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#1 · (Edited)
The number of Devastator versions and the number of documented Devastator builds is multiplying, it would be nice if some of this information were kept more neatly in one place. This thread is a work in progress. I will add new variants to this thread and also builds and link them below. :cool:

As always, in the pursuit of performance from the use of wood! Wood is still cheaper than amps and sub woofers.... Let's not forget the other part of the Devastator formula, simplicity! (remember we are dealing with a band pass here, they are more complicated). No diagonals, all panels are on right angles to simplify the building process.

Note: there are also some guides linked below in this post. If you have questions about how to assemble a Devastator, there is a lot of good information in the builds, do this and do not this. That is on top of the build guide. Basic assembly works its way from the top and front panels, towards the back and downwards. Top hatches, rear panel vents, high compression fronts and Stepped fronts have all be added as the Devastator has evolved. Items are listed for the most part in Chronological order. Several members have put a lot of time in documenting the build process. Please check out their build threads!

Want to design a Devastator all on your own? The Hornresp tutorial is posted below. If you have design questions feel free to post them in that thread! There are tools for helping design cabinets in Google Sheets posted in that thread too.

With the addition of the Stepped front Devastators, responses can be mostly flat natively. Knowing your room and what can fit in a space are going to be key factors for selection vs trying to leverage the response shape in spot the suites the box well.

Suggestions for box selection: Devastators have seen evolutionary progress as time has gone on. The biggest factor for selecting a Devastator is the space available. That is one of the main driving factors for the wide array of designs beyond achieving more performance from the use of building material. Room size is another big factor. (I grabbed this from Audioholics)

Room
Dimensional Volume
Small Room​
< 1,500 ft^3​
Medium Room​
1,500 ft^3 to 3,000 ft^3​
Large Room​
3,000 ft^3 to 5,000 ft^3​
Extreme Room​
> 5,000 ft^3​

Small room, you can probably get away with a couple Micro 15" Stepped V1s. Medium room, you will need a couple 18"s at least. Large room - 21"s. Extreme, how many Fat Boy V5s can your marriage take? Other factors, is the room open to other areas and is it an odd shape? That can mess with the equation especially if sub placement options are limited.

Why bass physics suck:

Below is the Fat Boy Version 5 with the native 22Hz tune in gray and I tweaked the vent area down so it is now tuned to 18Hz. As you can see from the graph output takes a huge 5db hit from the lower tuning. In room that 22Hz box will probably stick with all the other Index Devastators down to 17Hz or 18Hz. That is a bit room dependent, so your mileage may vary. Also, remember 6db is the equivalent of doubling your sub system, amps, boxes and sub woofers, 3db from cone area and box displacement and 3db from the input power doubling.

Rectangle Slope Font Plot Parallel



Now I am going to push this further down to 15Hz tuning on the rear chamber. As you can see we are down a solid 10db on the left corner from the original 22Hz tuning and another 5db from the 18Hz tuning.

Rectangle Slope Font Plot Parallel


The important thing to know? Each octave (dividing a given frequency by 2) you descend in frequency will require 4 times the displacement to achieve a given level of output. Let's say when tuned 20Hz a box can hit 88db on 1 watt of power with 1mm of excursion. If we tune the box to 10Hz it would take 4mm of excursion from the woofer to hit 88db. This is an important fact when selecting a Devastator. There are three factors that will come into play. Output, Extension and Cost, those factors will always have to be balanced. You can chose 2, but you cannot get all 3 unless you are in a very small space that gains very well. A 7000 cubic foot room on a concrete slab is not a good place to chase extension. It would be better to go with higher tuned cabinets and gain the wobble effect from a BOSS platform. Unless you have the luxury of unlimited budget.

High Pass Filter Orders:

Real quick rundown, 6db of slope is an order. For example a 2nd order Butterworth filter will knock the response down 12db per octave. If set to 20Hz the response will be down 12db at 10Hz, assuming it is applied to a flat line. 2nd order filters can make integration easier in certain circumstances. Especially if the cabinet tunes have a wider range than just a few Hertz. Integration with sealed cabinets can be more tiresome and require a lot of trial and error. An 8th order 48db per octave slope on the sealed cabinet and then using a 2nd order HPF a few Hertz over tune on the Devastator can be a good starting point. Once again YMMV. If you do plan on using a 2nd order filter, go a little over tune with the filter to control driver excursion below tune.

Order: (typically you will not see a Dev go over a 4th order, just keep multiplying by 6 to go up)
1st 6db per octave
2nd 12 db per octave
3rd 18db per octave
4th 24db per octave

Why do we need High Pass Filters on a Devastator?

Below the tuning frequency of the Low Frequency(LF) resonator cone excursion goes out of control(see example below). The cone is no longer seeing a load like it would above the tuning frequency of the LF resonator. The cone movement would be similar to the sub being given power in free air. A pro driver can take several hundred watts in most cases in free air when sent a low frequency waveform. Doing that to a woofer frequently could A. damage the woofer over time and B. if sent a more powerful signal could bottom the woofer out immediately. The High Frequency (HF) resonator does present some load to the woofer below the LF tuning frequency, but it is not enough to control the cone movement. DO NOT RUN your Devastator without a protective high pass filter.

Rectangle Slope Plot Line Font


As you see in the graph above, the cone motion with the 2000 watt input on this NSW6021-6 has the driver well outside of the 21mm xmax below 20Hz. Once a Butterworth 18Hz 4th order high pass filter is actived the cone is peaking around 19mm below 20Hz(light gray line) and that is inside the NSW6021-6's rated xmax.

Slang/Terms:

HCR - High Compression Ratio. This front has a bell curve, but is not quite as peaky as a lower compression front and uses less space. Good for shallow cabinets.
TR - Tactile Response
Stepped - A front quarter wave resonator with 2 or 2+ cross sectional areas. The response is typically more flat and they gain more low end output.
BR - Bass Reflex
QW - Quarter Wave resonator. These are typically referred to as horns. On a Devastator they do the high frequency lifting.
FPR - First Port Resonance
BB - Baltic Birch plywood. (not the veneer box store stuff, call a lumberyard)
BBv1 - Big Boy Version 1
MLP - Main listening position.
REW - Room EQ Wizard.
HPF - High Pass Filter.
BW - Butterworth.
LF - Low Frequency
HF - High Frequency
HO/SHO - High Output or Stepped High Output. Usually these cabinets have 22Hz tuning.
BMD - Beast Mode Devastator. Typically they are closer to 60" height vs 48"
FV - Finalizer. This cabinet started as a 48"x25.5"x34" cabinet with lower tuning. FV can be used for the 16Hz tuned rear chamber or the form factor
Dev - Devastator. Generally cabinets that are around 48" in height.
Mini - Typically this cabinet type is around 40" in height.
Micro - Usually in the above or around 30" in height.
Nano - Usually used for 12" cabinets.
FB - Fat Boy. Typically as deep as they are wide.
BAMF - Bass Ascension Module Five. Home music or PA cabinet with higher tuning and a Stepped QW resonator.
NSW - Eminence NSW6021-6
SAN - Lavoce SAN214.50 or the SAN215.30 is another good choice, but not usually that is referring to the 214.50.
DS - That could be a B&C 21DS115 or a 18DS100-4, both are great choices.
TBW - B&C 18TBW100 is usually the reference, but the 15TBW100 is another good woofer.
SAF - Lavoce SAF184.03
WAF - Should be the Lavoce WAF154.00
D21V6 - This would be an example the Devastator 21" version 6
M18V6 - This would be an example of the Mini Devastator 21" version 6
FB21V5 or FBv5 - Fat Boy Version 5
FV1 - Finalizer Version 1

Devastator response evolution:

The Devastator has seen developments over time. The examples below are on 48" tall cabinets to show the three main fronts and how they affect the response.

The Devastator 21" Version 1 is the first Devastator designed by John. As you can see the front HF QW resonator adds SPL across the entire frequency range, peaking in the mid bass region. Light gray is ported cabinet with the same vent length, vent area and chamber volume as the D21V1.

Rectangle Slope Font Plot Parallel


Next up we have the Devastator 21" Version 5 with an HCR front. The HCR front has a smaller cross section area vs the lower compression front, but still adds output across the range and takes up less space in the cabinet. Once again dark gray is the V5 and light is just a basic BR chamber with the same specs.

Rectangle Slope Plot Line Font


Finally we have the Fat Boy Version 5 with its Stepped QW resonator that has multiple cross sectional areas. The higher tuning coupled with the design of the QW resonator makes the cabinet very flat and efficient. The higher tuning also allows the resonators to be spaced 1 octave apart in frequency without cutting our top end short, so this design can still crossover at 80Hz into a sound system.

Rectangle Slope Font Plot Line


Other advantages to having the front QW resonator:

Cone protection from curious children, pets and sometimes friends that are tipsy. Less rear chabmer/motor noise, the panels dampen noise that would otherwise find its way through the cone and into the room. Obviously the QW resonator eats up more space vs having nothing in front of the woofer, but the QW resonator has a few things going for it.

Construction/material/tips:

The preferred building material is currently expensive. Baltic Birch plywood (not the veneer stuff at box store, call a local lumber yard) is the preferred building material. 18mm is close enough to 3/4" not to mess up the building process. MDF is heavy and makes a big dust mess and does not take screws well, tends to crack. ACX plywood is lightweight, but has voids and a tendency to warp. BB is lighter than MDF and does not make the dust mess and is less prone to warping and also voids. MDF also sucks for using Kregs.

If you have router with a flush trim bit, it is not a bad idea to add 1/8" inch on the side panels and then clean it up after assembly.

PL3X is the glue of choice due to how forgiving it is with voids and set time. When using PL, wear gloves, you do not want that stuff getting on your skin and it will mess up clothing. If you are a fluent wood worker, you do not have to say no to tight bond.

Marking panels before assembly is another pro tip. I would also suggest marking up the woofer cutout and drilling all the holes for fastening the woofer before assembly. Marking the panel alignments/positions on the side panel, front panel and baffle are all good ideas. Measure twice, cut once is another good rule to live by.

Air leaks around the access panel are usually the number one issue once the box is together. Especially if the measured response looks weak on the left corner. If you want to make sure you have a good seal, turn off the lights, put a flashlight in the rear chamber. Button the hatch up and look for light coming through the hatch seal. Weather stripping or the PE gasket tape will work.

If you have a question or are unsure of something when putting the cabinet together, feel free to post the question in the Index. This thread has large following that is happy to offer tips!

Bracing - here is a good example of a common bracing mistake. The wider dimension should be adjacent to the outside panel, like in the photo below.

Driver mounting - Chris made this write up for his technique for securing the sub to the baffle - link



Threaded Inserts (Sub woofer mounting solution)

Panel Names?


Below is a reference image
Rectangle Parallel Font Plan Diagram


Rear Chamber Resonance/dampening material

Chris when testing the JBL Quad Devastator did some measurements with different pillow configurations in the rear chamber. We also reached out to a few members for measurements they took. It would appear standing waves in the rear chamber start to encroach on the passband somewhere between 40" and 48" of rear chamber length. Boxes close to 48" on up need pillows tacked onto the side panels to alleviate near past band resonance. The goal is having a clear path from the back of the woofer to the vent inlet. Air restriction will hurt low end output. However, if there is minimal restriction in air movement, a minimal loss in low end output will take place. Here are the links to the Quad testing.

Resonance Testing Pt1
Resonance Testing Pt2

Does my UM18/IB/high Qts Sub work in a Devastator?

The short answer is no, it does not work in a Devastator. This is a UM18 in a Mini Devastator 18 Version 6.



As you can see the woofer gets a very sharp peak at the resonant point of the front horn of the cabinet. You might be thinking why not just EQ that peak? Here is the problem, the UM18 will ring when loaded in a Devastator, the cone stays in motion after a impulse. This is the UM18 vs the 18TBW100, pink is the UM18, green is the TBW. Notice how the cone on the TBW stops moving relatively quickly. Some subs are designed to work well in higher order band pass boxes, others are designed to work in lower order band pass boxes. There is a simple method for finding a good woofer using a specific metric. Efficiency Bandwidth Product (EBP), the woofers Fs value divided by its Qes value. The Devastator starts working once a value gets around 70 or so. Values closer to 100 are better, but not absolutely necessary. If you have a woofer with a value higher than 70 and are curios to see how it looks, just post a message in the thread :)



Any Devastators optimized for music?

Yes, the BAMFs are designed to handle music duty/PA use. There are currently three different versions available with different tuning depending on the needs of your system. If interested I have a smaller design meant for an 18" that will definitely make some loud noise that has not been released yet.

I bought a Crown amp that has a network card, how do I manage it???
Chris made a nice write up concerning this situation, you can find it right here. You will need the Harmon Audio Architect software installed on computer that is on the same network as the USP card.

Reference Port Plug Design - link

Performance data (HR Estimations GP1m):
The Big Boy Family 21"s
The Fat Boy Family 21"s
The Finalizer Family 21"s
The Alpha Family 21"s
The BAMF Family 18"s + 21"s
The BMD Family 21"s
The Mini Devastator Family 21"s
The Devastator Family 21"s
The Mini Devastator Family 18"s
The Devastator Family 18"s
The BMD Family 18"s
The Micro Devastator Family 18"s

Shallow + Narrow 21" + 18" Devastators

Common 21 Comparison Graphic (shoutout to Chris for his help with this)
Rectangle Slope Plot Font Line


Common 18" Comparison Graphic
Rectangle Slope Plot Line Font


Current (9-1-22) top picks!
Colorfulness Slope Purple Rectangle Font

Note: The Alpha III and IV have narrow clones. The FBv6 has a narrower clone and the 18BMDSV2 has a clone.

PLEASE SHARE BUILDS IN THIS THREAD!!! (including pictures)

Designs (Guide is near the bottom of this post and see build links, a lot of go information in there.)

Broken down by woofer size:

24"
21"
18"
15"
12"
Build threads/other
Guides
 

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18
#3,732 ·
Rectangle Font Parallel Slope Diagram


This could work. Easier to get in and install the woofer. Also has dual function.
 
#3,733 ·
And you illustrated that you can indeed fit the SO into the cabinet!
Thank you.
:p
 
#3,737 ·
🤣😂🤣😂
 
#3,741 ·
Devastator = parallel tuned 6th order bandpass enclosure.
 
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#3,742 · (Edited)
I am changing up the Big Boys. The version 1 will be a 19Hz tuned cabinet and the version 2 will be a 16Hz tuned enclosure.

Here is a current Max SPL estimate for the current 16Hz tuned cabinet using 91 volts and 27mm. 91 volts is a little under 2200 watts.

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Comparison to 19Hz version

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After further analysis it looks like integration might be more tricky with the Big Boys when paring with direct radiators or Devs with shorter HF resonators. The phase shift has moved down in the response, I am comparing it to the FBv5 in the graphs for reference. The impedance swings are also more at the heart of the response vs other designs. I would recommended quality/robust amp for driving one of these, probably not the best for an iNuke.

Rectangle Slope Font Plot Parallel


Rectangle Slope Plot Font Parallel


Rectangle Slope Font Parallel Pattern
 
#3,744 ·
Props to RedFive, u kill n it!
 
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#3,745 ·
@Red Five , do you know if the vortex speaker would work in the devastator cabinet? Its the Dayton Audio PSS545HE-4 Vortex 21.

Another question, how well would the devastator cabinets integrate with an IB setup I have in the ceiling? The IB is 4-Fi audio 18's in ceiling, 3 ft from the rear wall (inny baffle?). I also have 4- um18-22's in sealed enclosures around the room. 1 to each side of MLP at the wall and 2 centered in the front under the screen. I'm going to change all these sealed enclosures to the marty's eventually to see if this helps to add bass as well.

That is current room setup. Right now i'm tossing around the idea of building 4 of the BMD stepped V1 and put them on either side of the screen stacked as pairs. lower one with ports on top and upper one with ports on bottom. I chose this box configuration because they are sized the right width for me (25.5") to fit on each side of the 117" wide screen and they will be stackable within my ceiling height (9'10").

The room- right now is open concept to the rest of the house through an opening or archway at the rear of the right wall of the room. 40" wide and about 9 ft tall. This will soon be closed off as there is a door to the back left of the room to the adjacent hallway. other than that it is a square room, 15x18.5, and has a concrete floor. obviously carpeted, lol.

The bass sounds really good right now just not loud for me and doesnt have TR. (I do own a pair of buttkicker LFE-bigger ones) I have looked at the BOSS setup, but im trying to avoid going that route again. pretty sure its the floor and rear opening that create losses against me in this new house, lol. I do use REW and have a mic to do the tuning.

Please share your thoughts. I love all the great info you guys share!

Ken
 
#3,746 ·
@Red Five , do you know if the vortex speaker would work in the devastator cabinet? Its the Dayton Audio PSS545HE-4 Vortex 21.

Another question, how well would the devastator cabinets integrate with an IB setup I have in the ceiling? The IB is 4-Fi audio 18's in ceiling, 3 ft from the rear wall (inny baffle?). I also have 4- um18-22's in sealed enclosures around the room. 1 to each side of MLP at the wall and 2 centered in the front under the screen. I'm going to change all these sealed enclosures to the marty's eventually to see if this helps to add bass as well.

That is current room setup. Right now i'm tossing around the idea of building 4 of the BMD stepped V1 and put them on either side of the screen stacked as pairs. lower one with ports on top and upper one with ports on bottom. I chose this box configuration because they are sized the right width for me (25.5") to fit on each side of the 117" wide screen and they will be stackable within my ceiling height (9'10").

The room- right now is open concept to the rest of the house through an opening or archway at the rear of the right wall of the room. 40" wide and about 9 ft tall. This will soon be closed off as there is a door to the back left of the room to the adjacent hallway. other than that it is a square room, 15x18.5, and has a concrete floor. obviously carpeted, lol.

The bass sounds really good right now just not loud for me and doesnt have TR. (I do own a pair of buttkicker LFE-bigger ones) I have looked at the BOSS setup, but im trying to avoid going that route again. pretty sure its the floor and rear opening that create losses against me in this new house, lol. I do use REW and have a mic to do the tuning.

Please share your thoughts. I love all the great info you guys share!

Ken
Ken,

I would not recommend that woofer for a Devastator. Inductance is going to cause issues in the response and also going to add distortion. A SAN or DS would be a much better option.

IB and sealed do not have a phase shift like a bass reflux enclosure. You can get IB and sealed to play with ported, but it might be something work with filter slopes and frequencies. You use a HPF to create a phase shift on the sealed/IB sub so it will sum with a BR cab. Otherwise you get cancellation around tuning frequency.

HOs will get the impact. DRs are not the best for moving particles that create the vibration. HOs are moving air in a good chunk of the response. The HF resonator for most of the HOs are hitting between 40-50Hz where things hit you hard in the torso.
 
#3,751 · (Edited)
Red Five: Can the NSW 21" in the devastator box on GSG's website actually compete with an Stereo Integrity HST 18" in 7ft3 tuned at 19hz? Not lower than 19hz but at 19hz. I would think the 18" would win with its extra xmax and being the much heavier of the 2. The 18" is 90 pounds and the NSW 21" is like 62 pounds I think?
 
#3,752 ·
I definitely want to try a devastator in the future. But I need a flatpack is why I want GSG's version of the dev. Will the NSW 21" dig to 19hz with authority or will it lose quite a bit of SPL down at 19hz? Also juat checked on parts express and the NSW 21" says it only plays down to 25hz at "product specifications" here:

 
#3,753 ·
This entire thread is a goldmine. You can look at the first page and see all of the different Dev`s and their tuning. You can roughly choose between 16-36Hz tuning with the DIY models. If you want the flat packs, it looks like 19 or 28Hz is your option. The graphs provided will convey more/better information than I can type.
 
#3,754 ·
Eventually I am going to catch up.... I am working on the Big Boy Version 3. 60x27x32, so a bit smaller, but still got some output. Tune is expected to be between 19Hz and 20Hz. NSW chugging on 1000 watts.

Rectangle Slope Font Parallel Plot
 
#3,756 ·
Font Rectangle Parallel Slope Screenshot


Are you talking long term output? CEA-2010 the X21 is almost at 119db. A GSG with an NSW will clobber that.
 
#3,759 ·
They are claiming 122db with the NSW.

 
#3,760 ·
They are claiming 122db with the NSW.


I believe you need to add 10db boost to the low end ?
 
#3,765 ·
If I run maximum SPL at 123 volts, so about 4000 watts with a 27mm excursion limit the Devs look like this. The MKI is very close to the D21V1, the MKII has a larger vent, not sure what velocity looks like on that. Anyways, vent velocity on the FBv5 will be a lot better.

Rectangle Slope Font Line Plot


Rectangle Slope Font Line Plot
 
#3,769 ·
@JasonGSG

Is an HO Devastator flatpack a pipedream from GSG? Right now when someone asks I can tell them there are two options of flatpack Devastators, the 19Hz tuned and the 28Hz tuned models from GSG. If you want an HO, your best bet is calling a buddy with a wood shop and bringing a case of beer with you. Not everyone is lucky enough to have a buddy with a wood shop.
 
#3,771 ·
@JasonGSG

Is an HO Devastator flatpack a pipedream from GSG? Right now when someone asks I can tell them there are two options of flatpack Devastators, the 19Hz tuned and the 28Hz tuned models from GSG. If you want an HO, your best bet is calling a buddy with a wood shop and bringing a case of beer with you. Not everyone is lucky enough to have a buddy with a wood shop.
I think having a selection of several different options for Devastator flatpacks would be awesome. It`s nice that you wouldn't have to keep more stock on hand since it`s all cut by CNC. All the types would come from the same stack of plywood.
 
#3,772 ·
There is so much overlap, as has already been noted in this thread, between many of the designs. I would love to see a better breakdown to the best 5 models (or 7 ;) ) for general usage...
What can be done with a narrow or shallow build, the no-holds-barred builds, true MBMs, etc?

I gotta say, the Stepped models are stunning, and that is possibly the greatest innovation so far in this epic journey of Bass Destruction!

I think another cool thing would be paying for a CNC file so that somebody could go to a local shop and have the milling done. @JasonGSG or anybody else with that knowhow? :)
 
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#3,775 ·
I just want more output at 19hz than my current TC Sounds LMS-R Ultra 5400 18" is giving with a Crown XLS 2500.
One of the reasons I asked is because I think it's easy to get into the mentality that a certain frequency defines the best output. Years ago, I thought all the good stuff in home theater was around 20Hz, but later I found out a lot of the content I thought was around 20Hz, was actually in the 30-60Hz range. When it's common said that you should go as low as you can for home theater, I think it misleads into the thinking that all strong content in home theater is really low, which isn't necessarily true.
 
#3,774 ·
The form factors have a lot of overlap as far as frequency response goes. Generally everyone wants shallow, not much care is given to height and width can become an issue for some. The slow evolutionary process gives way to more versions. The top hatch helped with squeezing larger vents in the cabinets, along with the shallower HCR fronts. Then the Stepped fronts allowed for much longer HF resonator paths with a much smoother response. The longer path led into other possibilities, since octave spacing between LF and HF resonators was possible without killing bandwidth on the top end.

If someone really really wants extension, they should look into sealed subs or go with massive LLTs with 24"s. There is no path without a lot of resistance when the goal is high SPL and low extension.
 
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