Home Brew FRFR

[mayfly]

No worries buddy!  ccasion14:

BTW - been playing and singing through this thing.  Really liking the coaxial sound  :headbang:

 

[swarfrat]

One other thing about that excursion limit - if you cross over the Beta 8CX at 200 Hz you can take it all the way to thermal limit (about 119db which should be plenty paint peeling for any normal use)

I'm still thinking about building my FRFR with a "sub" for use with drum/bass monitor and only take the 8CX when I just need it for guitar. I have an offlabel Eminence Delta Pro 15 - which is xmax limited, but I can get it in a reasonably flat box and take the xmax limit up to 118db @ 62 Hz, with a -3db point at 47 Hz which ought to pack decent punch for a bass and  drum monitor - at least up close. (If you're talking about using it as a stage/room filling monitor - that 118db @ 1m drops off to 104db @ 10m, which doesn't leave a ton of headroom for deep bass drum transients. If you figure you want 10db peak over the average level - it's  adequate for rehearsal with electronic drums. It doesn't really do justice to my 32" marching bass drum though)

 

[mayfly]

I want to get that alternate version of the betaCX with the different spider and surround.  supposed to have more excursion. 

 

[swarfrat]

source? Have not heard of it.

 

[mayfly]

I mentioned it earlier - these guys:

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

 

[swarfrat]

Thanks, they don't seem to be forthcoming with actual specs though. Not that I could find. Suggested reference designs but no actual parameters.

 

[mayfly]

I plan to reach out to them for details.

 

[mayfly]

God knows how I have time for this, but I went out to Rona and got them to saw up some pine boards. A little work and now I have this guy.  The original box is now empty (and will probably end up in the trash soon)

Forward!

 

[mayfly]

Thanks, they don't seem to be forthcoming with actual specs though. Not that I could find. Suggested reference designs but no actual parameters.

and there's always this...

http://sound.westhost.com/tsp.htm

 

[swarfrat]

Yeah, I need to do that with said "off label Delta 15 Pro" aka MCM 55-765. I even already have a sealed box that I built for it originally that I could use to measure it.

 

[mayfly]

it was a nice day, so I took it out side!  Whipped out the router and put a roundover around the outside of the box.

Nothing like working outside to improve your mood and keep the workshop clean.  ccasion14:

 

[swarfrat]

Your green-balance is way off in those photos. Man - are you guys still snowed in??!?

 

[mayfly]

Your green-balance is way off in those photos. Man - are you guys still snowed in??!?

That's not snowed in.  That's what we call "a skiff of snow".  i.e. - hardly any.  It's above zero all this week so that should take care of it.

 

[mayfly]

Update - getting ready to stain the box.  While I was contemplating this I was thinking "wouldn't it be nice if there was some kind of stand that could hold it for me while I stain it?  Maybe something at a good working height..."... Then it hit me - just use a speaker stand!

 

[Logrinn]

It just goes to show: the best ideas are the simple ones!  :icon_thumright:

 

[mayfly]

First coat of stain is on.  I'm also lining the inside using self-adhesive foam left over from a HiFi project.

Yes I'm lining the brace.  Call me anal...

 

[mayfly]

I made a mistake with the stain!  It's a water based stain and I didn't seal the wood beforehand - which means the grain raised and I had to sand it all down then re-apply.  The stain ended up being a lot darker than I wanted.

I should have known better.  c'est la vie

Looks pretty good with a coat or two of clear coat though...

 

[Re-Pete]

it was a nice day, so I took it out side!  Whipped out the router and put a roundover around the outside of the box.

Nothing like working outside to improve your mood and keep the workshop clean.  ccasion14:

That white grass, we don't have that in Australia....  :icon_jokercolor:

 

[mayfly]

One other thing about that excursion limit - if you cross over the Beta 8CX at 200 Hz you can take it all the way to thermal limit (about 119db which should be plenty paint peeling for any normal use)

I'm still thinking about building my FRFR with a "sub" for use with drum/bass monitor and only take the 8CX when I just need it for guitar. I have an offlabel Eminence Delta Pro 15 - which is xmax limited, but I can get it in a reasonably flat box and take the xmax limit up to 118db @ 62 Hz, with a -3db point at 47 Hz which ought to pack decent punch for a bass and  drum monitor - at least up close. (If you're talking about using it as a stage/room filling monitor - that 118db @ 1m drops off to 104db @ 10m, which doesn't leave a ton of headroom for deep bass drum transients. If you figure you want 10db peak over the average level - it's  adequate for rehearsal with electronic drums. It doesn't really do justice to my 32" marching bass drum though)

Here's a completely different approach:  The Karlsonator

http://www.diyaudio.com/forums/full-range/239386-karlsonator.html

 

[swarfrat]

I got through about 3 pages of that without figuring out what it was other than the fact that it was some huge contraption  that didn't seem particularly suited to sound reinforcement because of its uniqueness and non-packable shape.

But it has reignited my search for a good FRFR monitor (design)  that CAN do justice to drums.

Crossing that 8CX over at 200hz, and matching it with a pair of Dayton DCS305-4 12" subs, it looks like a 14L box / 80Hz for the Beta 8CX and 163L/27Hz for the 12's, biamp at 140W for the Beta8CX and 415W for the 12's should yield a not terribly huge box that can hit 117db with a -3db of 25Hz.  So far that's looking like the best combination for me anyway of size, volume, efficiency, cost and low frequency limits.  I wasn't shooting for quite that low, but most of the high dollar PA drivers need huge boxes, or only go down to the low 50's, or cost 6db more than my budget.