Super compact, sealed 12" cab design thoughts...

[jimcroisdale]

Beer. That is my motivation.

I'm in an all originals band now, and invariably, the places we play have a full inhouse PA. I either get miked up, or the take a DI from my amp and (hopefully) run it through a cab sim, or at least a lowpass filter.

I just don't need all the power of my Genz Benz 212t any more, and it's a pain to lug about, especially knowing that it's overkill now. Smaller cab = taxi or bus instead of driving, which means I can drink beer. I like beer.

So I'm thinking of a super small cab that will do for an onstage monitor and something to mike up, powered by my Streamliner. Here's what I THINK I know so far...
[list]
[*]I understand that sealed cabs can be made much smaller than ported cabs, right?
[*]I know that a sealed cab will have a more 'natural' sound and a more gentle rolloff in the low end, right?
[*]I'm assuming that this will give the sound guy something good to work with, and he can add the big low end back on the desk eq, right?
[*]The maths are a LOT simpler...
[/list]

So, with these things in mind I'm looking to build a cab for myself.

Questions? What driver? Kappalite 3012HO? Deltalite II? Basslite? Others? (I don't need a tweeter) What size is realistic? Would 16" x 16" x 12" be a doable, or ultimately would I end up with something that's light, portable and useless? How small can I go?

I welcome your thoughts. :-)

Jim

[sifi2112]

I built a sealed 110 using an Eminence Alpha a few years ago & it was quite nice (for home practice) but couldn't take much power. I'm sure I've read on TB that the Alpha or Beta 12A might be an ok driver for this app.

[jimcroisdale]

Wanting to stay with a neo driver if I can :-)

Edited April 27, 2015 by jimcroisdale

[Beer of the Bass]

I've read that the EBP value is a rough indicator of suitability for a sealed cab (if it's not quoted in the datasheet, it's Fs divided by Qes). For sealed cabs you want an EBP value of not more than 100, ideally less. That rules out the 3012HO, though the Deltalite or Basslite might be OK depending on cab size. You'd only add around an extra kilo of weight by going for a ceramic driver like the Beta, which might not be enough to be a deal-breaker in a 1x12".

[alexclaber]

[quote name='jimcroisdale' timestamp='1430121678' post='2758036']
[list]
[*]I understand that sealed cabs can be made much smaller than ported cabs, right?
[*]I know that a sealed cab will have a more 'natural' sound and a more gentle rolloff in the low end, right?
[*]I'm assuming that this will give the sound guy something good to work with, and he can add the big low end back on the desk eq, right?
[*]The maths are a LOT simpler...
[/list]
[/quote]

Point 4 is definitely right! The first two, not really, the third, well it depends.

[charic]

[quote name='jimcroisdale' timestamp='1430121678' post='2758036']
I'm assuming that this will give the sound guy something good to work with, and he can add the big low end back on the desk eq, right?
[/quote]

A sound engineer is going to struggle to add in bass if it's not there originally, just something worth thinking about

[jimcroisdale]

The bass will be there, just attenuated as it won't be getting any help down low from the cab. It is my understanding that the bass from a sealed cab does actually go lower, albeit at a slope?

[alexclaber]

[quote name='jimcroisdale' timestamp='1430127267' post='2758113']It is my understanding that the bass from a sealed cab does actually go lower, albeit at a slope?[/quote]

Although it often does in theory (based on 1W tests), in practice it doesn't because drivers in sealed cabs run out of low frequency power handling much sooner without a port to help move air.

[jimcroisdale]

Is it fair to say that even a small cab (16x16x12in) would be better with a port then, given the use of an Eminence neo such as the Kappa/Delta/Basslite?

[SubsonicSimpleton]

Might be worth a look at this

http://personalpages.tds.net/~fdeck/bass/smallbox.pdf

[Beer of the Bass]

I've just remembered, Talkbass regular Francis Deck documented his design for a small bass cab using the Deltalite a few years ago. It was a small box design, tuned low to get the same gentle bass roll-off associated with sealed designs, and he has dimensioned drawings so it wouldn't be difficult to recreate. I haven't tried this design myself, but it might not be a bad starting point if you don't want to get more deeply into design stuff.
[url="http://personalpages.tds.net/~fdeck/bass/#projects"]http://personalpages.../bass/#projects[/url]

Edit; It's the same link Subsonic Simpleton just posted!

Edited April 27, 2015 by Beer of the Bass

[Bill Fitzmaurice]

[quote name='jimcroisdale' timestamp='1430131211' post='2758164']
Is it fair to say that even a small cab (16x16x12in) would be better with a port then, given the use of an Eminence neo such as the Kappa/Delta/Basslite?
[/quote]Have you software modeled both options? That's the first step in the design process. To be blunt, if you don't know how to use modeling software you can't design a speaker with any better result than you can playing darts while blindfolded. Through sheer luck you may make the occasional bullseye, but more often than not you'll do well to even hit the board at all.

[jimcroisdale]

It's been a couple of years since I used Win ISD, but I have been having a look in the last hour or so, yes. :-)

[JTUK]

I think your thinking is ok but driven by the wrong compromise...
You want to travel light so you can use public transport, so you can....

The problem is the variables... and the biggest is that you will sacrifice
the bass to the P.A spec..which will vary from gig to gig.
I wouldn't go down the bass monitor route unless you knew what could be
monitored and I never get the thinking that you will be ok because YOU can hear
yourself... What is the rest of the band playing to 30 ft away..??
So, unless you know the P.A and what it can produce...and the other variable
is what the engr provides, or is willing to provide and how long you get to
arrange that, you are not going to be in with much of a chance if you just take care
of your end for your own purposes.
I think you can streamline kit if you know the kit and how it works... but if you are turning
up and making it up as you go along..as the engr is late, half his wedges are down, he
isn't very good...it isn't even his rig..etc etc etc the first thing I would be thinking
is why would you go for that..??

But..if you can say you are 100% happy with the sound you get at these events, then
you are lucky..
Having said all that..which you probably don't want to hear... just make a small box as
small as you want and throw a speaker in.. and bobs your uncle.

[bigjohn]

You could think about a microhead and a cab on wheels. Or something like a Barefaced Super Compact?

I've used public transport (buses) with a couple of set ups. Once with a Barefaced Big One and amp and two basses, though that took two of us, with one bass it wouldn't have been impossible on my own. I've also caught the bus a few times with a bass and my Ampeg B100R which isn't light, but it's doable. There are other combos that are lighter and more powerful.

It doesn't matter how small and light something is if it doesn't do it's job well. You need efficiency for that in a small cab and that's a lot complicated than chucking a speaker in a box.

[Bill Fitzmaurice]

[quote name='jimcroisdale' timestamp='1430142810' post='2758337']
It's been a couple of years since I used Win ISD, but I have been having a look in the last hour or so, yes. :-)
[/quote]When you model you need to consider not just the sensitivity charts but also the Maximum SPL chart. That's actually more important than sensitivity, as it considers sensitivity, thermal and displacement limited power handling. In the vast majority of cases you'll find ported to be superior to sealed cabs.

[Phil Starr]

[quote name='jimcroisdale' timestamp='1430121678' post='2758036']


So I'm thinking of a super small cab that will do for an onstage monitor and something to mike up, powered by my Streamliner. Here's what I THINK I know so far...[list]
[*]I understand that sealed cabs can be made much smaller than ported cabs, right?
[*]I know that a sealed cab will have a more 'natural' sound and a more gentle rolloff in the low end, right?
[*]I'm assuming that this will give the sound guy something good to work with, and he can add the big low end back on the desk eq, right?
[*]The maths are a LOT simpler...
[/list]

So, with these things in mind I'm looking to build a cab for myself.

Questions? What driver? Kappalite 3012HO? Deltalite II? Basslite? Others? (I don't need a tweeter) What size is realistic? Would 16" x 16" x 12" be a doable, or ultimately would I end up with something that's light, portable and useless? How small can I go?

I welcome your thoughts. :-)

Jim
[/quote]

I think the experts are being overly pessimistic. If you want to build a cab and are happy to settle for a less than optimum sound then designing and building a successful sealed cab is easier.

What is right is that using winISD or any of the online programs to do the calculations for you will help you tweak your sound and just putting a speaker into a small box won't get the best out of the speaker. If you decide on a speaker someone here will suggest a cab size for you, if you go for an Eminence then there is helpful information on their published spec sheets and more on their website. Celestion are helpful and i think Fane have similar information to Eminence.
[list]
[*]I understand that sealed cabs can be made much smaller than ported cabs, right?
[/list]
Not always but for many speakers this is true[list]
[*]I know that a sealed cab will have a more 'natural' sound and a more gentle rolloff in the low end, right?
[/list]
What is a 'natural' sound? The roll off from a 'typical' sealed cab is 12dB/octave and 24dB/octave for a typical ported cab. EQ for the slower roll off is likely to be effective but you can't eq your onstage cab much because it will run out of excursion sooner if it is sealed.[list]
[*]I'm assuming that this will give the sound guy something good to work with, and he can add the big low end back on the desk eq, right?
[/list]
It won't make a heap of difference to the sound engineer, none at all if you are DI'ing. I've played a few times with a small monitor with the bass rolled off and the deep Bass added through the PA. I really like it, you hear the deeps from the PA anyway and it clears up the stage sound, I need to hear the rest of the band more than myself most of the time. The guitarists and singer preferred the stage sound the drummer hated it.[list]
[*]The maths are a LOT simpler...
[/list]
Well you only have to calculate the cab volume, not the port dimensions. If you use a computer program then it calculates everything for you. If you are using formulae and a calculator then I guess this is true. The build is simpler though.

The thing is that not all speakers are designed to work in sealed cabs, most bass speakers aren't so you are into looking at general purpose speakers.

The critical parameter for sealed cabs is the damping, Over damped speakers will lack bass output and roll off from a high frequency, under damped speakers allow the cone to flap around giving a bloated bass output above 100Hz, Damping or Q needs to be between 0.7 (slightly larger cab, flattest response) and 1.1 (smaller cab, small but acceptable upper bass hump). The overall damping depends upon the damping built into the speaker and the damping provided by the cab. If the speaker is well damped already, usually because it has a big powerful magnet then the extra damping of the cab will mean the cab is overdamped and you will only get a very weak bass response.

Look at speakers which are less well damped Qts> 0.38 as a quick way of identifying suitable candidates. Or use EBP as advised above.

If you want an easier program than winISD then http://www.ajdesigner.com/speaker/ will do simple calculations for you with less information needing to be fed in. It won't let you do anything sophisticated though, just the classic TS designs. It's good enough for a basic sealed box though.

[ebenezer]

I find myself with an aguilar 12 driver(from the db/gs 112)..and I am tempted
to have built a tc rs 112 copy...stick it in and hope for the best!!
I realise that driver is more of a low frequency driver and no idea of the
xmax of tc driver....here, compact rules!