Found it, it's a couple of pages though... http://www.diyaudio.com/forums/chip-amps/234032-my_ref-fremen-edition-build-thread-tutorial-224.html
I think for my speakers 22v is better after reading lehmanhills reply, 94db is quite sensitive. Maybe yours are less, so 24 could be oke.
Contacted selectronics if their r-cores will be in stock anytime soon, will report back if I know more. Im quite hesitant to order the r-cores from China due to possible extra charges like VAT and customs.
Interesting link explaining differences between different kinds of transformets: Shilchar Technologies Ltd.
They too claim a higher efficiency for r-cores... No data though, would have been nice. Not trying to start a new argument about efficiency. Read the threads above, a lot has been said already and very informative.
Just like to say after building the femen with standard BOM components it sounded very good. Now after doing all of the recommended upgrades I can say this is a spectacular sounding amp.
I'd say it's taken 30 hrs to bed in again so don't expect results straight away. Definitely more detail, lower lows and string instruments sound very good. I do not seem to need as much volume anymore to achieve a level where everything sounds right. This is purely my layman's description so sorry if I'm not coming across with the right terms.
I'd say it's taken 30 hrs to bed in again so don't expect results straight away. Definitely more detail, lower lows and string instruments sound very good. I do not seem to need as much volume anymore to achieve a level where everything sounds right. This is purely my layman's description so sorry if I'm not coming across with the right terms.
lehmanhill: thanks for your explanation, that makes a lot of sense. Sensitivity of both speakers is almost the same (89 vs 90db). Since i usually listen at ~25% and never go over 50% i think i will be fine. Maybe I'll just use them for now and see if i can trade them in the future 
Wilco: awesome! thanks for finding the posts. I knew i read about it but wasn't sure in which thread they were posted. I can highly recommend the R-cores from selectronic. Very nice quality.
Wilco: awesome! thanks for finding the posts. I knew i read about it but wasn't sure in which thread they were posted. I can highly recommend the R-cores from selectronic. Very nice quality.
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Maybe I'll just use them for now and see if i can trade them in the future
Wilco: awesome! thanks for finding the posts. I knew i read about it but wasn't sure in which thread they were posted. I can highly recommend the R-cores from selectronic. Very nice quality.
Darn, they restocked them! When I was buying most parts, I ended buying from a local manifacturer... spending more than a bit more.
I still don't know Dave. If selectronics restocks them in time, I will try the 120 2x22v r-core. If not, just 225/300VA toroids. If I let them come from China, I'm afraid cost will be too high after taxes and customs.
Ghiglie: did they restock them? Can't see it, do you have the link?
Question: what compensation do you guys advise? Fe compensation or the Rev A? Correct me if I'm wrong, but rev a should measure better, higher stability and has a somewhat bigger soundstage than Fe compensation?
Ghiglie: did they restock them? Can't see it, do you have the link?
Question: what compensation do you guys advise? Fe compensation or the Rev A? Correct me if I'm wrong, but rev a should measure better, higher stability and has a somewhat bigger soundstage than Fe compensation?
Maybe it's just Naim marketing spiel, maybe not:
"Naim Electronic Design Director Steve Sells explains the thinking behind this: ‘A single large transformer has a lower impedance and so charges PSU reservoir capacitors faster than two smaller transformers. This in turn allows the mains conduction angle to be shorter, essentially allowing the PSU to be disconnected from the mains for a longer time.’"
From here:
https://www.naimaudio.com/connectio...s-dr-power-amplifiers-taking-you-inside-music
"Naim Electronic Design Director Steve Sells explains the thinking behind this: ‘A single large transformer has a lower impedance and so charges PSU reservoir capacitors faster than two smaller transformers. This in turn allows the mains conduction angle to be shorter, essentially allowing the PSU to be disconnected from the mains for a longer time.’"
From here:
https://www.naimaudio.com/connectio...s-dr-power-amplifiers-taking-you-inside-music
Seems to be avaialble:
Transformateur R-core 120VA - 2 x 24V - R-CORE pour châssis
Not sure whether or not to try these as I already have a pair of suitable 160VA toroids.
This second quote actually sounds right and seems to me to be scientifically based.
Whereas your first statement sounds made up.
I'm not sure how to ask a simple question on this forum without the pedants attacking.
Can anyone recommend a transformer type and/or rating based on subjective sound quality?
Thanx! Looked on the Belgium website, they didn't have them in stock, a week ago they didn't have them in France also. The 300va are big beasts Dave... 3.1 kg. And maybe a bit overkill. But some in the forum say you need a little bit more. Maybe just try and update later?
Will 2x21 be enough for 4 ohm speakers? Advise is 22, 21 should be ok, shouldn't it?