stevie

[quote name='voxpop' timestamp='1353345096' post='1873998'] Would I be better off perminatly blocking off the cab ports / holes and making a sealed cab with the celestion driver. [/quote] As Lawrence says, you'll reduce power handling a bit, but that Celestion driver has a very high Qts which is more suited to a sealed system. The undersized magnet syndrome strikes again.

[quote name='bremen' timestamp='1353344945' post='1873992'] My preference is also flat, but humps and bumps in the right places can add to the character of a sound in a positive way, wouldn't you agree? [/quote] If you're lucky, yes. The problem is that the frequencies with humps and bumps are often accompanied by other problems that you don't want (like resonances, distortion, suckouts). Better to have a clean, smooth (though not necessarily flat) frequency response that lets your 'tone' shine through. Then dial in your 'character' before it gets to the speaker. I know others take a different approach, and that's fine, but I don't want my speakers to add colour.

Massive humps and bumps have no place in any speaker system. They are usually caused by bad design or skimping on cost. The 100Hz bump that is common in bass guitar cabs is usually caused by using an undersized magnet to save money.

Back home now. The family had lunch at the pub (good prices) and then left to have a wander around Sherborne. I had a whale of a time trying out all the lovely gear and was particularly impressed by a great-sounding Sandberg that I'll never be able to afford, but never mind. A big thanks to John (oldslapper) and Yorks5stringer for all their good work in organizing everything. I'll try to bring an amp and a cab next year!

I'm hoping to see you all there. I'll be bringing a heavily modified Yamaha 1100S. Anyone interested in listening to Duncan and Delano pickups or TI Flats can help themselves.

You then end up with a cab made out of 6mm balsa wood. The sensible thing is to go for the most effective solution for you.

Given the choice, a well-braced 18mm cab is better than a well-braced 12mm cab, which is better than a well-braced 6mm cab. You really have to compare like with like. Why compromise if you don't have to? I'm not saying a well-braced 12mm cab is necessarily awful, but if I were to build a Fearful for myself, I'd use 18mm birch - that was basically my point earlier.

Thanks for the info. I've decided to stay in the first position after all. Very nice bass sound you have there, Crez.

[quote name='TPJ' timestamp='1349707158' post='1829367'] why? It looks as if the cabs have been designed around strong internal bracing to reduce cab resonance and weight instead of using heavy ply. again, why? This fearful stuff was run through the mill with testing and people experimenting will xovers. It looks as if they arrived at a pretty well suited and varied set of xovers to use. [/quote] Because 18mm ply has proven itself over the years to be the ideal material for bass cabinets. It's a balancing act. Thicker is better, but not that much better. Thinner wood and lightweight woods - even plastic - are OK for midrange, but going down to 12mm ply is a compromise for bass. Plenty of people are prepared to make that compromise because it gives them a lighter cabinet. Which is fair enough if portability is a priority. All cabinets should be properly braced. Testing and experimenting is no substitute for measuring. You have to be able to carry out measurements to design a crossover properly and I don't think anyone did that. Anything else is guesswork.

Would a set of wheels under your cab help?

[quote name='PURPOLARIS' timestamp='1349557346' post='1827814'] Ok wasn't aware of that, I thought you could just slot in drivers that would be suited to the volume of the cab. [/quote] If you use similar drivers to the ones specified, you could, although the driver complement in these is better than 95% of bass cabs on the market. You could fit a cheaper speaker than the Eminence 12/15LF - or a better one - but those Eminence drivers are good value (for neos) and perform well. It's a shame they don't use 3/4" birch ply and that the crossover is a bit of a bodge. IMO of course.

That's a great performance. We're doing it in E flat (or C minor). What position on the neck do you play it in?

I'm currently learning this tune that I'm sure a lot of you guys play already. It is possible to play it at the first position or one string down in the middle of the neck. Both give me wrist ache at the moment (for different reasons). So I'd like to know which position I should be playing it in. The Trammps bassist seems to be playing it in the first position in the video, but that doesn't necessarily mean a lot. Thoughts?

[quote name='davey_one_visits' timestamp='1349348337' post='1824992'] Is anyone aware if such a resource exists? [/quote] Yes, the Major's boot camp. It's very, very good and will cost you nothing, thanks to the Major's generosity to this forum. It beats the pants of the commercial books I have bought on the subject. http://basschat.co.uk/topic/74284-the-majors-bass-boot-camp-session-index-1-36/

[quote name='xgsjx' timestamp='1349442584' post='1826395'] But then Bill's Titan 48 say's otherwise... That's a 1x15 vs a 2x18. [/quote] That drawing doesn't say anything about 4x10s. All it says is how good Bill Fitzmaurice is with a felt pen.

You can't calculate radiating area accurately from the speaker diameter because the surround accounts for a larger proportion of the speaker diameter the smaller you go. PA 4x10s have around 15% more radiating area that 18s - not a huge difference - but in practice have much lower excursion capabilities. An 18" thus has the potential to move a lot more air than 4 x 10s. The fact that most people believe the opposite to be true is down to their respective efficiency in the midrange.

The Marshall 4x12s from the late sixties didn't produce any true bottom.

[quote name='Wiggybass' timestamp='1349438407' post='1826290'] What are the others? Assuming equivalent amplifier power etc.. [/quote] Alex already mentioned excursion, and it is worth adding that the average 18" PA driver has twice the excursion of the average 10" PA driver. But assuming equivalent amplifier power, the reference efficiency of the driver and the size of the cabinet (or the moving mass to air-load mass ratio).

[quote name='Wiggybass' timestamp='1349437150' post='1826262'] Replacing a single 18 with a 4 x10 should make quite a bit more racket because it will shift a lot more air. If we assume that the whole surface of a cone driver is active in terms of direct air displacement (it isn't quite but let's keep this simple), then one 18" driver has a surface area of roughly 176.71". A single 10" has a radiating area of about 78.54" so four of them working together will have 4 x 78.54" = 316.16" bashing the air out. [/quote] Maybe. Maybe not. It depends on several things and radiating area is only part of it.

[quote name='peteb' timestamp='1349295813' post='1824504'] [color=#222222]I switched from using a SWR 4x10 and a 1x18 to using two matching 4x10s after reading something on here (from Alex I think), which I interpreted as speaker cabs with different size speakers will always be slightly out of phase with each other whereas matching cabs will always have the speakers working together i.e. moving together at the same speed.[/color] [color=#222222]This seemed to make sense to me and it did seem to sound better (or at least more efficient) but had I understood the reasoning for doing so correctly??[/color] [/quote] I'm afraid not. The only reason to change your 18 would have been to increase power handling (although even this is a bit moot). Otherwise, a 1 x 18 will work with a 4 x10 as well as another 4 x 10 – in many cases better, in fact, because 18s don't normally have an extended HF response and are thus less likely to cancel the mids/highs coming from your 4 x 10.

Ashdown should be ashamed of themselves for fitting 3-inch ports in this cab. I know it's a budget cab, but there's really no excuse for this level of penny pinching. I'd really like to see some accurate measurements for this cab to confirm or refute whether they have mis-tuned it. Interesting. I've made lots of 15-inch bass cabs and have found 2 x 4-inch ports perfectly adequate. The vent air velocity graph in my design software agrees. Use Roland's method of enlarging the existing holes and fit two ports with a lip. It will look perfectly pro and will perform much better at volume.

[quote name='Phil Starr' timestamp='1348170480' post='1810454'] Aren't the ports on the back of the Mag? If so how worried are you about how they look? You could probably find a chippy to cut the holes for you for a few quid if you are nervous about it. Get hold of the porting first though, I use black soil pipe or drain pipe mostly. [/quote] Yes, the ports are on the back, which means you are cutting through the vinyl and it really needs to be neat. A port with a lip on it gives you some margin for error, and the hole doesn't need to be perfect. Drain pipe is great on the front behind a grille.

Oops, yes, you're right. Those are the ones. I've no idea what happened to my link.