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Simplexx 15: Design overlap vs. Compromise?
Posted: Wed Mar 17, 2021 5:36 am
by supertzar
Hello.
I'm looking at building a pa sub for my band. Nothing too big. At the moment I'm fairly certain that a single 15" sub would be enough to add just that little extra to the situations where we have to use our own pa.
I got a nice offer for a couple of Faital drivers and by the plans I believe either 15FH500 or 520 should be ok to use as a subwoofer.
But I also play bass so I started thinking about the possibility of also trying the same cab for bass. I heard the 15PR400 is great for bass and the 15FH520 has same frequencies in the spec sheet. I can cut plywood and follow instructions but I'm not too familiar with the science behind speaker design. Could the same cab work getting the full range bass guitar from my amp AND getting the low passed signal from our pa (Not at the same time obviously)?
I have a nice bass rig already, so if the idea isn't viable I will just continue with building a pure subwoofer.
Re: Simplexx 15: Design overlap vs. Compromise?
Posted: Wed Mar 17, 2021 7:07 am
by Bill Fitzmaurice
It could be done, but the response of the S15 sub will go a bit lower because the cabinet is larger and it's tuned lower. As for only needing one sub for PA, sure, if that PA is a pair of eight inch tops. Subs are to mains as the size of an iceberg below the waterline is to that which can be seen above. The wave lengths they handle are at least twice as long as that which the mains handle, as must be the size differential.
Re: Simplexx 15: Design overlap vs. Compromise?
Posted: Wed Mar 17, 2021 9:50 am
by supertzar
Funnily enough, you got that one absolutely right. The tops for this would be an old 8" yamaha stagepas system that we use(-d to use) for the smallest events. Mostly vocals and acoustic guitar and usually in a corner of a little pub without actual stage or pa. Anything bigger, and here would either be foh provided by the venue or then we would just be towing "the big rig" with us.
Most of the time the yamaha works as it is. But as the drummer uses either a cajon or a loota percussion mic'd, I often find myself wanting that little extra oomph even if it would be only for the kick.
And I enjoy building stuff.
And this could potentially end up as an extra bonus for me personally in the bass guitar side of things.
So in this context, I am basically asking someone smarter than me to greenlight the idea where I accept to compromise for a double purpose cab. Would a Simplexx 15 with 15FH520 add any meaningful value to a 8" yamaha stagepas system that has a crossover at 120Hz when used with a subwoofer?
Re: Simplexx 15: Design overlap vs. Compromise?
Posted: Wed Mar 17, 2021 9:56 am
by Bill Fitzmaurice
It would add plenty.
Re: Simplexx 15: Design overlap vs. Compromise?
Posted: Wed Mar 17, 2021 9:58 am
by Bruce Weldy
supertzar wrote: ↑Wed Mar 17, 2021 9:50 am
Funnily enough, you got that one absolutely right. The tops for this would be an old 8" yamaha stagepas system that we use(-d to use) for the smallest events. Mostly vocals and acoustic guitar and usually in a corner of a little pub without actual stage or pa. Anything bigger, and here would either be foh provided by the venue or then we would just be towing "the big rig" with us.
Most of the time the yamaha works as it is. But as the drummer uses either a cajon or a loota percussion mic'd, I often find myself wanting that little extra oomph even if it would be only for the kick.
And I enjoy building stuff.
And this could potentially end up as an extra bonus for me personally in the bass guitar side of things.
So in this context, I am basically asking someone smarter than me to greenlight the idea where I accept to compromise for a double purpose cab. Would a Simplexx 15 with 15FH520 add any meaningful value to a 8" yamaha stagepas system that has a crossover at 120Hz when used with a subwoofer?
Sure, it will definitely help. Based on your use - should be just fine. And as to whether it will be good for bass guitar - you'll just have to try it and see. Might not have the highs you'd like depending on your style and genre of music you play.
Re: Simplexx 15: Design overlap vs. Compromise?
Posted: Wed Mar 17, 2021 10:58 am
by Bill Fitzmaurice
He can always put in a HF horn if that's the case.
Re: Simplexx 15: Design overlap vs. Compromise?
Posted: Wed Mar 17, 2021 1:28 pm
by Bruce Weldy
Bill Fitzmaurice wrote: ↑Wed Mar 17, 2021 10:58 am
He can always put in a HF horn if that's the case.
ahhh.....I was assuming he meant the Simplexx 15 Sub version.....but, I guess that's not the case. Mea Culpa....
Re: Simplexx 15: Design overlap vs. Compromise?
Posted: Wed Mar 17, 2021 2:08 pm
by Bill Fitzmaurice
Yeah, the sub can't do double duty, the regular S15 can.
Re: Simplexx 15: Design overlap vs. Compromise?
Posted: Wed Mar 17, 2021 11:18 pm
by supertzar
Sounds great. I also figured adding the tweeter later would be simple enough to not worry about right now. The plans talk about the xmax when using the cab as a sub and I assume this is to really get those low frequencies moving. I understand that FH520 is definately better, but would the PR400 be enough for this purpose? The price difference isn't that much but the possiblity of keeping the whole build well under 200€ seems intriguing.
Re: Simplexx 15: Design overlap vs. Compromise?
Posted: Thu Mar 18, 2021 12:56 am
by Seth
Links to the specs would be handy
Re: Simplexx 15: Design overlap vs. Compromise?
Posted: Thu Mar 18, 2021 1:08 am
by Grant Bunter
If there isn't much in it regarding price, go with more Xmax.
Displacement is king, especially so in subs.
Vd (Peak Volume displacement) is the parameter, and it arrived at by multiplying Xmax x Sd.
I didn't do the math, but I'm pretty sure the FH520 will win if you compare Vd.
Since you're planning building only 1 cab, give it every chance it can have. If you end up regularly hitting a limiter with the cab, it's time to build another.
Under 200 Eu, 200 Eu, just over 200 Eu, doesn't matter in the end.
I doubt you will find a new commercially priced cab at retail for anywhere near that...