Phil Starr

I'll have a go at the frequency response thing since both Bill and Stevie have brought it up. Since we have started with the Beyma and looked at the Eminence beta I'll look at these primarily and maybe take a sideswipe at the Eminence Delta [url="http://profesional.beyma.com/pdf/SM-212E.pdf"]http://profesional.b...pdf/SM-212E.pdf[/url] [url="http://www.eminence.com/pdf/Beta_12A-2.pdf"]http://www.eminence..../Beta_12A-2.pdf[/url] [url="http://www.eminence.com/pdf/Delta_12A.pdf"]http://www.eminence....f/Delta_12A.pdf[/url] Now the frequency responses of all speakers up to the point where the wavelength becomes shorter than the diameter of the speaker is better described by the computer descriptions than the measurements as these are affected too much by the measuring technique. Eminence tell you exactly the size of their anechoic chamber and the mic they use for example. Up to a certain point the sound is produced by the whole cone moving as a piston but as the frequency rises the cone will start to do two things, it will start to flex with the middle reacting immediately to the force from the coil whilst the outer edges lag behind. At the same time the cone will start to resonate as sound emanating from the coil cone junction reaches the outer edge of the cone and is partially reflected back across the cone. This all results in an uneven frequency response above this point which is about 360Hz for a 12" speaker. All three plots show a little dip in response at this point and unevenness above. Now this mess is a good thing for a practical speaker designer as without it the speaker would soon run out of hf response and would radiate high frequencies in an increasingly narrow beam. By controlling the thickness,shape and flexibility of the cone a designer can control the frequency response to a fair degree and even the join between the cone and the surround contributes to the response. On to the three frequency responses then. The Beyma shows a very flat response, on the frequency graph the response stays within the 2.5dB division from below 1kHz to about 4k. It is about 6dB down at 6kHz just about supporting the manufacturers claim of 45-6kHz. This sort of response is typical of a driver designed for PA use with a tweeter and I bought mine for this purpose as it makes crossover design easier. I tried mine with bass because, well I have to try bass through everything and found I liked the sound better than any of my bass speakers. Moving onto the Beta you can see the response is flat up to 600Hz and then rises up to a 7dB peak at 2kHz and is 6dB down at the 3.8kHz point. There isn't evidence of too sharp a rise in frequency response or a lot of peaks and troughs so the cone breakup is well controlled. This sort of peak is typical of many 'made for instrument' speakers and I think just about all of the Eminence bass speakers. So what does it sound like? Well it is going to give the midrange a lot of extra presence, it will cut through better on stage and I'd describe it as punchy. The trouble is for some people punchy is a slap round the ears and for others it is the gut wrenching sound of your stomach contents vibrating in sympathy with an Ampeg fridge so it is hard to know that you hear what I hear. Bill is probably right about it being part of the Berg sound and the Beyma doesn't have that sound The Beyma sounds 'cleaner' less cluttered, rather neutral sounding. I practice with headphones and that is the sort of sound you will get. It will go a little deeper than the Beta (and maintain the bass output at higher powers) but without a peak it won't jump out at you. The well controlled frequency response up to 6k is plenty to cover anything the pickups are likely to put out so you won't need a horn but the lack of the usual peak might not immediately appeal, of course you can eq it back in. Finally my sideswipe at the delta this has a ridiculous peak of 8db between 1.5 and 5kHz with a really sharp cut in and out and this will totally dominate the sound of this speaker. I suspect whatever you play through this you are always going to hear the Delta sound! Essentially it comes down to taste, if you like a bit of presence at the upper end of your bass and a little mid scoop, a speaker with a character of its own, then you may well get on best with a speaker with the sort of response shown by the beta. If you like something that is more neutral then the beyma is a good bet. Hope this helps and that the experts will let me off the couple of oversimplifications I've used

Sorry I posted thick with cold, I should have said I set the bass to 10 o'clock. Because I'm lazy about tone and because I'm a nervy performer I use the shape button quite a lot. I find I can change tone quickly and accurately with it. I tend to use it about 10 o'clock but roll it right round to get something like a Jamerson sound if the song needs it, That and switching it out gives me three tones I can find quickly in the gaps between songs. I quite like my little Hartke, which sounds awesome at rehearsal especially the 10 o'clock setting but I'm saving up for an AER amp one as the ultimate little solution.

You're getting some great support here! I'm rather boring in that I just follow the instructions on WinISD. What is interesting is that it kind of shows what the program is doing, Mms and Cms for example are the weight of the cone and the bendiness of the suspension and this immediately gives the resonance fs. Add in the SD, Bl and Re; cone area, force the magnet exerts on the coil and resistance and you can pretty much calculate how much air the speaker is going to move for a particular input. The other thing is the 'errors' that are thrown up by WinISD, the usual discrepancies are Vas and the efficiency figures. They almost never match the manufacturers spec. Not this time because they cheat, most manufacturers give measured figures from finished speakers. Vas depends upon atmospheric conditions and is horrible to measure consistently, efficiency is measured over the whole frequency range usually so often midrange humps boost the efficiency a little over the theoretical. Win ISD's recommended procedure. [color=#0000cd]The suggested procedure for entering driver parameters is following (check first that "Auto calculate unknowns" option is checked):[/color] [color=#0000cd]1. Enter [b]Mms[/b] and [b]Cms[/b][/color] [color=#0000cd]This gives [b]fs[/b]. If either is not available, then enter [b]fs[/b] and other parameter.[/color] [color=#0000cd]2. Enter [b]Sd[/b], [b]Bl[/b] and [b]Re[/b][/color] [color=#0000cd]Now, you should get all but [b]Qms[/b] (and [b]Qts[/b]), [b]Vas[/b]. Please note that Vas may not match exactly what is specified by manufacturer, because exact value of Vas depends on environmental parameters. See [/color][url="""][color=#0000cd]FAQ[/color][/url][color=#0000cd].[/color] [color=#0000cd]3. Enter [b]Rms[/b] or [b]Qms[/b].[/color] [color=#0000cd]Either one will do, although I tend to prefer [b]Qms[/b] over [b]Rms[/b], because it can usually be measured in driver measurement procedures.[/color] [color=#0000cd]4. Enter [b]Hc[/b], [b]Hg[/b] and [b]Pe[/b].[/color] [color=#0000cd]If [b]Hc[/b] or [b]Hg[/b] or either is available, then enter [b]Xmax[/b] and optionally either [b]Hc[/b] or [b]Hg[/b] if available.[/color] [color=#0000cd]This procedure is most accurate. Also note that it also calculates true SPL (1W/1m) value. So it might not match the marketing SPL value, which is generally somewhat vague. Not in all cases, though.[/color] [color=#000000]Hc is the height/length of the coil and Hg the size of the magnet gap. This is where the discrepancy between Eminences Xmax and others like Celestion and Beyma comes in. WinISD will calculate Xmax as if the moment the coil leaves the magnet gap controlled movement stops. In practice if you remember your iron filings experiments with magnets the magnetic field will extend quite a way beyond the magnet. Some manufacturers measure Xmax at a certain percentage distortion and others use a fixed proportion of the gap depth. Beyma are using the most conservative method so don't worry about this.[/color]

Hi Stevie I've looked at the Celestion and I agree it looks like a perfectly decent speaker, [url="http://celestion.com/product/39/bl12200x/"]http://celestion.com...ct/39/bl12200x/[/url] Like you I do wonder why they make the orange label drivers. The only reason I tend to refer to Eminence speakers a lot is they have probably the clearest data sheets, they produce a wide range of drivers and because their design philosophy seems to be stick any coil on a cone with all the magnet sizes they have lots of examples of poorly thought out speakers. I'll try and write something for 6v6 on frequency responses soon.

Stevie is right about the frequency response. Most of what we hear is midrange so that bass response is actually less important to the overall sound. What I've done so far is trawl through a few speakers to see if they will do the job. If Xmax is too small you will struggle to get good clean bass at decent sound levels. If the magnet is too small then it is likely to mean the cabinet will be too big to be practicable and so on. The next thing is very definitely to look at frequency response which gives you some idea of how it is likely to sound in a cab. I didn't mean to exclude the Celestions but there are a couple of things that concern me Xmax is low though confusingly they use a different measure to Eminence who are more generous in what they quote. Some of the Celestions also have a high cut off point when put in a cab but I've never modelled the 12's, just the 10's. I'll have a look at the Celestions tomorrow. Stevie is pretty knowledgeable about these things, he caught me out in my formulae on BC once I try to be accurate but the more you can learn for yourself the better.

[quote name='JPS' timestamp='1360918885' post='1978233'] I have used a Hartke Kickback 15" for a few years. Great amp when it's not being pushed, however, I've found that anywhere above about halfway and it struggles and the sound becomes overly harsh (perhaps it's the nature of the aluminium cone). I'm now back to lugging my Trace Elliott amp and Warwick cab/s around I'm afraid [/quote] If you are going through the PA this shouldn't be a problem, just roll off the bass on the Hartke. You can see how hard the speaker is working through the grille and I imagine the amp is using all it's power to do that. I find turning the bass back to two o'clock cuts the excursion dramatically and the distortion goes with it. Then I use a little bass boost on the PA to compensate if necessary. Since the bass from the PA is clearly audible on stage it doesn't sound unnatural for me either.

[quote name='BILL POSTERS' timestamp='1360692016' post='1974842'] Where theres room, any reason not to use a normal head and 4X10 + a kickback driven from the line out ? I like to feel plenty of Bass, but in pubs with only a vocals PA I cant always hear myself, or if I turn it up I cant hear the guitar. [/quote] Hi Bill, the arguments about getting rid of the conventional stack are all to do with reducing the on-stage volume. There are three good reasons to do this and some good reasons for using a stack, so I'm not telling anyone what to do, just looking at options. three reasons; You really don't want the vocal mics picking up anything other than vocals to get a good mix. A loud backline can be louder than the singer even though they are closer Excessive sound levels will damage your hearing, eventually you won't be able to play at all At high sound levels muscles in our ears contract to protect the inner ear so we hear less detail, maybe that's why you are struggling to hear everything. Of course if there is nothing to beat that adrenaline rush of really loud bass then stick in the ear defenders and rock, that's good too.

I use wire wool to get a matte finish on joinery with polyurethane varnish. I use 000 grade. the more zero's the finer it is. It's a lot easier to get an even finish with wire wool than wet and dry.

No, there's no reason why not though, other than we play a lot of small pubs with little space so against a wall is usually best. I tend to put it behind our drummer who likes to hear a lot of bass.

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