Phil Starr

[quote name='LukeFRC' timestamp='1415776932' post='2603566'] I am surprised there hasn't been more attempts to match good cab design to class D amps with DSP controlling multi band limiting and Eq to make powered cabs like the Bergantino ip series. I mean it's common in PA land- just not bass world yet. [/quote] It's clearly coming with combo's like the AER and it will soon be ubiquitous with combo's if only to protect the speakers from abuse. My belief is that is the main reason for putting DSP into PA. For manufacturers returns eat up their profits and having a computer in charge rather than an idiot 'sound engineer' means fewer returns. For bass it depends upon whether you like DI'd bass. I do, but for some people the speaker colouration is part of their sound.

Bill is absolutely right, there is no right answer. We may know what is happening to sound levels and excursion but which is best is a matter of judgement, experience or prejudice. That's why we talk about design philosophy, different designers might consider bass extension, flat responses or any one of a number of factors to be the most important overriding design concern. Given that not everyone wants the same bass sound a 'perfect' sound for one bassist wouldn't be right for another hence the disagreements about cabs in these columns. I'd agree with him about equal loudness too. Depending upon the sound levels and the datum point you use the sound at 31Hz might be 18dB down on what we still perceive as bass, add that to your 13dB and you would be 31dB down on your overall sound level. We just don't hear bass very well. Given the fact that you are in a band and there are lots of other things going on I doubt you'd hear any fundamental above the noise floor in most situations. To be fair against that the reflection off walls, ceilings and floors will reinforce bass output by several dB but I doubt you'd hear much of the fundamental anyway unless it excited room resonances, in which case it would be the room you were hearing not the vibration of the string. So. I guess my design philosophy, such as it is, is that the fundamental isn't very important and that for me I'm happy to lose a bit of output below 50Hz in order to better control the 50-100Hz range. I'd clearly go for the higher tuning in your case but that's not a 'right' answer, just my opinion. [size=3]BFM is indicating he would go for the lower tuning because of the extra excursion you'd get with a bit of eq applied, that's good reasoning too. [/size][size=4]I think your analysis is pretty much spot on, the question is what you do about it. In the end I don't think it will determine the overall sound of your cab and you'd only get cab failure if you regularly operate near the limits of the cab.[/size]

I started at 55, from scratch. Was playing pub gigs within two years. It's never too late! We're playing in Taunton next month http://www.lemonrock.com/gig.php?id=373404 Don't get disheartened if it seems slow at first, and learn whole songs. It's more rewarding and you'll want something you can play with other people sooner or later. There's nothing so exciting as the first time you play with other people and it sounds like music. Welcome aboard

The problem of the end user seems a much bigger problem than anything else to do with bass cab design!! As to your eq 'problems' I wonder if they are down in part to room acoustics. I've found that changes which are not noticeable in one room can become quite dramatic in another. Most of my testing is done in my 'music room' (don't tell my wife I call it that) which has a really heavy resonance right on bottom A, (it's 20' long) the slightest change in this area and the whole room booms. Unfortunately my eq centres on 64 Hz so I can't tune it out very easily. I only do A/B testing in this room now, and then further test in several rooms.

Here's to stubbornness! Test your thoughts to destruction then hand them over to someone else to destroy if they can, it's the only way to find anything out. (I'm an ex science teacher) I just noticed you'd used twice the square rt of 2 in your calculations. You have to make some assumptions and yours tie up with the TKS data and I've no experience to argue with them either so it all seems to be reasonable. The cone excursion is pretty much the main determinant of the max sound pressure levels down to 70Hz or thereabouts, depending upon the driver, and is much the same for a sealed or ported cab, you gain a bit lower down because the output of the port comes in (as you know, but others reading this may not) to supplement the cone output and the energy needed to excite the port damps/suppresses the movement of the cone. By tweaking the tuning frequency of the port you can alter the frequencies where max spl drops but you can't change the nature of the driver whose output follows the curve it would have in a sealed cab. Try modelling the same driver in a sealed and ported box in winISD and you'll see what I mean. So, I think if excursion is the limiting factor you need a second driver or a longer excursion driver. For me we set the design limit to be 120dB@1m over the majority of the frequency range as achievable and desireable. It will be interesting to apply your calculations to our cab to see if it will throw anything up. However with your cab design I see no problems except with a sine wave of 31Hz. Your simulation of an open B is 8.01mm with the lower tuning and although this exceeds Xmax it is well within the safe operating area of this speaker. You would expect a little compression and distortion for sure but I don't see that as a practical problem. It will be of a few tens of milliseconds in duration as you pluck the string and you will still get compression due to the ports and more so because of heating of the magnetic circuit at these power levels. Like you I want to know where the excursion is taking my speaker but I think this is more significant for reliability than it is for the 'sound' if you want undistorted 120dB bass from a fiver you really need two 12's not one.

You've probably been following the 1x12 design diary http://basschat.co.uk/topic/227904-1x12-cab-design-diary/ and together with the link to TKS above tht's probably most of the background on this site. I think this is a really good question and thoughtful analysis, and don't assume other people know more than you, just different. If you put something up which is data based then we should be able to answer it or at least offer a commentary. We've been struggling with this in the design of the 1x12. Given that most speaker failures are due to over excursion and that this was a home build project I felt duty bound to try and make sure we could spell out the limits of our design's performance. Tuning lower (40Hz in our case) enabled us to limit excursion at 31Hz but 50Hz gave us more control higher up, with more power handling and higher SPL (louder for the non technical) . Just as you have found. My instinct was to tune for reliability, the others for more sensible power handling and better SPL's in the 50-100Hz range. This is further complicated by the possibility of wind noises in the ports. Greater excursion means more air moving through the ports, if the ports are small and the port velocity gets too high this makes the ports 'chuff'. We reached a point where the port was too big to fit in our cab. In the end we plumped for the higher tuning and the final design will recommend the use of a high pass filter for some users. OK a question for you, how did you derive the fundamental/2.83 second harmonic/2 figures? Was this on the basis of some experiment or just derived from the maths? I don't think those figures are unreasonable as a rule of thumb, and they tie in with the data from TKS. My contention, without any data to be fair, is that the proportion of cone movement down to fundamental/second harmonic would vary between basses and between neck and bridge pickups. Essentially the further the pup is up the string the nearer it is to the antinodal point for the fundamental and the louder this will be. Where you pick/pluck will also affect this. Another factor is that of using Xmax as the sole basis for decision making. Xmax is defined in different ways by different manufacturers often as the point where the coil leaves the magnetic gap. However the magnetic field doesn't stop there and the coil will be in a gradually reducing magnetic field as it moves beyond that point with distortion gradually increasing. Eminence among others use this to offer higher advertised Xmax figures effectively at a fixed distortion level. However when you are talking about protecting your speakers then the maximum safe excursion sometimes called Xlim becomes more significant. Your speakers will function beyond Xmax albeit with power compression and increasing distortion. If this is brief in duration and at low frequencies I would expect that to be inaudible in a band situation, if limited it would be inaudible in any situation and the question becomes how much of this distortion is acceptable. I don't disagree with BFM about using the spl charts for decision making as it aggregates a number of variables and in a practical sense it probably doesn't make any difference to your design decisions, but I like to understand the compromises I'm making so I look at port velocities and excursion as well. I'm loving what you are doing.

I think it would be safer to say you [b]probably[/b] won't need to re tune your cab, which is done by changing the length of the ports. The cab looks like it is right in the middle of the size range for this size of speaker and they are usually tuned around 50Hz. However some of us will remember skidder swapping out his 15's for Eminence 3015HO 's and blowing one because he didn't check. A lot depends upon how you intend using the cab as well. It's a matter of minutes for one of us to check for you, so ask before you buy. Your cab new, costs £469 from Gear4music http://www.gear4music.com/Guitar-and-Bass/Hartke-215BXL-Bass-Cabinet I'd expect to pay about half that for a good used one so at £190 you would be in profit, just. There aren't many new drivers that would be a significant upgrade at £95ea

Another one for replacing the existing driver. Moving in a new driver isn't always as straightforward as you might hope and the cab will lose value if it isn't original even if the replacements are better drivers. This might just be an expensive way of buying a box. Self building is rewarding but you won't know what your cab is going to sound like until it is too late to change your mind. However if you do go ahead there are plenty of people here who will help you re-tune your cab. Be hard headed, find the cost of a replacement driver and the secondhand value of a working cab. If the cab is worth more that the driver repair it. Then decide if you want to sell and upgrade. If the repaired cab is worth less than the driver costs the repair is uneconomic, but you might pick up a used driver or an old 1x15 on evilbay. Alternatively if you love the cab and see one cheap..... You'll also get something for your old cab even damaged. If the cab is uneconomic to repair then you need to price up the cost of a couple of 15's (£60-200ea) and decide whether you want to take the risk on what they might sound like. Stevie is right by the way, speakers are often more repairable than you think. Put up some detailed pics and we might be able to suggest a repair which might gain you a year or two of extra use.

[quote name='LukeFRC' timestamp='1415055555' post='2596303'] hey! you 3 haven't even got a photo up on the 1x12 design thread yet and you're moving onto 2x10s??!!! [/quote] don't know if it is a function of the Y chromosome, my natural nurdiness or being a bass player but sticking to one thing??? I've got two basses I love and don't spend enough time with, that didn't stop me buying a third yesterday on a whim. There are photos of the prototypes on the thread somewhere, I haven't built the final versions yet, restoring my house, my new band and the death throes of my old band have absorbed so much of my time recently. I've vowed to get something out by Christmas.

[quote name='Beer of the Bass' timestamp='1415009480' post='2595481'] There's some interesting reading here. Alongside the low end response, I'm curious about the sort of colouration Phil refers to earlier which the SM212 and 10-300 apparently lacked. I'm another player who enjoys speakers with that peak around 2-4K and will often try to EQ it in if it's not there. If this does become another design diary thread it might be useful to suggest driver choices to bring that colouration alongside the flatter options. Would I be right in thinking that the Celestion has the most of this among those three? [/quote] Cones need to flex to reproduce higher frequencies and a flexing cone has its own resonances so once it ceases acting as a pure piston it is hard to control the frequency response. Most guitar and bass speakers have peaks in the frequency response above 1kHz up to the 3kHz region, which also corresponds to the point where our hearing is most acute. At the very least we are very used to this classic guitar and bass sound as most of the recordings in the formative years of pop and rock used these speakers and generally we quite like it. Ironically I run through mainly flat speakers but dial up the classic weak bass, bass hump, and 1-3kHz hump of cheap speakers on the eq because I like the sound. Both the SM110 and the Celestion exhibit this 1-3kHz peak but the Fane doesn't. The SM212 is an odd one because although fairly flat it gives a substantial output up to over 5kHz, -10dB is 6000Hz ish from memory giving almost an extra octave. I'm hoping to try the Eminence Beta in the 12" cab to try an old school sounding speaker.

Stevie may not know it but he is probably designing the new Basschat 2x10 for us. Looking at those frequency plots I'd say from that information alone these three speakers would sound significantly different. Interesting not knowing which is which. It's a kind of blind audition. The yellow trace is fairly flat at about 95db across the frequency range, down to 94 dB @ 80Hz and with maybe a 1dB hump just above 100Hz. The green trace is around the 91db point at 80Hz rising gently to 100db at 2000Hz. That's going to mean an audible difference. I'd really expect the yellow speaker to sound more bass voiced and the green speaker to sound louder and 'lighter'. Which isn't to say one is better than the other or that the difference is going to be dramatic. Green speakers long gentle bass tail off might even be useful in not exciting room resonances in some gig situations. So, yes, I'm happy that the Celestion models better than I expected. I'd still choose the Beyma personally but I did dismiss the Celestion too easily and maybe Stevie we can test one against the other sometime. Interesting

This is going to sound harsh and isn't [size=4]meant to be but this all looks amateurish. No PA? you really need to be self sufficient and able to show that you can generate enough money to buy all the essentials of your trade. What would you think of a carpenter who turned up without chisels or a plane? A video with a static camera and no editing and room acoustics evident? Have a look at this from one of our local bands and you'll see the difference [/size][size=4]https://www.youtube.com/watch?v=tOmU_iVy4s8#t=75 or at a lower budget level but still a good video [/size][size=4]https://www.youtube.com/watch?v=7-iJbyKKbM8. [/size] [size=4]You guys are great musically but there is something missing and for me it is a sense of theatre or performance. Skimpy clothes or a killer guitarist might do it as has been suggested but there are plenty of other ways of selling yourselves as entertainers. Sex sells, but It's not a route many of us would choose to take, however you do need to look as if you can entertain the audience you are aiming at.[/size] [size=4]Bandleading IMO is the missing ingredient in most bands. It's about realism and seeing yourself as others see you, and about understanding the needs and expectations of your customers. Cruise ships like everyone else are going to be looking for a hassle free package, and someone appealing to their customers. If your video is your main marketing tool does it promise that?[/size] [size=4]Good luck[/size]

Fane describe the 10-300 as having a 'smooth' response and it is flatter than many 10's, most have a fairly prominent peak in the 1-4kHz range which gives the speakers colouration which sounds quite nice with bass, or maybe that peak is so ubiquitous we have just come to expect it. My confession is that I'm going out with the SM212's which are fairly flat but my graphic looks like the frequency response you get from a cheap Eminence stuffed into a too small a cab. The 10-300's just didn't sound very interesting with bass. Nothing wrong but they just lacked character.

I went straight from 1000 to a burnishing cream with excellent results, but I glued the wet and dry to some flat board I cut to about 3x4cm before each sanding. Without this it's hard not to create a rim round each repair which shows the join. If the finish is otherwise good only use the burnishing cream to match in the rest of the finish which may have discoloured thus showing up the repairs.

[quote name='Leslie77s' timestamp='1414316306' post='2588048'] I don't hate anyone or anything Phil. Just a thought, an opinion, nothing more. [/quote] No I get it, which is why I thought your initial post was particularly well judged.

[quote name='88reaper88' timestamp='1414165910' post='2586663'] Might just buy a Harley Benton BB210T cab... Works out cheaper [/quote] If what you want is a cheap entry level cab and to just get on playing then you won't be able to match these prices by self building. By the time you've built the cab it'll cost you £50 add in the speakers and you are looking at £150 min. You won't beat Chinese mass production in building a cheap cab.

Theile Small calculations are fantastic for modelling the bottom end but tell you almost nothing about the way a cab will sound. I built a cab with the Fane 10-300's and at the bottom they sound as predicted, really rather good but, the trouble is they are so neutral at the top end they sound rather dull and boring, they don't go particularly high either, I've bought a 6" to try to add something to this cab but I haven't got round to trying anything yet, they make nice PA monitors with a decent horn though. In the end I swapped out the 10-300's for Fane 10-125's which sound much nicer, unfortunately Fane have since changed this speaker into something I can't imagine anyone using, God knows why. Funnily enough I was drawing up a shortlist for a 2x10 today and thought the Legend BP102 worth a second look, I also thought the Basslite S2010 looked interesting but is likely to be expensive over here.

[quote name='Leslie77s' timestamp='1414262543' post='2587736'] I struggle to like ageing multi millionaires discussing their difficult creative processes and describing how arduous making an album in lovely studios with the best equipment available was. However, since my unwanted U2 gift arrived I have discovered it contains some drivel but IMO Every Braking Wave is a song crafted simply and cleverly with fantastic vocals that unfortunately demonstrates that the old buggers have sold squillions of albums and have the right to tell my sorry working mans ass to F off with my opinion. I'm not jealous. Honest. [/quote] *Like* I've never really understood the hate for U2 or Bono, or any band really. U2 are fairly limited musically but good at what they do. They turn out a couple of good songs every album and over the years that's a fair no of good songs and gives a lot of people pleasure. Very few bands really change their style much over the years so why do they get criticism more than others? Preaching? Well which of us doesn't know how to put the world to rights and is reluctant to express an opinion? At least the guy cares and is prepared to put his fame on the line. I'm sure I'd sound a bit of a dick if everything I said was recorded, played back and picked over. As for Jools interviews, well they are always like that, aren't they? What were they going to say? "It's a piece of p**s, we can go on churning out this stuff forever".

Stevie strikes again Now I'm going to have to run the models and investigate a bit more. I'd looked at Qts and Fs done a quick calculation of f3 the -3dB point and left it at that, dismissing a speaker that starts to roll off albeit gently at 150Hz ish. To a certain extent it depends upon whether you think 3dB is significant or not. I think it is, as I find in listening tests that the balance between high and low frequencies is something we really notice. It's also true that the 3012HO has a gentle roll off due to a moderately low Q. Comparing it with another speaker would yield a different result. I'd also be interested to know what size box you modeled Stevie. I'm only getting a plot this shape for the Celestion in a fairly large box.

Congratulations Steve!

Now you are into the realms of taste really. Both speakers have a moderate upper mid peak which will enhance those frequencies a characteristic shared by most 10" drivers. Whether you like that sound or not and whether you need something to enhance the higher frequencies or are happy to have the speaker reduce the pick and string noise is something we all see differently. the trouble with building yourself is that by the time you try it it's too late to take it back.

Oh if you want something that does go lower than the Celestions then the Beyma SM110's look promising at a similar price. Be prepared to wait for delivery though [url="http://www.bluearan.com/index.php?id=BMASM110N&browsemode=category"]http://www.bluearan....semode=category[/url] There's a thread on here from someone (fleabag) who tried these speakers and had a positive result [url="http://basschat.co.uk/topic/235679-can-i-improve-my-cab-at-all/page__hl__beyma%20sm110__st__30"]http://basschat.co.u...20sm110__st__30[/url]

[quote name='Jenny_Innie' timestamp='1413993810' post='2584574'] Sorry, I'm new here. I don't get this. I have an Ashdown MiBass 550 .... which puts out 550 watts at 4 Ohms - but probably only about 300 and something at 8 Ohms. So ........ surely, there will be a higher volume at any given level on the dial if it is a 4 Ohm rather than 8 Ohm? I'm interested y'see as I'm kinda slight and would like a lightweight cab ..... and any help with output would be good. [/quote] Hi Jenny as everyone has said doubling the power gives you an extra 3db which is like turning your amp up one notch, not like doubling the volume. If you want detail go here, its a little technical but I hope straightforward http://www.ultimate-guitar.com/columns/gear_maintenance/making_it_loud.html The point is that some cabs can make more use of power than others. This is measures in dB's per watt. The worst cabs for this might make only 90dB for 1W the best maybe 102dB for the same power, this is more than the 3dB you get by doubling the power. In fact you'd need 16x the power through the first speaker to make it sound like the second! The trouble is most of these super loud speakers are big and heavy. It is possible to get loud and light but these cabs tend to be expensive because you need a good quality driver with an expensive magnet system to achieve both these aims.

If you go on the thread above you'll find some data from TKS engineering about the distribution in power between the fundamental and all the harmonics a bass puts out. Those Celestions will have very little output below 100Hz once they are in a cab, which will raise the resonant frequency even higher than 79Hz. Basically you will have almost no fundamental in the bottom octave of a 4 string. However it is the harmonics which give us most of what we hear anyway. Putting these speakers in a small cab will give a big bass boost in the 100-200 Hz range which will probably make them sound bassy or boomy depending upon your standpoint. These speakers are going to have a very 'old school' sound, lacking in deep bass and a bit indistinct in the bass area but possibly warm and punchy. Deep bass is often quite an embarrassment in a lot of rooms with poor acoustics creating a lot of boom as they excite room resonances so it isn't all bad. Because of the high fs and the fairly limited excursion of these speakers you'll need to limit the deep bass going to them, I wouldn't use any bass boost and think in terms of deliberately filtering out the low bass with something like a Thumpinator. As ever the advice is the same, if you are doing this to get a cheap cab then buying used is a better bet. If you just want the satisfaction of using something you've made yourself and to start learning about how speakers work and are prepared to take a risk on how they sound then welcome to the club.

OK this is entirely from a technical point of view. I haven't used these speakers. A 15" speaker has roughly 60% more surface area than a 12" so at the bass end will be louder assuming all else to be equal. Ignore the power output of the amp. These amps will drive both speakers way beyond what they can handle at low frequencies but the built in software protects the speakers so they are pretty bomb proof, if you do overload them they just gently turn themselves down for a fraction of a second and you probably won't ever notice this happening as the effect is subtle. The whole thing is engineered to squeeze everything out of the speakers by giving more power than is needed and controlling it carefully so the limits are of the speakers not the amps. When you are playing outside the bass is radiated 360 degrees, (actually in a sphere). Indoors walls, ceilings, floors all reflect that sound back to the audience and increase the bass, usually by about 6dB, the equivalent of using 4x the amplification. In addition you usually find people spread out more so you need maybe 10x the power and much bigger speakers to maintain the same sound. I don't think you can afford to carry a no compromise PA capable of giving the same sound at an outdoor gig. The 12's aren't going to be enough outside, the 15's a bit better but nowhere near enough. If you are the bassist then I don't think you would expect to get a lot of bass out of a 2x12 without PA support outdoors, though it would be perfectly adequate in most venues. It's pretty much the same for your PA, in fact it is exactly the same. I'd go for the 15's but I don't have to carry them. The decision is down to convenience though, 95% of your gigs you'll hear no difference. For the outside gigs you'll get the extra 60% of deep bass to help towards the 400% extra you'll need to make up for what you lose due to room reflections. If you take a bigger bass stack and turn the PA up full you won't be far off your indoor sound and it will be better than the PA tops on their own