My design L20D IRS2092+IRFI4020H 200W8R

Hi ljm,
what you write is pure nonsense.

Your amp modules are not at all the same as the reverence design.
Any valuable product has an exact schematic for service purpose. Yours not.

Your amps often fail without logical cause, mostly because of fake parts I suppose. Repairing them is a pain in the a**, because of missing schematic.

Buying a new amp module is no solution, because it may have just the same used/ underspec/ fake/ garbage parts as the one that failed.

Your l15D , l15D sms, l15D pro and l15D power have all different parts. You know that.
So no reverence design at all.

Sorry ljm, this is no customer service or quality design without an exact schematic for a DIYS part. If you are not able to do one, this is very poor.


While I agree with much of what you say, it is not uncommon to withhold circuit diagrams (schematics to our US cousins). As a bassist, I have tried for years to get a Markbass circuit diagram and have failed. A markbass amp costs many may times more than LJM's designs.
 
It is something different, if you develop your own complicated design, with a lot of work and knowledge. Here has someone modified a reverence design with some add on´s and some "save it´s" and is selling a module for DIYS. So providing a schematic is not giving away intellectual property, but just annoying for the buyer who has to integrate this part in his design.
I have seen some other “developments” from this source, most are copy´s of older commercial products.
 
Hi ljm,
what you write is pure nonsense.

Your amp modules are not at all the same as the reverence design.
Any valuable product has an exact schematic for service purpose. Yours not.

Your amps often fail without logical cause, mostly because of fake parts I suppose. Repairing them is a pain in the a**, because of missing schematic.

Buying a new amp module is no solution, because it may have just the same used/ underspec/ fake/ garbage parts as the one that failed.

Your l15D , l15D sms, l15D pro and l15D power have all different parts. You know that.
So no reverence design at all.

Sorry ljm, this is no customer service or quality design without an exact schematic for a DIYS part. If you are not able to do one, this is very poor.

In fact, these circuits are very simple. And IR company has ready-made circuits.
I don't want to keep it secret. It's just that I don't think anyone who can understand the circuit diagram can understand the l15d circuit. It's the same as IR.
If you can't understand l15d circuit. Just tell him. He still can't understand.
For those who don't understand, discuss with him for a year. He still doesn't understand.
This is meaningless.
If you don't think it's acceptable without circuits. Then you don't have to buy them.;)
 
Envy is a widespread evil.
the result is often arrogance;
which is not far from... well, that weakness which (apparently still increasingly) determines how we deal with each other.
regrettably...


please, sir LJM, allow me to thank you for what you have made possible for people,who like hifi & perhaps can not afford sacredholy "commercial" products. hopefully you will continue to do so - in the sovereign way you used to!

by the way: i indeed own, know and enjoy (music!) most of your creations (as far as those are available in europe).



glad you are here!:up:
 
Hello,
I need to reduce input signal coming in from a cambridge soundworks t500 mother board which I have jerryrigged to power this amp. When I play my sub loud, it cuts out. I'm thinking it might be speaker protection on this amp. Would the best solution be to replace the 100k resistor that is right next to the input connector to something of a higher value?? I'm very novice at this kind of stuff, any help would be very appreciated!
 
totally out of simple just for business , all i can say is this amp is design for business not for performance, i have original iraudump7 bought it from digikey, using it from 2010 and until now its working all the time. the original has full protection, ovp, uvp, thermal, ocp, this design performance will never failed or blown your mosfet, but for business they wont include it because its BUSINESS :D.
 
i have 4 pieces of L15d running in my car, using step up switching power supply which is not recommended by LJM

initially i run all 4 on 1 supply, the board don't like it at all, it heat up without signal and giving weird noise.

i purchase another power supply, so now each power supply serving 2 boards, been singing quite happily for a year now, despite the 2 i burn during initial stage because of the power supply issue, all been good.

and its all in the trunk, don't think it would be in any harsher environment then that
 
I've been using my 2 channel L25D amp for a few months now. They are running on +/- 65v.
So far I am very happy with them. They do tend to run somewhat hot to the touch so I have fitted an old cpu heatsink to the existing heatsinks that come with the kit.

I am currently testing my USB DAC Kit CS8416 + CS4398, and I'm having some volume problems.

First of all the windows volume does not work anymore, but I understand that is just what happens when you connect a dac through usb.

The biggest problem is that the speakers are TOO LOUD.
I am now using a 50k volume pot and no preamp. I have to turn the volume pot all the way down and turn the volume slider in Foobar all the way down too

Now I realize that lots of power was something I wanted when I started my first amplifier project, it seems now that acurate and usable volume control is more of a priority of me.

What is the best way to fix this problem? use a larger value potentiometer? Or change the gain settings on the amp or the DAC?
 
...First of all the windows volume does not work anymore, but I understand that is just what happens when you connect a dac through usb. The biggest problem is that the speakers are TOO LOUD.
I am now using a 50k volume pot and no preamp. I have to turn the volume pot all the way down and turn the volume slider in Foobar all the way down too...

My current setup drives power amps directly from an Asus USB sound card attached to an old Windows 10 desktop computer - no preamp. I can adjust volume using the Windows 10 volume adjust or the Asus Sonic Studio application. It works perfectly. Is it possible you have a driver issue with your sound card? (I'm not familiar with it.) When you open up the Windows Volume Mixer do you see your device? I've used multiple USB sound cards and Windows could always control the level. I'm also pretty surprised that you can be at the bottom of a 50k pot with too much level output. Does the pot control the volume at all? (I assume you have the pot connected correctly?)
 
My current setup drives power amps directly from an Asus USB sound card attached to an old Windows 10 desktop computer - no preamp. I can adjust volume using the Windows 10 volume adjust or the Asus Sonic Studio application. It works perfectly. Is it possible you have a driver issue with your sound card? (I'm not familiar with it.) When you open up the Windows Volume Mixer do you see your device? I've used multiple USB sound cards and Windows could always control the level. I'm also pretty surprised that you can be at the bottom of a 50k pot with too much level output. Does the pot control the volume at all? (I assume you have the pot connected correctly?)

I've already checked the usb drivers and they are up to date. I haven't checked if there are specific drivers available for this DAC, so I'll give that a try.

The 50k pot is shoddy at best, initially I thought it was just a bad pot. Only at the ends of its rotation it controlled the volume substantially, with the lowest part impacting the sound quality it weird ways. I've now been informed that 50k is way to much, and I hooking up a 10k to see if that works better. I also had some other strange issues with sound quality when I connected up my subwoofer as well. I made new thread about it in the analog line level section
 
Adapting L20D to +/-50v

Hi,
I have some L20D laying around, and a +/-50VDC SMPS as well.
I tried to connect these together, but (as expected) the L20D do not power up properly. The LED shuts of at a very low volume, so I expect that it is the OCP that kicks in.

Has anyone successfully modified a L20D to a lower voltage?
I have replaced the 1W resistors as following:
5k1 resistors to 3k3, and the 2k2 to 1k. This is according to L15D (and IRDAUAMP7-150). However, I still have the same issue. I suspect that I also need to replace the 75k resistor (R17 on the IRDAUAMP schematic) to 47k in order to have high side current limit (and drive to VB) correct. However, I can not figure out if I need to replace R12 and R18 as well? I still would like to have the 23A trip level intact to protect the IRFI4020H.

Is there other things I might have missed?

BR
Vidar
 
Hi Wieslaw,
the impedance are 8 ohm nominal. I have successfully driven these speakers with class D amplifier before, so I do not think this is the reason. Also, the clipping happens way before 1W output, indicating that there are some other issue.
I do believe that the issue are me trying to run an amplifier designed for 70v on a 50v supply. I just thought that I could modify it to a IRAUDAMP-150 by replacing some resistors (other posts on this forum indicate that this is possible).
However, I suspect I am missing some modification (or the fact that it is not possible to easily modify a L20D to a L15D when it comes to supply voltage).