Bill Fitzmaurice

Mixing drivers is like a box of chocolates: you never know what you're going to get. If you don't like the sound of your current cab get out shopping, try as many as you can, buy the one you like the best. If one doesn't go loud enough buy two.

[quote name='VTypeV4' timestamp='1418466211' post='2630384'] Did anyone else clock the 'Turbosound' badge on the cab..? I would like to think it's of some significance...Or maybe Turbo simply desiigned the cab. [/quote]If the engineers at Turbosound had any input into the design the badging would be rotated 90 degrees, and the result would look like this:

[quote name='spacey' timestamp='1417513832' post='2621062'] his voice well lets put it kindly, its gone. [/quote]It wasn't when I saw him last February, for the first hour anyway. He can't maintain full tilt for a two hour concert, so he does have to back off after a bit. But he still managed to hit it all at the end of the night with [i]Won't Get Fooled Again, [/i]scream and all. I've seen every major act over the last 50 years, and no doubt [i]The Who [/i]is the best band ever. No offense to Mick and Keith.

[quote name='Beer of the Bass' timestamp='1416998988' post='2615829'] I have an EA Wizzy 10 which uses one and it does seem to make the orientation of the cab a little less critical, rather than only sounding right when it's pointed straight at you. [/quote]That's because the whizzer acts as a 4 inch midrange driver. Beaming occurs when the driver cone is larger than one wavelength. With the 13 inch cone of a 15 inch driver that's above roughly 1.2kHz, with a 4 inch whizzer that's above roughly 3.5kHz.

[quote name='JohnOH' timestamp='1416963345' post='2615641'] I seem to recall reading something to the effect that smaller speakers physically close together can beam like one larger speaker, is that correct? Is that why you recommend vertical stacking? [/quote]Two speakers side by side will have half the horizontal dispersion angle as one, up to the point where they're one wavelength apart center to center. Above that frequency, roughly 1250 Hz with tens, the situation worsens, as they no longer act as one larger driver but rather as individual sources, and the result is comb filtering. Response literally changes as you go across the soundfield, with no two listening positions being the same. Placing the drivers vertically remedies both of those issues, as they're shifted to the vertical plane, where the audience doesn't reside. [quote]my preference for sealed speakers extends to listening to recorded music too. It's hard to quantify but to me, sealed sounds more coherent.[/quote]If sealed sounds better it's because the ported cabs you listened to were poorly done, or improperly EQ'd, or both. In blind testing of well designed speakers EQ'd to identical response and level matched even the most golden eared audiophiles can't tell one from the other, to their extreme chagrin.

First off, no fifteen will give useful response to 4kHz. On-axis you'll hear something, but off-axis the highest a fifteen will go is perhaps 1.5kHz. Even twelves aren't much good past 2kHz or so. If you want to run without a midrange driver you need to go with tens. Second, your preference for sealed versus ported has nothing to do with the cabs, everything to do with the instrument. Double bass just doesn't go low enough to require the lows that a ported cab produces. For the same reason you don't need huge xmax, nor do you need to be concerned about the sensitivity below 80Hz. Frankly I can't imagine a worse cab for double bass then an Acme, unless you don't want your double bass to sound like a double bass. You do need to be concerned about the mids. For these reasons I'd use the Eminence B102 in a 30 liter (net) box. It's whizzer cone gives it useable off-axis response to 4kHz. I'd do them as 1x10s, stacking vertically as many as you need. You could do a vertical 2x10 in 60L net, but IMO it's easier to carry two small cabs than one large one. If you want flat response to 50Hz you could put a B102 into a 60L ported box tuned at 45Hz, but IME double bass doesn't need to go that low.

[quote name='lowendgalore' timestamp='1416785681' post='2613642'] Tonally identical though yeah? [/quote]Yes, if the specs are otherwise the same. Sometimes they are, sometimes they aren't.

[quote name='Dad3353' timestamp='1416756383' post='2613200'] All things being equal elsewhere, the 4 Ohm cab will sound slightly louder. [/quote]Only at small signal levels. Maximum output is determined by the driver xmax. That's usually the same for 4 or 8 ohms, so maximum output is also the same.

[quote name='Musky' timestamp='1416438710' post='2610353'] It doesn't make the blindest bit of difference to how the cabs sound, but it does for some people's purchase decisions. [/quote]It does, because if an Eden or DNS 410 actually had 106dB sensitivity then one of them would be as loud as two Ampeg 410s. If they weren't trying to give that impression to prospective buyers they'd not make the claim. [quote]I seem to remember Alex found himself in a quandary regarding this when he started up Barefaced - how to honestly give the specs for his range without resorting to BS or making his cabs appear a poor relation to his competitors.[/quote]It is a difficult choice, which he probably handled in about as good a fashion as possible. Still, if it was me, I'd post measured SPL charts, and make it clear to prospective buyers why other manufacturers don't.

[quote name='chris_b' timestamp='1416404917' post='2609822'] On the other hand. . . . these optimistic, exaggerated or just plain false specs didn't stop Eden and many of the other makes sounding great. I get that to many the paper work is important, but it's not as important as what the thing sounds like. [/quote]I hear this argument over and over again, and it doesn't hold water. A lie is a lie. If you go to a butcher and order a pound of steak, and [i]pay[/i] for a pound of steak, and you actually get a 12 ounce steak, you were cheated, no matter how good the steak tasted.

[quote name='JTUK' timestamp='1416387778' post='2609567'] I think boom is a problem of the cabs, mostly... [/quote]Some cabs are prone to boom, but so are some rooms, where you'll get boom no matter what cab you have.

[quote name='Beer of the Bass' timestamp='1416397504' post='2609709'] Yes, I think most manufacturers do it. I have a small 1x10" which the manufacturers claim has 102dB sensitivity, 126dB max SPL and a usable frequency response down to 45Hz. I don't believe any of those for a moment! [/quote]Technically all of that is possible. It could have a midrange peak at 102dB sensitivity, it could reach 126dB in the midrange, and it could have useable response to 45Hz, meaning that it's down 10dB from average at 45Hz. But that's all specmanship. There are specific rules set forthe by the AES as to how speaker measurements are to be made and quantified. Virtually every manufacturer ignores them. One honest manufacturer is Ampeg, so they can be condsidered as the spec benchmark. When you see sensitivity and/or frequency response specs that are more than a couple of dB or Hz off from what a similar Ampeg product is rated at you can safely assume that the claims are bogus.

I do the same with my Superfly, each preset with the same EQ save for one filter that I set at -9dB, at six different frequencies. When I encounter boom I can scroll up through the presets until I find the right one to suppress the boom in that room. Then I can tweak the other sliders to get the final tone that works best, though I seldom have to do much once the boom frequency is notched out.

[quote name='Musky' timestamp='1416355308' post='2609447'] A few years back when Alex pointed out that the specs quoted for a cab made by a respected manufacturer couldn't possibly true, said manufacturer did the decent thing, apologised and amended the specs. In mitigation they said they did it because all their competitors were lying as well... [/quote]Aguilar, if I recall correctly. Eden was well known for blatently lying about their response and sensitivity specs when still being run by Dave Nordschow, and Nordschow continues to do so with his DNS line. Old habits die hard.

[quote name='FuNkShUi' timestamp='1416318496' post='2608974'] So Bill, sorry if this is a slight derail, if you wanted a Amp with the most volume "out front", what measurement would you be looking at? SPL? [/quote]SPL is what you hear, not watts. There is no direct correlation between power and SPL. One can calculate the maximum SPl that a given amp and speaker combination will deliver if you have the required data, but no speaker manufacturer that I know of provides that data. If you know the T/S specs of the driver being used and have detailed cabinet dimensions you can calculate both the frequency response and maximum SPL of the speaker, but most speaker manufacturers won't tell you what the driver specs are.

[quote name='skidder652003' timestamp='1416316514' post='2608929'] doesnt the wattage have to be 10 times as big to just double the DB level, [/quote]It does. More accurately, it takes a 10dB increase to be perceived as a doubling of volume, which requires a tenfold increase in power.

[quote name='LukeFRC' timestamp='1415800503' post='2603903'] and would I be right in guessing that your ultimate cab wouldnt be a bass reflex either? [/quote]I play a bass reflex cab, a Jack 12 Lite. But it's also horn loaded.

[quote name='LukeFRC' timestamp='1415776932' post='2603566'] I mean it's common in PA land- just not bass world yet. [/quote]So is line array technology, midrange drivers, crossovers and cabinets that are actually large enough for the drivers that are contained within. To be frank, the engineering used by most electric bass amp and cab manufacturers is archaic, but as long as they sell they'll continue to be made.

There is no simple answer. There is another point to ponder, though, that being equal loudness. The lower the frequency the harder it is to hear, so to compensate for that you might use EQ. EQ eats up headroom like nobodies business, both in terms of driver excursion and amplifier power. For that reason I'm hesitant to sacrifice either excursion capacity or speaker sensitivity in the 40-50Hz range, where one is most likely to apply EQ, in favor of above 60Hz, where you're less likely to boost EQ.

[quote name='Ruds' timestamp='1415631525' post='2602139']. Maybe I'm just overthinking, and in practice this is not important, or I'm overlooking something. [/quote]It's not that xmax isn't important, it's that you don't have to consider it along with the thermal power rating, frequency response and sensitivity in a juggling four specs scenario when the maximum SPL chart wraps it all up in one neat package. It also helps to know that you don't need for a cab to have consistent maximum SPL down to the lowest fundamental. Where you run into a compromise situation with respect to a design that anyone can use is not knowing if the end user has a four string, five string or a drop tuned six string.

Any of my 2x12 designs would suffice. They're made from 12mm plywood, so they're light weight. They've also withstood falling off the back of a pickup truck at 60MPH with only scraped paint to show for it. I'd venture that barefaced are just as durable. What you make a cab out of is of far less importance than how you make it.

[quote name='owen' timestamp='1415563197' post='2601516'] One speaker firing out of the front and one out of the back (presuming out of phase with the front one)[/quote]That would result in their cancelling each other. They would have to be in phase/polarity. For best results the rear driver would have to be low-passed, probably around 250Hz, where the rear radiation pattern is omni-directional. Some will suggest that having the rear driver full range would give good dispersion, but the result would be severe comb-filtering, with the cab sounding different at every possible combination of both the cab placement and the listener position, as the front and the reflected rear waves meet at constantly shifting degrees of phase based on the wall distance and listening position.

[quote name='Ruds' timestamp='1415547203' post='2601329'] But, if I know the cab is going to be used mostly for electric bass, and I know something about this signal, wouldn't it be more precise to use this information to estimate the limits of the enclosure on a more practical situation? [/quote]I don't. I look at SPL, Maximum SPL and port velocity charts. I don't worry about excursion per se, as it's just a means to the end that's seen in the Maximum SPL chart. Looking at the excursion chart shows only one dimension of a three dimensional result. The main benefit to looking at the excursion chart is in learning how it fits into the overall result, including how tuning affects excursion, but after a few decades of designing speakers that's second nature.

It's the maximum SPL chart you should be looking at, not the excursion chart. Maximum SPL accounts for sensitivity, excursion and thermal power. With a 5 string tuned at B your maximum demands lie at the 2nd harmonic, 62Hz. However, obtaining maximum SPL at 62Hz will come at the cost of sensitivity, and therefor output, below that, so you must compromise to get the best overall result. In 56L 55Hz tuning gives maximum SPL of 121dB at 62Hz, but only 104dB at 40Hz. 48Hz tuning still gives 118dB at 62Hz but with a much more useful 110dB at 40Hz.

[quote name='yorks5stringer' timestamp='1415011014' post='2595501'] How do you get on with the right hand drive and UK registration plates in New Hampshire..... ? [/quote]That's my spare that I keep garaged in St.Andrews, for when I visit to play a few rounds.