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DevilDriver

SSA Tech Team
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DevilDriver last won the day on January 1 2010

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About DevilDriver

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    Now let's re-define what it is you know
  • Birthday 04/06/1986

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    Regina, Sask, Canada
  1. CD vs mp3 Here's a comparison of the various LAME settings. I use v0 or v2 for anything lossy (the majority of my collection is in FLAC). You see that v0 is quite a bit smaller than 320kbps CBR but about as good.
  2. W7 vs XCON

    The W7 is not always the best value but is always one of the top performers, surviving a decade filled with subwoofers designed to knock it off its perch. I've never used an Xcon but I'd never turn down a W7 at a price I could afford. Just because a product is mainstream doesn't mean it is any less deserving. Buy the best product that fits your budget.
  3. Why is salvia not illegal?

    Bottom line is that the prohibition of something so physiologically harmless would just add to the business of the violent black market that prohibition has already created. It's also a question of liberty.
  4. Adire Brahma and USD audio

    Don't pay $400 for it. You can find Brahma's for less on caraudio.com, or you can buy similar products from Exodus Audio or Creative Sound Solutions.
  5. SPL vs SQ vs Daily, motor/suspension cooling the works

    Having a large magnet means you have a lot of potential flux in the system. You must have enough steel to carry the flux while still making sure the steel is saturated (ie. can't carry any more flux). Air has greater reluctance (resistance to carrying flux) than steel, so keeping the gap tight ensures you have the most flux possible in the gap (since the coil is closer to the steel). Any time you're able to increase BL, you're able to increase efficiency. There is no strong correlation between the amount of magnetic material in the motor and the power handling of the driver (note that talking about power handling and cooling is essentially the same thing). The steel in the motor does play a role, but the dominant factor is always the coil. The goal is to get the heat off the coil; in the past, the idea has been to get as much air moving in the motor as possible, which is, in part, one of the reasons the pole vent has been used. In reality, we just need to get the heat off the coil, so moving it anywhere else will be useful. So instead, you have a lot of steel in the motor, add some copper or aluminum shorting rings, and design the motor such that air is drawn down into the top plate, over the windings, and then passing the heat into the shorting rings below the gap or into the steel above the gap. The pole vent is still useful for relieving pressure under the dustcap, but it is best to keep as much steel as possible, in my opinion. Keep in mind that another dominant factor in efficiency is the mass that is being moved (Mms). The longer the coil, the greater the inductance. Since the inductance and resistance of the coil acts as a first-order (6 dB/octave) low-pass filter, it is preferable to have inductance that pushes the corner frequency (at which response begins to roll-off) above the bandwidth in which you'll be using the subwoofer. For SPL, you typically want a lot of windings in the gap (for both power handling and BL), so inductance is often higher.
  6. Woofer Speed

    x = x0 + vt x = 4" x0 = 0" t = 1 second/30 cycles = 1s/60 Solve for v. I divide the time by 60 as there are two 4" movements per cycle; as an alternative, you could set x to 8" and leave t as 1s/30 cycles. As I've mentioned several times, Le is the dominant aspect of transient response, while Mms (and other factors) play a lesser role. Note that there is a relationship between the time domain and the frequency domain.
  7. DXB-01 EarbuDD's

    Can I ask you guys why you bought DD buds and not someone else?
  8. Quad Stacked Magnet

    I think the point is mostly that the number of slugs is irrelevant. We can take about how tall the stack is or how wide, but using the number of slugs stacked tells us nothing at all. The most important thing about the magnets is that they saturate the steel with flux. You can use stacked magnets to gain more clearance (which is easier from a production standpoint), but all that really matters is that the magnets saturate the steel that your project requires.
  9. FI vs DD

    Id like you to buy the AQ2200 and do an actual comparison with the BXI 2607. Someone needs to do this atleast. What about a drop in comparison between 9500s and BTLs. I say that needs to be done before anything can be said. And which one of DD's fart cannons are you going to compare with the Fi Q since the thread is comparing the two companies? Has DD ever made a SQ orientated sub? 9100's are supposed to be (underhung), but there is no evidence to confirm that they are.
  10. Basically, his point was this: Speakers are highly inefficient. A moving speaker generates back EMF. The counter-voltage that is induced (back EMF) subtracts from the voltage supplied to the windings. Now because of how inefficient a speaker is, the suggestion is that the counter-EMF is especially problematic with low current inputs. This is, to an extent, true, but you must remember that at high-outputs we also lose output from non-linearity and thermal power compression. To be clear, I don't believe in this fallacy of "it requires X amount of power to get moving", and will not until someone shows evidence to the contrary. I have seen several measurements of a particular speaker's response vs frequency vs amplitude where output doubled with every doubling of power up to about 400 watts, after which the increase became increasingly small. If your theory were to be true, I would expect to gain maybe 1-2 dB for the first few doublings, then closer to 3 dB, then falling off again after that, which I simply have not seen. Further, it is an inductance-related problem (though not necessarily solvable with what we're doing now). More on this a bit later.
  11. XXX Components xover question

    Are the mids the newer ones with Split Coil topology, or the older XBL^2 drivers? Either way, you'll be limited to the 1.7-2.0 kHz region on the mids. Where you cross the tweeters over will depend on where you position them and level differences. You will likely have to scale back the power on the tweeters a bit, both for safety and a smooth crossover. You'll probably have to underlap a bit.
  12. watts vs. true watts

    So you are saying that folks who hear differences in various amplifier topologies, have either bad hearing or not very smart? What I'm saying is that ACTUAL differences between amplifiers are completely quantifiable...there is no magic pixie dust. Now, in terms of interpreted differences, I am saying that our ears and brain are not very smart. We have very poor memory for sound, and are unable to distinguish what is actually driving a difference between a variety of physical properties. We don't hear what happens with each component in the chain separately...we hear their summation. Even then, we are often unable to determine when a change is favourable or unfavourable (if the goal is accurate reproduction): instead, we hear how it relates to a personal preference. This is, of course, ignoring the whole philosophical argument of perception. We can only understand and compare against what we already know...what we've already perceived. No person here has ever heard a system that was a perfect reproduction of a song, and it is doubtful that we were there for the original production of our recordings; as such, it is impossible to state with a high degree of certainty using only our ears what level of accurate reproduction the system is achieving.
  13. watts vs. true watts

    Tell me more. I haven't met anyone with a complaint about them... Well for starters, the RF T15k gained CEA compliance even though it doesn't do near the continuous power it is rated for.
  14. Havoc: sealed vrs ported

    Just wondering what you meant by this statement. I have been finding a ton of drivers I have been using lately sealed, will not get above 63hz. I need something that will get to around 72hz. Is this possible with the Havoc? Also, I think I have asked this before, but do you know the Le? Keep in mind....the enclosure behaves as a highpass filter; with both sealed and bass reflex (ported) systems, the enclosure only has an effect on low frequency performance. If you are having a perceived problem with upper frequency performance, you need to address the vehicle acoustics by eq'ing down the bottom end or by selecting a driver with less inductance and inductance variation.
  15. watts vs. true watts

    I'm not completely sure I understand what the guy you spoke with is talking about. Can you get him to expand on it a bit? No, not all amps sound the same. Mind you, all amps that measure the same (whether that is by default or as a result of modification) will amplify the signal in the same way, and thus will often sound the same. The "sound" argument is greatly confused by our rather imperfect ears or, more specifically, our rather imperfect brains. Note also that there is no such thing as "RMS" watts. RMS current, yes....RMS voltage, sure. But what we're really talking about is average power....average watts.
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