AKSA's Lender Preamp with 40Vpp Output

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#362
SMT board is now verified working.

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Very similar performance to TH version, a tad higher THD (+2PPM):
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Thanks for the great layout JP!
:cheers:
 
#366
I listened to this preamp for a few songs. Very very nice. Great to have a unified PSU cap Mx. I really like the swappable amp core modules. This will lead to some experimenting for sure. Headphone amp version is but a swap away (don’t forget to drop Vcc). That huge heatsink on the cap Mx is not even warm when running as a preamp. But will get warm when running as a headphone amp with more bias current. It’s well sized (probably over sized) though.

Looking forward to using this with input selector and real case. It’s a very easy amp to build if you have the right MELF parts (or wait for the 0805/1206 chip version). The TH board was a no brainer. They can be assembled in under an hour.
 
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#367
Star Ground Plane

So I was looking more carefully at the layout now that I have it in my hands and hear how good and low noise it sounds. Look carefully at the top side of the PCB and notice the well-orchestrated cuts in it that divide the various sections of the amplifier: cap Mx/CRCRC, left PSU, right PSU, left analog, right analog (down to the split at the dual-gang volume pot pins), and the branches all originate from the centrally mounted star point X121 connector. Just wanted to give my hats off to JPS64 for such an elegant and well-thought out design. I have never seen such a nice star ground plane implemented in DIY before. I asked JP how he designs the ground plane, he said "You have to think like an electron!" Indeed. 🙂

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Well, it's working out very nicely.
 
#373
If anyone can find deals on the special RCA jacks that would be appreciated. They are currently circa $9ea from mainstream dealers. Actually, I am having a hard time finding them.

Part No: 12HP059-BLACK

Part No: 12HP059-RED

Article No LCHQRCA

Priced $9.89/pair from Hificollective. Could not find on their website.

I wondering if this can work?

RCJ-022 CUI Inc. | Connectors, Interconnects | DigiKey

An externally hosted image should be here but it was not working when we last tested it.


JPS64,
Can you please share with us what the 3D render of the RCA jack looks like so we can find a cheap substitute?

Or is this closer?

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http://www.morethanall.com/upload/products_pdf/15646360353ace67def498.pdf

Here is the PCB pattern for the above jack.
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#376
Hello X,

do you´ve a price for a pair from Morethanall?

We´ve three solutions:
- GB for right RCA PCB high quality but depends on demand
- cheap RCA but will check first PCB replacement and it´s IMHO a bad choice then good preamplifier but bad connectors
- standard rear plate mounted RCA connector connected to PCB using wire

JP
 
#378
@jwjarch

It´s OK. If short distance between RCA and PCB I would go with simple wire (like Mr. Pass designs).

OK, here a solution:
- use 2p. header, the same as used for X141 to replace all RCA on PCB (2.54mm pitch)
- use assembled 2 wire socket (short length if necessary)
- twist the cable and solder directly on RCA socket (use shrinking tube for isolation and secure fixation)

Photo attached (showing technique for Pass HPA I´ve built).

JP
 

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#379
- use assembled 2 wire socket (short length if necessary)
- twist the cable and solder directly on RCA socket (use shrinking tube for isolation and secure fixation)
Click to expand...

This works well for me and lets me use the standard RCA panel jacks I have already have. So to confirm, the pitch for the pins is 2.5mm and standard 2pin JST PCB connector can be used here?

Are those Morthenal connectors the correct size? I will have to see if they are even in stock.

Edit: I don't have boards in front of me - I will look at it closely as soon as I can.
 
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