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ClaveFremen 28th April 2013 07:17 PM

My_Ref Fremen Edition GB (Second run)
4 Attachment(s)
Hi all,

it seems, from the number of requests that the previous GB was missed by a lot of people so I'm organizing a second run.

The My_Ref Fremen Edition is a variation of Mauro Penasa's My_Ref with this goals:
  • a more stable and performing amp using SMD parts
  • raise LM318's PS voltage thanks to a voltage limiter
  • better PS for LM318
I've designed a brand new PCB with these features:
  • bigger caps (16mm diameter with both 7 and 5 mm pads) for C1, C2, C9
  • large use of SMD components
  • quite all small caps and some critical resistors are still through-hole
  • very small paths thanks to SMD
  • ground planes design
  • zener limiter based on schematic 5b from this link (which seems pretty similar to My_Evo one)
  • CCS shunt PS for the LM318
  • An alternate C9/R10 arrangement
  • Different grounding
  • Different compensation
  • a double diode bridge like in most gainclones
Both PCB and schematic have been tested organizing beta and release candidate mini group buys

I've been authorized by Mauro Penasa to proceed with this My_Ref derivate amp.

You can find references on development, beta and release candidate here:

My_Ref Fremen Edition - need help on PCB evaluation - diyAudio
My_Ref Fremen Edition - Beta build/Fine tuning - diyAudio
My_Ref Fremen Edition RC - Build thread - diyAudio
My_Ref Fremen Edition - Build Thread

On my Google Drive you'll find:

Build Tutorial

There's also a shared Mouser BOM to order parts.

And a YouTube video on SMD soldering of FE modules.

Actual price will depend on number of partecipants/kits, the Group Buy is about PCBs only

Approximate prices (one kit = 2 PCBs, PayPal fees and 1€/kit donation to DIY audio included):

10-14 kits 36€ (made in China)
15-24 kits 30€ (made in China)
25-49 kits 32€
50-99 kits 27€
100-199 kits 23€
200 or more 21€

Shipping prices will be (for each kit, for 2 kits add 1€, more than 2 will be calculated):

Italy 7€
Europe 10€
Rest of the world apart Oceania 13€
Oceania 14€

PCBs (circa 12 x 10.5 cm) will be blue, 2mm tick, 2 Oz/70um copper, gold plated, made in Italy (from 25 kits and up).

One transformer 160VA-300VA will be needed for each board (monoblock design)

BOM cost is around 76€ per board (premium industrial BOM) which can be lowered to 52€ (On a budget BOM).

A complete amp (premium industrial BOM) will cost around 450€ and up.

If interested please PM me your PayPal associated email address and fill your nickname, country (2 letter code) and number of kits on the Google Spreadsheet

Mauro Penasa for his great design and kind permission
LinuxGuru for his help on new compensation
Luka for the LM318 PS initial design
KSTR for the new C9, R10 arrangement.
Soongsc, Marce, Sebaastian, KSTR and Metal for help on PCB design
BMCBob for all support, tests and reviews

Images of boards from previous GB (made in Italy):

skunark 28th April 2013 09:39 PM

The link to your spreadsheet is read-only, but i'm in for two.


ClaveFremen 28th April 2013 10:48 PM


Originally Posted by skunark (
The link to your spreadsheet is read-only, but i'm in for two.

Now the spreadsheet should be writeable.

You mean 2 kits (4 PCBs) or 2 PCBs (1 kit)?

skunark 28th April 2013 11:08 PM

2 kits, thanks for adding me to the spreadsheet.

pinnocchio 29th April 2013 06:33 PM

I'm in for another kit so long we reach the same price point. :D


ClaveFremen 3rd May 2013 12:21 AM

In case partecipants will not be enough to have a good price from the Italian manifacturer boards will be made by MakePCB (China) or similar to lower cost.

1543 3rd May 2013 09:03 AM

Come on guys, no more diyaudio members interested to build the My_Ref Fremen Edition?

Mauros standard MyRefC is already a good amplifier and a lot of diyaudio members spent time and share their knowledge and experience to improve this fine amp.

Find in thread linked below measurements of My_Ref FE prototype from member KSTR:

Post 3064216


ClaveFremen 3rd May 2013 12:09 PM

Low numbers prices
Just added approximate prices for a low number GB (PCBs made in China by PCBCART):

10-14 kits 36€ (made in China)
15-24 kits 30€ (made in China)

The exact price will be calculated upon the exact number of boards, from 25 kits and up I prefer to use the same excellent local supplier as previous GBs.

AndrewT 3rd May 2013 12:19 PM

are you going to look at improving the relay delay and relay triggering?
are you going to look at the PSU grounding?

I'm not sure if those were the only items I had made adverse comment on?

bcmbob 3rd May 2013 03:06 PM

Hi Andrew,

I'm aware that you don't care much to repeat yourself, but could you be more specific? I'm not sure what is proposed as a solution to what may or may not be a real time performance issue. I reported a "ground hum" factor on one of my builds with some associated equipment, but am not sure that is what you are referring to.

IMO, a more detailed explanation and potential solution on both of your questions would be helpful and warrant some further investigation.

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