David - Just For Fun

[ewetho]

Well, I got to hear the David before and after finishing our new PA Sized SLA and with extra power and taking off some of the bass Steve had cranked in that tweeter is starting to hold its own but the SLA just adds some final finesse and detail the David just does not get. However THIS IS VERY MINOR and unless you have heard an SLA you might not understand whatwe are tlaking about. The David with corner loading is OUTFREAKING STANDING!!!! WOW O WOW!!!!

That thing CRUSHES!!! Heck the one sub kept up fairly well with the top of the David and the SLA 612 I finished today. This one!!!

[ewetho]

With the David and the SLA 612 going at 150W they were hitting 112 dB at 3 Meters. Ouch!!

With the sound front being so big measured volume of the SLA was less than the David but seemed even while listening.

[chaywood]

SLA plus "bass unit" ( David, Autotuba, TableTuba) = Mcintosh XRT18

Seems like you guys have re-invented the best of the best.....

CH

[saloonstudios]

Nice, I'm glad someone made these. Now I have a decent reference if I ever decide (have time) to make a pair. Thanks, they look awesome-

[ewetho]

The remaining parts for #2 is going on order tonight so soon we shall have the PAIR to tell you about!!! The bass is making us nervously excited!!!

JUST BUILD THEM!!!!

[cbarth]

How is your progress? This thread has been quiet too long!!

[Steve Regier]

I have David #2 in build. However, they will be incorporated into my home theatre so....... I am in the process of remodeling my livingroom. My 64" projection DLP system went to Ewetho. We constructed a built-in center for him so he can use his SLA's with it. Then I purchased a really good plasma unit to go on the wall. Now I'll touching up the equipment rack to hold the electronics. Then I will finish David #2 and install.
pics to follow

[ewetho]

Here is the offending David/PLA 612s/etc etc etc show stopper!!!

One built in for a 64" DLP rear projection TV and 3 SLAs and Stuff.

Finish work to Come. Only holdup is we went with a Tuba 24" for now on the sub as the T36 would not fit and due to the line level difference that the old Ashly want versus my Sherwood it also need a Power DI (no problem will have shortly).

[BassMe]

Hey Guys,

First of all Baron + Ewetho, thanks so much for all of your great threads detailing the builds, experiments and reviews of the BFM stuff. It has helped me a great deal giving me idea's of what is possible etc. These David's look positively smicko btw. Baron do you have a HPF running on the low end to safeguard the driver from being shredded? The cab is essentially a AT so should be HP @ 40Hz if your playing it 110+ dB? Just wondering...

I have been watching the thread closely and have been considering the SLA or TLAH / AT combo that some people have mentioned here. I was thinking 2x 9 driver rectangulat TLAH mounted on 2x 10" driver TAT's or AT's should give me an 8 ohm load too making them easy to drive with home audio gear. I ain't got the money to buy anything in the next month or two (looking for a new job is very frustrating) so all I have is time to plan and think and scheme lol.

I am looking into this, but need some guidance to where I can get relevant info about designing a cross over so these can be used as L/R mains not as a 2.2 setup. I'm fairly certain a setup like this would absolutely rock and it'd be an interesting experience. I already have SLA/TLAH/AutoTuba/TT plans so all I need to work out is a 3 way cross over. Might run miniDSP -> 2 channel amp -> stereo setup, so that I'd have some nice EQ options. I could do the AT to TLAH cross over in miniDSP but I'd need 4 channels of amp which I don't have, though it could be a possibility if there is no easier way. I'd prefer to two 3-ways though.

Anyone know a good cross over design for dumb***'s resource? I definitely don't want to pester someone with this seeing as it's experiment and learning is good for me.

Thanks.

[Steve Regier]

I have shredded many MCMs and would use a HPF if using a MCM. I now use Tang Band W8 740s and just let 'em pound. I have yet to smoke one and I run them hard!

[BassMe]

Sounds like fun. Any experience with the Dayton DCS255-4? For the extra $4 and a few more inches of size the 10" looks like a good option if it is built well like the tang band. Can pound some more then

After some further investigation biamp with an electronic cross over actually does seem cheaper than buying the caps for a 100 Hz cross over lol. Rather disappointing really. The lalena cross over site 3-way designer tries to cross the sub at 500Hz which is not something I wanna do... Hmmm. Further investigation required.

[Steve Regier]

Bigger is not always better. The TB W8 740 outperforms quite a few 10s. I don't have any experience with that Dayton model. I would check with Bill before substituting a driver. Substituting a larger driver might actually hurt performance. But experimentation can be fun.

[BassMe]

the 10" is actually recommended in the AT plans. 19" wide with 10" driver x2

The Dayton 10" has:

Vd: 287.5 liters
Xmax: 8.3mm
SPL: 89db 2.83v/1m

Tang:

Vd: 220
Xmax: 12mm
SPL: 84dB (PE lists 2.83V/1m but Tang band data sheet shows 1w/1m which would make it 87dB 2.83V/1m due to 4ohm impedance)

In the plans for the TT Bill lists the 10" as an option for higher output then the 8" options. While it has less Xmax and therefore can reach Xlim and shredding faster it's higher sensitivity + large overall displacement seems to be a counteracting force? Bill has also stated that higher sensitivity is usually more desirable than displacement in a horn sub as you can reach higher volume with less displacement anyway therefore reducing risk of shredding and distortion simultaneously. (Though how something is more sensitive while having less displacement works is beyond me??)

I think I got this right, I only really know what I read. But the Tang-Band seems like a solid option really and I imagine they are fairly comparable. The other day I thought I had found some HL-10C in stock here is Aus, but alas the company was just slack and hadn't removed the listing. Was a let down.

I'd like to build these as 2 full range towers, but $200+ in cross over components seems fairly hectic and that's if I get the cross over right on the first go. Those 200mF caps are not cheap!

Thanks baron and ewetho for your replies How goes the building on the 2nd one?

[Steve Regier]

I think you are correct in general theory here. I was referring more to personal experience. I have shredded many drivers but the TB takes all the abuse I have dished out and they are still playing.

[BassMe]

Well I am thinking of going the TB's now, just cause everyone seems to think a fair bit of them and according to Bill there isn't much of a diff due to horn loading. And I imagine after the abuse they have suffered they must be fairly sturdy Thanks Baron for the info. Rather go with what is tried and true.

How wide is the AT in the David? Just wondering for comparison sake, as I'd probably build the 18" TAT. 2 TAT with cabin gain, corner loading + V Plate would be able to rock fairly hard and when I have a bigger house I can swap em into TT's. If I understand cabin gain correctly; the longest dimension in my listening room is 19.43 feet, which is approx 55Hz wavelength. So at 27.5Hz I should have a 12dB gain. Corner Loading will give me 12dB, 2 drivers will give me 3dB and V plate will give me 2.5dB. Should be alright in a 257 sq/ft room.

Can't wait to hear your reports on having both built