Phil Starr

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

Just that really. We are in a great position to cope better than most. We have a community here to talk to and something we love doing but never get enough uninterrupted time at. I'm planning to sort out all my hundreds of chord sheets and tabs and get them to our top floor, make sure I have plenty of rechargeable batteries for my zoom and my best headphones at the ready. My three best basses will go up and the computer and an mp3 player, then I'm entirely self sufficient and can play without waking the street. For fun I'm intending revisiting songs I haven't played for years. Our band wants to go down a soul/funk route, something that I've never played, it was going to take me months to learn a new style with a few techniques to add to the flimsy armoury I currently have. If I can find time my music theory is shocking, I need to work on my speed, hell, I could even learn the dusty bit of the fretboard. Two octave runs..... (I wonder if I can fake a cough and get extra isolation time ) For me bass is all the 'wellness' I need. The man cave my safe space. the best anti inflammatory I can get. Guilt free time on Basschat as well. What will you do?

Just to back up what has already been said from experience the 935 (which I use) is more forgiving about mic placement for idiots like me who can't stand still when playing and singing. I think the 945 actually sounds a little better but I only do bv's so no-one is interested both are good mics anyway. I've found that the Shure Beta 58 sits somewhere between Cardiod and super-Cardioid in terms of pick up.

Yes Nice that you get two Thumpinators built in as well

Mike I think you are going to cancel anyway but don't be out of pocket, I'm happy to chip in if you are

Hi, I haven't kept anything from the design process, everything should be in here The reason for four ports is the 'easy build' bit. I wanted something that could be cut without specialist tools and easy to source so drainpipe and a hole saw were chosen. I built one prototype with a slot port but couldn't build it without using lots of clamps that most people wouldn't have at home, so again that didn't fit the 'easy build' criterion. A single port with the same area would be better in terms of port noise if you can cut a bigger hole accurately. The other thing is that this design was specified to match a 19" rack mount so the dimensions can be changed if you want to have something a little less blocky in shape.

John, (Chienmortbb) has bought one and has been playing around with it. It looks like a better buy than the SM212 and it models well in the 50l cab. Coronavirus allowing I'm going to meet up with John fairly soon so we could try it in the Mk 1 cab if you want to wait for a listening test. However I'd have to say the 12CMV2 looks a real bargain and I'd have no reservations about using it other than the fact I haven't actually tried it. I gigged the SM212 fairly extensively and still do from time to time. Playing with a couple of the MK1's is to drown in a sea of bass. If you decide to go ahead and are happy to do a build diary I can help you through the build and maybe tweak the cab a little.

Don't you remember the great vinyl crisis during the three day week? I reckon my current stocks of loo roll will last until 2045

Spot on about the only being completely in phase at one frequency. These were designed in the 1960's way before Thiele and Small came along in the 70's even than their academic paper took a while to permeate into the design of instrument speakers. I was designing and building speakers in the early/mid 70's and it was more craft than science. Development involved a lot of listening and testing and even the tuning of the port often involved a lot of trial and error to get right despite Helmholtz resonators being fully understood. My best selling design (mainly I did custom builds) came about completely by accident. I was attempting to build a small (by 1970's standards) cab with rear horns when I needed a couple of cabs for a gig quickly. I bodged together the half finished cabs with a simple straight horn rather than the folded horn I'd been intending. It sounded great with a nice smooth punchy bass ideal for disco and was way quicker to build than the 'proper' design I'd intended. W designs were very popular at the time which was probably why it sold. I surmised that it had a broader flatter tuning than a straight reflex port but I never investigated. Hell I had a nice sounding easy to build design people liked. There were many attempts to get a broader output form the ports at the time, changing the Q of the cab. This may have been at the back of the mind of the designer but personally I think it's just a support for the grille and it sounded good so they kept the design. A bit of me still misses the hours of fiddling with a cab and hours of listening while you tried to get the 'best' sound you could. Not very scientific but it might be why so many people like vintage gear. Anyway that's a lovely build rubis, I hope you get a lot of pleasure from it.

I'm still finishing off a roll I bought back in the 70's