Bill Fitzmaurice

Mixing driver sizes is much like mixing tyre sizes. In some rare instances the vehicle has been specifically designed for it, and the tyres specifically matched to the vehicle, and it works well. But otherwise you may end up driving around in circles.

[quote name='bassjamm' post='214941' date='Jun 8 2008, 10:58 AM']That looks a bit quirky...not sure i'd get taken seriously using one of those on my gigs!!![/quote]Confucius say if being taken seriously depend on how gear look rather than how it sound consider changing occupation from musician to painter.

[quote name='xgsjx' post='212491' date='Jun 4 2008, 09:07 AM']If I built this or bought a PA sub (8ohm) would it work ok with my MB combo & just give more depth to the bass (like car or PA subs do G[/quote] Yes, provided a crossover is used so that the two augment each other rather than detract from each other. The T24 plans include a passive crossover option.

[quote name='Musky' post='210977' date='Jun 2 2008, 05:33 AM']I was considering one of BFM's cabs and was wondering how the bottom end would compare to the 4x12 - I found [url="http://www.aikenamps.com/Marshall4x12response.htm"]this[/url] the other day.[/quote] At 50 Hz the Marshall is 30dB down from average, an Omni 15 is down 3dB. That 27dB differential means that what the O15 will do with one watt input at 50Hz would require 500 watts into the Marshall. But this assumes the Marshall drivers could make use of 500 watts, and being guitar drivers they can't, they're excursion limited to only 5 watts or so at 50 Hz.

[quote name='Adam.M' post='210891' date='Jun 1 2008, 08:25 PM']would the shape of this slanted cab just make it sound terrible?[/quote] Not necessarily, but using a cab that's not specifically designed for bass with drivers that are not properly matched to it would.

[quote name='bass_ferret' post='209704' date='May 30 2008, 10:51 AM']Sorry but you are asking the impossible. Bass gear that can faithfully reproduce a low A is f***ing expensive and human hearing at those frequencies is not very good. There is a very good reason for bottom E being the bottom E and it is because it is usually the lowest note a human voice can reproduce. And the human ear is most sensitive to the frequency range of the human voice.[/quote] The reason for going only to E was that's what double bass did, and the original PBass was intended as a portable alternative to the double bass. Jamerson, and everyone else in those days, seldom ventured below G, because the speakers wouldn't handle it. That's no longer the case, and most well engineered modern cabs can go to A1, but it's the harmonics where the power lies anyway. BTW, the human voice doesn't do 41Hz, and the ear is most sensitive around 300-500 Hz- where the fundamentals of the female voice lie. Ostensibly to best hear the call to dinner across the savannah.

[quote name='clagooey' post='206694' date='May 26 2008, 12:49 PM']... That link looks really interesting. And I'm sure some day I'll get around to reading it properly. However, in my current fatigued state, trying to read that has pretty much melted my conscious. My head physically hurts now. ... I think I'm gonna go lie down for a while..[/quote] If you're a professional musician/soundman/DJ/whatever who makes his living with electronic sound reproduction devices all of the RaneNotes are required reading, and should be downloaded and kept for reference. The knowledge base therein is the equivalent of an associates degree in audio engineering.

[quote name='richy316' post='206534' date='May 26 2008, 08:13 AM']On the back of my Warwick Pro Fet 4 just above the power socket, well i'm not really sure what it supposed to do? I've read the manual but that does'nt really help in the slightest, so i'm putting it out to you wise folk to give me some expert knowledge on this?[/quote] It's used to prevent ground looping. [url="http://www.rane.com/note110.html"]http://www.rane.com/note110.html[/url]

[quote name='jjl5590' post='205138' date='May 23 2008, 12:42 PM']you say this, but the combo is exactly the same as the rig, just all kinda screwed together[/quote] That may be the case in some instances, but the vast majority of combos have a cabinet volume smaller than stacks for the drivers contained. That is very much not a good thing. One of the major shortcomings of most cabs is the use of too small a box for the drivers within. Going even smaller in a combo makes a marginal situation worse.

[quote name='chris_pokkuri' post='205139' date='May 23 2008, 12:43 PM']Whys that? What happens to the sound?[/quote] Since different drivers will have differing responses the result is that they will fight each other as much as they augment each other. The right way to do it is to use different size drivers each within its own enclosure, or compartment within a single enclosure, each optimized to operate as well as possible within a smaller segment of the audio bandwidth, so that their combined responses enhance each other.

[quote name='chris_pokkuri' post='205068' date='May 23 2008, 10:58 AM']Hmmm, now I am thinking maybe a 2x12 and a 2x10. Anyone have any experience playing with this setup?[/quote]Never mix different drivers operating within the same bandwidth.

You left out the most important consideration, which is sound. Combos almost always sound inferior, for two reasons. In the low frequencies they use smaller cabinet volumes for the drivers contained within, and smaller boxes result in less output and extension. In the midrange 2x combos place the drivers on the horizontal plane, and that results in poor midrange response and dispersion.

[quote name='bass_ferret' post='204014' date='May 21 2008, 07:31 PM']No. Its fact. I have been here long enough to know that everyone votes for what they are currently using, irrespective of the op.[/quote]Agreed. From an engineering standpoint the size of the cone has almost nothing to do with the bass response. I said I'd go with tens if I used a commercial cab because tens have superior midrange dispersion, which is the only characteristic that is primarily derived from the cone size.

None of the above. But if I had to settle for commercial cabs I'd use two 2x10s, vertically stacked.

[quote name='ahpook' post='201838' date='May 18 2008, 06:27 PM']um...it [i]is[/i] just a practise amp !![/quote] Seems OK for the price, especially considering the fifty odd quid worth of hyperbole in the ad copy.

[quote name='xgsjx' post='199083' date='May 14 2008, 04:41 PM']Should I keep in with the matching rig & go for something MB, or should I try maybe an Ampeg 410 or SWR 1x15. Cheers.[/quote] The right way to do it is to add another identical cab, and in use stack them so that the woofers are vertically aligned. From an audio engineering standpoint one should never mix different drivers operating within the same frequency bandwidth. This does of course go against what's accepted practice by both the bassplaying and cab manufacturing communities, but bassplayers by and large are not audio engineers, and manufacturers build to suit demand, not correct audio practice.

[quote name='gilmour' post='198755' date='May 14 2008, 09:36 AM']Go for an Omni Top 15 ... my omni 15TB is plenty plenty loud enough.[/quote] These are very different cabs. The O15 is designed to run with high sensitivity flat to 50 Hz, for a full bottom end well beyond what commercial cabs are capable of. The OTop 15 has even higher sensitivity but is flat to only 100 Hz, giving a vintage style tone but with a much higher output than vintage cabs.

[quote name='umph' post='197857' date='May 13 2008, 07:01 AM']Was thinking of going for a 2X15 that i'd be able to wire in stereo so would be able to choose between using one speaker for home or two for louder gigs[/quote] Not a practical notion IMO. Two 1x15s, much more so.

[quote name='mintybassman' post='194978' date='May 8 2008, 02:43 PM']Ah cross-over. Now we're talking... Would changing my EQ on my amp effect this? i.e. push the signals too high etc? Am i buying one or making one? Or am i naive to the humungous complexity of that task? What kind fo prices am i looking at for one? This is new territory for me.[/quote] Making is your best option. It's a simple circuit, only two parts, put them in a box with an input jack to go to the amp, outputs to each cab. Figure $50, a lot cheaper than new cabs. Finding the parts on your side of the pond is the most difficult part, very odd since the #1 source, Jantzen, is Danish.

A first order crossover at 150 Hz would route the lows to the 15, the highs to the 2x10, and keep the overall load at 4 ohms. Get component values at [url="http://www.lalena.com/Audio/FAQ/XOver/"]http://www.lalena.com/Audio/FAQ/XOver/[/url]

[quote name='stevie' post='187150' date='Apr 28 2008, 06:51 AM']Er, no... this is incorrect and quite misleading, not to mention confusing. The 6mm Xmax of the BP102 is a reasonable specification which will not lead to any loss of efficiency at bass frequencies. Higher excursions on a ten-inch driver might, but only because of a possible knock-on effect on cone area. Midrange efficiency is irrelevant for bass guitar amplification because there is always plenty to spare.[/quote]Tone is midrange. To get the extra xmax of the BP102 other T/S specs are also affected, resulting in a paltry 88dB sensitivity at 500 Hz. On it's own it sounds dull and lifeless, it needs to be used with a midrange driver to sound good. I don't recommend the BP102 for any of my full range speaker designs. OTOH, it does work very well in subs.

[quote name='mav' post='186324' date='Apr 27 2008, 05:15 AM']So two different opinions ? I was thinking if TE could push 500watts out of there 210 they would.[/quote]No musical instrument ten will take 250 watts broadband without exceeding xmax. The average is 50. [quote]Look for a driver with at least 5mm.[/quote] Very few tens go higher than 4mm, and those that do, like the BP102, have less sensitivity, so what you gain in one area you give back in the other.

[quote name='mav' post='181600' date='Apr 21 2008, 04:21 AM'], i'm thinking of replacing the speakers for something with more power handling like 300-400 watts 8 ohms.[/quote]The wattage rating of a driver has virtually no bearing on its output capability. That is determined by the drivers cone displacement, Vd, so unless you can find out what the Vd spec is for your current drivers there's no way of knowing what you need to replace them with to gain an improvement. [quote]As long as there a matching pair it doesn't matter?[/quote]The drivers must be matched to the cabinet volume and tuning frequency or they won't function properly.

Same answer as I gave you on TalkBass. The rules of physics are the same on both sides of the pond, so why ask exactly the same question on two forums?

[quote name='thinman' post='152701' date='Mar 6 2008, 04:14 PM']They look ace and it sounds like you're pleased with the sound. Just a point about the build: The plans suggest filling the cavities each side of the horn plates with pillow stuffing but I see you lined all the surfaces with the egg crate foam (which I was going to do anyway). Is yours OK without? I must admit I thought that by the time I'd lined all the surfaces there'd not be a lot of space to stuff. Shall I not bother?[/quote] I use pillow stuffing in the tight cavities where cutting small bits of foam would be time consuming, foam on the larger panels where it can be easily stapled in place. There's no functional difference.