looking to build dual 4x12 cabs

hachi kid · #1 06-05-2011, 03:39 PM

I'm looking at building two vertically offset 4x12 similar to the arrangement that Mesa aligns their 4x12 bass cab, but I'm wanting them a bit shorter and wider. about as tall as your usual 6x10 cab. the thing is, I'm wanting one to be sealed with guitar speakers in it for the highs, and the other to be ported with bass speakers in it for the lows. I use two different amps as well, so all the low frequencies will be trimmed off the high cab and will just be my articulation and distortion. the "bass cab" will be for the lows and thump. I'm wondering in terms of making the cab efficient and all, will I be able to make both boxes the same size? or is there a program I can use to determine what size the speakers need to be? like, if I plug in the speaker specs, be able to see how big the box needs to be. also, is it just the amount of space inside the cab that matters? or does the actual shape of the cab matter, as well? like, if it's 3 cubic feet, for instance, does it care that the 3 cubic feet is tall and skinny or short and squatty?

Tracebassplayer · #2 06-05-2011, 04:46 PM

You can make both cabs the same size and probably the 12's need less room than the 15's to tune. So, you could make "false walls" around the 12's to make the enclosure around each speaker the proper dimensions without having to make the outside cab dimensions smaller - a cab inside of a cab kinda thing, dig?

MysticMichael · #3 06-05-2011, 05:03 PM

Quote:

Originally Posted by hachi kid

also, is it just the amount of space inside the cab that matters? or does the actual shape of the cab matter, as well? like, if it's 3 cubic feet, for instance, does it care that the 3 cubic feet is tall and skinny or short and squatty?

AFAIK, the actual shape of the box matters very little, if at all, to the quality & quantity of sound that the cab emits. What matters a great deal is the overall dimensions, along with the porting & tuning of the box, as well as how well, and in what manner, it is braced and reinforced.

MM

will33 · #4 06-05-2011, 05:03 PM

WinISD Pro is what to use for modeling driver/box combinations. That's effective for predicting performance below about 200hz. It's a free download. Refer to the drivers response chart for what's going on above 200hz. A pair of guitar speakers can easily hang with 4 bass speakers.

Tracebassplayer · #5 06-05-2011, 05:23 PM

WinISD Pro is what to use for modeling driver/box combinations +1

With this you can find out how much room and porting you need for a particular speaker.

Hopefully less than what you have inside the cab.

So, if you have a cab sectioned into 4 quarters (boxes) and your 4 cab sections are 28Lx24Wx18D "boxes" (<-- dimensions of 1 Trace Elliot 1518T cab)
but, say your 12" speaker needs an enclosure 14Lx14Wx 18D...
You can add walls inside the cab to make each "box" 14x14x18... savvy?

That said.. if you had ONE cab with a 15 and a 12 in it and you stacked an identical cab above it...
15 ... 12
15 ... 12

Not only do you get the normal gain in volume from adding speakers but, you ALSO get a free 6 Db gain for the stacking of identical cabs.

If you separate them you still get the normal gain in volume but, you LOSE the free 6 db gain...

You can prove it to yourself with a Sound Meter / Decibel meter from Radio shack... try it...

JGR · #6 06-05-2011, 05:23 PM

Just get a Berg NV412-it does the highs, lows, and everything in between.

hachi kid · #7 06-05-2011, 05:48 PM

wow, thanks for all the responses guys! I actually know little about porting/tuning cabs and reinforcing them. is there a place I can read up on how to know what to I'd need to do to do these things correctly? I looked at the Berg NV412. I would actually want the cab to be that size. two of them. one ported that is meant for bass speakers. the other sealed meant for guitar speakers. I figure for bass, it should be good, but for the cab with guitar speakers, would it still sound as good?

hachi kid · #8 06-06-2011, 02:12 PM

so, I'm thinking I'm gonna be going with a 2x15 cab instead of a 4x12 cab for the lows. did some testing, and found out I like 15's better for lows than 12's. googled a bit, and found some exact schematics/plans for a Sunn 200s 2x15 cab. so, I think I'm gonna be going with that. question I have, though, is about the speakers.

since this cab is going to be pushing lows at a high volume, should I be putting more importance on high Xmax? I've found a driver I want to use (Faital Pro 15PR400 Speakers - Faital Pro 15PR400 bass guitar and PA speaker that has a lightweight neodymium magnet - Faital Pro 15PR400 800 watt high efficiency of 100dB SPL woofer for all mid-bass and bass applications. Faital Pro 15PR400 sp) because it reaches down to 35Hz and has an SPL rating of 100dB, but has a rating of 5.75mm Xmax. there's a 500 watt version though (Faital Pro 15FH500 Speakers - Faital Pro 15FH500 bass guitar speaker and subwoofer 15" speaker that has a lightweight neodymium magnet - Faital Pro 15FH500 1,000 watt 18" high efficiency of 98dB SPL woofer for all high power bass applications. Faital), that has a rating of 9.25MM Xmax, but has an SPL rating of 98dB...what I don't want at all is that farting out sound, and I know to get really good low end loudly, you want good travel. but I'm wondering if I should go for the one with the higher Xmax, and not worry about the 2dB drop in sensitivity. thoughts?

also, anyone know if someone made an offset 4x12 cab for guitar? or would it be ok to look at the outside dimensions of the Bergantino NV412, keep it sealed up, and put guitar speakers in it? the frequencies around/below 300hz will be cut.

rpsands · #9 06-06-2011, 02:28 PM

A guitar 2x12 will be as loud as a 2x15 sub cabinet easily.

hachi kid · #10 06-06-2011, 02:37 PM

I know. I'm also going for a certain look. I'd like the cabs to be close to the same outside dimension.

will33 · #11 06-06-2011, 02:38 PM

With a 215 you could do it all in one largish cab. Put the 215's one on top the other on one side of the cab and put a 10" or 12" guitar driver or 2 in a sealed subchamber in the top corner on the other side like you do dedicated mid drivers in a twoway cab. Depending on the spl/lowend output capability of the 15's one or two guitar drivers will suffice. No need for 4 of them. This could be split up into 2 cabs for ease of transport. Just make sure all like drivers are aligned vertically for good dispersion. No drivers playing the same thing put side by side. It's ok to have a guitar driver beside a 15 as they're operating in different passbands.

staindbass · #12 06-06-2011, 04:01 PM

Quote:

Originally Posted by rpsands

A guitar 2x12 will be as loud as a 2x15 sub cabinet easily.

i highly doubt that. it all depends on which speakers are in the cabinet. go to a music store and try a 2x12 versus a 2x15 and see if this man knows what he is talking about before spending any money.

billfitzmaurice · #13 06-06-2011, 04:04 PM

Quote:

Originally Posted by staindbass

see if this man knows what he is talking about before spending any money.

He does. Assuming the 2x12 is high-passed so it's not asked to do what it's not designed to do it will be at least as loud as a 2x15 bass cab, if not louder.

staindbass · #14 06-06-2011, 04:16 PM

i like what you are going for. but ported cabs are not as articulated as sealed cabs. they sound slightly muddy because the transient response is poor and the phase difference between the ports and your speakers. then when you are onstage you have 3 phasings to deal with, the speakers, the ports and the pa. its bad enough with 2. if you do a sealed cab and a ported cab, even with the same speakers you will still have some timing differences, and it wont behave as a unit. i think you should run all the speakers full range. if you use one for highs and the other for lows, your going to need more wattage to equal the output of them all running full range and you will be driving the low cab hard. if you dont want tweeters, i would say 12" is as big as you should go.

will33 · #15 06-06-2011, 04:29 PM

Running them all fullrange would entirely defeat the purpose of mixing the two different drivers. The lowend would be limited to whatever wouldn't blow the guitar drivers, the highest end would be entirely consumed by the guitar drivers and inbetween (the vast majority of your sound) would be a phasy/wishywashy/muddy mess. Stick to bass drivers for the lows crossed to guitar drivers for mids/highs.

billfitzmaurice · #16 06-06-2011, 05:33 PM

Quote:

Originally Posted by staindbass

i like what you are going for. but ported cabs are not as articulated as sealed cabs. they sound slightly muddy because the transient response is poor and the phase difference between the ports and your speakers. then when you are onstage you have 3 phasings to deal with, the speakers, the ports and the pa. its bad enough with 2. if you do a sealed cab and a ported cab, even with the same speakers you will still have some timing differences, and it wont behave as a unit. i think you should run all the speakers full range. if you use one for highs and the other for lows, your going to need more wattage to equal the output of them all running full range and you will be driving the low cab hard. .

No offense, but none of the above is true.

hachi kid · #17 06-06-2011, 05:44 PM

I think there's some confusion going on.

my bass has two outputs. I bi-amp like Billy Sheehan does. here's my signal path:

the neck humbucker goes to one output on my bass
that goes to an SWR Workingman's 4004 that is EQ'd for lows and low mids
that amplifier will go to the Sunn 200s 2x15 replica cab which will be ported and loaded with bass speakers

it will be there for the "bottom". all the thump and the clean bass tone to support a band.

my questions with this side of the rig is should I be putting more emphasis on Xmax or SPL? I'm looking at a speaker that has a 100dB SPL rating, but an Xmax rating of 5.75mm. there is a similar driver by the same manufacturer that has a 98dB SPL rating, but has an Xmax rating of 9.25mm. I'm going to be playing at loud volumes, and should I be concerning myself with the speaker that is 2dB more efficient? or the one that has almost double the Xmax rating? I will be running frequencies down to the 35-40Hz range with this cab, and at high volumes.

my p-pickup and bridge humbucker goes to a second output on the bass guitar
that goes to a Carvin X100B (100w all tube guitar amp) that is EQ'd for mids/high mid/treble/distortion. my articulation, basically
that will go to the diagonally offset 4x12 cab with guitar speakers in it.

there won't be much low frequencies going to it.

my questions with this side of the rig is would it be ok to use the outside dimensions of the Bergantino NV412, brace it, and make the box sealed, and put guitar speakers in it? the frequencies around/below 300hz will be cut. or would it sound like doodie? I have Win ISD Pro, but I'm not so sure how to use it, or what to make of the information I'm getting from it.

also, does anyone know if someone made an offset 4x12 guitar cab?