BillFitzmaurice.info

Bill Fitzmaurice wrote:Read it again, then consider that you can't hear +,-2dB deviations.
One thing that drives me nuts with oddiophiles is that half the time they worry themselves half to death over anything that they can see on a chart, whether it's audible or not, while the other half they claim to magically hear stuff that can't be measured at all.

Exaxtly the kind of answer I was looking for. Thank you.

BassMe wrote:Hey,

Check the impedance charts carefully for those tweeters. At about the cross over range the impedance is actually very low, down around 4-5 ohm. In that thread I linked there is two links to zaph audio where he has done his own impedance chart measurements, which when you look closely actually reflect the SB charts as well. i dont know where they get off calling them 8 ohm realistically.

And its no problem, I have been looking for a guinea pig for them for a while

Good info Mitch. Fortunately I ordered a few extras so I could have the option of running 4 banks of 5 tweeters for a slightly higher impedance if needed. In the plans Bill mentions an acceptable range of impedance ratio between woofer and tweeter. I should be right in the acceptable range.

I make a pretty good guinea pig...there will be plenty of mistakes to learn from in the end.

All I can say is these TLAH Pro are going to be beasts!

Have you chosen your cross over point yet? I was looking to cross at about 3000Hz or maybe even a tad lower at about 2600Hz.

Glad to be of help, least it reconfirms my own thinking

Have fun!

BassMe wrote:Have you chosen your cross over point yet? I was looking to cross at about 3000Hz or maybe even a tad lower at about 2600Hz.

I was thinking of sticking with 3500Hz. I'd like to go lower if possible, but I wouldn't want to limit my max output by crossing over too low. I think SB mentions their recommended range is 3k - 20k.

They came in today from Madisound, here's a pic (sorry for the crappy cell phone quality):


Reading plans, it mentions that when using more of fewer tweeters than 8, to stick with 2 parallel banks. Maybe I'm doing my math wrong, but with 16+ tweeters, that puts my tweeter line's impedance at just over 1 ohm. Am I still okay with going with 4 banks of 5 tweeters, or 3 banks of 6 tweeters, parallel wiring the tweeters in each bank, then series wiring the banks together? If I do it this way, I come out much closer to 4 ohms I believe. Just trying to understand the reasoning of sticking with two parallel banks.

GirlyHandedDog wrote:Just trying to understand the reasoning of sticking with two parallel banks.

Simplified wiring. If you have so many tweeters that you need to run more than two banks by all means do so.

They look far less truncated then I thought they would lol. Are you planning to rear or front mount?

I would say SB recommends 3k as the lowest point cause people commonly use 1st and 2nd order crossovers. Using a 3rd order, I reckon you'd be fairly good to go down to 3k.

BassMe wrote:They look far less truncated then I thought they would lol. Are you planning to rear or front mount?

I'll be doing a front mount. It will almost be like the multi-element single mouth horn in the plans when using the piezos, since I won't be separating them with any vertical spacing, and the tweeters are already pre-cut/truncated. As far as the amount of truncation, it could be an optical illusion based on the camera angle in the previous picture. Here's a couple of straight-on shots:

BassMe wrote:I would say SB recommends 3k as the lowest point cause people commonly use 1st and 2nd order crossovers. Using a 3rd order, I reckon you'd be fairly good to go down to 3k.

Very good point, something I hadn't considered before. I guess I'll have to play around with it using an active crossover then decide what sounds best before building a passive hp filter.

Looks good, now you just have to seal them all in... could be the fun bit.

Active crossover testing is just cheating, be a real man and guess! But seriously, that is definetitly the way to do it, look forward to your results.

It took a bit or searching, but I was able to find out where the cabinet guys get their material from. Found some 4x8 baltic birch sheets in 1/2" and 3/4" for the baffle. It was a bit more expensive than I was hoping ($50 for 1/2 and $62 for 3/4), but nevertheless I picked them up anyway. They also had some "paint grade" non-baltic birch that looked like it would work great and was only $26 for 1/2" and a bit more for the 3/4" thick; however, apparently paint grade is synonymous with "this stuff is cheaper so let's scratch and ding the crap out of it when we move it around the warehouse." Needless to say, I stuck with the baltic.

One of the outer plies was quite thin on both sheets, so I'll have that face the inside of the cabinet:



I'm hoping to route these later today...

Routing in progress:

Finished up the routing. Here's a few pics along the way:





An extra baffle, because there was room... and just in case.

Wow, just wow!

Tall son'bitches.

TLAH Pro - "I fear no floor or ceiling!"

Okay so now I really want a cnc router. Where can I get plans?