Bill Fitzmaurice

[quote name='JonnyM' post='221059' date='Jun 17 2008, 08:16 PM']Can't resist posting these pics... [attachment=9739:1974_07_21.jpg] [attachment=9740:grateful..._sound_1.jpg] The backline IS the PA (the bass "rig" is the tallest stacks the right and left of the drums: 2 vertical stacks of 15's, 18 per stack... (I have an LMII and 2x10 Traveller and when I need to, I'll get another identical 2x10 to stack vertically... )[/quote] The Dead were probably the most technically literate band of all time. They did their homework for sure. Their most ingenious invention was to use two mics side by side, wired reverse-polarity. They'd sing into only one, but any foldback was equally received by both, where the reverse polarilty cancelled out the signal, allowing outragous levels with no feedback.

[quote name='stevie' post='220863' date='Jun 17 2008, 02:19 PM']Studio monitors from ATC, Quested and Dynaudio, by the way. And when these guys need four drivers, guess what?[/quote] Stevie, you'd have a lot more success arguing the fine points of loudspeaker design if you understood any of them. If you did you'd know that drivers may be placed on the horizontal plane if they are crossed over below the frequency that is 1 wavelength at their CTC spacing. Debating the laws of acoustics is a waste of my time, as being laws they are not subject to debate. I'm usually quite patient at explaining said laws and how they affect gear choices to those who have an interest in furthering their education. OTOH you strike me as one who clearly has already acquired all the knowledge he ever cares to, and that being the case please refrain from wasting any more of my time.

[quote name='stevie' post='220772' date='Jun 17 2008, 12:31 PM']What exactly is this "flawed standard"? Can you be more specific?[/quote] Foremost, placing drivers horizontally. For an example of how drivers should be placed investigate the circa 1950 PA installation in St. Paul's Cathedral in London, which was only recently upgraded because it worked so well for a half century plus despite being in the most difficult of environments. Assumption is Jim Marshall was not a parishoner.

[quote name='chris_b' post='220334' date='Jun 16 2008, 09:17 PM']At the risk of starting another argument here..... I repeat, it is my experience over the last 10 years that you can successfully run a 2x10 and a 1x15 together and it is my current experience (of 3 months) that I am successfully combining cabs from different manufacturers.[/quote]No one is saying that you cannot use different driver sizes or cabs from different manufacturers covering the same bandwidth and not have a useable result. OTOH if the goal is the best possible result that is obtained by either using identical drivers/cabinets or by using different size drivers in a sytem that has been engineered from the ground up to do so. Using the Chinese Restaurant Menu Method (as in pick one item from column A, one item from colunm is not sound audio practice.

[quote name='lowhand_mike' post='219952' date='Jun 16 2008, 10:57 AM']think bill means that as the "norm" for bass amps and indeed guitar amps was started back in the day as horizontal 2x10s and 4x10s when audio engineering was a little less refined it has been carried through,.[/quote] +1. The engineering used by the vast majority of musical instrument cabs has not changed significantly since the mid 1970s, and it was 30 years obsolete even then. If either Leo Fender or Jim Marshall had possessed beyond a rudimentary knowledge of audio theory in general and loudspeaker design in particular the vast majority of musical instrument speaker topologies introduced since 1955 would never have appeared in the first place. Fender was a machinest who didn't even play guitar or bass, and Marshall was a drummer. Their method of speaker design was 'stick some drivers in a box'. Unfortunately they set a flawed standard that still dominates the marketplace today.

[quote name='chris_b' post='219591' date='Jun 15 2008, 08:16 PM']2x10's have sat on top of 4x10's and 1x15's for years with no trouble[/quote] 'No trouble' is a matter of opinion. Mine is that of a bass player who also happens to be an audio engineer. As for specific examples, that would be the simultaneous using of any two cabs that don't have identical phase response. Since no two cabs that don't use identical drivers in identical alignments can have identical phase response that makes every use of non-identical cabs a specific example. I'm not saying they can't sound acceptable, but they would sound better properly matched. Amongst other things.[quote]Wow!! Dismissing the efforts of an entire billion dollar industry at a stroke... nice one![/quote] Just the instrument cab industry. The hi-fi, theater and PA guys got it right a half century ago, the instrument market segment is a wee bit slow on the uptake.

[quote name='bass_ferret' post='219442' date='Jun 15 2008, 03:55 PM']Bill may be assuming that you are using a crossover for these cabs but I suspect you are intending to put the full signal through both. As has been said many times putting the same signal through different cabs can produce unpredictable results and is likely to sound bad which ever way you stack them.[/quote] I'm assuming he is not using a crossover. Tens will naturally have a wider midrange dispersion angle and a higher frequency response than fifteens, so the caveat applies with or without being crossed. [quote]Then how come the workhorse rig for years was a Trace 4x10 on top of a Trace 1x15 both fed with the same signal from Trace Amp?[/quote]Because no manufacturer had, or has for that matter, any incentive to do better when they sell all the mediocre high profit margin junk they can crank out. And bassplayers are artists, not engineers, so by and large they just don't know any better.

[quote name='Youngatheart' post='219318' date='Jun 15 2008, 12:50 PM']Is there any reason why you can't stack a 1x15 on top of a 2x10. Trust me there is a sensible reason for me asking this [/quote] That puts the non-directional lows closer to ear level and the directional mids down below your knees. Perfectly OK if you're in the habit of playing whilst standing on your head.

[quote name='Mottlefeeder' post='217129' date='Jun 11 2008, 02:31 PM']I agree that bass players use EQ, but their initial stance is usually 'Can I hear it with the EQ flat first?'[/quote] Chances are they never do, since almost no amp around is actually flat. Most have some sort of pre-shaping built in. [quote]My personal view of EQ is that it is like a car accelerator pedal. If you have it at maximum all the time, then something is wrong[/quote]Quite right. The thing about EQ is that if you're using it correctly you should be cutting as much as you're boosting, and neither cutting nor boosting at anywhere near full capacity.

[quote name='rodl2005' post='216570' date='Jun 11 2008, 02:31 AM'][quote]"I had personal experience of this with a Peavey 115BW. I added a Peavey 2x10 and it sounded sh*t - much better with each individual cab, and whats more the 2x10 was actually deeper so I sold the 115 and got another 2x10."[/quote] IME this MAY've been due to the cabs/spkrs being outta phase. [/quote] Maybe, though I believe you are referring to polarity, which isn't the same thing. With reversed polarity the two cabs would be out of phase pretty much through their entire bandwidth. But even with like polarity two dissimilar cabs will be out of phase at some frequencies. That's because the phase response of every speaker varies with frequency. The only way to be sure that two speakers have identical phase responses, and therefore won't interfere with each other, is for them to be identical.

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.