setting gains with or without inline crossover?

[Goldenknob 10+ year member]

I'm wanting to set my gains with a voltmeter.. but between my H/U and my amp I have a Sony XEC-505 electronic crossover that splits the 4rcs's from my H/U to 6 channels to go to amps. making the channels 2 sub, 2 mid, and 2 high. should I bypass this to set my gains then hook it back up as normal?

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[cjjackson85 5,000+ posts]

Go through whatever you'd use during normal playback.

 

[Goldenknob 10+ year member]

thanks cj...

one more thought..

when setting the gains in this style.. is this assuming that your amp is putting out a clean un clipping signal?.. how can you tell if it is clipping?

 

[maylar 10+ year member]

With an oscilloscope. Otherwise you need to either set the output voltage conservatively (below rated output) or have faith in the manufacturer's ratings.

 

[Goldenknob 10+ year member]

heh.. sound advice.. thanks..

think I"ll visit the local shops and see what they would charge to check till clipping gain setting just to be safe... unless of course it would be super expensive.. then I'll just play it safe //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[theCybe 5,000+ posts]

You'll notice a jump on the DMM; For instance;

When gaining my BX1500d;

I wanted 1000w @ 2 ohm;

2000sqrt= like 44.72 something.

So, attached the meter.

If you twist the gain up, you might get a reading like 80.

Now, 80 * 80 = 6400 / 2 = 3200 watts. Obviously incorrect.

Clipped signal.

Gain a volt or two under your calculation.

 

[Goldenknob 10+ year member]

what we did (me and btmorris) we first gave it a nice fat 4 guage ground cable, from my smaller 14 guage. then played the 45hz test tone with no speakers hooked up to the sub amp, engine running.. my head unit was at 60/80 with bass and treble flat 0, had the crossover at halfway for the subs. was only getting about 17volts with the gain all the way up.. so we turned the crossover gain knob up to about 3/4 and the voltage shot up to about 50 or 60.. so we then turned the gain down.. we ended up with the gain at about 3/4 on the amp and the gain on the crossover at full with the boost on the crossover at 3/4 and the freq at 80 and below. this setting achieved a voltage of 31.6 out of one channel of the amp.

to make sure we did the formula right

Sqrt(2*500)= 31.6

since I only have one gain knob then this set both channels for each sub..

as stated by others.. it did seem a bit quieter, but with a tiny adjustment up to 66/80 it got plenty loud.

and I left freedom to be able to adjust the crossover gains a little higher at a lower volume if I want more bass and less mids and highs.