Building a 1x12 Thiele/Small guitar cabinet.

[Monkus]

I need a cab for an amp head I'm getting so ima gonna build one. Its based on the plans found here of the EV TL806:

http://archives.telex.com/archives/E...ders Plans.pdf

Seems like Mesa Boogie's cabs are based on this design. I know zilch about woodwork so I enlisted a family member to assist, well. to 'get 'er done' and I'll provide moral support. The handiwork is his, I'm just the helper.

I'm using MDF and pressure treated, dressed white pine for the braces on the inside. Cut the pieces yesterday, glued and nailed the enclosure together. BTW a nail gun is a wonderful thing. Clamped it and left it overnight, going back to do some more stuff on it after work today.

Pics:

Showing the back... I learnt yesterday that those are "sash clamps'.



The knife was used to gently scrape the excess glue from the corners. Thats where the braces will go. The small white boxes are the 'ammo' for the nail gun.



Shot of the inside. Disclaimer: Photos were done with my phone.



Mods: First time I'm posting pics from photobucket so feel free to modify them.

More to follow...

[Monkus]

Started putting in the internal bracing yesterday, nail, glue, wipe excess. We found that we were 1/16" off on the internal volume, we'll see what that does with the sound.



Fitting in the bracing for the ports, ready to glue. The flat piece in front is a removable port cover. You can use the cab with or without it depending on your preference.




Incidentally my cousin (the carpenter) called me this morning to tell me that he was going to work on it. He has a Gov't job, and home at 10:00 a.m.

[bcdon***]

Wow, looking really good. Bet it will sound great with the Boogie.

[Monkus]

Thanks bcdon, lets hope it sounds good!

After intensive research and invaluable comments from Tung and Tig...(thanks guys)!

I decided on an Eminence Delta 12A Speaker for the cab. The thing is, its rated at 400W RMS, 800 peak, which flies in the face of all conventional wisdom.

Specs on the Delta here:

http://www.eminence.com/pdf/Delta_12A.pdf

From my googling, this seems to be ideal replacement for the EVM12L. It also seems that this speaker will not color the sound of an amp and has a 'better' sound than the EVM12 L which the speaker enclosure was designed for. Locally, I got one new for about $50 so what the heck, I'll try it. I need to figure out how to "break" in a speaker with a 9 volt battery.

On to the pics!

Internal bracing finished, including port area.




Cleaned up a little and from another angle. You can't see it very well. but the edges have been routed to a rounded edge.

[tunghaichuan***]

From my googling, this seems to be ideal replacement for the EVM12L. It also seems that this speaker will not color the sound of an amp and has a 'better' sound than the EVM12 L which the speaker enclosure was designed for. Locally, I got one new for about $50 so what the heck, I'll try it. I need to figure out how to "break" in a speaker with a 9 volt battery.

I wouldn't use a 9v battery, it is DC and could possibly overhead the voice coil. You need and AC source like a wall wart, a filament transformer or Variac.

The formula for figuring out the amount of wattage a particular voltage level will generate is V(squared)/R or ac voltage squared divided by the speaker's resistance. If you want to get technical, you should measure the DC resistance of the coil, which should be around 6.3 ohms for a speaker with an 8 ohm nominal impedance rating according to the Delta specs .pdf.

So for 25VAC, you get 25*25/6.3=99.2 watts. You may want to try lower AC voltage, even though the Delta is rated for 400 watts. The more wattage you put into the speaker, the louder it will be and that 60HZ tone will drive you nuts.

Looking at the specs for both the Delta 12A and the EVM 12L, the Thiele specs are close but not identical. I bet the Delta sounds fine. I'll be very interested as my Thiele cabs are loaded with Celestions, but I'd like to hear them with Delta speakers.

HTH.

[bcdon***]

I wouldn't use a 9v battery, it is DC and could possibly overhead the voice coil. You need and AC source like a wall wart, a filament transformer or Variac.

What is the purpose of this 'break-in' ? Are all speakers broke-in is some fashion or another (e.g. stereo speakers, tv speakers, &c)?

[tunghaichuan***]

What is the purpose of this 'break-in' ? Are all speakers broke-in is some fashion or another (e.g. stereo speakers, tv speakers, &c)?

The break in loosens up the parts. The consensus is that speakers sound better after being broken in. Some speakers can sound shrill and "stiff" and breaking them in can tame the ragged high end. This article explains it better than I can:

http://www.premierguitar.com/Magazin..._Speakers.aspx

Stereo speakers are a different animal. They have synthetic cones and surrounds, which do not loosen up over time like the paper cones in guitar speakers. Stereo speakers are typically played clean with no distortion in the signal, their purpose is to reproduce recorded sound. Guitar speakers generate music and there can be lots of harmonic distortion in the signal.

[Monkus]

From what I've read so far, it depends. Some speakers might have a brittle edge to them because of the components, stiffness as a result of the manufacturing process or any amount of other reasons. As the cone and coil moves, they relax within tolerances over time. Some might not. I guess the questions are: Do you want the broken in tone faster, or do you want to enjoy the entire breaking in process of the new speaker? Some more experienced fretters may chime in on this. The article from PG linked above explains it really well.

Personally, I would like the broken in tone of the speaker as fast as I can so I can evaluate my amp easily. May not be necessary but might be worth looking into.

FWIW.

[bcdon***]

Breaking in makes sense, I just had never heard of it before... there are so many tricks of the trade out there.

Thanks for the explanation guys!

BTW, Monkus.. looking forward to the next round of pictures. :-)

[tunghaichuan***]

Breaking in makes sense, I just had never heard of it before... there are so many tricks of the trade out there.

Thanks for the explanation guys!

Breaking a speaker in can also take a marginal or bad sounding speaker and improve the tone. I know an amp tech who had this particularly bad sounding speaker. He hooked it up to a sine wave generator and left it on over the weekend. He said it improved the tone dramatically.

Some speakers sound terrible when new, breaking them in can improve the tone up front without having to play through it a lot to get it broken in.

[Monkus]

No pics today because nothing was done to the enclosure yesterday. Ran around getting the speaker, fiberglass insulation, silicone sealant and more box corners. I forgot that a cube has 8 corners, not four. Planning to paint the inside of the enclosure today, cut out the baffle, make the grille and mark the drill holes for mounting the speaker and handle. On Saturday, we'll tolex the enclosure, install the wiring and mount the baffle with speaker. At least, that's the plan.

[Monkus]

Outside of Delta 12A speaker packaging. The speaker was secured in the expandable foam stuff, snug and well protected.





Rechecking the measurements for the baffle cutout. I originally had an Eminence Valtech 12" lying around and was going to use that before lucking into the Delta. We had first used that for the markings on the baffle cutout. He's remarking them here.




Planning to countersink the speaker so that its flush with the front of the baffle. I'm thinking that's what he's measuring here.

[tunghaichuan***]

FWIW, the speakers on my cabs are front mounted, held in place by large brackets that bolt down.

Here are a couple of pix:



http://www.thefret.net/album.php?alb...achmentid=2278

http://www.thefret.net/album.php?alb...achmentid=2277

The grill is expanded metal held in place by sheet rock screws, counter sunk washers, and rubber feet (used as spacers).

[Monkus]

@Tung: Thanks for the links! We're screwing it down as the speaker has 8 screw holes, on to the baffle plate. Thanks for the spacer idea, we're using scrap pine cut to size for the spacers and attaching velcro or upholstery tabs to them to secure the grille.

Sanding down the baffle, speaker hole already cut out. There's a story here, He had a fancy schmancy tool with a jig. We spent an hour yesterday figuring it out, but when he tried to use it, it was all wobbly. Went back to the old fashioned jigsaw to cut the hole.




Painted the internal ports with chalkboard paint.




Routing the countersink for the jackplate.




Finished countersink showing the jack plate (white). Incidentally, the jackplate was part of a 6" pvc pipe that he flattened with a heatgun between two heated tiles. Couldn't find an appropriate jackplate locally. Wondering if the plate will collect enough static electricity to add hum?

[Monkus]

Painting the grille baffle.




Offering up the speaker and grille baffle for fabric clearances.




Mrs. Carpenter showing us how to place the piping.




Settled on the piping placement.



The blue glow of thunder from the amp requires a blue bolt of lightning, the only reason for piping. We cut the tolex and hung it out to sun warm. The grill cloth was also set out. Started wiring the speaker wire to the jackplate.

[Monkus]

Attached the grille cloth to the baffle.




Dry fit into enclosure.

[Monkus]

Starting the tolex job on the enclosure. Not liking the tolex choice here.




Finished tolex enclosure. Tolex looking ok----ish




Dry fit the speaker baffle and grille. Tolex looks fine.




Having some 'clearance' issues with the piping. The fit is a little too snug, so we decided to sleep on it. Not the piping, the issue, hoping a solution will come to us seeing we never did piping before. The amp is in the skybox!

[Monkus]

Wired the jacks to the speaker tabs.




Installed jackplate.




Installed cab handle.



Had to remove the grille cloth, sand the sides down a little to get clearance for the piping and re-install the grille cloth. Installed cab corners. Rechecking the piping clearance.

[bcdon***]

That looks really, really nice! When are you going to be able to plug it in?