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Old 15th April 2013, 01:10 PM   #1
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Default Inexpensive classD amp ?

I came across the following on Ebay:
Assembled L25D Digital Audio Amplifier 250W 250W 8ohm IRS2092 IRAUDAMP7 Class D | eBay

Has anyone seen/purchased one of these and/or, is the item real ?
That is 50 bucks for 2 channels ?
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Old 15th April 2013, 01:24 PM   #2
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Why wouldn't it be real? It's not that cheap.

Note that you have to provide a power supply.
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Old 15th April 2013, 01:34 PM   #3
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Do NOT NOT NOT NOT buy that one, its rated to an absolute minimum load impedance of 8 ohms absolute minimum!!!

Try it on 4 ohms and it will blow up in your face, and no you cannot simply lower the rail voltages as the load impedance limitation lies in the mosfets themselves, also the IRS2092 has a undervoltage lockout so it wont even start if the rail voltages are below 2x55VDC, and no you cannot change this as its a combination of several resistors and zener diodes that are also part of other functions meaning change one resistor value and u have to recalculate pretty much every resistor on the board.

Not to mention beeing sold on ebay there is a 99.9% risk of the components beeing counterfeit = the thing is essentially a armed bomb.
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Old 15th April 2013, 01:39 PM   #4
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Quote:
Originally Posted by Tekko View Post
Not to mention beeing sold on ebay there is a 99.9% risk of the components beeing counterfeit = the thing is essentially a armed bomb.
There are plenty people on the forum who have used these cheap IRS2092 boards without incident.
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Old 16th April 2013, 10:51 PM   #5
MrSlim is offline MrSlim  Canada
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Quote:
Originally Posted by Tekko View Post
Do NOT NOT NOT NOT buy that one, its rated to an absolute minimum load impedance of 8 ohms absolute minimum!!!

Try it on 4 ohms and it will blow up in your face, and no you cannot simply lower the rail voltages as the load impedance limitation lies in the mosfets themselves, also the IRS2092 has a undervoltage lockout so it wont even start if the rail voltages are below 2x55VDC, and no you cannot change this as its a combination of several resistors and zener diodes that are also part of other functions meaning change one resistor value and u have to recalculate pretty much every resistor on the board.

Not to mention beeing sold on ebay there is a 99.9% risk of the components beeing counterfeit = the thing is essentially a armed bomb.
Sounds like you tried to do all those things and had a Massive Fail, maybe you should stick to the recommended parameters.. or should have bought the L15D instead( which works wonderfully for me thank you very much)

The OP isn't asking about any of the points you raise.. and like I said, run it within the parameters recommended by the designer, and you'll probably be fine.

*removed info about Sure board.. read about some reliability issues on another thread*

Last edited by MrSlim; 16th April 2013 at 11:03 PM.
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Old 17th April 2013, 08:50 AM   #6
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Another good deal:

2 x 100W Class-D Audio Amplifier Board TDA7498 - Black
Click the image to open in full size.
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Old 17th April 2013, 09:34 PM   #7
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I got one.
Sure sent me their board with seven SMD 220/50 electrolityc caps instead of regular you can see in the photo. The bass output is weaker than what I get from TDA7492 with regular 220/50's. The high tones are a little bit better and cleaner, though. I also replaced the input and filter caps in both amps.
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Old 18th April 2013, 03:13 AM   #8
Lo_Tse is offline Lo_Tse  Canada
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Quote:
Originally Posted by Tekko View Post
Do NOT NOT NOT NOT buy that one, its rated to an absolute minimum load impedance of 8 ohms absolute minimum!!!

Try it on 4 ohms and it will blow up in your face, and no you cannot simply lower the rail voltages as the load impedance limitation lies in the mosfets themselves, also the IRS2092 has a undervoltage lockout so it wont even start if the rail voltages are below 2x55VDC, and no you cannot change this as its a combination of several resistors and zener diodes that are also part of other functions meaning change one resistor value and u have to recalculate pretty much every resistor on the board.

Not to mention beeing sold on ebay there is a 99.9% risk of the components beeing counterfeit = the thing is essentially a armed bomb.
I noticed on the picture of the board (following the link in the first post) the marking LJM_LJM. I have read from other threads in the forum that there are "copy cats" of the same amp floating in EBay that used cheap/fake parts. So buyers beware. Apparently, there are only 2 EBay dealers that are selling real LJM stuffs supplied by the shop of LJM. LJM posts in this forum once in a while about some of his designs.

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