Phil Starr

OK to come clean part of the inspiration for this was 6V6's build. You can see it here [url="http://basschat.co.uk/topic/200152-1x12-diy-cab-build/"]http://basschat.co.u...-diy-cab-build/[/url] if you see the thread I gave him some advice and the rest he worked out himself. I have a similar cab myself and with both of us happy with the result I have the confidence to go ahead and recommend it to others. So apologies to 6V6 he'd be better off sticking with his own design. So, the designs I am picking up so far are: 2x12, we'll include dimensions for this in our 1x12, for people who only want to make 1 trip to the car. 1x15 I'll probably do next Vintage voiced/coloured cab we intend giving alternative driver recommendations for all our cabs together with any recommendations about modifications needed to make them work well. Some of these will have a 'modern' smooth voice and others a warmer more coloured voice, so you will make that choice. Really compact practice cab You can see Lawrence is keen on that, so he will probably come up with something fairly quickly. I'm also playing around with some designs based on a 6" driver so that might come to fruition Upright Bass cab, sadly my wife would probably kill me if I started to learn upright as well as waste all my time in the shed, but as a design challenge this looks really interesting and is completely new to me, I'd love to have a go but I'd need an upright player close to me to work with. Then there's a few points I'm picking up about angled cabs, reggae cabs and cabs with deep bass extension. I'm toying with the idea of building a 'bright box' to get the sound to your ears which might be interesting, I have a couple of designs I'm mulling over. Designs for more specialist tastes I'd love to do but they will have to wait. We also have a problem with funding this. We can't develop cabs without the drivers to hand. This is fine if we are to use the cabs ourselves but I personally can't afford to buy stuff I can't use. There's a load of other things you mentioned, Stevie and Lawrence have answered some of it. We'll write up a commentary to help others design their own cabs. I won't be making comparisons with anyone else's work/designs. It wouldn't be a good thing to do and we just want to do some technically competent designs that others can copy. If we get hate we won't respond that's their problem. I'm sure we will make mistakes and if people can correct them then it would be great to work with them. It's the joy of open source. We are deliberately starting off with simple designs, Stevie and Lawrence are keen to get on with multiway designs and they will come but I have no immediate plans for anything with a crossover, we'll see how it goes. Hope this helps

Keep all the suggestions coming in. You'll see by the time that it is late, so detailed responses will have to wait until tomorrow but there is plenty of food for thought here. We won't be able to do everything in a single design but we will be able to say what compromises we've made and why.

A small group of us (Myself, LawrenceH and Stevie) are working together on some cab designs which we will make available free of charge to Basschatters. At the moment we are working on a 1x12 which should be an easy build, cost about £150 and will keep up with an average drummer fairly easily. We will go on to look at other designs. We'd like to open it out to you all, what would you like us to have a go at, what designs would you like to see? What would your ideal speaker sound like?

The clue is in the word .A crossover splits the signal so that below the crossover frequency the sound goes to the bass unit and above crosses over to the tweeter. The system will be 8ohms all the way but you can only do this with a crossover and it has to be the right one. Using the horn you suggest will still make little or no difference to the sound compared to not having a horn, it simply doesn't cover any of the frequencies important to bass. The piezo probably comes in at around 3.5kHz so it does cover some of the top end and will contribute a little to the sound.

There's little point arguing about all this. If any of the places you play are places of work they have to have health and safety representatives by law and these are governed by statute http://www.hse.gov.uk/involvement/whatdoesthelawsay.htm. In addition they have to be covered by public liability insurance and to get this the insurance company may impose conditions like PAT testing. It's all mainly due to fire risks, half the fires in the UK are started by electrical faults. Anyone not fulfilling these duties could potentially go to prison for anything up to life if someone is killed. I'd offer little for your chances if you had stuck a few labels off the internet onto your cables should you end up in court. Faced with criminal liability I'd ask for PAT testing, so someone else took the responsiblity. You can't blame the venues. We don't get our gear tested, I'm not being holy about this. We only do a dozen gigs a year and the cost puts us off. No-one to date has ever asked but if they did then we'd have to do it or turn down the venue. It's a bind but it isn't unreasonable or pointless any more than MOT'ing your car. Like an MOT it's no guarantee the car won't go wrong tomorrow but it's safer than never checking at all. The really bad advice is to fiddle the system or to lie. It's probably something we should all do but to cheat the system is to take all the responsibility upon yourselves, Just as you would driving a dangerous car with a fake MOT.

OK to make it clear, there probably isn't a crossover, it's the main cost saving you get by using a piezo. There probably will be a couple of big white resistors and maybe a capacitor just to match the output of horn and bass unit. To be safe remove the wires that run from either the main speaker or probably the amp itself to the horn and any associated components leaving just two wires going to the two terminals on the speaker itself. Don't leave any loose wires to touch anything and it should be safe enough. If there is a problem then put up a photo and we will advise. Bill is right though about the tweeter, There is virtually no energy at all above 5kHz where the horn you suggested using starts, so little or no point in adding it unless string noise is something you look for!

If you just want to monitor on stage then a little kickback combo will do the job. I use the discontinued Hartke 10 for this and it works well. Roll back the bass a touch on the Hartke and you will get the rest loud enough. A powered wedge will do the same with a lower profile but check it is happy with bass giong through it. If it really is just for monitoring then you don't need to carry anything more than this, a 4x10 would be just too much to carry and why have a separate amp and extra wires? However If you are buying something to do this anyway would it be sensible to buy something more versatile? Something you could use on its own if you get to play in other bands where a stack or a decent combo would be more appropriate. It's a choice only you can make; something small and simple that just does this one job, or something bigger heavier and more versatile. I've ended up with both.

Yep, you can't replace the piezo with a dynamic one, they work entirely differently. the piezo has a high impedance that rises at low frequencies to the extent that it doesn't need a crossover. Put in a 8ohm dynamic without a crossover and it will blow at the first loud note. Disconnecting the piezo is just a matter of cutting a wire or pulling off a spade connector but you need to make sure the wire ends are insulated so they can't short out accidentally.

Funnily enough I've been wondering why more people don't offer something like this. The potential for a smaller cab and better handling of real lows is appealing, at the loss of bass efficiency to be fair, but it is all about trade off. If anyone was interested in building something and wanted help with design then it'd be an interesting project. I'd be happy to be PM'd.

Get a little mono mixer like this [url="http://www.maplin.co.uk/p/3-channel-mini-microphone-mixer-l71ak"]http://www.maplin.co.uk/p/3-channel-mini-microphone-mixer-l71ak[/url] others available including ones in stomp box cases.

First of all don't worry about where the controls are set, Different amps have different levels of gain which have little to do with overall volume. Read this isf you haven't already [url="http://basschat.co.uk/topic/3730-gain-power-and-volume-a-confusing-menage-a-trois/"]http://basschat.co.uk/topic/3730-gain-power-and-volume-a-confusing-menage-a-trois/[/url] If the bass was too loud then it is loud enough. It isn't extra watts you need. I'm concerned that the clipping light is flashing though i do know some amps are set with the light more sensitive than others so check the manual. I don't know the Peavey amp so I'm not clear what the light signifies. One explanation may be that you are using a lot of bass boost. This won't make the amp louder as we judge this mainly by the level of the mids which our ears are much more sensitive to. The deep bass is what eats the power though and just a touch (3dB) of bass boost will demand twice the power from the amp. Bass boost to 3 O'Clock and you might be asking the amp to give 4x the power. This might be a problem. I'd live with the Peavey before you rush out to change everything. Can you get the tone you want? Have you asked your engineer if the bass was just too loud or was it too bass heavy. It's all but impossible for you to judge your tone from the stage area, you need to be out where the audience are.

Wiring live to earth isn't a great idea and you need to get it rewired. It may even have been shorting out internally and confusing the cable tester. I'd also suspect the Di box if it wont clear. If it was all working perfectly up to then it does ask a few more questions and it is difficult to diagnose without the stuff in front of you. However, if one lead was reverse polarity and you had this on one speaker and the other spoeaker is wired normally then they are out of phase. One speaker moves forward at the same time the other moves back meaning at bass frequencies they move no air. One is sucking the other blowing. This does sound weird, completely lacks bass and that may be what you were hearing.

I wouldn't use linseed oil on a bass, it is too sticky really, and forms a gum as it dries. I like the finish but it is strictly for furniture and cricket bats as far as I am concerned. If you do use it then use boiled only and very sparingly, better still use something made for the job with either a lemon oil or a mineral oil base. They will usually have a mix of oils and a drying agent or two in the mix. May cost you £6 for a tiny bottle but it lasts for use as you use so little anyway. I use Dr Ducks and after 6 years it is still 3/4 full.

It would be a shame to ruin a vintage amp by playing bass through a guitar speaker, especially if it is in original condition. You will almost certainly shorten the life of the speaker by playing bass through it and probably destroy it unless you play at very low volumes. Please don't do it.

The power handling curve is what you would expect, it's the sums telling you what we have been saying in words on this forum. If you look at the max power above 150Hz ish then it is a straight line, constant max power. This is the thermal limit, how many watts of power the speaker can disperse before it overheats. This is, or should be, the rating the manufacturer gives a speaker. At the bottom end the limit is how far the speaker can move, or Xmax. It moves further for deeper bass at the same volume. Try doubling Xmax in the parameters and the power handling will go up on the graph (though sadly not in real life). The big dip comes in as soon as the excursion goes over Xmax. Because it is a reflex speaker this then has an extra effect at frequencies around the tuning frequency. Here all the energy you put in is spent on moving the air in the cab and the port and the cone almost stops moving and gets nowhere near Xmax, so you are back to heat dispersion being the limit.

[quote name='alexclaber' timestamp='1387545266' post='2313174'] I can't say that much because I don't want other manufacturers to catch on to some of what we're doing (I'm sure Stevie is rolling his eyes at this and thinking that it's just more 'hyperbole' and smoke and mirrors...) but we doing things with the new drivers that some of these posts suggest is impossible. [b]I've just had a look through the technical pages on our site to see if any of them can be read between the lines to get a feel for what we're doing [/b]but having scanned through them I see that I have been quite circumspect about what we're doing. Much as part of me wants to go, "ta da! How clever is that?" I shall instead say that post 39 and 40 are on the right track, post 42 doesn't address that unless bandpassed that midrange drivers all tend to have quite unique 'sounds' due to their break-up modes, 10"s and 12"s can have pretty decent dispersion from 1-2kHz with the right soft parts, and post 44's first paragraph states the 'impossible' problem that we've solved, yes of course we've measured dispersion (!), and I agree about passive crossovers. Hope that's not too annoying a post, I would love to say more but I don't think that doing so would be a sensible business decision! (I have noticed that the big PA players are being more and more cagey about what they're up to too, to my great disappointment because I've learnt a lot from their writings). [/quote] Careful Alex, that looks like a challenge to some of us It would be a shame if people did clam up. I don't really think there really is anything ground breaking likely to happen, just a better use of the tech that is available to all of us at a price. I'm fairly confident that within a day or two of getting hold of one of your cabs a few of us here could copy all you ideas, the idea that JBL or even Behringer couldn't work out what you are doing and clone it seems unlikely. I also think you couldn't stop yourself from giving the game away, over the years I think you have been scrupulous in what you put out publicly. Like any decent scientist you qualify your statements so that even when simplifying things for clarity you leave a trail. Having tried to do what you are now succeeding in I hope you do well with the new range. Now to see what I can glean from your website, much more fun than the Guardian crossword

[quote name='bumnote' timestamp='1387564740' post='2313503'] What about the phil jones 5" jobbies? I have graduated to an 8x5 pjb [sometimes with an added 4x5] from an acoustic 360 driving a 2x15 and although its not as loud, I get some great sounds from it. It doesn't lack the real bottom that the ashdown 4x8 I tried had . I also use it in a jam environment where it gets used by other people either with my bass or their own. It projects nicely all round the room. I originally thought it was a gimmick but it works really well. I would love to try on of the big rigs with 24 or more speakers [/quote] This is probably a great example of what I'm saying about compromises. Phil Jones embraces the advantages of small cones, lightweight, good dispersion, clean mids, compact cabs and so on and then deals with the downsides in a unique way and makes the compromise work. I love the idea of a vertical 4x5 'suitcase' and one day I'm going to build myself a vertical 4x6 with the best drivers available to me as an amateur fiddler. It's no problem getting down low, just ad a floppy suspension and a bit of extra weight to the cone. My hi-fi drivers are 5" Focals and don't do a bad stab at the low notes from a church organ so electric bass is no problem. that's tuning not size. You can even get reasonable volume by increasing the excursion. The extra weight and the extra coil length will cut down on efficiency though. You can get this back up by using a more powerful magnet but this adds weight, so you have to balance all these. You can also get some efficiency back by using multiple drivers but again this adds weight and cabinet volume. If you put the drivers side by side to pack more in then you lose the dispersion advantage. Get all the competing issues well balanced and you'll end up with a cab some people love. In this case you get clean, tight portable but with some restriction in absolute volume, as you say in your post. As I am saying size isn't the only factor but it does affect the way the compromises pan out in the finished design.

[quote name='LawrenceH' timestamp='1387489181' post='2312707'] I can't say Ive hunted the earth, but I have not come across 12" drivers that will do +/-10mm clean excursion as measured by any method that also give similar midrange sensitivity and extension as Alex claims for his (and I for one am happy to take his figures at face value). The ones with comparable linear travel weigh a lot even with neo magnets. The dispersion tends to narrow lower down on the long-excursion, big voicecoil diam subs too, which goes back to the original topic - cone construction. [/quote] This is the thing, you wouldn't design a really long throw speaker unless it was working as a piston in the lower octaves and at these powers that means a rigid, and probably heavy cone. If you want a wider range then the cone has to flex, Then if you are getting most of the upper octaves radiated from the middle of the cone you can get reasonable dispersion patterns along with the increased frequency response, What you can't get is both the bass of a heavy rigid driver and the cone handling a wide frequency range at the same time. That's true whether you are developing your own drivers or like most of us trying to pick out the pearls from the commercial offerings. I wonder if Alex ever measured the dispersion of his Kappalite based speakers? [quote name='stevie' timestamp='1387492375' post='2312746'] Yes, I know exactly where you're coming from. To do it properly with a compression driver you need either an expensive 1" (like an Italian one or a BMS) or preferably a 1.4". Then you have to find a nice-sounding horn. Unless you really need that 5-10kHz response, a cone driver will do as good a job, go lower, and be a lot cheaper (if you ignore the cost of the crossover ). I've often wondered what a 2" compression driver would sound like with bass - with the right horn, of course. Awesome, I expect. Tens and twelves can certainly sound really nice in that area also (and some of the Celestions I've tried have sounded wonderful), but they can't get round the beaming problem. [/quote] To be fair there are problems with passive crossovers too. They introduce phase shifts and alignment problems at the crossover points and having a dirty great coil in series with your drivers does affect the damping considerably, not to mention the problems associated with saturating the inductor cores at high powers. Most of my serious development came when I was designing hi-fi cabs and I came to the conclusion it was better not to crossover at all in the 1-4kHz range as crossover distortion was always more audible than compromising on drivers to bridge that midrange region. Whether that is appropriate for bass speakers is of course a different issue. Most commercial designs for hi-fi or PA are two way designs avoiding the problems of complex crossovers and can sound really quite good. My favourite sound for bass so far is going through the PA speakers, mine have fairly long throw Beyma 12" drivers and a compression unit with a 1.75" diaphragm going through a 1" exit and crossing over at 1.6kHz, I've bought some 6" drivers that claim to go up to 10kHz and at some stage i want to experiment with them both as conventional mid-range drivers and covering almost the full range (say 150Hz up) with a sub covering the bottom two octaves. For me the big question is what does really matter when playing live? In most situations i end up rolling off the bass because real rooms end up reinforcing the bass more than is comfortable. If the dispersion at 3kHz is restricted to 45 degrees is that OK? It might even be ideal, the width of the stage at the front row of the audience. Do i need 180 degree dispersal across the frequency range? Can you actually detect 10% distortion at 40Hz in a live band situation? How about 20%? What does that mean about Xmax calculations? All this tells us where to set the compromises of course.

Glad it's been cleared up that it is the Pro, looks like the cheapest solution is to buy a second hand cab. This is the replacement [url="http://www.bluearan.com/index.php?id=EMIDELPRO15A&browsemode=manufacturer"]http://www.bluearan.com/index.php?id=EMIDELPRO15A&browsemode=manufacturer[/url] You could probably get away with something like the Fane 15-500 which is a bit cheaper because it has a punched chassis but is still £80+. If you replace it with something cheaper like the Eminence Beta then you will have to re tune and accept a big change in the tone. Even this will cost you £50-60. If it is a Delta Pro (and I've no reason to doubt that it is) then there should be no trouble getting it re-coned, though that wont be cheap either ring Watford or Blue Aran for a quote then decide

Oh, Bill is spot on about all the mystic mumbo jumbo on the Big E website. I expect they also use the vibrational power of crystals to reach into the fifth dimension.

I've got a couple of six inchers that claim to go quite high, I've two schemes planned for them, to try them in a critically damped sealed cab and to experiment with different crossover frequencies and to try building a mid-horn cab to sit on top of my normal cabs. I'll let you know as soon as I make a start or you can contact me in the new year and prod me into action if you wnat to get oin with it sooner.

I'm pleased it has turned out this way for you, The bass sounds pretty much as I predicted so that is reassuring. The speaker has a pretty well controlled top end and most of the commercially available drivers have a characteristic peak in the 2-4 kHz range which gives them their character. The aluminium Hartke will be particularly characterful which is why the shape control works so well on it, basically it allows you to filter out bits of the peak. I have a hartke 3500 top on which I use the graphic to dial in the more typical bass cab sound when i want it. I'm currently using my Beymas in PA tops and can let you have details of the horns I use, which will give you more extended cleaner tops at the cost of doubling the expense of your cab. I'm also working on a 6" driver based cab to punch out a few more mids which I can share as soon as i get round to it. 10" drivers are too big to be good mid range drivers really.

[quote name='stevie' timestamp='1387213455' post='2309478'] Phil, I appreciate that you can put a more complex spin on it, but let’s not compare apples and oranges. Yes, you can make an expensive 15 that will have better midrange than a cheap 10 and you can even make a 10 that has no midrange at all. But it is still the case that (ceteris paribus) large cones are simply not as good at reproducing higher frequencies as smaller cones, and that the larger the cone the lower it tends to break up. By the same token, when a lot of air has to be moved you need a large cone area. It’s the balancing act that makes speaker design so interesting, don’t you think? [/quote] Hi Stevie, You're right, there's a bit of me that watches from afar and says 'you can't still be interested in all this can you?' but it is that combination of science and craft that I just can't leave alone, plus the sheer joy of making very loud music! It'll be a sad day for me if they come up with a perfect replacement for the moving coil loudspeaker. There were a couple of things behind my post. Mainly I don't think most of the people reading here will realise how much of the sound we hear is due to the cone flexing. I've never seen a discussion of it on BC. Most people I suspect think of the cone moving backwards and forwards as a stiff piston and think the sound is coming from the whole cone. You'll know it isn't but others won't and it has relevance for bass drivers in particular. IMO it is this that gives speakers their 'sound' more than their bass response in the bottom two octaves. Because of the way we work with Thiele/Small equations and the programs like WinISD that run them we tend to concentrate on this a lot, but our ears are so much more sensitive to what is going on in the 1-5kHz (midrange) and we tend collectively to gloss over that a bit. A couple of years ago I built a 4x10 as a kind of test bed for developing a bass cab, I used two different drivers in it, the Fane soveriegn 10-125 and 10-275.The first with a light cone and a smaller magnet and the second a heavier cone, larger magnet and stiffer suspension. the second one has a cleaner and slightly more extended bass response but only really extended up to 3000hz. This clearly wasn't enough without a midrange driver and they are currently doing duty in a pair of stage monitors crossing over to horns at 2k The thinner more flexible cones in the cheaper 10-125's give an output up to about 4500Hz and sound much better as bass speakers, I still use them in a 2x10. This is my real bugbear coming from designing hi-fi speakers, I'm not convinced there's a lot of design going into commercially available drive units, There's a lot of over damped, low excursion drivers where they seem to have just stuck a bigger magnet on a cheaper design without considering the use for which the driver is intended, Just a marketing opportunity with no need to re-tool. Speakers recommended as bass drivers which are just unsuitable due to under damping, huge Vas values and low excursion and of course little control over the cone's behaviour under break up, with some Eminence units having 9dB peaks with very sharp peaks and troughs in the frequency response showing little damping of cone resonance. It seems as if Alex Claber is having some input into the design of his drive units, that's a luxury I'd love to have.

[quote name='stevie' timestamp='1387116529' post='2308304'] The other factor that I've never seen anyone mention is that smaller cones have a superior midrange performance to larger cones - given an equivalent technology level, of course. So at mid frequencies (say 500Hz up) a 10 will always have lower distortion, fewer delayed resonances and a higher natural breakup frequency than an equivalent 12 or 15. I think this is probably why many bass players like 10s. [/quote] Hi Stevie, to be fair it is a little more complex than this and a bit more tricky for designers. A 10" speaker will only normally operate as a rigid piston up to 1200Hz above this the beaming starts and the weight of the cone becomes harder to accelerate and decelerate causing all the problems you mention. To deal with this most if not all bass speakers operate with some (hopefully controlled) flexing of the cones. If you wanted to cover from 500 up to say 5000Hz you'd need a tiny 6cm driver like the dome mid-ranges in hi fi speakers. To get the 500Hz energy involved in bass applications you'd have to have a driver this size horn loaded.. All the things you say are true of a lighter cone but once the cone starts flexing it depends upon where it flexes, and it is possible to design a 15 with the right flexure and cone damping to reproduce better mids than a 10 that has a beefed up, thicker and heavier cone designed to go down to 40Hz. This flexure means also that the radiation or dispersal pattern for large drivers isn't always as poor as stated, A 15 may be radiating most of the mids using the central few cm of the cone. For me it seems that if you want lots of deep bass you are better off with a large diameter cone, if you want good undistorted mids and good dispersion then smaller lighter cones are a better starting point but you can make a small cone go deep and get good highs out of a big cone by making compromises in their design. Nearly all of these compromises have been tried by somebody at some time.

[quote name='xgsjx' timestamp='1387069801' post='2308013'] I think you may have misunderstood what I was saying, though I could have worded it a little better. But maybe a good thing as you then went on to explain quite a few things. What I meant was that a driver's diameter doesn't mean it has a particular sound. It's down to lots of factors. The 2 15" Marshalls that I had in the 80s had nowhere near as much bass as the 2x10" Makbass that I use nowadays. Though this is most likely a mix of better designed drivers and better designed cabs. [/quote]That's all fair, I hope you didn't think it was a personal thing I'm an ex science teacher and I can't resist my instinct against the unqualified statement. My wife is an English teacher and can't resist correcting my grammar. Hope it opened up the debate though.