New PCB for shoebox size NAC preamp part II
- Thread starter timH
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Hi Tim,
I was going to direct you to the build manual for what capacitors to fit where, but you have rightly diagnosed that the part-BOM for turning the simple-asymetric version into the local-regulated symmetric version is missing the 47uF smoothing caps after the 27R regulator output resistor for the negative regs. Oops! Sorry about that! You are correct, 47uF decoupling caps should be fitted after the 27R resistor on all the local regs.
I think a revisit to the build manual is in order
Cheers,
Jim.
I was going to direct you to the build manual for what capacitors to fit where, but you have rightly diagnosed that the part-BOM for turning the simple-asymetric version into the local-regulated symmetric version is missing the 47uF smoothing caps after the 27R regulator output resistor for the negative regs. Oops! Sorry about that! You are correct, 47uF decoupling caps should be fitted after the 27R resistor on all the local regs.
I think a revisit to the build manual is in order
Cheers,
Jim.
Noooooooooooooooooooooo!
Don't do it! I just sold all my hifi, including my prized 260z, to fund relocation to the USA... that is to say, I sold all my hifi with the exception of the starfish... I couldn't be parted from it. I'd doubt you'd get a fair price for it (a fair price being cost to performance ratio based upon Naim offerings!) and you'd regret it in the long-run.
You've made a beautiful amp, it'd be a shame to let it go. How about this: listen to nothing but the starfish for a couple of weeks, then plug in your old preamp and decide if it's worth selling the 'fish for a few hundred pounds...
Carl
Finally fitted all the wound cores and traco and lm337's and all I can say is wow! More detail, more drive, clearer rhythms and just more more music. Even girlfriend says more clarity. Thanks Jim - now whats this earth regen thingy?
Oh and here's some photos - I've left some space for some more RTX's and maybe vbe's. It's not a shoebox any more - maybe an FMB box?
Tim
Oh and here's some photos - I've left some space for some more RTX's and maybe vbe's. It's not a shoebox any more - maybe an FMB box?
Tim
Jo,
There's some notes earlier on in this thread about the earth regen circuit.
I havent dropped this into the build notes yet as I dont consider this bit to be fully sorted and tested yet.
(Despite the fact it's sat in my preamp for a few months and worked faultlessly )
(It was just something I banged together to try out an idea...and it seems to have worked rather well)
I'll see if I can find what page the notes are on.
Jim.
There's some notes earlier on in this thread about the earth regen circuit.
I havent dropped this into the build notes yet as I dont consider this bit to be fully sorted and tested yet.
(Despite the fact it's sat in my preamp for a few months and worked faultlessly
)(It was just something I banged together to try out an idea...and it seems to have worked rather well)
I'll see if I can find what page the notes are on.
Jim.
Jim - yes the big caps make a difference - they keep the detail of the SMR's but are less prone to brittleness - they make such a difference that I made the case wider to make room for two more
Carl - the knobs are from thl audio - something 3818 - I bought them with the big caps
The cases I make myself in a C and U design using 3mm ali for top and sides which makes the C, 3mm ali base and 1mm front and back making the U. Ali pre-cut by an ebay seller. Join it together with ali angle section - some glued some screwed.
I'll do some drawings if you want.
Most tricky thing is getting the paint to stick - just don't handle it too much afterwards.
Not as good as the naim stuff obviously but in a rack or on shelves they're not too bad plus you can make them any size you want
Carl - the knobs are from thl audio - something 3818 - I bought them with the big caps
The cases I make myself in a C and U design using 3mm ali for top and sides which makes the C, 3mm ali base and 1mm front and back making the U. Ali pre-cut by an ebay seller. Join it together with ali angle section - some glued some screwed.
I'll do some drawings if you want.
Most tricky thing is getting the paint to stick - just don't handle it too much afterwards.
Not as good as the naim stuff obviously but in a rack or on shelves they're not too bad plus you can make them any size you want
Yep the ground regen thingy works and is another step forward (more solidity of instruments, more drive, more rhythm again). I found the best value resistor combination was R1 of 120r and R2 of 1320R (made up from 1k2 and 120r) Gave me +15.4v and -14.6v. - close enough I thought
Now waiting for two more MultiCap RTX's for the line stage input caps.
I've also been thinking about fitting VBE's (I've got the extra TRACO already). Although I'm considering putting them after the 1086's (a la TeddyReg thread) If I do this can I get rid of the 27r 47u filter?. If so it would be a great help bacause the input and output of the VBE could go where the 27r is and the ground could use the 47u track
Tim
Now waiting for two more MultiCap RTX's for the line stage input caps.
I've also been thinking about fitting VBE's (I've got the extra TRACO already). Although I'm considering putting them after the 1086's (a la TeddyReg thread) If I do this can I get rid of the 27r 47u filter?. If so it would be a great help bacause the input and output of the VBE could go where the 27r is and the ground could use the 47u track
Tim
Jo Sharp
Pulls on doors marked push
I'm starting work on mine today, if the last batch of bits from Farnell arrives. Going straight into the symmetrical local reg version with 2 tracos. Will be fitting in a 62 case with the 62's volume control.
Plan to experiment with the Gnd regen and VBEs at a later stage...also will compare using SRegs.
Any last minute hints or tips before I kick off?
Plan to experiment with the Gnd regen and VBEs at a later stage...also will compare using SRegs.
Any last minute hints or tips before I kick off?
Wilky
pfm Member
Hi Jo.
If you happen to reverse any of the electrolytics, then adult-sized Pampers might not go amiss!
Other than that, I think you are in for a pleasant surprise.
Let us know how you get on.
Dave.
LOL!
I'd just suggest taking your time.
There are a surprising number of components in it, dont try and get it built all in one session.
Luck,
Jim.
Jo,
If I was doing this again, I'd avoid as much desoldering as possible because the starfish pads are small and delicate. To this end, plan, plan and plan again. Wind your inductors and install them only once; install the 0V regen circuit early instead of retrofitting it. Some may say otherwise, but you're going to do it anyway!
The one thing you'll miss doing it this way will be to hear the difference the various circuit permutations can have; but then again, you'll be able to hear how it sounds compared to the rest of your kit, so why worry
Have fun and post some pr0n for us bodgers to ogle!
Carl
If I was doing this again, I'd avoid as much desoldering as possible because the starfish pads are small and delicate. To this end, plan, plan and plan again. Wind your inductors and install them only once; install the 0V regen circuit early instead of retrofitting it. Some may say otherwise, but you're going to do it anyway!
The one thing you'll miss doing it this way will be to hear the difference the various circuit permutations can have; but then again, you'll be able to hear how it sounds compared to the rest of your kit, so why worry
Have fun and post some pr0n for us bodgers to ogle!
Carl
Jo Sharp
Pulls on doors marked push
Jo,
If I was doing this again, I'd avoid as much desoldering as possible because the starfish pads are small and delicate. To this end, plan, plan and plan again. Wind your inductors and install them only once; install the 0V regen circuit early instead of retrofitting it. Some may say otherwise, but you're going to do it anyway!
The one thing you'll miss doing it this way will be to hear the difference the various circuit permutations can have; but then again, you'll be able to hear how it sounds compared to the rest of your kit, so why worry
Have fun and post some pr0n for us bodgers to ogle!
Carl
Carl,
that's why I'm going straight for the local reg symmetrical model. Don't want to be removing power reg circuitry.....
What do you mean by "wind inductors and install only once"?
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