BillFitzmaurice.info

I don't have the plans in hand yet, so please bear with me....

A. Is there room on the baffle to fit Dayton PT2C-8 Planar tweeters, even if they touch the drivers and the outer perimeter?

2. Is the location of the port / handle-cutout particular to its function? It's not taking advantage of a node/ anti-node of the air mass where it's located is it? I'd like to place a pivot mounting plate there instead and move the cutout elsewhere if possible....perhaps further aft at best.

D. Where are we supposed to formally post questions about the TLAH Pro and SLA Pro nowadays??

Radian wrote:Where are we supposed to formally post questions about the TLAH Pro and SLA Pro nowadays??

Yeah, it was a bit odd posting my TLAH Pro questions under home theater.

I don't have the updated Pro plans for the SLAH, so I can't say on the measurements... but it looks like you'd need 4 of these for each cabinet to keep up with the alpha 6a's, unless you plan on attenuating the alpha's which would make you lose a few db of sensitivity. I entertained the idea of using ribbons or planars in my TLAH Pro build, but didn't want to give up the sensitivity if I only went with two... and didn't want to have to buy these: http://www.madisoundspeakerstore.com/ri ... n-tweeter/

If I remember correctly, Brent Evans had someone build him some DR200's with a couple of these planars per cabinet. I'm guessing he also had to attenuate his mids/lows of the DR since it has an inherent sensitivity of 104db, paired with the 97db sensitivity of two PT2C's. Quite a big gap... Especially when they only handle 1/3 the power of a delta pro 8. I think high sensitivity is one of my favorite things about Bill's designs. It's hard for me to just throw it away so I can use ribbons... unless I want to pay a fortune for higher power handling/higher sensitivity versions.

Radian wrote:I don't have the plans in hand yet, so please bear with me....

A. Is there room on the baffle to fit Dayton PT2C-8 Planar tweeters, even if they touch the drivers and the outer perimeter?

Not without a mod... but a mod well worth the effort. I believe it adds about 2 inches in width to the standard cab, and in the set I am having built, we made that change and kept the volume similar with extra bracing for flypoints... styrofoam in the cab would be just as effective. They can fit 4 of the tweeters, I spec'd two, as they will be single cabs per side, and 2 is plenty for the volume levels I need, plus I don't want laser beam dispersion... I wanted about 20 degrees, and this is what I expect based on the 16" hf section.. about the same as a DR or OT. If you were stacking them, you'd want four.

GirlyHandedDog wrote: I don't have the updated Pro plans for the SLAH, so I can't say on the measurements... but it looks like you'd need 4 of these for each cabinet to keep up with the alpha 6a's, unless you plan on attenuating the alpha's which would make you lose a few db of sensitivity. I entertained the idea of using ribbons or planars in my TLAH Pro build, but didn't want to give up the sensitivity if I only went with two... and didn't want to have to buy these: http://www.madisoundspeakerstore.com/ri ... n-tweeter/

A few points - the Daytons' sensitivity (and power handling) is a bit understated, but I have found that sensitivity alone isn't everything. Output is sensitivity times power handling, and ribbons (tweeters in general, for that matter) don't experience the power compression woofers do. Two series wired Dayton ribbons keep up perfectly with the Beta 8 in a DR200. Bear in mind that this system is biamped, so sensitivity matching isn't important, but output matching is. Four of the ribbonswill probably outrun the woofer section in program max output in a SLAPro, quite honestly.

So... you do the math and it doesn't add up... the numbers say that the Dayton ribbons will be 6db less than the woofer horn at full power. That's relevant... only if your concerts are pink noise (and I've heard some that are close). In the real world, there is FAR less HF content than mid content, so you simply drive the ribbons a bit harder... they keep up fine. How do you think commercial cabs get away with putting a 500w woofer and a 150w tweeter in the same cab? At that... most of the time you're padding down the HF section of a cab... people even build Jacks with switches on the tweeters around here... OEM crossovers have resistors, etc.... all of this is becasue in music program, HF just doesn't take as much.

If I remember correctly, Brent Evans had someone build him some DR200's with a couple of these planars per cabinet. I'm guessing he also had to attenuate his mids/lows of the DR since it has an inherent sensitivity of 104db, paired with the 97db sensitivity of two PT2C's.

This frame of thinking doesn't work when biamp, since matching output matters more than sensitivity. In any case, the piezo array isn't the most sensitive part of the cab, so it's no matter. The 104 "average" isn't borne out in the chart, as well.. it's more like 101-102, and this matches with my own measurements.


And here's my cabs, meausered referenced at 1w/1m (actually 28.3v/40v at 10m for each section (hf section is 16 ohms):

Quite a big gap... Especially when they only handle 1/3 the power of a delta pro 8. I think high sensitivity is one of my favorite things about Bill's designs. It's hard for me to just throw it away so I can use ribbons... unless I want to pay a fortune for higher power handling/higher sensitivity versions.

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There's no real world gap. My DRs actually got louder and smoother when I made the change... this is probably a combination of extra chamber volume (no piezo horns in the array means more chamber volume), no passive crossover voltage loss, and the ability to take the individual drivers up to max safely.

The Dayton ribbons definitely work in the DR200, I know they will work in the SLAPro because I have a colleague that builds a similar cab this way (with the Dayton mids as well, which is what are going in my pair) and they should also work in J10, J12, and OT12 with 2 per cab (based on charts). I'd be hesitant to put only 2 in a DR250, 3 might do it, but they might not... I don't know. Bill said it took 6 when he tried years ago.

All I can say is I'm very happy with my DRs, and I know I will be with the SLAs. Those are for the church... I wouldn't be spending the church's money on them if I wasn't sure.

And.. hot off the camera... here they are (along with their 1/2 size sidefill brothers with 1005 piezos).

I'm thrilled to see so much sudden interest in the SLA Pros. Also the Dayton planars, which I've been curious about for a while. Too bad they've doubled in price since the whole Neodymium fiasco. I still have a PE catalog in the john where they're $38 apiece. *sigh* Shoulda bought a few.

Brent, thanks for posting the info. One of these days I'll pimp Bill for the updated plans. There's good reason to get spun-up about the SLA Pro.

I'm in this deep so far:

SirNickity wrote: I still have a PE catalog in the john where they're $38 apiece. *sigh* Shoulda bought a few.

Exactly where I keep mine. Just checked and its a 2009 catalog. My how time flies when your having ...

This thread was peaking my interest until I checked PE for the updated prices. $76.75 for one x two or four and im back to peizos with eq for me.

Wow.... Didnt realize the cost had risen so much.

Yeah, same deal with those Alphalites in that pic. PE has the Alpha for about $40, Alphalite for $140. Yikes! Multiply that by 4 per cab and it really adds up.

BrentEvans wrote:Bear in mind that this system is biamped, so sensitivity matching isn't important, but output matching is. Four of the ribbonswill probably outrun the woofer section in program max output in a SLAPro, quite honestly.

And as you mentioned, max output is sensitivity times power handling. There's a ceiling where you run out of powerhandling before you're able to get the db needed to keep up with a delta pro 8 running at 225 watts. Now, if you don't need to realize the full output levels that a DR200 is capable of, then it doesn't matter.

BrentEvans wrote:In the real world, there is FAR less HF content than mid content, so you simply drive the ribbons a bit harder... they keep up fine.

Regardless of the HF to mid balance, that doesn't change the fact that when there is HF content it still needs to hit a certain output level to keep up with the mids. Having less HF content doesn't change the output requirements for that content when it's there.

BrentEvans wrote:How do you think commercial cabs get away with putting a 500w woofer and a 150w tweeter in the same cab?

I'll assume you're familiar with the difference in sensitivity between compression drivers and woofers. A woofer with 90db sensitivity is going to take a lot more voltage to keep up with a compression driver with 110db sensitivity.

BrentEvans wrote:The 104 "average" isn't borne out in the chart, as well.. it's more like 101-102

I was referring to Bill's chart with the delta pro 8. Take a look at it, it's not 101-102. If you put the beta 8's in your DR's, that's a different story... but that's not what I was referring to when I mentioned 104db.

The handle/ports can be located on the back. Don't know if that helps with your question any...

Radian wrote: I'm in this deep so far:

Now that is a beautiful site to behold.

GirlyHandedDog wrote: And as you mentioned, max output is sensitivity times power handling. There's a ceiling where you run out of powerhandling before you're able to get the db needed to keep up with a delta pro 8 running at 225 watts. Now, if you don't need to realize the full output levels that a DR200 is capable of, then it doesn't matter.

Regardless of the HF to mid balance, that doesn't change the fact that when there is HF content it still needs to hit a certain output level to keep up with the mids. Having less HF content doesn't change the output requirements for that content when it's there.

Again, these things are only relevant if the content is pink noise. Sometimes I think we audioheads are just as guilty about listening with our eyes as anyone else, except our eyes are on charts and specs. The natural balance of program content is absolutely relevant in this context - you simply don't need the HF output capability unless you're running full bore pink noise... and nobody does that. The HF section can be 3db down in max output (which is about what the ribbons are with the DRs, BTW) and you will NEVER hear the difference in program content because the woofers run out before the tweeters will. I've tested it. This is the result, not a speculation based on reading threads and specs.

I'll assume you're familiar with the difference in sensitivity between compression drivers and woofers. A woofer with 90db sensitivity is going to take a lot more voltage to keep up with a compression driver with 110db sensitivity.

Feed pink noise to an average MI commercial cab and turn the volume up until one driver or the other blows. Most of the time the HF driver will go first. HF drivers nearly always have less output capability than mids... becasue program content has more mids than HF.

I was referring to Bill's chart with the delta pro 8. Take a look at it, it's not 101-102. If you put the beta 8's in your DR's, that's a different story... but that's not what I was referring to when I mentioned 104db.

I believe I posted that very chart. 104db is about average from 100hz-500hz, but the whole bandpass average is about 102. And the beta doesn't really change it that much, just a smidge less output.

Okay, enough bickering... Radian, let us know how your build works out!

GirlyHandedDog wrote:Radian, let us know how your build works out!

Will do.

bzb wrote:The handle/ports can be located on the back. Don't know if that helps with your question any...

Sure does! Thanks!

Radian wrote: 2. Is the location of the port / handle-cutout particular to its function? It's not taking advantage of a node/ anti-node of the air mass where it's located is it?

The cab is about a tenth the size required for port location to be of any consequence.