SLA pro for bass

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scorpiomoon75
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SLA pro for bass

#1 Post by scorpiomoon75 » Sat Nov 21, 2020 11:23 am

Hi
I bought the SLA pro plans a while ago just for fun. I was interested in building a tweeterless 4x4 or two of them to use as a midbox with my tweeterless SImplex 212. I was thinking of crossing over at 800HZ or so using the crown XLS DSP.

Could these cabs be suitable for bass?
Or would a 4x6 or two of them work better, If i was to build a 4x6 I was going to leave out the tweeters and center the drivers on the baffle the same as the tweeterless 4x4.

The Alpha 6A sensitivity is 93.6 db so would 2 of them gain 3db (96.6 db) and 2 more in the case of the 4x6 have a sensitivity of 99.6 db Then adding another 4x6 would have a sensitivity of 102.6 db. Is that how it works, or do you gain 3db for each driver?

I know the alpha 6A is used in fearful cabs as a mid and people seem to like them for mids in their bass cabs. Trace Elliot and hartke made midboxes many moons ago...and the new Genzler cabs use a 4x4 mid design in their new cabs.

These drivers are fairly cheap, I made some templates for handles today but thought i would see if i could get some feedback before I proceed.

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Bill Fitzmaurice
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Re: SLA pro for bass

#2 Post by Bill Fitzmaurice » Sat Nov 21, 2020 12:27 pm

There's no reason to add a midbox to the S212, which is perfectly adequate to at least 3kHz without assistance. Built with bass drivers and tuned for them the SLA Pro could work by itself for bass, but sixes that will handle bass are expensive, and it would take four of them to equal one twelve, so it's not cost effective.

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Re: SLA pro for bass

#3 Post by scorpiomoon75 » Sat Nov 21, 2020 2:24 pm

Hey Bill
Thanks for the response, the midrange response in the simplex is pretty amazing. I had a feeling their might be no advantage.

In regard to the tweeterless SLA pro 4x4, the alpha 4's have a response to 12K, would their be any usable higher frequencies from 3k up? In comparison to the BGH-25 they are less sensitve but have more power handling. I havent played a tweetered cab for a long time. I was curious if one of these could work as a more subtle alternative to a tweeter.

I'm in the mood for building something so its looking like a Simplex 12 Tweeter version is the way to go.

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Bill Fitzmaurice
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Re: SLA pro for bass

#4 Post by Bill Fitzmaurice » Sat Nov 21, 2020 3:52 pm

Compared to commercial bass cabs, which are loaded with cheap PA tweeters crossed over at 3.5kHz or higher, Alpha 4s would be better, but the BGH-25 is a quality bass specific tweeter, which we cross over at 2kHz using a 4th order crossover. The BGH-25 rating of 25 watts is high frequency content only. It's equivalent to 800 watts at 60Hz.

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Re: SLA pro for bass

#5 Post by scorpiomoon75 » Sun Nov 22, 2020 10:35 am

Hey Bill

Thanks for the response. Sorry my first question was a bit convoluted...

So theoretically the SLA pro 4x4 could work ok crossed over or high passed at 3 - 3.5K, four of those drivers are the same price as two BGh-25's. It could be an economical option to add some highs if i didnt want to build a tweetered S12.

OR

The crown XLS uses linkwitz Riley 4th order crossovers, so just say i built a tweeter box with 2 BGH-25's and crossed them over at 2k would it be the same? It would be even more economical.
I'll assume it's more complex than that and the crossovers you use were engineered for the simplex with more scientific factors considered.
A while ago I was looking at an online crossover calculator just trying to learn more about crossovers and the crossover components.
I couldnt get the components to match up to the ones in the plans, as i remember i the think the high pass did but not the low pass..i cant remember.

Looking at the frequency chart of the Alpha 4's their is a dip at 5k whereas the frequency response chart of the BGh-25 looks really smooth...and as its designed specifically for bass.

Having said all that i ti will just build one or 2 tweetered S12's obviously I could add tweeters to the s212 but most likely i will use distortion when jamming and want to keep it tweeter free, it sounds awesome as is and i dont want to mess with it. It sounds amazing with distortion by the way.
I think it will worthwhile building one or a pair of tweetered s12's for some versatility in sounds for other musical styles and portability, and you can use them with any amp.

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Bill Fitzmaurice
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Re: SLA pro for bass

#6 Post by Bill Fitzmaurice » Sun Nov 22, 2020 11:37 am

A separate tweeter box places the tweeters too far away from the woofers for wavefront integration. The commercial ones you see that have two or more tweeters placed horizontally are even worse, as they have rampant comb filtering.

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Re: SLA pro for bass

#7 Post by scorpiomoon75 » Sun Nov 22, 2020 12:53 pm

Thanks Bill
When you use the term wavefront integration, Im guessing that is how the high frequency is integrated with the low frequency woofer on the baffle, so these frequencies arent bouncing off each other. So the position of the tweeter is integral, not just random or where it fits?
I read a while ago about your thoughts on the problems with 410 cabs an dwhy they shouldn't be made..i cant remember exactly if it was comb filtering
Just observing all the 410's over the years the tweeters are always in the middle, do they just put them there because it's the only place on the baffle they fit? On your s210 and s212 they are in the top right corner
not the middle of the baffle.

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Bill Fitzmaurice
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Re: SLA pro for bass

#8 Post by Bill Fitzmaurice » Sun Nov 22, 2020 1:02 pm

There are two separate wave fronts, one from the woofers, one from the tweeters. For things to sound right those two wave fronts have to become one at a point close to the cabinet. If the drivers are too far apart they won't.

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Re: SLA pro for bass

#9 Post by scorpiomoon75 » Sun Nov 22, 2020 1:29 pm

If you had a 4x4 SLA pro on speaker stand, next to a S212 it wouldnt sound right. The wave front from the SLA pro woofers would have to come to a point with the wave front from the S212 woofers.

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Re: SLA pro for bass

#10 Post by SethRocksYou » Sun Nov 22, 2020 2:16 pm

scorpiomoon75 wrote:
Sun Nov 22, 2020 1:29 pm
If you had a 4x4 SLA pro high passed at 3-3.5kHz on speaker stand, next to a S212 it wouldnt sound right. The wave front from the SLA pro woofers, used as tweeters, would have to come to a point with the wave front from the S212 woofers.
Fixed it for you.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Re: SLA pro for bass

#11 Post by scorpiomoon75 » Sun Nov 22, 2020 2:31 pm

SethRocksYou wrote:
Sun Nov 22, 2020 2:16 pm
scorpiomoon75 wrote:
Sun Nov 22, 2020 1:29 pm
If you had a 4x4 SLA pro high passed at 3-3.5kHz on speaker stand, next to a S212 it wouldnt sound right. The wave front from the SLA pro woofers, used as tweeters, would have to come to a point with the wave front from the S212 woofers.
Fixed it for you.
Thanks :)
I am in a different time zone so probably should rest my brain.

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Bill Fitzmaurice
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Re: SLA pro for bass

#12 Post by Bill Fitzmaurice » Sun Nov 22, 2020 2:41 pm

By having the tweeter arrays coincident with the woofer horns the DRs, OTops and Jacks have perfect wave integration right at the source. That's no accident.

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Re: SLA pro for bass

#13 Post by SethRocksYou » Sun Nov 22, 2020 7:34 pm

Bill Fitzmaurice wrote:
Sun Nov 22, 2020 2:41 pm
By having the tweeter arrays coincident with the woofer horns the DRs, OTops and Jacks have perfect wave integration right at the source. That's no accident.
Just so I'm clear on this... coincident is no coincidence?

:D
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Re: SLA pro for bass

#14 Post by Tom Smit » Sun Nov 22, 2020 9:42 pm

:loler:
TomS

scorpiomoon75
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Re: SLA pro for bass

#15 Post by scorpiomoon75 » Sun Nov 22, 2020 11:49 pm

Ahhhh! I see.
I was looking at it the wrong way. As SethRocksYou corrected me, what I was proposing is using the SlaPro woofers "as tweeters". So having the SLA Pro used as tweeters Separated from the S212 they would too far away for wavefront integration (same problem as a seperate tweeter box as Bill pointed out), it would be like taking the tweeter array off a Jack 12 and moving away from its position of perfect wave integration right at the source.

"By having the tweeter arrays coincident with the woofer horns the DRs, OTops and Jacks have perfect wave integration right at the source. That's no accident."
when you put it that way, it's seems more obvious....I wouldnt have assumed their was any accident or coincidence to those designs.
Sorry for these questions and thanks for your responses and patience.I curious about this for a while but i was intimidated to ask questions because i knew i wouldn't understand the answers...but im think i understand now...

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