Bill Fitzmaurice

[quote name='stingrayPete1977' timestamp='1322930982' post='1457467'] He didn't design it though did he? I would imagine the top brass from Gallien Krueger would be happy to drop in and compare penis sizes Bill, No offensive [/quote]Frankly I've never seen a cab from G-K that indicates they have professional acoustical engineers design their cabs. Eye candy all, IMO. if you want to learn about how cabs should be designed and what really matters beyond looks spend some time on the Barefaced Bass site, it will be time well spent.

[quote name='stingrayPete1977' timestamp='1322919145' post='1457284'] Better tell Flea then Bill........ [/quote]I looked up Flea in the AES members directory. Oddly enough his name isn't there, so chances are he knows no more about how speakers actually work than anyone else who has not studied acoustical engineering. I've been driving for 45 years, that hardly qualifies me to design an automobile. [quote]if both cabs are of a similar quality running off the same amp hence the same EQ settings then the 15 will be producing more of the lower frequencys than the 4x10 even if that 4x10 could handle more[/quote]That's only true if the 115 has lower response than the 410. In most cases they don't. And then there's the matter of driver displacement. As one goes lower displacement requirements go higher. The total displacement of the average 115 is 330cc, that of the average 410 500cc. If the 115 were to add anything meaningful it would need considerably higher displacement than the 410, not considerably less.

[quote name='Lozz196' timestamp='1322866922' post='1456954'] Well the industry standard always seems to favour the 115 at the bottom. I suppose this is due to the "higher" frequencies that come from the 410. [/quote]That's the prevailing notion, but it's incorrect. The average 410 goes no higher than the average 115, while the 115 has wider dispersion. For that matter the average 115 goes no lower than the average 410, so there's nothing to be gained by mixing the two. What is pertinent is that the average 410 will handle more power than the average 115, making the 115 the weak link in the chain. For that reason put the 115 on top, so that when it starts to strain you'll hear it, rather than the 410, and know that it's time to turn the amp down.

[quote name='Ghost_Bass' timestamp='1322840846' post='1456558'] The Genz sounded very thin when standing on front of it but behind (in front of the ports) you could hear all the bass comming out, [/quote]Of course, because the mids and highs coming off the cones are directional. You didn't hear more bass standing behind the cab, you heard less mids and highs, which subjectively is the same thing. The difference in comparison with the Fender cabs has to do with a number of factors, port location isn't one of them. [quote]Sometimes i can't leave the cabinet near a wall to benifit from the reflex, in some places i had to play with my rig on my side, facing me [/quote]The cab doesn't need to be near a wall to benefit from reflex, again the port works in exactly the same fashion unless the cab is so tight to a wall as to upset the cab tuning. The cab does have to be close to a wall to gain boundary reinforcement, but that applies to all frequencies below the baffle step frequency of the cab, not just port radiation. The baffle step frequency of the average cab is 300Hz. Port radiation tends to be centered around 45-55Hz.

[quote name='Ghost_Bass' timestamp='1322830564' post='1456364'] I trust the opinions given above but i had rear and front ported cabs and i feel more bass if i'm using a front ported cab. The front port also helps the drum mics not to capture much of the bass... this is from my experience. If you place a rear ported cab next to a wall you'll get a bit more of the bass reflex but that just made my drummer complaint that he coudn't hear a defined bass sound, just boom... [/quote]You'll feel air flow more with the front port location, but that's not the same as hearing more bass. As noted port radiation is omni-directional, the actual dB level is identical no matter where it's placed. You can get some interactions with a rear port and a rear wall, but those tend to be easy to fix, just pull the cab out another inch or two. If anything putting the cab a bit too close to the wall will reduce boom, not increase it, as it lowers the cab tuning frequency. Putting it tight to the wall can upset things, but again it's an easy fix, don't put it tight to the wall. As to why they're sometimes placed on the rear, usually because the cab size is too small to fit them on the front.

[quote name='fatback' timestamp='1322763158' post='1455625'] Thanks, Bill. The cab on stand is chest height, so not so far off 5 feet. Do you lose midbass at lesser elevations? [/quote]Yes. There's actually a cancellation notch where the difference between the distance from the speaker to the bass and the reflected wave off the floor to the bass is 1/2 wavelength. You can vary the frequency of that notch by both speaker and instrument placement, IMO rotating a knob is far more practical.

[quote name='fatback' timestamp='1322743247' post='1455141'] Alex, is the Midget especially dependent on boundary reinforcement because of its small size (probably a dumb question, I know)? [/quote]No more than any other cab, as all react to boundaries in the same fashion. To be accurate, you aren't losing lows with the cab elevated. That would require lifting it at least 5 feet off the ground. You're reducing boundary loading in the midbass. Using a parametric EQ to notch out the feedback, rather than lifting the cab, would have the benefit of giving additional headroom in the amp and speaker, as it reduces the amp output in the notched bandwidth. It would also give you a bigger bottom, as being able to dial in the precise frequency, notch width and amount of gain reduction will stop the feedback with minimal effect on other frequencies.

[quote name='aidanhallbass' timestamp='1322731923' post='1454912'] I will be looking to put my hartke LH1000 head on two HX410 1000w cabs How is the best way to cable them up? The options I think are, 1. head to top cab using channel A and bottom cab using channel B (which is how i've done it befroe) Or 2. Out from head using Speakon to top cab, then out from top cab to bottom cab, or 3. out from head channel A to top cab (1/4 jack) to top cab then top cab out to bottom cab.. Any wrong way or right way? What power would be used? 8ohm 4ohm?? [/quote]Option 1, one cab per channel. There's no advantage to the others.

[quote name='bremen' timestamp='1322568264' post='1452674'] A solid state amp will specify a minimum load impedance. Anything above this (up to and including no load) will be fine. [/quote]Conversely a tube amp tap impedance is the maximum load, you may go lower. And you can't run tubes with no load, but you can run them in to a dead short. In both cases what matters is the output stage, not the pre-amp.

[quote name='icastle' timestamp='1322425408' post='1450773'] Did you [b]really[/b] just write that? Anyone who's incapable of plugging something into the mains is certainly working in the wrong industry and the 'interconnect' is no harder than it is running a DI out from an amp back to a mixing desk. [/quote]When one uses interconnected pieces of gear independently powered the potential for ground loop noise rises exponentially with the number of devices employed. And if all your kit is in one box you don't have to contend with issues of bad or disconnected cables. If the OP was really comfortable with a complicated system I doubt he'd be as pleased as he is with what he currently has.

The problem isn't the piezos, its the implementation. But as noted already switching to a compression driver probably won't help. If you find a tweeter harsh you should consider switching to a cab that uses a midrange driver rather than a tweeter. IMO going directly from a woofer to a tweeter with a 4 to 5kHz crossover is a silly idea on the face of it, and is only done because it costs the manufacturer less than half what it does to cross to a midrange driver an octave or more lower.

[quote name='Walker' timestamp='1322417476' post='1450622'] Thanks Bill, assuming I would need to look at the max output of any mixer and not exeed the 250 wpc? [/quote]No, because said speakers probably can't handle more than 100w before distorting anyway. If they distort you turn it down, which I imagine is what you do currently. Having extra power on tap is never a bad thing, used judiciously. With a speaker rated 250w you're pretty safe running an amp rated anywhere between 125w and 500w. The same applies to electric bass amps and cabs.

[quote name='Walker' timestamp='1322413710' post='1450545'] So if I went for a powered mixer, could I still use the passive speakers I have? [url="http://uk.yamaha.com/en/products/proaudio/pa_systems/stagepas_500/?mode=series#tab=feature"]http://uk.yamaha.com...ies#tab=feature[/url] [/quote]Yes.

[quote name='icastle' timestamp='1322403470' post='1450370'] What complexity? All we do is feed the drum mics into the little mixer, balance everything on that and set up EQ - we then feed that signal into the main desk on a single channel that we just leave set flat. [/quote]You now have two pieces of kit rather than one, and the need to interconnect the two and connect both to the mains AC. And you have to buy the auxiliary mixer, so it's not like this happens with no cost. I'd put the money towards a better mixer instead, especially considering how much better the 212s is, with better channel EQ, two graphic EQs and effects, and how little the 212s costs.

All the added complexity of a sub-mixer isn't worth the trouble, Sell the mixer and get a Yammy EMX212s, which is a far better mixer as well.

[quote name='Musky' timestamp='1322092861' post='1446558'] Don't Celestion use a different way of measuring Xmax to most other manufacturers? I seem to recall some discussion that multiplying by something like 1.7* gives a figure that could be compared directly to an Eminence driver for instance. *Might be wildly wrong! [/quote]Eminence use Klippel Analysis, which is more accurate than plate minus coil. But at best the Celestion figure might go up by 20% with a Klippel figure, so that 2mm might go up to 2.4mm.

[quote name='Moos3h' timestamp='1321973822' post='1444975'] 2mm Xmax? Isn't that practically useless then? [/quote]If you want a highly compressed bottom thin tone or your only running 30 watts I guess it's OK. The BN15 400X is good at 4mm, though the .59 Qts of both it and the BL15 400 is a bit dodgy,

[quote name='alanbass1' timestamp='1321950384' post='1444621'] Is this a real bargain at £82 [/quote]Have you modeled it ? With only 2mm xmax I'm not sure it would be a 'bargain' at any price. The BL15-400 is infinitely better.

[quote name='NJE' timestamp='1321951334' post='1444642'] drummer/engineer [/quote]Oh, now I see where the problem lies.

[quote name='NJE' timestamp='1321872671' post='1443810'] The issue basically was that the front of house sound from my MarkBass was shocking and I put this down to the fact that the DI is only post EQ and the EQ was set up for me onstage. [/quote]Moot. The sound through the PA will be totally different than that on stage whether the DI is pre or post, because PA speakers are relatively flat in response, while bass speakers are anything but. The soundman should have had no trouble dealing with that, assuming the console had EQ on every channel strip. All he had to do was cut the lows and highs and boost the mids, the same as what your speaker does, to compensate for the EQ added to the signal. If he was sent a non-EQ'd signal he'd still have had to EQ the channel to get the PA feed to sound the same, or at least reasonably close, to the stage sound.

[quote name='51m0n' timestamp='1320450583' post='1427195'] You havent seen how small his back yard was [/quote] Road trip. Go to the nearest open field, all the required gear can be battery powered, including amplifier. [quote]Can't you just map the frequency response of a room? Not exactly simple but it's not rocket science either, just time consuming. Then it's a constant for all future tests? [/quote]In theory yes, but practically speaking, no. To measure in room at the required distances would be a sonic nightmare. There are methods to measure near field in room, but I don't place much faith in them myself.

[quote name='51m0n' timestamp='1320423838' post='1426762'] Yeah true, I've had long chats with Alex about the lengths he has to go to when measuring his cabs to get some idea of their frequency response - not a trivial undertaking at all! [/quote] It's actually easy if you have the right gear, and an open space to do the job. You measure ground plane, the mic literally an inch off the ground, for a half-space result below the baffle step frequency. Then you put the cab on its back and suspend the mic above it to get a half-space result above the baffle step. Splice the two together and you're done. If you want to do off-axis you do that with the cab on its back only, as below the baffle step axial and off-axis are the same. The gear used to be silly expensive, but today the software is free, and the hardware is less than a hundred dollars here. You can do the entire job, including off-axis plots, in about fifteen minutes.

[quote name='51m0n' timestamp='1320418058' post='1426658'] If so is it not possible that a combination of phase and off axis rejection from the mic would cause the mic to be significantly less bassy when micing from a couple of inches off the cone? Especially a cone a long way from the port? [/quote]Anything's possible, as every scenario is different. That's why definitive cab measurements are made outdoors (assuming you don't have an anechoic chamber handy) with the mic at least two meters, preferably more, from the cab.

[quote name='51m0n' timestamp='1320416219' post='1426620'] I'd beg to differ here Bill. If you close mic a couple of inches off the speaker you get none of the benfit of the cab port producing the low end. So by close micing you tend to take at least some aspect of the cab out of the equation as well as the room. [/quote] At a couple of inches off the driver the difference would be minimal; remember that port output is omni-directional. And there's also baffle proximity effect, which enhances the low end. True close micing to separate the driver and port outputs is done from more like a half-inch away.

[quote name='211dave112' timestamp='1320391937' post='1426146'] Is the sound that you get the sound of your cab or, as you're mic'ing the speaker, is it the sound of the speaker? [/quote]The two are inseparable. The point of close micing is to take the room out of the equation.