Bill Fitzmaurice

[quote name='EBS_freak' post='425690' date='Mar 4 2009, 08:09 PM']For what it's worth... I would guess the majority of bass players don't care.[/quote] They should. He who knows how things work can see past the phony baloney claims of the marketeers. He who who does not is at their mercy.

[quote name='stevie' post='425094' date='Mar 4 2009, 09:16 AM']Bill, you must have missed my earlier post.[/quote] No, I just ignored it. [quote]Bigger drivers, with their lower resonant frequency and superior radiation impedance, are by nature more efficient reproducers of low frequencies.[/quote] Driver size and Fs are independent of each other. Radiation impedance is determined by system Sd, and the air doesn't care if said Sd is comprised of one larger driver or many smaller ones. However, system efficiency is determined by the sum total system motor strength and Sd, so the multiple motors of smaller drivers can and will allow a grouping of smaller drivers to not only exceed the total output of one larger driver via higher total Vd, they will also allow them to do so with less input power via higher sensitivity. The downside of doing so is the generally higher cost of multiple smaller drivers compared to one larger driver when they are of equal quality. However, multiple lower quality smaller drivers can deliver equal or better results than a lesser number of higher quality drivers at a lower overall cost. That fact was the basis for the development of the SVT, although it was certainly not the first example of multiple driver usage.

[quote name='Sharkfinger' post='423161' date='Mar 2 2009, 08:19 AM']Also have a relevant (probably stupid) question: if driver diameter has minimal effect on frequency generated and it's all down to cabinet tuning, why are PA subs traditionally loaded with 15" or 18" drivers, especially in higher power applications?[/quote]Tens and twelves capable of the same response do exist, and with equal total Vd will give equal output. But since it would take more of them to do so it's more cost effective to use fifteens or eighteens. Customer perceptions also are just as pervasive in PA as in electric bass cabs. Most buyers assume that a cab loaded with larger drivers will go lower, so that's what the manufacturers sell. OTOH the most expensive, and best performing, pro-touring subs are folded horns, and in those twelves are the norm. Customers spending upwards of $3k per cab tend to pay more attention to how a cab works rather than what size drivers they employ.

[quote name='bassplace' post='421452' date='Feb 27 2009, 07:33 PM']Aren't tweets an issue too increasing the sensitivity rating?[/quote] They shoujdn't be. The AES accepted method of rating sensitivity is that of the woofer above f3 where the driver is operating in pistonic mode. That generally means from about 100 to 300 Hz, and it removes cone break up and tweeters from the equation. Many bass cab manufacturers routinely ignore that protocol, and rate their cabs at whatever the highest sensitivity is at whatever frequency it may occur, so inflation of as much as 8dB is not at all unusual. At the same time it's de rigeur for them to claim low frequency extension at least 10Hz lower than actual. That sort of shell game couldn't occur if SPL charts were required to back up their claims. I estimate at least half the cab manufacturers don't have the charts to post to begin with, while those who do would rather the results never see the light of day.

[quote name='northstreet' post='421321' date='Feb 27 2009, 03:55 PM']So..........call me Mr Stupid, but if I understand this correctly, the best sound will be obtained by stacking two cabinets, largely regardless of what's in them? The bottom cab will give the bass, the top cab will give the mid-range, and the combined cone area gives volume and perceived bass response.[/quote] More or less, yes. Adding a second cab increases output significantly, with no changes to the amp, and having a higher rig makes it easier to hear the mids and highs. But the frequency duties aren't split to the extent that the bass comes from the lower cab and the mids and highs from the upper, it just seems that way from your vantage point so close to the rig.

[quote name='alexclaber' post='415339' date='Feb 20 2009, 09:23 AM']I think GB made a real mistake with having one light come on for both the soft compression and the final output limiter.[/quote]But they did save 20 cents per rig. Add it up for a year's production run and you might have enough to buy beer for the company barbeque. [quote]Am I being too precious/paranoid, or do I need to get another rig for the jams?[/quote]Running like that won't hurt the amp, and at least you know your speakers are being protected.

[quote name='far0n' post='421024' date='Feb 27 2009, 10:41 AM']I think the best I've had was my Eden D410XLT at 106db. Haven't come across any louder than that from the main manufacturers.[/quote] Without an SPL chart claimed sensitivities aren't worth doodly squat. Eden in particular is famous for making claims that stretch the bounds of reality. Ampeg, OTOH, is very honest. Considering that all manufacturers use the same type cabinets and that there are no magic drivers commercial cabs claiming more than 2 or 3dB higher sensitivity than an Ampeg of similar design should be dismissed out of hand.

[quote name='andrewrx7' post='420828' date='Feb 27 2009, 07:53 AM']Pull the plug from the 15incher, and the bottom thump noticable drops. Pull the plug from the 4x10, and that higher end definition clearly drops. Combined - best of both worlds.[/quote] Your observations are correct, but not the conclusions drawn. If you were to stack a pair of 4x10s and a pair of 1x15s, or a pair of anything for that matter, similar results would always ensue. Unplug the bottom cab and the bass response will fall. Two reasons. First. the raised impedance and reduced cone area reduces output by at least 5dB. When output drops you don't hear bass as well, see: Fletcher-Munson equal loudness curves. Second, when run alone the height of the top cab above the floor is sufficient to de-couple the system from the boundary reinforcement offered by the floor, and it does so in the midbass where bass impact is perceived to originate from. With both cabs plugged in the cones in the top and bottom cabs operate as one in the low frequencies and there's no coupling loss. Unplug the top cab and the midrange and high-frequencies will fall. Again, two reasons. The first is that same cone area and impedance situation as before. The second is that mids and highs are very directional. and if the source is on the floor they simply pass you by unheard. The notion that adding a 15 will fill in the bottom with a 4x10, or vis-versa, gains credence when one performs the same exercise as you did. But assuming you don't happen to have a pair of 1x15s and a pair of 4x10s lying about to perform the same experiment with different combinations of cabs you simply have no way of knowing that you'll get similar results no matter which combination you may use, including putting a 1x15 atop a 4x10.

[quote name='markdavid' post='420338' date='Feb 26 2009, 02:40 PM']if I upgraded to a 60W amp for practice would I get any increase in low end.[/quote] Yes, like night and day, totally worth it. Since you posted the same question in two forums it seems you want to go with whichever gives you the answer you like best. The least I could do is give you two answers to choose from.

[quote name='bassman2790' post='419955' date='Feb 26 2009, 06:16 AM']Although the 1 x 15 gave a different tone, it added no more bottom end.[/quote] +100. The assumption is made that the larger driver size will result in a lot more low end. It won't. The low end output capability of a cab is mainly determined by the total volume displacement of the drivers, Vd. The Vd of the average 4x10 is about 400 cc, that of the average 1x15 300 cc. If one is going to get more LF output by adding 1x15 to a 4x10 the 1x15 should have considerably more Vd than the 4x10, not less. Where portability is desired for small gigs I'd add a 2x10, not a 1x15. Preferably the same brand, using the same drivers, at twice the impedance of the 4x10.

[quote name='6h5g' post='416320' date='Feb 21 2009, 02:16 PM']what does this mean?[/quote] That the manufacturer succumbed to the lure of advertising hocum. In a perfect world only RMS ratings would be allowed, but it being imperfect those on the advertising end love to use other 'ratings', such as peak, music power, peak music power and so forth, all in an effort to make the amp appear as powerful as they can. When comparing amps only RMS should be considered, everything else ignored.

[quote name='Mr. Foxen' post='414789' date='Feb 19 2009, 04:39 PM']PA columns can be pretty doom: Dispersion doesn't matter when everywhere is in front of your speakers.[/quote]Even at close range having them horizontal isn't good, the tone will change literally every few inches as you walk across their soundfield. The main deficiency of columns way back when was they were intended to be stood on the floor or stage, and that seriously detracted from their function. They work best for PA on a stand that allows them to be lifted high enough so that the lowermost part of the cab is at ear level for the close-in audience, the upper drivers carrying over the heads of the audience to reach the back of the room, with ten degrees or so of down tilt. Unfortunately stands to allow them to be easily set up that way didn't exist.

[quote name='xgsjx' post='414592' date='Feb 19 2009, 01:42 PM']I just rememembered, I used to have as pair of Vox 4x10 pa speakers when I was in my early 20's. They was each about 5' high & about 1' wide & all vertically aligned. Just thought I'd share that.[/quote] The best commercially built bass cab I ever owned wasn't a bass cab, it was a 1968 Kustom 4x12 PA column w/tuck and roll Naugahyde upholstery. In 1970 I had a chance to compare one side by side with an original Fridge. The Kustom was better. Next time in London drop into St. Pauls and check out the PA. Originally installed circa 1950 it was a shining example of how well vertical sources can cope with even the most difficult venues. It was upgraded a few years ago with modern electronics and drivers but the original column speaker design remains pretty much original.

[quote name='skankdelvar' post='414448' date='Feb 19 2009, 11:16 AM']I hope that the vertically aligned SVT 8x10 will come with a free hard-hat...[/quote] One of the regulars on my forum reported how he internally divided the 4x12 guitar cabs used by his sons band into two vertical sections, then added a switch to run either just two vertical drivers or all four. He did not tell them what the switch did. They vastly prefer the sound of the two drivers only. Four tens vertically aligned, in two well designed 2x cabs for ease of transport, will outperform an 8x10 in every way. They'd also cost a lot less, and be far easier to transport. Which option do you think bass cab companies would rather sell? And which do you think those same companies will provide their endorsers with to push said sales? Engineering issues aside the bottom line with any manufacturer will always be the bottom line.

[quote name='Lfalex v1.1' post='414016' date='Feb 19 2009, 06:08 AM']Which was probably primarily driven (no pun intended!) by an entirely practical consideration; Stability.[/quote] -1. Leo placed drivers side by side, starting with combos in the 50s, for two reasons. One was to cosmetically match the width of the amp section. The other is that, not being an audio engineer, he wrongly assumed, as would anyone, that a wider radiating plane would give wider dispersion. In the 60s when early portable PAs appeared many were columns, from sources such as EV and JBL, who knew that vertical sources gave the widest dispersion. By the early 1970s they disappeared, because the average buyer couldn't understand why vertical sources gave wider dispersion than horizontal, and demanded instead trapezoidal PAs intended for horizontal arraying. Rather than stand on engineering principal PA manufacturers instead built trap cabs and took the money. Trap cabs only recently disappeared from the pro-touring genre, replaced by line arrays, as the current crop of pro-touring PA operators are for the most part well versed in audio theory and know enough not to use horizontal sources. Thanks to the internet the average muso as well will eventually know that horizontal sources are bogus and demand for vertically aligned driver bass and guitar cabs will drive the 'old standards' off the market.

[quote name='Boneless' post='413769' date='Feb 18 2009, 06:48 PM']What about 4x10s? I thought they were one of the most efficient solutions for bass When they were introduced, they were seen as kind of a revolution, and while many years have surely passed by, I can't really see the problem with 4 identical drivers in a well designed cabinet [/quote]Drivers mounted side by side leads to comb filtering in the high frequencies, and of more significance halves the dispersion angle in the midrange compared to a single driver or a vertical alignment of multiple drivers.

[quote name='redstriper' post='413686' date='Feb 18 2009, 05:31 PM']Why would I try a 2 x 15 when I'm looking for lightweight cabs?[/quote] OK, how many 1x8 or 1x6 w/high pass filtering did you try along with 1x15s w/low pass filtering? When the question posed is whether a top and bottom cab combination have been optimally engineered to acoustically complement each other those options would have to be made available to the consumer. They aren't. The options that are offered are only matched in cosmetics and footprint. Your response is to a different question entirely, that being whether you can run a 2x10 and 1x15 together with an acceptable result. Obviously the answer is yes. Whether it's the best possible sounding option one could only say if you could try the above mentioned 1x8/1x15 or 1x16/1x15 with appropriate crossover, but you can't, so you'll never know. As for Alex's perceived concessions to the conformity game, I'm sure that they will never include a 2x10 to be used with a 1x15, nor a 2x10 with horizontally aligned drivers, nor a 4x10, period. He knows better, and that's more than you can say for the usual sources.

[quote name='redstriper' post='413552' date='Feb 18 2009, 03:03 PM']I tried a lot of cabs and combinations regardless of looks and found the single 15 and 2 x 10 cabs work well together and make a sound that I'm very happy with, although two 15s are my preference.[/quote]How many 2x8 or 2x6 cabs with vertically aligned drivers and high-pass filtering were you able to test matched up with a 2x15 with low pass filtering?

[quote name='Boneless' post='413070' date='Feb 18 2009, 09:06 AM']Maybe from an "audiophile" point of view. A 2x10" cab may not perfectly acoustically pair with a 1x15", but it's a common solution: there must be a reason for it, and the reason is that many people actually like this speaker configuration.[/quote] Your reply is the proof of the proverbial pudding. Cab manufacturers build what sells, what sells is what the consumer thinks 'looks right', and what 'looks right' is what they're used to. Since virtually every manufacturer turns out the same cookies using the same cookie cutter the opportunity for the average player to hear a superior product simply does not exist. And no manufacturer, save a small entity like Alex with his barefacedBass cabs, is going to invest in the R&D and tooling for a superior product that won't sell because it doesn't 'look right', especially when same old same old continues to go out the shop doors.

[quote name='Mr.T' post='413038' date='Feb 18 2009, 08:41 AM']i.e. Trace designed their 1x15 and 2x10 as a set. I assume (some) other manufacturers do likewise.[/quote]Only to the matter of sizing them to the same width for stacking. A 1x15 and 2x10 truly engineered to work together does not and never has existed. Driver displacement and cabinet size requirements increase exponentially as frequency goes down, so while a 1x15/4x10 is a favorite combination the ratio is backwards; a well engineered system would run two to four 15s with one 10. A proper match for one 15 is one eight, or six. 'Matched sets' is a purely cosmetic matter, proper audio engineering is not a consideration.

[quote name='Jamesk86' post='411239' date='Feb 16 2009, 10:55 AM']why? The sub 15 concetrates on more on the lower end of the projection[/quote]-1. The main limiting factor to low frequency output isn't driver size, it's cabinet size. A small 1x15 won't improve low end output in this case. It would be as effective as adding a pair of oars to a motorboat in hopes of going faster.

[quote name='Pookus' post='410410' date='Feb 15 2009, 03:34 PM']My current rig is an Ashdown ABM900 and 8x10 cab. I run the 810 from one of the channels from the ABM900 - which means I have another channel spare. There are two ways I can go 1) drive the sub bass cab from the other channel possibly with a crossover or 2) get a powered sub and take the signal from the sub out. Ideally I don't want to spend much and also am capable of building my own cabs. Please help me make up my mind![/quote] For a sub to have significantly better LF performance than your 8x10 it would have to be twice as large. There's no getting around that fact. OTOH if you do build/buy a true sub you won't need an 8x10 to handle the mids and highs, a 2x10 would be plenty. In short, if you can't get the lows you want from an 8x10 it's time to rethink the entire system from the ground up.

[quote name='Rich' post='407587' date='Feb 12 2009, 08:47 AM']Certainly from personal experience, my rig sounds loads better with two 1x15s than it did with a 1x15 plus a 2x10 -- but YMMV. As the man said, suck it and see![/quote] +1. There are so many variables involved that it's impossible to predict what any particular combination will do. The advantage to using paired identical cabs is that you'll get just what you have now, but a lot more of it. Those with 1x15s who want to add tens to the mix assume that the top end will be better. For a variety of reasons it's just as likely that the opposite will be the result.

The BP102 will likely have a very different response than the Eden, probably much weaker in the mids.

[quote name='casapete' post='404391' date='Feb 9 2009, 10:38 AM']These new cabs look interesting - 1000 watts, 70 lbs etc. Anybody got one - what are they like? (apologies if this thread already posted!)[/quote] They're bass reflex cabs, using the same cabinet technology as every other bass reflex cabinet in existence, loaded with dynamic drivers that use the same technology as every other dynamic driver in existence. That means the difference between them and every other 4x10 of similar size will be slight.