Light weight cabinet build

[41hzthunder]

IIRC, the E-140 should have greater Xmax than the K-140.

With aftermarket recone kits, EVERYTHING is a crapshoot.

The T/S parameter sheet JBL published in 2008 says E-140 is 3.56mm and K-140 is 5.08mm. I keep thinking its a typo, but that's what it has. The current cost of reconing these drivers is close to or exceeds the cost of modern drivers with similar or better parameters. I don't know if I would go there anymore. I'd more willingly pay a few more dollars, have something delivered, and be in spec. I just happen to have this driver and the plywood. They need to do something for me or go away. A hard statement for a K-140 fan.

 

[41hzthunder]

I was using DATS V2 back then, I have the V3 now. Great piece to have if you're into building speakers and such.

I'm pretty sure Agedhorse is right. The E series was the next step, besting the K in xmax and power handling. Your situation is hard to predict.

I'm contemplating buying the DATS V3. So your input is helpful. If I could get T/S parameters on this driver, modeling would be better and I have other cabinets/drivers I'd like to test.

 

[41hzthunder]

This is a lightweight 1x15 i built for myself. Top, bottom and back are 6mm plywood, but with the mesh bracing, also 6mm plywood, end on. The top and bottom work fine, but the back, which was intended to be removeable, resonated excessively and I had to upgrade it heavily (in both senses). The baffle is a sandwich of ply with a fibreboard core, end grain balsa would be better.

There were two big lessons I learned. The first is that a removable back was a mistake, its better to accept the inconvenience of having to remove the driver and have the bracing integrated into the corners and edges.

The second lesson, which builds on the first , is that cross bracing and diagonal cross bracing are enormously weight efficient, and very much something to incorporate. Idid soon a subsequent 1x10.

All this complexity is of course hopelessly time consuming and expensive outside home building. The cab is under 30lbs, but I reckon if I did another with those lessons I could be around 25.
View attachment 7393629

Wow! 6mm panels!!! That's pretty interesting. With panels that thin, you have to have corner bracing. Does this box resonate a lot. I once made a router table with 1/4" ply and 1X4 bracing on edge, very similar to your bracing pattern. I did it to get a flat surface that wouldn't change with the weather, and it was flat. However, it amplified the router so much it had to go. By diagonal bracing, do you mean middle of the side to middle of the back and so on? I've been pondering that.

 

[41hzthunder]

To move forward, I’ve made the assumption that I can get the parts to work at the weight I want. That may or may not be true, but I need to workout the size of box to know how much plywood will actually be used. I don’t have the actual T/S parameters of this driver, but entered E-140 specs as recommended on the Lansing Heritage site. SPL, Cone Excursion, and Air Velocity are my concerns at this point. To start, I’m looking at three box sizes: 3.2 cubic feet, 3.75, and 4.2. I’m setting the box tuning for each to 40 hz, 49 hz, and 55 hz. These are not my final options, I just want general information on how box size and tuning model. If the fundamental is masked by a louder 1st harmonic, there’s a good argument that a bigger box tuned lower is not the best solution. Here’s my results.

3.2, 3.75, and 4.2 cubic foot box WinISD

 

[agedhorse]

The T/S parameter sheet JBL published in 2008 says E-140 is 3.56mm and K-140 is 5.08mm. I keep thinking its a typo, but that's what it has. The current cost of reconing these drivers is close to or exceeds the cost of modern drivers with similar or better parameters. I don't know if I would go there anymore. I'd more willingly pay a few more dollars, have something delivered, and be in spec. I just happen to have this driver and the plywood. They need to do something for me or go away. A hard statement for a K-140 fan.

My memory suggests that this is in fact backwards, or that the E and K are 3.56mm, but something in the back of my mind recalls the E-140 being a little longer VC winding height.

There is another possibility, and that is a difference in the top plate thickness, which if thicker on the E-140 would subtract from the Xmax when the winding height is the same. I can't find my recone data binder, but I think this data was in there. I kind of remember that the winding heights were the same, about 7/16-1/2".

It's been a very long time since I reconed any of these. When the supply of genuine parts dried up and the (good) aftermarket parts that were the replacement dried up, it wasn't worth the grief of messing with what was left.

 

[agedhorse]

6mm plywood thickness at the edges won't hold up on the road, way too thin.

 

[41hzthunder]

My memory suggests that this is in fact backwards, or that the E and K are 3.56mm, but something in the back of my mind recalls the E-140 being a little longer VC winding height.

There is another possibility, and that is a difference in the top plate thickness, which if thicker on the E-140 would subtract from the Xmax when the winding height is the same. I can't find my recone data binder, but I think this data was in there. I kind of remember that the winding heights were the same, about 7/16-1/2".

It's been a very long time since I reconed any of these. When the supply of genuine parts dried up and the (good) aftermarket parts that were the replacement dried up, it wasn't worth the grief of messing with what was left.

Definitely would be interesting to know. For myself, it probably won't be an issue. I don't have or plan to run the wattage to push the driver. If it is a difference caused by the plate, then I would have the larger Xmax from the K-140 frame. Still, I'd have the less powerful motor. Dang!

 

[41hzthunder]

So, a bit of fun yesterday. I tried to weigh myself holding the 4 X 8 sheet while on a scale. Sometimes, the really dumb ideas only become obvious when you try them. I couldn't hold the board and read the scale. What numbers I could see just moved around. I did laugh at myself and am glad my wife didn't see that!

I also played around with an EQ on some bass recordings in my favorite DAW. I tried different headphones and speakers while moving the roll-off point between 40 and 55 hz. Between 40 and 50 hz there really wasn't a noticeable change in the low end. What I could hear might have just been ear fatigue. And, I really wanted to hear something. However, I did notice increasing the roll-off point seemed to tighten up the tone and it got deeper,. A subjective description, I know. It could have been ear fatigue, but I was definitely not expecting that.

 

[JimChjones]

6mm plywood thickness at the edges won't hold up on the road, way too thin.

The joints are backed with cedar battens. Roadworthiness comes in degrees, doesn't it! I don't have to baby it too much, but only I handle it, and I doubt it would stand up to a pro road crew every night on a 50 date tour! I would be more worried about the corner of something penetrating a panel, it would be a b****r to fix. More to the point, perhaps, anything that goes wrong is down to me, I don't have to worry about warranty claims from the dear public.

Does this box resonate a lot.

The back you can see in the photos certainly did. But the rest I'm happy with. I gave it a bit of a thrashing when I first built it to check that out, but my actual live band has no drummer and no electric guitars, so its not the most arduous of gigs.

By diagonal bracing, do you mean middle of the side to middle of the back and so on? I've been pondering that.

Yes indeed. Right across would be good too. I forget whose build inspired me to do it (I've used it on a 1x10) but once you think about it the cab sides must all pulse in and out in sync with pressure changes, so joining opposites must make the panels stiffen each other up. Need to think very hard about construction though, the joints must take a hell of a beating. I'm sure mechanical fasteners would loosen up in pretty short order.

 

[6thplanet]

The T/S parameter sheet JBL published in 2008 says E-140 is 3.56mm and K-140 is 5.08mm. I keep thinking its a typo, but that's what it has. The current cost of reconing these drivers is close to or exceeds the cost of modern drivers with similar or better parameters. I don't know if I would go there anymore. I'd more willingly pay a few more dollars, have something delivered, and be in spec. I just happen to have this driver and the plywood. They need to do something for me or go away. A hard statement for a K-140 fan.

I think I read that the 5mm xmax for the K was a misprint, it's actually 2.5mm.

 

[agedhorse]

I think I read that the 5mm xmax for the K was a misprint, it's actually 2.5mm.

Certainly possible.

 

[41hzthunder]

I suppose I should have posted this so we can all see what I'm looking at. I've been poking around the Lansing Heritage site for more information on the E and K models. Most of the technical spec information comes up when someone wants to swap cones, like 2235 into an E-140 basket. Then you get some discussion of the plate thickness, coil overhang and suspension properties. Much of the discussion is prefaced by "I think", although there are some JBL technical bulletins included. Seems JBL did not publicly circulate the details. Authorized repair centers may have gotten more information. I don't know.

 

[agedhorse]

The problem is that mistakes get perpetuated to the point that they become impossible to identify.

Also, there are different ways to define Xmax, so if the method changes, so can the numbers.

 

[41hzthunder]

The K-140 and E-140 were from a time before T/S parameters. Even if I measured this driver with DATS or other equipment, some parameters would still be unverified. I'm going to have to move forward with what I've got and watch the Xmax when modeling the excursion. WinISD is going to be a starting point that is in the ballpark. Its hard to imagine the driver can't handle a clean 150 watts or less.

I'll work on cone excursion models later today.

 

[agedhorse]

WinISD is riddled with quirks, it's not uncommon to get questionable results. BassBox Pro is a much better platform IMO.

 

[41hzthunder]

WinISD is riddled with quirks, it's not uncommon to get questionable results. BassBox Pro is a much better platform IMO.

Yup. The first thing I noticed was some drivers in its database not loading and passing consistency checks. I don't know if it was the driver T/S parameters or the software, but it was data that came with the download. I'm aware of a couple other potential issues in WinISD, so I'll see how it goes. BassBox used to have a lite version. I don't think they support that anymore. I think Eminence sold a version of it too.

 

[agedhorse]

That's just a taste...

 

[Deloofs]

I recently built a fEARful cabinet using bracing. I added mortise and tenon elements to the design to locate and secure the bracing. It worked very well but you have to get the fit right. I used CAD software to design it and a water jet to cut my plywood. It would be a challenge to cut these pieces without a water jet or laser.

Rabbits/dados/biscuits are a good idea. Box joints where the panels meet is also a good idea.

Here is my build log:

D

Thread 'fEARful 151566 Build Log'

Jul 10, 2025

Welcome to my 151566 build log! A few months ago I posted on TalkBass asking for help with some bass volume problems with my metal band and the community here recommended the fEARful 151566. I'm handy with fabrication and I love a custom project so I decided to take it on. Please find below a log of my build!

Background and Research
I started by researching the design and past build discussions. I read all about the speakers, frequency response, power handling, crossovers, materials, glue, bracing etc. It seems that there used to be a Greenboy forum at some point which was loaded...

• Deloofs
• 151566 cabinet diy fearful fearless greenboy
• Replies: 95
• Forum: Amps and Cabs [BG]

• 
• 

 

[agedhorse]

There are a lot of alternate joining methods, some are really cool and only practical using advanced machining methods like milling, laser, fixturing, etc.

 

[41hzthunder]

I recently built a fEARful cabinet using bracing. I added mortise and tenon elements to the design to locate and secure the bracing. It worked very well but you have to get the fit right. I used CAD software to design it and a water jet to cut my plywood. It would be a challenge to cut these pieces without a water jet or laser.

Rabbits/dados/biscuits are a good idea. Box joints where the panels meet is also a good idea.

Here is my build log:

D

Thread 'fEARful 151566 Build Log'

Jul 10, 2025

Welcome to my 151566 build log! A few months ago I posted on TalkBass asking for help with some bass volume problems with my metal band and the community here recommended the fEARful 151566. I'm handy with fabrication and I love a custom project so I decided to take it on. Please find below a log of my build!

Background and Research
I started by researching the design and past build discussions. I read all about the speakers, frequency response, power handling, crossovers, materials, glue, bracing etc. It seems that there used to be a Greenboy forum at some point which was loaded...

• Deloofs
• 151566 cabinet diy fearful fearless greenboy
• Replies: 95
• Forum: Amps and Cabs [BG]

• 
• 

Really interesting thread. I gave it a quick read and will probably give it a second read tonight. Was this 12mm birch plywood? I missed the material spec in my reading. I actually have some fEARful plans downloaded from several years back. As I recall Greenboy was very specific and adamant about the drivers. I did notice you used Alphalites with concern for a 4K resonance in the recommended 6" drivers.

Waterjet! Pretty cool, but the edges did look frayed. I am working on a CNC router, but won't have it for this project. My CO2 laser isn't powerful or big enough for my project, except for any templates I might need.

I'm curious about the weight of the cabinet.

Great build!