[edmond]

Jason,

I've just tried your method.    I swap the L/R input to my IA-7E but the outcome is the same as before - music only comes out from the L channel when start-up at level 1 LED volume and the R channel just gives hissing noise.    Until I turn the volume up to level 2-3 LED, music then comes out from the R channel too.    After that, everything works normal even if I turn the volume back to level 1 LED again.    Both L/R channels sing.    Sound image is at the centre between two loudspeakers.    Obviously, the problem is not related to the input signals.    I'd say, when start-up, the R channel of my IA-7E is much less responsive than the L channel, because it requires stronger signal to activate the self-oscillation.    If the L/R amplifying modules are identical, why is there so big difference in start-up?    What is your opinion?    Is it defect?   


Edmond

[rustydoglim]

I already explained the behavior:
"The principle of Nuforce amplifier is based on self-oscillation with the speaker as part of the loop. The self-oscillation requires input signal around 20mV (+/- 2mV) to start. Due to the analog based design, speaker’s impedance and natural variations in components’ values, the self-oscillation might start with different input signal strength and delay. After the oscillator has started (within the initial 3 seconds), it will continue to oscillate even when input signal is not present. This design characteristic resulted in different startup input signal strength or delay time observed from amplifier to amplifier (it could be different between two channels within an integrated amplifier)."

Your test further proved that there is nothing wrong with the amp. After the ONE TIME startup, you turn down the music at level 1, and you hear that the L/R signal sounded right. You also switched the L/R input and the behavior is the same. Are you playing the SAME music for the test? Could it be that the right channel has very low signal at the beginning of the music. Try different tracks.

[edmond]

Your test further proved that there is nothing wrong with the amp. After the ONE TIME startup, you turn down the music at level 1, and you hear that the L/R signal sounded right. You also switched the L/R input and the behavior is the same. Are you playing the SAME music for the test? Could it be that the right channel has very low signal at the beginning of the music. Try different tracks.

For the test, I played different kind of music/CDs and even connected the IA-7E with other sources, say TV and DVDP.    I also switched the L/R input several times so that I don't think the signal strength to the R channel was always lower.    However, the R channel was always less responsive.    It always needed me turning up the volume to level 2-3 for its startup.    On the other hand, the L channel was much reliable and always able to start up at level 1 volume.

I already explained the behavior:
"The principle of Nuforce amplifier is based on self-oscillation with the speaker as part of the loop. The self-oscillation requires input signal around 20mV (+/- 2mV) to start. Due to the analog based design, speaker’s impedance and natural variations in components’ values, the self-oscillation might start with different input signal strength and delay. After the oscillator has started (within the initial 3 seconds), it will continue to oscillate even when input signal is not present. This design characteristic resulted in different startup input signal strength or delay time observed from amplifier to amplifier (it could be different between two channels within an integrated amplifier)."

Yes, you've told that the self-oscillation might start with different input signal strength and delay, around 20mV (+/- 2mV).    But the test showed that the L channel can always start up at low volume level 1 while the R channel is necessary to start up at high volume level 2-3.    So the question is the BIG difference in start up volume between the two channels.    Why so big different?    Do you still think it is normal, no defect?    Do all other IA-7E have the same problem, big difference in startup volume between 2 channels?   

[rustydoglim]

Why so big different?    Do you still think it is normal, no defect?    Do all other IA-7E have the same problem, big difference in startup volume between 2 channels?

Yes, they have the same characteristics (not problem ).  If you try 10 IA-7, you'll find the startup characteristics different for some of them. Because this is only happening at the power up time, less than 1% of people pay attention to it. As you have tested, AFTER the startup, the sensitivity of both channels are the same.  If it doesn't affect your listening experience, how can you call it a defect?  This is not limited to IA-7, same behavior happens to all the monoblocks.  It is a startup behavior.  If you want further prove, AFTER the startup, measure the output of the L/R channels using the same sine wave input signal, regardless of volume level, L and R has the same gain.

[edmond]