Hey guys,

Just wondering if this is a reliable way of setting amp gains as to not overdrive a subwoofer..

Set HU to 3/4 full volume with all processing off.
Connect voltmeter to speaker outputs from amplifier.
Play a sine wave (0dB, 50hz), and turn the gain up or down until the voltage at the voltmeter = sqrt(PxR)

Where P = RMS power of subwoofer in Watts and
R = resistance of subwoofer in ohms.

I'd use my ears, but I'm not very good at hearing distortion when I can't turn the rest of my speakers down (or in general maybe..)

So in my case (which I'll try tomorrow).
sqrt(350x4) which is approx 37V.

Thanks guys

Disconnect your other speakers from the amp and just set the gain levels for the sub without them on. You don't need the other speakers on. You should be able to pick up the distortion fairly easy then.

Disconnect your other speakers from the amp and just set the gain levels for the sub without them on. You don't need the other speakers on. You should be able to pick up the distortion fairly easy then.
The others are off the HU, the amps just for the sub :(
I was also thinking not to set it so it gets exactly 350, but maybe 325 or 300

EDIT: I know this topics been done to death, but I'd rather use science over just listening to it.

Ha i never reliased you could do it that way. How far can you turn gain up before it becomes to dangerous.

I have pione 300w 250rms(Its rms right?) and a 800w sub 250rms. Is half good?

Ha i never reliased you could do it that way. How far can you turn gain up before it becomes to dangerous.

I have pione 300w 250rms(Its rms right?) and a 800w sub 250rms. Is half good?
No idea haha, I think it depends on input voltage aswell.
Note: You can't do it with just any voltmeter with RMS, most multimeters measure in Vavg instead of Vrms, and you have to convert any calculations you make into Vavg before you go setting stuff. (Pretty sure its avg.. correct me if I'm wrong)

you can set level set using a multimeter but i personally still recommend to everyone that asks to to see something with a scope and get them to do it.. as im not too demanding of loudness these days i just set it where im happy with it and leave it at that, btu if you want to get the most from your system then definently get them scope set

you can set level set using a multimeter but i personally still recommend to everyone that asks to to see something with a scope and get them to do it.. as im not too demanding of loudness these days i just set it where im happy with it and leave it at that, btu if you want to get the most from your system then definently get them scope set
Yeah, I had a go with the DMM today, and dayyumm.. that was waaaay too much bass :shock:
I'll just leave it where it was, was mainly just checking that it was safe where I had it.

you can set level set using a multimeter but i personally still recommend to everyone that asks to to see something with a scope and get them to do it.. as im not too demanding of loudness these days i just set it where im happy with it and leave it at that, btu if you want to get the most from your system then definently get them scope set

There is that,

Also, Sycrat - what out for you tuning using a Multi for 'perfect world' conditions.

Yes, technically your calculations are correct, if everything in the sub was perfect.

However there's quite a few DIY youtube video's of tuning with a multi showing that your amp will still clip, or your sub will try and produce a square wave when set with a multi (distort).

While theoretically correct, your ears are still a better instrument to tune by as every electrical component is built in with a bit of 'give', where as you are tuning as if every electrical component was as per the spec sheet.

If you are set on tuning via multi, tune it, then take off 10% from the gain.

Nothing wrong with a bit of clipping, your ears will pick up the distortion if it's around 10% very easily. Just don't ask your amp to send a squareish sine or else you will have a burnt coil in no time.

Only easy way around it is to get tuned by a pro or buy an amp with inbuilt clipping indicator.