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Bill Fitzmaurice

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Everything posted by Bill Fitzmaurice

  1. They don't provide adequate specs to draw a conclusion from, but I doubt they're going to do the job without subs at other than coffee house levels.
  2. Google 'Hoffman's Iron Law', though it should be something every bass player is very familiar with. If it's going to be small and it's going to go low then it can't have high sensitivity. One can get around low sensitivity with enough power, and premium drivers that can make use of it, but that removes 'budget' from the conversation.
  3. I've never used a pedal, never needed or wanted one. I had a raft of them when I played guitar, but with bass all the effects I needed were my hands.
  4. He used to do that, and a lot of other things with varying degrees of success, but he's been running a conventional Ampeg setup since at least 2011, when I last saw him.
  5. If this is just to make use of a box and a driver you have on hand without any expectation of a great result then use plywood per above. But otherwise I wouldn't do it unless loudspeaker modeling software reveals that the box and driver are a good match.
  6. I have no idea. It's not like Alex to create terms of out thin air. I'd ask him.
  7. Yes. There is no difference, a volt is a volt. The question is whether or not you need to bridge to realize enough voltage swing to get full output from the speaker. If you don't then there's nothing to be gained with bridging.
  8. Cone excursion. When impedance is halved excursion is doubled for a given voltage swing. When it's doubled excursion is halved for a given voltage swing. One cannot say x watts will result in y decibels, or that x watts will result in y millimeters of excursion. Those equations do not exist. One can say that x volts into z ohms will result in y decibels, or that x volts into z ohms will result in y millimeters of excursion.
  9. When you double the voltage swing into a speaker the cone excursion increase is the same as what occurs with four times the power. That's what leads to mechanical damage. Yes. You're not considering impedance. Engineers seldom look at power, we look at voltage and current, the former with respect to the capability of speakers, the latter with respect to the capability of amps. Power is an attempt to simplify the equation, but in truth it just further muddies things.
  10. Voltage swing is what determines cone excursion, which determines volume. Power is what you advertise to convince people to buy your product.
  11. This question comes up often enough on my forum that I added an FAQ reply: When should I bridge? The answer is almost never. Forget about the silly power ratings that manufacturers post for bridged output, that's just advertising piffle aimed at the unwashed masses. Bridging isn't about power, it's about voltage swing. You use it when your amp doesn't have enough voltage swing to drive the speaker to its displacement limit. Nine times out of ten that's because the speaker has a high impedance, say 16 ohms. The tenth time is when your amp is rated at less than a quarter the power output that your speaker is. If you do bridge when you don't need to the doubled voltage swing quadruples your chances of blowing drivers. Bridging into multiple cabs also can cause the amp to overheat, as bridging typically doubles the amp minimum load impedance, while using multiple cabs lowers the load impedance. Not likely. There may be tens with a thermal rating of 600 watts, but I'm not aware of any that will take more than half that before reaching their mechanical limit. Also, power amps are intended for PA use, where plenty of headroom is desirable. That's not necessarily the case with instrument amps.
  12. It's not what you meant, but clipping is clipping, no matter where it occurs in the signal chain. It can be bad for tweeters, that's why guitar cabs don't use them, but will never hurt a woofer. http://www.bcae1.com/2ltlpwr.htm
  13. That's the Myth of Underpowering, and it's just that, a myth. If amp clipping, or clipping anywhere in the signal chain, hurt woofers guitar players would be swapping them out at every break. Clipping is only potentially dangerous to tweeters, because the high frequency content is abnormally high. And we don't play sine waves.
  14. Farting out occurs when the combination of power and frequency attempts to force the cone to travel beyond its mechanical limits. The cure is to reduce the volume and/or low frequency EQ. The cab power rating doesn't indicate whether an amp can push the cone too far because that rating is thermal, not mechanical. Cone excursion goes up as frequency goes down, so a 500 watt signal may not cause over-excursion at 500Hz while a 50 watt signal at 50Hz may. The simple answer to farting out is that if one cab won't handle the combination of volume and bass EQ that you use you need two or more cabs, or one cab with more driver displacement. https://barefacedaudio.com/pages/how-speakers-move-air-volume-displacement
  15. No. Let's say the frequency is 100Hz. That means the cone must go from rest to full outward excursion to full inward excursion and back to rest 100 times per second. If it does so over a distance of, say, 6mm it must move six times faster than it does over a distance of 1mm. How cone velocity can affect the result is explained here: http://www.readresearch.co.uk/loudspeaker_papers/klipsch_modulation_distortion_article_1.pdf
  16. That's what Chris Squire did as well. I doubt he used a crossover. He probably just plugged into both. Most amps of that period had parallel input jacks, making it very easy to daisy chain amps.
  17. Xmax is the distance the cone can travel before distortion becomes severe. The longer the xmax the louder it can play. The best way to compare different drivers is with speaker modeling software. The program I use the most for sealed and ported cabs is WinISD 0.7. With it you can see the effects of the box size and tuning, and see Maximum SPL, which is determined by both the voice coil power limit and xmax.
  18. Neither of those are 200 watt, so I suspect those in the video are B102 or BP102. The magnet in the video also looks too large for the frame to be a twelve. It's true that one doesn't need a 32Hz F3 for low B, no more than does anyone need a 41Hz F3 for low E. But low B is still more demanding than low E, so I'd want at least 6mm xmax for low B use. 6mm xmax is usually going to cost more, but my philosophy is buy once, cry once.
  19. For -3dB at 40Hz would require an internal box volume of 300 liters, exclusive of the space taken up by the port and the drivers. You don't necessarily have to go that low, a 50Hz F3 from a net box volume of 200 liters would suffice. But with less than 200 liters the low end would fall off rapidly. There's also the matter of the 4.4mm driver xmax. That's adequate for the most part with a low E, but not with a low B.
  20. That's ported. Measuring frequency response is done with software, like HolmImpulse, and a USB measurement mic. The Beta 12 is an entry level driver, so whether it's adequate for your needs only you can say.
  21. With a proper balanced interconnection there's no need to lift the ground, that's one of the advantages of balanced. That said, not all devices are correctly configured. Have a look here, scroll to page 216. https://www.yumpu.com/en/document/read/25666510/ranenote-collection
  22. There's no point to bi-amping similar speakers. The difference in the low frequency limits would have to be close to two octaves to make it worthwhile.
  23. +1. One can be perfectly fine with a 30 watt Ampeg B-15. One thing you can be sure of with respect to watts: the more someone dwells on their importance the less they understand about amplification. They probably can't even recite Ohm's Law from memory.
  24. Assembled in the US from components sourced in Asia. That's not the same thing as made in the US, not that anything is, any more than is anything made in GB.
  25. Maybe. The problem when you use non-specific subjective terms is that there's no real definition, and therefore no agreement, on what it means. That greatly increases the difficulty of realizing whatever it is that you're trying to get.
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