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LX-mini Crossover Article
LX-mini Crossover Article
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Old 10th February 2019, 06:42 PM   #441
Nelson Pass is offline Nelson Pass  United States
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LX-mini Crossover Article
Quote:
Originally Posted by Jeffreyjuice View Post
I'm glad to see the three/four way pcbs are finally coming out!! Will there be unbalanced versions available for those of us who don't require balanced outs?
There is a single-ended 3-way on my to-do list which is hard-wired for the
3 different versions.
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Old 11th February 2019, 06:23 AM   #442
magicLX521 is offline magicLX521  Germany
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These plugs fit into the case cutouts

unbalanced
http://www.neutrik.de/de-de/cinch/cinch-einbaubuchsen/

or balanced
NC3FD-V | Neutrik
NC3MD-H | Neutrik

Nelsons existing board has dedicated connections for either type
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Old 15th February 2019, 08:15 PM   #443
yoshisoakland is offline yoshisoakland
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I have questions regarding a volume control in front of my lxmini crossover:

- In a first trial 10k potentiometer in front of the circuit works, but with a nominall 10k input impedance it is not ideal because the current gets shared between crossover and potentiometer. Should one use a buffer in front of the crossover, or are there other options?
- There used to be a buffer in front of the crossover (see Linkwitz lab site and other thread on diyaudio). Why was it omitted in the final version? Is there a chance to buy the matched transistors and resistors tuned to the sweet spot separately somewhere to build one more buffer? Putting a B1 buffer in fron seems a bit overkill, and using the same buffers as in the crossover seems reasonable to me.
- Is there any chance one can do this without a distortion analyser? There a cheap transishor testers around wich can match the devices, but could they be used to find the resistors for load line cancellation?
- what resistance values should a potentiometer (or one of the cheap stepped attenuators) in frong lf a buffer have? What value should a passive volume control potentiometer without buffer have?

Thanks

Last edited by yoshisoakland; 15th February 2019 at 08:18 PM.
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Old 15th February 2019, 09:44 PM   #444
Nelson Pass is offline Nelson Pass  United States
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LX-mini Crossover Article
A buffer is ideal, but if you use the potentiometers as shown, you will find that
the differences are slight. The design is set so that if you have amps
with equal gain, you can turn both pots up so that the filters see the
impedance of the source. Testing the influence of the pots at worst case
settings, we still get good results.

All of this assumes that your source can drive 10 Kohm. If not, then
a buffer would be a good idea, but you should try it without first.

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Old Yesterday, 11:54 AM   #445
Rewind is offline Rewind  Sweden
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LX-mini Crossover Article
Can it be designed to be 4-way or even 5-way instead of just 2-way? What would be the easiest way? Just buy several boards?
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Old Yesterday, 05:35 PM   #446
Nelson Pass is offline Nelson Pass  United States
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LX-mini Crossover Article
I don't see why not. Perhaps for that many channels you would just want
the crossover filters without the EQ circuits.
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Old Yesterday, 11:37 PM   #447
Rewind is offline Rewind  Sweden
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LX-mini Crossover Article
After reading the article and the thread, and briefly tried the simulation, I can allow myself three silly questions.
1. How do you remove the EQ part? I have a Minidsp 10x4Hd and never used the EQ anyway.
2. Can I just add a second PCB board and split the left and right input to get a 4-way crossover? Wouldn't that remove a lot of the signal strength?
Signal strength is why I dislike Minidsp, because it removes so much of it. If I then add another DSP like Dirac room correction the music is too anemic.
3. What happens with polarity with four stereo channels with 12dB/octave? Which speaker channel need inverted polarity?
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