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Old 20th February 2011, 01:28 AM   #861
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Hi to all!
One question!?

My amp has +-60V DC (transformer 800VA). On output have 40V AC with no distorsion(measured with osciloskope). swishing freq. is around 240KHz(C1 100pF,20uH on output with 1uF cap) Output transistors are IRFP240(gate resistor 20ohms).

That means with 40V AC on output, with 4 ohms load I can have 400W RMS.

But is not LOUD, when i conect him on speakers, as it has 100W and not 400W.

My output filter is very poor (EE33 ferrite core from atx smps with 18 turns and 1mm gap) and 1uF capacitor. Its hot on half power.

Maybe output filter is problem, i dont know

How do I resolve this?
Please Help, Thanks
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Old 20th February 2011, 01:33 AM   #862
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Quote:
Originally Posted by Dzony988 View Post

My output filter is very poor (EE33 ferrite core from atx smps with 18 turns and 1mm gap) and 1uF capacitor. Its hot on half power.

Maybe output filter is problem, i dont know

Please Help, Thanks
Output inductors on class d amps is a minefield.

I started off with a power inductor and it reached 120 degrees c !!!!!
These power toroids arent meant to be used with class d, the yare meants for mains filtering.
They will also saturate and pass a lot of current and trip up some class d chip over current detect.

I bought a t106-2 toroid and wound on it about 30 turns of 18 SWG enamel magnet wire and it runs cold.
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Last edited by nigelwright7557; 20th February 2011 at 01:39 AM.
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Old 20th February 2011, 01:39 AM   #863
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With better output inductor, will be my amp louder then now?
Whay output inductor is a problem and my amp is not loud?

What is maximum power with T106-2?

Thanks for replay and Regards
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Old 20th February 2011, 01:44 AM   #864
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>With better output inductor, will be my amp louder then now?
I am not sure.

>Whay output inductor is a problem and my amp is not loud?
Depends why the amp isnt playing loud.

>What is maximum power with T106-2?
I am running 500 watts peak.

I would give the t106-2 a go and see what results you get.

Are you sure you are getting 100% modulation ?

Maybe you just need to drive it harder or adjust the gain of the amp.

Remember that 400watts isnt a lot more than 100 watts as you need ten times more power to be twice as loud.
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Old 20th February 2011, 01:51 AM   #865
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I'm not sure for modulation, i dont have distorsion or swishing noice, sound is very good, clear, full audio spectar, bass is very clear and strong but amp is not loud on full power.

40V on output, 1KHz sine , i get with 1,68V on input. With 4 ohm load, voltage drop on uotput is 0.8V (~39V on output,theoretically is 400W)
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Old 20th February 2011, 09:29 AM   #866
luka is offline luka  Slovenia
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Quote:
Originally Posted by nigelwright7557 View Post
>With better output inductor, will be my amp louder then now?
I am not sure.

>Whay output inductor is a problem and my amp is not loud?
Depends why the amp isnt playing loud.
Loudness has nothing to do with output power. Only question here is, do you get 400w out or not, that being said, you would need to know voltage, that you do, and current going to speaker. If its not loud as you wanted, could be many things and speaker box is one of them
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Old 20th February 2011, 05:56 PM   #867
paul14 is offline paul14  Romania
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Which pcb is better? I see that one of them has that protection circuit with NE555.

http://i66.servimg.com/u/f66/12/46/21/31/ucd_v510.png
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File Type: pdf IR2110 UCDcopper.pdf (52.2 KB, 541 views)
File Type: zip ucd amp.zip (133.7 KB, 515 views)
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Old 20th February 2011, 06:20 PM   #868
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This one with NE555 is mine board and is bad. Protection dont work and transitors 2N5401 has wrong pinout.
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Old 20th February 2011, 06:24 PM   #869
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Question for all

What are you think about this output coil

I use 2 cores T106-26 gaped with 1mm gap and 22 turns. I have very litle heat on it, its works but i want your opinion

How meny turns i need on this "core" for 20uH. How to calculate it?

thanks
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File Type: png core.png (13.5 KB, 1025 views)
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Old 20th February 2011, 06:27 PM   #870
paul14 is offline paul14  Romania
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Thanks for reply. So, the "battle" remains between the pcb from pdf file and pcb from that photo.
Personally, i`ll do the pcb from pdf file, but adding a ground plane on top.
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