This is a large speaker coffin configuration, 6'x4'x3'. It's a cabinet isolation box containing a conventional 4x12 cab or other large cab or amp. Goals:
Use 1.5" thick particle board (as thick and as many layers of wood as you can afford) (multiple layers is more complex, especially the door setup) The common stores do not have 1.5" particle board or MDF. I found 1" p.board at a common store but even this is hard to find. You should call around to locate an outlet for this material.
Make it around 6' long, 3.75' tall, 3' deep - check what size is required for a 4x12 cabinet. Bigger sounds better. (This is a "speaker coffin" shape.)
Set the structure on foam, to float 4" off the floor.
Line the inner surface with egg mattress or sound absorber.
On the front right, cut a hole bigger than the side of a 4x12 cab (the hole must extend to near the bottom, to enable sliding the cab or amp in and out).
On the front middle, cut a 2'x2' hole to access the mics and the amp controls.
Make a simple door that fits over the amp/cab access hole.
Make a simple door that fits over the mic access hole.
Put each door on 2 hinges. (Very simple hinges - 2 rectangles, piano hinge, 3 holes in each rectangle, $2 each)
Attach a latch on each door. I didn't have a chance to find a latch type at the hardware store -- ideally, it would have a little clamping effect.
Consider thin rubber seal around each door - not thick, else you would get a passive subwoofer effect.
On the bottom of the amp/cab access door, cut a notch for cable passthrough (guitar cable, spk cable, close-mic cable, far-mic cable). Put a small piece of thick foam insulation at this notch.
The far mic is a condenser mic, on a mini-boom. (Issue: mic clipping, mic power supply: battery sucks, phantom power is the only serious way to go)
The close mic is a dynamic mic, on a mini-boom.
The mic-access door also serves as an adjustable direct- listening hole.
Optional: add a 2nd cab/amp access door on the left (could cause leakage though - but could make interesting listening portal or other options)
Parts:
particle board sheets including doors
egg mattress
foam supports
long sheetrock screws
2 latches
4 hinges & medium sheetrock screws
Tools:
Makita battery-powered drill ($90)
Electric hand jigsaw
Screwdriver tips
Utility knife for foam
Contents:
guitar speaker
cab and speaker cable
optional amp and guitar cable, optional 2-direct-box setup
dynamic mic and miniboom and cable
optional condenser mic and miniboom and cable
Complementary studio gear:
mixer with phantom power for condenser mic
monitor amp
monitor speakers
long mic cables
long speaker cable
parametric EQ for post-mic, to compensate for cramped box sound
Ideally, put this box in a closet, basement, or separate room.
My 2-layer iso box has a bigger internal space than the Demeter Silent Speaker Chamber. I had much better results with it yesterday than my previous trials: this time the amp had new tubes and I used an SM57 on a miniboom (too large a mic stand; need much smaller one for this size of box - wasn't able to position the mic on-axis). But for anything less than a huge box containing a 4x12 cabinet, you *will* need to do post-mic EQ.
I got such good results that building a huge box is a lower priority, and I am enjoying the extra attenuation of two nested layers of wood -- which is then put in a concrete-brick-lined basement darkroom/utility room, which is the underside of the porch. I can still hear so much bass leaking into my headphones in the basement "control room", from the iso box low-end leakage, I always end up with too little bass on my recorded track. I look forward to somehow running the mic and speaker cable from the basement up to the main floor, so that my EQ in my monitors is not thrown off by bass leakage, producing too little bass upon playback.
The iso box has been a tremendous help in Tone research -- I quickly learned a lot about the character and balance of preamp distortion and power-tube saturation, along with gain levels and EQ curves at the 3 key points sandwiching preamp distortion and power-tube saturation.
Ultimate speaker cabinet isolation box
Not portable, but can be broken down into sheets, moved, and re-assembled.
A portable version would be a cross between this and the Demeter Silent Speaker Chamber. Best weight/size/attenuation balance is probably with single thick layer. Thicker walls than the SSC, for more attenuation. A longer cab than the SSC, for more bass and open frequency response. The SSC is a good light and compact design. It would be good to also have a heavy and big portable iso box, perhaps with 2x12 cab in it.
You can order a flight case to contain a 4x12 cab, mic, and air in front. A speaker is required for dynamics and filtering. The dynamics are called "air" and it is essential that you include enough air space in the box, if you are trying for a full-spectrum classic response. My current iso box, I tested with door open and closed. The difference, heard on playback of miked signal, is that there is more and deeper bass with the door open. So, bigger or longer ibox = more bass.
Speaker isolation box design
Goals:
provide authentic cranked amp tone for home studio or playing rock guitar at home
neighbors cannot hear it
housemates can only hear it a little
simple and easy to build
cheap
provides quick access
big size for open sound
fits any room (such as in a closet)
easily disassembled
Use 1.5" thick particle board
Make it around 6' long, 3.75' tall, 3' deep. Bigger sounds better.
Set the structure on foam, to float 4" off the floor.
Line the inner surface with egg mattress or sound absorber.
On the front right, cut a hole bigger than the side of a 4x12 cab (the hole must extend to near the bottom, to enable sliding the cab or amp in and out).
On the front middle, cut a 2'x2' hole to access the mics and the amp controls.
Make a simple door that fits over the amp/cab access hole.
Make a simple door that fits over the mic access hole.
Put the doors on hinges.
Attach a latch on each door.
On the bottom of the amp/cab access door, cut 4 notches for cable passthrough (guitar cable, spk cable, close-mic cable, far-mic cable).
The far mic is a condenser mic, on a mini-boom.
The close mic is a dynamic mic, on a mini-boom.
The mic-access door also serves as an adjustable direct-listening hole.
optional: 2nd amp/cab access door on the left
Parts:
particle board sheets including doors
egg mattress
foam supports
long sheetrock screws
2 latches
4 hinges & medium sheetrock screws
Tools:
drill, hole cutter, screwdriver tips
small saw, large saw
utility knife
Contents:
guitar speaker
cab and speaker cable
optional amp and guitar cable, optional 2-direct-box setup
dynamic mic and miniboom and cable
optional condenser mic and miniboom and cable
Complementary studio gear:
mixer
monitor amp
monitor speakers
long mic cables
long speaker cable
Ideally, put this box in a closet, basement, or separate room.
If you are sizing this box to be contained in an existing closet or utility room, be sure to consider construction logistics: will the pieces fit through the door? Will you have room to insert the screwdriver? will their be enough depth for a 4x12 cab given these construction elbow-room requirements? You can also do other construction techniques such as braces for internal fastening rather than external fastening of the 6 sides.
Consider access logistics for the doors: will you be able to slide out a 4x12 cab? will you be able to access the amp controls, close mic positioning, far-mic positioning? Consider doors on top and front.
Amptone.com ultra gear-search page