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AKSA's Lender Preamp with 40Vpp Ouput GB

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P

pcgab

Member
Joined 2014
xrk971 said:
I am having a hard time sourcing the little cylindrical 0204 MELF SMT resistors from Mouser or Digikey in the USA. Does anyone have a vendor that has these in stock? I may have to improvise with 0805 chip resistors.
Click to expand...

I tried Farnell, and they wanted way too much for shipping. Mouser and Digikey didn't carry more than a few values of the needed resistors.

I've not found a source yet.
 
xrk971

xrk971

Founder of XSA-Labs
Joined 2012
etsy.com/shop/XRKAudio
Paid Member
GB Status Update

PS64 - 1 set SMT, Paid
Redarc12 - 1 set, TH, Paid
CFT - 1 set, TH, Paid
Jacques Antoine - 1 set TH, Paid
Silasmellor - 1 set THT, Paid
Bvtrinh- 1 set TH, Paid
bvtrinh - 1 set TH (second set), Paid
ggetzoff - 1 set TH, Paid
tubesguy - 1 set TH, Paid
Aatto - 1 set SMT, Paid
Mordikai - 1 set TH, Paid
Johnny2Bad 2 sets total 1 TH & 1 SMT, Paid
vvs07 - 2 sets TH, Paid
PCGAB - 1 Set SMT, Paid
Harry3 - 1 set MB plus TH, Paid
Wayne1 - 1 set TH, Paid
obh - 1 Set TH, Paid
PJN - 1 set TH, Paid
Zman01 - 1 set SMT, Paid
AKSA - 1 set SMT, Paid
xrk971 - 1 set SMT, Paid
spind - 1 set TH, Paid
schlomoff- 1 set TH, Paid
Prasi - 1 set TH, Paid
muthumuthiah - 1 set TH, Paid
Algar Emi - 1 set, TH, Paid
Kokanee - 2 sets, 1 TH and 1 SMT, Paid (moved up from FB2)

—— List for GB #2 - please add name below ——

*Thimios - 1 set SMT, Need PayPal address
*Fabian85 - 1 set SMT - need PayPal address
Pinnocchio - 1 set SMT, Paid
Mituisho - 1 set SMT, Paid
Alurudin - 1 set TH, Paid
muthumuthiah - 3 sets all TH, ship all with order from GB #1, Paid
jwjarch - 1 set TH, Paid
briansz - 1 set TH, Paid
steefdebruijn - 2 sets TH + spare set SMT daughterboards, Paid
jmc207 - 2 sets: 1 TH and 1 SMT; +1 spare set TH daughterboards, Paid
*marcus22ch - 2 sets SMT, Invoice sent
*vanofmonks - 1 set TH, Please send PayPal address
*pfisl - 1 set TH, please send PayPal address
Click to expand...

GB#2 at 18 sets so far
 
Last edited:
P

pcgab

Member
Joined 2014
xrk971 said:
Pcgab,
Let us know how that goes. For the purposes of verifying the PCB I will have to improvise with 0805’s chip resistorsfor for now.

Btw, I think a standard (smaller type) 1/4w or 1/8w carbon film or metal film axial can have leads bent to fit an SMT MELF package?
Click to expand...

Distrelec didn't have them afterall.

I was planning on trying to fit some 1/4w metal film axial's once the boards arrive.
 
xrk971

xrk971

Founder of XSA-Labs
Joined 2012
etsy.com/shop/XRKAudio
Paid Member
GB #1 PCB's Arrived!

The boards arrived and they look great. I have never had such a big heavy shipment before - amazing how much FRP, copper, and lead weighs.

Again, thank you to Aksa for the design and JPS64 for the layout! This is truly a superb "professional" layout - very similar to what you would see in a final end-product. You will notice extensive use of copper pours/ground planes, separation of signal and power ground planes, nice connectors to allow the boards to be placed in the users' case with the most flexibility as to where input/output jacks go, etc.

I think I will have to separate the mother and smaller break-way sub-boards in order for it to fit in a reasonable size package for shipment. As is, the MB is a little over 6.2in x 6.2in square shape which is an odd size to fit in a standard padded envelope.

Here are some photos...

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For the purposes of testing out the boards, I will install the essential parts and leave off the connectors etc as I don't have them yet. But I should be able to verify that the preamp circuitry, cap Mx, etc all works. I am waiting for my order of the essential parts like DN2540, BSP129, electrolytic caps to arrive.
 

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Last edited:
xrk971

xrk971

Founder of XSA-Labs
Joined 2012
etsy.com/shop/XRKAudio
Paid Member
For those of you having a hard time sourcing the MELF resistors, JPS64 said that he will provide a set to make two SMT daughterboards for 3 Euro. He did check with Mouser (USA) to verify that they were in stock before he finalized the layout. There must have been a big project somewhere in the US that wiped out all the stock. Send JPS64 a PM if you would like a set. Or perhaps we can start a MELF resistor GB list here even.
 
xrk971

xrk971

Founder of XSA-Labs
Joined 2012
etsy.com/shop/XRKAudio
Paid Member
Metal Electrode Leadless Face (MELF) resistors, because they are round and can roll or eject off the end of a tweezer, they are also known as Most End up Lying on the Floor...

KOA SPEER makes them too. I suppose in the future 0805 pads would be useful as it allows either low cost easy to find chip or MMU (0102) MELF to be used.

RN41, RM41 | KOA Speer Electronics

From Wikipedia, advantages of MELF:

Despite their handling difficulties, and in the particular case of MELF resistors, they are still widely used in high-reliability and precision applications where their predictable characteristics (e.g., low failure rate with well-defined failure modes) as well as their higher performance in terms of accuracy, long-term stability, moisture resistance, high-temperature operation far outweigh their disadvantages.
Click to expand...
 
Last edited:
xrk971

xrk971

Founder of XSA-Labs
Joined 2012
etsy.com/shop/XRKAudio
Paid Member
GB Status Update:

JPS64 - 1 set SMT, Paid
Redarc12 - 1 set, TH, Paid
CFT - 1 set, TH, Paid
Jacques Antoine - 1 set TH, Paid
Silasmellor - 1 set THT, Paid
Bvtrinh- 1 set TH, Paid
bvtrinh - 1 set TH (second set), Paid
ggetzoff - 1 set TH, Paid
tubesguy - 1 set TH, Paid
Aatto - 1 set SMT, Paid
Mordikai - 1 set TH, Paid
Johnny2Bad 2 sets total 1 TH & 1 SMT, Paid
vvs07 - 2 sets TH, Paid
PCGAB - 1 Set SMT, Paid
Harry3 - 1 set MB plus TH, Paid
Wayne1 - 1 set TH, Paid
obh - 1 Set TH, Paid
PJN - 1 set TH, Paid
Zman01 - 1 set SMT, Paid
AKSA - 1 set SMT, Paid
xrk971 - 1 set SMT, Paid
spind - 1 set TH, Paid
schlomoff- 1 set TH, Paid
Prasi - 1 set TH, Paid
muthumuthiah - 1 set TH, Paid
Algar Emi - 1 set, TH, Paid
Kokanee - 2 sets, 1 TH and 1 SMT, Paid (moved up from FB2)

—— List for GB #2 - please add name below ——

Thimios - 1 set SMT, Invoice sent
*Fabian85 - 1 set SMT - need PayPal address
Pinnocchio - 1 set SMT, Paid
Mituisho - 1 set SMT, Paid
Alurudin - 1 set TH, Paid
muthumuthiah - 3 sets all TH, ship all with order from GB #1, Paid
jwjarch - 1 set TH, Paid
briansz - 1 set TH, Paid
steefdebruijn - 2 sets TH + spare set SMT daughterboards, Paid
jmc207 - 2 sets: 1 TH and 1 SMT; +1 spare set TH daughterboards, Paid
*marcus22ch - 2 sets SMT, Invoice sent
vanofmonks - 1 set TH, Paid
pfisl - 1 set TH, Paid
Click to expand...

18 sets in GB #2
 
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