Phil Starr

Hi Luke, I've been on holiday and then my computer crashed terminally so I've been off the boil Just to recap and bring everyone up to date I've built two prototypes out of 12mm lightweight ply and have been using them at practice. I've now installed some bracing which has tamed the rather alarming resonances of the panels and tightened up the sound. I quite like the way they sound now. I've agreed with my co conspirators to do some testing before we release a final design. Three issues need to be resolved, the cab tuning, the port area and the wall material. The current cabs are built with four pipe ports that can be blocked off and altered in length to achieve different tuning. basically I proposed a 40Hz tuning which gives us lower excursion at extreme bass and keeps it within the speakers damage limit up to 300W others have been suggesting a 50Hz tuning which gives a touch more bass and power handling above the extremes. we need to see if there is an audible difference and if it makes any difference in actual use. the port area issue is about balancing the avoidance of wind noise against ease of construction. Big ports are quieter but can pose construction problems or we could buy expensive(ish) flared ports. If we can use something small and simple we will, but the best way of seeing how far we can push it is to try out different set ups. At some stage i want to open up the chance to try the speakers to basschatters to feed into the design

Interesting, that looks like a fairly significant crossover. Did you consider using something simpler like the 'bright box' approach with just a simple 6db/octave high pass filter to the midrange and no filtering on the bass driver? Obviously that would lead to some comb filtering effects and it would be almost impossible to get a flat response but it would be a lot cheaper and simpler and you would get the extra frequencies and dispersion from your midrange driver. How did you decide on the crossover frequency? I assume there are a few octaves of overlap.

Yep half the volume is right. the shape matters in that it affects the resonances in the cab, avoid haveing any two measurements being similar and a cube is the worst possible shape for a cab. However cabs are a compromise and with small cabs there is a real problem in squeezing in a 10" dia speaker into a few litres and making an easy to carry shape, so few practical cabs are the 'right' shape and you may have to put up with a few resonances.

I haven't modelled these but they look a bargain at the moment http://www.bluearan.com/index.php?id=PAUE15350N&browsemode=category

I think that's a great question. Cab design has concentrated on all the stuff below 200Hz because that's the bit the mathematical models and design software address. The bit the box designers control. Then I go in to gigs and roll off the lower frequencies to get the best sound for the band. It's obviously better to have a perfect sound and then shape the lower end but the expensive and bulky bit of amplifying bass is the bottom octave which we can barely hear. If you've not done this before it is worth listening to 41 and 31 Hz http://plasticity.szynalski.com/tone-generator.htm if you start at 1000Hz and scan down the sound disappears, you can't really hear low B fundamental in any practical sense, so why do we make such a fuss? To make it a fair test use headphones, your computer speakers won't go that low in all probability.

Two very simple things: It doesn't matter where the controls are pointed, it's the sound coming out that matters. Read Alex's article on gain at the top of this forum. You haven't buggered your amp. What has probably happened is that it got hot. You did two things, cutting the mids made it sound quieter because we hear mids well and bass poorly (damn those guitards). Boosting the volume to compensate and then boosting bass demanded extra power. Your amp can do this for a while (half an hour apparently) and then it starts to overheat, all your resistances rise with temp and protection circuits activate and the available power falls. the amp is protected but sounds s**t. You turn it off, it cools down and you are back to normal probably. I have no idea if the speaker will take this, it just depends. If you want certain tones the cost is extra power and usually more or bigger speakers, or perhaps a bit of both.

You'd want one of these if you had the space http://blog.sciencemuseum.org.uk/insight/2014/04/24/in-search-of-perfect-sound-introducing-britains-largest-horn-loudspeaker/

Volt make some well regarded hi-fi drivers, the price has always deterred me from looking at them. the one you link to is not really suitable as a bass speaker, it is an overdamped (Q 0.27) driver specifically designed to go into a satellite system for a PA. It rolls off in frequency above 80Hz so is designed to work with a subwoofer. Oh and the Xmax is 4mm the higher figure is the maximum excursion before it destroys itself sometimes called Xlim Your Beymas go further before distorting.

Glad it has worked out for you. The other big difference will be in the excursion, those Beymas will handle deep, loud bass much better, unless you crank them you won't notice it so much but it's nice to know it's there. It'd be really nice to know what you think of the sound after living with them for a few weeks, we all inevitably tweak things until we get the sound we like and that takes time.

[quote name='Happy Jack' timestamp='1400065122' post='2450323'] I'm guessing that was supposed to be "omnidirectional"? [/quote]oops

If your drummer is happy to give it a try then he's a keeper. just like a guitarist who is flexible. My experience is that it is a very mixed blessing. Cutting down the stage volume cures all sorts of issues about balance and feedback. Having a single lead for the drums and a fully mixed sound to the audience is fantastic, suddenly we were consistently being complimented for our sound. Set up and knock down times tumble too.It's also great to have space in the smaller venues. The downside, as has been hinted, is monitoring. Drums are unidirectional and no-one is ever struggling to pick up the rhythm or the cues. All speakers are directional and if you aren't in the path of a monitor you can't hear the drums. We did one gig on a bigger stage and this became a real issue. You've got to plan how each band member is going to hear the drums. we'd done two gigs without problems when this one bit us in the bum. Believe me it's hard to keep the band tight when the bassist can't hear the drums. the other down-side is that the kits have at least a hundred sounds, Only one or two are any good, you really want a kit to sound like akit not special effects from the latest sci-fi film. Don't let drummists have knobs to twiddle.

You can get crimp fitting spade connecters which branch so you can connect another spade. http://www.ebay.co.uk/itm/like/400629036438?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0&ff12=67&ff13=80&ff14=108 http://www.maplin.co.uk/p/maplin-spade-terminal-piggy-back-connecters-red-l26ay try an autospares shop.

[quote name='JTUK' timestamp='1399723878' post='2447017'] What peaked my interest was trying out an HK Elements system and whilst it ultimately failed from our POV as it wasn't versatile enough for the gigs we do, it was interesting in that the subs were very easily to carry and the seperation was enough on small gigs. Larger, you have to double up on the subs and carry 4... and if you carried 4, size-wise, you might just as well carry 2 conentional ones. We quite fancy very pokey hi quality tops...like Martin f10, or Nexo PS10's and we then feel we could get away with 1 sub most of the time... maybe an LS500...and add the second for bigger gigs. The 2xPS10 plus LS500 would do a pub very well, I think. Anyway, with that thinking, I would be interested in passive subs with performance in a compact and light shell. By that I mean 60/70lbs max in weight....pref lighter. Basically that P.A needs to carried in a decent hatchback.. [/quote] OK that is beyond the scope of this thread, which is about bass speakers but I'm sure several of us would be happy to offer help if you wanted to build this and share your experience, if you want to go ahead then start another thread and we will chip in with ideas. A budget would be good.

[quote name='redstriper' timestamp='1399676332' post='2446700'] I have two 15" Flite cabs which I love, they are very lightweight and they sound great, but I believe they are all wrong from a technical standpoint. I play reggae and I like a very deep tone, with no upper mid or treble. I've been told the cabs are too small for the drivers (Eminence Kappalite 3015LF) and the port is too small. They sound great to me but I borrowed an ACME 12" cab and it went much lower than mine do and I wonder if I could get more deep bass extension and possibly more volume level by adding a larger port(s) in a similar way to this post: [url="http://basschat.co.uk/topic/235679-can-i-improve-my-cab-at-all/"]http://basschat.co.u...-my-cab-at-all/[/url] The main problem is, these cabs are made of a composite comprising a foam sandwich between 2 very thin pieces of ply. This makes for a very lightweight cab, but I'm not sure how it will take to being cut with a jig saw. In fact, thinking about it makes me shudder - I don't want to ruin these great cabs. Any advice would be much appreciated. Steve. [attachment=162359:Flite cab.jpg] [attachment=162360:Flite2_amp.jpg] [/quote] The reason Stevie suggested an extra port in the other thread is that by swapping the speakers for ones that move a lot more air you risk chuffing noises from a fairly small port. The port area was doubled to let the cab 'breathe' and the ports lengthened to keep the tuning the same. The frequency response then stays the same. You aren't swapping drive units so it isn't relevant to you. Most commercial cabs are sized for practical purposes and are smaller than the optimum size for the deepest bass. It actually improves power handling in most cases. Too big a cab could be a problem but you aren't changing the cab size. Leave the cabs alone. If the sound you want is the 3015LF in a bigger cab then your cabs are worth more than the speaker, so sell them and buy a couple of drivers. You could build a wooden cab of the 4cu ft size Bill mentions and put your speakers in to try if you are really keen to try that sound, or buy a sub.

Just covered a cab today. Use ordinary PVA woodwork glue, the flat bits are easy, to stick round the tricky bits use a hair dryer to soften the Tolex slightly and it won't try to uncurl so much.

[quote name='JTUK' timestamp='1399633092' post='2446059'] Wouldn't mind a punchy lightweight 12 or 15 sub... [/quote] My original idea was to pump out some simple designs that people could build themselves. Stevie and Lawrence have persuaded me that we need to build and test our designs extensively before publishing them. If you want a sub, or anyone wants a specific design and is prepared to share their build with other people them i'm sure we could give dimensions easily enough. For example building this speaker into a box twice the size (110l) and with a 4.6cm long 10.2cm dia port would give you a sub which would deliver 120db dropping to 116 db at 40Hz. That took me 5 mins to calculate and you could build a cab with that information. I'm sure there are plenty of people here who would help you, or anyone else design a cab, it just wouldn't be one we had built and tested. If not we should be able to come up with 2-3 tested and developed designs a year.

I'm fairly sceptical about wadding. First of all, to answer the earlier question it doesn't alter the effective volume. There's a lot of air in the wadding and it moves inside the cab. I've seen the argument that lots of wadding increases the effective volume of sealed and transmission line cabs and seen some measuremnts that would seem to support this. However the data I've seen implies that only high density wadding has a significant effect on damping inside the cab. Vance Dickason talks about 50% of the cab being stuffed with 4lbsfibreglass/cu ft. The wadding you have is almost certainly too light to be very effective. I've also seen arguments that wadding inside a ported cab is generally a bad idea, certainly it needs to be kept away from the ports, I've tried packing a cab and completely removing the wadding from its pair, ending up with little difference in sound between them. the exception to this is the wadding directly behind the speaker which aims to stop sound bouncing off the rear panel being reflected straight back through the thin paper cone. I like to put some fairly heavy wadding on the back panel and leave the rest of the cab unfilled. This does make an audible difference and I'd move your wadding to the back panel immediately behind the speakers.

I suspect it is 100mm outside diameter if so this is esily available though not so easy in black. Wickes/Screwfix all do it in white http://www.screwfix.com/p/round-pipe-350-x-100mm/15872?kpid=15872&cm_mmc=Google-_-Product%20Listing%20Ads-_-Sales%20Tracking-_-sales%20tracking%20url&gclid=CODQz6OvnL4CFbDJtAodpgcABg

You don't need maths to understand what is going on with speaker sizes until you start to design the cabs yourself. So, in Alex's absence... Thicker bass strings go lower not because they are thick but because they have more mass. The note they make doesn't depend just upon their mass but upon how they are tuned and how flexible they are. It's the same with speaker cones. Heavy cones go lower so a thick 10" and a thin 15 could weigh the same and resonate at the same frequency. Tuning speaker cones depends upon the suspension, the magnetic circuit and the cabinet design, with the rider that you mainly can't get them to do much below their resonant frequency in free air. Interestingly thin cones flex and this means thin cones are often better at high frequencies, though this may be distorted. thin coned 15's may end up with more top end than thick coned 10's. Just depends upon the specific design and where the designer puts the extra paper pulp. The Eminence 3015HO is a good example of this. The other thing is that efficiency depends upon surface area and a lot of cheap large cones can end up making a loud noise, as in the 8x10's around. If you want super small lightweight cabs to do the same they generally need a lot of power. The final consideration is excursion, to make loud bass you need to move a lot of air and small speakers need to move a long way to create say 120dB of 40Hz fundamental. Too far for any single 10, and for most 12's. So, you can get the frequency response from a small speaker but at a cost, one way or another.

I was going to recommend the zoom! I have an Olympus, basically a dictaphone though with fairly good quality. One of our band has the Zoom H4 and it is so much better! The problem is that the standard recorders have automatic level controls and roll off the bass to make voices clearer. That's great for their intended purpose but not what you want for recording your band or bass generally. Try a new memory card if it's just a standard card.

you could try bolting some finned heat sink to the aluminium chassis as close to possible to the amp to increase the cooling. Smear it with a heat conductive paste first. This is the sort of thing http://www.rapidonline.com/Electronic-Components/Heatsink-159-X-200-50-0159/?source=googleps&utm_source=googleps&gclid=CIeHpe2wjb4CFQcTwwodgzoAKg though you will need to look for something that is as good a physical fit as possible. look for the lowest thermal resistance you can find. It won' be as good as mounting the amp directly onto the heatsink but it should help a little without too much surgery on the amp.

Great, that's the deal. free advice for telling us how it comes out.

Oh of course you might be able to improve the cab with some judicious stuffing and adding some bracing to the panels, the betas aren't great speakers but they aren't the worst either.

You don't say what your 2x10 is, if it is a home brew then it isn't going to sell for anything much, the drivers would sell for more on their own. If it is a reasonably well known brand then you would probably get enough by selling it for that to be the cheaper route as everyone has said, there are some real bargains to be had used. If it is a reasonably well made home brew and you are determined to tinker anyway then there are better speakers. For £50ea the Beyma SM110 is a bargain, well made, good excursion though you'll have to wait for delivery at the moment as they are imported specially from Spain. For £60ea there are the Fane 10-300 pro's which i've used. Very strong controlled bass but very neutral top end so they lack sparkle. The eminence deltas are £65 here and are a bit better than the Betas but not as good IMO as the Beymas. For £95 you have the Celestion BN10's (neo speakers) and the Eminence basslites are £90. I'd go for the Beymas or the Celestions. So for £100 you can improve your cab and for £200 you could have quite a good cab with modern lightweight drivers. Hmmm I feel a purchase coming on, rather like those Celestions. You'd probably need to re-tune the ports and check the size of the cut out holes. Look to see what you could trade up to used and then decide

There's a lot of compromise in any speaker design and where you end up depends upon opting for a design philosophy as well as doing all the tests and calculations. We haven't debated this in public yet but one of the issues we are looking at is tuning. I want to tune the cab for the lowest excursion at low frequencies, something that will handle low B fundamental at a couple of hundred watts. Stevie wants it tuned higher for maximum power handling. For most people neither of these would be the issue you might expect, I doubt you'd be pushing these speakers to the extremes they would get in testing or be able to hear a difference. The same is true of cab rigidity past a certain point. Bracing of whatever sort follows a decay curve, a little bracing will dramatically improve the sound of a cab, adding an extra brace to an already well braced cab, hardly at all. Sooner or later you will reach a point of diminishing sonic returns at a cost in time, effort and weight. The philosophy behind this cab is to make it easy to build, whilst sounding as good as possible. I'm thinking of a first time builder who wants a practical cab at a better price than an equivalent commercial cab. At the same time there will be no secrets so it is open to anyone to go for a 'better' driver or better bracing if they have the inclination. I hope a lot of you will be very happy with the sound of the basic cab.