Wide body Theile.

[Boogafunk]

actually the size (airspace) and the port tuning are equally important for the desired result from any given driver. otherwise you could pop a 15 or 18 in the smallest enclosure it would fit in and just tune the encolure to taste. smallest pa subs ever. the problem is they would sound horrible. now with guitar (midrange mostly) designs are a bit more forgiving. truth be told most manufacturers "calculate" the enclosure size of a cabinet based on the head that is designed to sit on it, and what proportions are pleasing to the eye. these designs work, and some work well, but they are not optimal. that is the difference between these older designs (because it looks cool) and a design like a thiele, with calculated airspace and porting, designed for a specific driver. again guitar sound is all about imperfection, almost the opposite of what any other speaker system strives for, and midrange reproduction is way more forgiving of cabinet design, than bass reproduction.

enough of the rant, you could make a "thiele" with a greater airspace and a the same port tuning, but it would have a different frequency response. i could model the response below 500hz but the rest would have to be field measured. you might love it or hate it, but it would definately be different.

oh, gts, you are right about the fact that the bracing might weight close to the weight savings for the light cab, unless i have a really ingenius idea about how to do it without making braces that look like violin braces, however a 1/2 ply box can be made every bit as sturdy and resonant free as a 3/4 box it would just take longer to build. i have a folded sub that i built out of 1/2" that is incredibly strong and resonant free. with an enclosure that is close to 13 cubic feet (ten thieles) the weight savings were enormous.

 

[trickyrick]

Hey trickyrick,

OK, makes sense in terms of speculation. But I am thinking of my own Thiele and know that badboy is heavy given its very modest dimensions ...yours would be even heavier, yet adds nothing to the sound quality as the added mass is dead space (or looks like it from the pics). Please understand that is absolutely NO criticism of your stellar workmanship ...I am simply putting forward thoughts on the subject.

I know my thiele is much deeper than my MKIII short head, for example. So if you made a Thiele wide enough to accomodate a wide head yet maintain the same exact volume, I would think (my guess, actually) the depth would still be ample to support the head/overall rig withou issue. What do you think? Maybe worth an experimental build of 1 unit and A/B your two units?? What's your material cost of one possible "testbed" cab?? ...maybe I could help you in that respect. PM me if you're seriously curious ('cause I am ).

Edward

I would be willing to make a prototype cab with the depth shallower to keep the overall CF at 1.3. Again, I am not an audio engineer and I don't know if it would make a difference of not. I would assume 1.3CF is the same within reason. A cabinet 4 feet long X 2 feet wide X only 2 inches deep would not sound the same as a square box. ( Don't quote those dimensions, I pulled them from my butt and didn't do the math) The only real way to tell is to A/B them. The Thiele is a designed cabinet that sounds great. Why mess with a good thing.

and as GTS said, it would make a great stash!!!!!

 

[trickyrick]

very nice work. looks quite professional. i have been contemplating a similar design myself, but i havent crunched the numbers yet. yes the thiele is a deceptivly heavy enclosure for its size. but most of that has to do with the weight of the evm12l. btw the new ones seem to be just a pinch lighter (haven't put them on the scale though) i would guess that the widebody version probably weighs somewhere around 5-7 pounds heavier than the standard. i have contemplated making a lightweight version of the thiele with 1/2 inch ply with internal bracing, but i am still undecided because i just don't know if the weight savings will amount to enough to be worth it.

rick, any reason you decided to make the back removable, other than that's the way that mesa does it. are you planning on rear loading the speaker? also i think your price is not bad at all. i hope you get some buisiness. (maby it will make people realize how much actually goes into the construction of these cabs, especially for folks who don't have factories and assembly lines.)

Thank You Boogafunk compliments from a fellow woodworker are always great. Personally I am not that concerned with the weight. I don't gig much anymore ( Although I would like to ) so I don't move the cabs around. If you notice in the photos, the driver hole favors the port side of the cabinet. I did this to try and compansate the extra weight of the additional 5 inches of cab as well as the dummy wall and spacers. I didn't spend too much time calculating, but my intention is to be able to set a handle dead center but favor the back and have all of the weight evenly distributed throughout the box.

I think I made a removable back because I would prefer to pull off the back as opposed to pulling the speaker which I am front loading. Also, I think it will look neater without exposed tolex seems on the back. I realize that it is the BACK of the cab, but it would really be a lot easier to apply the tolex.

I agree with you also, custom wood work is just that. A one man shop building high quality is always going to cost more then production line. There is something to be said about building them one at a time. Sound familur?

 

[trickyrick]

Absolutely beautiful. Nice enough to just varnish! Here's something to think about. You would be able to do away with the dead space and increase the internal air volume of the cab by simply proportionatly reducing the port area. Or tuning the enclosure. It is possible to make the cabinet anysize you want and then tune it to your driver by calculating the port vent area. Try this:http://www.ajdesigner.com/speaker/i...ive you great insite into the design of cabs.

Cool site, But again. It's a theile. I really don't want to redesign a good thing. Has anyone ever heard a bad theile with an EVM12L in it. I have never heard a 1 12 cabinet sound so full. I would rather lug a combo and a cab to a gig instead of a head and a 4 12 but thats just me.

I wish I had the time to experiment with different designs, remember, what sounds good to me may sound like poop to others.

Again, thank you very much for the kind words. I was going to pull my head and build an imbuya can and then a matching theile. When I got the amp I was suprised that it looked brand new, so i am leaving it as is. Maybe I will change my mind one day and do a head and 2 cabs out of exotic wood but for now I am content. Well I hope to be, I havn't applied the tolex yet, I could really F that up.

 

[trickyrick]

I'd think the 1/2" ply vs 3/4" would start to cause problems. If anything the bracing required to limit vibration would put the weight back where you start. It also might cause unintended wave form distrubances within the cab.
-------------------------------
One of the main things I think most people fail to understand with projects like this is the cutting and assembly is only half the effort (if that!). Finishing, meaning sanding, filling voids (if any), and doing tolex or if hardwood (pick your finish), also prep for and then adding hardware such as making the grille and adding cuts for jack plates etc etc is time consuming. Usually about half the total projects time is spent finishing.

So sure one nights work cutting and assembling to get the cab done but there's lots more to do before it's "finished". So yes Boogafunk maybe folks will realize how much goes into the construction of these and any other cab. Often (not always) until someone tries it themselves....
And having all the "proper" equip to put one of these together is not cheap investment. trickyrick (like many woodworkers) has some good money sunk into his shop tools.

I think most here on the board appreciate good craftsmanship and understand. That's why they are here, and why they own Mesa amps etc.

Sanding, I hate sanding. Sanding sucks!
Your right dude, a few hours to cut and build and several more to finish. That is always the way it's been and always the way it will be regardless of what technology comes our way. exp.I have a great drum sander. flattens glue ups quickly. However it takes a while to change out the grit of paper. So I go through 5 grits to get a nice smooth finish, I would rather just use my random orbit after running it through once on the coursest grit, just so I can do the work in less time. There is more physical effort but it gets done quicker. Go Figure. Sanding sucks, did I mention that.

 

[trickyrick]

I havn't applied the tolex yet, I could really F that up.

these might help
http://www.silvatone.bravepages.com/November/Build.htm
http://www.dafguitars.com/pages/212cab2.html

but you've likely done plastic laminate and worked with contact cement so you'll be fine.
pics of a re-tolex project in this thread might help too

http://forum.grailtone.com/viewtopic.php?t=16542

-g

Yeah, I was just pretty much kidding around, I have done it before. Thanks for the sites though.

 

[edward]

Hey trickyrick,

Yeah, the Thiele cab is an amazing piece of gear. And like you said, I'd much rather haul my puny little Thiele than a 212 (fugghetabout a 412). While I'm sure dramatic changes in dimensions would adversely affect the resonant frequency and overtones of the tuned cab, subtle changes may not alter the tone much ...how "much" is the question.
I was just speaking off the top of my head. The design as is really does seem to defy logic: how does something so small sound so huge!! So yeah, why mess with success. Especially since the weight savings I suggest would be modest at best. Again, superb work as I love seeing quality woodwork, especially in the raw!!

Edward

 

[racer*x*]

Looks great! im glad someone else has testified about the time and labor intensity of these projects. yours turned out awesome and your skills show. ill comment more later on the different sizes and one very important factor that boogie left out. Damping makes all the difference in the world!

 

[racer*x*]

just outa curiousity what diminsions did you use the ev spec or boogie spec? i noticed two different theories on our bracing, one suggested a poor mans joint and the other suggested braces break speaker pattern waveform distribution. IMHO boogie neglected the braceing because of a cost and time issue. we built ours according to evs spec, and you can bet the volume of those braces are figured in! granted there are tolerances in building enclosures, there are a lot of combos that will work, at some point you get to a diminishing returns situation, if your 5 % off here and 3% off here that starts adding up. the difference between a dampened cab and a non dampened is phenomenal! when you load yours try it both ways. I did and was amazed. now to each his own ear candy so you decide. but i can tell you the damping really smooths out the beaming characteristics of the evm12l. and grill open air space %'s make a difference too. the standard 8mm hole metal grill is 58% free air, the grills we use in one model are around 45% , this cuts the beaming as well. a grill cloth i suspect has a percentage of around 75% free air, although just a guess on my end, nothing scientific.
i definately respect the design you have used and im sure its gonna look great under your head. But heres my thought and this is for my personal needs and may only apply to me. your cab is going to be 50 % heavier(a guess btw)unloaded\a possibility the extra chamber will resonate , i m not sure what the chance is or if it would matter, but yet another small percentage in the whole scheme. from a production standpoint im not sure how the cut list works out, yet another small percentage and the whole balance thing youve touched on, good forthought btw.
In my situation i run two thieles , ev spec(because they designed the speaker) . pros to this are: any head or rack combo sits nicely, they can be arranged according to the room you are playing simply by putting them in different configurations for desired bass response. I am a pro player, not that im great, but i get paid so that makes me pro right? haha, anyway, point being different rooms require different configs. my take and maybe just mine is i run two cabs. itll smoke any 4 x12 on the planet, idividually they are lighter. if i need one i run 1 if i need two i run two, in the offchance situation i want to show out i take four! that has never happened BTW. two thieles are more than twice one thiele, i dont know the exact numbers but i would guess 1+1=3. thats what it sounds like anyway. im very hard on my gear , its in and outa trailers 3 times a week minimum. which is why we chose the spray coating vs. the tolex for our own. we do tolex and exotic hardwoods as well, but id never gigem!
in sumation, hehe, i like your design and if it works for you then even better. its very well constructed. try the 2" polyfill, you can get it at your local fabric outlet, its a 100 bucks a box or you can buy small cut sections. its dust and particle free and a little more dence than the 3 inch pink which is what most sealed enclosures used to use , but however would be stupid to use in an open config, unless you wanted the front row taking cold showers when they got home to iradicate the fiberglass fibers from there exposed limbs after the show!
Good luck and congrats
ScottieR

 

[JOEY B.]

your cab is going to be 50 % heavier(a guess btw)unloaded\a possibility the extra chamber will resonate.

Would filling the emptry false wall chamber with that spray can expanding foam help to prevent any resonance without adding much weight? Cut a small piece of scrap wood big enough to cover the hole. Drill a hole in it big enough to fit the nozzle of the spray can into. Then coat the underside with a non-stick material (crisco, etc.), screw it to the cabinet and fill 'er up. Just a thought :?:
.

 

[trickyrick]

To Racer X, I used the ev plan for inside dimensions only. I was looking for 1.3cf. I also used the cleat sizes for the ports. As far as the empty space, I would be shocked if it resonated. 13ply 3/4" maple aprox. 9"x11" Fully secured with poly glue and staples. I would be shocked if it did. However, It could resonate and give off a beautiful tone or sound like crap. There is only one way to find out. I will certainly post my personal opinions when it is covered and loaded. I ordered all of the hardware today and expect it monday, jacks, speaker wire, feet, etc. I will post pics when it is done.

As far as the braceing, It just didn't seem neccesary. the EV plans show all butt joints which suggested to me the braceing was for strength only.
Kind of like framing a house and applying sheathing over the framing.

Also, I probably will try the dampening meathod ev suggests. I used to own a front ported cab with 2 round port tubes that had a lot of dampening mat in it. I removed half of it once and it dramaticaly changed the tone of the cab. SO there is something to say about changing the volume that way. I will see when I see. Thanks.

 

[scottywompas]

That is great work. Definatley something us widebody combo guys wish we had. I'm not sure why Mesa doesn't make a widebody thiele. Maybe you can start a little business.

Scott

 

[Restless Rocks]

Absolutely beautiful. Nice enough to just varnish! Here's something to think about. You would be able to do away with the dead space and increase the internal air volume of the cab by simply proportionatly reducing the port area. Or tuning the enclosure. It is possible to make the cabinet anysize you want and then tune it to your driver by calculating the port vent area. Try this:http://www.ajdesigner.com/speaker/i...ive you great insite into the design of cabs.

Cool site, But again. It's a theile. I really don't want to redesign a good thing. Has anyone ever heard a bad theile with an EVM12L in it. I have never heard a 1 12 cabinet sound so full. I would rather lug a combo and a cab to a gig instead of a head and a 4 12 but thats just me.

I wish I had the time to experiment with different designs, remember, what sounds good to me may sound like poop to others.

Again, thank you very much for the kind words. I was going to pull my head and build an imbuya can and then a matching theile. When I got the amp I was suprised that it looked brand new, so i am leaving it as is. Maybe I will change my mind one day and do a head and 2 cabs out of exotic wood but for now I am content. Well I hope to be, I havn't applied the tolex yet, I could really F that up.

My point is it would still be a "theile". The Theile-Small formula can be inversely applied to the size of the enclosure using the specs for your desired driver. By taking EV's info and specs and plugging them into the calculator program then entering your box dimensions it is possible to "tune" the port area to have the cab produce the same resonant frequency as the smaller EV or Boogie 1.3cf cabinet. What we're looking at here is wheather or not to consider optimum cabinet dimensions as your priority or wheather to make the most portable cabinet size (as did Boogie). Wheather you're building a cab with internal air volume of 2cf or 1.3cf it would still be "theile" when you use the Theile-Small formula to calculate the port area to your desired resonant frequency for your driver of choice.

 

[trickyrick]

Absolutely beautiful. Nice enough to just varnish! Here's something to think about. You would be able to do away with the dead space and increase the internal air volume of the cab by simply proportionatly reducing the port area. Or tuning the enclosure. It is possible to make the cabinet anysize you want and then tune it to your driver by calculating the port vent area. Try this:http://www.ajdesigner.com/speaker/i...ive you great insite into the design of cabs.

Cool site, But again. It's a theile. I really don't want to redesign a good thing. Has anyone ever heard a bad theile with an EVM12L in it. I have never heard a 1 12 cabinet sound so full. I would rather lug a combo and a cab to a gig instead of a head and a 4 12 but thats just me.

I wish I had the time to experiment with different designs, remember, what sounds good to me may sound like poop to others.

Again, thank you very much for the kind words. I was going to pull my head and build an imbuya can and then a matching theile. When I got the amp I was suprised that it looked brand new, so i am leaving it as is. Maybe I will change my mind one day and do a head and 2 cabs out of exotic wood but for now I am content. Well I hope to be, I havn't applied the tolex yet, I could really F that up.

My point is it would still be a "theile". The Theile-Small formula can be inversely applied to the size of the enclosure using the specs for your desired driver. By taking EV's info and specs and plugging them into the calculator program then entering your box dimensions it is possible to "tune" the port area to have the cab produce the same resonant frequency as the smaller EV or Boogie 1.3cf cabinet. What we're looking at here is wheather or not to consider optimum cabinet dimensions as your priority or wheather to make the most portable cabinet size (as did Boogie). Wheather you're building a cab with internal air volume of 2cf or 1.3cf it would still be "theile" when you use the Theile-Small formula to calculate the port area to your desired resonant frequency for your driver of choice.

I am certainly going to try the widebody cabinet but shorten the depth as suggested to allow the 1.3cf of volume and remove the cavity. Calculating the mass should be easy enough. I am also going to build the first one using EV's port cleat length which allows a port cap to be installed over the center port to further tune the cab without interfering with a grill cover. Only I am going to port the cab on both the left and right sides and experiment with different portings. For instance, 2 open ports on one side and only one on the other. There would be so many different options the musician could play with based on what speaker they use or what tone they are after. If the original tone works best then a full port cover could be applied to either side. However, first things first. Lets see how this one sounds.

 

[edward]

Ahhh, Widebody Thiele w/o the deadspace, same internal volume as orig formula ...glad "someone" suggested that! Cool!!! Please report back!

Suggestion: how about the port at the bottom of the cab instead of the sides?

Another suggestion: how about the baffle board at a slight angle upward ...grill could still be mounted square so as to look normal, but the speaker facing slightly up for projection (I'm thinking this may be better since more often than not these cabs are placed at the bottom of a rig. Thoughts??

Edward

 

[racer*x*]

all great thoughts! but in my case where i play this one gig that has 35 ft ceilings and the stage is 5 foot off the ground it gets tricky. you dont wanna beam people in the face but you dont wanna shoot the guitar over their heads per se either. mixing is a tricky thing. ultimately a guitarists wants to feel his rig , yet not impose on the other members of the band but sound good out front as well. thats wher FOH comes in. i used to mic the cabs then went with a di for the longest now im religous about thieles and i run two. gives me options o plenty! my latest thing is to put them both on the ground facing inward about 10 degrees each. this works for most places. sometimes i run vertical stack though and its nice too. our drummer has four kits so a lot depends on which one he brings as well.
so many variables, jeez. ive finally learned what might sound good on the stage to me might not sound great out front or in the mix. fortunately were a 3 piece have always been and im not competing with another gear head in the guitar dept.

 

[Boogafunk]

hey, restless, any vented enclosure is technically a thiele, but tuning an enclosure to a certain driver requires an air volume dictated by the driver's specs. there is a range of usable volumes for any given driver for sure, this mostly depends on the target range of frequency respose. you cannot go too far from optimum either bigger or smaller without getting huge peaks and valleys in the frequency response (or a flat shifted response, ie the respose range is too high or too low for the application) reguardless of the porting. that is why most 218 pa subs are huge. lots of airspace. if they were built in smaller enclosures, say just big enough to hold the drivers, they would have a horrible response. now they would be easier to move around and much lighter but they wouldn't be worth a ****. porting can only do so much. you have to have a usable airspace to work with. sometime soon i am going to model an evm12l and see what the respose chart actually looks like. i'll let you guys know something about how the airspace and porting will change the response.

 

[trickyrick]

Whats up guy's, I have been doing some numbers crunching and this is what I came up with. Boogafunk, a lot of this is targeted at your expertise and I will defer to your opinion. According to the EV TL806 plans for a standard size Theile which is 1.3 cubic feet, or for this excersize 2218.125 Cubic inches, I am trying to come up with the same volume for a different size cabinet. Obviously one that would fit under a widebody Mark but without the extra chamber. Whew. So I am calculating these numbers based on inside demensions only....if you were to increase the width of the cab to 21" ID which gives you the 22.5" OD for the WB, kept the height at 13" ID - 14.5" OD, you would have to decrease the cabinet depth to 8.120" ID - 10.3 OD. to get the same amount of cubic inches ( give or take a few microns :lol: .

Now the standard depth of a mark cabinet is 11.250" which is nearly a full inch wider then what the super new and improved Theile widebody cabinet would be, or as I like to call it the SNITWC. Would that inside depth be too shallow to allow the air to flow freely and to port properly?
Could you make the cabinet enclosure the full 11.250" to support the Mark but inset the back wall which would leave an exposed lip around the rear of the cabinet? I don't see a proplem with the lip around the back, I am just not sure as to the inside depth issue. :? Blast a power cord and watch the back of your cabinet fly off and blow a hole through your drummers front kick drum skin :twisted: Sorry dude, my bad.

So what do you guys think, cause my brain hurts.

 

[edward]

Hey Trickyrick,

Thanks for giving it a go and doing the math ...I certainly appreciate that!! While I will leave the technical responses to those who actually know what they're talking about, may I respond to your cab/head dimensions mis-match issue?

You can certainly make the exterior dimension larger and inset the rear panel, but how about insetting the front panel instead. I think it'd be aesthetically more pleasing if the back were flush and the grill mounted where it should be. But the baffle board can certainly be inset of the grill. Easy operation, I would think, as you could easily create a lip onto which the grill mounts, and simply place the baffle where it belongs to maintain exact interior volume.

And if you're going to try this, you can also calculate volume with the baffleboard angled slightly up, should you want to experiment with that dynamic. In fact, since we're talking about a "testbed" here, would it be possible to make the baffleboard removable or adjustable for trial purposes? That way if it sounds sucky, you still have a good cab that only needs baffle re-mounting to make it sound "right" again. Thoughts?

Edward

 

[trickyrick]

Hey Trickyrick,

Thanks for giving it a go and doing the math ...I certainly appreciate that!! While I will leave the technical responses to those who actually know what they're talking about, may I respond to your cab/head dimensions mis-match issue?

You can certainly make the exterior dimension larger and inset the rear panel, but how about insetting the front panel instead. I think it'd be aesthetically more pleasing if the back were flush and the grill mounted where it should be. But the baffle board can certainly be inset of the grill. Easy operation, I would think, as you could easily create a lip onto which the grill mounts, and simply place the baffle where it belongs to maintain exact interior volume.

And if you're going to try this, you can also calculate volume with the baffleboard angled slightly up, should you want to experiment with that dynamic. In fact, since we're talking about a "testbed" here, would it be possible to make the baffleboard removable or adjustable for trial purposes? That way if it sounds sucky, you still have a good cab that only needs baffle re-mounting to make it sound "right" again. Thoughts?

Edward

I actually like that Idea better! As far as being able to save the cab if the slanted baffle experiment fails probably wouldn't work because I would want to dado in the baffle which I wouldn't be able to do once the cab was assembled properly. Unless I just screw the cab together for testing then make bracing for the baffle angle. If it fails, I could remove the bracing disassemble the cab and use it for parts. It's a long winter here, and I intend on trying several different options in between my honeydo list.