Random SLA and SLA Pro questions

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kmmcgrew
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Joined: Thu May 14, 2015 10:57 am

Random SLA and SLA Pro questions

#1 Post by kmmcgrew » Thu Feb 02, 2017 12:06 am

Hello - I've been studying the SLA and SLA Pro plans and options within those plans and have a few questions. I understand the design intent of the regular SLA and the Pro version are different and maybe that is what drives the differences.

1. SLA is a sealed cabinet and SLA Pro is vented. But they both cover the same basic frequency range of 100Hz and up and are best used with subs. What is the ported cabinet doing for the Pro's?

2. SLA uses a full crossover for the both the lows and highs. SLA Pro only uses the high pass filter for the piezos. I understand the piezos are a different animal but I'm more curious why the SLA Pro runs the mid bass drivers full range. It seems the recommended Alpha 6A driver has a tame high end roll off response rather than the break up seen in other drivers. Is this the reason?

3. Latest SLA Pro plans call out the option of running the Alpha 4 standalone without tweeters. Even though the Alpha 4 has decent high frequency response won't the off axis response be pretty poor because of the large cone? Maybe you would only pick this option for voice only PA applications?

To put this last question another way - there is a comment in the crossover section the SLA Plans "If you don’t have a chart don’t run a four inch woofer past 6kHz, or a five inch past 5kHz, with lower by a kHz usually being better" . What drives this recommendation? Is this the decreased dispersion at high frequencies, the driver breakup, or ???

Simply - what good is a 4 or 5" driver with full range response if you run into these other limitation that can only be solved by adding a proper high frequency section.

Thank you for the help!

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Bill Fitzmaurice
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Re: Random SLA and SLA Pro questions

#2 Post by Bill Fitzmaurice » Thu Feb 02, 2017 7:58 am

kmmcgrew wrote: 1. SLA is a sealed cabinet and SLA Pro is vented.
High Q versus low Q drivers.
I understand the piezos are a different animal but I'm more curious why the SLA Pro runs the mid bass drivers full range. It seems the recommended Alpha 6A driver has a tame high end roll off response rather than the break up seen in other drivers. Is this the reason?
Correct.
Latest SLA Pro plans call out the option of running the Alpha 4 standalone without tweeters. Even though the Alpha 4 has decent high frequency response won't the off axis response be pretty poor because of the large cone?
I wouldn't say poor, just not as good as with tweeters, which isn't critical at longer listening distances.
To put this last question another way - there is a comment in the crossover section the SLA Plans "If you don’t have a chart don’t run a four inch woofer past 6kHz, or a five inch past 5kHz, with lower by a kHz usually being better" . What drives this recommendation? Is this the decreased dispersion at high frequencies, the driver breakup,
Both. It's more of a concern with a cab for home use where the likelihood is a closer listening distance and lack of sophisticated EQ.

kmmcgrew
Posts: 2
Joined: Thu May 14, 2015 10:57 am

Re: Random SLA and SLA Pro questions

#3 Post by kmmcgrew » Thu Feb 02, 2017 10:53 pm

Thanks for the reply Bill.

I also just found the answer to questions #2 in the plans....

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