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Custom DIY 2x15 cab build

#221
stiles72 said:
Maybe I missed this in the thread - but have you thought of using aluminum dust caps on the drivers, like you did in your 4x12 cabs? I think it would really set the cab off from a cosmetic perspective.
Click to expand...

i just ordered a couple of aluminum dust caps for the 3015's, but not for cosmetic reasons, since i liked what it did for the top end of my 2512 II's. it just opened up their top end 'sparkle' a little bit more.
 
#223
Joe Louvar said:
And thinking out loud - the round plastic ports seem to make building lighter and easier. Since the Starliner 215 has two 4” round ports which equals 8 inches of port area - I wonder if for example the shelf port on the Barefaced Super Fifteen is about 12 inches of port area. I think Mr Foxen has a super 15 may be I can ask him to measure the size of the shelf port and depth (length).
Click to expand...

Bad math. Area = pi * r^2 where r is the radius

One 4 in diameter port = 12.57 in^2. Two gives you 25.13 in^2.

For contrast, one 6 in diameter port gives you 28.26 in^2.

Playing around last night, with six 4" diameter ports, top, middle, bottom on each side, you could feed power in until you run into the excursion limits (~730 watts according to WinISD) and your port air velocity would still be about 62 ft/sec. That's a little above the recommended 5% of the speed of sound (~55 ft/sec), but pretty reasonable.

That 730 watts would be putting about 130 dB it seems. "Military jet aircraft take-off from aircraft carrier with afterburner at 50 ft (130 dB)." according to Invalid Link Removed. In short, probably more than you'll ever need.

KO
 
#227
Right on, John; totally bitchin' cab! Remember we had a convo a few weeks back about loading K-140's into the Hard Truckers' 2x15- you executed the idea in the realm of reasonable weight.

Don't quote me, and keep this to yourself, but I heard on the grapevine a certain hermetic cab designer was working on a design of the same sort of configuration.

Two 15's in a reasonable cab.... you could say "done". Think this cab with a Mesa 400+ (4 Mullard 12AX-7's + 12 RCA Blackface 6L6's) along with a '62 Jazz might sound good?

I dig the cab- I'm sure it gets the job done in a most righteous manner. The 2x12 idea also rocks; not a fan of single speaker designs except for very low volume apps- like practicing in the living room.

If you build some for customers, you can skip a lot of hassle regarding shipping by just going down to your local "Going Postal" store, corporate UPS. FedEx store, or what have you, and have them pack and ship it. Prolly run $150-$200, but let the customer pay for it, and let the shipper assume liability for shipping these bad boys.
 
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#229
thanks guys. i really appreciate it.


greengoblin said:
Have you considered doing a sealed clip with the amps for comparison? I, for one, would be interested in hearing the difference.
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since i have the grill off of it right now, i'll be making a couple of clips with the SVT and streamliner with and without the ports open.

i tested it with the heavy port blockers that look like this. ( i removed the wing nut, cut the 3/8" bolt down and used a 3/8" nut so they'd fit under the grill, but each of them still weighs 1/2lb!)

portblocker-01.jpg



so in case i want to go with it sealed, i made some lightweight ones, that weigh only 1 oz each, by taking a 4" pipe cap and wrapping 8 layers of self bonding rubber tape around it so make sure that tey get a perfect seal:

portblocker-02.jpg


another pic of the lightweight one:

portblocker-03.jpg



and the comparison shot:

portblocker-04.jpg



the cab is definitely ALOT more 3D with them open, and the low end seems to go thru the floor, whereas when it's sealed it's tighter and sounds more like an SVT 810 cab.
 
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#230
i just made two clips with the STM900 but the recordings don't really represent the difference that you hear when sitting in front of the cab (they both sound nearly identical so IMO, it wouldn't be much help, if any posting them). when you're playing it live with the ports open, the low end is much more pronounced and fills the room than with them blocked.
 
#234
Huge difference to me. It would make a world of difference in a live setting having or not having that lower octave "speak" that the ports are enhancing.
On a recording its the difference between the bass laying down a bottom to the sound (like a good upright or organ bass pedals) or it being situated "in the chest" rather than "in the groin". I like the tone of the chest but the feel of the groin!

Vote>

Groin
or
Chest
 
#238
rpsands said:
The cab is a bit on the small side--around 2.4cf net right? That'd probably explain most of the boom. Could also be amp or bass voicing though.
Click to expand...

IMO, the cab does have alot of low end, but i think that it's the STM900 that's accentuating it. i was running its bass tone control (which is at 55hz) at noon and i actually run it at 9-10 o'clock most of the time.
 
#239
John, thanks for posting the ported and sealed clips. Listening through fairly decent headphones I appreciate the extra roundness of the ported cab. But my ported 3015-loaded cabs (similar cab volume) can be a bit boomy depending on the room.
 

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