Phil Starr

So this is the excursion of the speakers at 300W. The horizontal red line is where the excursion starts to distort. If the excursion reaches 0.09 (9mm) the speakers will be damaged and eventually stop working. You can see the lowest excursion is at high frequencies and at the tuning frequencies of the ports 30,50 and 60hz in this case. The only tuning that runs into distortion at high power is the green/lower tuning. They all go into damage levels below 40Hz/bottom E at full power but it's a lot lower in the lowest tuning. Even if you are reading this and have no intention of building a cab it's worth knowing that this shaped curve is the same for every ported cab and your bass cab almost certainly can be forced into damage mode at low frequencies!!!! However don't panic. There is almost no fundamental coming out of your bass pickups. they are placed well away from the middle of the string and that reduces deep bass. Most of us don't have amps that go down to 40hz without rolling off either. There isn't any reall evidence of a lot of broken Ampeg VB212's or any other cab of this type. For me this graph shows that any of the tunings will work without issues but it's not a bad reminder of using an HPF if you have one.

At this point we have a design brief ready and the parameters are loaded into the computer so now it is simply about tweaking the design. I'm looking for a roughly 90l cab for two Eminence Basslite 2012's, the shape will be determined by the needs of the user so now all I have to do is tweak the design and see what I can squeeze out of the cab. I'm starting out by looking at the tuning. I've bracketed my 50Hz tuning in blue with 60hz tuning in red and 30hz tuning in green. I'm quite liking 50Hz tuning. Theres a 2db hump of extra bass at 100Hz which will warm things up a bit and give that old school thump. 60 hz increases the hump to 3db which I would find intrusive and would be hard to tune out. 30Hz tuning gives a flatter response and a slower roll off (but from a higher frequency) but is more like the measured bass response of the 2x12 Ampeg SVT cab. This is down to Martin's taste I think, so the question is: In your face bass warmth, Ampeg like gradual roll off from fairly high up or a compromise somewhere in the middle? Before you choose there's another consideration, how does this load the speaker cones and will this affect power handling?

OK one last thing to bring everyone up to date, @police squad asked about a sealed cab. Once you have the speaker's mechanical and electrical properties loaded into WinISD it's a matter of seconds to model a range of cabs so I sent him this: The purple line is the sealed cab, the red line is a 90l cab and the blue and green lines are for 200 and 300l cabs. I actually quite like the sealed cab, it has the flattest response and -3db is around 75Hz so all the second harmonics of a 4 string bass will be accurately reproduced and Eminence also have this design which they describe as "ultra clean" which is probably a very fair description of how this would sound. However you can see how much bass is lost compared with the three ported cabs and the bass hump at 100Hz will also warm up the sound and add a bit of thump which is what Martin wanted. I'd had the other two cabs there to play with different cab volumes to see if I could squeeze a bit more bass out of the cab. The 300l cab in green has a whole lot more bass and a flat response but 300l is an absurd size for a cab if you have to transport it. I'm only showing this to demonstrate that all cabs are compromises of practicality cost and sound and I suppose to say that I did look to see if there were any advantages to a slightly bigger cab.

Thanks David. Martin @Mottlefeeder managed to find them too. The "small vented cab" is 45l and to 55Hz for a single driver. My first guess was to use a 90l cab tuned to 50 hz which is the approximate volume of the Ampeg cab we are copying so in this case it's reassuring to know I've come up pretty much with the same design as Eminence. It may even be that Ampeg knew of this design when it developed the VB212 but to be fair there are only so many sensible solutions for any given driver.

This is interesting, it's the measured response curves of the SVT212. Obviously ignore the top end because we won't be using a tweeter but the bottom end shows a similar roll off to your speakers in a 90l cab, It rolls off really quite high from 150Hz but also quite gradually so it is around -10db @ 50Hz. There's a big drop in everything at around 1300 Hz, which I'm guessing is the crossover. The red line is the response straight ahead and the colours are off axis. You cvan see how much the mids are lost off axis and this is increased because of the sideways displacement of the speakers. You get quite a lot of off axis fall off anyway due to the size of the 12" drivers but the cab is over 600mm wide so it's like having a 24" driver rather than a 12. Above 2,000Hz you are looking at the response of the horn which isn't relevant if you are building a tweeterless cab. I'm not a purist in these things, if you've tried the SVT and love the sound then you can build something like a horn free SVT. Without a horn the off axis problems will be worse but if you tried it with the horn turned off and still liked it then that's clearly somethign that doesn't worry you. If you want a cab the same width as your amp but with the speakers in line then you can do that too and it will be slightly easier to hear yourself on stage.

You could go for this shape

OK a bit of a recap. on our discusion so far. This is the cab Martin wants to copy but he won't use the horn driver so we are leaving that out. I suggested that he would be better with a taller cab and putting the two 12" drivers in line to improve dispersion and the audibility on stage. Anyway this is the cab we are 'copying'

That's my fault, I'm a details person and I just assume everyone is as fascinated as I am about loudspeakers. I'm a riot at parties 😂

Hi, I've put in the speaker parameters and run a quick check. Get ready for a blizzard of graphs. The first thing is that these speakers are underdamped, basically the magnets/motor systems are small giving a very 'American' approach to bass. The sort of warm/bloated sounded you might expect from Ampeg To get lotsof deep bass extension and a flat response they would need a huge cabinet. This is a pair of them in a 100,200 and 300litre enclosure The one in bold is the 100l cab which is roughly the size you are planning. The 300l cab gives you output down to roughly 33Hz -10db and the flattest response but you wouldn't want to fit a 300l cab into a car never mind carry it. However you probably wouldn't want that much bass anyway in a gig situation. I just want to show you the choices you are making

Hi Martin, I've had a quick look on the Eminence website and these speakers look like they would work in a 50l cab or 100l for the pair. They are very high efficiency and have Eminence's typical midrange peak so good for creating an old school sound. Eminence used to offer cab designs for all their speakers but I can't find them as they have re-built their website. The designs may still be there of course. In performance the basslites will be very similar to the ceramic magnet Beta12-2A as used in dozens of commercial cabs so you'll end up with something sounding like TC/Markbass etc etc. Not exactly, but in that sort of ball park If you are a valve man you'll probably be looking for that sort of sound rather than FRFR anyway so they could be a great match.

Hi all, I had a recent request from @police squad for help with a 2x12 design. I've started to do this via PM but thought other people have asked for similar designs and people might like to follow the design process. Basically it involves me asking a series of stupid questions to home in on exactly what he is going to try to achieve. Then I run computer models and ask more questions to home in on what I hope will be his best speaker. Anyway this was his initial question

Not by one of the mods I hope? I'm kind of surprised that when people ask for help and others offer to go over to help out in person that there isn't a response, but I've also posted questions myself and fogotten the thread for a few days because I've solved the issue. I always feel as if I've been unintentionally bad mannered but it's never intentional. I do like a happy ending though, so it would be nice if @proy900 did come back and tell us it's all up and running

It's the amp @stevie uses

The system you’ve got is easily enough for your needs. As Dad has said you will have feedback problems way before damaging the speakers. The amp is excellent, the mixer is fine and the speakers will probably be reliable though the vocal sound will need some tweaking. They’ll do a job for you but might be the first things to replace if you are unhappy with the sound. You might need to address the room acoustics too but you’ve nothing to lose by just setting up and giving the system a try. Again once you let us know where you are based I’m sure someone will help you do the basic set up

Maybe we need to run a wiki of some sort on routers, they are probably the most difficult power tool to use. It's much safer all round to only use them with a jig or mounted on a table. I have a 1/2" router that I use for cutting kitchen work tops and any big jobs I do like shaping architraving or skirting boards. I pretty much won't/can't use it freehand for anything I have router tables so the machine is static and I move the workpiece, I also have an ELU 1/4" router which has a bit of a soft start but even so you can't start it enywhere near the workpiece as it still needs a lot of strength and skill to manuvre. It's roughly 1HP so it's literally got a kick like a horse and routers operate at really high speeds so it's like guiding a gyroscope, it wants to go it's own way. I round all my edges with it in mounted in the router table and move the cabs. I'm wondering about getting one of the little trimmers for the odd small job.

Don't tell anyone but my BC110T is my favourite speaker, it never sounds wrong and I've had a couple of sound engineers, when mixing the band at festivals, describe it as the best sounding bass cab they've ever heard. It's a little gem that just gets the balance right.

Really enjoying this and it's stimulated me to spend a few hours finding out how to use mine properly. I've an ancient DeWalt getting little use. You Tube as ever came up trumps and many thanks to @alittlebitrobot for this really informative and such a clever way to demonstrate what I for one have been doing wrong, I'm afraid I've been using it like my table saw and not getting the best out of it.

First of all well done, they look great and I'm waiting for the results you find when you finally get them to a gig. Concentrating on the financial side alone that adds up to £805 including the grilles and that is for two speakers. For that you have two speakers which are 'almost Silverstones' and which have the same care over the crossover design that @stevie always uses. I've had the pleasure of following the development of this with numerous listening and measuring sessions in Stevie's workshop and then listening to the subsequent deveopment of the Silverstone Mk1. I know there were changes to the crossovers which improved the sound in the commercial Silverstones but the most significant to my ears was the use of the Celestion horn which you do have. I too test stuff out at home listening to classical recordings and I'm sure you'd hear a difference but in reality that's a tribute to the sensitivity of the human ear. Your speaker would sound the same as a Silverstone with just bass going through it in a band situation. I know in listening tests the BC112 mk3 would leave the Barefaced offerings way behind in everything other than weight. In terms of cost I think the Silverstones were originally £599 so by building you saved nearly £400. I reckon that's a pretty good return for your labours. However it's a remarkable observation on just what a bargain the LFSys cabs are. You'd expect the materials cost of a commercial speaker to be around 30-35% of the cost at most. Add on labour, production and distribution costs and that initial Silverstone should have been somwhere in the £1,000-1200 price bracket. It's only by selling direct and limiting production that LFSys can keep the prices so far below their competitors. The reality is that your speakers are worth £1,000 in terms of the quality of sound they will deliver and what it would cost to buy the equivalent commercially buying from anyone other than LFSys.

I was really impressed with this the first time I saw it and more so now I've had a follow up listen. I think this puts to bed the arguments about putting bass through PA with no back line or the use of (great) quality 12" tops without having to use subs. It clearly can be done and outdoors too. It also shows you don't have to sacrifice bass tone because that was spot on too. That's not saying that subs are inappropriate in other situations with different music, bigger arenas or for whatever reason but that this is a PA with wide applicability which would do most of the gigs the majority of us do. I wouldn't claim to sound this good but I gigged for four years with QSC K12-2's and never a problem or hiccup with bass and Kick going through the PA. We used subs twice I think in four years and only for outdoor gigs. And Al I love the band

Look up Tuff Cab paint from Blue Aran applied by roller it gives a fantastic professional finish and is genuinely tough as you'll find out if you ever have to sand it off. It'll also be ideal for renvating your 2x10 and a can will probably do all three cabs.

That sounds like a plan Good Luck

Thanks John I've no knowledge of which drivers they've used over the years though I do know one enquiry a few years back for TS parameters yielded the answer that they didn't know what they were which was a little bit of a surprise

Hi David welcome to the party. I see you live in Exeter, not too far from me and I've played in Exeter a lot over the years, including many of the open mic venues. You'll find the 1x10 to be remakably able and it's all I'd ever take to open mic's or jam sessions. In fact I take a much smaller 1x6 to most open mics. I've done dozens of gigs with just a single 1x10. I ended up with the prototype and didn't expect to use it but though I have more expensive cabs it is still my go to cab. Two of them would be seriously good gigging set up. That's with the Celestion drivers though, the Ashdown drivers might not work quite so well. The crossovers are designed for that particular combination of drivers too so you could end up with a mis-matched cab and a miss-matched crosssover. I don't want to be too pessimistic though, most drivers cluster around a fairly similar performance level and for all I know Ashdown may have used re-badged Celestion drivers. That cab would suit a range of drivers and you might be lucky. the crossover was optimised for the 110T but it's a very simple thing so it would kind of work and I've seen much worse in commercial cabs. I'm not trying to put you off but if you are aware of the limits of your plan then at £35 you don't have an awful lot to lose and a reasonable chance of success.

I too can see no problems. We had a guitarist who used a Helix which tbh sounds consistently better through the PA than a mic'd up cab or a DI. He used in-ears or an Alto TS10 for monitoring which he upgraded to an RCF310 after borrowing mine. I've also worked with other guitarist using multi fx/modellers and it's been a positive experience all round. Reducing stage volume and using the PA for heavy lifting is the future

Have you developed British understatement She pretty much nailed that and so did the band. I wonder if Led Zeppelin recorded through that mic would have sonded an awful lot better? She's a lovely person too, she thanked the bassist first If you are playing with people like that no-one is going to notice you smiling, and it would be a shame if anyone upstaged her. Just wind her up and let her go.