# DIY Iso Cab Build Thread (Eminence, Sennheiser, World's Angriest Cat content)



## KhzDonut (Aug 31, 2013)

So I decided I was going to finally ditch POD HD as my primary recording solution, but since I prefer to not go deaf, I thought it would be a good idea to get an isolation cab instead of mic'ing a 4x12 or even a 1x12 in my fairly modest recording space.

The general consensus I've heard from people is that iso cabs can sound a bit "boxy" and pretty much all the YouTube demos I could find tend to justify this opinion. The only exception to this was the Rivera Silent Sister, which sounded really good. Even when using a similar/same speaker as another iso cab, it just sounded way better. Granted, this could be due to mic placement and any number of other factors, but the fact that it is "vented" seems to be the one real difference between it and other iso cabs, and it was the only one that sounded really, really good.

So I decided to do a design similar to the Rivera, with a snaking tunnel of vents running across the top and the ends.

Here is a highly sophisticated CAD blueprint:

(The arrows point where airflow will occur, snaking their way out of a padded labyrinth of chambers filled with sound-dampening foam.)









Here's the pieces of MDF cut to size (I failed to get the largest pieces in the shot, this isn't *quite* the entire lot. The cab will eventually measure 20" wide, 24" tall, and 40" wide. For the metric users, if my math is correct, that's about 51x61x102cm. For those using cubits, it's like a billion cubits. Totally)








Here's a picture of the foam I'm using on the inside. The big grey roll on the right is stuff I pulled out of an old adjustable mattress, and the stuff on the left represents about $8 worth of that stuff you put underneath your carpet to make it more padded. That stuff is like $0.25 per square foot, so I figured it would be a good choice to dampen the sound inside the snakey tunnels, and the larger textured foam would go inside the main chambers of the cabinet, where the speaker and mic are.








Speaking of mics and speakers! (Photobombing in the upper left you will see The World's Angriest Cat, and to the right you will see The Most Smug Feline In History. They're both rotten bastards, I assure you.)













The first pieces joined (blurry image, derp...)








The first bits of the sound-dampening air-venty snakey tunnel assembled. Shortly after this shot I ran out of glue, which I thought I had more of, but apparently that was a very incorrect assumption. Back to the hardware store!


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## Vostre Roy (Aug 31, 2013)

Looking sweet. I'll keep a close eye on this thread


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## vansinn (Aug 31, 2013)

Looks like it'll be a fine iso.

Couple of suggestions:
I'm not sure the foam will work too well. You might get better results using fluffy glasswool (the pink stuff) on the early part of the maze, and rigid glasswool towards the end.
I would suggest making arrangements for two additional phase-aligned mics, as this will allow capturing a 'bigger' sound. The chosen Sennheiser is nice, AFAIR with a tone sortof as a hybrid between the SM57 and 58.


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## Oneirokritikos (Aug 31, 2013)

Would this design be practical in an appartment setting, or would the dampened signal exiting the vent still be too loud?


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## KhzDonut (Aug 31, 2013)

Vostre Roy said:


> Looking sweet. I'll keep a close eye on this thread



Groovy. Love your signature, btw.



vansinn said:


> Looks like it'll be a fine iso.
> 
> Couple of suggestions:
> I'm not sure the foam will work too well. You might get better results using fluffy glasswool (the pink stuff) on the early part of the maze, and rigid glasswool towards the end.
> I would suggest making arrangements for two additional phase-aligned mics, as this will allow capturing a 'bigger' sound. The chosen Sennheiser is nice, AFAIR with a tone sortof as a hybrid between the SM57 and 58.



I'm going to make it so I have access to the venty tunnels when it's complete, so if it needs more dampening I can stuff some more material in there. I was a little uncomfortable handling the pink fiberglass insulation, so I thought I'd try this first. I'm a little skeptical myself, but I figured it was a cheap (albeit somewhat time consuming) first attempt.

Thanks for the advice on mics! I've got an SM58 laying around, so I figured I'd try that as well at some point. I'll have to grab a couple of goosenecks down the road.



Oneirokritikos said:


> Would this design be practical in an appartment setting, or would the dampened signal exiting the vent still be too loud?



Not sure yet, but I'll definitely post some clips of the sound from outside the cabinet when all is said and done. I'm in a condo, so that's definitely a concern for me. If all else fails I'll just plug up the vent with a lot more foam.


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## AwDeOh (Aug 31, 2013)

Can't wait to see how this sounds man.. I worked as a live soundie for a few years with the occasional studio gig for live clients as well, and I can think of a ton of times this would have come in handy.


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## Ulvhedin (Aug 31, 2013)

AwDeOh said:


> Can't wait to _see_ how this _sounds_ man..




But ontopic, I really hope this turns out good! Been meaning to build one for ages but the homemade ones I've heard sounds kinda 'meh'.


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## KhzDonut (Aug 31, 2013)

Progress so far today

The vent tunnels on the ends finished








The vent tunnels on the top finished and speaker baffle put in place








I had a lot of trouble padding all four walls of the vent tunnels and then joining everything together, so for the ones along the top of the cabinet I kind of cheated and just rolled some foam into a tube and stuffed it inside. For all I know it will actually work better, but it was definitely quicker and easier.








Halfway done padding the inside of the two main chambers. I used the lighter weight aggregate foam carpet padding behind the speaker, and the reclaimed textured foam for the chamber with the microphone.








I think the hardest thing about all this is that I made a dumb decision to just use wood glue for the foam. It does the job, but it takes a bit for it to dry, so I have to do one wall every 30 minutes or so, otherwise the foam will fall off if the surface it's on is upside down.

Next time: contact cement or aerosol adhesive. I hadn't wanted to use anything with a lot of harsh fumes or that was going to potentially get everywhere, but this is enough of a pain in the ass that I think it's a worthwhile trade-off.


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## Suitable (Aug 31, 2013)

Keen to hear how this turns out. What amp/amps are you going to be running through it?


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## Ghost40 (Aug 31, 2013)

> Here is a highly sophisticated CAD blueprint:



I lol'd at this. 

Great job so far man. I'm anxious to hear this thing. Most of the youtubes I have found reinforce the boxy sound as well.


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## KhzDonut (Aug 31, 2013)

Suitable said:


> What amp/amps are you going to be running through it?



Mesa Boogie Mini Rectifier


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## Lifestalker (Aug 31, 2013)

Ghost40 said:


> I lol'd at this.
> 
> Great job so far man. I'm anxious to hear this thing. Most of the youtubes I have found reinforce the boxy sound as well.



I was rolling too...haha.


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## KhzDonut (Sep 1, 2013)

So I got the Iso Cab finished (still working on clips, hopefully tonight or tomorrow)

My initial thoughts on how much it isolates sound is "not a lot" and I think that's largely due to a lack of foam padding in the main chamber. That's something I will remedy at some point, but right now I'll be content to just get used to recording with Mics and Speakers and Tube Amps (all POD X3/POD HD up until now!)

Here's some progress shots leading up to completion

Speaker baffle with foam cutout for speaker (overshot it a little on the foam cutting)








Speaker installed








Here's the "speaker access" panel, which is actually just the entire side panel of the Iso Cab, which allows access to the two main chambers, as well as the snakey vent tunnels.








Closeup of the open side of the Iso Cab. I used closed-cell vinyl foam weatherstripping as a seal along all surfaces, hopefully isolating each individual chamber to the fullest.








Closeup of the weatherstripping after the panel has been attached to the cabinet. This is after the first screw went in, it actually compressed quite a bit more once I cranked all the screws down.








The mic-access port. There's a little channel for the mic cable, and machine screws coming out of the cabinet itself for the port cover to attach to. I just used wing nuts to tighten it down.








And here it is completed, hooked up, sitting on top of some foam, and tucked away under the now mostly-defunct guitar-assembly portion of my office desk. (where you can see on of my current guitar projects sitting, waiting to be completed, cursing my name and crying out of neglect)


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## tssb (Sep 1, 2013)

First off, congrats on taking on this ambitious project 



KhzDonut said:


> My initial thoughts on how much it isolates sound is "not a lot" and I think that's largely due to a lack of foam padding in the main chamber.



More padding in there will help but I'm afraid that's not the main reason it isn't isolating very well. It's due to direct sound transmission through the MDF fins you installed between the inner box and the outer one.
Have a look at your first drawing, which was correct in drawing fins on either side of the cavity that don't make a join between the walls. The built one however makes a direct connection between the inner and outer walls, making all that padding in between rather pointless.

Then there's the issue of the large surface area of the walls that were not doubled. Those (sides and base) are only insulated with that one layer of foam.

To remedy some of this, I'd remove the fins, cut the depth of their profile down and make small rubber feet as supports for some of them, you want as few as possible connections between outer and inner layer). Also, i would stuff the sides and base with more padding, but keep this in mind : the more kinds of it the better. In simple terms, this is because every time sound has to travel through a different material, it loses some of its energy. So alternate between different padding materials, even if this means the layers are thinner.

Hope you find this useful, let me know if I can help in any other way.

Edit : that "speaker access panel" will be one of the first points the sound gets through, it's also the least insulated. Its entire surface needs to be covered, so there is no direct contact with the other pieces of MDF.


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## KhzDonut (Sep 8, 2013)

Hey thanks for the tips, tssb! And I agree, there's a lot of sound transmission going to the outer shell. One thing to note, the "speaker access panel" has the same amount of insulation as the other 2 single-ply walls, and it's connected to the main unit with foam weather stripping inbetween the two, so I don't think that's much worse off than the rest of it.

I've decided to build a second box with about an inch of padding on all sides, and a little bit of space between the inner box and the padding so that there's a layer of dead air between the first box and the outer layer. Hopefully that will also help to prevent vibration transmission between layers.

In addition to this I'm going to increase the amount of padding inside the original box, as well as make a secondary baffle to mount the speaker to. I'll put some padding between the main baffle and the secondary baffle, and hopefully that will reduce transmission of vibration from the speaker itself to the actual MDF structure.

I've got more MDF on the way and I've started cutting up all the foam padding. I've almost doubled the cost of the project, but hopefully it will all be worth it! (pics coming soon)


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## KhzDonut (Sep 12, 2013)

So my final conclusion was that the iso cab just wasn't "iso" enough. Even on "1" I could hear the guitar fairly well, and at "2" it was enough to annoy the neighbors, I'm sure. At "3" it would have been too loud to really use for recording, and would have *seriously* pissed off the neighbors. The joys of apartment living.

Anyway... I decided to first increase the amount of foam inside the initial build. The main/mic chamber got some extra under-carpet foam, and the secondary/speaker-back chamber got some of the egg-crate foam treatment.








And here's the pieces for the new, outer shell, as well as the secondary baffles (I made two so I could A/B speakers more easily in the future.)








Prepping the MDF sheets and foam for assembly.








Second shell coming together. You can't see it because the picture is so crappy, but I decided to use brackets to join everything together, and use weather stripping to pad the pieces at the joints. This increases the flexibility of the entire structure, and allows things to shift slightly. The reason for this is two-fold: a) I want it to be a little flexible because as much as I believe I do a decent job of measuring and assembling, I am not exactly cnc-machine precise. heheh. and b) the less direct, hard contact all the pieces have the less efficiently vibration transfers through the structure, so hopefully, a quieter structure. This is conjecture, of course, because I don't have any actual data to support that hypothesis, but it sounds good in my head. 








The second shell (incomplete) meets the modified original cabinet...








They move in close...








Looks like we have a love connection!








That's as fas as I got last night. I've gotten it almost complete today, but I'll post that tomorrow. It's getting late and I'm dead tired from all of this. This was WAY more work than I had anticipated.


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## RickyCigs (Sep 13, 2013)

this is looking good. a friend of mine built a smaller one that im sure he used a lot less padding. he never told me how well it worked, so im going to assume not very well.

can i ask why you chose mdf rather than birch plywood? im assuming its for its natural tone sucking abilities?


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## KhzDonut (Sep 13, 2013)

RickyCigs said:


> can i ask why you chose mdf rather than birch plywood? im assuming its for its natural tone sucking abilities?



That was actually part of it, I assumed it wouldn't transfer sound as well, but I don't really know for sure. It was also slightly cheaper, and I was a little unsure of how well the project would go. Also, MDF is really consistent and easy to work with, and I knew there would be no surprises with it.


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## RickyCigs (Sep 13, 2013)

KhzDonut said:


> That was actually part of it, I assumed it wouldn't transfer sound as well, but I don't really know for sure. It was also slightly cheaper, and I was a little unsure of how well the project would go. Also, MDF is really consistent and easy to work with, and I knew there would be no surprises with it.



That makes sense. Mdf sawdust is a BITCH though lol. It's so super fine and smells weird.


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## Deegatron (Sep 13, 2013)

I would like to see more "worlds angriest cat" content in this thread... perhaps some photoshop photo's of your cat attacking tokyo would be appropriate....
I hate to say it but he looks "grumpy" at best.....


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## KhzDonut (Sep 15, 2013)

Here are the final photos of "Iso Cab Mk. II"

It is finally complete!

Here's the original speaker input jack hole, which I had to plug up.









And here it is plugged. This is something I had to do a number of times for different holes and access points on the original cabinet. Derp. Luckily the hardware store had some dowel of *almost* the perfect size. Slight sanding took place, and a lot of smacking with a hammer. Was fun. (mild sarcasm)








Here's the "secondary baffle" which will hold the speaker. It'll make sense in a second.








Speaker loaded into the secondary baffle.








And here it is bolted in place. The idea here is that there is foam between the original baffle, and the secondary baffle, and there's neoprene washers between the metal washers and the contact points of the secondary baffle. It probably isn't actually helping a whole lot, but the idea was that it would help to reduce the amount of vibration transferring from the speaker itself to the actual shell of the cabinet. I didn't do an A/B test, so I can't say for sure how much of a difference it made, if any. I had much bigger fish to fry, and decided to just do it, and even if it didn't dampen sound, it would allow for an easy installation/removal of the speaker. I made two of these baffles, so if I want to A/B speakers that will be super easy.








Here you can see the mic pointed at the speaker, and you can see the layer of foam between the original baffle and secondary baffle.








Here's the speaker input wires going through the wall of the original cabinet, and snaking through to the wall of the secondary cabinet shell. I made sure that the holes didn't line up, and the wires/cables were kind of encased in foam as they went from one place to another.








Mic cable on the left, coming out of a 7/8" hole, and speaker wire on the right. The speaker wires ended up getting connected to an electro socket (like on a telecaster) so that hole got closed up and is where I plug the speaker cable into the cab. I didn't really have a great idea for the mic cable, so I just snaked a really long mic cable into the cab, as a sort of semi-permanent fixture. At some point I'll come up with a better solution and actually have an XLR plug on the side of the cab, but this gets the job done.








Top-down view of "Iso Cab Mk. II" with the top(s) open, so you can see a good cross-section of the foamy areas, and the Rivera-inspired venting tunnels (which pretty much got plugged up by the second shell, but it didn't seem to really change how it sounded)








I used threaded brass inserts for the lid(s) of the cabinet, because MDF strips faster than *insert some sort of horribly offensive analogy here*








They're a real pain in the ass to install straight with a regular flat-head screwdriver, and the brass itself is so soft that you can just absolutely MANGLE these things (which are actually a little spendy) and while you can buy a special tool for the job, they're also a bit spendy, so I just made my own from a really crummy old screwdriver that was laying around. (not the best picture, but basically you can see that it has a thin "probe" part that keeps it aligned, and then the actual "driver" part works like normal.)








The lid of "inner shell" closed, with big metal washers and 8-32 machine screws.








And finally, the "outer shell" closed up, and ready to rock and/or roll all night long (and possibly for a small portion of the day, provided it's a weekend or a national holiday) The brackets are screwed directly into the top lid, and the sides use the same threaded-inserts and 8-32 machine screw method to attach to the outer shell itself.








Things I learned: It takes a LOT of foam to dampen sound, and layers help. Almost everything about this project was easier said than done, but I'm reasonably happy with the results. Having never used another iso cab, I don't know how it compares in terms of absolute sound reduction, but I do know that price-wise, it beat out some of the competition by quite a bit. (And frankly, most of the competition don't sound that hot from listening to the YouTube demos I found, even the ones produced by the manufacturers.)

Cost Comparison:
Rivera: $1,000
Demeter: $650
AxeTrak: $420
Randall: $400
Jet City: $350

DIY: About $550 total.

$180 MDF
$100 Foam
$75 Speaker
$150 Mic (got a deal on it)
And then misc cables/hardware/etc...

Of course, if you have to buy things like a soldering iron and screwdrivers, then there's that to tack onto the price... But also consider the fact that I have a shitload of foam and MDF left over because I bought way more than I had thought I needed. Dunno how that happened.

And if I had it to do over again, I could do plenty of things to not only improve the design, but also to cut costs.

I designed the snaking venty tunnels to try and reduce the "boxy" sound that so many of the iso cabs have, but after this project, I'm fairly convinced that if your main chamber is large enough, that probably won't happen too bad. I left a 20x20x20" square for the speaker/mic to be in, and some of the really crappy sounding iso cabs have much smaller chambers. When you factor in the space of the venting tunnels, it probably doubled the total airspace it has.

Another thing that I learned is that MDF is FREAKING HEAVY!

It took a herculean effort to get the unloaded and half-finished inner cabinet up the stairs, and there's literally no way I could ever move this thing downstairs while it's fully assembled. It's going to live in my upstairs office/studio space for a long time, or it will die a painful death being removed.

I'll get some audio clips this week and post 'em up so you can all hear what it sounds like!


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## RickyCigs (Sep 16, 2013)

yes mdf is heavy as hell because of how dense it is lol. it looks like it will do the job just nicely. you should do an a/b comparison of it closed and with the lid off. then you can give yourself an idea of how "boxy" it may or may not make it sound. 

which is slightly ironic that everyone wants a box to not sound boxy.... maybe someone should design an iso tube lol it might make your tube amp more "tubey" 

more seriously, good work. hope it serves you well!


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## Pikka Bird (Sep 16, 2013)

^Or make it from glass to enhance the "glassy" tones. 

Looking forward to some demos, please.  This got me all fired up at the prospect of trying to build one for myself one fine day.


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## Wrecklyss (Sep 16, 2013)

I think a lot of the boxiness from most iso cabs comes from there being a dense pocket of air on both sides of the speaker cone. In a closed back cabinet there is only that type of pocket on one side of the cone, in an open back there is none at all allowing greater excursion of the cone. The tunnel system you built in give the cone more give on one side of the other which in theory should allow it to sound more like a closed back cabinet than an iso cab. I can see how that design would not, in fact, isolate very well, but with your double layer design it would be interesting to hear how it turns out.


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## KhzDonut (Sep 28, 2013)

At long last the cabinet is complete and recording has been finished. I give you:

THE EXAMPLE!





All relevant info about settings/gear can be found in the video description. I still want to dial in a slightly less harsh sound, while still retaining bite, so I'll fiddle knobs for a week or two more and if I don't get it perfect I'll start trying out a couple new speakers. Eminence Texas Heat is first on the list of things to try 

I'll go ahead and update this page if I alter the cab further.


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## Devyn Eclipse Nav (Sep 28, 2013)

Good lord, man, please re-upload that with a higher quality than 144p.

However it doesn't sound boxxy to me, so you succeeded!


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## KhzDonut (Sep 29, 2013)

Zeno said:


> Good lord, man, please re-upload that with a higher quality than 144p.
> 
> However it doesn't sound boxxy to me, so you succeeded!



I uploaded it at 720p, so you should be able to switch it to higher than 144p. It's working for me as of this post, but YouTube might have been having a problem earlier.

But thanks for the non-boxy comment, I'm glad to hear it  Hopefully it sounds even more not-boxy to you if you can get it to work at 720p


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## Devyn Eclipse Nav (Sep 29, 2013)

Nope, only giving me options for Auto and 144p


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## KhzDonut (Sep 29, 2013)

Zeno said:


> Nope, only giving me options for Auto and 144p



How weird. Maybe it hasn't properly propagated across the servers... I can set it to 720p right now. Sorry about that. I hope that clears up soon


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## Devyn Eclipse Nav (Sep 29, 2013)

We're all good now! I can get to 720p


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## TRENCHLORD (Sep 29, 2013)

Don't change speaker just build another one for your right-side track. lol
Great build, would love to do this myself someday.


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## Pikka Bird (Sep 29, 2013)

Sounds very good! How quiet is it outside?


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## KhzDonut (Sep 30, 2013)

Zeno said:


> We're all good now! I can get to 720p



Awesome! That's a relief.



TRENCHLORD said:


> Don't change speaker just build another one for your right-side track. lol.



I'd be lying if I said I hadn't considered it  Unfortunately, my wallet is pretty empty at this point, so that'll have to wait.



Pikka Bird said:


> Sounds very good! How quiet is it outside?



Well, it's quiet and it's not-so-quiet. Just "in the room" noise with the amp at 2-3 is very tolerable. It's just sort of a low-mid rumble, and some low-end thump when you really chug the low notes (especially on the 7th string)

The real problem is that it was pumping a lot of vibrations into the floor, and I'm on the 2nd floor. My wife would be downstairs and it was kind of driving her nuts, so I put the whole unit on top of all the left over carpet padding foam from building that damned thing and now it's much better. Probably only have the master volume at 1 or 2 right now (damn Mini Recto's don't have numbers on the faceplate) so in the room it's really quiet, and through the floor it's pretty quiet.

I don't think I could crank this thing past 5 without the noise through the floor being a problem for the neighbors (apartment), as well as just being too noisy in the room to be good for recording. I'll call it a success, but I'm interested in how the other iso cabs maintain such (apparently) low volumes when cranked. Perhaps that's just YouTube magic?


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## Wrecklyss (Oct 1, 2013)

ISO cabs aren't silent, just significantly quieter on the outside. Lower frequencies are the most present outside the box as the only thing that will calm those down is lots of density resulting in LOTS of weight. Maybe if you completey covered the outside in 60lb sand bags it would be silent, but that's wildly impractical.

Sounds like you built an ISO cab!


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## MF_Kitten (Oct 2, 2013)

You should get a ton of high density rockwool for the low frequencies, and figure out how to decouple it from the floor better.


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## RickyCigs (Oct 2, 2013)

You could probably also try using the isolation pads for studio monitors. One in each corner would probably help quite a bit. Pretty sure there are bigger ones for studio subs as well.


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## Sam MJ (Oct 10, 2013)

Good job, the clip sounds great. 


The problem with ISO cabs is that they're just fundamentally impractical. 

You're trying to build a small portable sound proof box and that just isn't going to happen. It's a contradiction in terms. 


You can build a small portable iso cab but it won't be very sound proofed *or* you can build a soundproofed box but it will be neither light, small or portable, because you need mass and decoupling to stop sound.

After that you then have to deal with the sound that's no longer escaping the box and do some serious treatment which again, takes up room (unless you want it to sound like a speaker in a box ).

If you look at the soundproofing that's used in professional studios you'll notice that most of the wall designs are a good foot thick and give around 50-60db of attenation. Pretty impressive and that would cut a cranked tube amplifier down to the level of a quiet conversation but if you built an iso cab based on that, the box would pretty much have to be 4 foot cubed! Unless you intend on using concrete! 


Tricky things ISO cabs!


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