Scrap heap bass cab build

[Rafael]

While it is nice to sit around and take a dream of how a cabinet should perform and then pick drivers and cabinet design to try to come as close to your ideal as possible, a lot of times external factors come into play that limit design choices for us, and one of the most restrictive is that of cobbling together something from what is available and trying to optimize those components.

Last year before the run-up in prices for neodymium put those drivers out of many people's reach I lucked out and bought five of them....yup, five. I couldn't ever get enough all at once to buy my goal of four at once so I picked them up piecemeal, and one I purchased off ebay was an odd ball driver that I never could find a match for, so after building my home brew 410 from an old PA cab I was left with this one lonely driver gathering dust in a corner.

Then I ran across an old speaker cab that looked to be about right for a 110 cab that I could use, along with my BX500, as a cab for playing acoustic gigs. I had been dragging around a Behringer cube combo with 120watts and a Bugera 12" speaker in it but that thing weighed like a million pounds.

Plugging the driver data into winisd comes up with a recommendation of just under 1 cubic foot for the cab, and unfortunately my cab is only .77 cube, but like I said, it's what I have. I hope I got the parameters right here. Here are some pics from WinIsd:





The blue trace is what WinIsd came up with on its own....about 1ft tuned to 40Hz. The other three are with my .77cube plugged in, the gray one tuned to near 40, the pink tuned to 70 which seems to give the maximum flatness to 80Hz, the second harmonic of low E, and the yellow tuned to 60Hz which gives the flattest response overall.

First off, any suggestions as to which you might find to be the best configuration? If I'm looking at flat response, it seems the 60Hz is best, but if I look at the max SPL it seems that, given my cab size, with EQ the gray line shows more potential for the fundamental, and in an acoustic situation would 104dB be plenty?

[Rafael]

Bump?

[b-b-b-bass]

I'd go with the light blue line, as it provides the most decibels at the lowest frequencies of interest (~41 Hz Low E on a 4-string, or ~30 Hz Low B on a 5-string), and a smooth rolloff that matches well to standard EQ compensation from the amp.

That Eminence S2012 is a capable little monster... my favorite 12", even at the current $140 Parts Express price. It prefers a bigger cab, to really shine.

[Rafael]

Thanks b-b-b-bass, unfortunately the blue line is the ONE configuration that I CAN'T do since it requires as larger cab than I am using! I'm trying to figure out which of the "compromise" designs is best. Oh and also the driver is a S2010, not a S2012.

[will33]

I'd use the 46 tuning or try 50. See where it unloads below,the tuning freq. at 60-70, may be too high to take any power. Keep a lower tuning and model a 3-4 db bass boost at whatever freq. the bass knob is set to on your amp and see what happens. Cool looking cab BTW.

[Rafael]

Sometimes too much information is bad: I just ran the winisd with this driver to see what the optimum [-3dB extended bass shelf] box would be and it gave me 2.36 cube box with decent response down to 40Hz.....now I don't know if I should scrap plans to put this driver in that little cab or go for a new build to the 2.36 volume.....I do have a paper coned Harke 10", maybe I should stuff THAT into the little box....too many options!

[rpsands]

The basslite is fine in that little box. If you're only using a 4-string I'd not hesitate to just tune it to 60-70hz and give it a shot. The high tuning in a small box is workable with certain types of drivers (that don't get all midbass humpy from small boxes).

It'll depend heavily on your bass and playing style whether you have enough fundamental content to cause unloading. Playing back toward the bridge will severely limit the fundamental. Using the bridge pup will affect this too.

[billfitzmaurice]

The 60 Hz tuning is the best of those you've tried. 50 to 55 Hz may be a bit better.

[DukeLeJeune]

Originally Posted by billfitzmaurice

The 60 Hz tuning is the best of those you've tried. 50 to 55 Hz may be a bit better.

Yup, I was thinking mid 50's ballpark.

Raphael, the limiting factor will probably be fartout, which is why you don't want to tune too high. You can tune a bit lower than "optimium", like Bill suggested, and then dial in a bit of bass boost if needed, and that way you end up with more useable output before fartout than if you'd used the higher tuning that gives a better-looking curve.

[Rafael]

I'm amazed at how small a change in the port length effects the tuning frequency....also I can't really use a 4" port as winisd suggests, and plugging in a 2" port gives a reasonable length but I suppose will result in some chuffing, but due to the constraints of the cab size I'm going to have to put the port on the rear which should mean you won't hear it?

[will33]

Port location doesn't matter, those freqiencies are omnidirectional. If it,is in the back, put it along an edge or in a corner. Directly behind the cone and some mids can "escape" and not get reflected back out front. Can try a 3" or a pair of 2", just watch the air velocity. Can put an elbow in it to get enough length, just make sure to subtract the space the port takes up from the overall cab volume. There's a point of no return there with small cabs and lower tunings.

[will33]

If you happen to hit that point of no return, try it with the tuning as low as you can get it, then try it sealed, pick which one sounds best. It's a 110, it's not gonna be loud, just focus on getting a nice tone out of it. Don't need a lot of power handling/output for acoustic gigs.

My .02

[MuzikMan]

It can be tricky to get the ports right in small cabs. Don't forget to subtract the port volume from your cab's net volume.

[b-b-b-bass]

Originally Posted by Rafael

... Oh and also the driver is a S2010, not a S2012.

Ooops... a minor but important detail! I've got 12" speakers on my mind. 10"s are just so 'first decade of the second millenium'. 12 is the new 10!