Can this amplifier be bridged?

lalalala · 26th April 2011, 02:48 PM

Hi,

I find this class D amplifier kit on ebay:

TDA8920 CLASS D Audio Power Amplifier AMP Kit 100W X2 | eBay

It seems very inexpensive (if it works). Anyone knows if this amplifier can be bridged?

Thanks.

LAJ · 26th April 2011, 04:01 PM

The concept of bridging requires that one of the inputs (of a stereo amp) be inverted. This can easily be accomplished with balanced inputs but its my guess that this amp probably has unbalanced inputs.

lalalala · 26th April 2011, 04:29 PM

You are right. The input has three terminals (-, + and GND), if that is what you mean by "balanced input". What if I connect one input to the - and +? Is that equivalent to bridging it? Thanks a lot.

stratus46 · 26th April 2011, 04:39 PM

Quote:

Originally Posted by LAJ

The concept of bridging requires that one of the inputs (of a stereo amp) be inverted. This can easily be accomplished with balanced inputs but its my guess that this amp probably has unbalanced inputs.

An inverter is a mystery? The limiting factor is output current capabilities.

G²

macboy · 26th April 2011, 05:18 PM

This definitely can be bridged, but you will need to provide an inverted signal at one input (either L or R). The +/-/GND "input" that you see is the connection for the power supply. The input signals are on the little white connector.

If you look up the TDA8920 you will see that it is a 2 x 50 W chip (or 2 x 80 W depending on which datasheet you find), and it can be operated in bridged mode. In stereo mode and 8 ohm load, the output at 0.5% distortion is only 30 W x 2, and rises to 39 W x 2 at 10% which isn't music any more, it's garbage. With 4 ohms, it can do 80 W x 2 at 10% distortion. In mono bridged mode and 8 ohms, it manages 79 W at 0.5% and 100 W at 10%. My point is, don't believe for a second the "100 W x 2" in the auction title. It is a lie. And if they lie about that.... what else? Do you trust them enough to send your money? And do you even want this if it does only 30 W/ch not 100 W?

26th April 2011, 02:48 PM	#1
lalalala diyAudio Member Join Date: Aug 2010	Can this amplifier be bridged? Hi, I find this class D amplifier kit on ebay: TDA8920 CLASS D Audio Power Amplifier AMP Kit 100W X2 \| eBay It seems very inexpensive (if it works). Anyone knows if this amplifier can be bridged? Thanks.

26th April 2011, 04:01 PM	#2
LAJ diyAudio Member Join Date: Mar 2008 Location: Atlanta Ga. USA	Probably not The concept of bridging requires that one of the inputs (of a stereo amp) be inverted. This can easily be accomplished with balanced inputs but its my guess that this amp probably has unbalanced inputs.

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26th April 2011, 04:29 PM	#3
lalalala diyAudio Member Join Date: Aug 2010	You are right. The input has three terminals (-, + and GND), if that is what you mean by "balanced input". What if I connect one input to the - and +? Is that equivalent to bridging it? Thanks a lot.

26th April 2011, 05:18 PM	#5
macboy diyAudio Member Join Date: Oct 2003 Location: Ottawa, Canada	This definitely can be bridged, but you will need to provide an inverted signal at one input (either L or R). The +/-/GND "input" that you see is the connection for the power supply. The input signals are on the little white connector. If you look up the TDA8920 you will see that it is a 2 x 50 W chip (or 2 x 80 W depending on which datasheet you find), and it can be operated in bridged mode. In stereo mode and 8 ohm load, the output at 0.5% distortion is only 30 W x 2, and rises to 39 W x 2 at 10% which isn't music any more, it's garbage. With 4 ohms, it can do 80 W x 2 at 10% distortion. In mono bridged mode and 8 ohms, it manages 79 W at 0.5% and 100 W at 10%. My point is, don't believe for a second the "100 W x 2" in the auction title. It is a lie. And if they lie about that.... what else? Do you trust them enough to send your money? And do you even want this if it does only 30 W/ch not 100 W?

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