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-   -   LM338 regulated snubberized PSU for audio amplifiers (http://www.diyaudio.com/forums/chip-amps/56106-lm338-regulated-snubberized-psu-audio-amplifiers.html)

carlosfm 25th April 2005 11:46 PM

LM338 regulated snubberized PSU for audio amplifiers
 
2 Attachment(s)
Here it is.
Results are impressive, this elevates the chipamp to a league of it's own.:cool:

:att'n: Notice that I recommend 1,000~2,200uf caps on the chips, snubberized.:att'n:
I'm using 2,200uf.

This regulated PSU is good for two chips (LM3886, etc.).

As a side note, this is not only a PSU for chip amps.
There are discrete class-A amps around that use the LM338 regs.
These amps will also benefit from the snubber.
No, let me put it this way: every regulated PSU benefits from a snubber. ;)

The values for the snubber were calculated for the LM338's output impedance. Don't ask me how, I won't reveal it.

Enjoy.:cool:

homer09 26th April 2005 12:10 AM

I knew you wouldnt resist sharing your most recent recipe :D

how does this supply compare to non-regulated high-cap snubbed PSU?

Is this the new chip amp PSU king :eek: ?

cjd 26th April 2005 12:10 AM

Now, if I could run four chips off this... ;) X-GC using a pair of LM4780's per side, you know? (the chips showed up today in the mail finally!)

Wonder what the flavor of the month will be next month. Discrete? ;)

C

carlosfm 26th April 2005 12:24 AM

Quote:

Originally posted by homer09
I knew you wouldnt resist sharing your most recent recipe :D
how does this supply compare to non-regulated high-cap snubbed PSU?
Is this the new chip amp PSU king :eek: ?

This is it.;)
I couldn't help but sharing...:clown:

Quote:

Originally posted by cjd
Now, if I could run four chips off this... ;) X-GC using a pair of LM4780's per side, you know? (the chips showed up today in the mail finally!)
Wonder what the flavor of the month will be next month. Discrete? ;)
C

I was thinking in paralleling, but results are so impressive with this PSU and single chips that I'm not doing it.
Deam it, this stereo power amp sounds better with my speakers than a Krell integrated (used as a power amp) I had at home last week.:eek:
What's on my plans for soon is to make two small monoblocks with two chips each for bi-amping my Epos ES11 speakers.

XELB 26th April 2005 12:50 AM

I will tell a friend to try it on a stereo bridged LM4780 amp.
(my PSU is not regulated)

I hope to have news tomorrow.
Since you don't tell the miraculous formula, I will tell him to buy thousands of caps and resistors to find out the best combination :D LOL :dead:

carlosfm 26th April 2005 12:59 AM

Quote:

Originally posted by XELB
I will tell a friend to try it on a stereo bridged LM4780 amp.
(my PSU is not regulated)

I hope to have news tomorrow.
Since you don't tell the miraculous formula, I will tell him to buy thousands of caps and resistors to find out the best combination :D LOL :dead:

:confused: :drunk:

You have a complete PSU schematic with the right values.
What do you want more?:confused:

:crazy:

homer09 26th April 2005 01:09 AM

Quote:

Originally posted by carlosfm


:confused: :drunk:

You have a complete PSU schematic with the right values.
What do you want more?:confused:

:crazy:


i think he wants to check your math :snooty:

XELB 26th April 2005 01:14 AM

You got me... :dead: I was with hope that you would tell! :p LOL :D

[inocent] :goodbad: [/inocent]




If you say that this one is much better, I will give it a try but I only have 8,600uF caps.


What electronic House you recommend in Lisboa ?
I will have to buy some parts.

mateo88 26th April 2005 01:16 AM

Re: LM338 regulated snubberized PSU for audio amplifiers
 
Quote:

Originally posted by carlosfm
The values for the snubber were calculated for the LM338's output impedance. Don't ask me how, I won't reveal it.

[/B]

If you pretend the power supply is a speaker and calculate a zobel for it, that gets you in the general ballpark. Mess around with the values a little to see what works best.

carlosfm 26th April 2005 01:26 AM

Quote:

Originally posted by XELB
If you say that this one is much better, I will give it a try but I only have 8,600uF caps.
That's not important, those are fine.
On this PSU you should have around 10V more voltage before the regs, so there's plenty of voltage to sag.
After the regs, the voltage is steady as a rock, of course.;)
Big capacitance is not needed, 4,700uf is fine, or up to 10,000uf.


Quote:

Originally posted by XELB
What electronic House you recommend in Lisboa ?
I will have to buy some parts.

In Lisboa you have Dimofel and some others, but not too good for decent parts. Sometimes you find them, but you have to search.
There's a guy in Cacem that has Philips caps is almost all values, and 1% film resistors.
It's on the main street, on the Bons Amigos (I think it's called this way) shopping center.


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