Rethinking isolation cabs, where does "boxy" come from?

[Kapo_Polenton]

So my initial experiment with roxul wall panels/baffles set on the floor tented around a cab provided me with the ability to see that I can def turn the amp up to levels I would not be able to otherwise do with anyone in the house. The problem however, is that it still generates a hell of a lot of noise and I am only at about 4 on the master volume of my 2204.

So I spent a day or two researching DIY and commercial offerings of iso cabs on youtube and the net. Seems to me, the "boxiness" I hear between open and closed lid on some designs is not as drastic as I hear in others, and that most iso cabs that are available commercially, line the box with that cheapo black foam which does nothing for bass frequencies. So combine, no bass frequency filtering with the proximity of adjacent walls and reflective wall in front of the speaker, is this what results in that "boxy" sound?

Some of the other designs that use:

-decoupling the cab from the floor

-thicker rigid insulation in place of foam

- no 90 degree corners in the box for corners facing the speaker

- a larger space than say the standard Randall or Jet City iso box

all seem to me to breathe better.

So I ask the question, does controlling the frequencies with better absorption go further in taming the apparent boxiness because it removes perceived bass or does that boxiness just result because too much air is being pushed forward with nowhere to go? To me it sounds like the debate between sticking carpet and foam on the walls of a home studio vs. using proper bass trapping in the corners and reflective panels on the wall. I know my basement studio space sounded night and day with panels in the corner and on the walls.

Thoughts?

 

[Kapo_Polenton]

Don't be shy, let's learn and discuss so that we can build a better box! We could call it the "Lightning Box"...(TM)!

 

[Anonymous]

The box I have works great and it is held together by velcro so you can easy assemble/disassemble to move it into a room or closet. While I paid $800 for it shipped to my place (from vocalbooth.com), it could be built much cheaper if you are handy (which I am not, nor did I have the time).

Here are some pictures of mine if it helps at all:

For what it's worth, almost all the real amp clips on my music page (sig), including my Mojave PeaceMaker clips were recorded in that iso cab and they don't sound boxy at all. And I had that 100W PeaceMaker completely cranked with the volume on 10... I think it may be that people are overthinking the "boxiness" thing when close micing a 100W cranked amp in one of these boxes...

Steve

 

[jkkkjkhk]

I could be wrong, I don't have any experience with iso cabs, but wouldn't having the cab sealed and no port to release the pressure be part of the problem? I believe Rivera attempted to fix that issue, don't know if theirs works better or not.

 

[Kapo_Polenton]

Yeah the silent sister but come on, close to 1k for that thing? Forget about it. I think that roxul rigid insulation would probably work better than foam as it has better bass absorption frequencies. Thanks for the pics of the 4x12 though. I am looking at mic'ing a 2x12 with only one speaker in it so it gives me an idea of how much space i might need inside the box. Almost room for two back to back cabs there looks like. Could be a weekend project. The pic below is what I have been messing around with. Still pretty loud though with the amp on 4 or 5 and the sweet spot for me is MV at 7.

Steve, those clips on your site sound great to my ears. Definitely not lacking any bite or highs which you sometimes hear in smaller boxes.

 

[fearhk213]

I totally hear you. So many look like no real thought was put into their design and just sound flat out bad in the clips I've heard. I imagine using better absorption would help, but in the little research I've done on that stuff I imagine you'd have to go pretty heavy with the absorption because the speaker is firing into a small square or rectangle, and parallel walls are nightmares for those low frequencies. A couple of other factors too are the pressure build up and driving the speaker unusually hard, both which will affect how the speaker reacts and sounds. Letting some of that air escape would help, and either going a bit more conservative on the volume or using an attenuator or tame the amp would help too. Using an ISO cab is always going to be a compromise compared to miking a 4x12, but I think rigid fiberglass, letting some air escape, and using an attenuator would be the way to go.

The two ISO boxes that have sounded most impressive to me in clips are the Rivera Silent Sister and the new Randall ISO412. The Rivera lets the air escape (that's their big sales pitch haha) and it looks like it may actually use real absorption based on the pictures I've seen, but I'm 100% sure on that. I hear ya on the price. The Randall looks like it only has that foam stuff, but it sounds pretty good in the clips I've heard and it much cheaper. The only ones I've heard were done by Ola in some of his amp demos, but they don't scream ISO cab to me at all, so they're doing something right. I don't know if that ones lets air escape, though. Maybe the fact that it's in a large enclosure helps too.

 

[paulyc]

I have the Rivera box...don't waste your time. It sounds boxy to me, although I don't like digital recording anyway...I'd much rather record to tape for the sound, but it's LOTS of extra work. I think digital sounds boxy. The Rivera really doesn't cut level as much as you would think. I have an actual iso booth/room I built in my basement with double walls, air lock type double doors, etc...and the Rivera box is just as loud with the door closed as it is open, most of my attenuation comes from the actual room I built under/next to my stairs. I can crank the amp pretty good even without the Rivera box. I also have a Marshall cabinet simulator/power brake that I can use to tame volume and take a direct cabinet emulated line out from direct into the console.

 

[Kapo_Polenton]

Hey Paulyc, do you have any pics of your setup? trying to understand how large/small this room that you built actually is?

Overall, I think the Randall 4x12 design works because as mentioned, more room/air for sound and pressure to travel before it hits the microphone again. These tiny box designs regardless of letting a bit of air escape if they are ported, just can't do the trick.

 

[paulyc]

I don't have pics, but it looks like a closet next to a stairway that does a 90* turn as it goes down, so there is empty space under the stairs next to a closet. I put up soundboard (that brown stuff they sell at Home Depot) with double layers of unequal thickness sheet rock on double walls (there is a 4" air gap between them) and stuffed them full of fiberglass insulation, the ceiling has double layers of sheet rock and fiberglass too. There is carpet on the floor, and the walls are lined with industrial foam (from Granger Industrial Supply). The doors are just well sealed exterior grade pre-hung commercial doors from Home Depot. I have a cable box that contains 3 XLR mic connectors, 3 1/4" speaker jacks, and a couple of 1/4" headphone jacks for moving the mic around to the sweet spot and doing vocals. I can put any 100 watt amp up on 10 and you just hear the lows slightly bleeding through the walls, but if the studio monitors are up loud enough it's not an issue (or if you wear headphones). I thought the Rivera would make it really silent...but no dice. I applied caulking to all gaps or spray foam insulation to try and make it really soundproof, but I just didn't have the ceiling height to make a true room within a room system. I'll try to post up measurements and/or pics of it. If a Marshall style amp is around 2.5 or 3 on the master you don't really hear it too much.
The last piece of this puzzle is a good exterior type solid door for the doorway to come down the stairs to the basement that is weather stripped to try and stop noise from going upstairs...it gets pretty loud on the first floor, wasn't a problem until I got married. LOL.

I bought a couple of Egnater 1x12 cabs (used) to stick in the cubby hole under the stairs and loaded them with different Celestion speakers (V30, Greenback, 90 watt, Vox Blue, etc...) for experiments.

The last thing to consider is that removing bass frequencies from the amp (either with the bass knob) or a graphic or parametric EQ in the loop will go a LONG way in combating the loudness of the amp (it's MUCH harder to stop transmission of low frequencies than high ones). You're going to remove a shitload of lows when you mix anyway because the guitars will be muddy and get in the way of the bass and drums. Let the bass and drums make the track heavy, that's what they're there for. All the 80s guys are recorded this way, with the mids humped up and the lows cut...

 

[steve_k]

This will probably be of absolutely no help....but, I had (have) a Randall ISO Shitbox. The V30 that came with it was just that---boxy and sounded like shit. I put the thing away for awhile and used the Two Notes instead. But, I got it out a few weeks back just to check out again. I ended up destroying the V30 in it and replaced it with a new EV Classic 200W speaker. Also, put some egg crate material in the bottom and sides of the lower part of the cab. I will say this made some noticeable improvement. The boxy sounds are gone and almost back to a normal EQ out of a PA system, with just a bit of work. Almost any mic sounded better than a SM57. No doubt, building a box to sit your favorite 412 in and big enough to allow some air to move without reflection is going to be the better option. Would like to build one some day from a road case.

Check out the Hermit cabs. Not sure if that guy is in business anymore. He didn't answer me back.

So, I moved on to the Mesa Cab Clone which is to me the optimal live sound solution - depending on the amp and output tone you are after.


Steve

 

[paulyc]

That's some camel toe !

 

[paulyc]

.

 

[Kapo_Polenton]

That's some camel toe !

+1. Can't say it bugged me in the slightest though

 

[paulyc]

Not at all !

 

[syncrodude007]

on the toe...
doesn't Jerry Cantrell use an 4 x 12 ATA iso cab off stage...

 

[steve_k]

That's some camel toe !

+1. Can't say it bugged me in the slightest though

ISO Toe

 

[Kapo_Polenton]

I'm considering going with this design but adding all the rigid isulation into the sides rather than the foam: http://www.amptone.com/diyisobox.htm . I'll probably also build out the corners so there is no bass building in the corners. Had it going pretty loud again and my design with the baffles only just won't cut it. Still too much noise going in the small basement. As most of us know living with GF's or wives, the ability to record at what we consider to be acceptable levels, seems to be anything but that to them. I think 1 on the MV is considered too loud.

 

[Anonymous]

I'm considering going with this design but adding all the rigid isulation into the sides rather than the foam: http://www.amptone.com/diyisobox.htm . I'll probably also build out the corners so there is no bass building in the corners. Had it going pretty loud again and my design with the baffles only just won't cut it. Still too much noise going in the small basement. As most of us know living with GF's or wives, the ability to record at what we consider to be acceptable levels, seems to be anything but that to them. I think 1 on the MV is considered too loud.

With my iso cab with a cranked 100W plexi clone, the noise outside the box is significant, especially bass, if it were to just sit out in a room. It would be unbearable for others living in the house, frankly.

What I did was put the iso cab in a closet under some stairs across from my control room and buy long mic and speaker cables to run to my recording system and head in the control room. With the closet door closed, you can still hear some guitar (again mostly bass), but my wife can watch TV at normal volumes in our adjacent family room while I'm recording. The one issue is that the walls shake from the volume in the closet, which is a bit unnerving for the other occupants

I think that is the best you can expect to do if you crank a loud amp in the box...

Steve

 

[paulyc]

I have some friends that did their own demo back in the 90s on Tascam DA88s and their solution to recording in the basement was 4 old mattresses and some really heavy packing blankets made into a box around the 4x12 cab...this was the best solution I've heard. It was Ibanez Jem into ADA MP-1 into the effects return of a Marshall JCM 800 head, and it was ripping loud inside the mattress "box" but completely liveable outside of it.

 

[shadow070]

My experience is also a boxy sound and thats why i left the iso-cab route. I think, the air hits the walls surrounded, freq. hit each other what results in that sound. Well, thats what i think.
If you can let some air escape and have a bigger iso-cab could be the solution but then again, sound will escape and that will defeat the purpose off having one.

(i dont have any background in frequencies and/or construction its just my personal take on the matter)

I have some designs some place but gave up because of time. I was checking out soundwaves/frequancies(how they work), how they react on surtan materials and what not.

Hope you get to figure it out, its a market.