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My_Ref Fremen Edition GB (11th run)
My_Ref Fremen Edition GB (11th run)
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Old 31st October 2017, 11:47 PM   #1
ClaveFremen is offline ClaveFremen  Italy
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My_Ref Fremen Edition GB (11th run)
Default My_Ref Fremen Edition GB (11th run)

Preface

This is the first GB from Mauro Penasa (the original My_Ref Designer) death.

Mauro, thanks again for your priceless contribution to the DIY community, rest in peace.

To keep prices lower in case of a small number of participants, up to 20 kits, PCBs will be produced in China.

From 20 kits and up PCBs will be produced in Italy as in previous GBs.

There will be, for whom is afraid of SMD soldering, the option for boards with SMD parts already hand-soldered with ROHS silver solder, thoroughly cleaned and visually inspected for 50 more per kit, including SMD parts (a 20 value).

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 (please leave blank the 'PP account sent' column, I'll fill it so you have a feedback that I've received your data)

November, 19 price will be fixed and I'll start sending PayPal Invoices, all payments are due by November, 26.

Until PCB order from manifaturer is done it will be possible to partecipate to the GB

Boards will be ordered by November, 26 and should be in my hands in 15-20 days, then packaged and shipped in a week or so.
Remember to sign-up on the Google Spreadsheet to partecipate!

Now the usual (updated) opener
:

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.

Click the image to open in full size.

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

KSTR's measurements on beta boards (final boards measured a tiny bit better but almost the same performance):

Click the image to open in full size.

7th run boards measures even better (Measure by JosephK):

Click the image to open in full size.

Distortion goes down ten times Vs. Beta (and previous) Boards

On my Google Drive you'll find:

Schematic
Schematic (PS)
BOM
Build Tutorial

And a YouTube video on SMD soldering of FE modules.

Mouser shared projects (order 2, each project is for a SINGLE board):
Industrial BOM
Industrial BOM without SMD parts
Industrial BOM + Evo A Mod
Industrial BOM + Evo A Mod without SMD parts
On a budget BOM

Actual price will depend on number of partecipants/kits, the Group Buy is about PCBs only, with an option for SMD populated ones.

Approximate price is 25-27/Kit (one kit = 2 PCBs, PayPal fees and 1/kit donation to DIY audio included):

Actual price will be calculated and fixed before ordering boards and it will lower as kits numbers goes up.

Shipping prices will be (up to 2 kits, more than 2 will be calculated):

Italy 9
Europe 13,5
Rest of the world apart Oceania 17,5
Oceania 18,5

PCBs (circa 12 x 10.5 cm) will be blue, 2mm tick, 2 Oz/70um copper, gold plated, made in Italy (from 25 kits) or in China (up to 24 kits).

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

BOM cost is around 67 per board (premium industrial BOM) which can be lowered to 53 (On a budget BOM).

Build a complete amp (premium industrial BOM with case, connectors, cabling, transformers etc.) will cost around 400 and up.

Greetings:
Mauro Penasa (R.I.P.) 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
JosephK for his measurements and advice on further reducing distortion.

Images of boards from the 7th GB:

Click the image to open in full size.
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Old 2nd November 2017, 10:40 PM   #2
ClaveFremen is offline ClaveFremen  Italy
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My_Ref Fremen Edition GB (11th run)
Weird... in the last weeks several members asked for boards and now no one jumps in?
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Old 3rd November 2017, 07:30 AM   #3
lucylu is offline lucylu  England
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Jumped ,,always missed the first 10 GB
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Old 3rd November 2017, 09:14 AM   #4
ClaveFremen is offline ClaveFremen  Italy
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My_Ref Fremen Edition GB (11th run)
John and Davor, welcome on board

To all participants, when you add your name to the spreadsheet also post here so to keep the thread visible, more kits, lower price.
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Old 3rd November 2017, 04:42 PM   #5
jwjarch is offline jwjarch  United States
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Location: San Leandro, CA
Count me in for 2 more kits (4 boards) Dario! Thank you!
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Old 3rd November 2017, 07:07 PM   #6
ClaveFremen is offline ClaveFremen  Italy
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My_Ref Fremen Edition GB (11th run)
Welcome on board Jon!

pluplog you should send me via PM your email address associated with PayPal.
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Old 6th November 2017, 12:23 PM   #7
ClaveFremen is offline ClaveFremen  Italy
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My_Ref Fremen Edition GB (11th run)
Quote:
Originally Posted by ClaveFremen View Post
pluplog you should send me via PM your email address associated with PayPal.
Still waiting...
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ClaveFremen "Bailando Salsa en el Sietch" - For My_Ref FE 12th GB extra boards PM me.
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Old 9th November 2017, 08:13 AM   #8
ClaveFremen is offline ClaveFremen  Italy
Reality first!
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Join Date: May 2005
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My_Ref Fremen Edition GB (11th run)
We're stuck at 5 (confirmed) kits, to have a decent price we should arrive at least to 10 kits.

If you're interested please jump in.
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Old 9th November 2017, 06:17 PM   #9
stellarelephant is offline stellarelephant  United States
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I am interested in building a GC of some sort. I would like to drive mine with a Class A preamp. In this scenario, what sonic advantages might the My_Ref Fremen hold over the much simpler original GC circuits? If possible, some comparisons would be useful...I am more interested in subjective listening impressions than THD figures. Surely this has been documented previously but there are so many GC threads at this point my head is spinning. Thanks for humoring a newcomer.
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Old 9th November 2017, 08:17 PM   #10
ClaveFremen is offline ClaveFremen  Italy
Reality first!
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Location: Milan, Italy
My_Ref Fremen Edition GB (11th run)
Quote:
Originally Posted by stellarelephant View Post
I am interested in building a GC of some sort. I would like to drive mine with a Class A preamp. In this scenario, what sonic advantages might the My_Ref Fremen hold over the much simpler original GC circuits?
Mmh, how I can explain the difference... Simply Night and Day, literally!

Jokes apart the My_Ref is a nested feedback curent pumping amp, way better than any plain Gainclone.

It has a tight grip on speakers, plenty of detail without harshness, wide and deep soundstage and a pretty transparent timbre.

Quote:
Originally Posted by stellarelephant View Post
If possible, some comparisons would be useful...I am more interested in subjective listening impressions than THD figures.
THD figures simply are tools to prove that the homework is done, they don't tell you how it will sound.

The My_Ref FE simply sound fantastic!

I will try to post some links of builders reviews.
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