The differences are solely in the compensation and stability components, and can be fitted on Rev C V1.2, 1.3 and 1.4 boards.
For Rev C:
C10=22pF
C32=150pF
C34=10pF
R42=47R (can be omitted, i.e. shorted)
For Rev E:
C10=27pF..33pF (higher is less stable) 2% Silver Mica (preferred)
C32 =150pF..330pF (higher is more stable) FKP2 (preferred)
C34=47pF..100pF (higher is more stable) 2-5% Silver Mica (preferred)
R42=0
With 27/330/100, the sonic impressions of Rev E are:
1) Immersive, palpable, forward soundstage
2) Taut, tight, percussive mid-bass definition and dynamics
3) Slightly edgier upper mids
Simulation indicates slightly higher THD20 (~6 dB) for Rev E over Rev C, but mostly H2 (i.e. warmer sonics). Edgier upper-mids of Rev E can be tamed with the LF01 Class-A hybrid/discrete opamp module, without loss of other sonic benefits.
edgier upper mid could be contributed by the material choice of silver micas. I certainly found them bright when i had them swapped in place of c10/32 (original rev C value) though again, with a sharper imaging and more athletic transients.
was any alternative caps tried for c10/34 in rev E specification?
i could actually order some copper wirewound types as seen here ÈÕ¾« ¶¥¼¶ÍĤ ÌìÁú¶¨ÖÆ 100pF 125V OFC 7x15 ö¦ÉùµçÈÝ-ÌÔ±¦Íø
was any alternative caps tried for c10/34 in rev E specification?
i could actually order some copper wirewound types as seen here ÈÕ¾« ¶¥¼¶ÍĤ ÌìÁú¶¨ÖÆ 100pF 125V OFC 7x15 ö¦ÉùµçÈÝ-ÌÔ±¦Íø
Disclaimer
While the alternate compensation works, is stable and (maybe) sounds better it must be taken in account also that some of Mauro's goals had when he designed RevC are gone:
Going, step by step, from 100pF to 68pf, 47pF and 33pF you can actually ear bass firmness increasing with 47pF the value with better overall balance.
I consider that compensantion only a very instructive experiment and I don't encourage its use unless willing to experiment.
I'm still evaluating it and I've not yet decided if I'll include it as an alternate compensation for my Fremen Edition.
In fact omitting C5, grounding LM3886 to PGND and replacing LM318's PS bass, refinement and soundstage are vastly improved without impact on Mauro's goals. 😉
While the alternate compensation works, is stable and (maybe) sounds better it must be taken in account also that some of Mauro's goals had when he designed RevC are gone:
- higher measured distortion
- Rev C dumping factor linearization after 10Khz is no more effective
- high frequency response is more rolled-off
Going, step by step, from 100pF to 68pf, 47pF and 33pF you can actually ear bass firmness increasing with 47pF the value with better overall balance.
I consider that compensantion only a very instructive experiment and I don't encourage its use unless willing to experiment.
I'm still evaluating it and I've not yet decided if I'll include it as an alternate compensation for my Fremen Edition.
In fact omitting C5, grounding LM3886 to PGND and replacing LM318's PS bass, refinement and soundstage are vastly improved without impact on Mauro's goals. 😉
I just removed C17,18,19,20 and replaced C7 with a 0.1uF X2 cap, with the original C13 that came with the TP kit bypassed, the sound just continues to amaze me. I wonder whether new power supply for LM318 is necessary, but amazing things just never stop popping up.
Didn't told you to remove those bypases? 😀
For C7 I've had best results with film/foil 10nF caps (FKP2 and even better FKS2)
I've listened with the plain PS for three years, it's not 'necessary' but, trust me, the new one it's a big step up 😉
I'm pretty sure that a plain RevC populated with the Ultimate BOM would beat ANY other chipamp (apart My_Evo, obviously... 😉 )
Well, right now I'm putting one channel against the other each trying to beat the other. When your other board becomes available, it will be these against the new one. I think there is potential to be among the best of amps in this wattage category. Just needs some work to get there.
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hehe welcome to the club, soongsc. your journey sounds exactly like the one i took many months ago. wait till you get some blackgates in there, then you'll realize how accurate your statement was 😉
They give good results at C9, C6 and C11. I've left space for BlackGates at C1 and C2 also in V1.4, but haven't got around to trying them there. I have a few BG Fs coming in from Pocoyo in Indonesia to try out at C1 and C2 - we'll see how it goes, but I expect that it will extinguish that last bit of sibilance and edginess that's there in Rev E without the LF01.
This is a great news, so no need for 22mm LS caps... 😉
Wima MKP4 is available both in 7.5mm and 10mm.
When we will tailor the Fremen Edition BOM such value could change for the added capacitance of the stripline
In C9 they're the best cap, in C6/C11 I've tried PKs and preferred Cerafines, in C1 and C2 I'm waiting the new PCB to try them... but Elna RJHs proved to be great caps there.
Siva, did you tried RJHs?
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I don't think the MyRef is edgy, not exactly sure how I can describe it in it's current state, but it just lacks that last bit of emotion that should be in the performances. I have not changed the gm value yet. Hope to get to it later this week.
Even at 0.068uF, these still have large lead distance. I think at least 15mm. But since they are already in there, and I only had two, I never really measured.
I removed the C13 in one channel, sound is cleaner, but not the right punch to rock music. Since it still seems to go low, I can only speculate on the phase. Would be an interesting measurement to do.
I tried RJJs (very similar to RJHs) at C6/C11 in a Rev C long ago, and they were good - and then I found Cerafines, Silmic IIs, BG PKs and Panasonic FMs, all of which were also very good. I need to re-visit the RJJs in Rev E. I also don't have 220uf/50V in either RJH or RJJ at hand. BTW, a good value alternative for C1, C2 is Chemicon KY - similar in many respects to Panasonic FM.
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Are Black Gates back in production or are the available pieces still from scattered surpluses?
Surplus/NOS only, unfortunately. Prices are sky-high on EBay, and will probably keep going higher...
You would think with prices they way they are, that someone would put these back in production. I guess still not enought demand to make it worthwhile. The DIY audio crowd is pretty small potatoes to large industrial corps. Regards
Panasonic FC/FM are a bit edgy, RJHs no and they've a better tonal balance.
If you're seeking for a more alive sound you should consider KOA SPRs in R1/R4.
Also using audio grade resistors (or at least Vishay SMA0207) in the signal path makes a difference.
There are plenty of 0.068uF caps in both 7.5 and 10mm....
I didn't tried RJJs...BTW in C6/C11 I prefer Cerafines.
I C9 they fares well too (RJHs), better balanced than Silmics II.
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there's a great (relatively speaking) deal on 100uf blackgates that i pulled the trigger on a while ago. you could fit c6,11,16 with them which I'm waiting to do.
BLACK GATE F series electrolytic capacitor 100uf25V 8pc | eBay
clave, did you find cerafines to be better choice than silmic ii for c6,11?
BLACK GATE F series electrolytic capacitor 100uf25V 8pc | eBay
clave, did you find cerafines to be better choice than silmic ii for c6,11?