bootsy666

Sorry if these pics turn out small, I've had to resize them all to upload.

Done! Six 4" ports on the rear and all front ports blocked. I can't seem to upload any photos onto here?

4" wide 6" or more long. Does it matter where they are placed, I was aiming for the bottom upwards? 3 each side.

[quote name='Phil Starr' timestamp='1429900666' post='2756238'] Just so you know. You need big ports because they need to shift a certain amount of air, equivalent to the air moved by all the cones put together. Moving that much air through a tiny hole will make wind noises. The ports are there to tune the cab to something close to the resonant frequency of the speakers. Just putting in random holes might tune the cab to a frequency which is pointlessly too high or too low. You might as well not bother which is why I suggested leaving them out. If you do want to tune the cab and get a bit of extra bass then use ports the size Alex has suggested. 4" drainpipe ( actually soil pipe) is easy to cut and you can fix it in place with silicone or other mastics, even if the hole you cut is a bit iffy. [/quote] Ok. I think for the first time on this project I will use the advice given to me and go with 4" ports. I'll block the ports in the front and only use the rear. I'll have a look at some drainpipe tomorrow and see if it's worth doing. I've found some adjustable 4.5" screw fixed ports on eBay that I can buy if not.

[quote name='3below' timestamp='1429892549' post='2756122'] From a pragmatic point of view, if you do decide to tune them 4" gives readily available drainpipe. This then makes changing the length a cheap proposition if 'bought' port tubes are not long enough. Marshall DBS 2 x 15 that I once had for a while had 2 x 4" ports on the back (from memory). [/quote] Drainpipe? How would I seal it to the surface?

Four 2" in the front and four 4" in the rear. I'll try this and test it sometime next week when the speakers arrive.

[quote name='alexclaber' timestamp='1429881150' post='2755950'] You can put the ports wherever you like, it doesn't change the sound once you're anywhere other than right next to the cab. The Acme Low-B4 has front and back ones. On our Super & Big 12XN cabs we have them at the front whilst on our Retro 10CR cabs we have them at the side or on the bottom. [/quote] How do they sound when stood next to one? I find that un like most people I can realy hear the diffirence between front and rear ports, I think that front ports sound a lot better for the style of music I play. I'm going to try four 2" ports on the front, one between each set of speakers. And four 3" on the rear panel across the bottom with long tubes. Or maybe they should be 4"?

[quote name='alexclaber' timestamp='1429371641' post='2750912'] You're only using a 400W amp with them and the drivers will each handle 250W thermally - so 2000W total. Heat definitely isn't an issue, whatever Celestion say! You can definitely rear port them but you need to get the size/lengths right or you'll end up tuned too high which will kill off your deepest lows. As soon as you make the holes bigger you have to add length to keep the tuning frequency the same. [/quote] I'm still in decided on front or rear porting after reading all the useful advice on here? I Might break the rules even more and try front and rear porting together. I've never seen or heard a cab with both, and I'm guessing there's a reason for that? I think I will find some trong thick foam and use it to plug some while testing to see which ports I should keep?

[quote name='VTypeV4' timestamp='1429827094' post='2755453'] Can we have some more pix, please? [/quote] Soon. I've made a few alterations to the ports and apearance. It's just finding the time to get it done, I'm mega busy at work right now.

[quote name='The Badderer' timestamp='1429834030' post='2755497'] That looks like a whole lot of fun!! Go for it bootsy! I'm in the "Do it because it's fun and you'll learn a heap from doing it" camp. Think the cab looks great and will definitely be a major talking point at any gig, plus it's obvious your heart is really in this project and you should see it through. Having seen how sometimes threads like these in recent times can go a bit south, I just feel it's important to mention that when people like Bill Fitzmaurice or Alex Claber or anyone else at an "expert" level comes on to a thread like this and contradicts what you are doing, try to remember that even though some of the advice may sound a bit harsh or critical, they are giving professional advice for free that they don't have to give. It doesn't mean that they should be treated like Royalty and we should doff our caps to them, but they don't really have time to spend composing their posts to give it a non-offensive feel. We do need to remember they actually know and understand what they are talking about and giving that advice for free. I think it's good that they offer their honest advice as there is no point them coming on a thread and cheering you on as you spend a fair chunk of money, whilst they might chuckle to themselves thinking "this will never work". I think it's really good that they are offering their honest opinion, whilst their idea of what a cab should be might differ greatly from what you have imagined with this project. It's great that you are seeing this through and wish i lived close enough that I could come and hear it and feel what it's like as my internal organs all rupture at the same time! I really hope this hasn't come across in a patronising way, I just thought it was important to say in a friendly way.... God forbid this thread would go in the direction of the fabled "compression" thread of doom! [/quote] Much appreciated mate. The advice on here has been very helpful.

[quote name='Phil Starr' timestamp='1429513615' post='2752003'] It isn't true. As far as the speakers are concerned the valve watts are the same as any other watts, a measure of the electrical energy going into your speakers, nothing magical about them. The reason for valve amps sounding louder is well understood, simply put valves and transistors can both be driven into overload, the loudest bits of your bass are easily 20dB (100 times) the average you are playing at so if you are playing an average 10W then the loudest bits will be distorting. With valves the distortion sounds Ok and you can turn the amp up even more, with more nice distortion. Transistor/solid state amps sound poor and worse as you turn them up from this point and so in practice you don't. The upper power is still 200W or whatever but the average power is reduced because of the horrible distortion. I'm probably one of the 'experts'. I hadn't commented because the advice you've been getting is good. Now I'm on I cant resist any more Your design is bonkers from a practical and technical point of view but looks like fun. Your speaker will work though and give you a different sound. With all those cones it is going to be very loud and very bassy sounding. There wont be as much deep bass as high bass but with a restricted top end and a fairly sizeable peak around the 100-150Hz range you won't be disappointed with the perceived response. You really aren't going to have to worry about power handling though 200W through these guys is going to be too loud for the band and audience to bear in any enclosed space.you are likely to play. That's 25W per speaker which means they'll probably outlast you and certainly outlast your hearing! The only poor advice is from Celestion, I wonder if you spoke to the Saturday staff. The ports will make almost no difference to speaker cooling as the air in them just vibrates back and to at most frequencies, very little air flow will occur when they are being used so no worthwhile cooling will happen. The ports are there to tune the cab, since you've not done anything else technically correct why bother with an added complication which won't cool your speakers. I'd block the ports. If you are going to keep them then put them on the back and make them big, at least as big as Alex (I think) said. Lots of 4" pipes. Some 'experts' forget that a technically optimised speaker isn't necessarily going to sound the best. You are going to end up with a huge speaker that will sound like almost nothing else but be a talking point at every gig you take it to, people will come just to see the mad speaker, not a bad thing for any band. you could doubtless achieve a very similar sound at a fraction of the cost with a couple of 15's in a well designed cab using eq for the tone and a more powerful amp but this is a fun project which will give you a massive retro sounding cab, if you can afford it and are happy to move the thing then enjoy. Just because you can [/quote] Thanks!

[quote name='planer' timestamp='1429391151' post='2751089'] This is turning into an epic build thread :-) I can't wait to see and, given our apparent proximity, probably hear the finished beast! Good on you for building something wild, it's a corker. [/quote] Do you live near shoreham?

Besides technical stuff, I've brought some good quality black leatherette, I used the same stuff to wrap my vba400 in and it came out quite nice. I did plan on using it on the front baffles only before the speakers go in, but I'm having second thoughts now. I guess I could always remove it if it doesn't look right.

[quote name='skankdelvar' timestamp='1429373794' post='2750937'] More. Just more. Of everything. Actually, I agree the VBA will be fine. Just that a handmade, Savile Row Gentleman's rig should [i]probably[/i] include a suitably excessive head. Preferably about six foot wide with a strobing faceplate and a Martin-Baker ejector seat. [/quote] Someone told me once that a 200 watt valve amp was the equivalent of a 1000watt solid state. If that's true then the vba could handle a 2000 watt cab, that's one of the reasons for making the cab 2000watts. I currently have a quad of 6550A valves in it, but u also have a set of brand new sovtec KT88 Russian valves sat in my garage waiting to be used. I wanted to hear the 6550's with this cab before changing them tho.

There's an old amp tech who lives near me who's built a few 1000watt tube amps in the past, I might ask him to do me one. I think the vba will be fine, what's the equivalent of 400watts valve compared to solid state?

[quote name='alexclaber' timestamp='1429370143' post='2750885'] Bootsy, a few simple things to bear in mind. When you make a cab smaller per driver then you lose true lows (sub 100Hz) and gain a small amount of upper bass (100-200Hz). Because your cab doesn't have much volume behind each 15" it won't get a lot out of each in the real low but you'll get plenty of output in the 100Hz+ region. Bear in mind that if you're downtuning to A your lowest fundamental is 27.5Hz, first overtone 55Hz, second overtone 82.5Hz etc. However, because your cab has eight drivers working in unison and the total size is large, you'll still get a lot of output in the sub 100Hz region - you might need to back off the 100-400Hz region with your EQ so your low-mids don't overwhelm your true lows because otherwise you may end up sounding just like a big guitar rather than proper doom bass. Regarding the ports, if I were you I'd plug them. They're too small to work without making chuffing noises once you're cranking and the more you plug, the worse that will be. [/quote] This is the kind of stuff I need to hear! That's very helpful man. Celestion have to me that the speakers need venting for heat exchange? Is it an option to block all front ports and install lagers ports in the rear? I used a cab with rear porting once but didn't like the sound of it.

[quote name='SubsonicSimpleton' timestamp='1429368716' post='2750866'] I don't think anyone is hating - if you like the sound of the celestion TF speakers in the Matamp cab that's great, but if you put the same speaker drivers into a cab with a different internal volume and porting arrangment then they won't sound the same as they did in the matamp cab you liked. Regardless of what you want to acheive sonically, the laws of physics affect all speaker cabs in the same way - it might be a bit of a shock to the system to unveil your design and receive criticism, but considering how far you are downtuning, surely the low frequency response of the cab is important? [/quote] I did ask a question about mixing high and low frequency speakers in the v shape of the baffles, but I was just mocked rather than given an answer. It would have been nice to have had an answer to that question tho.

[quote name='3below' timestamp='1429369264' post='2750872'] I suspect some classic cabinets would probably be sub-optimal when subjected to computer aided design - I am particularly thinking of the Acoustic 360 that I once owned. Blocking off is a good pragmatic solution. If you find you need larger ports they can always be put in the back of the cabinet. [/quote] Thanks, I'm going with 4 ports and blocking the other 4 to start with, if need be I can just unblock tye other 4.

I really only wanted advice on venting the speakers, mostly for heat exchange. I was thrown a bit of coarse by all this, I've gone back to my original plan and TF speakers. I like the sound of them, I've tried them in a pair of matamp 2x15's. I've made 8 ports of 2 inches each, one for each speaker, if this ends up being too much then I will block some off?

[quote name='Jecklin' timestamp='1429352913' post='2750669'] @bootsy666 I LOVE the look of the burnt wood on your bass and guitar cabs! (I'm a big fan of raw wood cabs anyway) Your back line would look amazing in less conventional venues as well. Ie where an audience can really see the stuff making the noise. Have you got some other gig dates lined up? Not a judgement on anyone at all - but I'd hazard most commenting here have no comprehension of the sonic context your band operate in. I'm lucky enough to have seen Sunn(0))) at the underworld 11years ago, having gone with friends but knowing nothing about the music. It certainly changed my perception of amplified distorted bass They weren't using much of the PA system [/quote] One of my favourite bands!!! And in a great venue too.

[quote name='M@23' timestamp='1429352295' post='2750661'] How much amplifier will you need to power this thing? Will it work with a standard 500w class D job? [/quote] I willbe running this with a marshall vba400, x8 KT88's.

I value all of your advice on here, negative and positive! I'm not going to reply to any of the bitter comments either. This cab is a radical design, I knew this before I started it. I did do my homework before starting, and decided against the modern designs that computer programs claim are the best, instead I went with the same idea as the early sunn cabs that have been very successful. Maybe the haters should listen to my band? There's no clean bass, I play through an excessive amount of fuzz and distortion, my strings are 175 gauge, and tuned between low G and A. Nothing about my style sounds clean tonal and correct. And I would like to say that I am a fan of matamp bass cabs, they have huge mid range power which is what i am looking for, and guess what speakers they use, celestion Tf's!!! Apparently only for PA and would sound sh*t in a bass cab? And Bill... If this cab sounds great, would you print your words on to paper and eat them?

Here's a good question. If there were two sets of four speakers in this cab, both same impendance and watts, but different frequencies. Four of the the same in the centre four holes, and the other four in the top two and bottom two, with a horizontal baffle inside dividing the eight speakers into two sets of four, would it sound better?

[quote name='Matt P' timestamp='1429175504' post='2748712'] ok, then my calc comes out at about 65kg empty, which would be well over the 103kg of your old cab when you add the drivers, personally I'd be looking at the designs by Bill Fitzmaurice or the fearful designs, 1x15 or 2x15 with the eminence speakers. Matt [/quote] The basson weighed nearly 230lbs! I swapped the speakers for green label neo's, it's easier to move now.

[quote name='HazBeen' timestamp='1429132750' post='2748469'] Eminence 3015's would work. Although the maths do not lie, the cab may be pretty well suited for the sludge/stoner I have just enjoyed checking out.... Although a 4x15 straight in the cab you have just built and then another would work better.... Interesting link for you to read. http://www.markpercy.co.uk/cabinet.htm [/quote] That's an interesting read. I did think about boxing the speakers off, but didn't because I needed to keep the weight down.