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Crossover calculators


Dave A

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I have been fiddling with making crossovers for these 904's + 510 horns I have here. So I go to places like Erse and DIY and others to look at crossovers and trying a 2nd order HF Butterworth last night was really bad. I followed the recipe and it showed the same components for the HF and LF sides and the only difference was where the capacitor was placed as in before or after the inductor. For a 659hz crossover it shows to use a 2.77mh inductor and a 21.something uf capacitor. Sounded terrible and yet this was the recommendation. The original 904 type bass bin I worked on was from a KP-450 and then a KPT-456 both of which had a 2.75mh inductor and a 50uf poly cap. Nothing at all like the crossover calculators said to use. Where is a good place to go to start learning about this? 

 

  I have analytical tools like REW and TrueRTA and the UMike here. Is the best way to start doing this might be to set it all up in the Xilica first and then take that and somehow use the settings in the Xilica to determine components for a crossover and how do you do that? I am hampered by distance from people I know who could help so trying to find a wise direction to seek here.

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1 hour ago, Dave A said:

I have analytical tools like REW and TrueRTA and the UMike here. Is the best way to start doing this might be to set it all up in the Xilica first and then take that and somehow use the settings in the Xilica to determine components for a crossover and how do you do that?

Yes. Also use DATS or REW and associated calibration resistor to measure the full range electrical impedance of the drivers/horns/bass reflex boxes. 

 

Then export the results into XSim (more on this freeware app here). Then you can do the crossover filters and see the predicted response in acoustic output amplitude, phase and impedance value and phase vs. frequency to make sure that the impedance doesn't drop too low and the impedance phase doesn't go off the chart by using a certain passive network configurations--before actually putting the L's, C's, and R's together in a network on a breadboard (i.e., simulation is much better than cut-and-try passive crossover approaches). Notch filters are needed to EQ the system flat again (a little playing around with values might be required).  There are better crossover filter packages out there (VituixCAD and LspCAD-with LspCAD being the standard which other crossover network packages are measured, and is the app that I believe Danley and Klipsch use).

 

The K-510 and K-402 horns are controlled directivity, so their output...by definition...will not have flat SPL vs. frequency.  Putting in the required notch filters to EQ within the passive crossover is required, unless you're going to EQ upstream of the loudspeaker using REW to find the required PEQs in a parametric equalizer.

 

Chris

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5 hours ago, Dave A said:

I have been fiddling with making crossovers for these 904's + 510 horns I have here. So I go to places like Erse and DIY and others to look at crossovers and trying a 2nd order HF Butterworth last night was really bad. I followed the recipe and it showed the same components for the HF and LF sides and the only difference was where the capacitor was placed as in before or after the inductor. For a 659hz crossover it shows to use a 2.77mh inductor and a 21.something uf capacitor. Sounded terrible and yet this was the recommendation. The original 904 type bass bin I worked on was from a KP-450 and then a KPT-456 both of which had a 2.75mh inductor and a 50uf poly cap. Nothing at all like the crossover calculators said to use. Where is a good place to go to start learning about this? 

 

Why not just use the actual 904 crossover design?

image.png.3b01397fcf92b9efd3c460968d31fff5.png

or if you wanted you could use the KPT942...  which replaces the 50uF with 75uF and the 4.7uF with 6uF (inductor values don't change). I don't have a pic of the schematic for the 942 but I do happen to have the physical network. The 942 was obviously intended to be used with a 402 and not a 510 but it crosses high enough (500-600Hz-ish) to potentially be used with the 510? Stock 904 crosses at 800Hz according to the spec sheet I have, always looked more like 900Hz-ish whenever I played around with it?

 

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3 hours ago, CANT said:

 

Why not just use the actual 904 crossover design?

image.png.3b01397fcf92b9efd3c460968d31fff5.png

or if you wanted you could use the KPT942...  which replaces the 50uF with 75uF and the 4.7uF with 6uF (inductor values don't change). I don't have a pic of the schematic for the 942 but I do happen to have the physical network. The 942 was obviously intended to be used with a 402 and not a 510 but it crosses high enough (500-600Hz-ish) to potentially be used with the 510? Stock 904 crosses at 800Hz according to the spec sheet I have, always looked more like 900Hz-ish whenever I played around with it?

 

 

The schematic that CANT posted is my one crossover that doesn't look like OEM because there is no PCB.  My other six have the autotransformer, polyswitch and resistor.....don't know why. One says KPT-904M-B the other six say KPT-904M.

 

Do you have an xilica or access to one?

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10 hours ago, Dave A said:

it showed the same components for the HF and LF sides and the only difference was where the capacitor was placed as in before or after the inductor.

I don't know if you are just mis stating what the schematic shows or what but Low Pass filters have inductors in series with the load and capacitors in parallel. High Pass filters just the opposite. If all you were changing was the position of a series capacitor I'll sure bet it sounded like crap.

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16 hours ago, CANT said:

 

Why not just use the actual 904 crossover design?

image.png.3b01397fcf92b9efd3c460968d31fff5.png

or if you wanted you could use the KPT942...  which replaces the 50uF with 75uF and the 4.7uF with 6uF (inductor values don't change). I don't have a pic of the schematic for the 942 but I do happen to have the physical network. The 942 was obviously intended to be used with a 402 and not a 510 but it crosses high enough (500-600Hz-ish) to potentially be used with the 510? Stock 904 crosses at 800Hz according to the spec sheet I have, always looked more like 900Hz-ish whenever I played around with it?

 

The OEM crossovers I have for this are bright and I have been told this is because they were meant to go through a movie screen and not be sitting out in the open during use. They are bright with the OEM crossovers and annoyingly so. I don't know the lower limits to the 510 horn but Klipsch says 900 hz for HF crossover. I wanted to try to get down to say 650 if possible as what I have been told is that the more you can make the horn do within it's inherent limitations the better off you are.

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12 hours ago, risingjay said:

 

The schematic that CANT posted is my one crossover that doesn't look like OEM because there is no PCB.  My other six have the autotransformer, polyswitch and resistor.....don't know why. One says KPT-904M-B the other six say KPT-904M.

 

Do you have an xilica or access to one?

I have a xilica. I have fiddled with this setup and bi-amping these but the ones I am fixing to sell I want to be run with passive crossovers. 90% of the people I sell to want plug and play only.

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4 minutes ago, glens said:

So put a resistor in line before any other elements, like in the Jube schematic: to taste.  Try the range given in that Jube schematic.  Was it something like 2 - 4 ohms?

I don't know and I will go have a look.

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2 hours ago, Deang said:

Well yeah, it would be bright, since the speaker is designed for behind the screen. 

 

Since you don't have an impedance plot, maybe an L-pad would be better. Start by knocking off 3dB. Is that a 16 ohm driver?

 

It's an 8 ohm.  Any specific L-pad you would recommend because I'm going to do this for the 3 crossovers I'm building then plug in the real resistor when it's dialed in.

 

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On 3/18/2020 at 2:53 PM, risingjay said:

 

It's an 8 ohm.  Any specific L-pad you would recommend because I'm going to do this for the 3 crossovers I'm building then plug in the real resistor when it's dialed in.

 

https://www.ebay.com/itm/L-Pad-50W-Mono-1-Shaft-8-Ohm/221540014845?epid=1501513264&hash=item3394d05afd:g:t1EAAOSwPe1UBzpA

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On 3/18/2020 at 4:05 AM, Dave A said:

The OEM crossovers I have for this are bright and I have been told this is because they were meant to go through a movie screen and not be sitting out in the open during use. They are bright with the OEM crossovers and annoyingly so. I don't know the lower limits to the 510 horn but Klipsch says 900 hz for HF crossover. I wanted to try to get down to say 650 if possible as what I have been told is that the more you can make the horn do within it's inherent limitations the better off you are.

image.png.3b01397fcf92b9efd3c460968d31fff5.jpg.44f77b63c9ff4e3ecf4d91874a32cb8a.jpg

 

No change to inductor or capacitor values so frequency response curve stays same shape, only high frequency drops 6-8 dB's, very little change to impedance, and it drops the crossover frequency a little bit. If highs are "annoyingly' high, a 3dB cut won't do it.

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Bottom line it is an art and in particular, for home settings and where you aren't selling the speakers soon.  You can play with the target impedance and other parameters to provide much better system matching (amp / speaker / room) than you can get with off the shelf crossovers and OEM build speaker systems.,   Measure along the way since you can only use calculators to start you off.  That is the technical part.  The art is the voicing.

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