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Bill Fitzmaurice

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About Bill Fitzmaurice

  • Birthday 27/11/1949

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    New Hampshire, USA

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  1. That's possible, and you can't assume that any design was arrived at by scientific means. Marketing departments have a habit of specifying target dimensions, driver sizes and wattage ratings with little regard to how well it works, because they're interested in how it will sell. For instance, at one time the Kappa Pro Ten was a popular driver in 'boutique' cabs, mainly as its 500 watt rating could be advertised as a step up from the usual. However, it was designed for PA midbass/midrange, so with electric bass it worked no better than a 250w rated Beta 10 that cost and weighed half as much.
  2. Ideally, but it's not as critical as using the same drivers in very close to the same box volume per driver. That way you avoid the most common mish-mash mess, as typified by the 410/115. That combination by and large doesn't work as intended, as the 410 will usually have higher thermal and mechanical power capacity than the 115, when it needs to be the other way around.
  3. IME WinISD isn't buggy. It has some idiosyncrasies, but they're mainly related to user experience with the program. HornResp is considerably more sophisticated, but it gives the same results. As for the cab volume, remember to deduct for the space taken up by the port. Using two non-identical cabs is always a crap shoot, no matter what their configuration.
  4. True, but if he makes the cab smaller and tunes it to 62Hz, as opposed to leaving it as is tuned to 50-54Hz, he'd lose 4 to 5dB of sensitivity from 35 to 55Hz. I wouldn't want that myself.
  5. 'Best' is a relative term. It has maximally flat response in that size cabinet, but with weak low end. It won't be as flat in a larger box, but it will go lower. A smaller box with higher tuning would be appropriate for a PA top that's used along with subs, but not for an electric bass cab. There are none. For that matter in reflex boxes I don't use panel mounted ports, I use corner ports in all four corners. They work better than panel mounted ports, and they brace the cabinet baffle, top, bottom and sides as well.
  6. Put it on the back, or if that doesn't allow the necessary length put it on a side. It will sound the same no matter where you place it.
  7. 0.33 is too low for a sealed cab, but that alone isn't why it lacks bottom end. The high Fs along with being sealed is. Sealed cabs don't go low unless you load them with low Fs drivers, and then you trade off sensitivity. If I had to use it I'd use a 45 liter net cab tuned to 50Hz.
  8. They made it sealed because it had to be when that small. When using a driver that has specs suitable for either sealed or ported the ported will always be larger, not only to allow the port to fit inside, but also to allow tuning low enough to make porting worthwhile. That's the trade off to realize the lower extension and higher mechanical power handing that ported gives. While on the subject of mechanical power handling, check the excursion chart. There's no point in using a larger port area to keep port velocity down with more power than the driver can take before exceeding xmax. I won't say I'd be shocked if the SICA can take more than 50 watts, but I'd be surprised.
  9. Buy a set of plans and you can hire anyone you wish to do the build for you. Just don't let them do things their own way. Some of the worst results have come from contracted builders who should have stuck with making furniture, while some of the best have come from first time builders.
  10. The dip is where the distance from the rear of the cone to the front of the cone is 1/2 wavelength. To calculate that frequency divide the speed of sound by that distance, then divide by two. The speed of sound is 13,500 inches per second. It is unavoidable, and why the most popular iteration, the JBL 'Scoop', went away. About the only example of rear loaded folded horns still around are the Danley Sound Labs tapped horn subwoofers. They have the dip, but it occurs above their nominal 100Hz maximum pass band. When they first came out Danley published SPL charts, and the dip, between 120Hz and 180Hz depending on the model, was very obvious at around 12dB deep. Even though that was above the pass band it garnered lots of criticism from the usual wags. When that happened Danley fixed the problem...by cutting off the charts at 100Hz.
  11. I remember Arjank from the days when I still did talkbass. He was always pushing Oberton, as if they were something special. They're OK, but no better than a dozen other brands. The LaVoce WAF 153.00, for instance, is almost Identical, and sells for $160 with shipping. https://www.parts-express.com/LaVoce-WAF153.00-15-Woofer-8-Ohm-293-720 I wouldn't do a rear loaded folded horn. They have an unavoidable response dip where the front and rear waves meet with reverse polarity. That's one reason why they disappeared from the scene thirty years ago.
  12. It's impedance, and 6.5 ohms is the minimum, not the nominal. Assuming he wired them parallel the cab would be a nominal 4 ohms impedance. The Beyma SM212 is a very good driver, a considerable step up from the average.
  13. Vaccine wiped out smallpox and has almost wiped out polio. The problem is that virus is like whack a mole. Wipe out one and a new one comes along. The good news is that mRNA allows us to come up with new vaccines much faster than before. In the long run this experience might prove beneficial, as we may be able to use mRNA vaccines to target cancer.
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