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Juma's LSK Preamp - through hole version

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prasimix

prasimix

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Joined 2009
#1
This thread is for anyone interesting in building Juma's JFET preamplifier presented here.

I prepared two versions of PCB: with power supply for two or one channel. We should decide which PCB to use or we can go with two GB if price is acceptable. Both version can host 2SK24/2SJ103 or 2SK170V/2SJ74V (check in BOM).

Please find in attachment the latest schematic, PCB layout and BOM for both version.

EDIT: Please note that both layout is now obsolete. Improved version can be found in most recent posts. Group buy list with prices are available here.

EDIT2: PCB can be also used for Phase splitter menitoned here.

EDIT3: Preparation for the second GB is under way. New layout for single channel PCB is presented in post #241. Dual channel version will include small correction in Power supply section as shown in post #217.
 

Attachments

  • Juma preamp rev.2.1 dual schematic.png
    Juma preamp rev.2.1 dual schematic.png
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  • Juma preamp rev.2.1 dual.png
    Juma preamp rev.2.1 dual.png
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  • Juma preamp rev.2.1 dual BOM.pdf
    Juma preamp rev.2.1 dual BOM.pdf
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  • Juma preamp rev.2.2 single schematic.png
    Juma preamp rev.2.2 single schematic.png
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  • Juma preamp rev.2.2 single.png
    Juma preamp rev.2.2 single.png
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  • Juma preamp rev.2.2 single BOM.pdf
    Juma preamp rev.2.2 single BOM.pdf
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#5
BigE said:
I'd be interested in the LSK circuit board *only* with no power supply section.
Click to expand...

Hm, that complicate a whole thing. I tried to make another layout where you can simply cut PS section if you do not require it. For DC power you can use J4 connector. Unfortunatelly this introduce 3 additional position for resistors (R10A, R13A and R23A) and one jumper just below C7.

I will go with this solution if other members which is already shown interest for solution with PS do not have a problem with such approach.
 

Attachments

  • Juma preamp rev.2.3a single.png
    Juma preamp rev.2.3a single.png
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#10
tinitus said:
could it be made 'break-off' at the shown dotted line ?
and with solder pads for connect jumpers, if used without breaking
Click to expand...

I don't like to introduce jumpers if they are not really necessary. Here I can add perforation to make cutting job even more straightforward. Learned from some other project such perforation will not jeopardize mechanical strength of the board.
 

Attachments

  • Juma preamp rev.2.3b single.png
    Juma preamp rev.2.3b single.png
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#14
Here is the price for qty of 20 (dual) or 40 (single):

1. Dual channel (PCB 120x143mm, 1.6mm, FR4, 70um, 1-layer, red or blue, HASL) ... 14 EUR
2. Single channel (PCB 70x212mm, 1.6mm, FR4, 70um, 1-layer, red or blue, HASL) ... 20 EUR/pair (10 EUR/each)

I'll check for P&P but it should be 5-6 EUR for Europe, and maybe around 10 EUR for other destinations.

Please let me know if that is acceptable. We can expect even better price for larger quantity.
 
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#16
prasimix & Co.:

I'd be interested in trying this preamp out, but like tinitus would rather have separate preamp and power supply boards; I like my power supplies as far from the audio lines as reasonably possible. Would this be possible, and is there enough interest to support this design change?

Regards,
Scott
 
#19
SRMcGee said:
... but like tinitus would rather have separate preamp and power supply boards
Click to expand...

don't know, but maybe I would

but I know the members 😉

and I also know that putting it all into a box often reveals unforseen difficulties
seperate boards might be more 'flexible'

and if you only have space for one power supply, it could still power two channels
and you have a very nice spare power supply for another project

board prices looks good
and I'm in on whatever it will be
 
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