The ROCK DESTRUCTION continues! Meet "General Sherman" (JGR's ported 1810)

[JGR]

I decided to come up with a single 4 ohm cab solution - something that could take the brunt of my QSC PLX3602 in bridged mono. There are some cool 18's out there - great sensitivity, massive power handling, huge X max (1400cc's of displacement!!! - that's big block torque!). I went with a 10 for the top end crunch this time because there is a wider selection of drivers to choose from, and it allowed me cross over a bit lower which gives me the lovely grind all down through the midrange.

Built with rabbet and dado, 1/2 shell, 3/4 baffle, lots of bracing and reinforcement around things like the wheels and handle attachment points.

Per the model, this cab is -3dB at ~ 43 Hz, max SPL of ~130dB from around 55Hz on up, and is excursion limited to 2500 watts at ~40 Hz. Plenty of thermal rating so I shouldn't smoke anything. It's a pretty powerful single cab solution, and I'm calling it General Sherman.

I'm just breaking it in, but it handles everything without flinching, and can go louder than my comfort level which is pretty freakin' loud. Weighs around 75 lbs - I put a leather handle on top, and with the cab height/handle location, it's extremely easy to tilt and roll. Dimensions are 32x24x15.

The 18 isn't slow or muddy, and I can easily cop the same vibe/punch as my sealed 15/8's, but can produce way more low end if I want it. I need Fuzzbass to come up with his active 5'ers and really see what it can do. My passive 4 strings aren't going to really stress or push it, and both of my preamps hold the low end together even if you goose the bass.

Here's a quick demo - I popped the 15A breaker on my Monster Power 3500 at the end of the video - need to remember to plug into the 20A wall circuit when running bridged! There was a lot of stuff shaking in the room, but anything you might here is stuff in the room, not the cab or speakers.

http://youtu.be/-VR0QfLFU9g

Here's the impedance sweep (nice and flat, no real areas below 4 ohm which is a good thing when running bridged)


Front:


Rear:

[KJung]

Holy Moly! That is pretty cool. Must sound massive! I bet that 10" driver crossed over low really sounds nice up top.

Impressive!

Edit: Just listened to the clip with phones. The top end DOES sound good. VERY nice!

[Bmorefoozler]

wow... i LIKE IT A LOT.

[tgriley62]

I just envy the *&^% out you guys that can do any woodworking & electronic stuff. It looks like even the head its running off of is homemade.

[tombowlus]

Once again, nice job!

[rpsands]

Port is way too small. Your realistic limitation is going to be the port. No way you could possibly get 2500 watts going through that thing--lucky if it takes 500 before it starts chuffing.

* Check out the port air speed chart.

** It does sound very nice

[JGR]

I've got a bit over 56 in^2 of port area. There isn't any chuffing, even running bass cranked at full throttle/full volume on the power amp.

[rpsands]

Originally Posted by JGR

I've got a bit over 56 in^2 of port area. There isn't any chuffing, even running bass cranked at full throttle/full volume on the power amp.

That's awesome. I think it was a trick of the angle when eyeballing the port, but I'd estimated closer to 45-ish.

Even so, with a 5-string bass there're a lot of times where you'd be approaching 20-25m/s even without any bass boost, just at 1000 watts. In my experience that's around where you start getting some weirdness/noise.

If you want to get 2500 watts realistically with 5-string I'd suggest you beef up a half inch or so of port height. Maybe an inch if you could.

[Hactar]

That looks and sounds excellent. Nice job!

[3rdcurve]

Awesome job!

[will33]

Well, once again JGR....#$@*+(%$ cool stuff. Your methodical, calculating perfectionism once again says, once you show this stuff to anyone, it's already a winner.

[rogypop]

impressive! is that eminence impero? you must have
crossed it quite low! i was planing to make 18/10 cab
but with sigma pro 18 as it seems to be one of the rare 18s
which could live up to 800 hz without major dips and peaks,
while having enough sensitivity.

[JGR]

Thanks folks!

The box came together fine but the hardware has been giving me fits - stupid stuff - I was initially using the screws that came with the side handles but they were made of cheap pot metal and snapped off when loosening/tightening like nobody's business. Ended up drilling out a bunch of them and then filling all the holes and starting over with new screws. Initially put the top handle off center - must have been tired. One of the casters' metal frames cracked... just silly stuff that fights you. All easy but time consuming fixes - plenty of sausage making behind the scenes!

I like the 10 I initially went with, but I have two more coming just to try out for good measure. Can't afford to sink much more money into it at this point as the 18 is hella expensive, but luckily it's turned out as planned, and should be able to handle the coffee house gigs.

[will33]

Ask any welder.....good quality metal, if you can afford it, is getting harder and harder to come by these days. Little consumer hardware like that gets really cheaped out on. Just try and find a screw bit for your screw gun and some screws that won't round out without going to a specialty store and spending a lot. Good stuff used to be expected and available anywhere.....nowdays, it's like a specialty item or somethin'.

Good on you for sticking to it and finding quality. Too many places nowdays sell crap and people have come to expect crap as "just the
way it is".

[bb03]

Originally Posted by rpsands

I think it was a trick of the angle when eyeballing the port...

We're all so used to seeing that speaker layout from looking at fEARfuls...it's hard to wrap the brain around the bigger scale of the 18''.

[JGR]

Originally Posted by rpsands

That's awesome. I think it was a trick of the angle when eyeballing the port, but I'd estimated closer to 45-ish.

Even so, with a 5-string bass there're a lot of times where you'd be approaching 20-25m/s even without any bass boost, just at 1000 watts. In my experience that's around where you start getting some weirdness/noise.

If you want to get 2500 watts realistically with 5-string I'd suggest you beef up a half inch or so of port height. Maybe an inch if you could.

I only play 4 bangers and thats a heck of a lot of power around the fundamental, so I don't anticipate it being a problem. The sim shows a peak of ~24 m/s at ~40-45 Hz with about 1300 watts input, and it hits around 34m/s in the same range at 2500 watts. But if I was putting in 2500 watts at the fundamental, I'd likely be way exceeding power limitations at the 60 or 80Hz overtones.

With the current port area, at 60 Hz and 2500 watts input, the port velocity is ~20 m/s, and ~10 m/s at 80Hz. If it can handle max power at the 1st octave overtones of a four or five string, I'm not sure any more port area is needed to take advantage of max power limitations based on how the whole power density equation works out.

I'll continue to hammer it, and I'll have Ken put it through it's paces with his active 5'ers the next time he's up this way.

[JGR]

Originally Posted by bb03

We're all so used to seeing that speaker layout from looking at fEARfuls...it's hard to wrap the brain around the bigger scale of the 18''.

Good point. Here's another crooked shot from more straight on - full size P next to it for reference. The 18 makes the 10 look tiny!

[WingKL]

Cool. Let's hope they aren't as prone to catching on fire when hit like General Sherman's other namesake.

[BassmanPaul]

Jonathan, you have all together too much time on your hands and my sincere respect!

[Arial Bender]

As a carpenter, when I did door hardware I used wax on the screws to decrease breakage.