Originally Posted by thylantyr
I wonder if John has plans to continue offering Lambda TD series woofers with
faraday motor? It's my favorite wideband woofer design for special applications
where you want the woofer to operate at a much higher frequency range while
keeping very high SQ. A typically design for this would be a 3-way home
loudspeaker; tweeter, pure midrange and woofer. It's hard to beat the sound of
the Lambda TD, I can only think of maybe a couple of woofers that can do this
job, but they are very expensive, way outside the normal DIY'ers price range.
I have quite a few things in the works. I guess I can give a little rundown. Hopefully it won't get me banned from the forum. Moderators, if there is any issue with me posting this info, I can understand. Many in this thread have been in contact with me before, so this is an easy way for me to reach everyone. That said....
The info on the website now is somewhat outdated. As things have been delayed, I have decided to do some upgrades too. The top line (for now anyway) will be the AV series now with a 2.5" coil instead of 2" coil, still 23mm Xmax. While the 2" coils would handle 1000W all day long in a car audio application, the opportunity arose to use the motor with 2.5" coil for an OEM product and ours as well, with a few modifications. These will have dual shorting rings, a full copper sleeve on the pole and a large aluminum sleeve on the inside of the magnets. This greatly reduces inductance and distortion. The biggest benefit in car audio applications though is in increasing the long term thermal constant. The aluminum and copper pull heat away from the coil and until they really heat up, the coil remains cool. In a typical woofer with 200grams of copper on the coil, it would take a certain amount of power for a given time to heat up to a failure point of around 600degrees. (for comparison, most coils fail about 375 due to the adhesives used). Now add in another 200grams of copper over the pole on the ID of the coil, then add in 500 grams of aluminum on the OD of the coil. That heat is now wicked away from the coil and disbursed among the coil and shorting rings. This means the overall temperature of the coil is much lower with a given input, meaning much higher input power before a given temperature is reached. I will release power test results and even show how we come up with the results in the near future. If a driver is rated at 1500W, it will be able to take pink noise 20-200hz with 6dB crest factor for a period of hours at that level without failure, not minutes or seconds as many drivers are rated.
For the extreme SQ applications, drivers like the TD Apollo's will be offered, but we need to rename them. These will have the 3 shorting rings including the massive 6" diameter x 1/2" thick ring above the gap plate. Now you're talking several pounds of aluminum to wick away heat! Power compression and distortion on the TD15M will be the lowest you will ever find. The TD15M is flat on axis to over 4KHz and at 30degrees off axis to over 2KHz. Yes, this has nothing to do with car audio, but a 15" woofer that can play a 4KHz tone as good or better than nearly any 5" midrange on the market has no problems playing lower frequencies accurately either.
The first key is getting rid of inductance, allowing the driver to be electrically flat to higher frequencies. The second is getting rid of resonances and breakup modes. The first and biggest resonance in a woofer comes from the dustcap, or the chamber under the dustcap. Using a phase plug eliminates that. The surround will have it's own resonance/breakup as will the cone. Proper selection of cone/surround materials and damping materials also eliminate those problems. Then combine that with the low inductance motor design and you have a driver that can play accurately over a very large bandwidth.
The designs have only been improved upon from the Lambda days. I will be using a TD15H in my own show vehicle along with a pair of 15" PR
's. The rest of the system uses Scan Speak tweeters and Seas Excel mids with a dBx Driverack260 for the system processing.
Efficiency is also the key with the TD15M in the range of 99dB 1W. Yes, it is not practical for everyday use in a vehicle due to lower excursion capability, but in the right enclosure it can get very loud. SPL woofers do not need high excursion if the enclosure is done right, they only need to excite the resonance of the port. The port does the work, not the driver. A single TD15M in a properly designed vented enclosure can close in on the 160dB range with only about 250W input power. In a few months I'll be doing a tutorial on how to do just that and hopefully can post it here.
I also have some lower cost options that will be available. As I have said, the info on the website is a little out of date. The intro 12's will be a little more expensive than originally planned but have been upgraded to 16mm Xmax, a slightly larger motor, and a little more power handling. Y
EVERY woofer that comes off the line will be tested at the QC station prior to packaging, given a serial number, and actual measured parameters will be included with each driver. We will also have an option to paint frames and/or steel can be custom painted to any standard color code to match your vehicle.
So that's some of the stuff that will be going on soon. Until then, you probably won't be hearing too much from me for a little while. I need to go back into hiding to prepare things that are coming in the next few months. Expect to start hearing news towards the middle of may. There won't be any preorders as there were in the past. No money will be taken until I have drivers in hand and ready to go out the door. When we have drivers we will most definitely make it known.