A 32Hz tuned TH for a dub soundsystem

[waxx]

I don't know if you know that music scene, but in dub and rootsdub parties are organised with big stacks of boxes tuned very low (32Hz is the goal) and bassheavy. They use 4 scoop horns (backloaded horns) with 18" drivers for the sub in a 3 till 5 way config and almost everything is custom handbuild, often by the dj crew themselves (see picture for the stack of Dub Stuy (NYC) for an example). A single stack is mostly 12-16kW and medium throw, wich is perfect for parties from 100 to 5000ppl (if you put a few stacks in the space). But for a small bar or party space (50-100ppl) this is way to powerfull, big and annoying for the neighbours because ofthe medium throw of the subs.

I know a lot of people in that scene here in Belgium and with some of them we discussed to make a smaller stack for bar gigs. I think a tapped horn would be best for this, but i can't find a fit design for this (also because my hornresp skill are very minimal, i'm a winisd guy for designing). The size may not be too big (the size of a standard scoop would be perfect) so an otthorn is out of the question. And other designs that are smaller that i see are tuned to high (35 till 40Hz). Is this possible to make a TH of arround 100dB on 1w/1m tuned to 32Hz or lower, about 800-1500w of power and of the size of a standard scoop (65cm wide, 120cm high and 80cm deep). Are there existing designs that are free to use (or cheap) and fit this conditions? And this preferable with a driver (or drivers) of less than 500€ for each box.

I could easely make a vented box (with more power to get the same spl), but i would prefer a TH for this (and many dubheads with me) because of the low frequency respone and efficiency.

 

[Brian Steele]

My POC4 ("B1") design got pretty close to a 32 Hz Fb within the dimensions that you specified (its external dimensions were 32" x 22.5" x 40"), so it should be possible to come very close to, if not meet, your specifications. The B1 never made it into live use (the owner moved on to other projects) and it's in need of updating. However, if you're interested in what the layout looked like, see link below.

The Subwoofer DIY Page v1.1 - Projects : "Proof of Concept #4"

 

[Dave R]

The Anarchy Tapped horns go down to 25 or 27 Hz.
The Anarchy woofer is 7".
TH is 8.38" W x 20.25" D x 30" H. (size is relatively compact) Terminus is 7.38"W x 5.38"H.
Don't know what their efficiency is @ 1W/1m.
And there's lots of noise above the usable bandwidth.
Nowhere near your 800-1500W wishlist either.

 

[kipman725]

There is no 'throw' for subs apart from a few exceptions they are omi directional. Loudspeakers are described as long, short medium throw based on their directivity. The only solution to your small space sound leakage problems is to turn it down unfortunately.

Saying that people often listen with their eyes so if you turn up with a physically smaller system even with the same dancefloor SPL you may have an easier time

 

[waxx]

Sorry, but that is ********. The horn of a scoop or a folded horn does push the sub to further in the field than a tapped horn (depending on the hornmouth), and certainly than a ported or sealed woofer. It's not that you don't hear it off axis like a line array, but there is certainly a throw that makes the subbass go further than a sub with no hornloading even if subbas is omnidirectional. I know that from 25 years in the field as soundengineer, dj and promotor. That horn also works as waveguide wich concentrate the subbass in a cardiod throw.

And we already did the test with a scoop with a Fane Colossus 18XB driver, and the same driver in a ported cabinet in a small bar measuring the noise at the neighbours house. The neighbour (who lives in the line of fire of the scoop) had about 6dB more noise with the scoop than with the ported cabinet on the same level in the bar. That bar changed their 2 scoops they had as sub for ported cabinets with the same fane driver (but 2 drivers and double the amp power to make up for the loss of efficiency) and had much less noise complaints after that while keeping the same spl level inside.

 

[tonskulus]

Hog scoop, it has depth of 95cm.. too deep?
It does 30Hz (especially if two or more stacked). It's tuned lower than traditional scoop.

Bass horns has better directivity (or "throw") because of larger radiating area etc.. Room acoustics might be more problematic for horns tho..

 

[GM]

Is this possible to make a TH of arround 100dB on 1w/1m tuned to 32Hz or lower, about 800-1500w of power and of the size of a standard scoop (65cm wide, 120cm high and 80cm deep). Are there existing designs that are free to use (or cheap) and fit this conditions? And this preferable with a driver (or drivers) of less than 500€ for each box.

No clue ATM; what XO point/slope desired?

GM

 

[waxx]

No clue ATM; what XO point/slope desired?

GM

Traditionally around 85hz and 4th order L/W where the kickbins take over...

 

[wg_ski]

Horns (tapped, rear loaded, or front loaded) use Hoffman’s iron law in reverse. The reason they are more SPL per watt than a vented box with a given tuning is because they are larger. Make it smaller and you drop efficiency/sensitivity. If you have a specific box size in mind, the only way to get the SPL and directivity back is to use a larger array of them. Othorns are tuned low, but larger than your target and not quite 100dB/W either. If you continue to make horns smaller and smaller (while maintaining the same tuning frequency) you eventually get to a point where there is no output advantage over a regular vented box.

 

[Brian Steele]

32 Hz 100+dB TH using the B&C 18TBX100 (published specs). Box size is the "standard" scoop horn as previously mentioned. I doubled up on the thickness of the top and bottom panels and the driver baffle. Required bracing is not displayed in the image.

So yes, it's possible.

 

[GM]

Horns (tapped, rear loaded, or front loaded) use Hoffman’s iron law in reverse.

Yeah, the scoop's theoretically big enough for 5% @ 30 Hz = ~99 dB, but driver, etc., losses makes us lucky to get it at 32 Hz.

GM

 

[GM]

So yes, it's possible.

Oh, so it only has to be down to 32 Hz in a four square stack?

GM

 

[Brian Steele]

OP's question was "Is this possible to make a TH of around 100dB on 1w/1m tuned to 32Hz or lower?" This design appears to meet that specification. I'm not sure that it meets the power-handling though (I modeled it using the B&C 18TBX100)

 

[waxx]

Oh, so it only has to be down to 32 Hz in a four square stack?

GM

No, that is not what i ask. I want that response with one th.

 

[GM]

Hmm, OK, to clarify, my original understanding was you want 32 Hz/~100 dB, which requires a lower tuning, whereas Brian's sim is only ~96 dB/32 Hz, rising to 100+ dB, so has he given you what you want?

GM

 

[waxx]

Ok, it's very early in the morning here, my brain did not work yet. But it looks like that one is good. I'm going to study it more. Thanks for the response.

 

[Circlomanen]

A slightly enlarged ROAR18 with a B&C 18DS115-4 can produce 131 dB @ 32 Hz 2,0 Pi with 2200 watts of power.

It will have a very powerful tactile reproduction of bass and a great midbass impact and punch, perfect for dub and reggae.

A friend tested playing bass guitar on my ROAR12 and it was to powerful for his needs (up to 100 persons in small indoor venues). He really loved the sound, the attack and crisp high definition, but it was to physically overwhelming for his needs.

The size may not be too big (the size of a standard scoop would be perfect) so an otthorn is out of the question

I missed this part so my proposed ROAR18 is out of the question (it is huge!!)

Regards,
Johannes

 

[SillySounds]

Sorry, but that is ********. The horn of a scoop or a folded horn does push the sub to further in the field than a tapped horn (depending on the hornmouth), and certainly than a ported or sealed woofer. It's not that you don't hear it off axis like a line array, but there is certainly a throw that makes the subbass go further than a sub with no hornloading even if subbas is omnidirectional. I know that from 25 years in the field as soundengineer, dj and promotor. That horn also works as waveguide wich concentrate the subbass in a cardiod throw.

And we already did the test with a scoop with a Fane Colossus 18XB driver, and the same driver in a ported cabinet in a small bar measuring the noise at the neighbours house. The neighbour (who lives in the line of fire of the scoop) had about 6dB more noise with the scoop than with the ported cabinet on the same level in the bar. That bar changed their 2 scoops they had as sub for ported cabinets with the same fane driver (but 2 drivers and double the amp power to make up for the loss of efficiency) and had much less noise complaints after that while keeping the same spl level inside.

outdoors throw is only to do with how loud the cab is playing. what your explaining in your test is to do with room dynamics. to have a cardiod setup you need many subwoofers. sometimes refered to power alley/bass alley.


Btw maybe look at xoc1 th18. a lot of documention on a thread here, should be very good for what you need (if Danley thinks it works i think its a good sign

 

[Xoc1]

There is a lok of information in the Flat to 30 Thread
C/E/X PA Flat to 30 (FT30) PA TH Awesomeness,
This Plan is close to your requirements
C/E/X PA Flat to 30 (FT30) PA TH Awesomeness
End Result
C/E/X PA Flat to 30 (FT30) PA TH Awesomeness
Tapped horns tuned this low need large excursion to avoid that being the limitation of the design.

 

[kipman725]

Sorry, but that is ********. The horn of a scoop or a folded horn does push the sub to further in the field than a tapped horn (depending on the hornmouth), and certainly than a ported or sealed woofer. It's not that you don't hear it off axis like a line array, but there is certainly a throw that makes the subbass go further than a sub with no hornloading even if subbas is omnidirectional. I know that from 25 years in the field as soundengineer, dj and promotor. That horn also works as waveguide wich concentrate the subbass in a cardiod throw.

And we already did the test with a scoop with a Fane Colossus 18XB driver, and the same driver in a ported cabinet in a small bar measuring the noise at the neighbours house. The neighbour (who lives in the line of fire of the scoop) had about 6dB more noise with the scoop than with the ported cabinet on the same level in the bar. That bar changed their 2 scoops they had as sub for ported cabinets with the same fane driver (but 2 drivers and double the amp power to make up for the loss of efficiency) and had much less noise complaints after that while keeping the same spl level inside.

Here is some data:
Tapped Horn Directivity
Keep in mind though frontal area is the dominant factor.