****, -6db test tone? Why do you recommend that? So that bass in lower quality music is still audible? Granted, you can always turn down the sub out on higher quality songs. I'm just curious. I've never read setting the gain with anything lower than -3.
Yeah, rememember, even if you set it with -6 tone at 0 on your sub output you can ALWAYS turn it down. If you use a 0db tone, well, as the say with any form of amp manipulation, it's alway better to cut than boost. -6 gives you plenty of headroom for playing tracks where the bass isn't that loud, but it needs a boost. -3db is generally the peaks of most bass heavy songs basslines. So if you set gains at -3 At that point, you won't be clipping except for brief periods where it goes above -3, which is pretty rare, but you'll also only be extracting 1/2 the amps power or less over most other periods. By going with a -6 tone, you get a bit of clipping on the -3 peaks, and double your amp power everywhere else. Given the dynamic range in most music, you get alot closer to at least using 1/2 your amps potential at all times. -6 is as high as I go, any higher and you will run into heavy clipping if you don't watch your bass output and adjust as needed. Regardless of how it' set, even if he sets the way I said with -6, I'd suspect he'll end up running the HU at - something on the subwoofer output most of the time, maybe -2 or -3. If he wants to go up to 0 for a song that should be fine, as always, if it stops getting louder, quit turning it up, that's how you can tell you've clipped too much generally. I've never seen anyone blow a woofer by clipping that really knew what they were doing. Stops getting louder, stop turning it up, so simply, yet very effective. -6 tones, so a 2:1 gain overlap, tends to maximize your amps output overall, at worst moderate clipping on very heavy songs, where common sense should say turn it down a hair for this one.
I'm a SQ guy most of the time, but I have basshead tendecies, so I set my gains differently than most. I set my gains so that with my subwoofer output all the way down, I have a nice blended SQ setting. Generally that gives me ALOT of headroom on the top end of my volume knob. Probably akin to -6 gain setting, maybe a bit more. Regardless, that way I blend at the earliest point possible and can use the rest for gain depending on the song. Lol, for example, there is a version of Celine Dions my heart will go on with almost "in the air tonight" style bass, but it's actually part of the song (I think it's around 25hz though). Unless you have alot of gain knob left though, boosting that up to basshead levels can be hard.
Regardless never forget, a noob will say a gain is a volume knob. An experienced CA.com enthusiast will say "no it's to match the hu to the amp".. Someone who actually knows wft they are talking about realizes that the noob is actually closer to the truth! Gain knobs are a volume knob, but they are to set the volume of 1 speaker in relation to another! Think about that for a second and it should make perfect sense. Some setups are more effecient than others, some speaker are more effecient than others. My horns for example, cannot be set with a test tone. If my horns ever recieved anywhere near RMS power from my amp, they'd destroy my ears (75 watts on 111db/1w/1m. The gain is there as a volume knob. Yes it uses the relationship between the HU and the amp, but that's not the intended goal, the absolute reference for the whole process is the sound. You want things to go up in volume as it sounds correct to you. However, that's a moving target for alot of people since different music requires different setting, generally on the bass settings especially. Combine that with different recording quality and the general need to be fairly loud on anything, and you see the need for aggressive gain setting. Works with mids and highs too. Most setups in most cars, setting gains with tones as most do, wouldn't play classical music worth a ****, it's too quiet. Any well recorded music will sound like crap with 0db tones. It's too far below the reference most of the time to get real output from it.
Anyway, one of my uncles did pro audio setups in clubs, concerts, studios, etc for many years. When I told him about DMM's and Oscope for gains he looked at me like I was crazy. It was when I first got into audio around 16 and this is basically, what he told me. Since then I've learned ALOT, but that has been on of the those things that has remained true.