LX-mini Crossover Article

Jump to Latest
#41
:cheers:
 

Attachments

  • lxmini kit.jpg
    lxmini kit.jpg
    39.9 KB · Views: 2,529
#48
Free giveaway for LXmini builders

Hi,

we have parts from our LXmini-kit production as a free giveaway:

  • Round LXmini baseplates, HDF precision mitered, dark anthracite with lower-side cable canals and 5 predrilled mounting holes for rubber feet
  • 4" end caps for the lower tubes
One set per builder, only, as long as stock lasts.
LXmini construction plans (outside EU 19% VAT is deducted after registering).

Shipping is free within Germany,
20€ for EU , 40€ outside EU

Contact info@magicLX521.com with your shipping address.

Best
Frank
 
#49
Good news and thank you papa for another great work.

I am considering building +2 or studio, should I wait for the next release or I can build these boards and just add on the subwoofer channel like an "expansion" board?

Example in balance mood, 2 of these PCB + 1 or 2 future PCB for the sub?
 
#50
I am subscribed to this thread, so it isn't that much trouble to wait, but is there a timeline for putting the kits on the storefront? Just want to order the day it comes out 🙂

It will keep me from checking a non-updated store front 2x daily.

Thanks,
 
Last edited:
#52
Nelson,

I hope you don't mind a few questions / remarks.

I find it a pity that you spend much of your article on the NJFET follower, and little or nothing on the Sallen Keys.
Undoubtedly using a pair of J113 to get such low distortion is very clever.
But it is perhaps worth mentioning that in doing so, the DC across input and output of the follower is not zero.
It is only made possible by using single rail and decoupling caps.
So split rail and DC couple would not work, if I am not wrong.

In any case I find that this is still a compromise.
What made you choose J113 when you can choose 2SK209GR instead, which is equally low cost and available ?
And IMHO better than J113 in many respect.

You also use a somewhat heavy gate stopper for the signal carrying FETs, but nothing for the CCS's.
Is that a random choice, or did you experience oscillations ?
1k is not a small value when some of the resistors are even below 10k in the Sallen Keys.

Perhaps you would also kindly tell us how you chose the parameters for the Sallen Keys (e.g. what Q value).
And whehter you decided to swap the first and second stages from your original schematics (P.2) to the final (?) one in P.7 for specific reasons.


Thanks in advance,
Patrick
 
#54
Yes, using a very high Idss and then include a large source resistor will make things look much better.
I never need to tweak Toshiba's.
And then we can also start to compare Zout, noise, max. voltage, ..., etc.

But we are both happy with what we use, so everyone is happy. 😉


Cheers,
Patrick
 
#55
EUVL said:
I find it a pity that you spend much of your article on the NJFET follower, and little or nothing on the Sallen Keys.

It is only made possible by using single rail and decoupling caps.
So split rail and DC couple would not work, if I am not wrong.

What made you choose J113 when you can choose 2SK209GR instead, which is equally low cost and available ?
And IMHO better than J113 in many respect.

You also use a somewhat heavy gate stopper for the signal carrying FETs, but nothing for the CCS's.

Is that a random choice, or did you experience oscillations ?
1k is not a small value when some of the resistors are even below 10k in the Sallen Keys.

Perhaps you would also kindly tell us how you chose the parameters for the Sallen Keys (e.g. what Q value).
And whehter you decided to swap the first and second stages from your original schematics (P.2) to the final (?)
one in P.7 for specific reasons.
Click to expand...

In order of asking,

The filter parameters were the ones approved by SL after listening
tests. Sallen Key design is old hat - much more interested in fiddling
way to use cheap/available fets.

The project is intended for cheap single supply wall-wart switcher. Split
supplies are another category of cost and availability. DC coupled version
is a whole other category of DIY complexity and cost.

I have nice artwork for the same using the 2SK170/2SJ74 if people
want to pay for it...

2SK209? I go to Digikey and see discontinued which tells me not
to bother specifying in future projects. Also it's surface mount, a real
treat for me and most DIYers.

1K is a heavy gate stopper on the Jfet? It's been my default for years,
even on the Beast with 1,000 Jfets.

The CCS doesn't seem to need it, so I left it off, and that has also worked
for years without problems.

:geezer:
 
#58
Only a meager selection of Sanyo/On Semi low noise n channel left but they are all 15V Vdsx parts.
The 2SK3666 may be a bit more useful at 30V Vdsx and Yfs 6.5 mS, but has 2x noise which may still be passable for line level duty.
 
You must log in or register to reply here.
Top Bottom