Phil Starr

yep 18mm is good for a cab, better if you don't mind the weight, you have more than enough for one of these

Hope you like them The Beta's have a really prominent peak between 1kHz and 4k. they are also slightly underdamped so will give you a prominent peak around 100hz in most practical sized boxes, so will end up with a bit of a smiley faced eq baked in. the Beymas are similar but it won't be so exaggerated and you'll get a little more deep bass at power with the extra excursion. It's the kind of response I like in both cases but £15 per speaker makes it a no brainer.

I've made up all sorts of cabs with off-cuts, they all work and are a great basis for tweaking later on. This is an 8" cab too so the forces on it won't be excessive. At this stage I'd stick with what you have and see what it sounds like. If you turn up the cab really loud you can feel the panels vibrating with your fingers. Find the worst spots and put a length of dowel across the cab to damp the vibrations at that spot, by the time you have a couple of dowels in place you'll be pleasantly surprised at the damping you've achieved. You can go on doing this forever and there are other panel damping techniques too. The more wood you add the better it should get but you are adding weight all the time so there's a compromise. For the record MDF is a great material acoustically but heavy and doesn't cope with damp, chipboard (particle board in the States) is pretty good, medium weight, but has to be the right grade and is difficult to finish well and isn't very tough. Hardwood plywood is pretty tough and lightweight so great for portable cabs. Softwood ply is, well soft, so you don't get the toughness you want. Your cab is looking fine to me so get it finished and see what it sounds like, we can talk you through damping when you get to having a working cab

The type of ply you have chosen isn't the best choice for a cab, It's really made to be a cheap material for shuttering on a building site for forming poured concrete. You won't get significant stiffening by treating the surface, so why do it? I'd imagine the Tuffcab would take to the PVA with no problems but try it on a piece of scrap first. The Tuffcab would be better just applied straight to the wood though. If you want to stiffen the panels then you'd be better of bracing the cab, the simplest way of doing that is to run pieces of timber across the cab gluing them in place so that the opposite faces are joined somewhere near the middle of the panels, slightly off centre is best and make sure the braces don't get in the way of the speaker or reflex port.

they all take the same terminals

I don't think there is a lot of point in coating the inside, the only reason to protect the wood is that being soft it may dent but the paint finish is fairly flexible. The Duratex should offer fair protection to the outside

Thanks, I'll investigate

Hi Stevie wondered if you'd reply. @EBS_freakIt's fairly normal in crossover design to do some equalisation so to do some of the same thing in DSP as you would in a hardwired crossover doesn't look like 'cheating'. I've always looked for drivers that are flattish especially in the crossover area and it looks like this is what RCF are saying they use as a starting point. I'd also use some sort of dynamic limiting to protect the drivers and they put their hands up to that too. Limiting would be more linear in DSP than putting an auto vehicle bulb in series with the horn driver which a lot of old PA speakers did I'm reading this as they are trying to make good speakers with decent components and making pragmatic decisions about how to use DSP rather than lot's of processing to give an 'enhanced' sound to sell the speakers in the showroom. I guess where any of us judge the point where equalisation becomes enhancement becomes a bit of a semantic point. You can do so much with DSP. I have to say I've listened to a few RCF speakers and they sound more honest and less congested than most of their rivals in the same price range. I think their compromises are mainly well judged.

As Bill has said those drivers are overkill, not to mention the weight! They are way cheaper over here though. I think you have used the SM110's before but these might be worth a look https://www.bluearan.co.uk/index.php?id=BMA610CVM28&browsemode=manufacturer I know @Chienmortbb has tried the 12" version and is fairly impressed.

hi Paul, might be worth checking out this thread, I think it still has details of some of the prototypes so there are a couple of options there as well as the final design but you could always ask @stevie via pm. The biggest problem is the crossover, commercial ones are generic and will work but won't match your particular drivers together very well, neither speaker will necessarily have a flat response around the crossover area which means a custom design is best. Using Stevie's design could work for the horn at least.

It's good to talk about something other than you know what I don't play upright and I haven't had cause to mic one up for 40years now but I'd think these would be ideal, basically a neutral sounding cab. I would so like to get my hands on them and see what Genzler have done. Either you have huge hands or those are really tiny cabs

I love the design of those cabs but have yet to hear them. It'll be a while before you get to gig the new one but in the meantime a review would be good.

This will end and you'll be back together again, if you are anything like our band this is the chance to refresh your set list, if you all learn a song a week it'll give some focus to your practice. mind you with the lack of focus I'm also learning a load of songs the rest of the band don't like, I'm also looking to extend my range, I love Soul music but there's quite a high entry hurdle when moving from pop/rock this is a chance to build up some new skills. Playing regularly with covers bands can be a bit of a treadmill even though every gig still gives me a bit of a thrill.

Off centre is better but of course there isn't much chance of that with a 20cm speaker in a 30cm cab. You could make the cab 20x25x40 or some such variation and putting the port directly in line won't be an option as it will probably long enough to touch the speaker. Port placement at the back isn't a problem. For practice I wouldn't worry too much about excursion. You are likely to be at modest levels and because of the placing of the pickups on your bass there isn't a lot of fundamental there anyway. I think you've misunderstood the computer model, the cone will be moving as in the excursion graph, it just won't be making much sound and will be 9dB down. That's a characteristic of all ported cabs. Below tuning they effectively just become an open box with nothing to stop the cone moving other than it's own suspension. Your amp may be limiting things at that frequency though and it's only sometimes a problem. In your own room rather than a gig you'll hear if the speaker is stressed. All this is normal

Assuming you have put the data into Winisd correctly then what you end up with should be close to the predicted response. When manufacturers rate their speakers frequency responses it is only really ever a rough guide, the bottom end is affected by the cab they do the measurements in, often if you dig into the notes they will tell you how it is measured, They may even have just calculated a figure or used F3 as the lowest frequency. In your cab it will be different. At the top end it becomes subjective, The cone will break up at higher frequencies and the response becomes uneven, sometimes very uneven. Sometimes they give the -3dB point sometimes -10db, sometimes something else. This speaker will make a sound at 4khz and much higher too. It's easy enough to make an 8" speaker with decent output at low frequencies. A heavier cone and soft suspension lowers the resonant frequency, what you lose is efficiency. Ultimately you can't have loud, deep and small. If you look at 8" PA cabs you'll find they come out at around 113db maximum output which is what winisd is telling you this will do. There's no reason this won't sound good but it's going to do so at practice levels. Build your cab and enjoy

Stevie has reminded me, yes we did check the tuning

That was certainly the case with the 50l cab Stevie, I think it was the first time we met. I felt a warm glow of smugness, then when I got home I realised I'd fitted the wrong ports 🤔. I'd been experimenting with different tunings the night before. I can't remember if we tested the 30l cab. For anyone following this computer modelling gets you quite close but there are things it doesn't take into account. The cab itself has an influence QL and the speaker manufacturers specs can be out, the speakers also have a manufacturing spread, they aren't all quite identical. Even the amp you use and the impedance of the speaker leads have a small effect. If you can it's best to test which Stevie does. The BassChat designs have all been tested. They have all gone through extensive listening tests, have been gigged and most of them went through Stevie's measurements.

I made the box slightly bigger than 30l for the intrusions into the box, the ports the speaker and the battens. Then I fiddled with the tuning frequency to get the best I could in terms of response, cone excursion and port velocity. The aim with this one wasn't to get a flat response but to get something usable in acoustically difficult spaces. I didn't test it out live until the week after the bass bash but I'm happy enough with it so I haven't gone on to see what improvements other tunings might do. I can't remember what frequency I arrived at but you could put the dimensions of the ports into WinIsd and it will calculate the tuning frequency for you. All I can say at this distance in time is that it works for me in the country pubs I usually play in.

Hi Vince, the Beyma will still be 350W and just as loud in the smaller cab, in fact with the SM212 power handling is increased at some frequencies. You will lose some bass as described. For my own use I am contemplating building a cab of 35-40litres, I decided in pub venues the 50l cabs are just too powerful in the deep bass region, and I quite like the coloured response of the 30l cab but just a little extra bottom end would be great for me. I also want two cabs the same size a 50 and 30 together does look odd.

One of us is confused, it may be me. The cab in the video is the 30l cab the one drawn three posts up from this is the 50l cab, are you wanting to build the 50l cab or the smaller cab? The dimensions for the 30l cab are in the first post here but I've copied them here the panels for the 30litre cab are 2x 374mmx290mm, 2 450mmx 290mm and 2 450mmx350mm (all 12mm ply) the front baffle is set back 30mm to allow for the grille so internally the cab is 350mmx450mmx236mm. the ports are made of drainpipe/downpipe which is 64mm internal diameter 160mm long

I'm loving my Peavey Minimax, the sound straight out of the tin is great, the tone controls are well judged and even the various baked in eq's are all of the usable and not too extreme variety. Plenty of lifting power too. I find it just generally nicer sounding than my MB Tube. I bought it because I'd dropped my MB and it broke, the Peavey was on offer for less than the repair so I bought it for the half dozen gigs I had booked with the intention of building it into a combo later. I probably won't go back to the MB when I do get round to repairing it.

The only sensible decision Mike, thanks for doing all this.

Done

Master Blaster for me I might re-visit the Steve Harris gallop too, the band didn't notice but I fake it