My design L20D IRS2092+IRFI4020H 200W8R

[noah katz]

Your amp will not be able to use the full 78V, because the available current from power supply will be limited first.

PS storage caps will allow brief bursts at full voltage; add more for less briefness

 

[DarpMalone]

PS storage caps will allow brief bursts at full voltage; add more for less briefness

I've got 65,600uF total (32,800uF for each L25D). Hopefully that's sufficient.

 

[luka]

I've got 65,600uF total (32,800uF for each L25D). Hopefully that's sufficient.

about 10 times too much with smps, and still too much even if you use 50-60hz transformer... but it never hurts to have it like that

 

[DarpMalone]

I'm using a linear PS... I know that too much capacitanceis a no-no in SMPS, but in a linear supply would this amount have a negative effect or is it just a matter of diminished returns beyond a certain pt.?

 

[MrSlim]

I'm using a linear PS... I know that too much capacitanceis a no-no in SMPS, but in a linear supply would this amount have a negative effect or is it just a matter of diminished returns beyond a certain pt.?

The inrush current of too much capacitance can damage the rectifier diodes, but I doubt that will be a problem in your case.

Back in the old days I built a capacitor bank for an old Dynaco Stereo 150 amp that was as big as the amp itself using old Caps from computer mainframe power supplies. I had to build a soft start circuit to avoid the inrush damage.

I went looking for an inrush calculator to look smart, but the formula I found needed an inductive component, and I didn't feel like digging any further

 

[DarpMalone]

Gotcha... I read that somewhere in this forum... I've also purchased a soft start module from Connex electronic, so I'll be alright.

Thanks!

 

[ionutzxpo]

Hi,cand someone mesure the
AC (residual) on output ,without input signal!
I have 70mV (is that OK?) on my amps L25D switching @300Khz

 

[ljm_ljm]

Hi,cand someone mesure the
AC (residual) on output ,without input signal!
I have 70mV (is that OK?) on my amps L25D switching @300Khz

The L25D you can set the operating frequency.

I usually designed to 420K HZ, .. on the PCB resistor nominal 470OHM.

470 the R = 650K
390 the R = 550K
300R = 420K
The higher frequency allows the residual PWM sine wave output to reduce the voltage value.
But may produce distortion THD switch, and more heat.

It can be set arbitrarily. I recommend the 300R, the PWM = 420K. Reference IRAUDMP7

 

[vakkuj]

Hi,

Finally i have got these from Taobao store through my friend, assembled all the parts.
Attached is the photo of the items i have purchased.

Could someone please give me wiring instructions to do with the attached boards. My Speaker is a 6 Ohm speaker. Should i make any changes ?

And what should be the transformer ratings, how many core ?

1. For Amp. Is it 22 - 0 - 22 Volt , How much should be current rating ?

2. Delay board + Protection board - Voltage ?

3. Mini Preamp What should be voltage ?

Thank you...


[URL=http://imageshack.us/photo/my-images/860/l15dg.jpg/]

An externally hosted image should be here but it was not working when we last tested it.

Uploaded with ImageShack.us[/URL]

 

[deChrLam]

@vakkuj your questions show you have no idea what you are doing and or are too lazy to read the information off the circuit boards and find the wiring information in this thread or on the many ebay pages and others that sell these boards.

I am not going to help you electrocute yourself or start a fire.
You need to do your homework.

 

[vakkuj]

I have not seen any wiring information with LJM's new board power supply + speaker protection board.
Will be glad if any one could point me to the specific post.
Thank you

 

[clm811]

Received my L25D Boards, and everything looks good, except:

There was no thermal compound on the H669A BJC or IRFB4020's, so I applied some.

While operating at approximately 10wattsrms, the H669A BJC and three green resistors got very hot(could not keep finger on it for any time).

For this thing to be capable of 300W I believe a larger heat sink will be needed.

Opinions, or similar experience to share?

-Chas

 

[nigelwright7557]

Its surprising how small a heatsink you can get away with for class d.
I test my 750 watt amps on full power for a few seconds with no heatsink and the transistors dont get hot.

Components can run very hot yet still be well inside their SOA.
Power resistors do tend to run hot anyway.

 

[ionutzxpo]

hi,on my L25D the two rezistors from 5V6 diodes are at 40 degrees and the on at the NPN tranzistor has allmost 60 degrees yet the amp works non stop over 1 month

 

[solviken]

So i just finished my l25D amp. with a 650watt 2x50vac and 60 000uF psu thats feeding the boards with 70vdc.

When i crank up the sound to very high volums one of the bords just shuts of and the otherone continiue. Then i have to turn the volum a little down and it comes back!

Any ideas why?

 

[ionutzxpo]

the amp reaches hard clipping and protection mode is activated!

 

[solviken]

the amp reaches hard clipping and protection mode is activated!

So then it has reached its max output? Do you think it will perform better with active cooling?

But how is it possible to Get clipping from a 250w amplifier.. When its impossible to get the Rotel RB1070 with its puny 125w to go into protection mode!

 

[ionutzxpo]

read the application note for irs2092

 

[solviken]

Will do

 

[solviken]

I thought that i should share my Almost finished L25D project Still havent added the Speaker protection board, cause i dont have anything to power it with ATM.

Here are som pictures!