is this too much volume??? speaker enclosure.

[bon viesta]

my 4x12 marshall slant cabinet idea has been largely calculated, and without making this an essay long, let’s just say that with all the obstructions and all of that being factored roughly into the final results for my volume per speaker findings, i’ve finally almost reached the end. but another problem has come up, though the problem shows that i’ve made progress. at the top of the cabinet, the area with the least volume, the volume per speaker is roughly 1.16 cubic feet. at the bottom of the cabinet, the straight section, the volume per speaker is roughly 1.76. that’s quite a difference, as one would expect, but that’s not all there is to it. the speakers i’ll use are eminence beta 12a speakers, and their volume per speaker recommendation is 0.9 to 1.25 cubic feet. the top of the slant checks out for that recommendation, but the bottom is too large. is this a problem?? will the two speakers make different noises and be competing with each other? can i add volume to the bottom section of the cabinet without interfering with the top of the cabinets volume? below is an image of the cabinet interior (listing). also an image of the total cabinet volume, because that’s useful. it’s not separated from top to bottom, but i did the top and bottom calculations because they’re basically different enclosures for each set of speaker and it was important information to know. thoughts would be very appreciated!!!

 

[mmbongo]

Wait...will you have four separate chambers or one big chamber? Either way, no way you will have enough airspace for 4 12's to work properly.

 

[bon viesta]

Wait...will you have four separate chambers or one big chamber? Either way, no way you will have enough airspace for 4 12's to work properly.

one big chamber. and why not?

 

[mmbongo]

one big chamber. and why not?

If it's one big chamber the slant does not matter. It's all just one single airspace.

If you are not wanting much low end it might work okay, what are your response numbers looking like when you ran them on a speaker tuning program?

 

[bon viesta]

If it's one big chamber the slant does not matter. It's all just one single airspace.

If you are not wanting much low end it might work okay, what are your response numbers looking like when you ran them on a speaker tuning program?

i don’t have any of that stuff yet i’m afraid you’re putting too much faith in me being competent. i don’t have any speakers right now, or cabinet. i’m just a 15 year old with some money and a vision!! and also a burning desire to sort out all the problems i’m seeing with that vision. i think bass response will be adequate by my standards, not shake your guts and the entire room bassy, but it could fly in non-gigging environment. and the one big chamber news is great. does it really work that way??? i’d think that i would have to account for how the wall will be closer to those speakers so it might do some things differently sonically.

 

[Jeff Scott]

Wait...will you have four separate chambers or one big chamber? Either way, no way you will have enough airspace for 4 12's to work properly.

The first amp I used on a fairly regular basis when I began playing bass was a friend's Marshall 1987 and 4-12 cabinet. Seemed to work and sound (as I recall) just fine with the late '60s Jazz Bass I had way back in the last century.

 

[agedhorse]

How are you calculating and determining performance if you don’t understand how the basic airspace factors into those calculations?

Didn’t you already go down this road with a Fender 212, complete with time wasting mistakes?

 

[mmbongo]

i don’t have any of that stuff yet i’m afraid you’re putting too much faith in me being competent. i don’t have any speakers right now, or cabinet. i’m just a 15 year old with some money and a vision!! and also a burning desire to sort out all the problems i’m seeing with that vision. i think bass response will be adequate by my standards, not shake your guts and the entire room bassy, but it could fly in non-gigging environment. and the one big chamber news is great. does it really work that way??? i’d think that i would have to account for how the wall will be closer to those speakers so it might do some things differently sonically.

Well then, here's my honest recommendation for you.

Scrap this idea. Buy a nice 1x12 combo bass amp like an Ampeg Rocket 112. It will cost less and outperform what you are trying to do. It will also save you lots of frustration and disappointment.

You're trying to put 4 12" bass speakers in a cabinet designed for guitar speakers. Have you noticed that no bass amp companies sell such a thing? There's a reason for that

 

[agedhorse]

Ahhhh, you are young. That would have been helpful information to know up front.

At your age, it’s time to read, study, finish school, etc. You can buy a finished used cabinet for less than thrashing about with a half-baked design, and use the money you save to buy some books on the topic so that down the road you will be in a better position to be successful.

 

[Prana Ferox]

If you're not gigging you don't want a 4x12.

 

[bon viesta]

How are you calculating and determining performance if you don’t understand how the basic airspace factors into those calculations?

Didn’t you already go down this road with a Fender 212, complete with time wasting mistakes?

im not determining performance. i see eminence’s recommended enclosure volume for a 12” beta speaker, and i see if the volume of the cabinet (29x30x14(bottom)x11(top), 5/8” thickness) divided by 4, plus subtracting the volume of all the little things inside that cabinet, equal a volume within the recommended 0.9 to 1.25 cubic feet as per eminence. the fender thing was just me going “this looks big enough, they made it for bass, why can’t i use it?” and i really do thank you for your patience with me on that one. this marshall thing is more thought out, and it’s a little more reasonable (i’m assuming?).

 

[bon viesta]

wow maybe i shouldn’t have given my age i’ll also mention here that my father is an electrical engineer who makes guitar amp kits as well as the odd cabinet or two, and he also makes guitars from scratch. i believe that makes him a luthier? so i swear i’m not just a kid with a dream and a screwdriver and a wooden box. rather, i have an adult with that stuff. who knows how to use it!!!

 

[agedhorse]

That’s a good opportunity to learn, and as an engineer myself I’m sure your father would agree with my earlier comments.

 

[mmbongo]

wow maybe i shouldn’t have given my age i’ll also mention here that my father is an electrical engineer who makes guitar amp kits as well as the odd cabinet or two, and he also makes guitars from scratch. i believe that makes him a luthier? so i swear i’m not just a kid with a dream and a screwdriver and a wooden box. rather, i have an adult with that stuff. who knows how to use it!!!

When I was a little older than you...maybe around 18...this would be late 80's....I discovered car audio. I totally understand being a kid with a screwdriver and there's nothing like learning by doing. I probably built 10 speaker boxes that sounded like pure crap because I hadn't yet learned that you can't just stick a speaker in a box. I kept going with it and did car audio all through school until about 1995 and build hundreds of speaker enclosures. It was great fun and I learned something new with each enclosure.

Point being, I know exactly how you feel. So I'm torn between letting you learn the hard way why your idea won't work (heck you might love it..but I doubt it...because I've done it) and imparting my experience on you and explaining why you should just get a proper bass amp.

And you know what else? Your dad sounds a lot like my dad. We built a lot of my first speaker boxes together and he taught me a lot about carpentry. He passed away last year but I still have those memories of us together. So you do your thing. I wouldn't do it, but you couldn't tell me that when I was 15. That's how you learn.

 

[bon viesta]

That’s a good opportunity to learn, and as an engineer myself I’m sure your father would agree with my earlier comments.

i’ve been talking with him about it and he doesn’t seem so bewildered as any of you guys. i’m not just making these plans in my head, i’m coordinating. i’m also asking him questions when i have them. he thinks that the cabinet would work fine with insulation, and he doesn’t seem to be the kind to sort of make me get the low watt combo amp because i’m a teenager. i’ve been down that road!!! man that ampeg sounded like crap. it buzzed on g.

 

[Prana Ferox]

For the Beta 12A-2, Eminence recommends at least 1.75ft3 per driver and ported for bass cabs, with more volume to reach lower. A sealed application with 1ft3 per driver is going to be rolling off at 150hz and 10db down by 55, by Eminence's own charts; it's also falling off above 2khz.

If I was looking to DIY something that looked right under a tube amp and wanted to do minimal research I'd look at a Fearful 12/6 or 15/6 cube, or one of the BFM designs. A little more googling would bring up many more options. In a box this size you could just put a ported FaitalPro 15PR400 or Kappalite 3015 and spend your time on the vintage Tolex and grill cloth.

 

[bon viesta]

For the Beta 12A-2, Eminence recommends at least 1.75ft3 per driver and ported for bass cabs, with more volume to reach lower. A sealed application with 1ft3 per driver is going to be rolling off at 150hz and 10db down by 55, by Eminence's own charts; it's also falling off above 2khz.

If I was looking to DIY something that looked right under a tube amp and wanted to do minimal research I'd look at a Fearful 12/6 or 15/6 cube, or one of the BFM designs. A little more googling would bring up many more options. In a box this size you could just put a ported FaitalPro 15PR400 or Kappalite 3015 and spend your time on the vintage Tolex and grill cloth.

can you send me to where those stats are?? i’ve only been able to find this set of statistics (i found it from an eminence pdf but eminence is really slow loading for all of my devices for some reason)

 

[bon viesta]

wait… 12a-2??? that’s a different speaker. no wonder your stats look alien to me!

 

[abarson]

I've been following your threads and I'm at once happy to see a younger person looking to get involved in DIY, yet it's hard to provide guidance when many of us expect a builder/designer to have an idea of what they're doing. My first build was only moderately successful, mainly because I didn't know what to ask.

I'll echo others' responses that it's not just about putting speakers in a big enough box, it's understanding why those speakers work in that particular box. I think it's great that your dad is an EE, and I hope that maybe he can provide some guidance on your learning journey.

I'm surprised that no one has mentioned downloading a copy of WinISD to start looking at design possibilities. Others can recommend cabinet design books that might be of use as well.

I don't share your nostalgia for oversized underpowered cabinets (and I disagree with the sense of aesthetics) but I really want you to have a good learning experience and you end up with something you're proud of.

 

[bon viesta]

no wait… is it?? maybe it isn’t??