stevie

An eight-inch bass speaker is something of an oddity. There are a few around but I doubt if it would cost you much more to get an original Ashdown replacement, as Ashdown's spares prices are not particularly outrageous. You will slash its resale value if you put just one non-standard speaker in there. You could also end up with something that doesn't sound very good.

[quote name='JTUK' post='760635' date='Mar 1 2010, 12:34 PM']I think you'll be hitting £200 quite easily on materials and that is without what charge you put on your time, to end up with, a box that will have little resale value and a chance that it will sound decent. As an exercise and a project, then go for it, but personally I wouldn't bother.[/quote] On the other hand, £200 spent on materials could get you a cab that will perform as well as, if not better than, £500 or £600 shop-bought cabs. You're not going to get your money back, that's true, but neither are going to take a huge depreciation hit. It all depends on whether you want to put a value on your leisure time. Understandably, most people prefer to buy something ready made.

[quote name='Mr.T' post='760509' date='Mar 1 2010, 10:45 AM']Not wishing to hi-jack this thread, but..... How did you work out the port sizes? I am asking this as someone who doesn't know the difference between a cab tuned to 40hz or 50hz. [/quote] First, you have to decide what size of port to use. Choosing a port that's too small will result in 'chuffing', compression and distortion. Choosing one that's too big will result in an excessively long port (or too high a tuning frequency) and resonances within the port itself. For this box, I decided on two 3" ports (which I happened to have already). Sizing a port can be a bit of a juggling act with a compact, high powered speaker and flared ports can help reduce the problems of chuffing and compression. Tuning a bass guitar cab is not like tuning a hi-fi speaker; it's largely a matter of ensuring that the driver doesn't run out of excursion when you play the lowest notes. You can model this in most speaker design programs (I don't know about WinSD). The tuning frequency for a 4-string bass usually ends up between 45 and 50 Hz. If you tune to 45 Hz, you will generally be pretty close. In this case, the cabinet size was a given, as were the parameters of the drivers. As I had already figured out that two 3" ports would be acceptable, all I had to do was to work out the length of the ports in my modeling software.

You could also consider the option of taking an existing cab and pimping it. You can upgrade just about any commercial cab by fitting better drivers, bracing it, fitting damping, Speakons, etc. It saves you all the hassle of building a cab and sourcing the bits. I did it with this Laney 2 x 10, bought on Basschat, which I have fitted out with a pair of second-hand Volt drivers. I had to enlarge the holes for the drivers, brace it and fit a couple of rear ports. Despite its compact size, I would expect it to spank most 2 x 10s on the market.

[quote name='waynepunkdude' post='760130' date='Feb 28 2010, 08:41 PM']The speakers will be these. [url="http://www.lean-business.co.uk/eshop/celestion-bn10300s-4ohm-neo-magnet-bass-guitar-speaker-10-p-327.html"]http://www.lean-business.co.uk/eshop/celes...r-10-p-327.html[/url][/quote] It's been mentioned quite a few times on here that the Celestion Orange series is not very good because of (excursion-) limited output. Unless you are looking for an overdriven guitar type sound (which you might be), I'd avoid them. You really need to define your design objectives before you can do anything. For example, do you want a lightweight cab, do you want a compact cab, do you want a state-of-the-art cab, do you want deep bass, do you want something cheap, etc., etc. When you build your own cabs, almost anything is possible. The Greenboy designs are fine, but I don't think they don't include a 2x10. As far as tools are concerned, the minimum you will need is a jigsaw, power drill and a screwdriver - assuming your wood supplier will cut the panels to size for you. A router, clamps, set square and other stuff are all useful if you have them, but probably not necessary for a one-off.

[quote name='Hamster' post='759026' date='Feb 27 2010, 12:31 PM']Having heard the Midget on stage, they are very impressive and made of helium and hummingbird feathers [url="http://barefacedbass.com/index.php?page=midget"]http://barefacedbass.com/index.php?page=midget[/url][/quote] It may be slightly too large or too expensive for the OP's needs, but the beauty of the Midget is that it's small enough to be unobtrusive at home, but powerful enough to work well in many live situations.

[quote name='Dom in Somerset' post='757907' date='Feb 26 2010, 09:43 AM']Do we have a date yet?[/quote] As it's highly unlikely that John will want to organize a bash in Exeter or Bristol, I wonder how many voting for those locations are prepared to do all the organising? Perhaps now would be a good time to volunteer.

[quote name='steve-soar' post='757763' date='Feb 26 2010, 12:34 AM']"HiFi"bass tone. Shudder. [/quote] I'm not sure what a 'hi-fi' P-bass tone is. Anyone care to enlighten me? Does it just mean clean, full range, or what?

Bought a beat-up old bass case from Dave to use for shipping a bass. Just as described (crap ) and just the job! Clear communication and a really easy bloke to deal with. Thanks, Dave.

[quote name='Phil Starr' post='753503' date='Feb 22 2010, 09:16 AM']Regarding Xmax.[/quote] Phil, Eminence explain how they measure xmax somewhere on their website. It's not simple voice coil overhang. It's true they used to use the same method as Celestion but they don't any more. Have a look at this Beyma speaker here: [url="http://profesional.beyma.com/ingles/pdf/12P80Nd.pdf"]http://profesional.beyma.com/ingles/pdf/12P80Nd.pdf[/url] It has a voice coil overhang exactly the same as the Celestion, 4mm. Yet the stated xmax is 7.5mm - nearly twice as much. If you are going to compare xmax, you have to compare the same thing.

[quote name='Muthawhat' post='754759' date='Feb 23 2010, 10:11 AM']ahh hello local chaps! Dont suppose anybody knows of any heads and cabs for sale? or a 4 string?[/quote] [url="http://basschat.co.uk/index.php?showtopic=78245"]http://basschat.co.uk/index.php?showtopic=78245[/url] But you'd better be quick. Also, have you seen the South West Bassbash thread?

Hello from just down the road in Dorchester.

[quote name='karlthebassist' post='752069' date='Feb 20 2010, 07:09 PM']I told him about this cab and I'm going to send the actual driver off to him once I get my other cab back for his tech chap to look at. He said that he has only ever had a couple of problems with Aguilar gear in all the time he's dealt them, and for me to have two faults is a bit too much to be a coincidence - to which I agree with him fully. As his expert said, the first cab was definately a fault, but this one... dunno. I'm going to get my amp checked by a pro to make sure its ok.[/quote] But the first faulty speaker had a manufacturing fault - you didn't cause it. It's irrelevant to the current problem and certainly doesn't make it any more likely that you damaged the second one, which is what your dealer seems to be saying. I wouldn't buy that. If you haven't overdriven the speaker (which seems to be the case from what you have said), you should get a warranty replacement. Chin up!

[quote name='RIM Basses' post='751447' date='Feb 19 2010, 11:02 PM']Cheers for that Steve, Ok so how large is a 50 Litre Cab. Im gonna do the whole cab out of 18mm Marine Birch ply.[/quote] The formula for volume in litres is Length x Width x Depth in centimetres, divided by 1000. Internal dimensions, of course. So, you could go for 42 height (dictated by the diameter of the speaker) x 47 wide x 28 deep. That gives you 55 litres and allows a bit for bracing and the driver volume. Adjust the sizes to whatever you prefer. Just avoid making any of the dimensions the same or simple multiples of each other (i.e. 30 and 20) to spread internal standing waves. The worst shape for a speaker cab is a cube. With 18mm ply you probably won't need to brace it, but I'd consider putting two 2-inch deep, side-to-side braces across the longest length of the back panel. The stiffer the back panel, you more 'slam' you get, in my experience.

The prognosis is starting to look a lot better. You need to do one more thing to rule out a damaged coil. (I'm glad you have a multimeter - that certainly simplifies things). It's possible that the coil former has expanded slightly due to excessive heat but that there is still enough gap to allow the coil freedom of movement when it is cold. The scraping and consequent distortion will therefore happen only when the coil is warm. So, allow the speaker to cool down for half a day, then try it. If the distortion starts straight away, your coil is OK. The reason you need to be absolutely sure that the coil has not been fried is that virtually any other fault is covered by warranty. I suspect what has happend is that the glue between the surround and the chassis has failed at the point where you are pressing. The surround is flapping against the chassis here and producing a nasty noise. Whatever is is, your best bet is to make a warranty claim because your speaker almost certainly has a manufacturing defect. It's not quite clear to me whether you bought this cab new, but remember that Eminence in the US offers a 7-year warranty against manufacturing defects. So you should be covered. Let us know how you get on.

I hate to say this, but it does sound like a fried coil. The voice coil former has probably expanded because of excess heat and is rubbing against the centre pole. What happens when you press on the surround is that you push the cone slightly to the side, which twists the voice coil, pulls the bulge away from the centre pole and stops the rubbing. Try pushing the cone in and out by exerting even pressure all round on the cone (i.e. not twisting it at all) to mimic the normal in-out movement of the cone. Listen for scraping behind the centre dome. If you do hear scraping, then the voice coil is on its way out. You have to do this very carefully because you can cause the voice coil to scrape if you twist the cone even slightly. I hope that I'm wrong.

[quote name='velvetkevorkian' post='750719' date='Feb 19 2010, 11:51 AM']...or their wallets... [/quote] Absolutely! [url="http://www.pnas.org/content/105/3/1050.abstract"]http://www.pnas.org/content/105/3/1050.abstract[/url] The authors of this scientific paper (N.B. not an article by a pimply-faced audio journalist) took 20 volunteers and gave them wine without telling them whether the wine they were tasting cost £5 or £100 or something in between. When they were told they were drinking the £100 wine, the fMRI recorded higher levels of activity in the part of the brain associated with pleasure. It didn't make any difference what wine they drank. If they thought they were drinking an expensive wine, the brain automatically registered greater pleasure. I have seen previous scientific research which demonstrated that the power of aspirin to relieve pain increases according to the lavishness of the aspirin pack. That was based on subjective statements, and whilst it was properly conducted and therefore authoritative, this research was based on actual brain scans. The application of this paper to cables, pickups, strings, exotic woods, limited signed editions, and so on, is obvious. The human brain will gain more pleasure from expensive products even when the only difference between them and other products is that they cost a lot more.

This almost disappeared off the radar. Here's the model for the 50-litre sealed cab I recommend you try for the Celestion. Graph 1 shows the response at 1 watt. The blue curve is the Celestion in a 50-litre sealed cab. For comparison, I've included (in green) an Eminence 3015 in a 70-litre reflex cab. There's not really a huge difference between the two. Graph 2 shows how these two cabs compare with a theoretical 400 watts power input. Because it is reflex loaded, the Eminence cab can handle the full 400 watts and will therefore go louder. The Celestion, on the other hand, will only take 200 watts - although adding a second Celestion 15 will make up for the difference. To improve the power handling of the Celestion, you could reflex load it in a larger cab but this will almost certainly produce a boomy and ill-defined bass sound. If you have the choice, I'd suggest you use 15mm birch plywood for this, perhaps with an 18mm front baffle.

Very good, MIJ! Let me just say that sometimes a bit of bah humbug is sorely needed around here! Oh dear, you seem to have dropped your rattle. Allow me