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Old 21st November 2012, 01:00 AM   #11
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re:'stay well away from x/o calculators" - I have to disagree with this, with the caveat that though they are temptingly easy for beginners, the level of knowledege you need to use them well is quite high... (& assuming you find an accurate one)
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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 21st November 2012, 02:48 AM   #12
Dissi is offline Dissi  Switzerland
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Hi,

I have a concrete proposal for your crossover problem:

SimulationElves1111.jpg

CrossoverElves1111.jpg

I made the simulation using the 4 ohm version of the woofer. I hope that's the one you have. Note that the driver is not really suited for a vented box. Therefore I highly recommend to seal the vents, you will get a much better bass! The simulation assumes a closed box and a microphone distance of 2 meters.
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Old 21st November 2012, 05:40 AM   #13
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Hi, There is something wrong in this sim, I use actual measurements to sim your proposal, I have a low z nearly 2ohms at 100Hz ! the problem is the 150uF
The sensitivity 84dB is too low, Keep it at least at 87dB. This speaker will be near a wall. The bass step with this drivers is less than 6dB, ~3dB
The phase tracking is bad ..

Can you redesign it ?

Quote:
Originally Posted by Dissi View Post
Hi,

I have a concrete proposal for your crossover problem:

Attachment 313075

Attachment 313076

I made the simulation using the 4 ohm version of the woofer. I hope that's the one you have. Note that the driver is not really suited for a vented box. Therefore I highly recommend to seal the vents, you will get a much better bass! The simulation assumes a closed box and a microphone distance of 2 meters.
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Old 21st November 2012, 05:56 AM   #14
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Quote:
Originally Posted by jerome69 View Post
Hello,
Click the image to open in full size.
The topology of this schematics is good but i see some improvements
1. Reverse the polarity of the tweeter
2. On the mid increase L2 to 1mH and add 10 ohms in series with C2

Have fun.
Oups, only the polarity of the midrange 4V813 needs to be reversed Keep the woofer and tweeter with the same polarity.
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Old 21st November 2012, 06:44 AM   #15
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right on! thanks for all the responses! so if the nominal impedance isn't what is used to pick the crossover point, how is it decided? i'd much rather base it around 8ohms if can. also, can't find specs for focal 8v413, even contacted focal, and they don't have them anymore! they said its the same as 8v412 model, but can't find spec sheet with any charts or graphed response. i've compiled the three specs into one wordpad page for easier reference.
basically, i'm not to picky, i'm mainly wanting good slightly forward midbass that aren't recessed or muddy and pronounced low bass response that has a tighter attack/decay without bloated sustain/release (not sure if terminology is correct,just trying for an example). i think that a closed box would achieve this better, but am trying to avoid building new boxes.
i play experimental acid jazz/IDM/drum n bass/ambient/abstract/electronic dance music using mostly analog synths/sequencers/drum machine with some acoustic percussion thrown in sometimes. so my main focus is to play my music thru them so using for home theater isn't my objective.
can i use a Moog Voyager to test the specs for the speakers? it has a variable 1-4 pole 24/dB lowpass/bandpass filter that spans 20Hz-12kHz, plus 3 oscillators that span 8 1/2 octaves with tunable frequency control that dips below 20Hz -. it has a noise generator but its hybrid pink/white noise. i also have a separate resonant bandpass filter that is tunable from 110Hz - 1.8kHz.
have looked into using Speakerworkshop to test the speakers, but not wanting to do more work than have to in order to get good sound out of these.
i didn't mention that there is a crossover he designed already hooked up to them, but i don't trust it enough to continue using it even if i'm barely sending any power into them. i've looked at every x-over design i can find, and there is nothing even remotely similar, other than i think he's got somekind of zobel circuit in it. but it doesn't have any capacitors! its composed of

1 Steel Laminate 5.5 mH 15 AWG Inductor rated at .257 DCR ohms

1 Madisound 0.15 mH 19 AWG Air Core Inductor .10 DCR ohms 100 watts

2 15 ohm, 25 watt, Cement Type Wirewound Resistor, 5mm Ceramic Core, Perfect Winding, Solder plated copper leads,
1 thats 10% Tolerance
1 thats 5% Tolerance

I labeled which wires he has going to which drivers using red white and blue

red:tweeters
white:mids
blue:woofer
i then have the output polarity phases as:
redositive
white:negative

not sure if this is standard but matched according to the crossover wires blue/black positive/negative

My friend that designed these speakers and x-overs works for a renowned speaker wire company called Kimber-Kable, but these were his first speakers, which he made back in '98.unfortunately i've not been able to find him in years. otherwise, i would be asking for his help instead.

one more thing, if i was to go the active x-over route, would a 2 channel amp (crown ce2000) suffice, or would i need a separate amp per driver?

thanks and thanks again, i'm very grateful for this forum! keep it real....
Attached Images
File Type: jpg DSCN2137.jpg (512.0 KB, 103 views)
File Type: jpg DSCN2146.jpg (515.3 KB, 94 views)
File Type: jpg DSCN2131.jpg (767.2 KB, 88 views)
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Old 21st November 2012, 06:49 AM   #16
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oops! had to change manufacture specs attachment to an allowed document format.
Attached Files
File Type: txt focal Xover specs2.txt (3.1 KB, 12 views)
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Old 21st November 2012, 09:43 AM   #17
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8V412 : http://lephenixnoir.net/images/pdfs/8v412.pdf
TC120TD : http://www.diyparadiso.com/datasheet...l/TC120TD5.pdf

Let us know how things go.

Last edited by jerome69; 21st November 2012 at 09:56 AM.
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Old 21st November 2012, 10:24 AM   #18
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404 on the top link jerome
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Old 21st November 2012, 10:37 AM   #19
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Query? have you listened to them using the cross-over "As-Is"?

from a look at the wiring the woofer runs open and the others are used with a 1st order series XO, some-one took a lot of time to braid those wires together.
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Old 21st November 2012, 11:26 AM   #20
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I just googled the NHT and looked at the original XO for the woofer, crossed using an iron core 12mH inductor and 200uF in parallel. I wouldn't change that in designing a new speaker.
Shame they are not still available too
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