I want to build a subwoofer and the Devastator came up on a google search. I know nothing about audio and don't really want to get into the details. I have a great room that is 25' by 25' and vaulted 16' ceilings. I play a lot of pipe organ music that has a lot of bass. Would the Devastator be a good choice or would there be others that you could suggest?
To respond to your devastator question; a devastator is a fairly complicated 6th order bandpass box, which might be rough as a first project.
This video: 21 Inch DIY Subwoofer build guide! The best sub for your Home Theater. - YouTube
shows the work in just assembling a large 'flat pack' devastator build, where all the panels have been pre-cut by cnc.
>I know nothing about audio and don't really want to get into the details.
So... you don't actually want to diy anything at all? Just go buy one of these and be done with it; you don't have to get into any details: JTR Captivator 4000ULF — JTR Speakers.
More details: JTR Captivator 4000 ULF - The Sub of Power | AVS Forum
This video: 21 Inch DIY Subwoofer build guide! The best sub for your Home Theater. - YouTube
shows the work in just assembling a large 'flat pack' devastator build, where all the panels have been pre-cut by cnc.
>I know nothing about audio and don't really want to get into the details.
So... you don't actually want to diy anything at all? Just go buy one of these and be done with it; you don't have to get into any details: JTR Captivator 4000ULF — JTR Speakers.
More details: JTR Captivator 4000 ULF - The Sub of Power | AVS Forum
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Johnr9q
The Devastator Index | AVS Forum
There are dozens of "Devastators".
Generally they have in common huge size, high efficiency, and a rising upper bass response. The rising upper response is good if you want tons of "kick" or "punch", like being near subs at a dance club or rock concert (or car..) with SPL (sound pressure levels) of 125-140 dB.
Pipe organ low notes generally go down to 16 Hz, some go as low as 8 Hz though the fundamental tones are seldom as loud as the harmonics.
Even the largest real pipe organs very low frequency output seldom exceeds 100dB SPL.
In small rooms (an 8 Hz note is 141 feet long) the in room bass response can be very uneven, you would probably get a better result using 2-4 small sealed subs spread around rather than one single huge sub, which may end up in a bad position simply because of non-audio related considerations.
Art
The Devastator Index | AVS Forum
There are dozens of "Devastators".
Generally they have in common huge size, high efficiency, and a rising upper bass response. The rising upper response is good if you want tons of "kick" or "punch", like being near subs at a dance club or rock concert (or car..) with SPL (sound pressure levels) of 125-140 dB.
Pipe organ low notes generally go down to 16 Hz, some go as low as 8 Hz though the fundamental tones are seldom as loud as the harmonics.
Even the largest real pipe organs very low frequency output seldom exceeds 100dB SPL.
In small rooms (an 8 Hz note is 141 feet long) the in room bass response can be very uneven, you would probably get a better result using 2-4 small sealed subs spread around rather than one single huge sub, which may end up in a bad position simply because of non-audio related considerations.
Art
Attachments
thanks
Thanks Chompy and Weltersys, I am referring to the Devastator 21" by GSG. I have a lot of woodworking skills and thought a kit was just gluing a bunch of panels together. I wouldn't have any problem doing all the wiring and component integration like installing the speaker and amplifier because I am experienced in electronics, I'm just not knowledgeable in audio specifics. I would like the subwoofer to "rattle the windows" and make a sound that you can "feel". I currently have two Definitive Technologies 15" subs and they do a pretty good job however, one of them quit working so I wanted to replace it and still use the one I have left. What I am wanting information on is this, a good choice for my application and is the Devastator a good choice. When I look on the audio forums I see very little information on the Devastator making me think it isn't very popular. (if so, why)
Thanks Chompy and Weltersys, I am referring to the Devastator 21" by GSG. I have a lot of woodworking skills and thought a kit was just gluing a bunch of panels together. I wouldn't have any problem doing all the wiring and component integration like installing the speaker and amplifier because I am experienced in electronics, I'm just not knowledgeable in audio specifics. I would like the subwoofer to "rattle the windows" and make a sound that you can "feel". I currently have two Definitive Technologies 15" subs and they do a pretty good job however, one of them quit working so I wanted to replace it and still use the one I have left. What I am wanting information on is this, a good choice for my application and is the Devastator a good choice. When I look on the audio forums I see very little information on the Devastator making me think it isn't very popular. (if so, why)
I would take something that is more ment for hifi. The Dayton UM18-22 in a 300L sealed box can shake your house on 20Hz (F6) at 108dB (1000w) output on that frequency. It's also an easy build, the most dificult thing is probally bracing the box enough to handle that...
Some bigger tapped horns like the Otthorn do similar things but not that low. Just like the Devastator. Those are more ment for P.A. purpose and throw the sound further due to the horn (wich your neighbours won't like).
Some bigger tapped horns like the Otthorn do similar things but not that low. Just like the Devastator. Those are more ment for P.A. purpose and throw the sound further due to the horn (wich your neighbours won't like).
The frequency response chart I posted previously was for the different 21" Devastator options.
All those Devastator models have 10 dB or more rise between 20Hz and 100 Hz. If not equalized, that rise will make the upper range sound over twice as loud, or bass half as loud, compared to your Definitive Technologies 15" sub.
DSP (digital signal processing) is cheap, so equalizing different subs for optimum room response does not rule out mixing different types of subs.
Huge subs are not very popular simply because the size, weight and expense is not required for most users.
The position of the subs in the room can easily make more difference in the response at the listening position than the type of sub you use.
Since you are not knowledgeable in audio specifics, hard to say whether your present subs not being able to "rattle the windows" and make a sound that you can "feel" will be fixed by adding larger, louder subs.
Art
What I was hoping for, when I posted here, was some sort of consensus with people that are knowledgeable regarding audio. So far, it seems, I have found people that are knowledgeable regarding audio but no consensus. (except Waxx agreed with Troy at Dayton) I really want some of you to tell me your best opinion on what I am looking for, not a lot of technical information that I am not able to use. I probably should educate myself in the areas you are talking about but I just don't have the time or desire. I talked to Troy with Dayton, and he seemed knowledgeable and spent the time giving me advice. His suggestion was the Dayton Audio 18" Ultimax Subwoofer and Cabinet BundleBy. But I read on the Devastator website that this driver "has an efficiency in the upper bass of about 0.5% (one half of one percent), while the Devastator has an efficiency in the upper bass of 25%, which is 50 times greater!" So, it sounds like the Devastator is a better choice. Waxx also said "the Devastator is meant for P.A. purpose and throw the sound further. But then the Devastator people's response is "Originally designed as a high-output outdoor subwoofer, it turned out that with a port re-design it could work very well as a full range home-theater sub" Sorry to be so long winded. I f you need more answers to provide me a solution, just ask. (I don't mind the high cost of the Devastator)
If you are looking for consensus opinion, go with either camp, you will have plenty of support either way.
If you want to make a purchase based on other people's opinion, rather than using technical information to base your own informed decision upon, you might as well flip a coin, or average 20 responses from a Magic 8 Ball :^).
That said, if you don't mind the huge size, the very different sound of that "50 times greater" +10 dB upper bass response boost if not equalized, there is no reason to not go with a big bass reflex/horn hybrid.
So, if your binary choice goes to the Devastator, which of the dozen or more of the design options would you prefer?
Art
If you want to make a purchase based on other people's opinion, rather than using technical information to base your own informed decision upon, you might as well flip a coin, or average 20 responses from a Magic 8 Ball :^).
That said, if you don't mind the huge size, the very different sound of that "50 times greater" +10 dB upper bass response boost if not equalized, there is no reason to not go with a big bass reflex/horn hybrid.
So, if your binary choice goes to the Devastator, which of the dozen or more of the design options would you prefer?
Art
Art, actually I really appreciate your help. You said "So, if your binary choice goes to the Devastator, which of the dozen or more of the design options would you prefer?" I am not aware of a dozen options. I am looking at the Devastator MkII. Also, can you tell what you mean by "the very different sound of that 50 times greater"
John,
The GRS Devastators designs all have a large upper bass boost, or looked at it from the other side, reduced low bass compared to most subwoofers which are designed for "flat" response.
"Flat response" when shown on a frequency response graph is a straight ("flat") line, at each frequency from low to high the response is the same. Flat response is a good thing, "what goes in is what comes out".
To have flat response, the Devastator need the upper bass reduced by 6 to 12 dB. If the upper bass is not reduced (the efficiency thrown away) the resulting sound will be "thin", "weak", "anemic" or whatever non-technical term you want to use for upper bass that sounds 4 times too loud, or low bass that sounds 1/4 as loud as it was recorded.
In post #3 the curves on the graph are from various Devastators using the Eminence NSW6021-6 21-inch, one of the driver GRS suggests.
OK, so throw away (reduce) the upper bass efficiency seen on the chart to achieve flat response, or a LF "equal loudness contour" bass boost preferred by most when listening at lower than front row Deadmau5 levels, and all that "efficiency" makes little difference to the desired result.
Notes from the GRS Devastator II below, they suggest a +6 or +12 dB boost (gain) in the bottom.
For most DSP (digital signal processing), the inverse, cutting upper bass, rather boosting low bass would be preferable.
If you don't understand those notes, but are still interested in horn-loaded subwoofers, you have plenty of search terms to get you started!
Art
The GRS Devastators designs all have a large upper bass boost, or looked at it from the other side, reduced low bass compared to most subwoofers which are designed for "flat" response.
"Flat response" when shown on a frequency response graph is a straight ("flat") line, at each frequency from low to high the response is the same. Flat response is a good thing, "what goes in is what comes out".
To have flat response, the Devastator need the upper bass reduced by 6 to 12 dB. If the upper bass is not reduced (the efficiency thrown away) the resulting sound will be "thin", "weak", "anemic" or whatever non-technical term you want to use for upper bass that sounds 4 times too loud, or low bass that sounds 1/4 as loud as it was recorded.
In post #3 the curves on the graph are from various Devastators using the Eminence NSW6021-6 21-inch, one of the driver GRS suggests.
OK, so throw away (reduce) the upper bass efficiency seen on the chart to achieve flat response, or a LF "equal loudness contour" bass boost preferred by most when listening at lower than front row Deadmau5 levels, and all that "efficiency" makes little difference to the desired result.
Notes from the GRS Devastator II below, they suggest a +6 or +12 dB boost (gain) in the bottom.
For most DSP (digital signal processing), the inverse, cutting upper bass, rather boosting low bass would be preferable.
If you don't understand those notes, but are still interested in horn-loaded subwoofers, you have plenty of search terms to get you started!
Art
Attachments
Art, I'm sorry but I understand little of what you are talking about and would have a very confusing time researching it. Bottom line, it sounds like you think the best choice for me would be to get the Dayton UM18-22 in a 300L sealed box so that I can "rattle my windows and ability to feel the sound and get the neighbors knocking on the door". I don't just want that but also quality so it sounds like the Crystal Cathedral pipe organ. I figure if the bass is too overwhelming I can always turn it down?
I'm a big fan of organ music, esp the dramatic French literature, although the repertoire at Crystal Cathedral prolly not my cup of tea as much as St. John the Devine. You want a sub that goes real low and does so kind of effortlessly, if that's a physical correlate of that feeling.
How low the speaker goes is conditioned by how low the driver goes. Even at 10 cu feet (300 L) a sealed cabinet is raising the driver cut-off up rather too far. The only enclosures that let the driver alone are labyrinths and maybe that 300 L, filled with pillow stuffing and with the back left off.
For sure, you don't want a hokey complicated tuned box. You want untuned.
B.
How low the speaker goes is conditioned by how low the driver goes. Even at 10 cu feet (300 L) a sealed cabinet is raising the driver cut-off up rather too far. The only enclosures that let the driver alone are labyrinths and maybe that 300 L, filled with pillow stuffing and with the back left off.
For sure, you don't want a hokey complicated tuned box. You want untuned.
B.
It's not the only solution, but it's a way more logic one as the response is relative flat so it's easy to implement in your system. And the driver still can get very loud in a way more controlled way.
The Dayton is a high quality subwoofer driver that on it's own goes very low, and the box as a QTC (damping) near perfect (0.704, perfect is 0.707 and a 292L cabinet) and the response go to 20hz (F6). Sealed subs also give a way more accurate response as the group delay is smaller and the response is fully in phase. And it's a relative easy build. Just use enough bracing (a lot) and thick wood (preferable 21mm birch ply, if mdf use at least 24mm) as this driver pushes a lot of air arround...
You can look at the parts express cabinet for this driver. That is a good one for this driver, but too small to go as low as you wish (you loose 6hz), scale it up to 300L but use the same structure and you're good.
And i also listen to organ music, and have a sub that is tuned a bit higher, but sealed subs have a very slow rolloff so those lowest notes (16hz) are still there... This 300L cabinet will do that also.
The Dayton is a high quality subwoofer driver that on it's own goes very low, and the box as a QTC (damping) near perfect (0.704, perfect is 0.707 and a 292L cabinet) and the response go to 20hz (F6). Sealed subs also give a way more accurate response as the group delay is smaller and the response is fully in phase. And it's a relative easy build. Just use enough bracing (a lot) and thick wood (preferable 21mm birch ply, if mdf use at least 24mm) as this driver pushes a lot of air arround...
You can look at the parts express cabinet for this driver. That is a good one for this driver, but too small to go as low as you wish (you loose 6hz), scale it up to 300L but use the same structure and you're good.
And i also listen to organ music, and have a sub that is tuned a bit higher, but sealed subs have a very slow rolloff so those lowest notes (16hz) are still there... This 300L cabinet will do that also.
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Based on the information you all have provided, I will go with something like the Dayton UM18-22 in a 300L sealed box. Two questions:
1) waxx said "scale it up to 300L but use the same structure and you're good". Where would I get plans for the 300L? I can't find a 300L enclosure on the Parts Express site and if I'm going to "scale it up" I would need to build this myself.
2) Because I think bigger is better and I am going to scale things up anyway, instead of an 18" Driver, could I go with a 21" driver?
1) waxx said "scale it up to 300L but use the same structure and you're good". Where would I get plans for the 300L? I can't find a 300L enclosure on the Parts Express site and if I'm going to "scale it up" I would need to build this myself.
2) Because I think bigger is better and I am going to scale things up anyway, instead of an 18" Driver, could I go with a 21" driver?
Shape doesn't matter except to make a strong cabinet (avoiding large flat walls, having cross bracing). But have you figured how large is a box with an interior net volume of 300L (10.6 cu feet) has to be?
A 15-inch driver should move enough air cleanly and be a reasonable sweet-spot for cost and mechanical goodness. Basic criteria for me would be lowest driver resonance (Fo) and highest motor force (BL).
Of the drivers of interest, what are their resonances boxed in 300L and unboxed?
A single sub located according to acoustics and ugliness is likely. So a low crossover (like 100 Hz, maybe lower with an 18 or 21 inch driver) can't be exceeded and so you certainly will need an electronic crossover, one amp channel, and very wise to consider, digital signal processing (DSP) so as to fashion the sound curve.
B.
A 15-inch driver should move enough air cleanly and be a reasonable sweet-spot for cost and mechanical goodness. Basic criteria for me would be lowest driver resonance (Fo) and highest motor force (BL).
Of the drivers of interest, what are their resonances boxed in 300L and unboxed?
A single sub located according to acoustics and ugliness is likely. So a low crossover (like 100 Hz, maybe lower with an 18 or 21 inch driver) can't be exceeded and so you certainly will need an electronic crossover, one amp channel, and very wise to consider, digital signal processing (DSP) so as to fashion the sound curve.
B.
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The parts express cabinet is 4cuft (113L) and tuned higher, so you need to make a bigger variation of it if you want it. What i ment with scaling it up, is build a similar cabinet of 300L (10cuft) with a similar bracing scheme.
Dayton Audio 18" Ultimax Subwoofer and Cabinet Bundle
You could, but i don't see the use of it. Dayton has a driver that may be fit for it, the Dayton HTS545HE-4 Kraken, but i don't think it will be better than that UM18-22, only more expensive and bigger. It also needs a ported cabinet, not a sealed one. Other 21" are more ment to pro audio and don't go that low, only louder. So i would not do that. If one with the UM18-22 is not enough, i would build two of them (but i can't imagine that that will be the case).
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