Home Brew FRFR

[mayfly]

As it happens, Theresa and I are doing smaller shows these days as a duo.  It's a lot easier than herding the cats to pull off a full gig and the gigs are more plentiful.  However, at these shows the Bose poles are very much over kill.  On top of that, stages are small and we're usually positioned right in front of them, where the comb filtering of the array is very noticeable and pretty annoying after awhile.  On top of THAT I realized I'd like a little FRFR for playing with friends.

Looking around at PA speakers, I found that there are a LOT to choose from.  But they all kinda suck actually.  After auditioning several name brands I wondered if it was worth doing it myself.  Then found that eminence makes a line of co-axial speakers.  Thinking that point source (and I mean point source) would be the way to go after one to many comb filtered gigs, I jumped in and ordered an Eminence beta 8CX and crossover.

The 8CX (and it's larger brothers) has been around for awhile, but I had never heard of it.  I learned about it through an excellent article published by the eminence guys:  http://www.eminence.com/2012/10/great-uses-for-coaxial-products/.  Essentially it's a mid bass driver that you can screw a compression driver on to at the back.  The cone of the speaker itself forms the horn, with the dust cap being acoustically transparent.  Now that's about as point source as you can get!  And it was fairly small and quite efficient.  Sounded like just the thing.  Here it is with the crossover.

More later.

update - fixed the text for the speaker that I actually used!

 

[swarfrat]

8CX is in the running for a FRFR guitar/drum/bass monitor for my 11R/electronic drums. Make sure you pay attention to the excursion limits though - WinISD pro does excursion calculations. This is one area where a lot of commercial cabinets fall down and don't tell anyone.  Sure it's a 400W cabinet, but it could well be limited to 80W at 50 Hz.

 

[mayfly]

Yepper.  It seems that any 'pa' type speaker has a paper surround and spider - which means not a heck of a lot of excursion before they break.  I think this is why manufacturers use a lot of 15" woofers and horns - just to hit some sort of magical 3db down point.

I figure if I really need low end I can make a sub.  However for guitar and vocals I'm thinking that limiting things to 80Hz is probably just fine.

 

[swarfrat]

In the case of the Beta 8 CX - xmax is 3.2mm, and in a more or less flat cabinet (17l, 79 Hz, -3db @ 75Hz) there's still an excursion limit at 55W @ 110 Hz for 113 dB). It's something I can live with in most applications I've considered the driver for. But it's not a Man O War cabinet.

 

[mayfly]

Hmmm.  I'll have to be more careful as 110Hz is easily something that the speaker will see.  However, I don't think that 113db is quite appropriate for those small gigs so I'm probably ok.

 

[mayfly]

Hey!  I just ran into this:

http://www.diysoundgroup.com/coaxial-speaker-kits/volt-8lx.html

Not sure if this is old or new or what the deal is, but it's pretty interesting.

 

[swarfrat]

These guys are making a lot of noise in the bass world:
http://greenboy.us/

Not super cheap, but quite capable.

 

[mayfly]

Yea I heard of those guys from Leland Crooks.  There's also Bill Fitzmaurice, but maybe we should not go there...  :evil4:

 

[swarfrat]

Fearful is primarily a DIY proposition, but you can always pay someone if you don't want to get dirty.

 

[bagman67]

You do know you're talking with Mayfly, right?

 

[swarfrat]

LOL, yeah. I was just explaining the various vendors which might have more of an online presence than Fearful as DIY.

 

[mayfly]

Update - whipped up a prototype out of 1/2 plywood.  I just used the canned Eminence "medium box ported" design and I got the nice boys at Rona to cut the wood to my cut sheet.

A little titebond and some screws and this is the result

 

[Cagey]

Tweeter behind the woofer dustcover or what?

 

[swarfrat]

I can't speak highly enough about using a crosscut sled on a table saw for building boxes. I made three or four speaker boxes before getting one. When I made one with it - I was surprised how much tighter the boxes went together.

 

[mayfly]

Tweeter behind the woofer dustcover or what?

Yep that's right

 

[mayfly]

I can't speak highly enough about using a crosscut sled on a table saw for building boxes. I made three or four speaker boxes before getting one. When I made one with it - I was surprised how much tighter the boxes went together.

I got rid of all my power saws (except inexplicably the sawsall).  I'm pretty happy with the quality of the Rona cut shop - they have one of those big industrial saws and they take the time and care. And for me they do it for nothing!  Cool!

Speaking of quality, the box sounds ok, but has a bit of a midrange honk.  But all the frequencies seem to be there.  I'll probably try less stuffing later.

 

[mayfly]

Update - removed some stuffing and the sound improved dramatically.  Sounds pretty good!  I think I should use foam liner for the final one.

 

[Cagey]

Maybe I'm not remembering your Bose system exactly, but it doesn't seem like these units would be that much less in-your-face. Then again, some of those Bose designs can be almost magical.

 

[mayfly]

The Bose poles we run are the original L1 'personal PA' speakers - Bought em used on eBay.  They are line arrays with 24 2" speakers and subs.

They are pretty good for larger shows with more area on stage, but for small places when you are up close to them you can really hear the comb filtering of the array.  It bugs us.

 

[Cagey]

I see. And now that you mention it, I think you already said so earlier in the thread. Sorry - I forgot.