Ok, I just made some vids about setting gains w/ multimeter based on an amps rated output and the DCR (load) the amp will see.
I used 2ohm on a PG radial 600.1. Set then gains at 60hz to ~34.5v (just under the 'rated' 34.64v). I then addded a load to the amp, 2 RSd12's, and showed that even though the amp will most likely not clip at ~60hz but will at lower freq, such as 40hz.
I think you just wanted to play with your new scope
But seriously, may I ask what this is meant to prove? Your load is not constant, since the impedance of a speaker changes with frequency. If you hooked up a high power 2 ohm resistor and set the gain the same way, you would see a totally clean sine wave. This is also why speakers can't be used as a load when benchtesting amplifiers.
Again I'm not wanting to start anything here just wondering why you're doing this.
I'm only doing this to pretty much show what you just said. I have seen quite a few people swear to setting gains w/ a multimeter...saying 'YOUR AMP WILL NOT CLIP' if you do so.
I wanted to show that setting gains w/ multimeter will get you close, but the load will change w/ frequency so it can and will clip at different freq. Mainly at lower freq.
That, and I had some down time to play w/ the scope
Ok I get what you're saying. To have the amp always put out a 100% pure sine wave you would have to use the lowest frequency that would be played when setting the gain, which would be right above the SSF setting.
That said, 50 hz is what most people use. When playing frequencies lower than that, IMO the amplifier would not clip enough to cause damage to the sub(s).
At the end you here me say, "Do not set your gains by multimeter". That was not totally correct. I ment to something to this effect:
Setting your gain w/ a multimeter will get you CLOSE, but your amp will most likely still clip at some freq. You can start off by setting w/ the multimeter, but then listen to some tones and see it you hear clipping at any other freq. If you do, back off on the gain a little."
I agree you can set your gains with a multimeter and we have seen that below the frequency you set it to it tends to produce more below that frequency and I believe its because your usually setting your amp above your subs port tune and im pretty sure box rise is supposed to be lower closer to port tune with the sub hooked up....so taking that all into account you can eventually set our gain very well and possibly take advantage of this knowledge with car acoustics and port tuning choices ....just a quick thought
