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My_Ref Fremen Edition GB (12th run)
My_Ref Fremen Edition GB (12th run)
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Old 12th April 2018, 06:31 PM   #1
ClaveFremen is offline ClaveFremen  Italy
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Join Date: May 2005
Location: Milan, Italy
My_Ref Fremen Edition GB (12th run)
Default My_Ref Fremen Edition GB (12th run)

Preface

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)

May, 6 price will be fixed and I'll start sending PayPal Invoices, all payments are due by May, 12.

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

Boards will be ordered by May, 13 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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ClaveFremen "Bailando Salsa en el Sietch" - For My_Ref FE 12th GB extra boards PM me.

Last edited by ClaveFremen; 14th May 2018 at 10:11 PM.
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Old 13th April 2018, 11:45 PM   #2
ClaveFremen is offline ClaveFremen  Italy
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My_Ref Fremen Edition GB (12th run)
Thanks to particpants that booked in advance we're already at 12 kits.

Whoever is interested jump-in to lower boards price.
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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 13th April 2018, 11:53 PM   #3
tomchr is offline tomchr  Canada
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Are my (promised) measurements of Rev. 1.6 still relevant then?

Tom
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Old 14th April 2018, 12:00 AM   #4
ClaveFremen is offline ClaveFremen  Italy
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My_Ref Fremen Edition GB (12th run)
Quote:
Originally Posted by tomchr View Post
Are my (promised) measurements of Rev. 1.6 still relevant then?
Hi Tom,

only difference from 1.6 boards is C21 removal and C9 arrangement is a bit more compact, should make little or no difference.

So, absolutely, your measurements will be relevant.
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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 14th April 2018, 12:07 AM   #5
tomchr is offline tomchr  Canada
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Cool. Thanks for confirming. Is this GB for Rev. 1.7 of the board then? Or Rev. 1.6? I have Rev. 1.6 and a while back you mentioned a Rev. 1.7 that was basically silk screen tweaks as far as I recall.

I wasn't quite sure given your intro. I guess the changes mentioned in Post #1 are the changes from the original MyRef circuit.

Tom
__________________
Modulus-686: 240W/8Ω @ <0.00025% THD. Modulus-86: 40W/8Ω @ 0.000054% THD. DG300B & Other Tube Circuits.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right

Last edited by tomchr; 14th April 2018 at 12:10 AM.
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Old 14th April 2018, 12:15 AM   #6
tomchr is offline tomchr  Canada
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Double-checked the documentation. Looks like there's a Rev. 1.7, so I'm assuming that's what you'll run for this GB. Did you implement the fix for the input ground mentioned on Page 7 of the Tutorial .pdf?

Tom
__________________
Modulus-686: 240W/8Ω @ <0.00025% THD. Modulus-86: 40W/8Ω @ 0.000054% THD. DG300B & Other Tube Circuits.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
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Old 14th April 2018, 05:47 AM   #7
ClaveFremen is offline ClaveFremen  Italy
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Join Date: May 2005
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My_Ref Fremen Edition GB (12th run)
Default My_Ref Fremen Edition GB (12th run)

Quote:
Originally Posted by tomchr View Post
Cool. Thanks for confirming. Is this GB for Rev. 1.7 of the board then? Or Rev. 1.6? I have Rev. 1.6 and a while back you mentioned a Rev. 1.7 that was basically silk screen tweaks as far as I recall.
Youre welcome.

Actual version is 1.72, from a couple of GBs.

Quote:
Originally Posted by tomchr View Post
I wasn't quite sure given your intro. I guess the changes mentioned in Post #1 are the changes from the original MyRef circuit.

Exactly
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ClaveFremen "Bailando Salsa en el Sietch" - For My_Ref FE 12th GB extra boards PM me.

Last edited by ClaveFremen; 14th April 2018 at 05:50 AM.
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Old 14th April 2018, 05:49 AM   #8
ClaveFremen is offline ClaveFremen  Italy
Reality first!
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Join Date: May 2005
Location: Milan, Italy
My_Ref Fremen Edition GB (12th run)
Quote:
Originally Posted by tomchr View Post
Double-checked the documentation. Looks like there's a Rev. 1.7, so I'm assuming that's what you'll run for this GB. Did you implement the fix for the input ground mentioned on Page 7 of the Tutorial .pdf?

Tom

Revision 1.72 is the 1.7 with the input ground problem fixed.
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Old 15th April 2018, 05:22 PM   #9
lisoformio is offline lisoformio  Italy
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Is it possible to join the GB for one PCB only?
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Old 15th April 2018, 06:08 PM   #10
ClaveFremen is offline ClaveFremen  Italy
Reality first!
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Join Date: May 2005
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My_Ref Fremen Edition GB (12th run)
Quote:
Originally Posted by lisoformio View Post
Is it possible to join the GB for one PCB only?
Sure, no problem.

What's the use for a single PCB, BTW?
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