Building a cab for a Faital 15fh500

[SlimNeck]

Hi all,

I’ve been lurking around here for a good while but this is my first post.

I’m intrigued to build a couple of 115 cabs with fairly small form factors to go with my TH500 for a portable yet capable rig. I know and am well aware it won't save me money to diy nor should I expect spectacular results in a first design without any proper experience. Anyways, my curiosity tells me to go ahead. Best way to learn right?

The tonal goal is a fairly neutral and open sound with a nice low end without being boomy. Trebly sizzle is not my thing so they might do without tweeters too. I’m currently playing various 10’s and 12’s but I’ve also gigged some 15” backlines and kinda liked what I've heard.

So I’ve played around with various online T/S resources to calculate and outline a few ideas. (I’m a mac user and unfortunately can’t run WinISD)
The speakers I’ve been looking at is Eminence 3015 (non lf), Faital 15pr400 and Faital 15fh500. I read a lot of good things about all of these but I’ve dialed in to the Faital 15fh500 at the moment. Reason being it looks like it works slightly better in a small(-ish) box than the other two. At least that’s my conclusion. My calculations are based on 2.5 - 2.7 cu ft V(b) and trying to hit a F(b) around 45Hz. I’m playing a 4 string so that should be a reasonable goal, right? The plan is to use 2 x 4” round ports and a length of around 9.5”. I hope 2 ports like these are large enough to avoid chuffing or should I consider a shelf port with a larger area?

The cabs will be built from 12mm birch plywood with the internal bracing required to keep them stiff. I’m not afraid of the wood working. I’ve built stuff before, including basses and guitars.

Now, these online resources for calculating has their limitations. The graphs aren’t that detailed and i can’t read out anything in the higher register. I was hoping someone with better skills and proper software might be able to do a reality check for me?

I guess this renders out in a couple of questions. Is a 2.5 cu ft box and 45 Hz a feasible goal for ta Faital 15fh500 without considerable trade offs?
Also, being a 15” I guess beaming might be a factor and not much will be going on in the higher register, particularly off axis. Will it still sound ok or should I look for other speaker options or build a bigger box and include a 6” mid driver (or build a fEARful…)?

Just want to validate and get an opinion from you WinISD guruhs and experienced speaker designers here at TB.

Thanks for reading!

 

[Downunderwonder]

Have a look at johnk_10 streamliner with the 15pr40. Sound clips and full design for free.

Your dispersion concern is valid. Ime with JBL E140 on a shallow stage, on the other side the lead guitar struggles to hear what note I am playing. If you are playing to the room then 15's aren't too flash.

So Fearful could be a better bet. Speaker DI and no excuse for FOH to muck up your mix. With the big one you can stand aside and play to a big room and hope they highpass all the mics. You are your own PA.

 

[SlimNeck]

Cool. I've read the Johnk thread a while ago, but I'll definitely have another look.
Thanks!

 

[DukeLeJeune]

I guess this renders out in a couple of questions. Is a 2.5 cu ft box and 45 Hz a feasible goal for ta Faital 15fh500 without considerable trade offs?

That looks very good to me.

Also, being a 15” I guess beaming might be a factor and not much will be going on in the higher register, particularly off axis. Will it still sound ok or should I look for other speaker options or build a bigger box and include a 6” mid driver (or build a fEARful…)?

"Sounds ok" is too subjective for me to say. If in doubt, I suggest leaving enough space below the woofer so that you can go back and install the 5" Eminence Pro 5MRN-8 if you need to. Eminence makes an isolation chamber for this mid.

Imo the Pro 5MRN-8 is an excellent little mid for electric bass. You can run the Faital fullrange and let the little Eminence overlap the top end of the Faital a bit. If you decide you need to install the mid, just turn the cabinet upside-down so that the mid is now above the woofer.

 

[BogeyBass]

I haven't heard the driver but with that much xmax and such high inductance or Le it could be a dark speaker.

nothing like a nice pair of 15" speakers though
going with 15pr400 fullrange be good thing keep in mind, heard those drivers, good highend


if you like small form factor think QB3 alignment was around 3.3/3.4 at 42hz tune
just go straight 3 cubic and tune the same.

velocity on port is good with 2x4" ports good choice, slightly lower would be 4x3" ports basically one port each corner of the box.
both those port setups give decent velocity for power range you can push either faitals

 

[SlimNeck]

Great input, Thanks. I've actually reconsidered and made some new drafts using the 15pr400 in a ~3 cf box. I'm a bit uncertain about the tuning though. I' m considering around 47-48Hz which seems kind of middle ground. What are the pros and cons for tuning lower or a bit higher? From what I understand there is a risk of over excursion below tuning frequency, which would indicate a lower tuning could theoretically save the driver. Or will articulation and responsiveness of the final cab be better off with a slightly higher Fb, say around 55?

 

[SlimNeck]

Imo the Pro 5MRN-8 is an excellent little mid for electric bass. You can run the Faital fullrange and let the little Eminence overlap the top end of the Faital a bit. If you decide you need to install the mid, just turn the cabinet upside-down so that the mid is now above the woofer.

Interesting idea. So you mean just using a high pass for the 5" mid? I guess the added impedance of a mid speaker won't matter higher up in the freq register. At which point would you recommend the mid to blend in?

I really appreciate your view on this. Thanks

 

[DukeLeJeune]

So you mean just using a high pass for the 5" mid?

Yes. That's what I do in my 115 cab that uses the Pro 5MRN-8.

I guess the added impedance of a mid speaker won't matter higher up in the freq register.

Well it's possible to drop the impedance too low, so some care must be exercised. The 15FH500's impedance is about 12 ohms at 1 kHz and just keeps rising as we go up higher. In general, as long as the actual impedance of the cab doesn't dip below about 5 ohms, it's still an "8 ohm" cab.

At which point would you recommend the mid to blend in?

Well to a certain extent it depends on what your tone goals are, but imo somewhere between 1.4 kHz and 2 kHz might not be a bad starting point. I'd recommend third order if you're bringing in the mid down around 1.4 kHz, but second order is probably okay up around 2 kHz. Try the midrange driver in both polarities. Chances are reverse polarity on the mid will be the correct (louder) configuration, but there are enough unknowns when we factor in the phase response of the woofer and mid that imo it makes sense to try it both ways just in case.

 

[SlimNeck]

Thanks for great input, Duke

 

[Triad]

Don't know if it's useful information but I replaced the Sigma 18 with a Faital 18FH500 yesterday... you can see the difference (and I could feel it too, about 6kg).
I'd definitely use a mid, though.