I have put together the regulated PS by Carlos Filipe, using the LM338's. For some reason I have a 5 volt mismatch betwen
+ & -, but I am also getting an lot of DC on power-up. Any ideas anyone?
+ & -, but I am also getting an lot of DC on power-up. Any ideas anyone?
is dc output on both channels? If so disconnect power rails from the faulty channel and see if power rails are correct. If not disconnect both amps and see what happens. You need to isolate your problem first.
Nuuk said:
Yea, operator error. I have stripped the board and am starting again. Still can't understand why I would get high DC.
Well if you showed some pictures, and the circuit you used, we may be able to offer some help.
Incorrect voltage with that circuit is down to either getting the resistor values wrong, or having a short somewhere. That's why a picture would help us to help you! 😉
Incorrect voltage with that circuit is down to either getting the resistor values wrong, or having a short somewhere. That's why a picture would help us to help you! 😉
Sorry
a bit late for pics!
I asumed I was being justifiably chastised and went back to the drawing board.
Nick, it was the PS on your site that I attempted.
a bit late for pics!I asumed I was being justifiably chastised and went back to the drawing board.
Nick, it was the PS on your site that I attempted.
That's a fairly standard LM3** regulator circuit that Carlos optimised for use in the GC. It is easy to make a mistake with the circuit, I often do!
When you try again, get the voltage outputs correct before connecting to the amp section. 😉
When you try again, get the voltage outputs correct before connecting to the amp section. 😉
Re-made one board. Very slight (0.8v) mis-match between rails, but no DC on turn-on, but a delayed pop/muted thump.
This time I have gone for Nuuk's version of the Filipe PS. I note that CF uses a resistor before the caps, but that is omitted in the Nuuk simpler version. Could this account for the delayed thump?
This time I have gone for Nuuk's version of the Filipe PS. I note that CF uses a resistor before the caps, but that is omitted in the Nuuk simpler version. Could this account for the delayed thump?
Nukk, is carlos's circuit better than the old simple 1000uF cap at the pins like the good old original GC?
Luke said:
It all depends on what you are driving. And to be honest, I prefer the discrete regulated supply of Pedja Rogic best of all.
Puffin said:
0.8v won't matter much Puffin.
I used the LM338 regulated supply with my LM33886 amp and didn't get any thump.
yes I tried that and liked it alot, but it was the tube buffered version with T feedback network, so it was hard to assess the power supply.
Update: I find that the best way to learn is to make mistakes. I was still not out of the water following my previous post. however after a little rearranging I got virtually equal volts on both rails and no DC. After the third rearranging, the penny then dropped as to how the thing really worked.
So, I have now made a pair and installed them. No "boutique" parts, just bog-standard caps and resistors. Initial impressions. Slightly less detail than before, but the jury's out as to whether that is really so, or whether the signal is cleaner. I had previously only been using caps on the chip, and only a bridge rectifier after the tranny. However I think I am getting more music. A more robust presentation. It's early days, but it is certainly no worse than before. No thump/pop on start-up either
So, I have now made a pair and installed them. No "boutique" parts, just bog-standard caps and resistors. Initial impressions. Slightly less detail than before, but the jury's out as to whether that is really so, or whether the signal is cleaner. I had previously only been using caps on the chip, and only a bridge rectifier after the tranny. However I think I am getting more music. A more robust presentation. It's early days, but it is certainly no worse than before. No thump/pop on start-up either
Puffin, have you had the chance to evaluate it a bit more?
Whats the verdict?
Nuuk, Have you tried this on a Bridged Chipamp? I had in mind 2XLM3886
😎
/JZ
Whats the verdict?
Nuuk, Have you tried this on a Bridged Chipamp? I had in mind 2XLM3886
😎
/JZ
Will evaluate it over the next few days. I built a bridged LM3886. Very good, but I don't need that much power. I just did it to see if I could (point to point, no PCB)
Nice, And you used that LM338 regulated Supply with it?
I made a "new" layout of the SuperSymmetry "Susy" Chipamp based on Schematics from Russ at this forum.
And i,m think of using a regulated supply for it.
/JZ
- Status
- Not open for further replies.