A pair of 1x12" cabs

[Beer of the Bass]

I'm just about to start putting together a pair of 1x12" cabs, as I ended up selling my last decent sized cab during a house move and only have a little 1x10" at the moment. With a new musical project on the go this year, it would be nice to have something a touch bigger around.
This won't be a high-end, cost-no-object sort of build; while I don't want to skimp too much I'm trying to keep it reasonable. With that in mind, I've picked up two Eminence Beta 12A-2 drivers which are lightly used but both in good condition. The cost of both including postage was £66, which is about the cost of one new driver. These are not state-of-the-art, high excursion drivers, but I'm confident they will do the job for my needs. My bands are never crazy-loud, I'm currently using a GK MB200 and I intend to mess around with low-wattage valve amps at some point, so it's more important to me that the cabs have decent efficiency and a pleasing voice than massive power handling. There is a certain small company's 1x12" that appears to use the same driver (as the published specs are identical to what would be expected for that driver and box size) and is currently very popular among basschatters, so I'm hoping to come up with something which does a comparable job even though I'm not going to directly rip off their design.
The 1x12" design diary thread has been very useful and I'm going to take quite a few pointers on design and construction from that. My cab is going to be just a touch smaller than the design diary cab, closer to the commercial cab mentioned above. It will be about 46 litres once the ports, driver and bracing are accounted for. I intend to use plastic downpipe for the ports so that I can try a couple of tunings and pick the one I prefer.
I was initially going to use some 18mm exterior ply which a friend was clearing out, but on closer inspection that turned out to be a little too full of voids and has thin outer veneers which would be no good for glued butt joints, so I'll have to find another use for that. I've spoken to a local timber supplier who seem very helpful so far, they've ordered in some birch plywood for me and are happy to cut it to my sizes. Although the design diary thread discussed the merits of 18mm plywood I've decided to go with 12mm to keep the weight down a touch, which will be appropriately braced. I may make the back removable like Phil's prototype, as it would make bracing, lining and installing the ports a lot easier. It would also save me from having as many seams if I end up using tolex.
I'm still considering the cosmetic side of things. The one thing I'm definite on is that I want a sparkly cloth grille - I just think they look good. I'd like the cabs to be something other than black - I'm waiting for Blue Aran to get back to me on the availability of Tuff Cab paint in either Signal Red or Turbo Blue as they're out of stock currently. Alternatively a tolex type material could look good, but looks tricky to apply neatly.
My plywood should arrive by Tuesday, so hopefully I'll have more to post then.

[Phil Starr]

good luck with this. The Eminence Beta 12A-2 is perfectly adequate as a driver with a pleasing peak in the midrange and it will have a bit of bass warmth in a 45l cab so should sound nice. you'll only find it's limitations with high sound levels containing lots of deep bass where the excursion limits become important but that's probably at a level way higher than a drummer if you are using two.

No-one sees the backs on stage so i rarely Tolex them for my own use. I'm a big fan of Tuff Cab having used it on one of my prototypes and it is wearing well on my gigging speaker, It's a whole lot easier than covering with Vinyl and you don't notice any difference on stage TBH.

[paulnb57]

Following this........care to enlighten me on the Tuff Cab paint, I've never heard of it.....

[Beer of the Bass]

[quote name='paulnb57' timestamp='1452268745' post='2948338']
Following this........care to enlighten me on the Tuff Cab paint, I've never heard of it.....
[/quote]

It's a textured paint which can be applied with a roller, it looks a bit different from tolex close up, but still smart looking if done well, plus it can be touched up if it gets scuffed. If you search for "tuff cab" on basschat, there are some build threads which use it. It's a similar finish to a lot of the Barefaced cabs, though I don't know if the most recent ones are still the same.
It comes in black or a few different colours - I liked the idea of the blue used in this build, perhaps with a silver Fender-ish cloth grille. [url="http://basschat.co.uk/topic/243742-fearful-156/page__hl__%22tuff+cab%22__fromsearch__1"]http://basschat.co.uk/topic/243742-fearful-156/page__hl__%22tuff+cab%22__fromsearch__1[/url]

[paulnb57]

Look like a great idea, thanks Beer!

[JTUK]

I think you could do a lot worse..... a LOT worse, IMO.

I would rip the box myself but I doubt you'll get it as light ...but anyway
the design rip is a tone monster, IMO, and I think I've heard most of its competition.

[Beer of the Bass]

[quote name='JTUK' timestamp='1452281250' post='2948543']
I think you could do a lot worse..... a LOT worse, IMO.

I would rip the box myself but I doubt you'll get it as light ...but anyway
the design rip is a tone monster, IMO, and I think I've heard most of its competition.
[/quote]

I would feel a little cheeky trying to build a straight rip-off of a currently available product from a small company, and even more so documenting it publicly, but on the other hand looking at what they do and taking some hints from it seems OK to me. It's quite possible that some of my guesses would be wrong anyway! So, more work-alike than clone is what I'm going for.
Mine will almost certainly be a little heavier as I'm using birch and not poplar, but it's a small 1x12" so they won't be outrageously heavy.

[paulnb57]

I'm going to do something similar soon, so I'd appreciate it if you could share dimensions and method please.......great project!

[JTUK]

[quote name='Beer of the Bass' timestamp='1452287183' post='2948631']
I would feel a little cheeky trying to build a straight rip-off of a currently available product from a small company, and even more so documenting it publicly, but on the other hand looking at what they do and taking some hints from it seems OK to me. It's quite possible that some of my guesses would be wrong anyway! So, more work-alike than clone is what I'm going for.
Mine will almost certainly be a little heavier as I'm using birch and not poplar, but it's a small 1x12" so they won't be outrageously heavy.
[/quote]

Yes, see the point and you're building your own anyway, so you're going to step on someones toes..

I assume you can keep internal Dims...which the chassis dictates to a degree anyway and just increase the lenght, height etc
and compensate elsewhere.

I'm not sure what the 'trick' is... maybe it is a very happy accident to arrive at the sound of these boxes in quite the way they do,
but to my mind, they have a very agreeable mid without it is being harsh in anyway.

On a popular theme and generally, NEO's do this but it is a harsher mid to my ears and the bottom is 'fake'
so all round the sound is plastic.
If you tune out the mid, you are left with too much bass which takes away the character, IMO.

I'm sure we've had these debates elsewhere but this is why I always think of NEO as a bit
'meh'

Now, of course, you don't have to worry about NEO being the solution to weight issues
as the cab we are talking about is lighter anyway than any NEO cab I know of the same chassis
size.
I haven't found the downside there yet.

[Beer of the Bass]

I'm still waiting on my plywood, but I've been looking some more into covering materials in the meantime. I've worked out that I would need at least 2 metres of Tolex and it isn't cheap, plus thinking back to the number of bad DIY tolexing jobs I've seen makes me think it might take some practice to do well. I'm leaning towards the Turbo Blue Tuff Cab paint, plus a cloth grille using the Fender style silver, perhaps with some piping around the grille.
I've also got my cutting list together for the panels. I'm going with external dimensions of 52 x 39.4 x 33cm, which is just a touch larger in one dimension than the commercial cab I was comparing it to, but I'm constructing it with corner cleats which take up a little extra volume compared to other joints. I wanted to keep it that width so that if I change amps in future, a typical 19" wide amp won't look daft perched on top. With the baffle recessed by 25mm for the grille the gross internal volume works out at 51.57 litres. The pair of cabs fit onto one full sheet of ply, leaving some offcuts for bracing and grill frames.

[JTUK]

For reference, I use mine horizontal so a 19" would fit anyway.

Single chassis aren't a dispersion issue either (never is, IME) so coupled with the fact that
I hear mine perfectly stacked in pairs ...which we know is only 65cms or so,
combined...so if these come out close to the 'competition' you'll not have trouble hearing them
anyway.

[Beer of the Bass]

My plywood is in stock at the timber merchant and I'm going to pop round with my cutting list later on.
I've been looking at the different options for porting, whether to tune relatively high at 50Hz, low at 40Hz or somewhere in between. Tuning at 50Hz produces a bump of just over 2dB at around 120Hz and improved power handling from 50-100Hz where a lot of the energy in a bass signal lives. The downside is that the power handling at 30Hz is very low, which is likely to be fine in practice but could be risky if I ever turn up the bass knob and really hammer the low B string. Tuning at 40Hz reduces the bump to a little over 1dB and improves the power handling at 30Hz, but lowers the power handling from 50-100Hz.
I've taken some screenshots from WinISD to illustrate this. 50Hz is in blue and 40Hz is in green.

[b]Frequency Response[/b]


[b]Maximum Power[/b]
[b][/b]

[b]Cone Excursion[/b]
This shows the cone excursion at 120 watts. The red line shows Xmax, and Xlim is at 11mm. This shows that if my GK MB200 somehow ended up producing its full output at 30Hz, the driver could be damaged with the 50Hz tuning. However, this seems unlikely given that it will be receiving a bass signal rather than a sinewave generator. With the 40Hz tuning, it exceeds Xmax but stays within Xlim, so would distort but be less likely to be damaged.



At present I'm most inclined towards the 50Hz tuning, unless anyone wants to convince me otherwise. Although I play 5-string, I rarely play the lowest notes and I'm not playing styles involving heavy bass boost. If I ever get into playing in louder situations with a more powerful amp, I would look at introducing a high pass filter into the setup. Another option would be to use multiple ports and plug one to alter the tuning - with some fiddling in WinISD it looks like I could use three 64mm ports 21cm long for a 50Hz tuning, and with one port plugged the tuning would drop to approximately 41Hz. It might be worth doing this and spending an hour or so playing through it at reasonable volume before deciding which tuning to keep.

Edited January 13, 2016 by Beer of the Bass

[6v6]

FWIW I went through the same process with my 1x12 DIY build (using a Beyma SM212 driver), and settled on the 50Hz tuning.

I started out w/50Hz, then tried 40Hz tuning (shelf port where I can add/remove an extension piece) - after gigging both I decided the reduction in power handling at 40Hz using a single cab wasn't ideal, and it pulled some of the guts out of the sound, e.g turns out I prefer the response not completely flat.

Worth trying both tho, as it's quite a subtle difference.

[Beer of the Bass]

I've picked up my plywood. It came from MKM Building Supplies, who are at my end of Edinburgh. They ordered in a sheet of 12mm birch for me which looks to be really good quality with even plies and no visible voids. They cut it to size on their big table saw too, which was well worth the extra couple of pounds as it's accurately cut with square edges and saves me from faffing about with an 8x4" sheet. It was £45 for the sheet, not the cheapest I've seen but not outrageous either.
I have four pieces each of 520 x 330mm, 370 x 330mm and 496 x 370mm, plus enough offcuts to use for bracing etc. Next I need to pick up some softwood for the corner cleats and a length of tubing for the ports.

[rk7]

Subscribed!

thank you please

RK7

[stevie]

As far as I can tell, 5-string players are happy enough with bass cabs designed for use with standard 4-string basses. However, the beauty of doing it yourself is that you can tune the cab to your own specific needs. I don't think you will actually hear any difference between a 40Hz and a 50Hz tuning, as the rolloff is an octave above the tuning frequency (unlike 6v6's Beyma cab) and the small change in frequency response is therefore unlikely to be audible.

There will be a difference in power handling though. The only problem, which you obviously are aware of, is that you will have to sacrifice some power handling at around 80Hz to get extra power handling at 30Hz. Personally, I'd stick with 50Hz, especially as you don't use the lowest notes of your 5-string much, but it could be worth comparing the power handling of the cab with a 40Hz tuning. Also worth bearing in mind is that a higher tuning frequency gets you a bigger port area, which is quite important with a cab this size.

[Beer of the Bass]

Yes, there's only about 1dB difference in the size of the midbass bump between the two tunings, which is going to be very subtle if I can hear it at all. There isn't much difference in the steepness of the roll-off below that either. I can fit three 64mm ID ports in a box this size at 50Hz (four ports work out longer than the box depth) and it looks like I'd be likely to exceed the driver Xmax before the port air velocity gets high enough to be problematic.
My old cab which I wound up selling (which these are replacing) had similarly low mechanical power handling at 30Hz and was even limited at 40Hz, but in practice this didn't cause me problems with the amps I use and volumes I play at.

Edited January 15, 2016 by Beer of the Bass

[Beer of the Bass]

Bits of plywood!


Left to right are my top/bottom, sides and baffle/back pieces. I ought to take some more photos than this, but this morning I did some marking out and cut the corner battens to size. Hopefully tomorrow or Tuesday I'll have them looking like a box, then it will be on to bracing and cutting out the baffles. I'm using Edinburgh Hacklab, a shared workshop space, as I don't have the sort of work space to do this stuff at home.

[Beer of the Bass]

A little more progress; they're starting to look box shaped. I'm using ordinary PVA woodworking glue, with screws through the corner batten because I don't have many clamps. I used 20mm square softwood in the corners, largely because it was in the bargain bucket at Wickes and the other sizes were full price. The back is going to be glued in, but I'll keep the baffle removable, with a 20mm wide flange along the inside for it to screw to which will be sealed with gasket tape. I need to take about half a mm off one end of the back panels before I glue them in, as it turns out they're very slightly oversized. I might fit the vane braces to the back panels before gluing them in, as it would save some faffing around in a confined space. The back panels are a very snug fit, so I reckon I can get a decent glue joint without using battens along the back edges.

Henry the hoover gazes on in admiration:

[stevie]

Looking great so far!

[Beer of the Bass]

A little more progress - vane braces glued to back panels:



Back panel glued into cabs. Nice healthy glue squeeze-out here!



I've used some woodscrews through the outside to hold things together (in lieu of clamps) while gluing - I'll remove these and fill the holes when the glue is dry.

[Beer of the Bass]

I did a little more this afternoon. First I had a look at the joints that I'd glued up last time and went round with a block plane levelling up anything that was not quite flush. I'm quite happy with how neatly the joints have come out and I don't think I'll have any issues with air leaks from them. The screw holes will be filled and levelled later.



Then I cut the offcuts into 40mm wide strips for the bracing. I am cadging Phil Starr's bracing approach from the 1x12" design diary, as I thought this would save me the trial and error of trying to work out my own bracing scheme. Cheers for that, Phil!

[PlungerModerno]

Good work - I like the idea of screws as cheap but serviceable clamping. As the design uses some stiff and heavy duty ply as it's main panel material - it should work great. It won't be the absolute lightest (I think there are some composites used in planes & F1 that could be significantly lighter with the same stiffness) - but for the job in hand, a 1x12 shouldn't be backbreaking. Just lift with a back as straight as possible - or better yet bring a hand cart!

[JTUK]

I just have the feeling that these cabs will sound good...

[Beer of the Bass]

I did a bit more; the bracing is now glued in. In hindsight this would have been much easier if I had done it before gluing the backs on - I'll know this next time! It took quite a bit of sketching on paper to make sure that the bracing, ports, speaker and handle bolts don't occupy the same spots, but I managed to fit it all in there. The bracing has easily been the most faff-y part of the build so far, so I could see the appeal of using a heavier plywood and less bracing if you want an easier build.


Next up will be fitting the flanges to attach the baffle, and preparing the baffles.
I've also picked up my paint, grille cloth and hardware. They will be Tuff Cab Turbo Blue, with this grille cloth; [url="http://www.tube-town.net/ttstore/Tolex-Grillcloth/Grillcloth/Grillcloth-Tube-Town-Silver-Line::6592.html?language=en&MODsid=rlemtoaog15ncl5uki2n8l9hr7"]http://www.tube-town...ncl5uki2n8l9hr7[/url]
I went with this supplier because I needed some amp parts from them at the same time, so it was convenient to only have to pay one lot of shipping. In the flesh the silver stripes are quite sparkly, but it the rest it is black rather than the grey of Fender grille cloth. I think it'll look quite classy with the blue finish and chrome corners.

Edited January 27, 2016 by Beer of the Bass