Phil Starr

That's great, the whole point of a self build for me is that you can take control and customise. To get that response I raised the tuning to 55Hz so with two ports you need them to be around 15.5 cm

How far have you got with the build? The port/s will need a bit of adjustment for this speaker. I think the 12PR300 is a good choice for this cab, normally I'd say spend teh extra for the 12PR320 but it really needs a bigger cab to get the best out of it. The only thing you really lose is that the excursion on the 300 isn't as good. You'll end up with a really lightweight portable cab though. One thought though is that I think Stevie's 2-way BC112T mk3 might suit you best of all, maybe even making the GK redundant. It's not the extra top end of the tweeter but the smoothness of the midrange response that you might like. If you went with the 320 you could use that in the new cab. However the 300 in the small cab promises a really lightweight portable solution.

I ran one other speaker the Fane 12-300 Pro because it is on special offer at the moment, and in stock at Blue Aran £64.88. At this point I need to know what you want, is cost the driving factor? Is light weight more important? Do you prefer an old school coloured sound or is clean more important? What are you going to use the speaker for, mainly practice or regular gigging once that returns? How powerful is your amp? This is the Fane (solid line) compared with the 12PR300.

OK I've had a quick look. This is the two Faital's the 12PR300 (green) and the 12Pr320(purple) in the 30l cab with the 12CMV2(red) for comparison. The box is quite small for pretty much any 12" speaker so they all show a hump above 100Hz. The 12PR300 has the flattest response and the Beyma has the biggest hump and is about 1db louder below 100Hz than the others, that's just noticeable. the 2db hump centred on 120Hz is very noticeable and some people like it. The flatter response of the 300 is nice, it will mean it is going to sound cleaner and will take to eq more easily. They aren't terribly different, the bass response is determined by the size or the box which is fairly extreme or a 12. however they all pass my test o the -3db point being below 80Hz meaning they will all give a decent response of the crucial 2nd harmonics of a four string.

Hi Martin, I haven't modelled either the Faital Pro 300 or the 320 in the 30l cab. I'll have a look sometime in the next couple of days and let you know what I think. I did look at the m both in another context and concluded that as a single driver I preferred the look of the top end response of the 320. Anyway Until it's been modelled I'll keep my powder dry. I'll also look to see if there are any other cost effective alternatives.

Hi all @carnabass has saved one of our old designs and is sending me some of our original material as pdf's. We lost a lot of photos of the builds too as Photobucket and other sites disappeared. Do any of you have any old material saved anywhere that might be useful, it could be of your own build even. If you have can you pm me I will go through all of the posts in the long threads but I already know a lot of information has disappeared and screenshots are great but I'm losing some quality by doing everything that way. I'm working to get my micro-cab build up this week. It would be good to get some comments up there about the format so I can learn from mistakes and polish up the other designs as I get to them.

Yeah big call out for Gear4Music. they let me know they aren't expecting any TC Elf stocks in soon. I cancelled the order and they dealt with that promptly. After all the problems with DV247 I'll definitely be looking to G4M in future.

Hi @RhythmJunkyWelcome to BassChat

Ok good question I'll give the answer in two parts. The volume of the cab is very important as it has frequency dependant elements and non-frequency dependant effects. It acts as a mass on the back of the cone, a spring and a sponge and that is in any speaker cab. In a ported there is the added complication as it acts as part of a tuned couplet with the port. The conventional theory on speaker design changes all these things into resistive, capacitative and indictive elements and crunches all the elements of the cab and the driver to balance them all out into a workable cab. The volume and the tuning of the cab have all been calculated to match the speakers we use and then we've built and tried them to make sure they meet the specs we started out to achieve. The shape of this volume matters far less than the volume and tuning, the differences caused by shape will be less noticeable and some will be below our ability to detect them. The real issue with changing the shape of the cab are resonances. It's quite possible for a resonating panel to put out as much sound as the speaker and you can both hear and measure resonances. There are also resonances in the air of the cab and in the port itself. The frequency of the resonances are set by the dimensions of the panels, their flexibility and their masses. If you are sticking to plywood as in all our designs then it's only the dimensions of the panels that are changing so you'll be shifting the resonances upwards with smaller dimensions and down with longer ones. The worst thing you can do is to repeat dimensions so panels all resonate at the same time. The worst shape is a cube and the ideal is one which sticks to the golden ratio (roughly 1.6:1) The advantage of using a ready made design like ours is that a lot of this work is done for you. In the later designs cab resonances have been looked at and bracing suggested where needed. The joy of a self build however is that you can personalise your build and let's face it there are only a limited number of options open to you if everything is to fit in. You'd probably have to be very unlucky to hit a truly awful resonance and so long as you know to look you can always find the resonances with your fingertips and knowing about them gives you the chance to deal with them by bracing the panel concerned.

I think it is a question of a design choice. You can design a flat response speaker and then use eq/modelling to get the sound you want and that is how the Mk3 was designed. Or you can decide to 'voice' the speaker to make a satisfying sound 'out of the box'. Different people prefer different approaches. I don't think it's about right or wrong, for me it is abut what works. It isn't really about efficiency or wasting power. the blue line (higher tuning) shows an extra 2db at 100Hz and the red and extra 2db at 40Hz, so which is louder? They are both the same sensitivity for the majority of their response. I designed the MK1 to give a satisfying result for a first time builder and gigged it extensively to check that it worked in a band situation. The secondary aim of these threads is to de-mystify cab design, there are lots of these little tweaks in commercial designs where the compromises are made for you. When it comes to something simple like this where blocking a couple of ports lets you hear the difference at home and decide for yourself then it's a perfectly sensible thing to ask and try out. @Gottastopbuyinggear might well decide the decisions I took all those years ago weren't right for his needs today.

Bugera Veyron? Meets your spec except for price. It's only 800W not 2,000 but it is 800W

Hi John, I wonder whether this belongs in an amplifier thread. In many ways this looks like another amp like the Gnome/BAM/Elf, if so it's a remarkably cheap option but it's roughly the same size and power output. As it happens I'm sitting here looking at a little power amp board based on the TDA8954 which will give this sort of power given the right voltage, it cost £10.35, I bought a preamp at the same time for £6.54 of course it needs a power supply and a case but it isn't hard to see how cheaply switch mode stuff can be built. Last year I repaired a Behringer active monitor with a replacement plate amp. That cost me less than £100 and that had two amps in it, nominally 250W for bass and 50w for the tweeter and that included most of a case and the power supply. I suppose I'm saying it can be done and if you get Thomann's three year warranty why not try it? I'll be mainly running my Gnome of a B1 too.

Yes i remember gigging with the prototypes, they could be overwhelming My drummer at the time once repeatedly asked me to turn it up, so I did, at the end of the first set he said 'I couldn't hear my effing snare drum' covering one port won't be enough to make a real difference try going down to two. This is what it will do to frequency response The trouble is that it also affects power handling and potentially port noise. this is power handling. 180W @70Hz isn't too bad but you need to know

Some of you will have noticed that I am (very slowly) trying to archive the BC designs so that people can go on building them. What has become apparent is that many of the parts have become unavailable though substitutes are always coming through as well. I'm going to tweak the designs as I go and one of the things I will do is move to only using standard building pipes as ports as the pre formed ones only seem to have short runs. The horns too have short lives it seems. I'll double check but I think the Mk1 was very slightly bigger than the Mk2/3, Both nominally 50l but I allowed slightly more 'extra' space in the Mk1 to allow for extra intrusions into the cab. So long as you use the Mk1 ports in the Mk 1 cab and Mk2 ports with Mk2 cab it won't be an issue. The shape was a result of requests that the cab should take an old heavy iron 19" amp with no overhang. My intention is to do an 'easy build' version of Stevie's mk3 shape cab as a revision for the Mk1 and that will go up eventually. In the meantime you can build the Mk3 shaped cab without a horn if you want. Retrofitting a horn has always been an option though you'll need a new baffle as I didn't leave enough space for the specified horn in the Mk1. The horn/crossover for the Celestion 1445 version of the Mk2 is still up on the thread and that was my favourite combination. Stevie is our crossover expert but I don't think changing the cab will make a significant difference at the crossover point but changing the horn or compression driver will as he pays a lot of attention to anomalies here and is very careful about the matching of horn and driver . @Gottastopbuyinggear I'm not sure why you would want to build a Mk1 with a higher tuning? Stevie and I differed over the preferred tuning and it is possible to come up with a series of tunings that will work well each achieving different compromises. There's a lot of discussion about it in the original thread I believe. The effects are complex and affect power handling, excursion and the shape of the response well away from the tuning frequency. We did listening tests too before we settled on the recommended tuning. There's lots of good reasons for tweaking the tuning but it certainly isn't as simple as taking out a bit of bass by tuning higher. Let me know what you are trying to achieve and we can see what the options are, you might be better off reducing the size of the cab for example. There's a lot of psychoacoustics involved too, just adding the horn will make your cab sound less bass heavy.

This is possibly the bit to look at first. The way to keep the vocals 'pristine' is to keep the level of bass reaching the vocal mics to an absolute minimum. What you want is for the audience to hear both the bas and the vocals and everything else clearly in exactly the right amounts. That's not about keeping it out of the PA it's about getting nice clean signals to the PA. The perfect solution for vocals is no backline at all, no sound bouncing around the stage and being picked up jumbled by the vocal mics. Ideally use in-ears but next best thing use your wedge monitors for bass. If you have to have a bass amp on stage use it for your own monitoring and keep it as low as possible. As to the new speaker without technical details we can't really tell you what sized cab sealed or otherwise would work well. Can you get the TS parameters for the speaker?

The marginal cost of a combi that would keep us all happy isn't that great but Neutrik would want their cut I guess and £10 on a £120 amp is significant. You'd think that Trace would want to distance themselves from their much cheaper competitors though.

A combi socket would be nice. I grew up on jacks and really don't mind using them on something that is relatively low powered, You can also buy jack to Speakon adaptors and I have one in the gig bag I my Gnome is in so I can use a jack/jack lead and still connect to a more conventional cab. I don't find it a problem. I've screwed my amp back together so can't help you with advice but most sockets are wired to the boards directly making a socket swap problematic. Is this an aesthetic thing for you or a worry about current handling?

So there's the sort of generic resemblance you'd expect. The switch mode power supply at the bottom looks very similar indeed apart from the heat sink. I quite like the toroidal transformer in the BAM but the component layout looks just about identical. The power amp is very similar too, lots of detailed differences but the same architecture but that's as you'd expect. You can clearly see the two amplifier chips bolted to the finned heatsink in the Gnome and sure enough there they are again in the Bam bolted to the big bent heatsink there. They may indeed be using the same chip, I'm not so keen on that inductor on the BAM which is there for rf suppression on the output (the untidy copper winding about one third down just right of centre) it's much tidier and more substantial in the Gnome. I wouldn't say they were built in the same place though, just the same chips in very similar configurations.

OK I can't resist. Eight screws later. The internal anatomy of a Gnome.

The input impedance is 10Mohm so, yes it's MOSFET but that isn't really a special feature nowadays. Also not in the advertising is that there is apparently some compression built into the input stage. It's mentioned briefly in the manual that came with it and there is a bit of crunch that comes in when the signal lamp starts flashing, I've no idea how Music Tribe (Behringer/TC) work but I doubt they share components with Warwick. More likely they share the same chip set produced by a third party. The big chip manufacturers release all sorts of application notes with circuits in, including board layouts and development packs. Certainly for the power amps manufacturers use mostly what they are given. The pre amps may vary but if you squeeze gain,bass,middle, treble and master controls into the smallest possible space you are going to end up with things that look very similar even if slightly different frequencies are used in thee controls. Behringer have also been known to um... make 'tribute' amps. If I open mine up I'll take some photos if someone wants to take a BAM apart. I doubt they will sound much different as they are pretty much flat response amps.

That won't be a dead cut off frequency, probably a -3db point (or sometimes manufacturers use a -6 or -10db point). The roll off is anything between 12-24db/octave. Sealed cabs roll off more slowly usually but there will generally be less bass anyway with a sealed cab. The designer can manipulate that a little, I forced the -3db point to 70Hz with my micro cab at the expense of a slightly faster roll off. It's much more complex than a single variable but one trade of you can make is making the cone lighter trading efficiency for a higher roll off point. you won't get rolling thunder out of a cab if f3 is 90Hz but most of the information is in the frequencies above 80 hz so it will still be useful. Placing it on a hard floor and against the wall or even in a corner will help add some of the bass back in.

Yes that's pretty much it Al. Limited but fool proof which is what I was looking for. And yes you can have six phones all doing their own mixes or you can do it for the technophobes if they need it. The reality is that once they have their mix you just save it. The best bit for me is the software, the simple menu structure and the sheer reliability/ease of use of the sliders. One tap on the screen gives you 1db adjustment and as most of your adjustments are of that order it's hard to completely mess up the mix or your playing. It's actually easier than physical sliders in practice, which was my only worry about going digital. You can trial the software for both by just downloading for free and it was trying that which convinced me the M18 is just more sorted for live work. If I was a sound engineer mixing someone else FOH I'd probably have gone for the Behringer but I'm a bassist standing at the back. having said that any of these mixers offer you so much more processing power than you'll have ever had on stage before. To be accurate the Behringer does offer multi track recording but the M18 doesn't, just the stereo mix. If I do decide to record our live performances multitrack I'll probably go and buy the X18. In the meantime the M18 does all I need and if I sell it I'll make most of the cost back I can see a place for both or maybe an M18 for pub gigs and an X32 for posh. The M18 though is the perfect engineering solution for my needs with 4 or 5 piece bands playing mainly pub gigs

I'd say the chances of complete success are fairly low. The speaker has to match the cab to get the best out of it. The cab is, or should be, matched to the speaker in volume and tuning. Then the speaker also has to be matched to the horn unit and the amplifier and the crossover. The chance of this all slotting into place by luck is fairly low to zero. The other issue is cost, as original the Headrush has value which you'll halve if you try and sell it messed with, even if you think you've improved it. A good quality lightweight 12 could cost you £130+. Sell the headrush and add those together and you could probably buy something better than you have. I'm all in favour of people experimenting as you'll learn lots but it's probably not the project to tackle.

Just a quick update, I finally got to use the prototype in anger this weekend. A noisy open mic with around 50 people in the pub. I've done a quick review over in the Warwick Gnome Thread as that's the amp I used with it. I didn't know it was happening but the host was posting on FB so this is a snippet recording on an iPhone House Jam Cab Everything set flat with a bit of compression/overdrive on the input and maybe 2-3db left on the output Warwick Gnome into this single 6" 8ohm speaker. It's not hi fi but a decent set of headphones should give you an idea of the volume you can achieve with this tiny cab