Hi Carlos,
When I tried the LM338 for the first time the set-up was:
- two 4700uF caps per rail;
- LM338s physically mounted to the second of these caps;
- LM338s adj pins were bypassed by WIMA MKS 1uF caps;
- other than local caps mounted to the LM3875s, no additional caps after the regulators were used;
- regulators were relatively close to the power IC’s;
- for the start I have used usual 1000uF at the LM3875’s pins.
I liked it instantaneously, without any
-in. I can not remember if -in brought any improvement or not, so if it id, it was not huge.
Usage of lower value, higher quality (BG) local LM3875 caps was quite meaningful.
Nick, that part with philosophy actually happened years ago.
Pedja
When I tried the LM338 for the first time the set-up was:
- two 4700uF caps per rail;
- LM338s physically mounted to the second of these caps;
- LM338s adj pins were bypassed by WIMA MKS 1uF caps;
- other than local caps mounted to the LM3875s, no additional caps after the regulators were used;
- regulators were relatively close to the power IC’s;
- for the start I have used usual 1000uF at the LM3875’s pins.
I liked it instantaneously, without any
-in. I can not remember if -in brought any improvement or not, so if it id, it was not huge.Usage of lower value, higher quality (BG) local LM3875 caps was quite meaningful.
Nick, that part with philosophy actually happened years ago.
Pedja
Done
Guys, let me tell you, this is special.
It's getting late, I can't turn up the volume as I wish to, but what I hear now is that magic returned.
More auditions tomorrow when I arrive from work.
Here's what I did:
- removed the 100uf cap at the reg's output and put small 47nf polyesters.
- Removed the 1000uf caps at the chip's PCBs and put 100uf.
S' beautiful.
I'm gonna let it-in 'till tomorrow.
Doesn't matter if it does a difference or not, at least the new electrolythics need it.
I'm now
-in' a pure malt to Nuuk and Pedja.
Gotta go listen to Keith Jarrett on vinyl.
BTW Pedja, I have the Adj. resistor bypassed with 47uf caps.
And protection diodes.
Guys, let me tell you, this is special.
It's getting late, I can't turn up the volume as I wish to, but what I hear now is that magic returned.
More auditions tomorrow when I arrive from work.
Here's what I did:
- removed the 100uf cap at the reg's output and put small 47nf polyesters.
- Removed the 1000uf caps at the chip's PCBs and put 100uf.
S' beautiful.
I'm gonna let it
-in 'till tomorrow.Doesn't matter if it does a difference or not, at least the new electrolythics need it.
I'm now
-in' a pure malt to Nuuk and Pedja. Gotta go listen to Keith Jarrett on vinyl.
BTW Pedja, I have the Adj. resistor bypassed with 47uf caps.
And protection diodes.
Re: Done
The norm for these regulators is probably the same as for LM3X7s: small cap at the output (up to 150uF at most) and big cap on adj. resistor. Protection diodes are a must if bypassing with electrolytics.
Also small caps close to gainclone, I'd say 47uF Pana FC. Rowland's seems to use SMD 'lytic, which value I can't say, but it's small. Perhaps 4.7uF or so.
Carlos (the other)
carlosfm said:
BTW Pedja, I have the Adj. resistor bypassed with 47uf caps.
And protection diodes.
The norm for these regulators is probably the same as for LM3X7s: small cap at the output (up to 150uF at most) and big cap on adj. resistor. Protection diodes are a must if bypassing with electrolytics.
Also small caps close to gainclone, I'd say 47uF Pana FC. Rowland's seems to use SMD 'lytic, which value I can't say, but it's small. Perhaps 4.7uF or so.
Carlos (the other)
Carlos, Very interesting results. Since I have limited time right now to prototype, I have to live vicariously thru every one else's success. I am now lifting a fine higher octane adult malt from Scotland on your progress.
Not that it matters, but what type of speakers are you doing your evaluation on?
BobK
Not that it matters, but what type of speakers are you doing your evaluation on?
BobK
Re: Re: Done
Carlos, I had some 47uf caps looking at me, but I decided to take on Nuuk's suggestion for 100uf first.
Anyway, this report is not final, I'm gonna listen to this thing, fine-tune if I must and listen again.
As I always do.
Let's see the final result.
I expect to finish the whole thing (with box) this week, I hope soon to have some pics to show.
Forgot to say: both amps are with LM3886 chips.
carlmart said:
Carlos, I had some 47uf caps looking at me, but I decided to take on Nuuk's suggestion for 100uf first.
Anyway, this report is not final, I'm gonna listen to this thing, fine-tune if I must and listen again.
As I always do.
Let's see the final result.
I expect to finish the whole thing (with box) this week, I hope soon to have some pics to show.
Forgot to say: both amps are with LM3886 chips.
Left this thing playin' since last night.
Arrived home, put "Focal/JMLab - Le grand spectacle du son", turned the colume up up up and...
INCREDIBLE!!!!
Bass is amazing!
I'm surrounded by detail!
It's a festival.
Now excuse me, gotta go change those cheap 100uf caps I put last night for something better.
Wait... I have to gain some courage to power this thing off...
Arrived home, put "Focal/JMLab - Le grand spectacle du son", turned the colume up up up and...
INCREDIBLE!!!!
Bass is amazing!
I'm surrounded by detail!
It's a festival.
Now excuse me, gotta go change those cheap 100uf caps I put last night for something better.
Wait... I have to gain some courage to power this thing off...
Dismantled the bunch of aligators again and...
...Changed the cheap
100uf caps for Philips 33uf/40v.
Changed the 100uf before the OPA627 regulators, on the GC board, with 10uf (they have resistors before them).
Bypassed the 2,200uf caps before the LM338s with 470nf polys.
Connected the whole bunch of aligators.
Power on...
Does it get any better than this?
Guys, I think I'll stop here, or else I'll put a 1pf cap and that's it.
No, seriously, this thing IS special.
Nuuk, are you there?
Try it.
Just a conclusion:
- Very small cap after the LM338 (I used 47nf poly), or no cap at all, if you use them very near the chips.
- From 4,700uf to 10,000uf total capacitance before the regs (I use 4,700uf on the MUR860's board and 2,200uf on the regulators' board).
- Small cap on the chip (I'd say between 22uf and 100uf).
Gotta go listen, something made "click" and I can't stop listening!
...Changed the cheap
100uf caps for Philips 33uf/40v.Changed the 100uf before the OPA627 regulators, on the GC board, with 10uf (they have resistors before them).
Bypassed the 2,200uf caps before the LM338s with 470nf polys.
Connected the whole bunch of aligators.
Power on...
Does it get any better than this?
Guys, I think I'll stop here, or else I'll put a 1pf cap and that's it.
No, seriously, this thing IS special.
Nuuk, are you there?
Try it.
Just a conclusion:
- Very small cap after the LM338 (I used 47nf poly), or no cap at all, if you use them very near the chips.
- From 4,700uf to 10,000uf total capacitance before the regs (I use 4,700uf on the MUR860's board and 2,200uf on the regulators' board).
- Small cap on the chip (I'd say between 22uf
and 100uf).Gotta go listen, something made "click" and I can't stop listening!
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