Phil Starr

Just on the physics of the thing heat and temperature aren't the same thing. A bigger amplifier will produce more heat but will be designed to radiate it through a better heat sink so the temperature rise should be the same, it is temperature rise that challenges your components. Any decent amp should handle full power forever, so unless you set it up on an Aussie tennis court they shouldn't blow. If is did overheat the protection circuitry should cut in and limit the power. It won't matter to the heat sink what frequency is using the power and the only problem with lows this deep is that we can't hear them and start boosting the bass, meaning we go right up to the limits. As you normally cut the bass a little this shouldn't be a problem. There's a slight comment about your eq and what you are trying to achieve. If what you want is just a hint of clean lows a thumpinator or other filter works better than a tone control. A lot of these filters work at 24db/octave, most graphics are a lot more gentle than that. Knocking everything below 30Hz will mean your speaker coil stays within the magnet gap which will improve the sound at all frequencies as well as improving its reliability so a sharp filter with your tone control back to neutral may give you more deep bass and a better sound all round. in the end though it is difficult to produce these frequencies without setting off all sorts of room resonances.

Thanks guys, I think you are confirming mainly what I feared, that we are the only ones that really care. I think I prefer playing the Jazz and it sat nicely below the mix in my old pop band, I even used flats then. With the new band the P-bass which is active and has a bridge pup can do most of the tones I need and sits well with the band. looks like I'm a P basser after all.

OK I'm a lucky guy with the luxury of choice. I have two 'good' basses that I'm really comfortable with. A Highway 1 Jazz and an American Deluxe Precision. I had no intention of being a Fender man, if you'd asked me three years ago I'd have said you get better quality £ for £ almost anywhere else, but these two came up cheap, I couldn't resist and they both play and sound great. I'm happy with the basses but my question is what to do live? There's little doubt in my mind that the P-bass sits better in the mix for most of our songs (Indie covers mainly) For a few songs the depth of the Jazz works better. At home the Jazz sounds so much better, to my taste anyway. I take both to gigs, just in case. I take spares of everything critical, even PA speakers. So, should I start swapping basses? I hate it when the guitards swap instruments, particularly when one puts down the acoustic to pick up an electric whilst the the other swaps to pick up their acoustic. How important is having the right tone compared with continuity?

This is the other main supplier http://www.bluearan.com/

[quote name='largo' timestamp='1389622159' post='2336178'] I think a standard "rectangle" box with an upward angled baffle & speaker behind the grill is a great idea and wouldn't affect cab depth too much. It only needs to point upwards maybe 10-20 degrees, not 45 or anything. And a bug bear of mine, a cab that's wide enough to sit flush with a standard 19" rack-mounted amp. That's all, cheers. [/quote] Funnily enough we were discussing the need to match the 19" amps this morning. It's an ideal and it does make stacking cabs easier but tricky to achieve with smaller cabs. If we can we'll do it but how much should we compromise the sound?

[quote name='Beer of the Bass' timestamp='1389620690' post='2336159'] Would that be using the Faital 8" drivers that a couple of the US builders are using? I think my interest was piqued when I saw that the displacement should allow them to get as loud as many 10"s. Given that a 1x10" does me for a lot of my playing, and I use buses a lot, this could be very much of interest to me. [/quote] We're talking about a number of drivers for all the designs, There's the Fane 8-225 and Precision Devices do a lovely 8 with great extension at the sacrifice of sensitivity. the trick is going to be to home in on th best drivers in their class

[quote name='charic' timestamp='1389610388' post='2335992'] How about a home practice cab? Takes the full wattage of a gigging amp (mines 1kW) but is small and doesn't risk damage (dummy load or something may be the easiest way I guess?) [/quote]We're quite keen on a home practice cab, something small and unobtrusive but with a satisfying sound at the sort of levels you will practice at. There is a technical problem with something small built to handle 1000W though. Heat dissipation. Small speakers have small coils and less metalwork so don't handle such high power before burning out. The simplest thing would be to turn down of course, 50W into a decent speaker is going to annoy the neighbours quite enough anyway. It would be possible to wire a 4x6 for example so it ran at 32ohms and your amp would only drive 125W into that or a 16ohm 2x8 could be made to handle 200W easily enough. It's more likely we will come up with a 1x8 design for this purpose, but it won't handle quite that much!

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.