| Re: Blow Fuse! [message #50573 is a reply to message #50571] |
Mon, 22 January 2007 16:35   |
dB
Messages: 234
Registered: May 2009
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Master |
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1. Place a RC damper for the woofer (between W+ and W-).
R= 7.6ohm (you can use 2 of those 15 ohm in parallel, or one 8 ohm, like the yellow ones you have)
C= 40uF (in series with R=7.6), you can use 33uF CAP and up close to 40/44uF (2x22uF in parallel).2. Disconect (take out) the power resistor (15ohm) you have for the tweeter/to ground (between T+ and T-), (the 15 ohm one that is in parallel with cap / leave) 3. Use a lamp of at least 7/8 ohm, you can use two lamps in series to duplicate the effect of a resistor, if you use the lamp that Wayne said. Measure the lamp with Meter to have as many lamps to make 7/8 ohm. The speaker at crossover point (-3dBs - 1600/1700 Hz) gives about 92dBs sharp, side of woofer and on the side of HF driver.
I think that's about it.
Best Regards
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| Re: Blow Fuse! (3) Non Inductive Resistors [message #50576 is a reply to message #50573] |
Mon, 22 January 2007 18:22 |
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Messages: 234
Registered: May 2009
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Master |
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When you ask for Power Resistors always specify NON INDUCTIVE. Metal-Mite®Aluminum Housed Axial Lead Wirewound, 5 watt to 50 watts
http://www.ohmite.com/cgi-bin/showpage.cgi?product=89_series Audio Gold Resistor Family, specifically designed for high-end loudspeaker, 3 watt to 50 watts
http://www.ohmite.com/cgi-bin/showpage.cgi?product=audiogold
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| Re: Blow Fuse! [message #50577 is a reply to message #50571] |
Mon, 22 January 2007 18:34 |
Chris R.
Messages: 82
Registered: May 2009
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Viscount |
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> Thing is the top end was lost as the lamps blew so I'm looking for a solution that is not quite so all or nothing. Turn the power down so the lamps don't light? If its not loud enough, get more horns an drivers, or bi-amp. Chris
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| Re: Blow Fuse! (2) Update! [message #50578 is a reply to message #50575] |
Mon, 22 January 2007 19:44 |
dB
Messages: 234
Registered: May 2009
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Master |
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BEYMA 15G40 700WEminence/PSD2002 - w.out10uF CAP for pseudo first order Hi,
Sory, of course you can leave the 10uF CAP out and you can play with that. If you have it on the bass the sound goes up a little. But you must have the RC damper for the woofer about this values, as I said before.
! RC damper for woofer
R=7.6
C=40uF You also want to have less resistor on the Lpad, so instead of the 15 ohm you should have a 8 ohm resistor with the 0.47 CAP. The sound goes up a little for the PSD2002.
! series/parallel Compensation components
R=8
C=0.47uF (Where you can play is on the lamp) You should have about a 6 ohm across, like a two bulbs in series to give a nice response like this.
Best Regards
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| Crossover Slopes [message #50581 is a reply to message #50578] |
Mon, 22 January 2007 21:23 |
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Wayne Parham
Messages: 18783
Registered: January 2001
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Illuminati (33rd Degree) |
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I always put a Zobel RC damper on any woofer that uses a passive crossover, second-order or higher. Sometimes, I'll run a midwoofer "wide open", or maybe with just a series coil. Of course, a woofer with a single series coil does not really have a first-order crossover since the load is not purely resistive. In fact, the woofer's voice coil is highly inductive, so a coil in series acts more like a voltage divider than a filter, making a sort of a shelved response. That's why I like to call them pseudo-first-order filters, to call attention to the fact that HF content is not attenuated with a 6dB/octave slope.On the tweeter circuit, I load the crossover with a higher impedance to make it slightly underdamped. This combined with top-octave compensation provides a couple octaves of flat response before HF augmentation begins. It does this by providing a tiny bit of peaking down near the crosover frequency. The net effect is a response curve that looks like shown below, which both pads the tweeter down to match the midwoofer and also compensates for the high-frequency rolloff of the compression horn. 
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| Re: Crossover Slopes [message #50582 is a reply to message #50581] |
Tue, 23 January 2007 08:25 |
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Messages: 234
Registered: May 2009
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Master |
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Thanks Wayne,
the Zobel RC damper makes it behave really nice with a slope maybe bigger than second order/12dB because of natural woofer fall-off after 2K.
Tuffer, with patience you will end up with a hell of a speaker.
Use filament light bulbs, not leds.
Best Regardshttp://www.amazon.com/3A-Racing-47-21122-Bulbs-211-2/dp/B00029J0JG http://www.donsbulbs.com/cgi-bin/r/b.pl/211-2%7C12.8v%7C0.97a~usa.html
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| Re: Blow Fuse! [message #50585 is a reply to message #50572] |
Tue, 23 January 2007 10:36 |
Tuffer
Messages: 6
Registered: May 2009
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Esquire |
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Thanks for all your help and advice guys. I am begining to think that perhaps I should consider bi-amping these boxes and only loaning them out with the associated amps/crossovers/limiters and my supervision. With the expense of all the crossover components, testing and possibilty of frying a few HF drivers I could have bought the other amp required. Should then be able to get the best out of the 15G40 driver also. I will put this one down to just a bit of feedback or a dropped mic and replace the fuses in the meantime. It seems like tweeter protection and passive crossover construction in general is a bit of a mine field. Without lots of equipment ,time , patience and know how it's down to luck if it sounds right. Perhaps that is why so few of the pro audio suppliers get their passive boxes sounding good!
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