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Old 4th August 2011, 05:28 PM   #2171
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Quote:
Originally Posted by Phaedras View Post
Is the cut-off at 2100hz because thats where the dip in the reponse is at? I was just wondering as the recommended cut-off for the PHT407n is 2000hz.. I guess the difference isnt immense

I take it you only mean 1 minidsp.. And that the miniDSP is a dual digital dsp because it has 4 channels?
Actually to accurately illustrate the transfer function of the tweeter filter and how it works you take the frequency response from winISD (PRO alpha version) of the s2010 woofer in the Boominator cabinet. That has a hump in the frequency response more or less equal to the pht407n tweeter if you just multiply all frequencies with exactly 20.

Now you add a high pass filter function in winISD. User SOS, fc=100Hz and Q=0.5 which is a 2nd order L-R filter. See how straight and smooth the response is now?

The crossover frequency is the frequency where the the output is -4.5dB for this filter because the total Q of the filter is between the drivers Q (0.66) and the filters Q (0.49). Actually the drivers Q is 0.42 but since there's a 4 ohm series resistor in series with the 2 paralleled drivers it changes to roughly 0.66. So the total Q for the filter is 0.57 which is a Bessel filter which crossover point lies at -4.5dB.

Similarly the woofers Q at the crossover frequency is also roughly 0.57, as the base Q is 0.31 plus the 0.06 added from the series resistance in the coil, and the Butterworth filter function has a Q of .71, which also gives a roughly 0.57 Q of the Bessel filter.

Yes, one miniDSP.
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Old 4th August 2011, 05:35 PM   #2172
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Quote:
Originally Posted by Saturnus View Post
Actually to accurately illustrate the transfer function of the tweeter filter and how it works you take the frequency response from winISD (PRO alpha version) of the s2010 woofer in the Boominator cabinet. That has a hump in the frequency response more or less equal to the pht407n tweeter if you just multiply all frequencies with exactly 20.

Now you add a high pass filter function in winISD. User SOS, fc=100Hz and Q=0.5 which is a 2nd order L-R filter. See how straight and smooth the response is now?

The crossover frequency is the frequency where the the output is -4.5dB for this filter because the total Q of the filter is between the drivers Q (0.66) and the filters Q (0.49). Actually the drivers Q is 0.42 but since there's a 4 ohm series resistor in series with the 2 paralleled drivers it changes to roughly 0.66. So the total Q for the filter is 0.57 which is a Bessel filter which crossover point lies at -4.5dB.

Similarly the woofers Q at the crossover frequency is also roughly 0.57, as the base Q is 0.31 plus the 0.06 added from the series resistance in the coil, and the Butterworth filter function has a Q of .71, which also gives a roughly 0.57 Q of the Bessel filter.

Yes, one miniDSP.
May I ask - Which book or books should one read to gain a complete understanding of concepts like those you are illustrating here?
Thanks!
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Old 4th August 2011, 05:43 PM   #2173
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Originally Posted by kristleifur View Post
May I ask - Which book or books should one read to gain a complete understanding of concepts like those you are illustrating here?
Thanks!
Vance Dickinson's Loudspeaker Cookbook is always a good start. The works of Thiele, Small, Bessel, Linkwitz, Butterworth and Riley are good seconds.
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Old 4th August 2011, 05:48 PM   #2174
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Originally Posted by Saturnus View Post
Vance Dickinson's Loudspeaker Cookbook is always a good start. The works of Thiele, Small, Bessel, Linkwitz, Butterworth and Riley are good seconds.
Exactly the kind of answer I was hoping for! Thanks.
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Old 5th August 2011, 12:22 PM   #2175
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Would it be possible to use the Eminence Beta 10 instead of the HP-10W? Should the cabinet be re-done and should I add a 0,65mH coil to dampen the peak at 2k?

If its not a good idea, what should I take? I need the parts before August the 16th and I dont have plans spending half a fortune on it.

Max
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Old 5th August 2011, 12:26 PM   #2176
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No, they're useless. Just buy the Goldwood GW-1058 instead.
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Old 5th August 2011, 01:45 PM   #2177
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I woke up this morning at 6 am and felt like spending some money. I went online and bought 4*S2010 at a total price of £264,45 including shipping and VAT.
When I came home from work and checked the status, they were dispatched from the shop and on their way.
Now there is no turning back, now I have to build what I have planned and it feels good.
Have a great weekend everybody.
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Old 5th August 2011, 01:55 PM   #2178
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Quote:
Originally Posted by Campino Morten View Post
I woke up this morning at 6 am and felt like spending some money. I went online and bought 4*S2010 at a total price of £264,45 including shipping and VAT.
When I came home from work and checked the status, they were dispatched from the shop and on their way.
Now there is no turning back, now I have to build what I have planned and it feels good.
Have a great weekend everybody.
Awesome Can't wait to hear more about it..

I'm planning on selling my current boominator some time during autumm and then hopefully be able to build a signature boominator with a few new ideas during winter/spring..

Edit: Btw, I found a belgian reseller with the pht407n in stock, if you still fancy buying some
http://www.bekafun.com/index.php?act...=&aantal=53946

Last edited by Phaedras; 5th August 2011 at 01:59 PM.
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Old 6th August 2011, 07:53 AM   #2179
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Originally Posted by Phaedras View Post
Awesome Can't wait to hear more about it..

I'm planning on selling my current boominator some time during autumm and then hopefully be able to build a signature boominator with a few new ideas during winter/spring..

Edit: Btw, I found a belgian reseller with the pht407n in stock, if you still fancy buying some
Bekafun
Thanks, I haven't decided which tweeters to use yet. As far as my audio understanding goes, the PHT-407N has a higher power handling, 2 more dB in SPL and will reduce the weight with a total of 2,8 kg. compared to the standard PHT-407 wich is not a neodymium but a ferrite magnet.
I can see from the SPL vs. FREQ diagrams that the 407 has a way higher output in the low range from 0,8-2,2 KHz. But I don't know if that matters since the cutoff frequency should be at 2 KHz accordingly to data-sheets.

Last year Saturnus wrote this about the PHT--407N, but I don't know if he has changed his mind, or if the different setup in this case makes the PHT-407N a better choice if we don't think about the money.

Quote:
"I'd recommend not using the N version. and instead get the much cheaper and much much better normal version. As it goes deeper, uses a phenolic diaphram that sounds a lot better, handles more power. Oh, and did I mention it's 2/3rds the price Click the image to open in full size."
Have anybody found a site or a store in Copenhagen where Charles Dickinson's Loudspeaker cookbook can be found?
I can only find people that recommend to buy it, but not where to do so.
I would love to learn some more about loudspeakers instead of asking Saturnus 5 stupid questions a day.

Last edited by Campino Morten; 6th August 2011 at 07:57 AM.
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Old 6th August 2011, 08:13 AM   #2180
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Yeah, I changed my mind about the N version after hearing it. It's better than I feared and basically the same as the normal version.

It's Vance Dickason. http://www.amazon.co.uk/Loudspeaker-...2618265&sr=8-2

Oh, and congrats on buy the s2010's

Last edited by Saturnus; 6th August 2011 at 08:17 AM.
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