Bill Fitzmaurice

[quote name='gilmour' post='127799' date='Jan 25 2008, 10:19 AM']All of the internal bracing is in (I didn;t take pics it's not very exciting, and with the screen on my camera not working it's also very difficult), except for the bracing over the rear acces panel, I realised that if I put this in then I won;t be able to fit the driver through the gaps.[/quote]
Right. The driver should fit through the opening on an angle, but it's a tight fit. I'll alter the plans specifying the opening size .

The bulk of the excess adhesive can be easily removed with a sharp chisel, using a planing action. Much faster than sanding.

[quote name='Jamesemt' post='124256' date='Jan 20 2008, 06:22 PM']They seem like a lot of money, but would go with my Superfly head.[/quote]
Mine works fine with a single 1x10, but my single 1x10 has 106dB sensitivity.
As far as conventional cabs go I'd be looking at a pair of 4 ohm 2x10s with neo drivers. Leave one at home when you don't need it. Can't say about the specific Ashdowns.

[quote name='tinyviking' post='123199' date='Jan 18 2008, 06:38 PM']I've been looking at BFM Omni's or perhaps another more standard 2x10 or 2x12 design as I've read on other forums a debate regarding wether or not the BFM bass horn style delivers any real advantages in smaller cabinets;[/quote]
Let me guess: on one side those who have never seen, let alone heard, one of my cabs, but know all the answers, beating down the opinions of those who do own them. You don't have to be an engineer to figure out which of those groups has the more informed opinion.
But as to the question, if one did horn load a woofer in a cabinet with the same net volume as the average commercial 1x10 it wouldn't work. Therefore, I don't.

[quote name='bigjohn' post='122908' date='Jan 18 2008, 10:17 AM']Hi Bill,

Do you think a cabinet of 21" wide, 35" high, 15" deep is big enough to get 2x15s in?

If I was to build one or have one made?

I think your website answers me there...

[url="http://www.billfitzmaurice.com/Omni10.html"]omni 10[/url] is 16"x20"x26

26" high, 20 wide, and 16" deep? Which should (just) fit in my boot?

Is a 2x12?

Is there any point me loading one of these with 2x200w 8ohm 12" and powering that with an svt3-pro?

Would that be "louder" than what I've got?[/quote]
Cabinet design is a far more complicated process than deciding on an arbitrary cabinet volume and then stuffing as many drivers as possible into it. Not that it isn't done that way, most commercial cabs are in fact, but it's not the right way. The best place to get specific answers vis-a-vis my cabs is on my forum.

[quote name='bigjohn' post='122806' date='Jan 18 2008, 07:55 AM']Running a 15" and a 2x10 would get full power from the amp -[/quote]'Getting full power from the amp' is by and large a wasted effort. If you double the amp's output you'll at best get an additional 3dB, which is audible, but just. Buggering up a combo will only make it valueless. If 150 watts into 1x15 isn't enough 300 watts into 2x15, or the equivalent thereof, is the minimum you need to make the change worthwhile. Either sell the combo and get a big rig or get the drummer the aforementioned smaller sticks, and perhaps a whack or two upside the head.

[quote name='dood' post='120298' date='Jan 14 2008, 01:23 PM']I suspect very few manuals include a schematic diagram of the amp. Though having said that.. it is *possible* to locate said schematics on the web instead.[/quote]
A schematic isn't a necessity per se, the main idea is to see if the manual specifies dual voltage operation. Most amps from at least the last decade are, as it's cheaper for the manufacturer to stock one transformer that will work either way rather than two.

[quote name='Subthumper' post='119800' date='Jan 13 2008, 04:49 PM']Why not contact the shop in the states where you want to buy it before you go and see if they can get a UK export model? Could save a lot of agro.
Cheers Just[/quote]
Or download a manual.

[quote name='Jack' post='119059' date='Jan 12 2008, 06:31 AM']Yup, head->cab 1->cab 2 is still parallel if thats what you mean.

I think the reason Eden have series on some of their cheaper combos is so a beginner can plug in ANY cab and not have to worry about impedance.[/quote]
More likely the internal driver(s) is already at the amp's minimum load rating to maximize output. For example, all the Nemisis save the 15 are 4 ohm rated with 4 ohm speakers.

A transformer capable of handling the power draw of an amp will require no less than the same VA rating as the transformer in the amp, so you might as well just replace that. Before doing so RTFM and be sure the amp doesn't have a dual primary that can be reconfigured for 240.

[quote name='Jack' post='118542' date='Jan 11 2008, 09:17 AM']I think Bill was more about 'ohmage' than 'resistance'.

Hey, at least youre aware of 'it', more than a lot of people.[/quote]
The problem with the quasi-word 'ohmage' is that it could refer to impedance, could refer to resistance, could refer to inductive or capacitive reactance. Being non-specific makes it useless in an engineering context, so while it does appear in the vernacular it is not used by the engineering community. Resistance is only used with respect to speakers in its context as a component of impedance.

Gentlemen, the term is [b]impedance[/b]. Bad enough that we butcher the Queen's English as badly as we do on our side of the pond with words concocted out of whole cloth.

[quote name='Hamster' post='117886' date='Jan 10 2008, 09:58 AM']Well don't keep us all in suspense Bill! - which one is best?

Hamster[/quote]
Fuschia.

[quote name='gilmour' post='117671' date='Jan 10 2008, 05:15 AM']Does that mean an SWR Redhead would go Faster? [/quote]
Laugh you may, but I recall many extended discussions between ostensibly intelligent human beings on a forum who debated ad nauseum over which color shrink wrap tubing on wire connections sounded better.

[quote name='Gray' post='117469' date='Jan 9 2008, 05:15 PM']Turbosound decided to use the 'turbo blue' paint colour on their cabinets because it sounded 'better' in blind listening tests...[/quote]Or they got a good price on a boatload of blue paint that no one else wanted.

[quote name='Gray' post='117184' date='Jan 9 2008, 12:22 PM']In PA world (particularly in regards to driving bins) its fairly standard practice to use amps which are twice the rated RMS output of the speakers they are driving (i.e. 1000 Watt RMS amp driving a 500 watt RMS cone).


Gray[/quote]In the instrument amp world the opposite is very often the case. With PA systems one does not wish to have distortion anywhere in the signal chain. With instruments distortion, sourced both within the amps and the speakers, is part and parcel of the instrument tone. Bass in general doesn't go to the extremes that guitar does in terms of the distortion density, but when a bass player refers to 'growl' in his tone distortion is the source.

[quote name='warwickhunt' post='117116' date='Jan 9 2008, 11:28 AM']no amount of charts and graphs can account for it![/quote]
Actually, they do. The problem is obtaining accurate data, or more to the point where the electric bass cab industry is concerned, any data.

[quote name='Crazykiwi' post='113533' date='Jan 4 2008, 08:57 AM']EBS rate their 212 at 103dB.[/quote]That would have to be a peak reading. There are no twelve inch drivers capable of that level broadband averaged. Twelves do exist that have 100dB sensitivity (making a pair 103dB), even a bit more, but they only achieve that sensitivity above 200 Hz or so. Below 100Hz, where it counts, 98dB is the practical limit in a direct radiator cabinet.

[quote name='Hamster' post='113329' date='Jan 3 2008, 08:51 PM']IIRC, it's twice as loud as a speaker of 103db sensitivity if using the same input level. I may be wrong, but I think I'm right. No doubt Bill F or Alex C will be along soon to put me right

Hamster[/quote]Close. A 3dB difference is equal to twice/half the power, but not twice/half the perceived volume. Hearing response is logarithmic, so it takes a 10dB difference to sound twice/half as loud.
As for manufacturers SPL ratings, they're next to useless, because they aren't referenced to frequency. Some, like Ampeg, quote a legitimate average figure. Some, like Eden, quote a peak figure. Some quote figures that defy all known laws of physics. None save Phil Jones provide the all important SPL charts that allow one to know the facts.

[quote name='jamjarjay' post='111271' date='Dec 30 2007, 08:50 PM']how can I tell I'm running too hard without damaging my head?

Thanks,

JJJ[/quote]
Clipping can't damage a head. But a clipped waveform greatly increases the high-frequency content of the signal, and that can lead to overpowering and possibly damaging tweeters. If you don't have tweeters don't worry about it.

[quote name='umph' post='110319' date='Dec 28 2007, 03:00 PM']if its ported you'd probly want the port on the floor so you get more low end. you can always put it in a corner to make it louder to.[/quote]
No difference. A port's output is roughly from 40 to 80 Hz, and is omnidirectional. If it's within less than a quarter wavelength of a boundary it gets boundary reinforcement. A quarter wavelength at 80 Hz is 3.5 feet.
[quote]There has been a tendency for some time now for hi-fi cabinets and multi-channel sound systems to follow this path. You don't see many cabs that don't try to keep a fairly narrow front face, making up internal volume with back to front depth as well as height. A narrow front face apparently helps to give a better stereo image when using two cabinets and helps the perceived location of sound in a room if using more than two in a multi-channel set-up. Even lateral dispersion is one of the factors affecting how well a pair of speakers create a believable stereo image.[/quote] That all has to do with diffraction, which is a different matter entirely.

[quote]Some say that rounding off the edges of cabinets helps as well, but whether this would have any useful purpose on a bass cab is debatable.[/quote]Also a diffraction issue, and less than about a 2 inch radius has little to no effect.

[quote name='bass_ferret' post='108993' date='Dec 24 2007, 12:13 PM']I wonder how this baby will sound?

[/quote]
On the technical side, it's a bass reflex cab, like 90% of the cabs on the maket, loaded with Eminence dirvers, like 90% of the cabs on the market. But it does have the drivers vertically aligned the way they should be, not horizontal like 90% of the cabs on the market, so it's a step in the right direction. If it only had a midrange driver instead of a tweeter, so there would not be a midrange 'hole' in the response, and if the box were actually large enough to allow the woofers to work as well as they could, I'd call it a proper design.

[quote name='Hamster' post='108895' date='Dec 24 2007, 07:51 AM']IIRC, the argument is that it's always best to stack speakers vertically. It improves the vertical dispersion - which I can get my head around, and for some reason it improves the wider dispersion - which I don't understand I'm trusting the opinion of someone like Bill Fitzmaurice or Alex Claber on this.

Hamster[/quote]Two reasons for vertical stacking. One, you can hear them better. Two, the audience can hear them better. That has to do with two other facts. First, the all important midrange frequencies travel in relatively straight lines. The further the speakers are below your ear level the more difficult it is to hear them. Second, the angles of dispersion are inversely proportional to the width and height of the source. A low wide source has narrow dispersion on the horizontal plane, wide dispersion on the vertical plane, and that's the precise opposite of what's desired. Wide horizontal dispersion, for the benefit of the audience, and narrow vertical dispersion, so as not to waste power scerenading spiders on the ceiling and mites on the floor, is what you want, and you get that from a source that is narrow and high.
[quote]TBH you aren't talking HUGE difference when you do this.[/quote] Not necessary with one 2x10, but two stacked on end one over the other is significantly different than two side by side on the floor. That's why side by side cluster PA systems are landfill bound, being replaced by tall line arrays. Bass cabs should be tall and narrow too, but technologically the electric bass cab industry lags the PA industry by at least a decade, if not two.

[quote name='TimmyC' post='108048' date='Dec 22 2007, 06:23 AM']I thought he used an Ampeg B15n for a lot too?[/quote]For monitoring, his recorded sound was taken direct.
The purpose of tweeters is to allow the full range of the bass to be reproduced. As noted previously the main defect usually lies in the implementation, not the device. Most bass cabs would be far better served using a midrange driver in lieu of or in addition to a tweeter, the main reason why they aren't is cost, pure and simple.

IMO combos are almost valueless. Where portability is concerned sticking the head and speaker in the same box just makes for a heavier box. Where sound is concerned, in the effort to keep the overall box size and weight manageable they're even worse than separates vis-a-vis using too small a cab for the drivers within. As for flexibility, I'd rather a separate head and well engineered cabs, using as many or as few cabs as the gig requires so that I'm neither lugging too much gear to a small gig nor under-gunned at a large one. The only combo I'd consider is for personal practice, where output and tone aren't a consideration.