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LX-mini Crossover Article
LX-mini Crossover Article
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Old 7th October 2018, 05:18 PM   #171
Nelson Pass is offline Nelson Pass  United States
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LX-mini Crossover Article
Quote:
Originally Posted by nzlowie View Post
Does this have a hi pass on the low frequency section? My plan was to replace the passive xover that's on my mid/hf horn's, I use a DSP bass amp for the bass section. So I have DSP and amp for bass then another amp and passive xover for the mid/hf section.
Was looking to keep the DSP bass amp and use this active xover for the horns but then realised it probably doesn't have a hi pass at its lower end, is this correct?
It does have a high pass on the bottom end. It is adjusted for high Q
to provide a 5 dB bump up at 50 Hz, but it's a simple 2 pole topology
and you can stuff it as you like.
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Old 7th October 2018, 05:22 PM   #172
Nelson Pass is offline Nelson Pass  United States
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LX-mini Crossover Article
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Originally Posted by Manolo47 View Post
Reading the article Nelson mentions that FL considered or used as parameter in this design -correct me if I’erong in this - that the minimum power rating for the amplifiers to be used in conjunction with this xover were 80 and 100. Is this really so? Us owners of FW Amos would then be disqualified...

And the volume controls. Why are there 4 controls? And if one uses, let’s say Alps attenuators in the faceplate, how would these be implemented. I would only use one for the low pass section... would it be just one? Thanks.
Siegfried and I sat down one day with LX minis. a digital scope and a
copy of Telarc's 1812 overture with the cannon shots. We played it at
what SL determined to be an adequately loud level and measured the
peak wattage from each amp, top and bottom.

The result was performance where a 75+ watt amp would do it on
the bottom and a 25 watt amp on the top.
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Old 7th October 2018, 05:23 PM   #173
Stanney2017 is offline Stanney2017  United Kingdom
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Thank you!
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Old 8th October 2018, 10:59 AM   #174
Manolo47 is offline Manolo47  Puerto Rico
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Thanks! And, what about the 5db hump at 50 hz, can that be moved to a lower frequency,, like 20 Hz?
I would be using this as a HP filter for my Spatial M4's , set at either 80 or 120 Hz and a corresponding LP filter to my "Ripole" subwoofers, would it work well for this?
I presently us a minidsp 4hd -which really is pretty good though one can instantly experiment will all kind of parameters to see which work, and sounds pretty good also.
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Old 8th October 2018, 04:51 PM   #175
Nelson Pass is offline Nelson Pass  United States
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LX-mini Crossover Article
It's a filter. You set the values and there it is. You can put the hump
where you want it by scaling the resistor/cap values, and you can adjust
the amplitude of the peak also.

Whether it works well for you depends mostly on R/C value choices you
make...
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Old 10th October 2018, 10:53 AM   #176
Manolo47 is offline Manolo47  Puerto Rico
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Default User's manual?

So, would a user's manual be offered with information as to how implement the different filter options, etc.? And would the kit have various resistors and or cap values so one can experiment with let's say, 80 hz vs. 120 hz. Xover frequencies or I would need to buy these? Thanks!
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Old 10th October 2018, 11:42 AM   #177
Dennis Hui is offline Dennis Hui  Canada
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LX-mini Crossover Article
Default pot adjustment

I have a dumb question about setting up the volume/pots of the
crossover. Assuming one amp has higher gain than the other,
the pot for the lower gain amp should be set wide open.
For the other amp, can we simply set the corresponding pot so
that both amps give the same voltage output with an input at
approx 580Hz? (I'm going by the crossover response
graph on p13 of

http://www.firstwatt.com/pdf/art_lxmini%20crossover.pdf

where the red and blue lines intersect.)

Thanks,
Dennis
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Old 10th October 2018, 03:26 PM   #178
Davey is offline Davey  United States
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Dennis,

You could do it that way. But I think the easiest/best way would be to just the appropriate potentiometer downwards until it sounds best to you.

Dave.
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Old 10th October 2018, 05:26 PM   #179
Nelson Pass is offline Nelson Pass  United States
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LX-mini Crossover Article
Quote:
Originally Posted by Manolo47 View Post
So, would a user's manual be offered with information as to how implement the different filter options, etc.? And would the kit have various resistors and or cap values so one can experiment with let's say, 80 hz vs. 120 hz. Xover frequencies or I would need to buy these? Thanks!
My intent was to put up a simulation template in MicroCap so that people
could play with values and see the results.
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Old 12th October 2018, 01:15 PM   #180
escucalin is online now escucalin
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Hello,

How are the jfets involved matched? I have experience measuring the drain source current when Vgs=0 or the gate connected to source; is it the case? Or it needs the gate resistor added for a more precise Ids?

I am investigating a way to use a stock of old jfets (i accumulated over the time) from the audio era; and use them in this superb active crossover.
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