Phil Starr

Everything decays eventually but speakers are fairly resilient. the biggest problem is likely to be damp. Small amounts of moisture will make the paper cone swell over time and eventually may cause it to distort. Larger amounts of damp may allow fungi to flourish. make sure you store it somewhere dry and if you have open ports in the cab block them, I've found mice in one cab I stored in a garage once I heard them moving when I set up and they ran out at a gig when we started playing

Last bit of advice, choose an amp on the way it sounds not the spec, that's a nice amp you have so only upgrade when you are sue what you have is better. Good luck, it's fun looking.

The first two options are both good, really follow Bills advice on bridging and don't. power wise I don't think you'd find any difference between one per channel and two. 312.5W and 350W aren't going to be noticeably different and frankly it is only 625W into 4ohms because the power supply limits your amp to 625W. I'd run one speaker per channel that gives you the chance to balance the outputs, If a channel went down you'd still have sound and you've reduced the current going through your output stage meaning that amp will run a little cooler.

[quote name='Bill Fitzmaurice' timestamp='1481819614' post='3195449'] Most amps have HP filtering built in. If yours doesn't it will be obvious by excessive thump noise, which is cured with a rumble filter. [url="http://www.gollihurmusic.com/faq/38-HIGH_PASS_FILTERS_GETTING_RID_OF_THE_MUD_AND_RUMBLE.html"]http://www.gollihurm...AND_RUMBLE.html[/url] Ported cabs are no more prone to damage than sealed. If anything you're more likely to over-power a sealed cab, as they have less sensitivity in the lows than ported. Ported cabs also have minimum driver excursion at Fb, where the port is doing all the work. Finally, xmax is not where voice coil damage occurs. That would be xlim. +1. If this was an issue reports of blown drivers would be rampant. [/quote] I'm writing this in response to a handful of people who don't know all you do who have blown drivers. No it isn't an epidemic but it happens regularly to folk on these pages and it is preventable. I'm thinking that one preventable failure is one too many and provoking some debate will help in understanding. I've kept the technical side down to a minimum here but speaker breakdown is complex, well a little anyway. The problem is not always overheating or always Xlim (the mechanical limits to excursion for those who don't do the maths) some of the cases I've looked into look like the result of thermal runaway where the coil is leaving the magnetic gap for significant periods meaning the temperature rises are greater than they would be using AES testing procedures. I've also suspected thermal compression is an issue when a speaker fails. the temperature of the coil rises and the sensitivity of the speaker falls ( I know you've spoken about this in past posts Bill, this is aimed at the interested onlooker) the response in the middle of a gig is to increase the power to the speaker and sometimes to boost the bass.

OK I've reserved this for answers/responses to anything you post up, I wanted to keep the original post shortish

Nowadays it is rare to see any bass cab around that isn't ported, but they all have a basic flaw which isn't widely advertised. If you don't know about it then you could end up with a large repair bill. Ported cabs for bass are generally tuned to 40, 50 or 60Hz , or somewhere in between. the way they work is simple. They are tuned to the frequency where the speaker starts to cut out as it's impedance rises. As the speaker cuts out it's output is replaced by the output from the port giving you very roughly a 3dB boost over the lowest octave. BUT you don't get something for nothing and the cost is what happens below 40Hz (or 50,60 or whatever, depending upon the make and model you use) . Below the resonance of the port the port just becomes a big hole in the cab. Down to that frequency the air acts like a weight and damper on the cone, suddenly that is all removed and the cone is free to move with little resistance. as a result any signal below 40Hz is likely to make the cone move way beyond the limits the speaker is designed for, even with just a few watts going through the speaker. With the coil outside of the magnet it rapidly heats up and it may even start drumming on the back of the magnet, either way complete failure won't be far away. Don't believe me? Try going to the Eminence website http://www.eminence.com/pdf/Beta_12A-2_cab.pdf and have a look at the designs they have for the Beta 12" speaker which is a 250W speaker. Have a look at the design for the large bass cab, they recommend only 75W into their 250W speaker and even so the graph shows the cone moving beyond its 4mm limit at 40Hz. this is a speaker widely used in Eminence equipped bass cabs.

Right, so little difference to my experience then. Thanks.

OK two cabs of 8 ohms is good that means 4 ohms load which will match any amp, just about. That means both speakers will get the same power, so if you did go for a 1000W amp both speakers would get 500W and there'd be a good chance of blowing the 400W speaker. The actual thermal rating of the two cabs is twice the lowest powered cab. 800W in your case. You are being given two other, possibly confusing, bits of advice: All the stuff about decibels. What people are really saying is that if your amp is loud enough you don't need more watts. If you look you'll see that most manufacturers have settled at amps that produce about 300W into 8ohms and 500W into 4. That will give you enough poke to be more than loud enough. Going to 1000W will only make you one notch louder (5000w would make you twice as loud!) and damage your speakers so not a good idea. In fact with 4 speakers in two cabs you will probably have a very efficient system louder than most of us use nowadays. The second advice is about excursion and watts not mattering. The trouble is there are a number of ways you can blow your speakers. That 400w rating is what will happen with a constant test tone based on mainly mid-range sound. You can measure how hot a speaker gets with a test tone and if it doesn't get too hot then that is the power it can handle. It's a system that works well for most speakers but not for bass. The other speaker killer is bass, too much bass and the speakers coil is pushed out of the magnet and may even hammer against the back of the magnet. A speaker that can handle 500w of midrange may only be able to handle 100W of deep bass, maybe even less. The trouble is that no-one can predict how much bass you like or what effects you use so no-one can say how much the power rating of your amp should be to be safe. All I would say is that most people using a 500W amp with 800W of speakers isn't going to have a lot of reliability problems. Anything less than that will be fine, any more and you had better start reading. It's all very well for an expert to push the boundaries but if you just want to get on and concentrate on playing knowing your gear is enough then 3-500W is more than enough.

[quote name='Bill Fitzmaurice' timestamp='1481730399' post='3194625'] One thing I learned long ago is that you can never assume that PA will be adequate, if there's any at all. [/quote]Most bands in the UK carry their own PA Bill, it isn't universal but I've only been to a couple of venues with their own PA. I gather from other forums that in the USA it is far more normal to use a house PA. Is that true?

You need to know the ohms of your cabs. They are more important than the wattage. If they are both the same impedance (ohms) they will share the power evenly. If not the power will take the line of least resistance and go mainly through the cab with the lowest ohms. If both cabs are 4ohms than you can only use one at a time with the majority of heads anyway. More when you come back with the ohmage.

[quote name='Happy Jack' timestamp='1481749328' post='3194902'] Try to swallow the resentment and part as friends. [/quote] This, I understand how you feel, you have clearly committed to this in a big way both in terms of effort but also emotionally. You believed you were a team and had each other's backs. You've found out that other people don't share your sense of loyalty, that some are incredibly self centred. Perhaps it is time for you to have a think about what you can get out of this. Firstly it would help you if the artist and the team would go around talking positively about the work you did. If it is to be released then you'd like thanks on any sleeve notes or publicity at the least if not an actual credit for production. If you ever work for them again you'd like to be paid for any future work if not for this. If things don't work out for the singer the way he expects then would you work for them again. If you can imagine any situation which would tempt you then why piss them off. You've behaved well and were sensible enough to put your studies first. Hold your head high, salvage what you can and move on. Next time you know what to expect and you can make sure you get agreements up front.

[quote name='Passinwind' timestamp='1481450162' post='3192299'] There was a long and sometimes contentious thread on Talkbass several years ago where many bases were tested with an eye toward spectral distributions. It's archived in the Amps Forum FAQ: [url="https://www.talkbass.com/threads/bass-frequency-waterfall-plots-what-they-mean-to-rigs.510749/"]https://www.talkbass...to-rigs.510749/[/url] In any case, boosting the fundamental in the way you mention most likely won't take that hypothetical 25% number to 100%, because the overtones still all have energy and therefore have to take up part of that 100% ceiling, and depending on what note you are looking at the bass control may well be boosting the first overtone or two just as or nearly as much as the fundamental. I'll be happy to illustrate this with an actual measured example or two when you start your new thread if you like. I don't do DIY speaker cabs any more myself, but I still enjoy doing the math. [/quote] I'll have a look at that thread later, thanks. OK guilty as charged I over simplified my argument to make it clear to the OP. Percentage of what? Obviously not of sound as stated, what I should have said was if the speaker was making 25% of the allowable excursion with the tone control flat then it would probably be doing 100% of the allowable excursion with the sort of bass boost he was applying. Tone controls are tricky things, there are a lot of different circuits used to control tone. Passinwind will vouch for that. A lot of tone controls are still based on the traditional Baxendall design. The trouble is this circuit will boost sound most the further you get away from it's first frequency of action, extreme bass is boosted more than upper bass. http://www.learnabout-electronics.org/Amplifiers/amplifiers42.php This means that when you boost bass to get a bit more warmth the subsonics are boosted even more than the bit you are interested in. Turning the bass control to 3 o'clock as the OP did is hardly extreme, but he may well have ended pumping four times as much power as he thought into his speakers. I want to help him get good results and to understand what may have happened but most of all I want to be able to offer the best possible advice to people who build these speakers. It's hard to explain situations where there are many variables in simple ways to the non-techy reader. Let's hope that when it gets back it is working as Blue Aran say it is.

There's only one answer to this. I'm as loud as the rest of the band. In practice that means being as loud as the drums.

I have the same problem, most of us do I suspect. We all want to be just a little louder than everyone else. Fortunately the laws of physics are on our side here. A small speaker close to us can be much louder than a bigger one further away, I suppose in ears are the most extreme version of that but a personal monitor like the B205D does the job nicely too. The trick of doing it without anyone else hearing is to get it as close to your ears as possible. As a bassist you'll usually be at one side so I just put it on the outside pointing straight at my ears. I've used the Behringer, I tried it against the Mackie and there was little difference I found, since then I've moved on to use the TC voicesolo which sounds better and is light enough to clip to your mic stand. Where the Behringer scores though is that the voicesolo is more prone to feedback simply because it has more frequencies than the Behringer. If you play at very high stage levels the Behringer works well. Studiospares do a Behringer clone which is even cheaper, I've not tried it but it is a clone of a clone and may be as similar to the B205 as it is to the Mackie.

[quote name='LukeFRC' timestamp='1481377455' post='3191852'] why don't they put a HPF as standard on bass amps? [/quote] Just about all amps, bass or otherwise, have a low frequency cut off. Within the preamp stages capacitors are often used to link the signal and these act as filters for bass. That's not universal though. Even if it isn't an inherent part of the design putting in an HPF should really be standard and you could always make it switchable. Building it in would cost pence as opposed to an expensive add on. With the bass control at 3 o'clock you could be applying 1/4 to 1/2 bass boost. Assuming you have 12dB of boost available every 3dB of boost will double the power and the speaker excursion so that could be the problem, it is certainly taking the speaker right up to it's limits. As the idiot who did most of the design I worked on the assumption that the fundamental makes up only about 25% of the signal from the bass. I used the only information I had to hand which was from some testing TKS were generous enough to share. It's impossible for any designer to have control over how their design will be used but if 6dB of bass boost (much less than doubling the amount of bass subjectively) was used then that 25% assumption means 100% and I'd have to assume the speaker was working right up against its limits for considerable amounts of time. I've never claimed this as a 350W speaker. Beyma give out the figure of 350W thermal but that involves a test signal which is constant but with bass and treble filtered according to AES specs. I used 300W max in all my calculations. All ported cabs suffer from this problem and all commercial designs could be damaged in this way. I suppose this should be more widely shared on BC. I'll start a new thread next week, not everyone will be interested in the Beyma.

Did it click at all power levels or just at high powers?

There's three things to consider, will you like the sound? it's going to be cleaner than a bass amp, not everyone likes that. will there be enough bass? If the cab is too small or the bass driver limited in excursion it could wimp out at high bass levels. Will it survive the treatment? Related to the above it will depend upon how much bass you call upon it to give. Quality PA units will be fine as the bass drivers will be designed to take the bass. So will any with DSP built in, which will protect the speaker by turning down your peaks for you.

Hi John, I'm confused too. In your original post you said the driver was blown, which i took to mean completely non functional. Blue Aran are saying it is perfectly OK. What was the original fault exactly? If it was making no sound at all was it potentially a wiring fault? maybe even a dodgy speaker lead/plug/socket. If Blue Aran return it and it works than that is a bit strange but you will have a working driver. Their answers to you have been over aggressive/ill informed but I find it hard to believe they would say it is working if it isn't at all.

[quote name='ROConnell' timestamp='1481107570' post='3189700'] As long as you're in a room with decent acoustics and hearing protection I don't see the problem with playing loud, it's amateurish if the whole band thinks turning up will solve everything, but if you're a group who all know where your instrument sits in the frequencies and you e.q right I don't see a problem with turning up and having a blast, if you take the time to set up properly you should be able to hear most clearly. This depends all on the room and what equipment you have available though. [/quote] This is just technically wrong. All hearing protection is frequency dependant, it filters some sounds more than others. Some aren't bad, but the ears work better without them. High sound levels cause changes in our middle ear which reduce the energy passing to the inner ear to avoid permanent damage. That means you lose a lot of detail at high sound levels. You might get by at rehearsals with ear protection or be able to cope with high levels but you simply won't hear as well as you would at lower levels.

What colour is the lacquer? I have a Japanese Thunderbird that had four nasty chips. I'd tried nail varnish on an earlier bass but ended up using superglue which is slightly harder. Both work well but you can build the super glue up more quickly. To match the colour I used spirit based felt tip pens blending the colours until it was matching in colour slightly darker than the surrounding lacquer. Build the superglue up in layers until it is slightly higher than the surrounding lacquer. I masked off with sellotape so the extra was sellotape thickness. I then smoothed back the imperfections with a razor blade again using sellotape on the blade to avoid scratching the surrounding good finish, then used wet and dry glued to a flat piece of wood reducing the grade from 300 down to 2000 gradually before polishing with some pro car cutting compound a mate had handy. Slightly finer than T-cut. I cant see the joins though I didn't quite get a perfect colour match. Stewmac have a video on you tube showing how to do it.

[quote name='bigd1' timestamp='1480934123' post='3188089'] Fantastic playing if that is your thing, although a little dated. I may be wrong but, isn't Moonlight Sonata about the night, quite time of the day, a time to relax. This version seems a little heavy for my idea of a "Sonata" but that is just me. [/quote] The title Moonlight Sonata wasn't Beethoven's. I once read that is was written because he had an unrequited crush on one of his pupils, to whom it is dedicated. He wasn't commissioned to write it either which is interesting. It has a terrible beauty to me moving on to a rather disturbed and agitated passion, terribly sad and shading into madness. He broke the rules of the classical sonata in writing it that way with the build up towards the end. I'm not sure I'd ever listen to the guitarist playing it again, just pointing out the virtuosity in one of her party pieces.

Hi John, I need to get off and do some work so I'll revisit this later, there's a lot of information here. It looks like your SM212 is still working, so that is good. If that is the case then Blue Aran are right, it isn't worth cutting it open. I'd thought it had stopped working. All the guff about winISD is disappointing. I've seen the same nonsense when Skidder blew his Eminence 3015 Kappalite a few years back. Win ISD just uses Small's equations to describe the cone movements, they can't seriously be arguing that the science is all wrong. The stuff about not being suitable for bass but for PA is also nonsense. What do they think goes through a PA? Clearly they are denying the possibility of using a bass through PA or the existence of bass in recorded music! They are also wrong about the SM212, it is a general purpose driver, Beyma also make the SM112 which is the dedicated PA bass driver. In their English language material they do not talk much about applications and neither critically do Blue Aran. In any case the physics don't lie. They do have a case however about using a bass without a HPF. It's something we have mentioned and true of most commercial units too, in fact it's an issue with all ported cabs and not much discussed. At 40Hz and 300W your cab will not exceed 13.5 mm excursion. At 30Hz and 300/w it will, the speaker isn't indestructible. In any case you shouldn't use the speaker beyond xmax for extended periods and the 13.5mm figure really is an absolute limit. The 25% figure comes from TKS I think and is a good rule of thumb, it doesn't mean you personally use your bass in exactly that way. I'm concerned about Blue Aran's attitude, which may be down to one over zealous employee of course. I think they are trying to browbeat you, and not engaging helpfully, and this is the second time I have seen this. You may well have been using the speaker outside of the parameters of safe operation, we may never know exactly. They may have good grounds for saying that it isn't their responsibility but some of their assertions are untrue and their tone is certainly aggressive and unhelpful. Last time they came on here and did engage a little. It would be useful to know if they are a company with the highest standards we can recommend. I need to go back and look at all of your details. I feel a little responsible for this and if necessary I might need to tweak the design or add some more advice to stop it happening to anyone else.

It's hard to say without more information. It squeals when turned up. Does it do this when there is no signal which would indicate damage to the amp inside, or when you are playing music(not bass) through it. Does it play music when you have it turned down but distorts when you turn up? That would indicate the amp is probably working OK but something mechanical has gone wrong with the speaker.

I share your position at the bottom of a big scary mountain that needs climbing, this is a thread I'm going to follow. Just a little personal insight which is going to make the mountain twice as high, it isn't all about notes, have a look at this and see what you think. I'll never look down my nose at Britney and Pitbull again https://www.youtube.com/watch?v=CtZ74JdxCt0

I was aware of that as I was writing. Then I thought that actually reading is the ultimate skill that makes it possible to unlock a lot of 'theory'. I don't think you can really separate a good grasp of theory from reading I gather little bits of theory when I can, it all comes in useful but I still feel like a blind man. For example I've only recently started looking at the theory behind rhythm. As a bass player the little dotted squiggles, the timing of the notes and the bar lines should have been what I looked at, not being so dazzled by the notes alone. I've been looking at the letters not the words. How the hell do I get better without a proper grasp of what note length really is, and how do I do that efficiently without being able to read and write? As a drummer you must be smiling now.