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Old 11th January 2013, 02:46 AM   #1
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Default Supplementary NEO3 crossover

Hi, I'm looking to experiment with supplementing the HF range on my electrostatic KLH Nine speakers. I have a pair of BG Neo3w tweeters I'm planning to use as they're lying around. The issue/question at hand is, since these tweeters are vastly different in their power requirements, compared to electrostatic panels, I'll need to power them directly from my amps (Ncores). My question is, does anyone have a suggestion for a simple crossover that I can use for this application. Ballpark values would be much appreciated for ideally a single capacitor and resistor. Thank you in advance to those who can help.
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Old 11th January 2013, 03:12 AM   #2
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what frequency do you want to cross them over at?
what's the difference in efficiency between the electrostatics & the Neo3Ws?
do you have a link to the BG's impedance graph?
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 11th January 2013, 05:26 AM   #3
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Here's a data sheet for Neo3 tweeters which are similar to mine: http://www.k4revenge.com/Mat/new/bgneo3pdr.pdf

The efficiency difference is about 10db. I'll be using the existing electrostatic tweeters with these so crossing over low isn't something I'm considering. I'm thinking around 3000hz but would like to experiment a bit to see if they improve with a higher crossover frequency. I'm also considering a cheap active crossover like a DCX as another alternative. Would this be worthwhile for my application do you think? It's of interest as I'd like to mess around with using a low-pass filter to around 16khz for the main speakers, and set up the NEO3 cover upper ranges.
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Old 11th January 2013, 09:23 PM   #4
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this may be useful:Zaph|Audio
looks like a really good tweeter, I've never used this type before, but i think I'd be inclined to crossover reasonably high, say 4KHz or higher, 2nd order.
With such a difference in efficiency, I'd use a proper L-pad rather than a single resistor
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 11th January 2013, 09:32 PM   #5
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some numbers- Lpad - 2.7 ohms in series, 1.8 in parallel
3KHz - 6.6uF, .42mH
4KHz - 5uF, .32mH
5KHZ - 4uF, .25mH
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 15th January 2013, 02:31 AM   #6
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Hi pete, could you elaborate on the Lpad bit of this. Are you suggesting two 2.7 resistors in series and a capacitor following would suffice for what I'm trying to do? I'm not doubting this however it's new territory for me so I'm hoping to better understand what you're saying before turning things on. Furthermore, if I were to go with an active crossover, which I don't really want to do as it seems unnecessary, what's the proper way to wire from a balanced termination on the XO device to a pair of speaker terminals on the drivers?
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Old 15th January 2013, 03:00 AM   #7
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no, 2.7 in series with the tweeter, & 1.8 in parallel with it:
L pad calculator - attenuation dB damping impedance decibel loudspeaker speaker voltage divider - sengpielaudio Sengpiel Berlin
re: "and a capacitor following would suffice " - no, that's first order,
I'd go 2nd order(for better protection for the tweeter), i.e a cap in series and an inductor in parallel
Crossover Design Calculators
( crossover, Then L-Pad, then tweeter)
active crossovers come before the amplifier: BiAmp (Bi-Amplification - Not Quite Magic, But Close) - Part 1
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency

Last edited by PeteMcK; 15th January 2013 at 03:20 AM.
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Old 18th January 2013, 01:06 AM   #8
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Thank you for the help. It's making things a bit more tangible. In looking at the calculator you sent, I assume Linkwitz-Riley is the crossover you're suggesting, in which case, the Ohm values would be 4 for highpass (my tweeter) and 16 for lowpass (the speakers). Hopefully you can confirm that I'm on the right track before I make a mess.
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Old 18th January 2013, 06:47 PM   #9
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Yes, L-R is what I used & 4 ohms for the highpass. - The lowpass section doesn't matter, 'cause you aren't going to use that, right?
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 11th February 2014, 12:10 AM   #10
satx is offline satx  United States
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Hi,

I didn't run any numbers for what you're trying to do, but 1R8 in parallel sounds very low. I would be more inclined to use a larger series and parallel resistor. The series resistor converts the power to heat and the parallel resistor allows the power to go to ground, the amount of power that returns to ground instead of flowing to the tweeter is dependant on the size of the resistor, ie larger parallel resistor= more power to tweeter. That is why you would also need to increase the series resistor's value to get the same attenuation as the PeteMck's calculator is solving for.

Sorry if that's confusing. My point is that with a parallel resistor of only 1R8 is likely to create a very low impedance for your amp. You are connecting a tweeter with an impedance of 3.5 ohms in parallel (I assume) with your stats which are also 4 ohms? In theory this will create a total impedance of 1.86 ohms at the crossover. That 1R8 parallel resistor could push this down well under 1 ohm.

I would agree that you should probably use a second order filter unless you are crossing >10K. If you are thinking of crossing the Neo3 around 2K then you will probably want to consider 3rd or 4th order filters.

Hope this helps,
Evan
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