stevie

Bought a book from Bluesparky, which was nicely packed and sent recorded delivery. Just as good as Amazon, IMO :-).

[quote name='lukertweek' post='626831' date='Oct 15 2009, 12:25 PM']Could you recommend any specific ceramic makes/models?[/quote] That's virtually an impossible task because there are so many, especially if you go the eBay route. Here's some tips on what to look for in the specifications. A too powerful magnet (low Qts under .25) means the driver is designed for horn loading and won't produce much bass in a reflex box. Too small a magnet (high Qts of .5 and over) means a cheap driver built down to a price that will sound boomy. And finally, a short coil (xmax of 3mm or under) means the cone won't be able to move very far before it starts distorting. Don't be too concerned about the maximum power rating. Look for a resonant frequency of between 38 and 48Hz. A cast chassis is a good sign. You could post a shortlist if you like, or ask about a specific driver.

Your box is around 110 litres internal volume. If the port is somewhere between 100 and 170mm long it will be in the ballpark. A neo magnet speaker is a good choice, but if you don't mind the extra weight, a ceramic magnet speaker will save you some money and also open up the second hand market to you.

[quote name='7string' post='624604' date='Oct 13 2009, 12:01 AM']The first guy has a video where he plays all the instruments and creates a cover of YYZ. One of the most impressive things I've seen on YouTube.[/quote] It's here: [url="http://www.youtube.com/user/RushZappa2112#p/a/u/0/fZmP4FngzHA"]http://www.youtube.com/user/RushZappa2112#...u/0/fZmP4FngzHA[/url] I'd say impressive is an understatement.

[quote name='wateroftyne' post='625007' date='Oct 13 2009, 02:24 PM']...and look at how many of them have survived intact. That, along with the rose-tinted rock'n'roll dream, is what fuels the collectability - and that's not going to change any time soon...[/quote] Dream on WoT.... you're an incurable romantic. What fuels their collectability is the expectation that they will increase in value - like stocks, shares, property and Chippendale furniture.

[quote name='wateroftyne' post='622947' date='Oct 11 2009, 10:50 AM']It always puzzles me when threads like this appear. Paying silly money for old collectable things, musical or not, is a practice that has been going on forever.[/quote] Coming a bit late to this thread.... What is different now, though, is what has become collectible. It used to be that exclusivity and quality counted for something. And age - something has to be at least 100 years old to be considered antique. Sixties Fenders were (relatively) cheap, factory-built, mass-produced instruments that sold in their thousands and could be bought by any pimply teenager who could get his dad to OK the hire purchase form. They may have had plenty of competitive advantages, but there was never anything exclusive about them. Jimi's Strat might be an exception, but they really should be about as collectible as a Mk II Cortina. There is a whiff of the Emperor's New Clothes about this vintage collection nonsense, which could make it a bubble ready to burst. I wouldn't bet my pension on one, that's for sure. But just look what's happened to pensions of late.

[quote name='alexclaber' post='624830' date='Oct 13 2009, 11:36 AM']Does anyone think it's worth having my Barefaced cabs reviewed by BGM? I've contacted them a few times of late but they appear to be ignoring me...[/quote] A positive review is just about the best form of sales promotion you can get, but because of limited space, magazines will always give precedence to their advertisers. If you were an advertiser they wouldn't ignore you. These are the sad facts of commercial life, I'm afraid. Which doesn't mean you shouldn't keep trying, of course. Come back gentleman journalist Gary Cooper and Music UK, I say.

[quote name='Le Chat Noir' post='624754' date='Oct 13 2009, 10:12 AM']I guess asking him to turn down might be my firstp ort of call!! [/quote] That would work, yes - and could save you all from suffering hearing loss in later life.

This is a difficult one. What you are describing is the 10-inch drivers exceeding their excursion limits. You must be in a very loud band! There are a limited number of options to remedy this, but first of all let the driver run in. Check also that the drivers are properly sealed and that there are no leaks. Check for a faulty driver - in other words, does the 'farting out' come from all drivers at the same time? Also, make sure that it's not your amp that's running out of steam. Your 15-inch box will handle more power than the 4x10, but if the amp is giving out, you should hear similar symptoms through the 15 as well. Sorry if this is all a bit obvious: I'm just trying to cover all bases. If all of this fails, these are your options. Perhaps somebody else will add to this. 1. Use your tone controls to reduce the amount of 40 - 60Hz going into the speakers. This is definitely your cheapest option if you can live with it. 2. Replace the 10-inch drivers with better ones. This is your most expensive route. If you can afford it, you might consider it. 3. Buy a decent quality power amp that works in bridged mode into 8 ohms - 250 to 600 watts - and power it from the preamp-out on your bass amp. Balance the power going into each cab using the balance control on the power amp. This will allow you to increase the power to the 15 and reduce it to the 4x10. There were some suitable power amps on here not long ago for well under £100. Damping the inside of the cabs is certainly worth the effort. It will clean up your sound, although it won't stop the distortion you are experiencing. There was a thread on this here just recently. I use BAF wadding, 2-inches thick (don't bother with the 1-inch stuff) stapled to the cab with a staple gun. The trick is to stop the wadding moving without compressing it too much. You could probably also stick it to the cab using something like Copydex. I''m sure that would work OK, but I've never done it. Good luck.

[quote name='Le Chat Noir' post='624089' date='Oct 12 2009, 03:48 PM']This was my thinking too. To be honest I've never been 100% happy with the ABM cabs, hence the driver swap in the first place! I find them a little woolly. I imagine making some enclosures thast were designed for these specific units might yield better results and allow the speakers to realise their full potential.[/quote] I wonder if maybe you've been swayed by all the talk of 'wooly Ashdown' on here. Devon's not a million miles from South Wales. There will be some Fitzmaurice cabs at next month's South Wales Bass Bash to try out. Could be worth the trip.

[quote name='alexclaber' post='624097' date='Oct 12 2009, 03:50 PM']Did you add damping to the cabs when you swapped the speakers? I know many Ashdown cabs are a little short on that front![/quote] You beat me to the punch on that one.

[quote name='Stylon Pilson' post='624066' date='Oct 12 2009, 03:27 PM']Do you think so? I would expect him to get much better results if he transplanted the speakers into a cabinet that was designed specifically for them.[/quote] That's certainly the case for hi-fi speakers and full-range PA speakers, but it's less so for bass guitar cabs. The enclosure design of a 15" or 4x10" bass guitar cab is something of a standard commodity nowadays: size 85 to 115 litres, tuned between 40 and 45 Hz. There are dozens of 15" speakers that will work to that spec and plenty of bass guitar 10s that are interchangeable. The ABM 15 Compact is 90 litres tuned to 45 Hz (same as the Trace 1153). Funnily enough, the Eminence 3015LF is better suited to the cab than the speaker Ashdown have fitted. I've measured the Ashdown driver, and it really should be in a bigger box. The Ashdown ABM cabinets are beautifully made in 3/4" birch ply (I've got one). The 3015LF is the driver fitted to the excellent Bareface Big One. The Deltalight 10s are very uncoloured in the midrange and fine in a 4 x 10 combination. I'd expect it to be really, really good.

[quote name='Le Chat Noir' post='622530' date='Oct 10 2009, 05:20 PM']I have a KappaLite 3015LF and four Deltalite II 2510 which I currently have installed in some Ashdown ABM cabs, but I'm thinking of selling my Ashdown rig and might keep the speakers.[/quote] You will find it very difficult to improve on the system you have now: it's close to state-of-the-art IMO. Before making any changes, be sure to audition first. If you're unhappy with your sound, it's unlikely that your speakers are the cause.

In other words, a free lunch there is no such thing as!

[quote name='alexclaber' post='623937' date='Oct 12 2009, 01:28 PM']Interesting. If the increase in compliance was due to a lowering of the speed of sound one would expect this to be consistent with larger boxes - so does this suggest that a larger box is inherently more isothermal due to the greater heat capacity of the air within it and the greater radiating area of the enclosure? I presume overstuffing is counterproductive because the increase in compliance due to heat absorbtion is offset by the decrease in actual net volume. Alex[/quote] I've never seen an explanation for it, Alex, and I doubt I'd understand it if I did. But his big enclosure was 5 cubic feet, which is not a very practical size. Did you have a look at the Kantor link? (oops, no, this was in the Nousaine piece) There was quite a useful tip for optimizing midrange cabinet stuffing by measuring the impedance, I thought.

Interesting, but without any citation it’s a bit difficult to comment. Thiele and Small’s work has been constantly refined over the years and the effects described could easily be classed as ‘system losses’ in TS theory, which may be what Alex was referring to earlier. [url="http://web.archive.org/web/20041027051204/http://www.integracaraudio.com/caraudio/resources/fiberfill/"]http://web.archive.org/web/20041027051204/...rces/fiberfill/[/url] is a much-quoted experiment by Tom Nousaine which demonstrates that stuffing a sealed box can lower Fb by at least 10 percent. He also, interestingly, shows that stuffing is less effective with larger boxes and that overfilling is counterproductive. Countless speaker engineers have observed the same (Ken Kantor here: [url="http://www.lungster.com/l/speakers/BassListArchive.shtml)"]http://www.lungster.com/l/speakers/BassListArchive.shtml)[/url]. As resonant frequency is a function of mass and compliance and stuffing does not change the mass of the speaker, a drop in resonant frequency means an increase in compliance. This is the proof of Small’s statement as I see it. To disprove it would require some other explanation or a demonstration that the drop in resonant frequency does not in fact occur. I don’t think Small went any further than to observe this increased compliance and so I do not see how his theory has been ‘debunked’. Is there any accessible published data on the AES position?

This is an exceptionally informative review and much appreciated.

[quote name='Bill Fitzmaurice' post='621842' date='Oct 9 2009, 05:28 PM']One could make that case, but the more likely explanation is that they don't want to add to the build cost of the cab by properly lining it. They'd feel quite safe in so doing based on the facts that most users aren't aware that the cab should be lined, and those who do aren't likely to examine the inside of the cab before buying one.[/quote] I feel compelled to agree with Bill here.

[quote name='Bill Fitzmaurice' post='621782' date='Oct 9 2009, 04:41 PM']Mr. Small disagreed in 1972. In the intervening three plus decades the above explanation of how stuffing works has been found to be incorrect. As recently as three years ago the esteemed Vance Dickason's 'Loudspeaker Design Cookbook' still espoused this debunked theory, but in the latest edition he too has come on board with what is now recognized by the AES as to the true function of stuffing. How stuffing affects the cabinet Q and impedance can be clearly and easily seen with current loudspeaker modeling software; the accuracy of the software has been confirmed with actual measured results.[/quote] His explanation about how stuffing works may be incorrect (although I think if you slag off Richard Small the least you could do is provide some supporting references) but the practical consequences of stuffing a sealed box are the same – you increase the effective box size! Call it increasing the compliance of the enclosure or lowering the system Q - these are both things that happen when you increase the size of the box.

[quote name='Bill Fitzmaurice' post='621735' date='Oct 9 2009, 03:38 PM']No. Packing a sealed cab will lower the box Q to tame a midbass peak. Contrary to popular belief it will not give the same result as a larger box.[/quote] Mr Small ([i]the[/i] Mr Small) disagrees. In fact, he disagreed in 1972 in his AES paper called "Closed-Box Loudspeaker Systems" when he said: "Many closed boxes contain filling material which helps to damp standing waves within the enclosure at frequencies in the upper piston range and higher. If the filling material is chosen for low density but high specific heat, the air compression inside the enclosure tends to be partly or completely altered from adiabatic to isothermal. This increases the effective compliance of the enclosure, which is equivalent to increasing the size of the unfilled enclosure. The maximum theoretical increase in compliance is 40%, but using practical materials the actual increase is probably never more than about 25%. An ancillary effect is an increase in the total moving mass of the system. Depending on the initial diaphragm mass and the conditions of filling, the mass increase may vary from negligible proportions to as much as 20%" It doesn't apply to a ported cab, though.

[quote name='alexclaber' post='621646' date='Oct 9 2009, 02:22 PM']Get a roll of loft insulation and use what's left over to keep your house warm![/quote] Fibreglass works really well. I'm not sure of the health issues in a ported cab, although I have a JBL cab here with fibreglass in and I've not noticed any problems. You can get BAF wadding and acoustic foam from specialist suppliers like Wilmslow Audio or on eBay. I've found that foam at the the long end and BAF along the side walls works best, as foam can kill the bass if you're not careful. I've also heard of people getting good results from furniture stuffing, although I'm not sure exactly what they used. Make sure to keep the wadding well away (6-inches, say) from the ports. This is well worth doing and you'll hear the difference.

[quote name='Bill Fitzmaurice' post='621073' date='Oct 8 2009, 10:08 PM']Because it's cheaper.[/quote] That's a very simplistic view of the situation. Moulded plastic cabinets are both lighter and cheaper than wooden cabinets, for example. [quote name='Bill Fitzmaurice' post='621073' date='Oct 8 2009, 10:08 PM']Many cab manufacturers make a big deal about using 3/4" plywood, as if that's a good thing. It's not. Manufacturers use 3/4-inch plywood because it will give an adequate result with minimal bracing and can be assembled by unskilled minimum wage help in less than two hours from start to finish. A properly braced cab made from 1/2-inch plywood will be significantly lighter than a cab made from 3/4", yet it will have the rigidity of a cab made from 1-inch.[/quote] Professional cab builders have been using 3/4-inch birch ply for decades and have yet to find anything better. Talk to one! If you specify the very best material for your bass cabinet, you will get 3/4-inch birch plywood. It offers an ideal compromise between weight and acoustic performance. Some manufacturers choose not to brace their cabinets, although the better ones do. However, if you build a cabinet out of 1/2-inch ply you have no choice – above a certain size, you have to brace it or it will just shake itself to bits. A properly braced cabinet made of 3/4” ply will always outperform a properly braced cabinet made of 1/2-inch ply. Not only will it be stiffer, but the 3/4-inch plywood cabinet will be less resonant because it has higher internal damping. [quote name='Bill Fitzmaurice' post='621073' date='Oct 8 2009, 10:08 PM']But build time will be roughly doubled, as will the number of parts in inventory, so with the overwhelming majority of manufacturers that's not how it's done.[/quote] Two hours to assemble a cabinet and two hours to put bracing in? You're just pulling numbers out of a hat, aren't you Bill? By that reckoning, each worker would produce two cabs a day! Bracing won’t double the parts in the inventory either, because they’re made from the same wood as the cabinet.

The Trace cabs, as far as I remember, Mr Foxen (sorry to be so formal ), use several interlocking circular braces - not just bits of sticks. They're not expensive either.

[quote name='Mr. Foxen' post='620919' date='Oct 8 2009, 07:42 PM']There is glueing in sticks and there is proper pre-stressing and tensioning. Stuff I mostly read about in small aircraft making books, light and stiff is a very important thing in aircraft.[/quote] There are many lessons that could be learned from aircraft building but most of them come at a price. Let's face it, even plywood is an exotic material for most cab manufacturers. What's important in a speaker cab is stiffness and damping. Light is great but when you make a cabinet lighter, you risk compromising those qualities. And by the way, in answer to fenderiko's question, there are already quite a few companies producing lightweight bass cabs. We've had lightweight PA cabs for decades, but making a half-decent lightweight bass cab is not quite so easy.

[quote name='Mr. Foxen' post='620822' date='Oct 8 2009, 06:07 PM']Labour intensive and don't lend themselves to mass manufacture.[/quote] I'm sure that's what the boutique builders of lightweight cabs would like you to believe, but putting a bit of bracing inside a cab is not very labour intensive at all. Have you seen the inside of the lightweight Trace cabs? They are braced like nobody's business.