Phil Starr

Hi again, I'm not sure about that data sheet, it does say preliminary data sheet though it also looks like it cae from Beyma. I really don't think a magnet of that size could give a Q that low, go with the figures in the link I gave you, which did come off beyma's site and which did work when I built the cab.

Actually this is nothing unusual. Lots of people use a Sansamp and a monitor. I've been using a Hartke kickback for my onstage sound for about a year. I bought it to do folky stuff and to use as a practice amp but you've got to try it so i took it along to one gig. I roll the bass back on the hartke to give it a bit more headroom and then compensate with a little extra bass through the PA. You get to hear the deep notes from the PA and having an articulate little speaker behind you pointing straight at your ears means no trouble hearing rather better than a conventional stack. I don't really need to feel the bass, just a taste thing I suppose. The biggest bonus is that everyone else turns down as a result and there's far less stuff from the backline going through the vocal mics. Got to be worth a try, there's more than one way of doing things.

Hi I have different figures for the SM212 Vas 150 and Qts 0.38. Cut off frequency is a bit of a misnomer it is just the point where the output is down 3dB it will go on producing sound below this point. At this point i'd use winISD so you can model the output more accurately. Generally lowQ speakers 'cutoff' at a higher frequency but keep producing sound quite low whereas highQ speakers like the Alpha will cut off lower but very sharply. WinISD will show you this, It has the parameters for most Eminence speakers in already so you can mess about with changing things like box size without needing to enter data for these speakers. As anyone who uses an Ampeg 8x10 can tell you a speaker that doesn't go down to 40Hz can still sound quite bassy. Most of what we hear are the harmonics not the fundamentals.

OK I said I'd look at choosing a driver. Now I have to be honest and say I don't know exactly what a driver is going to sound like from a spec sheet alone. However having an understanding of the specs and a bit of experience gets me 80% there. A very simple approach will rule out the real duds and that is what I'll try to explain. I'm not going to use algebra but to really get any deep understanding you'll need to get to grips with it or trust the computer to do it for you. Basically if you know how heavy a cone is, how stiff its suspension is and how much air it is pushing against and add in the springiness and mass of air in the box you can work out how far the cone moves for a given force at a given frequency. If you know all about the magnet and the coil you can work out the force so for each frequency you can work out the sound level. If you get it right the box volumes and the speaker match up, called an alignment, and the output is more or less the same at all frequencies. (the engineers and scientists are probably going to shoot me down for over simplifying here ) OK to choose the speakers I'm going to look at four parameters only, Vas which roughly says how hard it is to move the speaker cone Qts which is all the mechanical and electromagnetic factors lumped together, Fs is the resonant frequency and says how low the speaker will go and Xmax which is how far the cone can move before the coil leaves the magnet and is the true measure of how much power the speaker can handle. Now the speakers I am going to look at are the Eminence Alpha, Beta, Delta and Kappa (what happened to Gamma?) Alpha fs-49Hz Qts 0.77 Vas 121.5 Xmax 2.4mm Beta 47 0.46 120.1 4.4 Delta 55 0.43 81.3 2.4 Kappa 45 0.27 112 3.2 All the specs are here http://www.eminence.com/pro-audio/american-standard/?size=12#speakers you need to download the PDF's Now you could just plug the data into win ISD or do the sums but if you can find an alignment chart, I haven't been able to find one on the internet but most books on speaker design have them. Basically for each value of Qts there is a fixed ratio between box size and cut off frequency. Low Q means a smaller box and a higher cut off frequency. Q of about 0.4 is ideal for reflex enclosures. So the alpha has Q=0.77 which is too high because it has a titchy magnet. this means the box needs to be roughly 3x Vas (360l 0r 12 cu ft) for the best response which still has a huge bass hump of over 6dB. You can put it into a smaller box but you are going to make the bass hump even bigger. This speaker just isn't suitable for a reflex design and the magnet is too small to even make a decent sealed cab really. It's a dud. The Beta has been redesigned recently. Q is ).46 which my table says means box size is Vas/1.03 or 120l which is big but practicable. The bass peak is 1dB which you will just notice. The cut of frequency is fs/0.97 or 46Hz which is OK too. Put it in a smaller box and you will get a bigger bass hump and cut off will rise a little but this speaker works for me. The Delta is a missed opportunity for me. They've added a bigger magnet but stiffened the suspension. this has raised Fs to 55Hz. The lower Vas and Q means the box size comes out at 70l with a bass hump of 0.5 dB which yoiu won't notice. The big problem though is Xmax of 2.4mm, this means the coil will move out of the magnet at relatively low powers and the speaker start to distort with any real bass. The kappa has a huge magnet, Q is now 0.27 and my design table says to divide Vas by 3.17 to get box size or 35l. the big magnet means a compact box. Unfortunately making Q so much lower than 0.4 raises the cutoff frequency which is Fs x 2.15 or 97Hz. This is too high for a bass cab where bottom E is 41Hz.. Xmax is 3.2mm which is still fairly poor. This is a speaker which would be much improved by having a longer voice coil and different geometry giving a better Xmax and a better bass performance at the expense of sensitivity. So I've surprised myself by coming down in favour of the Beta, the best of this group though it needs a fairly generous cab and will still have a warm and woolly bass hump. I might put the Deltas into winISD if I was bored but the other two are not worth looking at. I wouldn't buy any of these. So far I've only looked at bass response but that alone has narrowed the search. If Qts is outside of 0.3-0.5 fs is over 50Hz or Xmax less than 4mm I won't look any further because I am unlikely to be able to engineer a decent cab. If Vas is too big then the cab will have to be correspondingly large so that's a side issue too.

[quote name='Mr. Foxen' timestamp='1360376186' post='1969684'] Out of stock mind. Not spotting them anywhere else with half arsed effort. [/quote] Ah, I forgot to mention the other problem, Blue Aran order these from Spain and they take ages to arrive. [quote name='Musky' timestamp='1360395397' post='1969712'] I'm certainly no expert, but doesn't stuffing a speaker into a smaller than ideal box create a hump in the low mids - which seems to be what the OP is looking for? [/quote] If that is what he is looking for then yes it will create a hump. Just needed to mention that when designing the cab it is one extra constraint. Mainly I wanted to give an idea of how to look at T/S parameters in choosing a speaker. Qts of around 0.4 gives you a chance of a flat bass response but Vas of 150l means a bigger cab. My speakers are in a considerably undersized cab which, sure enough, gives the hump you mention.

Just off to bed but OK then. I'm not sure what sort of sound a Berg makes so if you find me a link to a good recording or you or someone else can describe it I'll be able to get close. If you can find a frequency plot that will be perfect. In the meantime there's a 12" speaker that is a real gem for bass that I actually use when I'm not DI'ing, the Beyma SM212. http://www.bluearan.co.uk/index.php?id=BMASM212&browsemode=manufacturer http://profesional.beyma.com/pdf/SM-212E.pdf Why would I go for this? well Xmax is conservatively 7mm, tht's how far the cone will travel without distorting. This means that you won't lose output because the coil has left the magnet gap at high power. 2. there's good output up to 5,000Hz so there's plenty of top end there without a tweeter. This is done without a huge peak in output at 1-2kHz that a lot of the Eminence designs display. (not necessarily bad but it does colour the sound.) 3. Fs is lowish so you'll cover fundamental bass down to 40Hz 4. Qts is 0.38 which makes it relatively easy to tailor the bass to give a flat response. 5. It is nicely made with a cast chassis, sensitivity is OK too The only problem is that for a 12 it does need a fair size box ideally. The sound with bass is pretty open and clean sounding, you hear the strings coming through nicely. Bass is clean and deep without being boomy, just well controlled. Because of the excellent top end response you hear lots of detail too but without the Eminence cone break up the speaker doesn't add too much character of its own. I'll talk you through the Eminence and Fane ranges and try and predict strengths and weaknesses for you tomorrow. I've used both quite a lot but nothing matches the Beyma at this price point at the moment IMO

I feel for you a bit, not that the expert advice is wrong but it isn't very helpful. There's nothing wrong with the up-front recognition that a ceramic magnet is going to be cheaper than a neo for example. First of all there is nothing wrong with 12's but what people are saying is that the sound isn't defined by diameter, 12's, 10's and 15's overlap in sound however you have to start somewhere, so lets assume you will build a 12 and that you aim to learn about speakers by doing this project. we all start somewhere. First of all can I ask a question? Are you doing this because you think you'll get your dream speaker, because it will save money or because you want to learn? You won't get your dream speaker because you won't really know what yours will sound like until you try it out, by then it is too late to change. You might not save money either, you can't source the speakers as cheaply as the main manufacturers or the other parts, the best way of saving money is to buy used, then you can try what you are getting and sell it on if you change your mind. You will however learn loads and end up with a giggable speaker if you listen to some of the advice. I'd advise building a 1x12, if you like it you can build a second, if not you've only paid out for one speaker If you still want to go ahead let us know and we can start looking for what you want.

raising the cab will have two effects. Putting the cab at ear level will mean you will hear more of the upper frequencies and hence tell you more about how you are playing. It will also sound louder to you relative to the rest of the band. Secondly having the speaker on the floor means the floor acts like a big sonic mirror giving you an extra 3dB of bass. Moving it this high will reduce this effect and also cause some frequency dropouts dependent upon the height. Your audience will hear a bit less bass. Probably this will all just clean up your sound but you might need to eq differently and if you lack power floor and wall reinforcement is useful, Try it but as others have said a cab stand may be more practical.

You can definitely do this but you wouldn't expect authoritative bass from any old bass speakers and you shouldn't from any old PA speakers, you have to use something to do the job and choose just as carefully. Generally cheap speakers have smaller magnets which means sensitivity (how loud) and bass handling have to be compromised. you can have loud bass which runs out of steam at really low power or you have a speaker which handles bass but isn't as loud as a fully specced speaker. The amp in this isn't usually the issue, amp watts are cheap. the other issue is sound, some people like the clean sound of bass through the PA and others use a tone where the natural distortion of their dedicated bass speakers is an integral part of what they try to achieve. What's your taste? Decent stage monitors/PA speakers can surely give you a good sound and plenty of volume but I doubt those Behringers will. My 15" Yamaha monitors sound great but they aren't cheaper than a proper bass speaker, just different.

You don't need to worry about a speaker being 'too many' watts, you can drive a 1000W speaker with a 1W amp if you want, it's the same as turning the volume down. I'm not sure you have the speakers right, Eminence don't list a Beta just the beta A. Certainly a beta won't handle 600W. I suspect they are the same speaker and one advertiser is quoting its RMS power and the other its music power. There's lots better speakers out there, though this may be a good enough match for the Ashdown speaker. Are you replacing to upgrade, or has the original blown?

I think icastle has it. jack plugs weren't really a standard size and there used to be considerable variation so some pugs will just make better contact than others, replacing the output socket will help but you might improve things by using a spray of switch cleaner onto the socket contacts, Find a plug that works and make up a speaker cable with that. I find gold plated plugs do often make a cleaner contact but replacing the socket is the cure. If the crackle persists I'm afraid it could be any one of a number of caps or almost any joint inside the amp or even worn or dirty potentiometers.

To find the volume of your cab accurately you need to measure the internal dimensions of the cab and subtract the volume of the port but very roughly it is about 90litres which is about ideal. Unless your cab is really old and battered I wouldn't start using surgery yet. It is worth more second hand as an original cab. If you can get the back off easily you can mount the driver to the rear of the baffle (front panel), you might also be able to fix it (untidily and temporarily) in the hole for long enough to test whether you like the sound of the new driver. To do this just make the speaker frame seal against the cab with draughtproofing foam strip or possibly mastic, though this is messy.. Once you have started cutting the baffle you won't be able to put the original speaker back in if you prefer it to the Faital.

Specs are here http://www.adamhall.com/en/Faital_Pro_Professional_Series_-_15_Speaker_400_W_8_Ohm.html. These are good speakers, best suited to a cab of about 100 litres. The simplest thing to do would be to try them in your cab and if you like the basic sound to build a cab actually designed to go with your speakers. if you think building a cab is beyond you then look for a cab which has a circular port as these are easier to re-tune and it would be best to go for something between 70 and 100l. The Peavey BXBW would be good and you can pick these up for a lot less than a GB cab. (£50-100) You'd probably get £40 for the Black Widow driver on eBay so you'd get a substantial box for probably less than £50. If you decide to go this route I've actually got an old one of these which I'd happily sell empty, though it is up for sale with the original driver at the moment. Ideally I'd put these into a couple of light weight cabs custom designed though and take advantage of these neo speakers.

Sorry, but another vote for the AER Amp One

I used one of these (mk IV) and it gave a great sound.

For Promethean and clones http://basschat.co.uk/topic/168416-another-promethean-clone/page__st__240__p__1886279__hl__promethean__fromsearch__1#entry1886279

Having a back up amp is a great idea for any performing bassist though youcan always go through the PA so taking along a Sansamp or something similar would get you out of a hole. It makes sense for a backup amp to be cheap and light so look for one of the newer switch mode amps like the Promethean. There are cheap clones/rebadged versions of this in europe so look for similar in the States. Behringer is built to a budget, so less attention to detail and cheaper components but good design and value. Their PA amps are well respected though and seem fairly robust, I have two, never a problem. The amp part of the heads will be the same so as long as you don't get the last one made on a Fri I wouldn't worry. If I wanted just a backup amp for less than $200 I'd probably buy a used Peavey. Do the job and bomb proof.

[quote name='aende' timestamp='1358415163' post='1938603'] Interesting - I looked at the eminence beta too. I spoke to blue aran and they recommended a p audio driver..... This may be a suck it and see..... [/quote] Ultimately it always is, the problem with DIY is you can't try before you buy, but the more you understand the better chance you have of being happy with the result. [quote name='Bill Fitzmaurice' timestamp='1358431907' post='1939002'] You're not considering the most important charts, maximum power and maximum SPL. [/quote] Well that's kind of true but if it sounds s**t then being loud and s**t won't help any more than sounding great at one watt but exceeding xmax at anything like stage volume. [quote name='aende' timestamp='1358436333' post='1939108'] This is true - My budget is tight due to an ongoing job/house move - However, I did read this: [url="http://billfitzmaurice.info/forum/viewtopic.php?f=12&t=2357"]http://billfitzmauri...php?f=12&t=2357[/url] on your website Bill. Are Eminence Alpha 10's really a close match to the driver in the Ampeg SVT210HE cab? I am using the SVT210HE at the moment borrowed from my father-in-law. However, my 'new' cabs are similar in size a volume - peavey tx cabs unloaded tuned for 40hz with crossover and horn at 3500hz - 80 liters or 3 cu ft volume - ported at the rear. I have opted for the Eminence Beta as I prefer some low end. However, I am wondering if I could have used the Alpha...... [/quote] So have you ordered the Beta's? I was going to put the drivers into winisd for you but if you've ordered it is too late.

[quote name='aende' timestamp='1358355521' post='1937689'] Thanks Phil - I agree with you. I think I will run up one cab now and see how it goes. My thoughts are more towards the Eminence Delta's mentioned - they seem to be a bit more punchy. [/quote] If you compare the Delta 10A with the Beyma you are going to hear quite a difference. The Delta's have a huge cone resonance which gives a big peak in frequency response centred on 2.7 kHz. and a roll off at 3.7. This upper mid peak is going to dominate the sound and may well come across as punchy. There's a huge magnet for a speaker this size and that gives good control of the cone. On the minus side the cone is quite light (probably why it is peaking in the upper mids ) and the resonance is high for a bass speaker at 66Hz which is about bottom C so little fundamental for anything lower than C. The big magnet will roll off low frequencies too. Again this will give a lighter faster sound to the speaker. Having said that we don't really hear the fundamentals that well and really deep bass can result in a boomy sound in a lot of venues. If you compare this with the Beyma the heavier cone damps the resonance better and the mid range peak is smaller (5dB v's 8) more importantly the bass resonance is lowered to 43Hz, more or less bottom E. This speaker is going to have a modern sound with good control of deep bass, which is actually going to be there. The SM110 also gives more treble output. The biggest difference is in Xmax and Xlim, basically how far the cone can move before distorting and then damaging the speaker. Sadly they use differnt ways of expressing this with Beyma more conservative. I reckon the Beyma would measure about 6.5mm for Xmax compared to the Delta's 3.5mm meaning the Beyma will move twice as much before distorting. I haven't modelled these speakers but I think the Beyma will handle more power than the Eminences despite the thermal rating. The Beyma also has the plus of a cast chassis. There isn't a right choice here though, you just need to decide on what sound you want. The Delta has the sort of response you'd get from a guitar speaker at the top and less deep bass but could well give the sort of 'in your face' sound you want. the Beyma will be better behaved, if my 112's which have similar properties are anything to go by they are subtle and revealing. More Jazz bass than Ricky. Oh be prepare to wait for the Beymas though, they're Spanish and will have to be ordered by Blue Aran.

The problem with the driver you suggest is that it is very low sensitivity, only the same as a hi fi speaker so you'll need a lot of power to get the volume on stage. If you want to keep the costs down then these http://www.bluearan.co.uk/index.php?id=FANSOV10-125&browsemode=category will be louder as a 2x10 than both of your cabs loaded with these cheap speakers. The Fanes do sound good as bass speakers too. You'll spend about £100 on four of these cheapies, Spend £50 each on two better 10's and you'll end up with a better sounding and louder cab for the same price and you'll only have to carry one cab. If you love it and want even more volume then you can go for a second cab when you can afford it. For £50 you can get these. I use the 12" versions and they are fab sounding. http://profesional.beyma.com/pdf/SM-110%20NE.pdf there's also the eminence Deltas and for a little more the basslites to consider.

Oh, I was looking for some monitors on ebay this morning and there are loads of bins on there of all qualities. This is a good time to buy, people are skint after Christmas and the bidding is often quite weak

Punctured? if there is just a small hole in the cone you can repair it by pushing as much of the fibres back into place then layer up a small patch on both sides using Copydex (a latex adhesive) and tissue paper. It won't be as good as new but it does work and lasts indefinitely as a fix. Alternatively this might do the job http://www.faneinternational.com/downloads/FANE_Studio_5FRK_Specs.pdf

First the actual answer to your question is that you will be approximately 2dB louder with the extra 100w, 1dB you will just hear and 2 you will notice but not by much, a bit like just tweeking the telly a little. Generally at any given price point I's go for a 2x10. They are likely to be in a smaller lighter box and two speakers are going to be be lighter than 4 in most cases. If the overall price is the same the two speakers for the price of four are going to be better quality, again most of the time. Knowing the techie stuff helps you home in on what to look at but the most important thing is to try them out and choose the one that sounds best. 200W through a high efficiency 2x10 should be louder than the drummer

[quote name='stingrayPete1977' timestamp='1356785858' post='1913560'] So why does anyone have anything more than 100watts? Why do barefaced cabs get a reputation for being power hungry etc? [/quote] Amplifying electric guitar or bass is a matter of design philosophies and compromises. If you are amplifying double bass or an acoustic guitar then you are usually trying to get a 'natural' sound but there's nothing natural about amplified electric bass. All speaker design is a matter of compromise. For example you can have a speaker that goes deep, you can have a speaker that is efficient and you can have a speaker that goes loud but you can't have all three because they place different demands upon the voice coils, magnets and cones. I'll explain: To make a cabinet go deep you need to add weight to the cone and put in a long voice coil to get the extra movement. A heavy cone is harder to accelerate so the speaker is less efficient. The longer voice coil means most of it will be outside of the magnet gap and you lose more efficiency. To make a speaker more efficient you can make sure all the voice coil sits inside the magnet gap so all the electrical input is used, but as soon as you put a signal in it moves out of the gap and the speaker starts to compress and distort. the deeper the bass the more air you need to move so if you want to get efficiency this way you have to limit the bass response and the power you feed to the speaker. To get the cab to be loud enough you're going to use a lot of speakers or put up with bass being limited. The one positive thing you can do is to increase the size of the magnet, There's a limit to this though, partly because the cost gets to be extraordinary and also the weight becomes significant, Eventually you also have problems with saturation of the pole pieces and so it goes on. The advent of neodymium magnets has given us a bit more wriggle room and new opportunities but at significant cost. Designers like Barefaced have grasped the opportunities of new materials and cheap amplifier power. By using long throw speakers they can get more sound out of single drivers and they can get deeper bass without compression or exceeding the limits of speaker movement but the 'cost' is very good drivers, which are expensive, and long coils which are by their nature less efficient, This isn't a problem in a world where you can buy lots of watts for relatively little outlay. The big plus is a versatile sound and light weight. You could take a completely different design philosophy though. Since the whole sound of electric bass is artificial anyway then go for the distortion, embrace the 'natural sound' of 'under-powered' valve amps driven hard and the 'louder' sound of a short voice coil in a speaker with prominent peaks in the bass and mid-range. Valve amps are pricey so you are stuck with low watts or an overdraft but you can spend on extra speakers to give you more sound for your watts. You'll lose deep bass and your top end will be restricted by the problems of multiple drivers but you'll have the classic sound of rock and incidentally the look which 'modern' designs probably still don't quite achieve. These design philosophies are only two of the options though. BFM designs for example use horns to raise efficiency, which imposes a different set of compromises and there are other conventional designs which just set the compromises in different parts of the spectrum.