stevie

[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.

[quote name='five-string.co.uk' post='618652' date='Oct 6 2009, 03:14 PM']Welcom on board fellow Benz owner [/quote] ...... and from a fellow Dorset resident. Not that you'd know, but there are a few of us on here. Stevie

The fact that their website doesn't include an address or phone number doesn't exactly fill you with confidence, does it?

[quote name='Skywalker83' post='612865' date='Sep 30 2009, 11:53 AM']Last night i won a Westfield P/J P-bass on the bay complete with EMG pickups![/quote] Don't you love the way eBay has us all believing we *win* things. Excuse me while I pop down to Tesco to win the shopping. I'll win some petrol on the way back.

Bought some lightweight tuners from Michael. Impeccable service. You can't go wrong.

[quote name='matski' post='608434' date='Sep 25 2009, 10:13 AM']Anyone out there an expert on the Fender JV Squiers? I recently retrieved an old one I had lent to a friend about 20 years ago - it is one of the Precision models with the big Fender logo and the smaller Squier Series logo - it was sunburst with gold anodized scratchplate, so it was the '57 vintage model, right?[/quote] The original 57s had an anodized scratchplate but the JV Precisions didn't.

Don't be tempted to buy Bass Guitar for Dummies. It's utter tripe.

I didn't find the Superman one, but I did find this: [url="http://www.thebassclef.co.nr/"]http://www.thebassclef.co.nr/[/url]

[quote name='krispn' post='606656' date='Sep 23 2009, 01:51 PM']someone has a really cool Superman avatar with the bass clef repalcing the superman 'S'[/quote] It's always nice to be noticed. Yes, the avatar is available as a t-shirt, but I'm blowed if I can remember where I nicked it from. Doesn't Google have some kind of search facility for images? I'll have a quick look to see if I can find it for you.

[quote name='XB26354' post='605574' date='Sep 22 2009, 01:50 PM']With regard to reading up the neck, do you mean changing position or just playing a piece higher up the neck? if you mean changing position then there is an old double bass exercise I used to use: Fret the A string at the first fret with the index finger. Without looking at the fingerboard, shift and fret at the second fret. Go back to the first fret. Repeat slowly over and over. Then go 1st-3rd fret, again without looking. Continue up until you are shifting a whole octave on one string. It can be done and if practiced regularly you'll never have trouble with position shifts.[/quote] I don't really have a problem shifting without looking at the fingerboard, although I like your exercise and will definitely use it. I'm finding it quite difficult to achieve the kind of reading speed in the 5th and 7th positions that I've developed in the first position - accidentals in particular slow me right down. I'm much more comfortable playing lower down and just jumping up to reach the higher notes on the G string, which is clearly not the way to do it. [quote name='XB26354' post='605574' date='Sep 22 2009, 01:50 PM']As for playing higher up the neck, I recommend taking and bass lines or stuff you work on that mostly covers the A, D and G strings and shift it to cover the E, A and D. Also try learning scales with 4 notes per string, as per the example using C major below: 8th fret E-string: C-D-E-F 10th fret A-string: G-A-B-C 12th fret D-string: D-E-F-G 14th fret G-string: A-B-C-D And back down. This is what I call the "crab-walk" as your hand is almost constantly shifting. It is surprisingly challenging as it forces you to look at information horizontally rather than vertically.[/quote] I'll give that a go, too. Thanks, Mat.

I like this: "If you are given a line of 16th notes that are not playable at sight, play the first one, use muted notes for the middle ones, and play any accented notes and the last one. Yes, it's cheating and ideally you should play them all, but this really works on gigs if something terrifying is put in front of you :-)" Any tips on sightreading up the neck? I'm really struggling with this. Are there any shortcuts I'm missing?

[quote name='pal1972' post='604890' date='Sep 21 2009, 07:40 PM']As the RCL drivers are primarily PA drivers do they work best in a sealed cab??? if so is it OK to block up the rear port holes on my cab???[/quote] No, that would be a retrograde step. They'll handle less power that way.

[quote name='bassmansky' post='604747' date='Sep 21 2009, 05:19 PM']RCL drivers are one of the best you can buy imo.i would think twice before changing that.[/quote] I wonder if you're maybe thinking of RCF.

Bought a speaker cab from Jay recently. He went that extra mile and I'd be happy to deal with him again.

[quote name='Delberthot' post='601440' date='Sep 17 2009, 04:47 PM']I've thought about something that I'll need to check as well - I've only ever fitted drivers to front loaded cabs before - never where they mount from behind the baffle - do I need to do anything special other than offer them onto the bolts and tighten them up?[/quote] You'll be very lucky if the bolts are in the same place as the bolt holes on your new speaker but you can always check the manufacturer's specs before laying down your money. I think a bit of jiggery pokery may well be called for.