AndyKos

[quote name='alexclaber' timestamp='1380881394' post='2231813'] I'm not particularly appreciating being (mis)quoted to attack Blue Aran. As I said at the start of the thread the Kappalite 3015 is a great driver for bass guitar but as with all drivers it needs to be use appropriately. Put it in too high-tuned a box or too low-tuned and/or large a box and it will not perform as well nor be as robust because its excursion-limited power handling will drop well below its thermal power handling. Use it in the right context and it will not only outperform the vast majority of commercial cabs but will outlast them. To continue the Aston Martin analogy, this is a case of putting a Aston engine into something with completely the wrong gearbox/final drive, so to use it at motorway speeds you're running well into the red on the tacho, and there's no rev limiter (compressor/filtering) to protect the engine. The photos show horrible over-excursion damage. Either this was used in a very loud band where the bassist could barely hear his cab, or the bassist didn't know or care that those nasty over-excursion sounds were bad, or it was being used as the bottom half of a stack so the sound from the cab on top was obscuring the distortion. The 3015 starts exceeding 10% THD at 5.9mm excursion and that distortion rapidly increases as you push harder. Because the voice coil is leaving the gap it takes an ever increasing amount of power to push it all the way past the 5.9mm Xmax to the 11mm Xlim where the coil hits the backplate. Knowing how robust kapton voice coil formers are, the damage pictured doesn't look like it was one freak incident but repeated impacts - maybe only one loud bit of one song but those impacts were both hard and repetitive. It's user error, caused by putting a driver into the wrong cab and then being unable to hear the audible warning signs or ignoring them. Make the cab large enough and/or tune it low enough and it's surprisingly easy to ask too much of a woofer in the critical 60Hz range - that's how I wore out my Acme 10"s (though it took 900W per 2x10" cab to do it!) If Blue Aran were advertising "buy this driver to upgrade your bass guitar 1x15" " then they would definitely share the blame, or if they advised the customer that this was a good use for it. I don't believe that's the case, though please correct me if I'm wrong. It's horrible to see such a nice driver wrecked like this. If Eminence sell a recone kit (they do for some Kappalites) then it would be repairable for less than the cost of a whole new driver. [/quote] I havent taken any of your comments as an attack against us, in fact, everything youve posted that Ive read seems a very balanced assessment of the facts. The kappalite is repairable by use of a recone kit, last time I checked there was no stock of these in Europe, and they had to be ordered in from the US. If I were to hazard a guess the cost of a recone kit would be just under half the cost of a new driver, even with a charge for fitting this would be significantly less than a new driver. However that wont necessarily solve the problem here permanently, as unless the box is retuned, and other measures put into place to limit excursion and power, the same problem could happen again.

[quote name='Bill Fitzmaurice' timestamp='1380852549' post='2231589'] I agree to some extent, though it falls upon the customer to do the proper research to be sure that they are purchasing the correct driver for a particular application, not the retailer. I don't expect a retailer to have a high degree of engineering expertise. Of course, if the retailer does assume the position of giving applications advice, other than merely reposting manufacturer specs and data, then they have the obligation to be sure that they get it right. In short, don't offer expert advise if you're not an expert. Still, I put the onus on the OP in this case. I'd be curious to see exactly what research he did. For instance, did he ask here before making his purchase? [/quote] Most retailers do not have the appropriate level of expertise to give detailed advice, given that there are people that have devoted their entire lives to researching speaker designs, and there are numerous tomes on the subject of speaker design, it is not realistic for a retailer to have all the information available. It would be a bit like going to a hardware store to buy some bricks,sand, cement and some timber and expecting them to tell you if your planned build of a new house is to code and wont collapse, it's beyond the remit of most retailers to be able to offer that level of advice. Where possible, we do try to give advice and guidance to the best of our ability. We can certainly steer people in the right direction, and offer an opinion. We do have staff who have enough knowledge and experience to cover most of the basics, but it is not financially viable for us to offer an individual consultancy service on every single loudspeaker sale, it would simply be impossible for us to get a suitable return on the time taken to give the detailed advice.

[quote name='Mr. Foxen' timestamp='1380852479' post='2231588'] As I said, bandpassing is also used in Pa. Thing is, playing bass into a bass cab is a different thing from PA. The 'used correctly' is thrown out the window if the speaker is not being used correctly by being in an incorrectly tuned box. Compressors and limiters are optional for playing bass guitar, if you need one, rather than having a preference, something is wrong. Possibly the thing that is wrong is the tuning of your cabinet. Blaming the driver is entirely incorrect. [/quote] I guess my experiences are different to yours, and I am looking at things from a different angle, generally when it comes to bass guitars Ive been trhe other side of the mixing desk to the guitarist, with a PA system of 2500 - 15000W at my fingertips. We would always just take a DI out of the bass head straight into the mixing desk, and then insert a compressor limiter for some control, and the bass guitar sound would be reproduced through a 3-way system with dedicated subs, mid and high speakers - I guess this is what to you are referring to as bandpassing? Yes your bass guitar cab is different to 'PA' - but if you ever play bass guitar on a proper stage with a large audience, your bass cab becomes pretty much irrelevant and serves only to make sufficient sound on stage for you to hear and perhaps directly in front of the stage for the first line of the audience, for the rest of audience your bass guitar sound will be reproduced by the PA system, particularly in any outdoor event, a bass cab simply wont have the throw to reach past the first few lines of the audience. In smaller environments, where the Bass isnt going through the main PA, the cab's sound becomes more important, and the tone of the cab will be the primary factor with regard to the sound of the bass. Here the bass player will have more control over the sound using EQ, etc. In reality its difficult, some would argue impossible, to have a single speaker reproduce the entire frequency spectrum, there is a trade off somewhere. If you want a better mid-high response you sacrifice bass, and vice versa, this is why most loudspeaker solutions are multi-way with more than one speaker being using to ensure the full frequency spectrum is covered adequately. With regard to compressor/limiters, if you're running a 500W cab at around 50-100W in a fairly mellow small cozy venue, there probably is no need. But if you want to run your 500W cab at 450-500W I would say a compressor limiter is a good investment. Its possible to have massive dynamic peaks, of perhaps 10 times the average power, which the driver simply can not cope with, regardless of how well the cabinet is tuned. Reflex tuning optimises the bass response at the bottom end of the drivers frequency range, and if done right, extends the usable frequency range a little, done wrong, and it can spell disaster for the driver. Getting reflex tuning right does not offer any protection against excessive power, or massive dynamics.

recognising the name Bill Fitzmaurice,Im curious are you the same Bill Fitzmaurice thats linked to numerous speaker designs, or is this just a coincidence of name?

[i]Using compressors and limiters is standard in the music industry, its a good way of protecting speakers from being blown, used correctly it is virtually inaudible.[/i] [i]I dont see it as a bodge, its standard practise.[/i] [i]It is possible to run live music without compression, but for that you need a lot more headroom, and I mean A LOT.[/i] [i]Simply tuning a cab correctly doesnt protect it from being over driven. Tuning a cab correctly optimises the bass response, it is quite possible, and indeed common, for drivers to be blown in correctly tuned cabinets.[/i]

[quote name='Mr. Foxen' timestamp='1380843560' post='2231560'] Front of house is bandpassed to the relevant speakers for the job. [/quote] ???? Not sure I get your point??? Have you never played bass through a large FOH system?

[quote name='Mr. Foxen' timestamp='1380832557' post='2231391'] Not if you want some top and definition in your sound, and don't want to eq out a weird mid bump from using a driver outside its intended passband. [/quote] The mid bump on the Kappalite 3015LF is around 3-4 dB centred around 1.2Khz, this would be audible to some extent, and possibly add a very slightly aggressive tone to the sound, but Ive seen much, much worse response graphs than the 3015LF which is fairly flat up to about 1Khz. It fades away quite steeply above 2Khz, but its not that difficult to get a tweeter to fill in above this. Some people like more high frequency content than others, again I dont think there is a one answer solution here, it does depend on personal preference. A perfectly flat response is not necessarily correct, in 'hifi' world there is a general consensus that a flat frequency response is best, this is because hi-fi is being used to reproduce prerecorded music, and the idea of having flat response is that you do not colour the sound or change the sound from how it was recorded, and the 'hi-fi' sound is true to the original. In live music, a perfectly flat response may in fact sound dull and boring, and in some instance people will choose a cab/driver based on its tonal qualities, as they like the sound from a particular driver, as it suits their style of music. If there was a simple 'one size fits all' solution that was perfect for everyone, there would only be one speaker design, and one manufacturer and everyone would have the same, this simply isnt the case, there is more than one way to skin a cat.

[quote name='Mr. Foxen' timestamp='1380838921' post='2231486'] If what you are trying to achieve is a bas sound suitable for stuff other than dub/reggae, with a 3015LF, its a mid driver you'll need. Any driver needs an appropriately tuned box, and a high pass is a better thing for safety because a dynamics compresses, surprisingly, affects dynamics, which are a part of music, plus they increase the risk of thermal damage by increasing average power. [/quote] A high pass filter will help prevent over excursion, but is not an absolute guarantee of prevention. In this instance I believe a dynamics compressor would possibly have saved the driver, as the user has stated he has not applied high levels of particularly low frequencies. The driver did not fail due to excess average power, the failure was 99% over excursion, the burn marks on the voice coil are simply an indicator of the voice coil moving outside the magnetic gap and being unable to cool correctly. A dynamics compressor, used lightly, just to control the peaks and not completely squash the sound could have helped keep the driver within operating parameter. A compressor is not an all or nothing device, you can tweak it to get the correct desired result. You are correct that dynamics are part of music, but look in the FOH outboard of any decent sound enginner and you'll probably see atleast 8 channels of compressors. You often wont even realise they are being used, thats where you can differentiate between a good engineer and a bad one, there is a delicate balance between maximising volume, protecting the sound system and maintaining musical integrity. If you want to keep all the dynamics of a musical signal without any compression, you need to increase your available headroom to suit, this isnt always possible, so you need to reach a compromise. A combination of High Pass Filter and Dynamics Compressor, used CORRECTLY, can help prevent speaker overload, particularly in terms of over excursion.

[quote name='Mr. Foxen' timestamp='1380838496' post='2231478'] So that's two counts of Blue Aran staff not having the first clue about bass cabinets then. [/quote] You're entitled to express an opinion, I hope thats all this is intended to be, and not a statement of fact.

I will review how we present information on our website, with a view to perhaps encouraging people to contact us if they are in any doubt whatsoever as to the suitability of the product they are looking at. We can provide advice on suitability once we are aware of the intended application, and hopefully steer people towards the best choice. It is however difficult, if not impossible to provide information that is universally correct for all applications, there is no 'one size fits all' solution with regard to loudspeakers, and if we were to start going down the route of trying to provide very detailed application info we could easily reel off pages and pages of waffle which would most likely bore and baffle most readers, and there would still be no 100% guarantee that we could stop instances like this happening.

[quote name='Mr. Foxen' timestamp='1380838158' post='2231470'] 1x15s and 4x10s aren't really comparable, loads more everything with a 4x10, if stuff is otherwise roughly equivalent. That is why they are such a bad combination to mix. For clarity in the mids and easily sufficient low end handling capability the 3015 in an appropriately tuned box wins hands down. Adding a tweeter to a 3015LF will give you a two octave plus gap in the mids. [/quote] All im saying is different driver combinations will yield different results depending on what you are trying to achieve. Key thing with the 3015 is that it will need an appropriately tuned box, and in my opinion, a dynamics compressor to provide some protection. What you can achieve with a 3015LF and a tweeter will to some extent depend on the tweeter.

[quote name='Musky' timestamp='1380838093' post='2231469'] Just to avoid any confusion here, can you confirm that the pictures you've posted are of the driver in question and that you work for Blue Aran? Sorry if it's in your signature, but I'm using my mobile and can't see it. [/quote] Yes, the pictures posted are the driver in question, and I am representing Blue Aran. Im new here, so not sure how to put that in my signature.

[quote name='Mr. Foxen' timestamp='1380832557' post='2231391'] Not if you want some top and definition in your sound, and don't want to eq out a weird mid bump from using a driver outside its intended passband. [/quote] It does very much depend on the desired end result, one option for top end definition is to add a tweeter to the cabinet to improved HF response. My comment about the 3015LF being a better choice was purely in the context of it being better able to handle deep bass notes, and having a larger maximum mechanical excursion, and not necessarily from a musical point of view. It is common for for 1 x 15 cabs tend to be a bit bass heavy, and its not unusual for 15" drivers to lack mid range clarity, and to some extent the choice of cabinet you make is dependent on the sound you want. From what Ive seen a popular choice is a 4x10, as the combined effect of four 10" drivers gives a similar or better level of deep bass than a single 15, however, being smaller drivers they also retain the ability to delivery punchy bass and often can retain very good clarity on mid frequencies. There are numerous factors which can affect driver failure, and in the instance of a bass guitar, can include playing style, Im not a bass player, so Im not going to try to get into the finer points of this, but certain styles of playing have more dynamic range than others, and it is often prudent to make use of a dynamic compressor to reduce the risk of damage. In most instances, the power level from a bass guitar will not be the sole cause of failure in a driver, as the 'average' volume/power will be well within its operating capacity. A compressor can be used to take the peaks out which can exist when playing slap bass, the dynamics can be massive, and without a compressor you can be driving a speaker to within a fraction of its mechanical limits, a compressor will help control the dynamics to avoid this.

[quote name='redstriper' timestamp='1380734246' post='2229763'] I just bunged a kappalite 3015LF into an old Ashdown cab and used it for lots of gigs and practises over the course of a year with no problems. Then I put the same driver into a smaller Flite cab, where it sounded even better and it's been in there about 3 years, again with no problems. I never did any port tuning with rice, custard or anything else and it's the best sounding cab I've ever had. I must've just got lucky.......... or perhaps it's about to blow! [/quote] Kappalite 3015LF is a much better choice than Kappalite 3015 for a bass guitar cab. The two drivers are quite different, and intended for different applications.

[quote name='gjones' timestamp='1380735011' post='2229781'] This one probably [url="http://basschat.co.uk/topic/190368-barefaced-compact-vs-b-stock-speaker-in-dodgy-ashdown-combo/page__p__1850862__hl__kappa%2015__fromsearch__1#entry1850862"]http://basschat.co.u..._1#entry1850862[/url] And by the way my Kappa is still going strong. Frankly I think you've been unlucky. I think that the majority of people out there in basschat land, who have replaced the speakers in their cabs, have had no trouble whatsoever. Possibly because (purely by accident) their cabs matched the required parameters of the speakers they bought. [/quote] purely by accident may well be significant here. If you actually took a look at the level of science involved in trying to achieve perfect speakers and match them up with the correct cabinet to get the best possible results you would perhaps have some idea of the time spent designing speakers and why some speakers cost as much as they do. Doing the R&D on a new speaker design is labour intensive and can be costly, money that has to be recouped in the sale of cabinets.

Additional signs of overexcursion: In the picture you can see where the coil former is breaking up from having hit the back plate of the driver, this is caused by excessive excursion towards the back of the driver. This is ultimately the cause of the driver failure, as the mechanical stability of the voice coil has been compromised. Additionally it is possible to see blackening of the voice coil, although this did not cause the driver failure, it is very likely it will have failed to the thermal overload in the not too distant future. The blackening is where the enamel on the copper is overheating and starting to burn. Alll drivers are rated to a certain power when used within their intended operating parameters, using the driver within its mechanical limitations is part of this. The blackening is a clear indication that the duty cycle of the drivers movement has resulted with the voice coil being outside the magnetic gap for a considerable part of it's operation. Keeping the voice coil within or near the magnetic gap is a very important part of the cooling process of a driver, an overexcurting driver will be moving in free air instead of within the magnetic gap. Close proximity to the pole piece, and other metallic components in the magnetic gap is a critical to ensure sufficient cooling. If the voice coil is forced out of position due to over excursion, it can not cool properly. A DC Offset (amplifier fault) can also contribute to problems like this. My conclusion is that the driver in these two pictures failed due to over excursion, most likely due to incompatibility with the cabinet in which is was being used. However in addition to this, significant power would have been applied in order to cause the voice coil to blacken.

Signs of overexcursion: In the picture you can see creasing just inside the edge of the cone, this is caused where the cone is trying to move forward, but the edge suspension has reached its limit and wont let the cone move any further, initially the cone will flex a little to accomodate the additional forward movement, but ultimately will crease and fold as the forward pressure overcomes the mechanical strength of the cone.

[quote name='Bill Fitzmaurice' timestamp='1380630582' post='2228069'] +1. As is the case with any and all drivers it must be loaded into a cab that is compatible with its specs. If one is to push it to maximum output the amp must at the very least be appropriately high passed, if not limited to the driver's safe operating voltage swing. It must have sounded really bad for quite some time to have sustained the damage that it did. Distortion is the driver's way of telling you that you're pushing it too hard. In terms of performance the 3015 is on par with an Aston Martin. One would not expect Aston Martin to honor a warranty replacement claim should one drive it into a grove of trees. [/quote] I like Bill's analogy with the Aston Martin, however to me in this particular context it would be a bit more like pimping up your Aston Martin by going to the nearest Car Parts Dealer, buying some random engine components and fitting them, and when the engine blows up, passing the blame to the car parts dealer for not teaching them how to be a mechanic. In many cases it is possible to swap out a driver in a bass cab, and achieve good results, many drivers have a reasonable tolerance for being used in different cabinets with different tuning and the end results being without incident, this does not mean it will always be the case. There are a few key points you should be aware of if swapping out a bass driver: 1. Box tuning, your cab will almost certainly be tuned to a specific frequency, the ports in the front baffle work to complement the driver for which the box was designed. Around the resonant frequency of the box, cone excursion is reduced, and there is an increase in bass output. Without going into too much detail, the resonant frequency of the driver should be appropriate for the cabinet design, a wildly differing resonant frequency to the original can cause undesirable results. 2. With a reflex box, it is strongly advised to use a high pass filter just below the box tuning frequency, so if your box is tuned to 55Hz, you would want a high pass filter, preferably 4th order, to remove frequencies 54 Hz and below. Why? It's one of the side effects of tuning a box, at resonant frequency and just above you get a reduction in cone excursion, but BELOW the box tuning frequency and resonant frequency of the driver you get a MASSIVE increase in cone excursion, therefore it is imperative to remove the damaging low frequencies. 3. Replace with a driver thats suitable for your application, whilst all 15" drivers are capable of reproducing bass frequencies, some do it better than others, and some 15" drivers are tweaked for bass heavy applications, some are tweaked for general purpose application. A general purpose full range 15 is usually designed for use in a 2-way system in conjunction with a HF devices to run in a box for playback of prerecorded music and/or live vocals, etc where there is a mix of bass and mid evenly spread across the frequency spectrum. General purpose 15s are usually not designed for bass only applications. In this instance it would bhe prudent to note that there exists a Kappalite 3015 and a Kappalite 3015LF, the LF signifying Low Frequency suitability. The 3015LF has a maximum mechanical excursion of 17mm against 11mm of the 3015, this is significantly more distance before the voice coil/cone reach their limits. It is also normal in a LF model to have a stiffer suspension, which can reduce the cone movement for a given level of input power. A very lightweight cone, with high sensitivity and lighter suspensions as found in the 3015 is more suited to mid and high frequencies, the lighter cone and stiffer suspension can move quicker and faster, usually giving a cleaner sound and less distortion in vocals and mid frequencies. However, a lightweight cone will also be very responsive to the dynamics of live music, and the twang of a bass guitar will send the cone flying forwards very fast to the point it can easily go past its mechanical limitations. So in this instance you should be aware there is a significant difference between the 3015 and the 3015LF which is more than just a serial number.