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Everything posted by Bill Fitzmaurice
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Genzler 210 array stacked vertical??
Bill Fitzmaurice replied to Chopthebass's topic in Amps and Cabs
What matters is the positioning of the tweeters, not the woofers, so you'd stack them as shown in the picture. -
Warning.... Kappalite 3015 NOT designed for Bass!
Bill Fitzmaurice replied to skidder652003's topic in Amps and Cabs
What sold me on my BMW 328 GT was room for my golf clubs and my gear, along with rear seat room for adults, with no compromising of performance. -
Vertically Oriented 2x10 Cab - Front Ported?
Bill Fitzmaurice replied to acidbass's topic in Amps and Cabs
How many of those tests involved measuring the results? The mere fact that you knew the cabs were front or rear ported would have influenced your perception. http://seanolive.blogspot.com/2009/04/dishonesty-of-sighted-audio-product.html -
What matters is the cab internal volume, not the specific dimensions. As to damping it's required on all the internal surfaces.
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Vertically Oriented 2x10 Cab - Front Ported?
Bill Fitzmaurice replied to acidbass's topic in Amps and Cabs
It does, but it doesn't matter. Low frequency projection is 360 degrees. That means rear ports project as much sound to the front as they do the back. By the same token front ports, and for that matter the cone, project as much sound to the back as they do the front. Dispersion only narrows to 180 degrees when the baffle width is one wavelength. At 100Hz that's 3.4 meters. At 50Hz it's 6.8 meters. -
Consumers are as much to blame as marketeers in that. You can see examples of that with every post where someone comments about 'getting all the watts out of my amp'. Being professional musicians we should all have at least a rudimentary understanding of how the tools of our trade work, but sadly most do not. That could be excused when all we had to go by was manufacturer sales brochures, but that hasn't been the case for the last two decades. The truth is out there, a simple search will find it.
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Warning.... Kappalite 3015 NOT designed for Bass!
Bill Fitzmaurice replied to skidder652003's topic in Amps and Cabs
Yes, you may, assuming you've used speaker modeling software to make sure it's compatible with the cab you intend to use it in and will handle the power you intend to use, both thermally and mechanically. The OP did not do so, resulting in his unfortunate experience. -
Egg boxes didn't absorb sound, they were used in radio stations and recording studios as diffusion devices. By scattering reflected sound waves they greatly reduced reverb and echo compared to flat surfaces. The shape became associated with improving acoustics, so when acoustical foam came along that shape was adopted. But foam lacks the density required to be an effective diffuser, so from that standpoint there's no advantage to the shape. Foam does absorb sound, with the rate of absorption and frequency to which it does so determined by its depth. Since the depth of the foam is less in the dimples it's less effective than foam with no dimples.
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While on the topic most commercial acoustical foam is convoluted or pyramidal. That doesn't do a thing, it just looks like it will.
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Which I alluded to previously. Most guitar drivers have very short xmax, so they'll go into high THD at low volume. Bass players may still want high THD, but not at low volume. Nonetheless most of us wouldn't want the other end of the spectrum, drivers with no midrange bump, typical of PA woofers. This Eminence 2512 strives for response similar to vintage drivers, but with much higher output, as opposed to the B&C 12NDL 76, which doesn't peak in the mids 10dB higher than in the midbass.
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Ouch. Cabs should be fully lined, with foam or polyester batting, 25 to 50mm thick. Mattress topper foam is inexpensive, as is furniture upholstery batting. Don't bother with materials advertised for speaker cabs, they're more expensive but don't work any better. Adhere it with spray glue.
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Noisy headphones on Ashdown RM 500 evo II
Bill Fitzmaurice replied to Mickyk's topic in Amps and Cabs
Nope. Buzzing may indicate bad transducers, or it could be buzzing at frequencies too high to hear through the speaker. -
Not Eminence, for one. Back in the day there were no bass drivers, just musical instrument drivers. Bass and guitar cabs were loaded with the same drivers, so they both had similar coloration. As technology progressed bass drivers were made with lower resonance and longer excursion to better suit bass, but in order to preserve the midrange tone Eminence in particular maintained to the extent possible with the lower Fs and longer xmax a similar rising response in the mids, even with the advent of neo. LaVoce, a relative newcomer, has taken that philosophy to heart, with response very similar to Eminence in their bass drivers, which is a departure for a European company.
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There are tonal nuances, especially those created by the speakers which include mechanical power compression, cone break up and THD, which can't be duplicated using a DI. If you want what's in the PA to come close to what's coming out of your rig only a mic will do. That doesn't mean the guy in the FOH can't screw it up anyway, but at least you've got chance of his getting it right.
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Sub woofers - sublime or ridiculous?
Bill Fitzmaurice replied to Al Krow's topic in PA set up and use
It's probably not as little as it seems to be. A look at an equal loudness chart reveals why. If the system is at 100dB at 500Hz, where our hearing is most sensitive, it has to be at 110dB at 50Hz to sound flat. That's a 10x power difference between the subs and the mains. Even when flat the mains should always sound louder than the subs, because our perception of loudness lies in the mids, not the lows. If you turn off the mains the subs shouldn't sound as loud as the mains. If they do they're too loud. The presence of subs shouldn't be obvious. What should be obvious is what happens when you turn the subs off. In that case the subs aren't loud enough. Pretty much all recordings since 1990 were mixed using subs in the studio, so if switching off the subs makes no difference you're not hearing what's on the recording. To that end the better FOH guys will take two RTAs when setting up the system. One will be that of their preferred reference recording, taken at the channel strip, to see the frequency content of the recording. The other will be that of the system. They'll adjust the system EQ to approximate as closely as possible the source frequency content while compensating for the room response. -
The top chart is the modeled response of a typical twelve loaded cab, but it's not accurate above 200Hz or so. That's because modeling software uses Thiele-Small specs, which are only accurate to 2 octaves or so above the driver resonant frquency, in this case around 50Hz. A measured response chart would show the sensitivity increasing above 200Hz, with useful (-10dB) response to at least 3kHz. You shouldn't run this speaker much below 40Hz, as while sensitivity is dropping excursion is rising. Amp designers usually put in a high pass filter for this reason. Mine doesn't, but it does have full EQ. I pull the 32Hz slider all the way down.
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Yes, the port output shifts 180 degrees below the port tuning frequency, so the combined result of the port plus cone output falls at twice the rate of the port or cone output alone. That's the downside of a ported enclosure. However, compared to a sealed enclosure it still has higher sensitivity to at least an octave lower than sealed, along with far lower excursion.
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Sub woofers - sublime or ridiculous?
Bill Fitzmaurice replied to Al Krow's topic in PA set up and use
That means the tops aren't near their limit. At some point they'd be able to go significantly louder than one sub, unless it was loaded with an eighteen. -
Sub woofers - sublime or ridiculous?
Bill Fitzmaurice replied to Al Krow's topic in PA set up and use
The bad news is to keep up with your RCF tops you'd need at the minimum a pair of 15" subs, especially outdoors. The laws of acoustics will not be denied. -
Sub woofers - sublime or ridiculous?
Bill Fitzmaurice replied to Al Krow's topic in PA set up and use
You don't want to go to 140Hz, that gets into the directionally locatable frequencies, which limits placement options. 80 to 100Hz is the preferred range. -
Sub woofers - sublime or ridiculous?
Bill Fitzmaurice replied to Al Krow's topic in PA set up and use
Subs don't deliver watts, they deliver decibels. There's no direct correlation between the two. There is a direct correlation between cabinet size and driver displacement and how low and loud a sub will go. The larger size of the TS indicates it would probably go lower, the larger voice coil indicates it might go louder, but since there is no measured SPL chart or driver displacement shown there's no way to make an accurate objective comparison. As to one 12" sub being adequate it probably would be if the mains are 8", but that's about it. The mains are the tip of the iceberg you can see above the water. The subs are that part that's underwater. They need to be at least twice the size and cone displacement as the mains.