That AMCG looks interesting.
I still like the Mundorf Supreme, but I haven't had a chance to compare the auricap.
Yes. C9 is still a major influence on sound character.
Your BOM has a lot of differences from the official BOM. I notice the small MKT caps, for example. Just so you know, this group is very component specific and, especially Dario, has spent lots of time and money comparing component options. Building the amp with correct value components, but not at all related to the specified components will, for most of us, put you in a place where we don't know how the amp will sound. IMHO it won't sound at all like it was intended too. That goes all the way down to diodes, etc. I know that there are a lot of people that believe that component choice doesn't matter and I respect their opinion. But that hasn't been my experience. And we aren't about snake oil and expensive. The industrial BOM is quite reasonably priced and still sounds very good.
Anyway, C9 will be the most important component to try.
Jac
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Hi Dario, sorry I am not sure what you mean. I would add that the Russ White board has all the component values screen printed on it.
I think I get it. You are talking about a Russ White (TP or Twisted Pear) board and built it with the BOM of that time.
We thought you were asking questions about a Fremen Edition build, which is the subject of this thread. If that is the case, I only came in when the Fremen Edition was being developed, so I don't know anything about the Russ White board and withdraw all of my comments. I'm guessing that the Russ White board, which is a My_Ref, would still be very responsive to C9, but that is just a guess.
Jac
We thought you were asking questions about a Fremen Edition build, which is the subject of this thread. If that is the case, I only came in when the Fremen Edition was being developed, so I don't know anything about the Russ White board and withdraw all of my comments. I'm guessing that the Russ White board, which is a My_Ref, would still be very responsive to C9, but that is just a guess.
Jac
LM318 power supply voltage.
I guess I hadn't paid attention. If I am reading correctly, Mauro powered the LM318 with +/- 12V. Dario increased that to 14V. Reading the datasheet, the LM318 is capable of +/- 20V and the datasheet measurements were at 18.
Is there a reason why you couldn't increase the voltage to, for example, 18V by changing the zener? I am asking because a friend has an FE amp, is building a balanced line receiver, and is considering powering it from C102,C202. His balanced line receiver wants higher voltage. I have explained the risks of oscillation, but it seems like it would be worth trying.
Thanks
Jac
I guess I hadn't paid attention. If I am reading correctly, Mauro powered the LM318 with +/- 12V. Dario increased that to 14V. Reading the datasheet, the LM318 is capable of +/- 20V and the datasheet measurements were at 18.
Is there a reason why you couldn't increase the voltage to, for example, 18V by changing the zener? I am asking because a friend has an FE amp, is building a balanced line receiver, and is considering powering it from C102,C202. His balanced line receiver wants higher voltage. I have explained the risks of oscillation, but it seems like it would be worth trying.
Thanks
Jac
As I have just mentioned it elsewhere, please do not chsnge the PS value in the TP myref board.
That version did not have the EVO/ FE style clipping limiter.
Mauro, on purpose, had limited the PS to the opamp, so it does the output limiting in the driving phase, before the LM3886 would enter clipping.
In the later versions, with clipper, one 'could' experiment with PS, but the lm318 does become more instable (it's already a high speed chip, not really audio) - - so not by accident that Mauro had stopped at 14V (in the EVO). And Dario (in the FE).
All the best, George
Ps. : i have elevated to +_18V, in my ampli (EVO) but only because I could, with OPA828...
That version did not have the EVO/ FE style clipping limiter.
Mauro, on purpose, had limited the PS to the opamp, so it does the output limiting in the driving phase, before the LM3886 would enter clipping.
In the later versions, with clipper, one 'could' experiment with PS, but the lm318 does become more instable (it's already a high speed chip, not really audio) - - so not by accident that Mauro had stopped at 14V (in the EVO). And Dario (in the FE).
All the best, George
Ps. : i have elevated to +_18V, in my ampli (EVO) but only because I could, with OPA828...
Ok, now I get it.
While we can help since the two amps are strictly related you're on the wrong thread... the right one is this: The new "My Ref" Rev C thread
Please post there, I'll give you my suggestions.
Hi i made a thread here about your pcb. I was hoping if you could lend me your insight. Thank you.
https://www.diyaudio.com/forums/power-supplies/369648-slitted-ground-plane.html#post6580396
https://www.diyaudio.com/forums/power-supplies/369648-slitted-ground-plane.html#post6580396
Hi everyone,
Now received my My_Ref FE pcb's, started to assemble components and realise I only ordered 2 of R101 & R201 Vishay Dale metal film 50 ohm resistors (i.e., I should have ordered 4 total, 2 for each board, of course!). Doh!
Everywhere now seems out of stock, long wait times etc., so before I go ahead and place a back order and need to wait some weeks (annoying!) does anyone out there have a couple of these resistors spare by any chance, that I could gratefully purchase from you and (hopefully) obtain a bit sooner!
Thanks, in anticipation!
Now received my My_Ref FE pcb's, started to assemble components and realise I only ordered 2 of R101 & R201 Vishay Dale metal film 50 ohm resistors (i.e., I should have ordered 4 total, 2 for each board, of course!). Doh!
Everywhere now seems out of stock, long wait times etc., so before I go ahead and place a back order and need to wait some weeks (annoying!) does anyone out there have a couple of these resistors spare by any chance, that I could gratefully purchase from you and (hopefully) obtain a bit sooner!
Thanks, in anticipation!
Hi Richard,
Someone may disagree with me, but you could probably go ahead with pretty much any resistor of the right value in that location and not pay a big price. Those resistors are just used in the constant current source of the regulator. You could build with resistors on hand and replace them later.
Jac
Someone may disagree with me, but you could probably go ahead with pretty much any resistor of the right value in that location and not pay a big price. Those resistors are just used in the constant current source of the regulator. You could build with resistors on hand and replace them later.
Jac
Here I am, Jac...
I disagree, trust me or not those resistors are easily audible and I suggest to stick to the BOM, the RN55 are good price/performance parts in that position.
Thanks for the info Dario - I've now ordered Vishays from Mouser anyway and looks like they're being shipped already ..... having waited this long to get started I don't mind waiting a little while longer to get the correct items!
Good news - I've been able to complete one channel that I did have the correct resistors for, all working well so far - DC offset ~ 7mV on first turn on (same whether I/P shorted or not - is that normal, I expected lower DC when I/P shorted?).
Won't 'burn it in' just yet - I'll wait until both channels are completed and them run them both at the same time so I can compare voltages as they settle down.
Best regards,
Good news - I've been able to complete one channel that I did have the correct resistors for, all working well so far - DC offset ~ 7mV on first turn on (same whether I/P shorted or not - is that normal, I expected lower DC when I/P shorted?).
Won't 'burn it in' just yet - I'll wait until both channels are completed and them run them both at the same time so I can compare voltages as they settle down.
Best regards,
Dario, I won’t argue with your choice of RN55s in most signal path areas (they are dependable and imbue an audible accuracy) but at the positions mentioned (R101&201) since they set the voltage output of the LM317s couldn’t it be more likely that it’s the tolerance of the RN55s (~0.1%) that are playing a role in possibly affecting the sound? If you picked another brand that had a 0.1% tolerance or hand matched 4 resistors (with 1% accuracy) for exactly 50R one may not hear a difference. This is just a theoretical question.
I’d still use Dales....
Regards,
Pete
Hi Pete,
no, it's not tolerance, I've compared, among others, also PTF56 0.1% and there was a distinct difference in the sound signature, the same one you can hear on the signal path.
At the same time tolerance (and TC) have a role, 0.1% low TC RN55 sounds more neutral and detailed than 1% 50ppm ones.