Lx-mini Analog Crossover

LXmini // LXmini+2 // LXstudio ASP by Nelson Pass

As you might have heard/seen at Burning Amp 2018,
Nelson Pass did a LXmini / LXmini+2 / LXstudio ASP.
This one is fully balanced.

Together with the added woofer stage,
pcb area and parts count increase substantially (e.g. 100 JFETs) compared to the the unbalanced LXmini ASP.

Powered by +/-15V rails .
The ASP comes with a 3mm massive aluminum case, that may be fitted with Neutrik RCA or XLR plugs.

Pre-ordering possible as either
pcb with 100 matched JFETs and case or
the fully assembled ASP with case .
Delivery planned for Nov 2018.


You find a limited number of these ASPs in the webshop.
 

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Help with XL-mini Crossover kit

A friend bought this kit recently and asked me to assemble it for him. He’s into wood working and has done me lots of favors.

I assembled the kit today and all went well, except for R17-R20. The BOM calls for 4K resistors but none were provided. The label on the pcb envelope says “DIYK-XOESS-S10, kit Crossover Essentials V1.0.” I have several 10k and 100r resistors left over and some Chinese 3.9k and 4.3k on hand. Seeking advice. Thanks.
 

PRR

Member
Joined 2003
Paid Member
"R17 - R20 * supplied with Jfets – typical value ~ 4 Kohms"

You did not get resistors in the JFET bag?

They must be figured for the specific JFETs you got. They should be packed together.

If not: these give a modest reduction in THD and are a Pass "magic". However the THD won't suck even with 1Meg here. I don't know why you would have "several 10k and 100r resistors left over" (sure you didn't put the magic JFET resistors in the wrong holes?) but I'd just pop 10k or 4.3k in there and be happy.
 
Thanks for the thoughts. There were notes included that explained to expect some extra parts since it was easier to include them than to repack the kit. (Hmmm) There was an envelope with a couple of substitutes relating to the specific fets, which were installed.

Think easiest thing to do is here is to accept that 4K is correct hdetermine if my cheap Chinese 3.9Ks are adequate.
 
So I'm thinking of building a pair of LX minis, but I'm afraid I'll blow budget because there are too many items which you need which everyone assumes you already know about, so they are not mentioned.

For example, let's say I buy an Aleph-J kit from DIY audio so I have an amp. (I've already built the Amp Camp Amp, don't know if it has enough power for the LX Minis)

Can I hook the amp directly to the speakers? Or do I need to also buy/build the crossover network? Which looks like $3-400 more and another month or so of calendar time (I don't have as much free time as I'd like). Which I can do, but I don't want to find out "by surprise".

I'm already sorting through my Wayne's Linestage, which I thought would be a fun weekend project when I ordered the kit, until I learned that I also need to build a power supply and a control unit for it, and design the cutouts in the chassis to match the power ins and controls (volume, balance, input select)...

I'm not complaining, DIY is for learning and the linestage has greatly increased how much I've learned, only trying to get a better estimate of what I am really getting into. Is this a weekend project or a 6 month project?
 
The one and only
Joined 2001
Paid Member
I believe you are talking about the resistors to ground after the buffers. Not being the supplier I can't speak to the specifics, but they are used to tweak the distortion numbers of the buffers by loading them. The circuits will run fine without them and the precision of the values is not important.
 
Ideally it would be nice to drive the LX-Mini Analog Crossover directly from a DAC output, and drive the power amplifiers directly from the crossover outputs. However, it appears that the LX-Mini Analog Crossover attenuates the input signal by about 4:1 at the crossover frequency. That suggests additional voltage gain is required either before or after the crossover in order to drive the power amplifier to anywhere near maximum output. Is this correct?
 
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