My_Ref Fremen Edition - Build thread and tutorial

Jac, I think that phenomenon is nearly universal to audio equipment, and hardly specific to the type of resistor employed in any given circuit. A long, long time ago, it was agreed by most builders of the MyRef amps that they sounded best after being powered for some indeterminate time. I know mine do, so I leave them on constantly since power consumption at idle is truly insignificant.

Regarding C13 selection: there have been numerous changes to the BOM over the years. Dario listens so carefully and tries so many different types that he can't seem to make a definite choice because there is no perfect part. I have also experimented with plenty of different brands at many levels of cost. It only confirms my premise that C13 affects the amp's sound more than any other part. Changing any other element in one's system will also make the sonic qualities of C13 less or more synergistic. The Mundorf capacitors, at every level of price and type of construction, are typically on the bright side, tilting the entire frequency spectrum upward. This gives a very detailed and spacious sound, but, in my opinion, somewhat artificially "hi-fi." Many people find this attractive in their system.

It really is a personal choice, and I respectfully submit that even Dario isn't qualified to prescribe exactly which capacitor will sound best in your system. This is diyAudio, after all. Use his selection as a starting point, but you need to experiment on your own and share the results with us.

The ones I can remember, in ascending order of my preference:
Kemet polypro that came with my first MyRef group buy
Jensen polystyrene/aluminum foil
Obbligato Gold
Bennic XPP
Clarity Cap SA
Mundorf Silver/Oil
Sonicap Gen I
Fostex copper/tin foil
Audyn True Copper
Jupiter Copper Foil/paper and wax


Peace,
Tom E
 
Last edited:
Dear Jac,

I think there can be something valid, in your observation.
My very first encounter with IH left me perplexed.. With that same kind of sensation.
And that was with respect to the ATE wirewound resistors.
So yes, there is a slight hint of edge. Then, As Tom noted, also for me the first some (30?) minutes is in the dark - it's since a long time that I do not listen with attention right after first turn on. Even more, that initial warm up means also the rest in my case, dac etc which is even worse.. Though it's not that big a difference, not like it starts like sh... t.

Reassuming: it could be as you describe. I can confirm that with ATE (and probably the Wishay WW res) it is less evident. More 'musical' if You like..
But: definition, grip, consistency, deep bass etc.. are and remain trademarks of the IH.

Last point: all these are non observations, not comparable effects with respect to a change in the Dac itself..
Try to insert a D90 in the chain.. Whew... :confused:... :)
 
Last edited:
Thanks to both Tom and George for your reply. I do recognize the warm up sound change in the original FE. This seems a bit more, although I could be imagining it. As for leaving it on all the time, I feel bad about leaving one dac and 3 RPi's on all the time.

In the end, it as George says, a small difference, much smaller than a change in dac.

As for the T90, I'm told that the engineers at Topping only look at measurements, they never listen to their designs.

Tom,

Regarding C13, I agree that it is very influential in the sound of the FE. I like to look at it as a synergy issue. For example, I used a Mundorf Silver Oil at C13 for years with your Jensen at C9. In the original FE, that combination beat everything that I tried in my system. But it didn't sound good with the OPA828 and a wire for C9. In fact, I liked the Mundorf Supreme over a wire at C13. Synergy with my system and my ears.

Heck, I'm still weird enough to like the Russian K75-10 with an Amtrans bypass as a really fun, if not exactly neutral, C13.

Jac
 
A question for those of you who have played around with the Isabellenhutte resistor in R3.
(...)
I am also curious if the Mundorf's show something similar. After all, they are quite similar in construction and use the same resistance material.

While we are talking about R3, there was some early discussion about non-inductive wirewound resistors for R3, but no following comments. Can we assume that they didn't turn out to be as good a sounding choice as the Mundorf's?


Hi Jac,


sorry for the very late answer.


Are you sure you did not hear the normal warming behaviour of the My_Ref? It' pretty normal what you describe when powering up a cold amp.


In this regard I did not notice any difference between IB and Mundorf.


The wirewound I've tried (Dale RS-5) are very good and musical, a big step-up from Caddocks but IB and Mundorf are way better.
 
I wanted to know if anyone has tried wirewound resistors of the non-inductive type (Ayrton-Perry winding) which have no inductive reactance and signal loss compared to normal winding.
Resistors such as Vishay Dale NS, ATE scsn / ATE cs or Vishay Mills MRA.
Personally I have the ATE scsn that I will try ...

Ciao!
Giacinto
 

Attachments

  • Vishay Dale rsns.pdf
    200.7 KB · Views: 63
  • Vishay Mills mra.pdf
    89.1 KB · Views: 39
  • ATE-CS.pdf
    538.9 KB · Views: 59
  • ATE scsn 0R33.jpg
    ATE scsn 0R33.jpg
    400.5 KB · Views: 322
I wanted to know if anyone has tried wirewound resistors of the non-inductive type (Ayrton-Perry winding) which have no inductive reactance and signal loss compared to normal winding.
Resistors such as Vishay Dale NS, ATE scsn / ATE cs or Vishay Mills MRA.
Personally I have the ATE scsn that I will try ...


I quote myself:
The wirewound I've tried (Dale RS-5) are very good and musical, a big step-up from Caddocks but IB and Mundorf are way better.
Dale RS5 are in the same datasheet of NS5.
 
Input op-amp swap

Hello,

about the great My_ref FE, I am reading that input op-amps swap are considered stable options now (it is cited in the last group-buy thread and in the thread of comparison with other composite amps). I do see that Joseph K (George) is most active on this side.
I read all the thread of the last group-buy but I did not find specific information.


Are there building guides/help about the use of other op-amps, like OPA828, with all components?
Could someone address me to some relevant posts on the subject on this thread or others?

Thanks in advance!
Daniele



ps: I built the My_ref FE (2012 version) and I am still happy with it :)
 
I am reading that input op-amps swap are considered stable options now (it is cited in the last group-buy thread and in the thread of comparison with other composite amps). I do see that Joseph K (George) is most active on this side.


Just a disclaimer... PCBs supports use of other opamps via an additional compensation cap for people who wants to use them/experiment with but the My_Ref FE official opamp is still the LM318. ;)
 
That would be great. Thank you George!

instructions for alternative Opamp substitutes
Attention: Only Valid for 14th Group buy boards!


So, here it is a small quick effort to explain. In the photos in attach we see the two faces of the board. Red always means what NOT to be implemented, green what MUST be implemented, yellow means a variable parameter (in function of different opamp models)

What NOT to be implemented: R43 (22k); C34(27pF); C9 (220uF 35V)

What MUST be implemented: C9_byp solder jumper; C33(5pF);

What is changed depending on opamp implemented:
C32(150pF standard)

Possible choices:

C33 C32

ADA4627 5pF 150pF

OPA827 5pF 100pF

OPA828 5pF 68-75pF

Additional note: many of You will notice the C33 now suggested in all cases. It is a "safety" suggestion: as many of You know it, one can use ADA4627, OPA827 even without it.
With OPA828, it is obbligatory.
 

Attachments

  • IMG_20210207_205107.jpg
    IMG_20210207_205107.jpg
    385.5 KB · Views: 186
  • IMG_20210207_205831.jpg
    IMG_20210207_205831.jpg
    455.3 KB · Views: 181
Last edited:
Thanks, George. Nicely done. And thanks to Dario again for the C33 and C9 bypass.

Once again, the LM318 is the official opamp and these are experimental. I was just listening to my LM318 FE and it still sounds great.

If anyone is going to try the OPA828, it isn't easy finding quality caps in the 68 - 75 pF range. I tried ceramic, mica, and polystyrene and thought the polystyrene sound the best, at least in my system. Nothing fancy. Just the little silver axial industrial caps, for example:

Polystyrene (pF) Capacitor 68pF 160Vdc

or

(CPS10/68) - 68pF 630V Polystyrene Capacitor | Hifi Collective

You could also combine two smaller caps in parallel, one on top and one of the bottom of the board. I did that with a 47 pF and a 22 pF because I already had them.

Jac
 
Thanks, George. Nicely done. And thanks to Dario again for the C33 and C9 bypass.

Once again, the LM318 is the official opamp and these are experimental. I was just listening to my LM318 FE and it still sounds great.

If anyone is going to try the OPA828, it isn't easy finding quality caps in the 68 - 75 pF range. I tried ceramic, mica, and polystyrene and thought the polystyrene sound the best, at least in my system. Nothing fancy. Just the little silver axial industrial caps, for example:

Polystyrene (pF) Capacitor 68pF 160Vdc

or

(CPS10/68) - 68pF 630V Polystyrene Capacitor | Hifi Collective

You could also combine two smaller caps in parallel, one on top and one of the bottom of the board. I did that with a 47 pF and a 22 pF because I already had them.

Jac

Hi Jac and thanks for advice. What sounded bad with mica or ceramic compared to polystirene_?
Do you still use those diy SMD series paralel for R3?

Greetings,
Adrian
 
Last edited: