SFX Class D subwoofer amplifier modification

[Tekko]

I use IRF640, the coil is a T94-2 with around 45 turns of 0.5mm or something wire on it on it.

The power i dunno.

 

[sagarverma]

The power i dunno.

what is the + - Vcc applied?
by the listening impressions,do u think that it is powerful enough to boom a subwoofer?
have u tried paralleling the mosfets?
the two rectangle boxes,i suppose they are power supply + - V?


Sagar

 

[Tekko]

I use 2x19v rails, i have driven my 2ohm subwoofer with it and the drivers bottomed out when playing loud.

 

[sagarverma]

thanks for this
i will definately build it up in next few days

Sagar

 

[Tekko]

One problem with it is that it beeps faintly on a freq that sounds like 2-5khz but that can prolly be fiwed with the output filter and adding of a post filter feedback and error amp.

Tho the beep is not heard with a subwoofer connected.

 

[sagarverma]

beep
plz draw the 'proposed cure'' schematic.
can i use IRF540 with this amp of yours?
how high can the +-V go,ie the safe max. with 640 and 540?

Sagar

 

[Tekko]

I have not tried any higher than 2x19v.

I don´t know a cure yet but i´ll check out for one.

 

[sagarverma]

whatever be it,as u are saying it plays and it plays good.
i will make it soon and use IRF540 and +-27V supply.

Sagar

 

[Tekko]

You may want to replace the IR2111 with something better, like IR2011 that is designed for class d audio.

For IR2010, IR2110, IR2113, just add a second comparator but wire is opposite to the one in the schem, swap the inputs.

 

[sagarverma]

getting these ic would be a real pain in ***.
i will have to go to the big main mkt of Delhi for that .
neway,is there a way to order free samples??

Sagar

 

[Tekko]

I dunno, never tried.

 

[sagarverma]

that means a long trip to that dingy market.
will make this amp for sure,its so simple,the catch is so irresistable!

Sagar

 

[Tekko]

Hold your horses! There is a fault in the schemo.

Heres a corrected one:

 

[sagarverma]

screechhhhhhhhhhh!

what r u saying now in the end when i am all set to make it as my first class d amp?
R U sure that the new scheme u post is correct?
BTW have u done it on PCB?
can u post the pics of finished amp.

Sagar

 

[Tekko]

Amp pics on request:

 

[Tekko]

closeup pulse width modulator:

 

[Tekko]

And output stage:

 

[sagarverma]

neat work
and that prize of all in a class d amplifier...NO HEATSINK!
i will make a pcb and then go ahead.
i will try replace TLC393 with a opamp comparator.
using two dual opamp chips,2 opamps for the main scheme and one will be wired as a comparator and other as a preamp.

Sagar

 

[Tekko]

You cannot use opamps as comparator, it wont work.

I used LM393N and it works nicely.

 

[sagarverma]

thanks for the warning but l i had wired opamp as a comparator before and it worked well.
but as u saying,so i will use 393 family itself

Sagar