My "audiophile" LM3886 approach

[ClaveFremen]

Originally Posted by AndrewT

R1 is shown connected to PIN8. It is labeled 47k.

I'm sorry Andrew, this time you're completely wrong...

Originally Posted by AndrewT

R4 is the Vdrop for the Zener. Why does a few tens of mA need a heatsink?

It's known that those two resistors in the My_Ref will get very hot, a small heatsink can extend their duration.

[AndrewT]

I don't know where Clave gets his evidence from but I can see R1 labeled as 47k and connected to PIN8.

Just look at the Post1 schematic and you will see exactly that.

[ClaveFremen]

Originally Posted by AndrewT

I don't know where Clave gets his evidence from but I can see R1 labeled as 47k and connected to PIN8.

Just look at the Post1 schematic and you will see exactly that.

Andrew, the schematic at post 1 is outdated.

Every board ever produced use a different numbering.

The image I've attached is from the official My_Ref schematic downloaded from Penasa's site.

You can find attached also TP schematic.

[AndrewT]

Then try to be helpful and link a post with component numbering to the relevant schematic.

do you think ill need heatsinks for to-220 types if i'm to use them in r1 and r4? caddock mp-925 10k ohms

the first thing I did was go and look at the schematic to see why he was asking and what the resistor duty was to require a heatsink.
My response

R4 is the Vdrop for the Zener. Why does a few tens of mA need a heatsink?
R1 is 47k, where is the resistor that needs another heatsink?

showed what I found.

With a supply voltage of 25V and a 12V Zener the current through R4 can max out at ~13mA equivalent to 169mW, quite low for a 1W resistor. Me, I would use two 2k, 600mW, in parallel.

[geoffcooper]

Originally Posted by AndrewT

With a supply voltage of 25V and a 12V Zener the current through R4 can max out at ~13mA equivalent to 169mW, quite low for a 1W resistor. Me, I would use two 2k, 600mW, in parallel.

With 25V trafo secondaries the PSU rails are a little under 35V giving the max on R4 (& R1 on the later schematics) as just under 23mA - lets call that around 500mW which isn't bad for a 1W resister. The idea of two 2k @ 600mW still works of course. And I can confirm that those resisters run quite warm on my boards.

Geoff

[bcmbob]

OT. HEY - Dueling Gurus both being correct on the same page - I like it!!

Hoping this leads to a "Beer Summit" - maybe in Paris.

[PreSapian]

i just got done installing vcap cutf for c7 and... it sounds like nothing, as if i've taken out c7 altogether. coming from mundorf supreme there's a whole new layer of detail, bass is extended further and harmonics are even more vivid. i'm no longer curious enough about myref's capabilities to directly a/b with a capless c7 sound but I imagine this is what dario was getting at. maybe i could've arrived at this stage for a fraction of the cost but as of now, i'm a happy camper

[noSmoking]

hi would someone post the updated schematics board and power supply PLEASE or point me to the post,
I have just started to mod my chips and would appreciate the info!
THANKS

[PreSapian]

after 8 straight hours of listening to music, i just realized that my speaker ports have been plugged up the whole time, doh! (i've been doing this recently after realizing that the chinese plywood i used for the cabinet was still offgasing foul smell from the inside, which had me starting to fabricate a new cabinet last week.)

with the ports clear, the bass just exploded.
so much so that it has caused me to write this re-evaluation.
the bass increase from mundorf supreme is extreme. almost as noticeable as a half of dario's compensation mod. the cap is there alright, but it's only amplifying the dynamic of the music while remaining utterly transparent. the jump from mundorf is as dramatic as it was from going silmic(no bypass) to blackgate. and since mundorf>>fkp2... it's an obvious heirachy.

cutf's been the final piece of the puzzle, the kingmaker, tapping the last bit of magic from myref, and bursting it with bowling alley depth soundstage, vivid harmonics, ultra accurate tonality oh my... i am done. the nirvana is here. 300b, aleph, i need to forget about it all~

so if you gents have a quality .1uf axial caps laying around, please don't hesitate to try them on. i guarantee you i won't have anything to apologize for

[ClaveFremen]

Originally Posted by PreSapian

after doing so, the bass just exploded. i have to re-evaluate my impression of the cap. the bass increase from mundorf supreme is extreme. almost as noticeable as a half of dario's compensation mod. the cap is there alright, but it's only amplifying the dynamic of the music while remaining utterly transparent. sub-bass is truly tangible now. and the bowling alley depth soundstage, vivid harmonics, ultra accurate tonality oh my... i am done. this is nirvana.

I'm happy for you

But you know what I think of phisically big axial caps in C7...

The sound you've obtained is better than without C7?

If so you're hearing a gorgeous coloration...