Build Guitar Bass cabinet

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Hello,

I'm a real newbie at this site. I've been surfing around on forums to learn as much as I can to build a (Guitar) bass cabinet. The more I read the more I get confused.

Any way, I am planing to build it. And I would like to ask the people with experiences to give me guidance. Here are my thougth:

1) I would use 3/4" thick Plywood
2) I will use (speaker) LEGEND CB15 - 8 Ohms, 300 Watts
this LEGEND CB15 requires only 2 cubic foots closed box.

Questions:

1) Could you provide me (closest) measurement of the cut-wood to build 2 cubic foots.
2) Do I have to make cross over within this box? (I don't even know that the cross over is).
3) what I need to included the cross-over in the box?
 
For bass guitar you do not need a crossover unless the driver specifies. A crossover is a circuit that splits up the frequencies and sends them to different types of speakers in simple terms. There are many free calculators online that will be able to calculate the box for you.
 
Hi, i played electric bass for 8 years.
The cabinet is the 80 % of sound that you want.
Generally bass cabnet work in bass reflex, and have or a single 15" or more 8 - 10 " driver.
I have a 15" rcf pro ( 800 w rms ) in a marine plywood cabinet ( bass reflex ) + a double piezoelectric tweeter. It Sound cold, deep and metallic, not for jazz or warm style.
If u want a warm & fat sound u can use 2 or 4 8" or 10 " speaker in bass reflex enclosure ( i like eminence beta 8a 225 wrms each :eek:).

What's style of sound that u want? fatty, quick or cold ,deep ....
How many power ?

Plywood imho is the better material, light, strong and sound good. Mdf is to heavy and imho have a bad sound for a bass / guitar application.
 
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2) I will use (speaker) LEGEND CB15 - 8 Ohms, 300 Watts
this LEGEND CB15 requires only 2 cubic foots closed box.

Questions:

1) Could you provide me (closest) measurement of the cut-wood to build 2 cubic foots.

this one ?

Speaker Detail | Eminence Speaker

regarding your question
if you dont know how to calculate simple box dimensions, may I ask where do the 2 cubic feet come from ?
 
Hi BuildByHands,

Here is the box data you asked for (you always need to add some volume, here I added 20%, you also want to staple about 2" of fiberfill to the inside, e.g.: one side, top and back):

Regards,
 

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  • Eminence_CB15_closed_Boxplot.jpg
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Plywood imho is the better material, light, strong and sound good. Mdf is to heavy and imho have a bad sound for a bass / guitar application.

Hi,
How do you define your "good sound" with the plywood?

I've built quite a few bass amp cabs and have always gone for MDF. I tried plywood and it's cheaper but for me is doesn't sound as good and can be difficult to work with. I found there was more flex in the cabinet with ply, which means for a more resonant sound (so louder, I guess) but the bass is much slower. The rigidity of MDF makes the transient response better, the kind of thing you really need when you're talking about 15" cones...

just my 2 cents

and BuildbyHands, the tweeter is the small driver which deals with high frequencies (something that you may not think is too important but can really bring a punch to the sound of your bass). To my experience if you use a compression driver you don't need to use a crossover, you would want to wire a small high power resistor is series with the tweeter though.
 
........

and BuildbyHands, the tweeter is the small driver which deals with high frequencies (something that you may not think is too important but can really bring a punch to the sound of your bass). To my experience if you use a compression driver you don't need to use a crossover, you would want to wire a small high power resistor is series with the tweeter though.

Oo-er. I wouldn't use a compression driver without a crossover unless you want it to cook...

With piezo tweeters (which are inherantly capacitive - they'll cross themselves over), you can get away without a crossover, though they're much better with.

Chris
 
thefamilybassman,

My cabinet is completely sealed.
Few friends told me that I have to make holes in my cabinet so the speaker won't be blown. is this correct?

Currently, my cabinet have:

1) speaker (wired to input jack)
2) input jack ( wire to speaker)

If I am to include a tweeter, how I am going to wire between the three.

Could you draw picture how to apply the high power resister to it? and what tweeter would fit 300 watts cabinet?

I really appreciate your advice.





Hi,
How do you define your "good sound" with the plywood?

I've built quite a few bass amp cabs and have always gone for MDF. I tried plywood and it's cheaper but for me is doesn't sound as good and can be difficult to work with. I found there was more flex in the cabinet with ply, which means for a more resonant sound (so louder, I guess) but the bass is much slower. The rigidity of MDF makes the transient response better, the kind of thing you really need when you're talking about 15" cones...

just my 2 cents

and BuildbyHands, the tweeter is the small driver which deals with high frequencies (something that you may not think is too important but can really bring a punch to the sound of your bass). To my experience if you use a compression driver you don't need to use a crossover, you would want to wire a small high power resistor is series with the tweeter though.
 
Last edited:
thefamilybassman,

My cabinet is completely sealed.
Few friends told me that I have to make holes in my cabinet so the speaker won't be blown. is this correct?

Could you draw picture how to apply the high power resister to it? and what tweeter would fit 300 watts cabinet?

Properly porting (holes or duct tubes) your cabinet could make it louder down low, too much power will burn the speaker or rip up the cone whether ported or sealed.

A resistor alone will not protect a tweeter, at minimum you will need a capacitor and a resistor wired in series with the tweeter, unless the tweeter is the same sensitivity as the woofer, then the resistor may be left out.

Amp+ to capacitor in, capacitor out to resistor in, resistor out to tweeter +, tweeter - to amp -.

The capacitor and resistor values are dependent on the tweeter you choose.
 
I've never heard of a sealed or ported cabinet tear up speakers. So far as I know, only certain horns can tear them, and that's down to the pressure difference across the cone.
Sealed or ported are pretty constant across the cone, so I can't see any problems here.

Chris
 
I've never heard of a sealed or ported cabinet tear up speakers. So far as I know, only certain horns can tear them, and that's down to the pressure difference across the cone.
Sealed or ported are pretty constant across the cone, so I can't see any problems here.

Chris

Over the course of years, had many speakers in monitor cabinets torn or kinked from being driven below Fb, trying to get too much kick drum with no low cut filter.

And that was in the days when they were being driven with "only" 175 watts.

It is pretty easy to exceed Xmech even with fairly low power with a bass guitar, slapping the strings can put out very high amplitude signals down to a few Hz.

A bass player friend of mine mechanically killed his JBL D-130 on the first slap, the voice coil exited the gap, and squashed itself trying to go back in.
Expensive.

I don't recall the amp for sure, but it was probably no more than 60 watts in to a sealed enclosure.

Art
 
Ah, I thought you meant actually ripping up the cone - like I said, I've only heard of that in horn enclosures.

Mechanical damage such as the stuff you've described... I can believe it.
Try slap bass into an open backed 10" combo. The driver's Xmax was 3mm (one way), and we passed that nice and quickly. Ended up at somewhere around 16mm p/p transients. The ringing notes were more like 8mm p/p. This was on less than 30w... Lurvely :D
 
All,
Thank you for all your advice.

I have searched for 300 watt 8 ohm head but could not see one. I have read some blogs and I understand that:

1) I can use amp head with 300 watt 4 ohm. But I will get only around 175 watt

2) I can use an amp head with 500 watt 4 ohm or 300 watt 8 ohm

I want to confirm if my understanding is correct. Therefore, after finish this cabinet (300 watt 8 ohm)

Can I use MarkBass III 500W? Or will it blow the speaker?

The specification is as below.
Markbass Little Mark III 500W Bass Amp Head Features:

  • 4-band EQ for precise tonal control
  • Balanced input for acoustic basses
  • Balanced DI with level control and pre/post switch
Markbass Little Mark III 500W Bass Amp Head Specifications:

  • Inputs
  • Input impedance: 500kOhm, maximum voltage 15Vpp
  • Balanced Input (XLR) impedance: 100kOhm, maximum voltage 25Vpp
  • Effect Return Impedance: 33kOhm, maximum voltage 10Vpp
  • Controls:
  • Gain: -60dB–+23 dB range
  • Master Volume
  • Line Out Level
  • Ground Lift switch on rear panel
  • Pre/Post EQ switch on rear panel
  • Equalization
  • Low: Center frequency 60Hz, level ±16dB
  • Low Mid: Center frequency 360Hz, level ±16dB
  • High Mid: Center frequency 800Hz, level ±16dB
  • High: 5kHz shelf, level ±16dB
  • VPF (Variable Pre-shape Filter): Center frequency 380Hz (cut)
  • VLE (Vintage Loudspeaker Emulator): Frequency range 250Hz–20 kHz (cut)
  • Output:
  • Line Out: Balanced XLR, maximum voltage 20Vpp
  • Effect Send: Unbalanced, maximum voltage 20Vpp (pre-EQ)
  • Tuner Out: Unbalanced, maximum voltage 2Vpp
  • Speaker Out: Speakon & 1/4" combo, 1/4"
  • Weight: 6.4 lb. (2.9kg)
  • Dimensions: 10-9/10" W x 2-4/5" H x 10-1/10" D
  • Output Power: 300W RMS @ 8 ohm, 500W RMS @ 4 ohm


Ah, I thought you meant actually ripping up the cone - like I said, I've only heard of that in horn enclosures.

Mechanical damage such as the stuff you've described... I can believe it.
Try slap bass into an open backed 10" combo. The driver's Xmax was 3mm (one way), and we passed that nice and quickly. Ended up at somewhere around 16mm p/p transients. The ringing notes were more like 8mm p/p. This was on less than 30w... Lurvely :D
 
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