Thanks for that; is such high distortion typically considered acceptable in subs? I know low frequencies arent as affected by THD but this seems really high.
Some time ago I saw a video, it was either Audioholics or Rocky Mountain, suggesting that THD in subs could hit 10% before the casual listener noticed but as someone coming from a 2 channel background that's a bit hard to swallow. I know I shouldn't expect miracles in my use case, but just broadly speaking does that seem accurate?
There's obviously no single, absolutely correct answer to the question "how much distortion is audible?", but it's definitely the case that nonlinear distortion below a couple of hundred Hertz is far less audible than distortion higher in frequency.
Figures like 10% don't mean much, because what matters is the frequency of the distortion relative to the fundamental, and the absolute level at the listening position. Having said that, I would imagine 10%, unless particularly pathological, would be at least very difficult to hear at moderate listening levels in the 20-80Hz range.
In any case, I'd find it very hard to believe any distortion of any kind below 1% would be audible to anyone below 80Hz, which would place this amp squarely in the safe category for sub duties.
If you want to find out for yourself, you could try to comparing a distorted signal with an undistorted signal to find out what's audible to you, with something like
this piece of software, using and a pair of headphones that you know is capable of reproducing low frequencies.
Play a WAV file through the software, set a low-pass crossover at 80-ish Hz, and then adjust the slider to give you your desired % THD/IMD (you could start with 10% or 20% and work your way down). Obviously, you'll only be hearing the bass (+distortion) in this case, so if you can't hear distortion under these circumstances, you won't be able to hear it when the rest of the signal is also present (the more signal present, the more any distortion will be masked).
If you think you can hear 0.5% distortion, the software allows you to blind test yourself to make sure you're not imagining it (NB: it's important to have extremely low latency with this particular program, otherwise the brief gap in playback will give it away).
erformance. Thanks!
