TLAH and curved SLA

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ecut1
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TLAH and curved SLA

#1 Post by ecut1 »

I bought plans this morning and I'm currently in the process of locating speakers for my TLAHs and curved SLA build. I probably won't build them for a couple weeks but I thought I might as well get parts on the way. I think I'm going to go with the aurasound 525 for the drivers. I've seen a few build threads where these were used.

On the tweeters... I have a question. I'm understanding that the tweeter must pick up where the driver leaves off. The aurasound 525 goes up to 6000 Hz. I found a cheap tweeter that shows a range of 6000 - 20000 Hz. (http://www.parts-express.com/pe/pshowde ... 2&scqty=24) - I'm guessing I can bypass that resistor.

Anyway, will I be ok with the tweeter picking right up where the driver leaves off or should I spend more money and get tweeters that go down to 4000 Hz?

Grant Bunter
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Re: TLAH and curved SLA

#2 Post by Grant Bunter »

ecut1 wrote:I bought plans this morning and I'm currently in the process of locating speakers for my TLAHs and curved SLA build. I probably won't build them for a couple weeks but I thought I might as well get parts on the way. I think I'm going to go with the aurasound 525 for the drivers. I've seen a few build threads where these were used.

On the tweeters... I have a question. I'm understanding that the tweeter must pick up where the driver leaves off. The aurasound 525 goes up to 6000 Hz. I found a cheap tweeter that shows a range of 6000 - 20000 Hz. (http://www.parts-express.com/pe/pshowde ... 2&scqty=24) - I'm guessing I can bypass that resistor.

Anyway, will I be ok with the tweeter picking right up where the driver leaves off or should I spend more money and get tweeters that go down to 4000 Hz?
It's probably fair to say that if you look at the charts for individual components in most cabs, there is a bit of overlap between frequency covered, eg in your case quoted above, between the 6K in the aurasounds and tweeters. The custom made filters sought out what goes where.
They can't do that if the response at x frequency isn't available in the components, say the tweets.

I'd want a little overlap, even if it costs more...
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ecut1
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Re: TLAH and curved SLA

#3 Post by ecut1 »

Thanks for the info Grant. I'll make sure I get an overlap between the drivers and tweeters.

I'm starting to put together an order for all the drivers, tweeters, and crossover hardware for this project. I gotta be honest, I'm reading the plans and scratching my head. :?

I'm planning on using the aurasound 5.25" drivers because the deal can't be beat. I'll use the buyout tweeters at parts express that go down to 4000 Hz. My first question is: with eight 5.25" drivers and twelve 3/4" tweeters will I be ok with the vertical dispersion? My woofer line will end up about 10 inches longer than it would with 4" drivers. The plans say "half to three quarters the length". Looking at the plans I think I'll end up at about half. This is my first stab and building something like this so I honestly have no idea.

My second question is on the crossovers. I'm getting a bit confused trying to figure out the impedance/crossover frequency to enter on the website listed in the plans. Apparently it's not as simple as just taking the rated 8 ohm impedance. I have a chart but I don't know what frequency to choose for the crossover. Should I just go with 5000 Hz so there is some overlap from the drivers and the tweeters?

Also, when figuring the total impedance of the entire TLAH - what the amp sees. Do you add the driver line and the tweeter line together? Or do you just get them as close to the same (up to the 2:3 ratio)? I would think if both lines were an 8 ohm load the amp would either see 4 or 16. Perhaps the crossover makes the amp see an 8 ohm load if both lines are an 8 ohm load?

Sorry... I'm the newbie. :oops:
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Tom Smit
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Re: TLAH and curved SLA

#4 Post by Tom Smit »

Sorry... I'm the newbie. :oops:
No worries. I'm still learning.

As far as the impedance is concerned, it depends on the frequency. Below the cross-over will be what the woofer line is: above will be the tweeter line. We'll just say that it's in a constant state of flux. 8)
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Michael Ewald Hansen
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Re: TLAH and curved SLA

#5 Post by Michael Ewald Hansen »

With this woofer I wouldn't run them as high as 5khz and 4khz is still pushing it with the break-up around 4khz.. I would say that you should low pass the woofers at 3-3.5khz and high pass the tweeters at 4khz, that way you could control some of that peak at 4khz :) Do you have an active crossover and some measuring equipment? Then you can test which crossover is the best..
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ecut1
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Re: TLAH and curved SLA

#6 Post by ecut1 »

Michael Ewald Hansen wrote:With this woofer I wouldn't run them as high as 5khz and 4khz is still pushing it with the break-up around 4khz.. I would say that you should low pass the woofers at 3-3.5khz and high pass the tweeters at 4khz, that way you could control some of that peak at 4khz :) Do you have an active crossover and some measuring equipment? Then you can test which crossover is the best..
I don't have any type of measuring equipment or an active crossover. If I pass the woofers at 3-3.5khz and the tweeters at 4khz wouldn't I be missing between 1-1.5khz of the frequency range?

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Michael Ewald Hansen
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Re: TLAH and curved SLA

#7 Post by Michael Ewald Hansen »

ecut1 wrote:
Michael Ewald Hansen wrote:With this woofer I wouldn't run them as high as 5khz and 4khz is still pushing it with the break-up around 4khz.. I would say that you should low pass the woofers at 3-3.5khz and high pass the tweeters at 4khz, that way you could control some of that peak at 4khz :) Do you have an active crossover and some measuring equipment? Then you can test which crossover is the best..
I don't have any type of measuring equipment or an active crossover. If I pass the woofers at 3-3.5khz and the tweeters at 4khz wouldn't I be missing between 1-1.5khz of the frequency range?
Nope, there are only 1000hz from 3 to 4khz.. Anyways, if you low pass with a 2nd order low pass at 3khz it means that the woofer will be attenuated 12db at 6khz, because a 2nd order crossover is 12db/oct and every doubling of frequency is an octave. That means, if you cross them a bit lower than the breakup peak, you'll smooth out some of that peak and get a more linear response - its not like the output disappears after the crossover :)

Does that make sense? :)
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ecut1
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Re: TLAH and curved SLA

#8 Post by ecut1 »

Michael,

I sort of understand what you're saying. I'm starting to process all this a little more. Thanks so much for your help with this and some of my other threads. You've given me tons of good info!

I ended up buying the aurasound 525 bulk pack and I found some tweeters made by audex that were overstock from harman. They were on a website called apexjr.com. They were only 50 cents each so I figured I'd give them a try.

Without an active crossover do you think I'll be able to get pretty close with my crossover if I used the website listed in the plans?

ecut1
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Re: TLAH and curved SLA

#9 Post by ecut1 »

In my first reply I understood we were only talking about 1000hz, I think I just typed it wrong. However, I was under the impressing the crossover would cut all sound after the point you crossed it over.

I may need some help with the crossovers. :oops:

ecut1
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Re: TLAH and curved SLA

#10 Post by ecut1 »

Tweeters showed up today. :hyper:
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miked
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Re: TLAH and curved SLA

#11 Post by miked »

So_much_soldering to do. :loler: But hey, the "DI" in "DIY" is half the fun, right? :D Hopefully you bought a few extra, just in case you have a dud or two?

ecut1
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Re: TLAH and curved SLA

#12 Post by ecut1 »

Yeah, I should have several extra. I'm currently trying to decide how many drivers/tweeters to put in each. I'm using the same 5.25" aurasound drivers that MissleCrisis used in his. I'm thinking I'll do the same as he did and use 6 drivers and 9 tweeters per TLAH.

ecut1
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Re: TLAH and curved SLA

#13 Post by ecut1 »

The aurasound drivers arrived yesterday. They're not much to look at but they fit the specs good and the price was unbeatable. I'm still torn on the amount of drivers/tweeters to use. If I go with 6 drivers and 9 tweeters I'll have 12 drivers left over and 25 tweeters left over (after building the curved SLA). Obviously the "overkill" side of me kicks in and says put 9 drivers and 12 tweeters in each TLAH (or even more). :loler:

After talking with MissleCrisis about his build I don't know if there will be much of a benefit to doing that. The room isn't huge... I'd say "medium sized" (about 12'x30') with most of the seating about 15 feet back from the screen.

What do you all think about the number of drivers to use? I'd like to hear a few different opinions. :feedback:

I think I've read just about every TLAH build thread on this board. Most of them have a ton of good info but it seems the threads end before the build ends.

I'll probably get wood for the baffles tomorrow and start making sawdust!

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Bill Fitzmaurice
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Re: TLAH and curved SLA

#14 Post by Bill Fitzmaurice »

You don't need to use as many tweeters as midbasses for power, nor for the vertical pattern control. But you don't want the tweeter line to be less than perhaps 80% of the midbass line height, or the vertical patterns of the tweeters and midbasses at the crossover will be very different. That results in having to use more tweeters than midbasses.

ecut1
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Re: TLAH and curved SLA

#15 Post by ecut1 »

Bill, thanks for the reply with the extra info!

I went out in the garage and laid out 8 drivers and 12 tweeters (in the plans all the diagrams show that number of speakers).

So if I'm understanding this correctly the height of my tweeter line is way too short. It's right at about 50% of the driver line. I either need to add more tweeters or reduce the amount of drivers? However, if I go 6/12, or 8/16 then I'm at a 1/2 ratio and I have read in other threads that I need to be at a 2/3 ratio. Perhaps the extreme budget speaker buying is coming back to bite me.

Can I space the tweeters a bit further apart or will that result be negative?
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