Bass Cabs: How Shallow Is Too Shallow?

[FerruleCat]

(Sorry for the long setup here...)

There's a Bassman 215 cabinet at my local pawn shop that I think I could score pretty cheaply on an "OBO" sale. It's a little rough around the edges, but in that cool garage-band way. (I know visuals don't contribute to tone, but there's something about a beat-up old Fender box.)

I was researching this cabinet here on TB, and I ran across some decidedly negative opinions. The best I could tell, there's some thought that the shallowness of this cab contributes to a poor, muddy tone.

My Peavey 1-15 Black Widow enclosure also is quite shallow, and while I don't have any issue with the tone, it has more top end than I would have expected. (Not muddy, though.)

I've had my eye on the Dayton PA380, which is an affordable 15" driver that does very well in smaller volumes. In fact, I've modeled a 215 at 5 cubic feet that would be quite decent. It gets even better at 6 cubic feet, however, with a +2dB plumped low-end response and much lower port velocity up to 600 watts.

I think the Bassman 215 is in this neighborhood and might be made to work well with a pair of Daytons, as long as it doesn't have some fatal dimensional flaw. (But unless it's easy pickings, I don't want to go down the road of trying to force the cab to work. All else equal, if I can save some labor not having to build the enclosure, and get it cheap, and get the cool looks to boot, it's a winning proposition.)

So after all that setup, here's my question: Aside from hitting the right overall cabinet volume, is there also a critical threshold for any particular dimension? I know we have to leave clearance for port tubes, etc., but just from the standpoint of frequency response, is one 6cf cab better than another? And if so, does that vary with the driver, or are there certain fixed design principles we can bank on?

Many thanks for any thoughts.

 

[BassmanPaul]

That cabinet sounds good with a pair of JBL K140s installed.

 

[DukeLeJeune]

As long as there's room inside for woofers and port(s) and port end clearance(s) and bracing and crossover, and room on top for your amp, the internal geometry of a ported box probably isn't critical. In an undamped cab I think there's an argument for using a golden ratio for the internal dimensions, but the more damping material you use, the less the internal geometry matters, as far as internal reflections go. You don't want to use too much damping material either or the cab will tend to sound lifeless, but fortunately any over-or under-use of damping material is pretty easy to correct.

 

[flameworker]

I had that bassman cab, it didn't do it for me.

 

[JimmyM]

I think the biggest complaint about the old Bassman cabs wasn't the sound but the limited power handling you get due to the size of the box being kind of small for two 15"s.

 

[MIMike]

I found an old Bassman 4x12 because I liked the width and depth dimensions. It matched my Bassman 100 head, but I wanted it to work with my 2, 12" Eminience drivers that I had. I contacted Eminience for the ideal dimensions and cut it down to the ideal size. It came out awesome.

 

[danosix]

(Sorry for the long setup here...)

There's a Bassman 215 cabinet at my local pawn shop that I think I could score pretty cheaply on an "OBO" sale. It's a little rough around the edges, but in that cool garage-band way. (I know visuals don't contribute to tone, but there's something about a beat-up old Fender box.)

I was researching this cabinet here on TB, and I ran across some decidedly negative opinions. The best I could tell, there's some thought that the shallowness of this cab contributes to a poor, muddy tone.

My Peavey 1-15 Black Widow enclosure also is quite shallow, and while I don't have any issue with the tone, it has more top end than I would have expected. (Not muddy, though.)

I've had my eye on the Dayton PA380, which is an affordable 15" driver that does very well in smaller volumes. In fact, I've modeled a 215 at 5 cubic feet that would be quite decent. It gets even better at 6 cubic feet, however, with a +2dB plumped low-end response and much lower port velocity up to 600 watts.

I think the Bassman 215 is in this neighborhood and might be made to work well with a pair of Daytons, as long as it doesn't have some fatal dimensional flaw. (But unless it's easy pickings, I don't want to go down the road of trying to force the cab to work. All else equal, if I can save some labor not having to build the enclosure, and get it cheap, and get the cool looks to boot, it's a winning proposition.)

So after all that setup, here's my question: Aside from hitting the right overall cabinet volume, is there also a critical threshold for any particular dimension? I know we have to leave clearance for port tubes, etc., but just from the standpoint of frequency response, is one 6cf cab better than another? And if so, does that vary with the driver, or are there certain fixed design principles we can bank on?

Many thanks for any thoughts.

I had one of those shallow cabs - the poor, muddy tone is entirely the old crappy speakers. Put a (even close to) decent pair of speakers and it sounds great. I had a pair of Yorkville PA speakers (not exactly world class bass speakers) in mine it sounded GREAT. The depth doesn't matter nearly as much as the overall volume and this cab has LOTS of that.

 

[FerruleCat]

Thanks for the replies, everyone. Given that there's sawdust either way, I'll just build my own enclosure; I can always throw the silver grillcloth and corners on it and get the classic look. I don't remember the specs exactly, which are on my other computer at the moment, but a 6cf cabinet with two slot ports (top and bottom) tuned somewhere in the low 50s looks really good with the Dayton PA380s. I can also tailor the dimensions so it fits nicely through the rear-seat pass-through in my Honda.

 

[AstroSonic]

The Daytons will do fine in that Fender cab. They will also do well in your proposed 6 cf build. I would tend to use tubular ports arrayed symmetrically around the drivers to evenly load the cones. There is some merit in tuning low enough to load the driver(s) down to the lowest note you will be using (like to 41 or 32 Hz). The actual tuning frequency is higher. Tuning in the low 50's would likely load down to at least 41 Hz. If you play a 5 string (low B), you'll want to tune a bit lower, say in the mid 40's.

 

[will33]

Will end up being a nice cab, and yes when doing it from scratch you can taylor it to your situation, like fitting in your car or looking nice with a wide amp on top. Can probably build it a bit lighter and stiffer than the Fender too.

Can always reuse the worn hardware and cloth, and "relic" your new tolex a bit. Kick it around, scuff it up.

 

[will33]

You could also use the Fender box...less work.

I'd just add some braces inside, and perhaps port it using pipes/tubes on the side if there isn't enough depth front to back to put them there.

 

[will33]

Duke has a good point about dimensions and lining. I'd start with lining the back and 2 sides and adjust by ear from there.

Meaning back, bottom (or top), and one side, so there is a lined panel opposing a bare one. Could do that whether using the Fender or a new box really.

 

[FerruleCat]

The Daytons will do fine in that Fender cab. They will also do well in your proposed 6 cf build. I would tend to use tubular ports arrayed symmetrically around the drivers to evenly load the cones. There is some merit in tuning low enough to load the driver(s) down to the lowest note you will be using (like to 41 or 32 Hz). The actual tuning frequency is higher. Tuning in the low 50's would likely load down to at least 41 Hz. If you play a 5 string (low B), you'll want to tune a bit lower, say in the mid 40's.

Thanks very much for that. There is plenty of real estate to add tubular ports to the baffle -- though not great depth to run them. The slot port was going to need some work anyway, since the lip was a bit roughed up. I could just seal that off easily enough.

I play 4-string short-scale and don't look for massive low end, so tuning in the low 50s should be enough. I'm also planning on adding an FDeck HPF down the line for protection in higher-volume scenarios.

Well, this new confirmation adds a wrinkle, because in addition to having the old Bassman cab, the pawn shop has a Fender Mustang bass (looks to be recent reissue in vintage white). I figure if I round up my superfluous gear, I could just about trade across for both and double the "character quotient" of my equipment in one trip.

I'll make a quick recon trip at lunch to confirm my interest.

By the way: You may not have caught my post in the "Mini Rigs of Doom" thread recently, but I recently completed my first design and build: a Kappalite 3012ho in a 3cf box tuned to 55Hz. The low-end gets borderline boomy at high volumes, but otherwise it has tons of punch and clarity. Again, I think this one would benefit from an HPF.

 

[ErikavonT]

That cabinet sounds good with a pair of JBL K140s installed.

I had one with a pair of D140's in it. It didn't scare anybody but sounded nice for the time (1970) with my 67 Bassman head, when I couldn't afford a new SVT.

 

[AstroSonic]

Real nice 3012 build. If you routinely (or often) play at high levels you could avoid 'boom' by tuning somewhat lower - say around 47 Hz. The reason for the booming at high levels is in large part due to the increase in voice coil temperature and resulting higher voice coil resistance (and suspension stiffness, raising Fs). This increases Qts and changes your alignment to a more peaked response. Tuning lower just pre-compensates for this, but results in a slightly over damped alignment at lower spl's. You can boost the bass a little in those cases.

Man, that Mustang would be hard to pass up. Good luck with that.

 

[FerruleCat]

UPDATE: The Mustang, sadly, was out of range for me, as they weren't too interested in trading, and I can't do the cash right now on top of my going projects and the holidays. Too bad; it was a fantastic player. I dig the 7" radius neck, and the setup was right on the money. (There were a few body dings, though.)

But the 215 is now in the back of my Honda -- just barely. It won't take much to seal off the slot port (bottom front), throw in the Daytons, cut in a couple of port tubes, and we're rolling. In the end it will be less work than a scratch build, and kind of a neat refurb of an old box. I'll be sure to document it. (I'll try it stock first, of course.)

Thanks to everyone for the advice.

Thanks also for the 3012 tips, AstroSonic.

 

[will33]

Ypur current Fender cab has a slot port across the bottom?

If it also has what also amounts to an almost 2x4 size brace from between the driver cutouts to the back wall, I had the same cab when I first joined Talkbass. Went with my Bassman 135 head. BFM and others here let me know it sounded like crap due to mismatched drivers of unknown spec and gave me some tips on bracing and lining too. The cab is gone but the knowledge remains.

The lining part is simple enough.

You can tweak the existing port too rather than sealing it up and reporting with tubes if you want. Raising tuning is a little more work as you'd need to cut away some of the "shelf" that makes up the "ceiling" of the port. Lowering is a good bit easier, as it means adding a piece of plywood to extend the shelf deeper into the cab, or, simply blocking off a part of the existing port.

Knowing the cab now, it wouldn't be overly difficult to optomize it for the Daytons, and keep all its look/mojo.

 

[FerruleCat]

I'll pull the drivers tonight, but it feels like the slot port (just one across the full width at the bottom) is only about 1 1/2" deep or so, so there's not much room to cut anything. Per Astro's advice, I'm inclined to seal it off and cut in a couple of port tubes between the drivers for symmetry. The cab is light for its size, so there can't be much bracing at all. I'll add a few well-placed sticks for good measure.

Other points of reference: Two 1/4" speaker jack cups on the back and a "no tail" logo. Serial #F098998. I'll come back and post pics later.

 

[will33]

I don't recall what the port tuning was, but even if it's something lower than 55, I'd play it for a while with the Daytons in it with the port as is, for the reasons Astro mentioned. Mess with more or less linibg to tweak mid response.

IIRC, it's a fairly solid box. Worth putting a bit of work into with drivers like that that don't need a large box to sound like a bass.

Had I known at the time, I might still have the thing, having done something to it similar to what you're proposing here.

That model of Dayton brings the goods, especially from a small box performance vs. cost perspective, but a good solution in any case. Being affordable is a nice perk though.

 

[FerruleCat]

I'm working toward two distinct rigs: 1) Aguilar TH500 with a pair of the suave and scalable B&C 12cl64 cabs designed by LowactnSatsfactn, and 2) Ampeg PF800 with a rough and ready 215. I'm making good progress; I have the Aggie and PF800, and now the 215 box. I also have the wood cut for the B&C 1-12s, with the hardware arriving tomorrow and the drivers backordered and due next week. Depending on how those B&C cabs work out, my Kappalite 3012ho might get sold to finance the Dayton drivers. A guy only needs so many cabs, after all.