DIY Budget Cab! How Bad Could It Be?

[agedhorse]

There are a few very specialized, very low frequency cabinets, but they are rare and very expensive. Their purpose is to extend sub response below 30-35Hz. They are not very efficient either.

 

[Rick James]

Without knowing the parameters of those speakers, your best bet is a downsized version of what they came from.

Not necessarily. Do a little modeling with WinISD and you'll find that most cabs are smaller than ideal for the driver. It's a classic example of marketing trumping engineering, and what people want to buy is small cabs. Even if it's a 4x10 they want the smallest cab that they can fit four tens into.

The more research I do, the more it seems everyone designs cabs different

Plans from BFM and Greenboy are what you should be looking at, because they're designed by engineers who don't have to answer to marketing departments, so they don't have to compromise. They might not have cabs that are perfect for your driver specs, but they're not going to be that far off either.

 

[CoffeeLove]

Not necessarily. Do a little modeling with WinISD and you'll find that most cabs are smaller than ideal for the driver. It's a classic example of marketing trumping engineering.
Plans from BFM and Greenboy are what you should be looking at. They might not have cabs that are perfect for your driver specs, but they're not going to be that far off either.

Ya, this is my line of thinking. It will be slim chance that I can actually tune the cab to perfection, so vetting close will need to be OK. And, I could always decrease overall volume inside a cab (add filler inside, yes, a little weight as well), but cannot increase volume if the box is too small.

 

[seamonkey]

Hoffman's Iron law
...three parameters that cannot all be had at the same time": good, deep low-frequency sound, a small cabinet size, and high sensitivity.

Software for modeling cabinets is a good first step. If the software is left to it's own it will specify a cabinet much larger than most cabinet makers would make. If you prototype that cab, versus some optimal size cabinet you'd know how much you're giving up for size.

It seems people want "Wall to Wall" speaker cabinet look. Looks take precedence over actual cabinet performance. Looks sell. And then there are makers who overy-cram in more drivers, some into what looks to be a shelf port, because "more is better". It works though because most people can't tell what real bass sounds like. They like a peaky boost above the actual bass frequencies. Since they never hear a cab with closer to ideal size and port, they are none the wiser.

 

[CoffeeLove]

Eminence actually has cab specs for their various drivers, and some "supposedly" designed to match Eden specs. Seems like a great place to start, will also look at Fearful designs. Thanks to the TB member that sent it to me. Here is the link, it is the 3rd cab design in the cabinet design PDF file. Seems a bit shallow, but also quite tall for a single 10" driver. Looks good to me.

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[agedhorse]

Not necessarily. Do a little modeling with WinISD and you'll find that most cabs are smaller than ideal for the driver. It's a classic example of marketing trumping engineering, and what people want to buy is small cabs. Even if it's a 4x10 they want the smallest cab that they can fit four tens into.
Plans from BFM and Greenboy are what you should be looking at, because they're designed by engineers who don't have to answer to marketing departments, so they don't have to compromise. They might not have cabs that are perfect for your driver specs, but they're not going to be that far off either.

Actually, this is not all that true.

Many players simply can not, no matter how much you or anybody else suggests, recommends, mandates or belittles, pack around a "large enough" or "heavy enough" cabinet that might otherwise offer "better" performance.

It's not at all a matter of marketing trumping engineering, it's a matter of engineering providing the best possible solution to fit the player's wants/needs/desires. EVERYTHING is a compromise, and for many players, very large, or heavy cabinets are a MAJOR tradeoff, far more undesirable than giving up a bit of LF extension. I am an engineer, I don't answer to marketing departments, but I do pay close attention to what players here (and elsewhere) are asking for and do my best to deliver the best possible combinations of tradeoffs that meet the most player's needs as possible. Just because YOUR priorities are different than other players doesn't make it right to insult players who might have different (and just as valid) priorities as yours.

And to say that BFM and Greenboy (and EVERY OTHER DESIGNER) doesn't have to compromise is simplistic tunnel vision, as we all operate within the same laws of physics and acoustics. They may have made a DIFFERENT choice of compromises than myself and others, but that doesn't make them any better than myself, and likewise it doesn't make my choices any better than theirs, just different.

 

[Blues Bass 2]

That design looks pretty good .
You might have trouble finding that size port tube , 2 1/4" inside diameter isn't real common . The 210 uses 3" vents that are real easy to get . You could build a cab half size from the 210 design at 1 1/2 cubic feet interior demension and use two 3" ports about 2 1/2" long . The cab sizes that Eminence gives you are great but as long as you can figure out the cubic feet for the inside of the cab and juggle the outside size with the baffle inset about 1 1/2" you can make it deeper or whatever works for you . I've built several cabinets using Eminence pdfs like you are looking at and they all came out very nice . There is more fudge room in cab design that some will admit but as long as the speaker you are using has similar specs as the Eminence speaker and you keep the cubic inches and port size and length close it will probably work pretty well . Either of those designs would probably be fine .

 

[BadExample]

It's been almost 30 years since I designed a ported cab (did the math by hand, and I had a very good pro-audio engineer to run the results by), but IIRC changing the cab size changes the tuning. The upside is with round ports, they are easy to change, so you can tune by ear. If it sounds good, it is good.

Do a little modeling with WinISD and you'll find that most cabs are smaller than ideal for the driver.

In some applications, the trade off of a smaller cab is better for the sound, and/or power handling (mechanical).

Many players simply can not, no matter how much you or anybody else suggests, recommends, mandates or belittles, pack around a "large enough" or "heavy enough" cabinet that might otherwise offer "better" performance.

I dunno, I had no problem getting that 89# Bag End down two flights of old university stairs and loaded into the back seat of my Jeep (I'll never do that again). Then from my Jeep to my shed (never do that again) and finally from the shed to my living room (never do that again). I will tip it on it's side and install poly wheel heavy castors on it. And I will roll it out to a shipping container and make my wife push it up the ramp (she won't do that again)

But then, I did trick her into marrying me, and into at least semi-accepting the rat fur Bag End in the living room.

 

[CoffeeLove]

The upside is with round ports, they are easy to change, so you can tune by ear. If it sounds good, it is good.

It would be great if I could use these port tubes and go with round ports, would also make it easier than trying to build Eden style ports. The port tubes are 2"x4" see pics.

 

[agedhorse]

Baffles or baffle board is what the drivers mount on, the ports are called port tubes or duct tubes. I think there's some confusion going on with how things are being described.

 

[CoffeeLove]

Oops, sorry, just fixed that last post. See, I am clueless, but glad you are here to help. Would they work, be large enough? Thanks

 

[bobcruz]

Oops, sorry, just fixed that last post. See, I am clueless, but glad you are here to help. Would they work, be large enough? Thanks

There's gonna be math involved.... When you choose a cabinet design from the Eminence PDF plans, it will have a port tuning frequency. You can generally reverse engineer that frequency from different sized port tubes--the length and diameter will determine whether they match the frequency based on the net internal volume of your planned cab. As long as the ports have sufficient area to avoid excess air velocity (which causes a noise usually called "chuffing"), you'll have the same results as predicted by the Eminence plan. So we'll need the net internal volume and port frequency from the Eminence plans to figure out what diameter and length of ports will work.

 

[BadExample]

There's gonna be math involved.... When you choose a cabinet design from the Eminence PDF plans, it will have a port tuning frequency. You can generally reverse engineer that frequency from different sized port tubes--the length and diameter will determine whether they match the frequency based on the net internal volume of your planned cab. As long as the ports have sufficient area to avoid excess air velocity (which causes a noise usually called "chuffing"), you'll have the same results as predicted by the Eminence plan. So we'll need the net internal volume and port frequency from the Eminence plans to figure out what diameter and length of ports will work.

Bob, not questioning your wisdom, but do you think modeling off the TSP's from a driver that it said to work (and probably does) in a given cab will yield acceptable results for a new cab design? I'm a bit of a loss for words, but thinking something like rounding error, or maybe re-compressing a jpeg or mp3 20 times. Maybe it depends more on how well the alternate replacement works?

BTW: We call it huffing here. A reason why so many Hoosiers are so dumb.

 

[CoffeeLove]

There's gonna be math involved.... When you choose a cabinet design from the Eminence PDF plans, it will have a port tuning frequency.

Here is one that is supposed to be modeled after the same speaker (Eden EC1060XL), there is a cabinet design PDF, and it is the 3rd cab down in the PDF. It actually calls for 2" ports I think. I do not like how shallow the cab is, it does not need to be a cube, but it sure seems shallow and tall. Looks like total volume should be .68 cubic feet.

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[Blues Bass 2]

Here is a half size cab of the 210 in the top pdf .
Height 17"
Width 13"
Depth 16.5" Front of baffle 1 1/2' recessed
This will give you 1.581 cubic ft. or half what the 210 interior volume would be before bracing and speaker volume . Add two 3" ports 2 1/2" long and you are good . The dimensions are with 1/2' plywood , if you use 5/8" like you said it will still be close enough . The F3@ 62Hz . per Eminence specs , not bad . These 3" flared ports have a useable length of 2 1/2" , just right for this cab .
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You can also get PVC plumbing pipe , the thinwall type and cut it to length . You can get short lenths at Home Depot or Menards . The flared ports are large and can be mounted on the back of the cab . Not much difference between front or back porting , it can be done either way .

The small vented 110 cab you were looking at is tuned higher and handles a little more power but it would be very shallow and I think the bigger cab would be easier to use with a head on it . Hard to find 2 1/4" ports too .

 

[fdeck]

You can always build a speaker with flat response down to your lowest fundamental, and then decide that you hate the sound.

In addition to what @agedhorse says about tradeoffs, the designer also has to consider what will actually sound good and behave well according to the bassist using it under their anticipated range of operating conditions. An "optimal" design is not necessarily the best choice. My guess is that a 1x10 cab will see most of its use indoors, where room acoustics have to be considered. I've never been in a small performance space that was friendly to the 40 - 80 Hz range.

I'm just one bassist, but my first DIY design was an "optimal" cabinet. It was horrid, and it ran me out of patience and money, so in desperation I sealed the port, and then it sounded just fine. Limiting the low end response (coincidentally making it more like typical commercial bass speakers of the day) made it much better behaved, especially in poor acoustic environments such as the high school band room and auditorium.

Since then I've formed the view that one of the hardest parts of DIY design is deciding how you want it to sound in the first place, and how that translates into quantitative design targets, such as the response curve. I've had some success by measuring the response of speakers, so I could form a relationship between the measured curves and my listening / playing experience.

 

[CoffeeLove]

Height 17"
Width 13"
Depth 16.5" Front of baffle 1 1/2' recessed
This will give you 1.581 cubic ft.

Cool. Isn't that almost 3X the suggested volume compared to the Eminence 110 cab design recommended for that speaker? They suggest .68 cubic feet. I "do" like the idea of a cab that is "closer" to a cube shape, the Eminence design seems excessively tall and shallow. Please correct me if I am wrong, which is likely. The speaker will only be used in smaller rooms and for low volume rehearsals, unless it is amazing. Thanks

 

[Blues Bass 2]

This is also an Eminence design from the same engineer only in a larger cab tuned lower . You lose a little power handling but get a lower tuning . fdeck know his stuff so maybe the small cab would be the way to go for what you want to use it for but I think the larger one would sound very good too . With a 110 cab you are only going to get so much , no magic .

 

[bobcruz]

Bob, not questioning your wisdom, but do you think modeling off the TSP's from a driver that it said to work (and probably does) in a given cab will yield acceptable results for a new cab design? I'm a bit of a loss for words, but thinking something like rounding error, or maybe re-compressing a jpeg or mp3 20 times. Maybe it depends more on how well the alternate replacement works?

BTW: We call it huffing here. A reason why so many Hoosiers are so dumb.

No claims to wisdom here--I'm just trying to suggest something that may work. Without expensive testing equipment to derive the TS parameters, there's no way to guess how the original Eden speakers will react in any design other than an exact copy of an Eden cab. So I pointed CoffeeLove to the Eminence plans as at least a rough starting point. (By the way, Eminence makes Eden's speakers and has for years; I'm a bit surprised their licensing and nondisclosure agreements allow them to market a speaker that they can say mimics the "Eden sound." But their frequency response chart for the "Eden sound" speaker sure does look like how the Eden speakers sounded to my ears.) If these were my speakers, I'd sell them and get something that has published TS parameters, but experimenting is fun and since the OP got the speakers free, this can be a fun learning project. The basic size of the box for the Eminence driver is probably "good enough for government work" and the ports can be tuned by ear after starting with the Eminence targets. It's the best I could come up with.

 

[CoffeeLove]

The basic size of the box for the Eminence driver is probably "good enough for government work" and the ports can be tuned by ear after starting with the Eminence targets.

So, how can I change the dimensions and still get close to the same volume? It would be great to use the 2x4" port tubes I already have, see pics. I could play with the numbers and probably figure it out. It would be nice if the cab was a bit shorter and deeper than the Eminence specs, maybe only 16" tall, just so I could safely put an amp on top. O ya, you people are awesome!