Bill Fitzmaurice

[quote name='bass_ferret' post='433206' date='Mar 13 2009, 03:54 AM']Probably [/quote]+1. Why are you adding the 1x15? To get more low end. Google Hoffman's Iron Law. Simply put if you want to go lower you must either have a larger cab or a lot more power. If you have two cabs of the same size and same power the one can not go significantly lower than the other while maintaining the same output level, irrespective of what size drivers you use. This goes to laws of physics, which is not trumped by either opinion or advertising. Adding a second cab will get you more output, but so long as it is the same size and driver displacement it really doesn't matter all that much what's in it. And since the average 4x10 has more displacement than the average 1x15 adding another 4x10 will give you more output than adding a 1x15. Which is what I said five pages back.

[quote name='redstriper' post='430714' date='Mar 10 2009, 12:57 PM']OK - so which specific cab/driver combination would you recommend?[/quote] One that uses a fifteen with no less than 8mm xmax. In the electric bass genre you're as likely to be able to get that information as for the Queen to give you her crown. I believe Alex is currently the only UK source that divulges the specs on the drivers he uses.

[quote name='Sharkfinger' post='430158' date='Mar 10 2009, 06:03 AM']Going back to the original question, what advice would we give fekalizatorius?[/quote] The point of this overblown exercise has been that adding any 1x15 willy nilly will as likely work no better than adding a 2x10, and the 2x10 will give a better modular rig. Fifteen inch drivers that actually work better in the low end than his current 4x10 do exist, the trick lies in finding out if one of those drivers is what's contained within a particular cab.

[quote name='stevie' post='429495' date='Mar 9 2009, 12:05 PM']I’m not suggesting anything other than that there is a relationship between fs and cone size.[/quote] Only in the most peripheral way. Size and fs would only be somewhat proportional if all cones were made of the exact same material. They aren't. Otherwise eights with fs values an octave lower than eighteens, and vis-versa could not exist, But they do. To suggest that driver size and fs are intrinsically linked displays lack of a fundamental understanding of driver design. [quote]OTOH, given the ratio of cake height to radius (which is approximately constant between the Pie and the Gateau[x]) what would happen, theoretically, if I had a cylinder with a smaller surface area (cake top) but greater 'excursion' (cake height) - e.g something like Tesco's Value chocolate sponge roll.[/quote] A simpler analogy is that sixteen one ounce weights and one sixteen ounce weight both weigh a pound. Even better: you'll get just as drunk after quaffing two pints as you will with one quart.

[quote name='joegarcia' post='428689' date='Mar 8 2009, 12:54 PM']What exactly is wrong with them then?[/quote] Guitar drivers loaded in a cab of half the volume required shoddily built from inferior materials. But otherwise OK.

[quote name='Mr. Foxen' post='428668' date='Mar 8 2009, 12:29 PM']Did it have some advantage like better treble dispersion, or was it just how to fit speakers in a different sized box?[/quote]Most likely too much weed. California in the '70s, dude. Fender cabs were never shining examples of how to build bass cabs, more often than not being the opposite. This oddity represents their nadir.

[quote name='Mr. Foxen' post='426626' date='Mar 5 2009, 03:12 PM']The fact that they are in the same enclosure might defeat some of the 'advantages' of the 4 vertically arranged layout though.[/quote] There are no advantages to four vertical drivers when there are four more adjacent to them.

[quote name='Sharkfinger' post='426154' date='Mar 5 2009, 08:51 AM']So what I'm getting from this, right or wrong, is that by a rule of thumb the more cone surface area the more LF is produced,[/quote] Surface area is only half of a two part equation. What counts is surface area (Sd) multiplied by excursion (Xmax), the result being displacement (Vd). However. as your assumption is shared by the vast masses, it's one capitalized on by the marketeers, who want you to think that you must go larger to go lower, and in so doing hopefully expanding the contents of their coffers. The other side of that coin is that even amongst manufacturers that do possess a social conscience none are going to refuse to build anything that isn't justifiable so long as there's demand for it.

[quote name='Mr. Foxen' post='426571' date='Mar 5 2009, 01:58 PM']In two columns of 4 vertical speakers. Haha, I see at least one of Bassferret, Claber and BFM coming into this thread to suggest that.[/quote] It doesn't matter, it won't sound any different. The fault with an 8x10 lies in having drivers side by side, not in how they're wired. [quote]Anyway, I have an Ashdown 8x10 that is 4 ohm, and was thinking that if I put an Ampeg style thing into it, so I can run it as two 4x10s and can run both my lower powered valve heads that only do down to 8 ohms into it.[/quote]Unlike SS valve heads have no minimum impedance load, they have a maximum impedance load. Your proposed mod is probably more trouble than it's worth.

[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.