Lx-mini Analog Crossover

Also, Mr. Pass could you comment on you experiences with the LX Mini both with and without the subwoofers? Sounds like you’ve spent quite a bit of time with them.

(Of course, anyone else who has experience please feel free to chime in)

I adore and almost exclusively use the old JBL monitors, along the L300 which I believe you have.

I’m wondering if I should take the plunge with the subwoofers right out of the gate, or I will miss the lower frequencies that the JBLs deliver.

I haven’t heard the LXMinis in any configuration, however their reputation has put them at the top of my list for a new speaker build and my first that’s not a simple sealed box affair.

I think the woofers would close to double the cost of the kit from Madisound.

While the Orion speakers are said to be a step up on the LXminis I just can’t justify the aesthetic compromise. Others may feel the total opposite, or not get it... but that’s just my take.
 
The one and only
Joined 2001
Paid Member
I’m wondering if I should take the plunge with the subwoofers right out of the gate, or I will miss the lower frequencies that the JBLs deliver.

For those interested in the future upgrade to the LX-mini with subs,
this crossover can be adapted to that by changing a capacitor the EQ
of the bass/mid filter capacitors. Then you apply a low pass filter to the
subs. It would be practical to consider this as an add-on, but there will
also eventually be a stand alone 3 way crossover.
 
Founder of XSA-Labs
Joined 2012
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Yes, thank you for the nice article Mr Pass. Great to see that a simple buffer using dual JFET (J113) in SE Class A can be used instead of opamps for a buffer in between the filter blocks rather than opamps.
 

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For those interested in the future upgrade to the LX-mini with subs,
this crossover can be adapted to that by changing a capacitor the EQ
of the bass/mid filter capacitors. Then you apply a low pass filter to the
subs. It would be practical to consider this as an add-on, but there will
also eventually be a stand alone 3 way crossover.
Hello Mr Pass
I would like to build the LXMini+ with your LXMini 2 way Analog Crossover.
My questions are:
1) What changes are required for the Capacitor on your 2 way Crossover. (Specs of Capacitor)
2) I will be using a MiniDsp for the configuration of the Subwoofers, I have asked Dave to provide me with the MiniDSP Configuration File for the Subwoofers
3) I am assuming that for this configuration, nothing will be changed for your LXMini ASP 2 Way Crossover except for the High Pass filter (@ low end frequency of when the sub is intergrated) to the 2 Way ASP XO and a low pass filter to the sub. The EQ of the Sub will be handled by the MiniDSP based on the configuration files by Dave for his "Davey's Sub" implementation of the LXMini+.

Hope my question makes sense and thank you for the work you have put in for the LXMini ASP.

Many thanks also to Dave for his hardwork for providing the option of LXMini+. (Addition of Peerless subs to the LXMini)
 
The one and only
Joined 2001
Paid Member
Referring to the crossover schematic in the LXmini crossover manual,
the LXmini bass circuit high pass filter is C5, C6, R7 and R8. Here are
the original values, and the provisional new values ones for the
woofer/mid used with the sub.

C5 = 100 NF ----> 47 NF

C6 = 150 NF ----> 47 NF

R7 = 8.2 K ----> 270 K

R8 = 100 L ---> 180 K
 
I respectfully request a link to the analog xo. I looked for a long time. The page for Mr. Pass's first link appears to lack text "LX mini" and "analog crossover."

Can I build the LX Mini xo as stereo analog HP filter, 4th order, high pass only function? I have no need nor desire for any other function. Maximum resolution and transparency is prime priority.

1st choice: multiple (6 to 8) pole frequencies evenly spread from approximately 60 to 150 Hz. 2nd choice: Fixed 70 Hz pole.

Change pole frequency, if such option is possible: 1st choice, front panel switch...2nd choice, swap internal parts.

Sincere thanks for Mr. Pass's valued time and expertise.

If not Mr. Pass's xo, I respectfully request suggestions for the stated application.
 
Account Closed
Joined 2001
My apology Mr. Pass, for mis-typing. I meant stereo (2-ch), 4th order, unbalanced OK.

I prefer ability to select one of multiple frequencies between about 60 -150 Hz, but 70 Hz fixed is Okay.

Nelson linked to his paper showing the schematic. What you're asking for is quite a bit different than the toplology implemented.
To get 4th-order you'd have to feed one of the outputs back to the input of the other side, and then replace resistors with capacitors and capacitors with resistors on one side.....among other issues.

You are aware of this, yes???

Dave.
 
Hi Nelson,

There was a thread a while ago about a "B1 active crossover" where some of us discussed using BF862. (I never had the time to build one.) Would BF862 work well in place of J113 here? They're very low-noise... I presume the biasing resistors would need to be adjusted, although I don't know how. Since the whole circuit is very low-power you could presumably use little adaptor boards like juma used in a thread ages ago and not have trouble with heat.

Alternatively, maybe a little DIP-8 adaptor board could include both jfets and little surface-mount resistors, so the buffers would have the same footprint as an op-amp. (Although this wouldn't fit the PCBs of course...)

Thanks for the fascinating article!