Equal power

Mike Kozak

How can I tell if I am getting the same amount of power from each channel with my Technics SA-600 receiver? What do I need to tes it and how would I do this?

Thanks everyone.

mhardy6647

You can get an estimate of output power with a frequency generator (there are s/w tone generators for your sound card) a DMM or VTVM and an oscilloscope. Put a suitable, nonreactive dummy load resistor of known resistance (e.g., 8 ohms) on each channel. Feed one channel, say a 1000 Hz signal and observe the waveform on the scope. Increase the drive voltage ('volume') of the tone. When the tops of the sine wave start to flatten, measure the RMS AC voltage and you can calculate the power. Repeat for the other channel.

The "right" way to do it would also include a distortion analyzer.

The old FTC spec is more complicated than that, and is for both channels driven at once.

Bear in mind that the SA-600 may not be too happy putting out full power at any frequency for very long.

EDIT: For a quick and dirty test, use white or pink noise (FM interstation noise with the muting "off") and use the balance control to compare perceived loudness from each channel. This will not isolate the issue (if any) to the amplifier, of course (and it's completely qualitative).

ShinAce

Are you wanting to test the maximum ouput power of each channel? If so, you got the full answer above.

If you want to make sure each channel is even, then you need a test tone and a voltage meter.

My amp is a basic two channel amp with individual volume controls. I run the amp 'full tilt' to make sure the pots don't cause an imbalance.

If I wanted to double check, I'd run both speakers at the same time while each channel gets a 120 Hz tone. 60Hz is ideal but your speakers won't love that. It doesn't even have to be loud enough to be audible, but a bit of volume makes you feel more confident in your measurement. I go with a low harmonic like 120 Hz or 180 Hz to get accuracy out of the meter.

You can get test tones as mp3 and burn them onto a cd. Play the tone, with the speaker connected or not, and measure the AC voltage. Compare with other channel and adjust volume/gain to match. A mismatch of 1% should not even be corrected.