DIY Angle Cab - what would you load it with?

Evening all
(Apologies for the rambling post, if you are skip reading move to the bit in bold)
I am just looking for some thoughts on something I am considering building-

I started out with an old Trace Elliot BLX150 combo. It's a strange little unit with a 130W head, a 10" speaker and a little diffusion slot. It's deep but it isn't punchy. I was playing pub gigs and the bass wasn't always amplified, so I took the head out of the combo amp, built a single 15" ported cab (with an Eminence 15" - no tweeter - not certain on the Eminence model as it was 10 years ago - maybe a Kappa Pro 15?), and made a wooden sleeve to make a head out of the amp section of the combo which sat on top.

Now however I'm playing at home and practicing, and maybe with groups like dance bands etc, and whatever we do is properly amplified, DI'd and monitored, so I don't need a 15" cab, and I'd like it to be a bit more compact, and to reduce stage spill I'd quite like an angled cab.

I'm considering using the top of the Trace old combo (I know it's low power and old hat, but I'm kind of attached to it now) and making a small, compact angled combo cab, casing the head as well, with something really small and punchy like 2x8 or 2x10, or maybe 1x12 or 1x10? What would you be building, and how much should I pay attention to cab resonance etc (I did make some 12" & tweeter PA cabs about 10 years ago as well, and drew it all up on WinISD etc - but this was for full range response, what are reasonable responses for a bass cab?) and how much is just judgement and drivers for something which sound is so subjective?

 

To make this a bit clearer I've drawn up a quick sketch of what the angle cab might look like.
I've got three images, one is the head (it's a really shabby cab build..), and two of the kind of size of the combo. I haven't drawn the front of the combo and obviously the size will adjust according to the drivers, and the size of box needed for the drivers..

What would you think of loading it with and sealed / ported box or what kind of design would you be thinking for a small practice/small gigging amp like this?
I'm thinking more of an amp for an orchestra / theatre band pit rather than pub/club gigs

Obvious configurations that would fit would be 1x12, 1x10, 2x10
Further afield - would 2x8 be too small? 1x15 probably too heavy.

 

I don't actually know what the 1x10 in the original combo is - I supposed it must be a decent enough driver but I never considered it. That said I've got the original combo wrapped up and stored so I can turn it back to original if I ever want to sell it, and I'm not too worried about being frugal. I don't want to pay silly money for a driver but can spend sensible money.
By lightweight how would you make it lightweight? Lightweight driver or say 15mm instead of 18mm material?

 

I'd be a bit worried about going down as thin as 9mm but in guess it depends on the overall size of the panels. I guess you need battening with 9mm though that you wouldn't need with 18.

You'd go with single 12 then? If I could reduce that height how would 2x8 compare?

 

I'd say getting a deep sound is more important than pure volume. When I say home playing I might use it outside of home, but most work I am involved in now is cabaret style / lounge style where I'm more likely to need monitoring than proper level.
How would you go about designing the cab, ports (if any) and bracing for the cab? Would you have internal battening on a 9mm ply cab then? This would be a job for the top sleeve where the amp section is- I guess that would still have to be strong enough to be self supporting. Compact is a priority but weight isn't a massive issue

 

Sounds like chimney stacks..

I've drawn up the cab with 2x Eminence Beta 8s (for some reason I like the idea of 2x8 rather than a 12, and I can't fit 2x10 in that cab at the moment


It's approx 31L cab, and tuned with that port to around 58Hz (it's a 23cm port 43cmx3cm, so equivalent area to 12cm diameter port according to my maths - I'm a bit restricted at the moment as I am totally Mac-based at work and home so can only use the online version of WinISD, so it's a bit long winded)

I'm not sure what type of response I should be looking for? It's a terrible way of working, but there is a graphic on the amp so I can change the tonality somewhat.

I also looked at some Neo drivers that are about the same price as the Eminence and have a slightly more interesting curve:



But the drivers are a bit of an unknown - the supplier seems to rate them (they are a pretty trusted supplier in the UK as well) but they look a bit weedy:

http://www.bluearan.co.uk/index.php?id=PAUE8200N

What are anyone's initial thoughts? I could tune the cab a bit - at the moment I worked backwards from the dimensions rather than really tuning the cab for the speakers.

 

Do be honest I can't see cooling be a major issue there but I see what you are saying as with the only port being at the bottom there would be no airflow in at the top - it makes the grill across the two 8inches slightly harder though as it would have to cover the ports as well. I would quarter or half inch round all the edges depending on material thickness but I just haven't bothered to illustrate that on the drawing.

I'll look up the root frequency of that bottom E and make some more informed drawings - thanks for the frequencies you'd be aiming for.

The back story of this is I used to play as a teenager, but haven't picked my bass up for over a decade - I want to make a nice-ish custom amp to start again with. I'm a theatre technician by trade so have the electrical knowledge and can physically build the cabinet (hopefully) to a reasonable standard but the acoustic knowledge is my weakest area - also quite what you're aiming for - I know what the response for all sorts of PA systems should be but a bass amp is so subjective I don't know what kind of response we're actually aiming for.

 

Okay, not a bad idea, you will have to excuse this but I plugged the numbers from that (specs of the driver and box dims & tuning into onlineISD as it's the easiest way for me to compare with the other two graphs)



It's not worlds apart though it is a good improvement - on both we've got -9 at 50Hz, whereas the 12inch B&C is +6db better at 70Hz plus, whereas the dual 8 is losing a lot of power (-6dB) from very high, as you say. I'm going to plug some more numbers and try some improvement.

Link to the 22lb box plotted with B&C in fdecks program - that is nice, still need to use ISDonline to calculate port length for tuning mind
http://personalpages.tds.net/~fdeck...port=64&Aport=34&Bport=3&nPorts=1&PinExc=130&

 

Unfortunately it always draws in green, so I can draw all 3 but still only in green. I do have a virtual installation of XP on my mac at work so I will install WinISD on that when I get back on Tues.

I have got some nicer curves using 2x B&C 8inch drivers but it gets pricey as the drivers are around £120 a piece so the single 12" is more economical. I'm not sure why I'm hung up on dual drivers, it just seems more instinctively to shift more air, and I was considering low passing one of them to give coupling only at the bottom end, but I think I might be being a bit too complicated just for the sake of it.​