2X18 Bass Guitar Cabinet Help

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Hello, I am new to this but I am attempting to make a 2x18 subwoofer cabinet that I can use for my guitar. I am going to use eminence sigma pro 18a-2 speakers.
power rating: 650watts rms; 1300watts music program
resonance frequency (fs): 28Hz
usable frequency range: 41Hz-2.4kHz
mechanical Q (qms): 8.28
Electromagnetic Q (qes): .30
Total Q (qts): .29
Compliance equivalent volume(Vas): 441.2 liters
peak diaphragm displacment: 695cc
Maximum linear excursion(Xmax): 6.1mm

I play alot of music that I want deep, booming, massive, loud, clear, Bass.
I have used a few online calculator for the enclosure and and came up with...
Height: 28.5 in.
Width: 46.1 in.
Depth: 17.6 in.
This makes the total volume of the enclosure 379.8 liters or 13.4 Ft cubed. the recommended enclosure volume is 3.3-7.5cu. ft for one so im guessing 6.6-15 cu ft. for 2?

My biggest trouble is tuning the ports. I have heard that the best balance between SPL (getting loud as possible) and SQ (sound quality) is about 32Hz so here are a few calcuation a i came upon on the web and said the minimum port diameter size should be 8.73 in. which seems a little big to me.....
but if i tried two 6inch ports the vent legths would have to be 6.71 in. in length. why is it the less quantity of ports & smaller diameter ports need to be shorter?

my questions are...
what kind of porst should i use?
how should I brace the inside for stability?
Will I need high pass or low pass filters? or crossovers?
should I have a fabric on the inside?
should i make the box the maximum manufacture recomended }volume(15 cu. ft.) to increase deepness?
should i consider bandpass?

i am looking for rediculously deep, clear, loud, massive booming bass, for reggae, hip-hop, rock music. any help or recomendations would be greatly appriciated. thank you.
 
my neighbor loves his 4x10" ampeg. It goes deep and doesn't "fart out" as he says. It goes deeper than his ampeg 6x10" but the 6x10" gets louder (used in a larger room). His 4x10" box is tuned to 50hz if I remember.

This is more a question for the diy bass player forums.
Those guys do this stuff and try lots of drivers / boxes.

Norman
 
Think I'd try modelling the driver in winISD.
420L tuned to 40Hz does well (127dB@1m, both drivers at Xmax), though it's a pretty big box.
What's the lowest tuning this cabinet is likely to see?
For a E-standard tuned 4 string, you don't need to go below 40Hz.
Drop C# requires ~35Hz. I'd expect B to be around 31Hz, so if you're using a 5-string, that'd be the target.

The lower you want it to go, the bigger the cabinet will need to be. Also, you lose a little SPL the lower you go.

How much power is available to you?
 
the cabinet can be tuned down to 29Hz. but a program I used online showed 35Hz. I think It depends on what size I adjust the ports to? I have heard that an 8 inch port is ideal for 18 inch drivers, but dosnt semm right to me. some of the online port calculators seem kinda wack.

I dont have have a power amp right now but am planning on buying one soon.

what kind of power amp would i need to get max potental out of this? together 1300 rms watts 2600 peak watts. @ 8ohms.

so maybe a QSC RMX 2450: Stereo: 500W @ 8 ohms, 750W @ 4 ohms, and 1,200W @ 2 ohms. Bridge mono: 1,500W @ 8 ohms, 2,400W @ 4 ohms?

or Crown XLS 2500: 1550W, Stereo, 2 Ohms (per ch.); 775W, Stereo, 4 Ohms (per ch.); 440W, Stereo, 8 Ohms (per ch.); 1550W, Bridge-Mono, 8 Ohms; 2400W, Bridge-Mono, 4 Ohms?
 
FYI:

b:)
 

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I am attempting to make a 2x18 subwoofer cabinet
i am looking for rediculously deep, clear, loud, massive booming bass, for reggae, hip-hop, rock music. any help or recomendations would be greatly appriciated. thank you.
You will be the nightmare of every sound-man.

There is a reason, why most bass-players today use 4x10 cabinets.
On stage you have to hear, what you are playing. Too much LF below 100 Hz does more harm then good.
 
Freak what you heard!

32Hz is not a magic number, and 8" ports are also not magic. Go download yourself a copy of WinISD Beta and model the response of various sizes boxes and ports. It is one of the better FREE calculators available that runs on a modern computer, and you can change the setup to see what trade-offs you will make to get what result.

The free "calculators" you will find online range from decent-but-limited to plain nonfunctional. Give WinISD a try.
 
you'll probably lose definition if above 6cubic foot/driver - here's Eminence 18"s in 6.2 and 8.4 cubic foot RJ-vented reflex with fb around 32 and 28. For 18 I might pick a Karlson coupler made of one sheet of plywood for bass and settle for flat to ~55Hz outdoors - but it would take two cabinets. How much lows did Ray Brown have in his bass viola?
An externally hosted image should be here but it was not working when we last tested it.
 
Stage sound under 80Hz is muddy. If you are playing relatively large venues using this as the only bass amplification, I can see the point for sound levels at 40Hz. But otherwise, your chiropractor is going to get rich. Tony Gee has a nice setup that may be better suited for this?

Humble Homemade Hifi

Separate the two and it will be more user friendly. Also, with 2x18, you'll want some sort of HF driver to give you some pop/higher harmonics. I like two separate 15's, but still want to add some HF. But, I'm more jazz/blues than DnB or metal.
 
You will be the nightmare of every sound-man.

There is a reason, why most bass-players today use 4x10 cabinets.
On stage you have to hear, what you are playing. Too much LF below 100 Hz does more harm then good.


why do you say it would do more harm then good?

isent the low E string 41Hz ? it might be i have heard that the the hightest note on a bass (24th fret g string) wont go much past 2 kHz?? so to be safe isnt the range i want to be in is 35Hz to 2.5kHz ?? I would just use this for low ends and add a 4x10. or couldnt I use this 2x18 cab for the P.A. ?
 
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Joined 2005
the thick low E string is not the most 'accurate', thus needs a more tight and accurate speaker, to avoid blurred notes
it may be so bad you cant hear if you play one note or another
and what worse is, your band members cant hear what you play either, and makes it harder for them too
 
the thick low E string is not the most 'accurate', thus needs a more tight and accurate speaker, to avoid blurred notes
it may be so bad you cant hear if you play one note or another
and what worse is, because your band members cant hear what you play either, it makes it harder for them too


good point. you always see pros with the 8x10 ampeg stacks. I figure if you mix a 4x10 with a 18" or two would give you some nice deep and clear loud bass. the 18" might be sloppy and not as tight, but how else are you gonna get super deep lows? what if i want to play music through the cab or have a keyboard or synth go through it?
 
For an instrument application???? That's playing with fire. For both the loudspeakers and the amp.

The amplifiers listed are rated into 2 ohms.

If he wants the most power available, bridged 4 ohm use will get there.
I know it may well be putting the amplifier under a lot of stress, but I honestly don't think it'd be run to full power any way - 2400w @4ohm bridged from the QSC amplifier will be more than enough: the amplifier will have clean headroom long after the speakers.
 
Looking at those, parallel the drivers to give 4 ohm, then bridge the amplifier.

You never said - what sort of bass or tuning will it see?

You needn't make it go to 29Hz if it'll never need to go past 40...



i use a 4 string now, and sometimes drop to D. who knows i might use a 5 string in the future so I would like it to be able to reach that far if i could.

But, I think that by using 2 18" and tuning that low with using a 4 string the majority of the time, i will probly come accross alot of gain and make the sound "muddy" and sloppy...... any thoughts?
 
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