My design L20D IRS2092+IRFI4020H 200W8R

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doctordata

doctordata

Member
Joined 2010
camelator said:
Sorry,
but I didn't understand.
Are you talking about the fact it is a prototype?
Or bad links?
Or PCB quality?
Or components?
Click to expand...

Class D Amps and SMPS generate a lot of HF noise .
Your wiring needs to be tidy , twisted and in a grounded metal chassis .
For input wiring use twisted or shielded cable and keep this as far as possible from the output and power wiring .
For testing this prototype for hum , short the inputs with a wire bridge . The amps should be (almost) quiet then.

Cheers ,

Rens
 
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DannyElfman

Member
Joined 2011
Guys,
A quick one for you. I've already built an amp (UCD modules) for my front and center speakers.
I have left a linear power supply (300Va) ready to use, VC would be 42V.

Do you think I can power an L7 or L20 module with it ? (I see most of the time 60 ou 70V here and there).

This would be only to power my surround speakers. I am not looking for any huge power or even hifi audio quality, just a cheap way to bring sound to my surround speakers and use my leftovers :D
 
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redjr

Member
Joined 2011
blairfrischx said:
Some good news and some bad news here.

Good news first - it functions at 35V +/-

o1kvfh.jpg


See that little blue light? Beautiful. :)

All that was necessary was swapping out the resistors as noted in the quoted post.

7UIfQh.jpg


Now, on to the bad news. After removing, modifying, and rewiring the amp board in the one amplifier, I turned power on and POOF. Smoke. :yell: I accidentally wired DC+ to the wrong terminal on the board, and it fried something on both boards. The power supply rectifier/filter board was easy enough to fix - remove burnt traces and replace with thin wires. The amp board is another story entirely. I fear I may have burned up the opamp, rendering it useless. :xmasman: There are no obviously burned traces on the PCB or components, and yet it does not function, and the pretty blue light does not function.

Anyway, that's a problem that is simple enough to solve by buying a new amp board, replacing the resistors, and not wiring incorrectly. This post is more to announce to everyone that it is possible to swap resistors and operate at lower voltage.

Now here's an album of the project so far: Photo Album - Imgur
Click to expand...

Funny what incorrect polarity does. :) Hope all is well now a year later.

Rick
 
doctordata

doctordata

Member
Joined 2010
DannyElfman said:
Guys,
A quick one for you. I've already built an amp (UCD modules) for my front and center speakers.
I have left a linear power supply (300Va) ready to use, VC would be 42V.

Do you think I can power an L7 or L20 module with it ? (I see most of the time 60 ou 70V here and there).

This would be only to power my surround speakers. I am not looking for any huge power or even hifi audio quality, just a cheap way to bring sound to my surround speakers and use my leftovers :D
Click to expand...

a L15D will probably work fine on +/- 42 Volt . give it a go and if the undervolt protection kicks in you only have to change a couple of resistors , all well described in this thread and the reference design . it will be hifi audio quality and around 85W in 8 ohms .

Cheers ,

Rens
 
doctordata

doctordata

Member
Joined 2010
DannyElfman said:
I guess you are definitely right. The L15 should do the trick according to LJM :
Click to expand...

I had one spare L15D board on my bench , so I tested it today and it worked great on my bench supply at +/- 40 Volt . ( even on +/- 30 Volts )
I remember reading somewhere that LJM left the under- and over protection out of his design , so you'll be fine with the L15D's.
As a bonus , they have lower distortion and are cheaper !

Cheers ,

Rens
 
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Webechillin

Member
Joined 2012
LJM L25D inductors running HOT 150 deg. F -- Normal??

Hello
I put together some LJM L25D amps from Zoe on ebay with no problem, PCB quality is very good. But doing a burn in test I found the inductors were very hot, after 15 minuites, measured with my Fluke at 150 deg. F. Is this normal? I tried with headphones and 6 ohm speakers, same result. Im concerned with the inductor temperature The inductor is physically touching 2 capicators also heating them up, really can't be good can it? I have it running on a linear power supply at +/- 67 VDC
Any opinions?

Thanks
webechillin
 
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Deleted member 148505

Webechillin said:
Hello
I put together some LJM L25D amps from Zoe on ebay with no problem, PCB quality is very good. But doing a burn in test I found the inductors were very hot, after 15 minuites, measured with my Fluke at 150 deg. F. Is this normal? I tried with headphones and 6 ohm speakers, same result. Im concerned with the inductor temperature The inductor is physically touching 2 capicators also heating them up, really can't be good can it? I have it running on a linear power supply at +/- 67 VDC
Any opinions?

Thanks
webechillin
Click to expand...

Based on my experience, inductors (depending on core type) have different temperature rise with switching frequency used and inductance value.

Try to increase the switching frequency to 350kHz and check if it helps. (there's a tradeoff, IRS2092 will become hotter)
 
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Webechillin

Member
Joined 2012
ljester87

Try to increase the switching frequency to 350kHz and check if it helps. (there's a tradeoff, IRS2092 will become hotter)
Click to expand...
The switching frequency is about 384 KHZ measured with a scope, and permanently set by a fixed value resistor, The resistor was one of only 2 components pre soldered to the board, I had to install all the other parts.
Looks like LJM did not want to take any chances on that.

Webechillin
 
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redjr

Member
Joined 2011
joemac2013 said:
Just finished amp with L25D 's, stereo.... I use toroid 52vac per side to rectifier PCB with 68
of those 150 mfd 80v electrolytic caps... The transformer is 550va size.... Also I use a 30 amp speaker protection PCB... Using little NE5532a preamp module with Bass, Mid, Treble, Volume controls... Anyway my layout was nice and when I turned power on I was and am
Very Pleasantly surprised! It works so nice! I am very pleased. I did have to purchase some speakers that can handle the power, and they turned out to be very nice too! Anyway bottom line is the LJM L25D power amp module sounds like a million bucks! Start building your new power amp today! I'm going to start working on a preamp that get rid of the NE5532's in favor of discrete, however I want Gain, Bass, Treble, also a vacuum tube buffer along with hi filter and loudness switch! So much for purest! It is going to sound nice! This I know! -Joe
Click to expand...
Joe, Just going back over some old threads and found this... Do you have any pictures of your project you can share? Sounds cool. Those L25D modules really are shining little diamonds. I'm impressed more and more as I listen to them. - Rick
 
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digisound08

Member
Joined 2008
single voltage smsp - can I use it ;)

Small problem, having seen that I ordered L15D and SMPS500RS 48V with single voltage ... any idea if I could run the L15D with this smps (the manul says single voltage :(
didn`t realize that there are differnet models of the smps500. Now they took a flight to me and I would be glad if I could use them for the L15D.
any idea where to connect GND + and - ?
thanks!
 
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Deleted member 148505

Webechillin said:
ljester87

The switching frequency is about 384 KHZ measured with a scope, and permanently set by a fixed value resistor, The resistor was one of only 2 components pre soldered to the board, I had to install all the other parts.
Looks like LJM did not want to take any chances on that.

Webechillin
Click to expand...

Yah too bad, the osc freq is not adjustable. My L25D's stock inductor runs hot too.
 
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