered reading where you could widen the enclosure and put two (2) drivers in it. I still have access to those Eminence drivers so that wouldn't be an issue

CoronaOperator
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Re: Newbie -- curious about tuba vs direct radiating

#15 Post by CoronaOperator » Tue Jul 03, 2018 9:08 pm

STIchris722 wrote:
Tue Jul 03, 2018 8:44 pm
T24 was just the plan that I purchased at the time. I can use a different one for sure if that's what you all recommend. I was just sold on the portability and size. Nothing more.
In order to give a recommendation we need to know what you plan on doing with the cabs. Indoors/outdoors? Live music/pre-recorded music? What kind of music? EDM has very different requirements frequency wise than bluegrass. What size crowds do you play? Your living room or a 400 person venue? How loud do you want to play? Dance club/rock concert volumes or family friendly volumes? Are you a mobile operator or is this a permanent location? How big is your car/truck to haul this stuff around? Do you have room to store larger/more cabs in between gigs?

They all sound good for their intended purpose. The larger the tuba's the lower they go in frequency, how low you need depends on the music genres you play. The titans are more geared towards live music so they go loud around the kick drum / bass guitar frequencies.

edit: Lastly, what are you trying to improve on? Volume? Sound quality? Lower frequency response? Punch? Also, what tops are you using ? Many perceived problems with the bass (like punch) are actually lower midbass problems with your top boxes and not the actual subs themselves.
Built:
17" width 10" driver Autotuba
2 x 29" width dual Lab12 Tuba60
6 x DR250 2510/asd1001
In progress:
2 x DR250 2510/asd1001
For best results, point the loud end of the array towards the audience

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