BillFitzmaurice.info

Caveats:

1) I don't want to start a new trend whereby Bill will get hounded to make plans/recommendations for Lite series of Titans,

2) The idea of me building an experimental T39 lite has been run by Bill with other Auth Builders able to comment/advise

3) Bill said that Baltic Birch would be his ply of choice and would not do it in any other ply - he could not predict if Italian Poplar would work or not, and

4) If this doesn't work, I've just lost 3 sheets of 9mm Italian Poplar, some glue and about 26 hrs labour and I figure it's worth the gamble.

So, the T39 is 20" wide external. 9mm ( 3/8" ) Italian poplar sides, tops back and panels, 1/2" Australian Hoop Pine woofer baffle and step off, braces from 4mm ply ( the stiffest I could find o the ply store ), 3 braces per width dadoed into panels and staggered.

The ply is a bitch to work worth I must say and controlling warp is a nightmare - BUT - it's real solid construction so far and once the glue sets there's absolutely no movement in the cab.

Here are some shots before the last side goes on.





With the 3012LF drivers, I am picking that this will come in at about 18KG ( 41 kg ) or perhaps less

There will be wheels at the back 45 degree panel and that panel will have some 1/2" AHP blocks glued in to strengthen around the glue areas.

Only one handle which is the BFM style cut in at the top.

Great work Harley!

It makes me wonder,
If you're going for light the only explanation I can assume for the full length 5-8 braces and 3x 4-6 braces is because of light bracing material and panels?

And is there a critical mass in brace material when drilling out holes?

Grant Bunter wrote: If you're going for light the only explanation I can assume for the full length 5-8 braces and 3x 4-6 braces is because of light bracing material and panels?

Correct

Grant Bunter wrote:And is there a critical mass in brace material when drilling out holes?

FIIK

I just wanted to make sure that the amount of baffle material didn't do any harm to the sound waves. On the older Titans, I know you had to swiss cheese the first one or two braces.

I think potential horn panel resonance modes have probably been well tested in 12mm at various over width spacings.

Staggering the braces shifts all the resonant frequency sets around, hopefully not coinciding with the new dual panel modes.

I wouldn't hesitate to build any of our cabs from 3/8" myself, I just don't recommend it in general as it does complicate the build quite a bit.

More like building an aircraft part than building a cabinet.

Radian wrote:More like building an aircraft part than building a cabinet.

More like building a speaker the way it should be built, which not the least bit coincidentally does resemble an aircraft or boat, where high strength and light weight is a must. Commercial cabs don't do it this way as the labor cost would cut into profit margins, and they don't care if the cab is heavy when you're the one lugging it around.

Cool project!

very nice.

Bill Fitzmaurice wrote:

Radian wrote:More like building an aircraft part than building a cabinet.

More like building a speaker the way it should be built, which not the least bit coincidentally does resemble an aircraft or boat, where high strength and light weight is a must. Commercial cabs don't do it this way as the labor cost would cut into profit margins, and they don't care if the cab is heavy when you're the one lugging it around.

I doubt that, as with(especially tops) there is a big concurrence regarding putting out light-weight powerful active tops on the market... look at the JBL eon series, Peaveys new stuff, well I guess all brands have them.. I wouldn't consider any of them "pro" cabs but they still exist and have a high demand for them

But of some reason when it comes to Low end, ppl tend to think a cab will have more solid bottom if it's built from 20-22mm ply.. so in this matter people doesn't care as much of weight as with tops

I would love to see myself in the future carry one T39 in each hand tho..

What would be the biggest problem if building it all 9mm, flexing panels while playing at full power(bracing issue), screws that misses their goal when assembling or warped panels when assembling?

osse wrote:
But of some reason when it comes to Low end, ppl tend to think a cab will have more solid bottom if it's built from 20-22mm ply.

Only because manufacturers have brainwashed them into thinking that, along with more watts and bigger woofers are the key to better results. Luckily we know better.

Bill Fitzmaurice wrote:

osse wrote:
But of some reason when it comes to Low end, ppl tend to think a cab will have more solid bottom if it's built from 20-22mm ply.

Only because manufacturers have brainwashed them into thinking that, along with more watts and bigger woofers are the key to better results. Luckily we know better.

Also, people care about light weight tops because they often have to lift them onto sticks or stack them on top of subs. They care less about the weight of the subs because they lay on the floor.

Bill Fitzmaurice wrote:Only because manufacturers have brainwashed them into thinking that, along with more watts and bigger woofers are the key to better results. Luckily we know better.

Luckily for us, you know better and you decided to share what you know.

I built a T39, with 3 more in varying stages of construction using 3/8" BB. If I had to do it all over again, I'd use 1/2" arauco for panels 6 & 7, and adjust the measurements (reduce by 1/8") for the thinner ply used in panel 5 and the top, back and bottom panels.

Seems to work fine, though all I've done is run some 60Hz at about 15V through it.

I've got a new house that needs extensive cosmetic work done, or I'd be putting some time into speaker building.

Bill Fitzmaurice wrote:

Radian wrote:More like building an aircraft part than building a cabinet.

More like building a speaker the way it should be built, which not the least bit coincidentally does resemble an aircraft or boat, where high strength and light weight is a must. Commercial cabs don't do it this way as the labor cost would cut into profit margins, and they don't care if the cab is heavy when you're the one lugging it around.

Titans are just big torsion boxes with a horn path threaded through.