Phil Starr

Big apology to all those following this, I've joined a new band and have new set list to learn and bass playing is what it is all about. My aim was to summarise about a weeks worth of discussion per post but I'll have to condense that a little to catch up. When I left it we were starting to look for a good driver (the actual speaker) for our cab. I won't pretend it was an unbiased search. Stevie was keen we look outside the usual suspect (Eminence) I had previously done the search and bought a couple of Beymas. Celestion and Faital were mentioned early on. Technically we had some design specs to meet. We decided it was practical to make a single 12 capable of matching a drummer which meant achieving 120dB @ 1m within its maximum power. Most 12" speakers handle around 300W so that means something like 95dB/W efficiency. We also decided a practical 1x12" needed to be pretty portable so a speaker capable of working in a box no bigger than around the 60l mark was needed. We also had a bias for something which would handle low frequencies without overloading too easily, this means looking at the excursion or Xmax and anything with an excursion below 4mm was out. Then we considered frequency response. We discussed the bass characteristics a little. The choice is really between an under damped speaker which characteristically gives a bass peak at around 100-120Hz of a few dB and rolls off quickly below that or a well damped speaker with a bigger magnet and more control which would give a smoother response and a respectable output down to 40Hz ish. We didn't consider an over damped speaker which roll off gently from above 100Hz but can give good tight bass and acceptable responses if you apply a little eq. Damping is measured in the Q of a speaker and overall Q or Qts needs to be about 0.4, anything above 0.5 is underdamped and likely to give a bass hump in a practical cab anything below 0.3 is likely to be very tight and lack bass output. We decided to go for a modern controlled bass response so we looked for speakers with a Q between 0.3 and 0.5. if we wanted to look for an 'old school' sound we would have looked for something with a Q somewhat higher 0.5-0.6. It's too easy to get a bit anal about bass response. It's the only bit you can really control as a cab designer and we are all bass players, but most of what we hear from a bass is actually mids and the higher frequencies are much more important in defining the 'sound' of a cab. We wanted a single speaker to cover the whole range for our first cab it would need to go up to at least 3500Hz and preferably higher. 12" speakers naturally cut off at about 1100Hz and response above this is down to the cone flexing so the sound comes mainly from the middle of the cone. A lot of speakers actually give a big increase in output at breakup so you get a peak in output from 1-3000Hz another contributor to the 'old school' sound. More about this later, probably. So the 'ideal' driver would specify Fs 40Hz Qts 0.3-0.5 Xmax >4mm 96dB/W frequency response 40-4000Hz +/- 6dB We modelled all of these and probably some more Beyma SM212, Celestion BL12-200x and BN300X, Faital PR300,Fane Soveriegn 12-300, Eminence Deltalite 2512, 3012HO, 3012LF, Beta12-II. more soon, I have to practice

The Monacor is designed to crossover at 5kHz so you couldn't use it with the 3012lf unless you wanted a hole in the response. I'm not a puritan about thin walled cabs by the way, I can see advantages with a rigid cab but the weight advantage isn't all it's cracked up to be. Alex Claber has stated that weight saving isn't his main reason for building cabs that way. What I'm sceptical about is that the difference between a well made lightly braced conventional cab and an equally well made thinner walled and heavily braced cab is that apparent in a gig situation. Since the weight saving is minimal and the complexity of build greatly increased I question how far it is worth it. A reasonably well braced 12mm cab might be worth thinking about too. One day I'l get round to building two cabs and do some A/B testing. Incidentally I have a 15" Deltalite in a 3/4" cab and the total weight is only 18kg, your cab will be smaller and lighter. Having modeled the 3012HO as part of our design process I think it would make a great cab on its own, though a single one in a West Country pub might well let the higher frequencies bypass you, two together would probably be OK. The sound is going to be very different from the Jacks even though you are using the same speakers, because of their design the Jacks have a 10dB difference in levels between the horn output at 300Hz and the reflex output at 100Hz and this colours the sound. the reflexes won't be as loud but the bass is going to be the same as the mids so the balance will sound deeper subjectively. One thing occurs to me, you really aren't too far away. We are looking for a 3012 to trial as part of our design, if you came up to Somerset for the day anytime it would be simple enough to clamp one of your speakers into a cab and for you to try it, if the sound is one you like the dicision is made. Ideally we'd like to run some tests at the time but this could be fairly flexible. I've got a couple of 50l cabs here.

If something looks too good to be true it usually is. Having said that the magnet is a decent size and the Chinese are banging out so many speakers for other people that it wouldn't be surprising if something half decent didn't find it's way here. there are three potential shortcomings, the first is that the speakers don't meet their specs. The power handling is probably right given modern glues and a 2.5" coil. Sensitivity is quite high for a cheapie but could be possible with a 50oz magnet. What you can't get is an average magnet high sensitivity and lots of deep bass. Have a look at the Eminence delta [url="http://www.eminence.com/pdf/Delta_12A.pdf"]http://www.eminence....f/Delta_12A.pdf[/url] with a similar magnet and coil and you'll see that the sensitivity is similar but the resonant frequency is much higher at 55Hz. To get this sensitivity at this frequency I suspect the excursion has been reduced and this speaker will overload or compress at relatively modest levels. If you are lucky it will sound OK at low levels but overload at noisy rehearsals depending upon what sort of music you play. Depends upon price really, you can get an Eminence beta12A II for about £50 which would probably be at least as good and has all the parameters available or you could pick up a used cab for under £100, but this might be a cheap way of dipping your toes into self building. It probably will beat your car sub hands down.

Hi Rich, there's a lot of questions there I'll try and deal with the woodworking ones first. If you do go for a 50-60l cab then it is quite small and you don't have much flexibility with shape. For example with a 30cm driver and a 10cm horn plus enough wood left to be strong enough to fix to you have a 50cm high cab and you want it 40cm wide. this means that for a 60l cab it will only be 30cm deep. This compromises the port as it can only really be 20cm long or it gets too close to the rear panel. If you want to tune deep then you need to restrict the port width or bend the port which introduces more problems. If you use a narrow port it doesn't need to be so long but can suffer wind noises at high levels. If you use a deeper cab you end up with a square front and an almost cubical cab where all the panels resonate at the same frequency. In practice you will come back to the 30x40x50 shape or thereabouts. Now the horn/tweeter. Firstly there are no decent piezo tweeters in reality, I've tried quite a range over the years and they do a job but with limited success. The old Motorola's which most of the currently available ones base their designs on were as good as anything the current Chinese mass produced ones are fairly poor and production in Europe and the States has ceased as far as I know. They'll colour in a bit of high end fizz and that's it really. 9mm ply really is very flimsy for making a high powered cabinet, The only way to stop it resonating and transmitting sound is to use extensive bracing. The bracing could easily end up weighing the same as the rest of the cabinet and adds a lot to the complexity of building the cab. I know it is very trendy in these pages to go for rigid, lightweight designs but it takes a lot of development to get it right, it may make sense for commercial builders with CNC routers and design budgets but don't knock the intrinsic properties of 3/4" ply. Secondly, why do you want a horn? Most of the stuff you want to hear from a bass ends at 4-5000Hz. A lot of horns don't cut in until this level, so are irrelevant to the sound, all they'll add in is string noise. If you want a real 'hi fi' accurate sound then you want something that covers the 1-5kHz range. Something like a PA horn. I sometimes use my PA speakers for bass and it does sound nice, The horns in these crossover at 1.6kHz. If I wanted a cleaner bass sound designed in I'd probably go for a 6" driver or smaller to provide the 1-5kHz range. If I was designing with a wide frequency horn or a mid range driver like this in mind I probably would go for a 'proper' LF driver but the 3012HO is a capable driver and as you have them I'd definitely try them first.

Hi, how soon do you intend building this? We are working on a design for a 50l cab which will match this driver, slightly derailed because I joined a new band and have 25 new songs to learn. This will be a free design for anyone to copy. The 3012HO is an excellent driver. http://basschat.co.uk/topic/227904-1x12-cab-design-diary/ You might find this interesting too http://basschat.co.uk/topic/200152-1x12-diy-cab-build/ If you go onto the eminence site you will see that the large cab has worse power handling than the more compact cab and they recommend using it with reduced power. This is a feature of all reflex designs not of this particular speaker. I really wouldn't go any bigger than about 70l nd we ended up going for 50l as a good compromise.

You don't need to worry about class D, just like the 'old' amps there are some that are oversold with 'car stereo watts' but there is no inherent reason why they shouldn't meet the specs or deliver every advantage they promise. Most of the weight saving is in the power supply which works the same way as the one in the computer you are reading this on, and they work. I'd always say there is no need to be louder than the drummer. if they need to mic up the drummer you can DI into the same PA the drums are going through. Money no object and I'd go for the AER Amp One, it's not stunningly light for its size but it is tiny and it delivers unbelievable sound. It looks like a practice amp but it'll more than match the beefiest percussionist. I'd say it's one you need to try if you can afford that much, if it is for you then you know you have the best solution on the market. If that style isn't for you then go for some of the options above and doubtless yet to come, Has anyone said Barefaced yet? The other option for someone who likes clean is to go for a powered stage monitor or PA speaker. The best ones can handle bass no problem and will be designed for a flat sound from the off. Just a thought.

I'm afraid that in oversimplifying some of the advice is a bit misleading. I'll summarise but you can get more detail here http://www.ultimate-guitar.com/columns/gear_maintenance/making_it_loud.html Most of the power from your amp is wasted as heat, only about 5% ends up as sound. The amount wasted varies from speaker to speaker. this is reflected in the efficiency of the speaker usually given as how loud it is for just one Watt or dB/W Some bass speakers give just 92dB/W and the best in terms of efficiency maybe 102dB. Every time you increase the power by 10 you get an extra 10dB and you need about 120dB to match a drummer. That's about 70W through the loudest speaker and 700W through the quietest. As said 300W through an average speaker will be enough. Size matters but only a bit. A big speaker will be louder than a small speaker if everything else is the same and doubling speakers up gives the same advantage in sound levels as having a big speaker, it's the cone area that counts. However lots of other things like how powerful the speaker magnet is will count too. It's possible for a 12" speaker to be loud enough on its own if it is capable of moving far enough and has a powerful magnet and many 15's will do it on their own too. If you are using a 100W+ amp in a rehearsal the usual reason for not hearing is that you are standing too close to your amp and it is pointing at your ankles not your ears. Tipping it back and pointing it at your ears will help a lot. Hope this helps

I'd like three black ones, the dipped small chamfer would be good, but any will do.

As someone who has spent a lot of time designing and listening to speakers over the years it is quite clear to me that you can detect very small differences between cabs in A/B testing even a tiny resonance at a very narrow frequency range can jump out at you in a listening test. You can easily hear differences in amps in A/B tests and even in speaker cables. Equally it is amazing how your brains can fool you into hearing something that isn't there. This is true of all our senses, I used to be a science teacher and you probably did a little experiment at school with hot, cold and warm water. Put one hand in the hot water for 60secs and the other in the cold, transfer them both to the warm and the 'hot' hand perceives it as cold and the cold hand perceives warmth. The same is true of sound put on a favourite track on your computer and turn the bass down just noticeably; obviously the song sounds bass light. Go on listening for a few minutes and turn the bass back to normal halfway through the song; it will sound bass heavy. Your brain has tone controls! My poor kids have been used more than once for blind testing of my projects because when you've spent hundreds of pounds and weeks of time developing something it is amazing how easily you believe good things of it. As bass players we all know the eq we set up in our homes often sounds terrible when playing with the band and that the sound in the rehearsal room is never like that at venues leading to much frantic knob twiddling. So, whether the minute differences we can detect are significant is a moot point. When shopping for a cab it is well worth spending time listening to speakers with your amp and your bass I would say, but don't expect the holy grail. Get something you like and then relax, the audience aren't really going to worry if you use Aguilar or Peavey unless you have a basschatter there.

Black would be ideal and stick on appeals. preferably as small as the one that started this off. The larger ones that are commonly available hang out beyond the pick guard making mounting them tricky.

If they are going to be around a couple of quid each I'll take 5.

It's good to have something with a battery, you end up with too many leads otherwise. http://www.youtube.com/watch?v=QVCJFE3bW9A this clips into your belt so you can move around whilst playing. I have one and I'd recommend it but the gain is just a touch on the low side, does the job though. My favourite is an old battery powered mixer for dubbing sound onto VHS tapes. You might find something similar if you are lucky.

I think what we are saying is that if they are up to the spec they are quoting then they would potentially be fairly good speakers depending upon how you use them of course. However they are unbelievably cheap and if something looks too good to be true it probably is.

Depends upon the price obviously but I'm happy to buy a few. I need two currently but I'd stock up if they were cheap enough. £8.50 is no problem if that is what it ends up as.

Balcro's car analogy is excellent. If you increase the weight of a car you need bigger springs. That's simple enough but if you just do this it is going to bounce around more, you need to change the shock absorbers to exactly match the increased weight and the stronger new springs to get the best out of your pimped vehicle. Mass, springiness and damping are all things which need to be calculated in speaker design and balanced out. You can't change just one thing you have to look at them together. To get deeper bass you need to tune lower and move the cone further. Just as in your bass thicker heavier strings or cones do lower the tuning, as does slackening off the tension. Just as Balcro says increasing the weight means less cone movement for the same power. Then to get the extra movement you have to have a longer voice coil. This also wastes power because most of the coil is out of the magnet at any given time and using power but not making the cone move. You can put in a bigger magnet to get the efficiency up again but this will also increase the damping and the cost so you have to get that right too. Price for price you trade bass extension for efficiency.

Thanks for this, I'd be very interested in a couple, or the file if you decide not to take this on.

[quote name='LukeFRC' timestamp='1391449422' post='2357292'] I'm going to say... can this thread be pinned please mods? [/quote] thanks. It might be better to create a new thread once the design is finalised with the design at the top, then we can drop further designs into that thread. We can link to this diary from there. Our hope is that enough people will build these and then tell us of anything we might do to improve future designs.

It probably uses some sort of Auxetophone http://www.douglas-self.com/MUSEUM/COMMS/auxetophone/auxetoph.htm#aux invented by Charles Parsons who invented the steam turbine.

Where did you get the thumb rest?

if you want to keep the character of the cab then don't replace the drivers. The character is both in the low end bloom using those speakers in that size of cab and in the various resonances in the high end. Replacing the speakers will change both though we could probably find something to match the low end. The new speakers might sound better or worse to you but will be different. The other thing is that there isn't the same choice of Neo drivers as there are ceramic ones. Because neo is an expensive material the neo drivers are designed to be high quality. Your 4x10 is designed on the basis that 4 low cost drivers can do the job as well as fewer more expensive ones. The cab itself is probably fairly heavy too so you wouldn't have a genuine lightweight cab. If you want lightweight there are plenty of cabs to audition to see if you can get the sound you want and it would probably cost no more to trade up than spending £3-400 on four neo drivers plus the value of your cab.

[quote name='ebenezer' timestamp='1390557034' post='2346686'] i too am looking forward to this!....just for info...I swapped the 12 inch driver in my aguilar gs 112 for a eminence 3012 ho kappalite expecting good results!!.... all i can say is,i was unhappy with the sound(yes i know the stock driver is 4.8 xmax and 95db......3012 6.2 xmax and 100.5 db)...i found it only a small amount louder than stock driver.....sound wise,it did not mesh well with tweeter and crossover...too aggressive in the mids and the bottom end not that good.....3012 now back in the box!....returned cab back to standard and sounds great!.....i think correct cab design plays a large part .it seems the lesser deltalite 2 might have been a better option(looking on talkbass) regards....mark [/quote] Hi Mark, the 3012HO is one we are modelling. It's a good example of what I was saying, Coincidentally the link http://www.eminence.com/pdf/Kappalite_3012HO.pdf is for that driver. If you look at the graph the sensitivity below 500Hz is only 98dB/W and when we modeled it it was slightly below this. The 100.5 they quote includes the mid peak, it's fair enough because they tell you how they test but also misleading. I wouldn't have expected much increase in sensitivity. To get the best out of it you would have had to have modified the crossover which was designed for the stock driver. Ideally we'd like to run tests on the 3012HO driver but we don't have one to hand. If yours is still back in its box then pm me.

To be honest I won't pretend the search for a driver was quite an objective trawl through every available 12” speaker. We’ve all built cabs before and between us had a number of 12” drive units sitting around to try. We had a fair idea of what we were looking for, though if we had turned up a speaker dramatically better we would have used it. For clarity I’m making our search look more systematic than the process probably was It makes designing more interesting though when you know you have to justify your decisions to other people who probably know more than you, and who won’t mind saying what they think! The first thing to do is to trawl through the spec sheets, keeping a sceptical eye open for manufacturers over optimistic claims. There are two things to keep an eye open for; the overall ‘sound’ of a speaker is determined roughly by its frequency response, and the bass performance by the design of the motor cone and suspension. Most speaker manufacturers publish the frequency response as a graph http://www.eminence.com/pdf/Kappalite_3012HO.pdf The thing to look for in the frequency response is the shape of the graph above 1000kHz, which is where our ears are more discriminating in what we hear. Below this the shape also depends as much on the box as the speaker itself and they aren’t all measured in the same box. If you look carefully on the spec sheets there’s usually some small print to tell you how the tests were done. The first thing is to see how high the response goes, if you don’t have a decent output (within 6dB) up to 3000Hz then your bass is going to sound as if the tone control is rolled right off before you start. A lot of 12” drivers are designed to be the bass unit in a PA speaker so they don’t need any top and you can reject all of these for a single speaker design like ours. Ironically if the speaker says bass driver or LF it probably isn’t going to work as a bass guitar speaker. Ideally I’d like an output within 6dB up to at least 4K. You’ll see two types of response. All speakers have a fairly smooth responset up to 500Hz ish which we think of as mids then the response starts to wobble. This is where the cone won’t work any longer as a piston, usually starts to flex and and resonate, and more of the sound comes from the central part of the cone. Depending upon the cone design the response will either bulge upwards by a few dB’s falling off at somewhere over 2K or be fairly even, with a bit of a wobble. The bulge is really useful for adding colour to the sound and most commercial speakers have the upper mid bulge, You have to decide early on whether you want a coloured ‘old school’ sound or something more neutral. To predict bass response I like to look at three parameters in the spec sheets, [b]Fs[/b] is the resonant frequency and tells you how deep the speaker will go. It isn’t an absolute limit but once you put a speaker in a cab it will start to droop in bass output around and probably above this point. The next thing to look at is [b]Xmax[/b] (and Xlim if the manufacturer gives it). Xmax is about how far the cone can move before the voice coil moves out of the magnetic field. This is important because the sound will distort and compress at this point. Be careful because different manufacturers have different ways of specifying Xmax. Some simply measure the magnet and the coil which gives a worse case Xmax, others like Eminence give Xmax under a certain level of distortion which makes them look a bit better but, to be fair, a bit more ‘real world’. Where we could we chose to use the voice coil overhang measurements but they weren’t always available. If Xmax is low (3mm or less) the speaker isn’t likely to handle a lot of deep bass without distorting at high sound levels, so we wouldn’t look at these for bass unless we were designing a multiple driver cab. The next thing we looked at is a weird parameter called [b]Qts[/b]. I won’t try to explain it here but a high Q (above 0.5) means the speaker is poorly damped. It will only give a flat response in a big box, in anything of a practical size it gives a big bass hump arund 100Hz and will sound warm, woolly, and very old-school. A low Q speaker (below 0.3) is going to be well damped. Just like a sports car tracking the road it is going to track the bass well, but the bass output will be tight and fall in output from quite a high point above its resonance. Just right for this bear is around the 0.35-0.4 point. By and large a powerful magnet creates low Q and better damping of cone movement so low Q speakers are more expensive and heavier. The last thing to look at when choosing a speaker is the efficiency, how much sound you get for a watt. This is usually given as dB/W. Look at the graph ideally at the flat bit below 500Hz which gives a better idea of bass efficiency. Most manufacturers give an efficiency which includes the midrange humps and bumps, this makes their speaker look better than others that don’t use this trick. Nearly all the speakers we looked at were around the 95-98dB/W mark and there wasn’t much variation in sound levels once we modelled them. So taking all of this into account we came up with a shortlist of candidates, which had to go up to 3kHz, have a Qts between 0.3 and 0.5, an Fs of less than 55Hz and an Xmax of at least 4mm. All the speakers we looked at had an efficiency above 94dB/W. I’ll run through the choices we modeled next time.

Hi, this is a 'diary' of how we are designing our 1x12. It is a bit behind the actual discussions we are having but I'll catch up as quickly as I can. I’ve posted this in response to our earlier thread. Three of us at Basschat (Stevie, LawrenceH and myself) have decided to publish a series of open source cab designs and people asked us to describe how we created the design so they could follow our reasoning. This is going to be the design diary for the 1x12. The first decision was which cab would be first. I initially suggested 1x15, a 1x12 and a 2x10 as initial projects. Stevie and Lawrence were both planning an 8” cab so that will be added in as an early design and there was some discussion about 2way designs. In the end the decision to go for a 1x12 was an easy one. We’ve got a range of 12” drivers around and a single driver in a straightforward box makes an accessible start to home building. We should be able to come up with a design that will keep up with a drum kit on its own and be enough for small-medium gigs. Adding a second cab or building it into a 2x12 would cover most people’s needs. Initially we didn’t have a design spec, but what has arisen through our discussions are these: Capable of keeping up with an unamplified drum kit (120dB across most of the frequency range) Compact (60l or less) Neutral /clean sounding Easy to handle Good low frequency power handling Readily available components, and easy to build Value for money We didn’t specify power handling. The critical thing is not how big an amp you have to use but the actual volume of sound you can expect the speaker to produce before it farts out. If it is loud enough with just 50W then this would be a positive, if it handled 1000W then it would probably be loud enough but fail the value for money test. As it happens nearly all 12's handle about 300W and have similar sensitivity of about 95dB/W. Easy to handle ties in with weight, but also size and proportion. You need to be able to lift your cab, but it also needs to fit through doors, including car doors, and not drag along the ground. We decided that 60l was the biggest our 1x12 should be and this would intrinsically make the weight and size manageable. Good low frequency power handling is a difficult thing to define. Almost no commercial 12” design will go down to low B at -3db or better and be capable of that at 120dB and ours won’t either. ( I don’t know of any commercial bass speaker that will but someone else will) What we are looking for is something that won’t shake itself to bits at high power and reproduces low E cleanly and at a decent level. We also want to see something that can handle a decent proportion of its rated power without distorting . More about this later. UPDATE A lot of information has been lost in the last couple of years with changes to both this site and Photobucket which I put my old pics on. If you want to build these cabs I've retrieved the dimensions below. I need to go back and see if I can come up with something better when I get time but it ought to be possible to build one of these cabs from just the dimensions. If you want to do a build PM me and I'll fill in any details Members 60 2,401 posts Location: Chard,Somerset Report post Posted July 8, 2015 If anyone wants to start a build before I've had time to write this up and get drawings done it shouldn't be too difficult. The cab is constructed out of 12mm ply and fitted with a Beyma SM212 driver available from Blue Aran and others.The external dimensions are 360x424x530mm the baffle front is set back 30mm from the front of the cab so internally the depth is 306mm. The four ports are made of standard guttering downpipe 190mm for a 50Hz tuning, and 260mm for a 40hz tuning. All this information is elsewhere in the thread but it's probably hard to find. I'll cut and paste the important bits later but everything is there below including some frequency plots measured from the prototypes.

OK, update time. We have decided to go for a 1x12 as a first project, a 50l cab, 300W@8ohms, should be capable of producing 120dB@1m across most of its frequency range and hence capable of keeping up with an unmic'ed drum kit. It should be a comfortable one handed carry for most of you. The current design is going to be fairly neutral sounding and should have good control of the lowest frequencies. The design has reached the stage of moving to build a prototype and we have a list of drivers to audition. We are currently looking at the port design and there is some debate about the significance of wind noise (chuffing) in the ports versus the ease of build and overall size and shape. We will resolve this by tests on the prototype as well as deciding on the final choice of driver by auditioning a number of drivers. At the moment we think it should be possible to build a high quality 1x12 for around £150. I'm going to start another thread to talk anyone who is interested through the design process, once I catch up it will develop as we do.

[quote name='skidder652003' timestamp='1390071487' post='2341206'] you've heard the old tosh we churn out Phil, you only need one bass for rock mate, guitards now using a Les Paul as well as the strat and it drives me nuts with the swap overs, we've told him to do it as little as possible and let us (me and drummer) start some intros while he does, but what with his reluctance for a set list ( a whole other thread!) its all becoming a real issue with the tumbleweed blowing between numbers ( I have no stage front craft) [/quote]We all love our guitarists, don't we. I don't play anything that needs a dropped tuning or 5 strings and you are right about breaks between songs. It's going to be one bass for me then with the spare being just a spare, although I've never had a failure.