LE14A Project: Enclosure Design

[bedrock602]

I sat down at the puter today and got started on my LE14A project. My goal is to improve upon the S99 using the LE14A's in a 3-way system. I had originally thought that I would modify the existing enclosures but have since settled on building new cabinets, saving the old ones for sake of comparison between original and modified.

The new enclosures will have the same intenal volume as the original S99 taking into account the added midrange/enclosure and additional bracing so the external dimensions will be slightly larger. The front baffle will be in two sections, woofer section and mid tweeter section. The woofer baffle will be permanently glued in place, the mid/tweeter baffle will be removable allowing me to experiment with other drivers.

To make room for the additional midrange driver, I reshaped the port into a rectangle and placed it at the bottom so that sides and bottom of the cabinet form the sides and bottom of the port, simplifying its construction.

This is just the first step. Any comments or suggestions are welcome.

[Ed Kreamer]

Hi Bedrock from Hood Canal'

I'm curious as to why (since this is a new construction) you didn't make the box a little taller and put the HF and MF on the same vertical plane instead of horizontal? I always did wonder why JBL didn't make a larger sized "bookshelf" with the le14 rather than a 12. Maybe they did and I just didn't know it.

Have fun
Ed

[Mr. Widget]

I’m with Ed on this.

Aesthetics aside, if you can get the tweeter up to standard seated ear height, or about 39” above the floor, you will usually find that as an improvement. Also, all things being equal, vertically stacking the mids and tweeters is typically preferred to help control off axis response.


Widget

[Robh3606]

This is what I would be building mirror imaged though L240ti Silly starting with a clean slate to not just go for it.


http://www.lansingheritage.org/image...-ti/page07.jpg


Rob

[bedrock602]

My original plan was to modify the S99 baffles to accept a tweeter and mid, so I simply used the original size and shape for the new enclosures, but this is just a starting point. I'll layout a cabinet with tweeter and mid oriented in a vertical plane. I'm curious, why do speakers like the 240Ti have the tweeters and mids offset from the woofers?

[Don C]

There is a small response anomaly caused by the diffraction or reflection from sound traveling across the front of the baffle and meeting the edge. The frequency of this anomaly depends on the distance from the driver to the edge of the baffle. By offsetting the driver to one side, you get two small anomalies at different frequencies instead of a larger one that is the sum of two due to the equal distance. In my experience it's difficult to hear this kind of thing. You would also want to avoid a lip or step or thick grille frame on the front of the speaker. These were common on older speakers, less common on more modern designs.

[RMC]

Hi bedrock,

For example, below is a pic of the driver response modeled in Winspeakerz with 3.8 cu.ft. tuned at 35 hz, and the usual QL 7 and half-space loading. Reasonably flat being within less than one db. So you should get something comparable to this with using same box parameters (Vb, Fb, QL).

Win ISD bugs when different versions were installed on my computer (pro 2016, pro 2002 and the smaller Beta). Had to uninstall pro 2002 and Beta to restore peace... Kept pro 2016 and Winspeakerz, the latter not free but not expensive, paid $40. few years ago and it has a 1,500+ driver database (including LE14A/H) to which I add as need be. Also has crossover design and cabinet design features, plus many easy to edit parameters. No hassles, no bugs. Fast and easy to work with, that's why I use it much more than Win ISD.

I've tried many free or low cost softwares over the years and Winspeakerz from True Audio is the best price/features/performance wise in my view. For the few who may think Winspeakerz isn't that good, well they sure have not read Linearteam's own! 20 page Technical Paper comparing eleven (yes 11) different speaker design softwares on the most criticized aspect of box design (Lv accuracy ). That comparison includes known names such as Win ISD, JBL Speakershop, Winspeakerz, Bass Box Pro v.6, etc. The results would be eye opening for "the blinds leading the blinds".

In the past Rick Carlson's free Box Plot 3.0 was among the favorites of mine up to Windows XP with 32 bits architecture, but I was never able to make it work on Windows 7 Pro 64 bits architecture, even using the compatibility mode in Win 7 Pro. As far as I know, Carlson never updated his software for more recent windows versions.

There's a sequence to follow when entering driver data in previous 2002 ISD pro version otherwise it bugs. Let me know if you need that sequence, I think I still have a copy of it. That bug was corrected in the 2016 edition, but that edition has very poor number of drivers in database.

Many people don't know ISD Pro's (2002 & 2016) has default QL10 which isn't standard, it can be changed to standard QL7 when in "box" tab then go to "advanced" at bottom of screen and replace QL 10 to QL 7. This software will always default back to QL10 with a new project, except when reopening a previously saved project with QL7, so you must not forget to change it back to QL7 again and again... Winspeakerz has the default standard QL7 which is very easy to change at will, plus or minus. Regards,

Richard

P.S. Just checked and Winspeakerz still goes for $39.95. For such small amount of money I stopped screwing around with Win ISD free versions a while ago, except for when I want to double check on something, like Lv, to get a "second opinion"...

[Ed Kreamer]

Hi Bedrock,

I think that you have improved your design considerably, but I agree with Speaker Dave regarding the larger box. If you note his examples of later use of the LE14, they are all 3+ft3. I wonder if the better bass you are hearing is the knee
of the response curve of the driver in an incorrect box. Of the examples he gave I think the 240ti ( perhaps reconfigured ) might be the best for your needs. You could make it taller and deeper than the box than the 99 box. BTW, what kind of music do you listen too?

Ed