BillFitzmaurice.info

djtrumptight wrote:I see a mistake,i dont know how crucial it is but your vertical braces shouldn't be to the edge on a wide cab,the horizontal braces should have been installed centered then the vertical braces butted to the horizontal braces.

t 39 mistake.jpg

I know what you mean and this is the way I decided I would do the vertical braces:




So I wind up with 2 sets of vertical braces, I felt it gave a better base and seal to the chamber instead of just the one near the center, and just using edge joining on the outer edge.
I also found that cutting an extra 1/4" out of the panel extension gave better access to the 12" driver bolts. On my successive builds I will reduce the width of the extension by this 1/4" from 1' wide to 3/4" wide instead of having to cut some out. It also makes it unnecessary to only screw without gluing the access flange onto the extension incase the 12" driver won't fit with it installed
Plans quote:
With a twelve trial fit the driver and upper flange
to be sure it will go past the upper flange. If it doesn’t leave it off for now, install it
after the driver is installed, using screws only, sealing its joints with the cab and the
vertical braces with driver gasket tape.

figured I could bypass the whole sealing up at least this one joint with gasket tape.

Grant Bunter wrote:

heavybdrums wrote:Driver has been broken in and mounted now its working and sounds freakin' awesome. I'm currently just driving this Titan 39 with a 500 watt ( 30 volts max) amp for leak testing..and passed w/ flying colors, but I had no doubt.

Looking good!

Ummm is that 500W max into 8 ohms?

If so, please recalculate. I get 63V with:
http://www.rapidtables.com/calc/electri ... ulator.htm

Using the same thing, even if that's a 4 ohm output, it's still 42V.
Neither of those figures account for amplifier transients.

Make sure you are feeding the amp via a driverack etc, just to be sure.
I hate to see you blow a driver at this or any stage...

yes but for the leak test I limited at 30 volts and figured this would be enough for the leak test. For regular use it will be limited @ 50 volts on this amp.

For leak testing, 10V@20-25Hz is plenty. Use a length of tubing or a mechanic's stethoscope to locate any leaks.

for the leak test I limited at 30 volts and figured this would be enough for the leak test

From the plans: Run a 25 to 30 Hz test tone at 10 to 12 volts.
As is always the case there's a reason for this instruction, which appears just below the first: The test tone will be very hard to hear, but the noise of air rushing through leaks will be easy to hear
If you run a higher frequency tone the tone will dominate and it will be hard to hear a leak. If you run a 25Hz tone at 30v you run the risk of over-excursion.

So this happened: I got a chance to supply racks and stacks (amps and speakers) to a national touring band on Tues (9/22/15) called Tauk in a local bar in Blacksburg. This was also my first use of my new Titan 39:


I had just finished building it on Sunday, but had not finished sanding and painting so I covered it up with a table cloth



And of course my Wedgehorn 10's were in use also:


And the place was friggin' PACKED: ( fog machine made it look smoky with the flash)



They brought their own lighting rig, which the tech did a very nice job of:



Nice Yamaha drum kit:



big keys set up:



I mean, these guys had lots of expensive gear running this show. The gig was awesome fun, the band was great (heavy rock instrumental), and even though the stage manager gave pause when I told him what I was bringing, he wound up being very happy. One Titan 39 was just enough for this size room but 2 would have been even better. (and replacing the Peavey Sp 5Ti mains with Dr 250's of course). Another T39 on the way very soon.

(EDIT): I had great fun telling the mob surrounding the sub (what will we call them? you know those people who strategically place themselves at the subs) that I built it myself, they were very impressed with the table cloth and air movement.

heavybdrums wrote:what will we call them? you know those people who strategically place themselves at the subs

They are called "BASS-HEADS"!

Nice review, and very glad things went well. Horn loaded subs work best in herds. Adding a second one will add +6dB, adding another pair will add another +6db.

Having the sub up front and centered like that really robbed you of performance. You also did yourself no favor by putting the W10s so close together. I am guessing the "lead" singer stood in front of them. Can't teach old dogs new tricks....

DJPhatman wrote:

heavybdrums wrote:what will we call them? you know those people who strategically place themselves at the subs

They are called "BASS-HEADS"!

Nice review, and very glad things went well. Horn loaded subs work best in herds. Adding a second one will add +6dB, adding another pair will add another +6db.

Having the sub up front and centered like that really robbed you of performance. You also did yourself no favor by putting the W10s so close together. I am guessing the "lead" singer stood in front of them. Can't teach old dogs new tricks....

The band's stage manager and sound guy placed things where they wanted them, the w 10's are for the bass player and guitarist to get keys, there were no vocals in this band.

DJPhatman wrote:

heavybdrums wrote:what will we call them? you know those people who strategically place themselves at the subs

They are called "BASS-HEADS"!

Nice review, and very glad things went well. Horn loaded subs work best in herds. Adding a second one will add +6dB, adding another pair will add another +6db.

Having the sub up front and centered like that really robbed you of performance. You also did yourself no favor by putting the W10s so close together. I am guessing the "lead" singer stood in front of them. Can't teach old dogs new tricks....

Certainly do intend to make more T39's but it was all I had atm, and I wasn't going to turn this opportunity down. The room has many limitations on placement of subs, and as you can see the stage is small, just big enough for a 4 piece band. Fear not the sub content was adequate for this small room, and I will have other occasions where I will be in charge of where things go, but for this gig I was only supplying gear as a rental. This is something that seems odd to me, so help me understand: adding a whole nother cab and another amp channel will only add 6 db? I'm sure you know better than I, but I sure hope that adding another 400watts and another cab adds more than 6 db?

heavybdrums wrote: I sure hope that adding another 400watts and another cab adds more than 6 db?

There's some learnin' comin' yo' way......

http://www.sengpielaudio.com/calculator-levelchange.htm

heavybdrums wrote:

DJPhatman wrote:This is something that seems odd to me, so help me understand: adding a whole nother cab and another amp channel will only add 6 db? I'm sure you know better than I, but I sure hope that adding another 400watts and another cab adds more than 6 db?

It adds +6dB due to an extra radiating cone (in other words, a driver), and you've doubled the power (because you feed the same power to eg, 2 cabs instead of one).

In order to understand 6dB as an increase in volume, +3dB is often described as "noticeably louder", while +10dB is "twice as loud".
+6dB is somewhere between those.

As a sidenote, I'm working as a tour guide at an aviation museum at present.
One of the things I've learnt is that the addition of some perforated sheets on the inside of the jet engines (for 747-200's), just behind the cowling, has lead to a reduction in noise from those engines by 11dB.
That means, as a minimum, that perforated sheeting makes the jets at least half as loud as those engines without the perforated sheets...

heavybdrums wrote: I'm sure you know better than I, but I sure hope that adding another 400watts and another cab adds more than 6 db?

That's why the sensitivity of that first cab is so important! Diminishing returns happen quickly in subwoofer land. Adding another cab only adds 6 dB's when you go from 1 cab to 2 cabs. After that you have to double the cab count to get another 6 db's, that means 4 cabs for the next step up! After that you have to go to 8 cabs to get another 6 dB's, then 16, then 32!

However dire that seems, there is a way to get some free dB's. With 2 cabs you can build the V-plate to add 2-3 more dB's for free. That's like running 3 cabs without the V-plate.

Also, read the placement sticky. If you put that cab of yours against a wall for that gig, you would get +6 dB's, same as running 2 cabs. If you put it in a corner, you would of got +12 dB's, same as running 4 cabs out in the open!

Keep in mind that the Bell is a logarithmic unit.

Thanks for all you guy's input on this. My take-away from this info is that +6 db is more than I had previously thought, with the added effect of coupling and V-plating, and the possible corner loading (I will have to be creative to achieve this, still thinking how I can do that in this room).

The issue with corner loading here is that the only corner available is 25' to the left of stage center, and 12' behind stage front. I will definitely try this, with appropriate delay between tops and subs, but I am initially dubious that this would be the best thing for air movement at the center front of stage. Percussive air movement at this position is the goal, since that would correlate physically with where the kick drum is.

Painting of the Titan 39 beginning:

unfortunately Speakerhardware is out of Duratex and has been for some while so I had to order direct from Acry-tech, and a price increase has come to $70 instead of $57 with shipping and handling.

Sorry, a day late. Back in stock today.