# Bass Cab build



## BoomieMCT (Dec 11, 2006)

I know this may not really belong in a HT forum but since I used the same process and tools to make this that I use to make subs and speakers I figured I'd show this off here. 

Anyway, I have a friend who plays bass in a band. He needed a bass cab for practice and small gigs but was unhappy with the extension of the equipment he had or tested out. All the easily portable bass cabs just didn't dig deep enough for him. He has a bad back and was tired of lugging his 15" cab around all the time. 

After wanting to use a HT driver (it modeled well in Unibox but he wasn't comfortable with a non-pro sound driver) I decided to use a more conventional 12" Emminance basslite driver. This is a 12" driver with good specs that only weighs 4 pounds. When it arrived I couldn't believe how light it was! 

To maximize output and extension I used a ported design. I felt a slotted port would be a bit more compact, durable, light and easy to construct then a round port. I knew slot ports needed some correction factor so I did some research and guesses of using a .8 correction factor to make up for the 1:9 height to width ratio (turns out that worked very well). The enclosure was made from 13 ply Baltic birch and covered with black carpet. Because my friend has nice wood colored guitars I stained the front with golden oak and then a few coats of poly. 

The result is a 30 pound bass cab that can dig down to the low notes on a 5 string (31 Hz) when asked to. The attack and decay is great - you can do slap bass on this if you wanted. It can go loud enough to play small venues without exertion. My friend was so happy he even stopped using his 15" when jamming at home.


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## drf (Oct 22, 2006)

Nice work. :T I am glad you didn't uses a Hifi/HT sub, even though they model well, in reality they will only last a tenth the time of a pro-driver. The transients from live guitar just kill ordinary speakers. 

i've got a thread somewhere around here about bass cabs but I can't remember were and haven't done anything about it for awhile.


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## Danny (May 3, 2006)

I've just finished building a sub box/bass cab and did a similar design to you (although the box is a trapezoid). The driver I used was based on a pro driver design so it will be fine to use as a bass cab. When I get some spare time i'll post some pics.

D.


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## BoomieMCT (Dec 11, 2006)

Danny said:


> I've just finished building a sub box/bass cab and did a similar design to you (although the box is a trapezoid). The driver I used was based on a pro driver design so it will be fine to use as a bass cab. When I get some spare time i'll post some pics.
> 
> D.


Is the box a trapezoid so you can "kick" it back? I had thought about doing that but my friend wanted a flat top to put his amp on (it just fits as is).


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## drf (Oct 22, 2006)

I have been thinking recently about guitar cabs both Bass and 6string. Also about mid/high and some 
12" P.A boxes. The original guitar amps were all made with chipboard and masonite and so forth, early bass cabs, 15" folded enclosures and many quads were also made with chipboard. Has anyone ever compared the sonics of each side by side? was sonics the main reason manufacturers swapped to ply timber or was it purely because ply lasts longer, etc, etc?


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## BoomieMCT (Dec 11, 2006)

drf said:


> Has anyone ever compared the sonics of each side by side? was sonics the main reason manufacturers swapped to ply timber or was it purely because ply lasts longer, etc, etc?


The reason I used ply was because it is light and I was trying to keep this as light as possible. I imagine that the strength and light weight of ply is why it is used now.


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## drf (Oct 22, 2006)

BoomieMCT said:


> The reason I used ply was because it is light and I was trying to keep this as light as possible. I imagine that the strength and light weight of ply is why it is used now.


You know, I didn't even think of weight as a reason. I'm going to start a general thread on cabinet materials, I am starting to doubt that chipboard is bad sonically.


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## BoomieMCT (Dec 11, 2006)

drf said:


> You know, I didn't even think of weight as a reason. I'm going to start a general thread on cabinet materials, I am starting to doubt that chipboard is bad sonically.


Yeah, in this case weight was very important.

The only thing I've heard that is bad about chipboard is that low frequencies causes it to asplode.


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## Geoff St. Germain (Dec 18, 2006)

Cool stuff! 

I've been playing bass for years and also building basses and guitars. I've pondered building a bass cabinet myself just because pretty much none of the commercial offerings in the sub $1500 range appeal to me. I play a bass with a low B (31 Hz) and I'm building one with a low F# (23 Hz) so I'm looking to design a 3-way cabinet that can hit the low notes.

I'd use plywood simply because it will better stand up to abuse than MDF. MDF in the home is fine, but in a speaker that is going to be routinely moved and can be easily dropped (I've seen my fair shares worth of guitar and bass cabs dropped) plywood is the way to go, IMO.


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## Danny (May 3, 2006)

BoomieMCT said:


> Is the box a trapezoid so you can "kick" it back? I had thought about doing that but my friend wanted a flat top to put his amp on (it just fits as is).


Mine has a flat top but the sides slope in so if you want it tilted - turn it on its side, if you want a flat top for the amp just put it horizontaly


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## BoomieMCT (Dec 11, 2006)

Geoff St. Germain said:


> I've been playing bass for years and also building basses and guitars. I've pondered building a bass cabinet myself just because pretty much none of the commercial offerings in the sub $1500 range appeal to me. I play a bass with a low B (31 Hz) and I'm building one with a low F# (23 Hz) so I'm looking to design a 3-way cabinet that can hit the low notes.


What driver are you using for your low section? I haven't found many portable pro-sound drivers that will produce an F3 at or below 23 Hz.



Geoff St. Germain said:


> I'd use plywood simply because it will better stand up to abuse than MDF. MDF in the home is fine, but in a speaker that is going to be routinely moved and can be easily dropped (I've seen my fair shares worth of guitar and bass cabs dropped) plywood is the way to go, IMO.


No doubt! I love MDF, but not for anything portable or damage prone.


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## Geoff St. Germain (Dec 18, 2006)

BoomieMCT said:


> What driver are you using for your low section? I haven't found many portable pro-sound drivers that will produce an F3 at or below 23 Hz.
> 
> 
> 
> No doubt! I love MDF, but not for anything portable or damage prone.


Yeah, I've been having some troubles as well. Right now I'm looking at the Eminence LAB12, though with it's very low sensitivity I'm going to need more than 1. A possible alternative are the upcoming PA series drivers from TC Sounds. 

One idea has been a pair of LAB12s crossed to a 10" B&C midbass crossed to a bullet tweeter or compression driver.

It certainly won't be a small cabinet, probably around the size of a 6x10" or so.


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## BoomieMCT (Dec 11, 2006)

Geoff St. Germain said:


> Yeah, I've been having some troubles as well. Right now I'm looking at the Eminence LAB12, though with it's very low sensitivity I'm going to need more than 1. A possible alternative are the upcoming PA series drivers from TC Sounds.
> 
> One idea has been a pair of LAB12s crossed to a 10" B&C midbass crossed to a bullet tweeter or compression driver.
> 
> It certainly won't be a small cabinet, probably around the size of a 6x10" or so.


That could work. Maybe a 18" in an EBS enclosure would work too? It would be bigger then two Lab12's, but it might be lighter.


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## Geoff St. Germain (Dec 18, 2006)

The thing is I have yet to find an 18" with the same LF extension as the LAB12 driver. Of course this comes at a pretty severe penalty of 89 dB/1W/1m sensitivity. I would like to find an 18" or even a 15", because each of the LAB12s weighs about the same as your typical 18" PA woofer (22 lbs), so doubling it up is obviously going to add a lot of weight.

I'm not too sure about an EBS alignment for a bass cab. I would have to say that almost all of the gigs I've played have been in venues to large to have appreciable room gain. This is based on my understanding that the EBS alignment is intended to match up with room gain to arrive at a pretty flat response.


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## Guest (Feb 28, 2008)

Is it possible for BoomieMCT to post the dimensions of the bass cab, the port etc., he built for his friend?
I am a bass player myself and need one or two of those cabs. 

Ola

Norway


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## BoomieMCT (Dec 11, 2006)

Shotgun said:


> Is it possible for BoomieMCT to post the dimensions of the bass cab, the port etc., he built for his friend?
> I am a bass player myself and need one or two of those cabs.
> 
> Ola
> ...


You know so much of what I do is on napkins so I don't save as much as I should. That being said I do happen to have the cut layout (see attached, all numbers are inches). I think the volume is 1.6 cubic feet with a 46Hz tune (equivalent to a 4.7 inch diameter port 7.8 inches long).


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## Ricci (May 23, 2007)

Geoff St. Germain said:


> The thing is I have yet to find an 18" with the same LF extension as the LAB12 driver. Of course this comes at a pretty severe penalty of 89 dB/1W/1m sensitivity. I would like to find an 18" or even a 15", because each of the LAB12s weighs about the same as your typical 18" PA woofer (22 lbs), so doubling it up is obviously going to add a lot of weight.
> 
> I'm not too sure about an EBS alignment for a bass cab. I would have to say that almost all of the gigs I've played have been in venues to large to have appreciable room gain. This is based on my understanding that the EBS alignment is intended to match up with room gain to arrive at a pretty flat response.


I've been looking at the B&C TBX100 18 with one of the bass players I gig with for use in a possible custom bass cab. The cab would need to be kind of large, maybe 27Wx25Dx30H or in the neighborhood of 8.5-9cu ft for a 25hz tune, which was what we were looking at. He's currently runnuing through an Ampeg 8x10 so that size doesn't really bother him. If you tuned higher you can decrease the cab size a lot.


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## Guest (Feb 28, 2008)

Thank you so much for your answer, BoomieMCT!!
You`re the man!

Ola


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## Geoff St. Germain (Dec 18, 2006)

Ricci said:


> I've been looking at the B&C TBX100 18 with one of the bass players I gig with for use in a possible custom bass cab. The cab would need to be kind of large, maybe 27Wx25Dx30H or in the neighborhood of 8.5-9cu ft for a 25hz tune, which was what we were looking at. He's currently runnuing through an Ampeg 8x10 so that size doesn't really bother him. If you tuned higher you can decrease the cab size a lot.


Yeah, at this point I'm looking at a 21" B&C. I'm looking at a mid/high cab with either two 10s or 12s and a compression driver. Probably a WCW setup.


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## Ricci (May 23, 2007)

What's that 21" B&C model like? I assume you would still be venting. Wouldn't it want a very large box for 25-30hz tuning?


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## Geoff St. Germain (Dec 18, 2006)

It will be vented. It is a rather large box, I'm looking at 9 cu ft tuned to 27 Hz with a high-pass around 23 Hz. I'm looking to crossover at around 100 Hz to the 10s or 12s. I'm exploring the idea of using a pair of AE Lambdas with a B&C CXT coaxial in the mid/high cab.


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## Guest (May 23, 2008)

There is some confusion here on my part regarding building BoomieMCT bass cab.
13-ply is 3/4," which means 19 mm. But in reality, is 13-ply the same as 19 mm?
Here in Norway I can only find 18 mm ply.

Ola


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## BoomieMCT (Dec 11, 2006)

Shotgun said:


> There is some confusion here on my part regarding building BoomieMCT bass cab.
> 13-ply is 3/4," which means 19 mm. But in reality, is 13-ply the same as 19 mm?
> Here in Norway I can only find 18 mm ply.
> 
> Ola


1mm shouldn't change it in any way that could be detected. I imagine you could use any kind of ply you wanted from marine grade to sandeply. Just use the one that has the properties you want. Or, in short, if you can find 18mm baltic birch then you should be fine.


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