My_Ref Fremen Edition - Build thread and tutorial

Nichicon PW

After mounting MLythic AGs a slight low freq hardness became apparent in my setup.

Since I know very well how good are AGs the problem should have been elsewhere, in some new part in BOM so, after some investigation I've started removing Nichicon PWs in my DCB1 and new DAC..much better!

Also using KZs or Black Gate PK in C9 in place of Cerafines the problem seem to disappear.

When PW are only in the My_Ref togheter with Cerafines and AGs the problem is neglegible and I've never noticed it with Vishay BC PMG SI or KZs in C9.

I don't consider it a real problem, particularly if AGs are not used togheter with Cerafines, so PWs are still in BOM.

Nevertheless I'll try to find an even better cap for C1, C2 that matches the base BOM and all upgrades... Suggestions are welcome ;)

In the very unlikely event any of you hear the problem and want to use Cerafines in C9 Panasonic FM will be a nice alternative for C1 and C2.

Feedback from the early builders is also welcome :)
 
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Nichicon PW/Elna Cerafine/Mundorf MLythic AG combination

I'm re-reading my last post and it's not perfectly clear even to me... :D

I'll re-phrase it:

When using Mundorf AGs and Cerafines in C9 a slight bass hardness could appear if other gear in your setup don't match well.

The problem is Nichicon PW that can sound that way in certain conditions but quite all upgrade combinations will work very well, unique exception so far are Cerafines in C9 when also AGs are present.

I'll try other caps and if I will find a cap for C1 and C2 that sounds same or better and matches well also with Cerafines, PW will go.

In other words:

With the new BOM Cerafines will work great in most combinations but with AGs it's possible a slight bass hardness.

Is it more clear? :rolleyes:

I hope so ;)
 
Another DAC/OpAmp problem?

It's possible that the hardness problem I've experienced was, like the KZ one, due to a mismatch between the amp and the opamp used on my new DAC...

In the last 10 days I was using a JRC NE5534DD, not bad I must say, today I've tried a NOS Signetics NE5534A, way better.

I've tried to put back the Cerafine in C9, problem almost disappeared... :eek:

So I've just made an opamp rolling session on the DAC... the problem seems to be there only with the JRC NE5534DD :mad:

Is it possible that the amp, along with the DCB1, is so transparent that every opamp's defect became so apparent? :rolleyes::D

This week end I should be able to finalize upgrades recommendations and their priorities.
 
"I have this picture in my mind of Bob sitting there, soldering iron in hand, poised over his workbench, saying over and over in a low tone, "I'm ready, I'm ready,.....

Jac

PS
Hey Bob, can I interest you in a vacuum tube phono pre-amp project? Just kidding."


Hi Jac :)

You got it pretty close. I now have an excuse to upgrade my soldering station. I've been using a $19 special from PE which lasts ~ 1Yr and I've gone through two. Now's the time to go pro.:D

I know you were kidding about the pre, but FWIW, I tried several nice pieces over the years but am running without one. I settled on mainlining a S/PDIF link from a music server direct to a JP/Subbu DAC that feeds directly to the FEs. Both the dac and FEs have protection. That eliminates a stage and produces very clean and pure sound . No tone control unless I switch on the excellent filters in the Jriver MC software. Volume can be adjusted via the computer, phone or iPad. I might experiment with preamps again after this next FE build, but this configuration will be hard to beat.

Later.........
 
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Final Upgrades BOM and priorities

It's been a long journey but at last... :)

Let's start with upgrades priorities:

  1. C9 (Cerafine)
  2. R12 (Z-Foil)
  3. C30, C32, C12 (Amtrans AMCH)
  4. C13 (Mundorf Supreme)
  5. R7 and R10 (Z-Foil)
  6. C101, C201 (Mundorf MLythic AG)
  7. R37 (Z-Foil)
Upgrades 1-4 should be considered the Audiophile Base BOM, while 5-7 for a cost no object build.

Each upgrade leads to a significant perceived performance increase and when all applied will raise the bar to another category of performance.

In this regards the Fremen Edition could be considered a 'scalable' amplifier, more better components you will put in better it will sound. ;)

1 - Cerafine in C9

I consider this upgrade MANDATORY!

KZ will sound good but it will not sound how a My_Ref Fremen Edition is supposed to.

What you can expect:

  • A more life-like timbre
  • A much more open, dynamic and detailed sound
  • An higher harmonic content
Note:
The higher harmonic content means less loss, NOT added distortion!
Remember that I compare them to an absolute reference, in this case a shorted C9 (only for test purposes, it MUST be populated, DC offset will be 240mV!!!).

Black Gates PK and Standard are good alternatives, PK will sound very similar to Cerafine but slightly warmer and cleaner than life, Standard similar to PK but with less harmonic content and detail.

2 Vishay VAR/Texas Components TX2575/Charcroft Electronics CAR in R12

I strongly suggest this update

What you can expect:

  • A more neutral and life-like timbre
  • More detail and deeper soundstage
  • An higher harmonic content
  • Cleaner sound
3 - Amtrans AMCH in C30, C32, C12

Amtrans AMCH are a worthwhile improvement over Wima FKP2.

What you can expect:

  • A more life-like timbre
  • An higher harmonic content
  • Cleaner sound
Note:
The higher harmonic content means less loss, NOT added distortion!
Remember that I compare them to an absolute reference, in this case an unpopulated C12 (only for test purposes, it MUST be populated).

attention.gif
Attention!

During revision I've determined that C32 orientation indicated on PCB (up to rev. 1.6) is not the optimal one, C32 should be mounted reversed.
The upcoming updated build tutorial will highlight this problem.

4 - Mundorf MCAP Supreme in R13

Mundorf Supreme is a worthwhile improvement over CDE940C.
CDE 940 is an excellent base cap, though, and not a problem at all.

What you can expect:
  • Bigger soundstage and contrast
  • An higher harmonic content
  • Cleaner sound
  • More engaging
Both are quite transparent I would say 95% of the control (plain wire) for 940C and 98% for the Supreme.

Note:
The higher harmonic content means less loss, NOT added distortion!
Remember that I compare them to an absolute reference, in this case C13 populated with a piece of copper wire (only for test purposes, C13 MUST be populated to protect your loudpeakers from source/preamp failures).

attention.gif
Attention!

During revision I've determined that CDE940C orientation indicated in a previous post is not the optimal one, CDE940C should be mounted reversed.

Supreme orientation is correct.

The upcoming updated build tutorial pic will be correct.

5 - Vishay VAR/Texas Components TX2575/Charcroft Electronics CAR in R7 and R10

I strongly suggest to upgrade them together, if not possibile R7 is more important.

What you can expect:

  • A more neutral and life-like timbre
  • More detail and deeper soundstage
  • An higher harmonic content
  • Cleaner sound
Z-Foils advantage increases as more of them are used, see orientation here.


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6 - Mundorf MLythic AG in C101, C201

Mundorf AGs are a worthwhile improvement over Vishay/BC PMG-SIs.

Vishay/BC PMG-SI is an excellent base cap, though, and not a problem at all.

What you can expect:

  • Blacker background and more contrast/focus
  • An higher harmonic content
  • Cleaner sound
  • Fuller and deeper bass
The change after the upgrade is not small, pretty evident but AGs comes at over 4x the PMG-SI cost.

Is it worth it?

IMHO, absolutely yes

7 - Vishay VAR/Texas Components TX2575/Charcroft Electronics CAR in R37

What you can expect:

  • A more neutral and life-like timbre
  • More detail and deeper soundstage
  • An higher harmonic content
  • Cleaner sound
Z-Foils advantage increases as more of them are used, see orientation here.

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It's been a long journey but at last... :)

Let's start with upgrades priorities:

  1. C9 (Cerafine)
  2. R12 (Z-Foil)
  3. C30, C32, C12 (Amtrans AMCH)
  4. C13 (Mundorf Supreme)
  5. R7 and R10 (Z-Foil)
  6. C101, C201 (Mundorf MLythic AG)
  7. R37 (Z-Foil)
Upgrades 1-4 should be considered the Audiophile Base BOM, while 5-7 for a cost no object build.

Each upgrade leads to a significant perceived performance increase and when all applied will raise the bar to another category of performance.

In this regards the Fremen Edition could be considered a 'scalable' amplifier, more better components you will put in better it will sound. ;)

Did you update the BOM? If yes, only 1-4 or also 5-7?

Thanks
 
Did you update the BOM? If yes, only 1-4 or also 5-7?

Thanks

On the Google Drive's BOM 1-4 and 6 are highlighted with bold chars, while 5 and 7 are indicated as options in notes, since the 1.6 BOM release.

Since long time passed from original FE's BOM release I've re-checked all previous upgrades against new BOM and tried some new.
 
7 - Vishay VAR/Texas Components TX2575/Charcroft Electronics CAR in R37

What you can expect:

  • A more neutral and life-like timbre
  • More detail and deeper soundstage
  • An higher harmonic content
  • Cleaner sound
Z-Foils advantage increases as more of them are used, see orientation here.

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Hello,
in my v1.5 boards there are no through hole pads for R37, just smd pads.
How did you mount a z-foil resistor in R37? I can't see enough in the pics...
 
I just ordered the Rev A mod stuff that was in the BOM. Thought was parts quality not certain parts left out.

Thanks for spotting that. What do you suggest? Rev A mod or not?

I use Rev A mod since 2013, guess what? ;)

Rev A mod has no C10 and R39 and R3 is 0.33R instead of 0.47R.

It's a different compensation Penasa made for the My_Evo (Evolution) that is compatible with the Fremen Edition.

  • Improved stability on capacitive loads (the system now accepts the presence of any capacity directly at the output terminals without stability limits)
  • Changing the decay of the damping factor versus frequency. The Rev A introduces more damping at medium and low frequencies.
  • Change of the DC operating point active network integration. The high-pass third-order granted (Q> 0.7) is replaced with a previous "double-first order", or by an active integrator that works with the more classic high pass time constants next to the DC (> 0.1Hz) represented by the input coupling capacitor
  • Change wiring of the chassis grounds ie chassis directly connected with the power ground sheet and no earth connection. (already recommended on FE build tutorial)
  • Change of some wiring (pin 7 LM3886) (already implemented on FE boards)


in my v1.5 boards there are no through hole pads for R37, just smd pads.
How did you mount a z-foil resistor in R37? I can't see enough in the pics...

Same here, i think you can bend the legs into a small 'L' and solder that to the smd pads on the bottom of the board.

v1.5 boards have only SMD pads for R37 and previous ones also for R7.

But it's easy if you have a dremel or similar with a 0.8-1mm drill bit to make holes from the bottom side of the boards then you can mount through hole resistors.

No planes or traces are present over those smd pads on the upper side.

Just make attention to R7 which is near the 0V ground plane, you simply have to be precise.

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v1.5 boards have only SMD pads for R37 and previous ones also for R7.

But it's easy if you have a dremel or similar with a 0.8-1mm drill bit to make holes from the bottom side of the boards then you can mount through hole resistors.

No planes or traces are present over those smd pads on the upper side.

Just make attention to R7 which is near the 0V ground plane, you simply have to be precise.

Thank you! I'll try...:xfingers:
But... there's no risk for the Dremel bit to tear away smd pads on the bottom?
Maybe could i solder, on the upper side, z-foil legs to C30 lower pad and LM3886 second pin of the lower row? (see red circles in the following pic)
Z-foil R37 solder.jpg
I had no problem with R7, as holes are on both surfaces: i just had to remove solder inside smd pads holes on the bottom, using my desoldering gun.
 
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Thank you! I'll try...:xfingers:

You're welcome :)

But... there's no risk for the Dremel bit to tear away smd pads on the bottom?

I don't think so, those pads are part of a trace...

Obviously you must take care, use moderate to low pressure and rotational speed.

For more precision and safety you can use the smallest drill bit you have and then repeat drilling with increasingly larger drill bits until you have a hole large enough to let leads pass.

Using a powerfull drill with percussion enabled is not advisable, though... ;) :D :spin:

Maybe could i solder, on the upper side, z-foil legs to C30 lower pad and LM3886 second pin of the lower row?

you will have longer leads and the added inductance could be a problem there...it's a delicate position, that net is critical for stability.

I had no problem with R7, as holes are on both surfaces: i just had to remove solder inside smd pads holes on the bottom, using my desoldering gun.

I know, for R7 I was targeting pre v1.5 owners.
 
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