Oscope gain setting gone wrong

[rocknwoo]

Hey guys just got my tpi 440 oscope today and started to Set the gain on my arc audio 4000se amp. So first I took the speaker wire out and connected my oscope leads in set the volume right and played a 50hz 0dB tone, set the gain before clipping my oscope was matching my amp clipping light so everything seemed perfect. Hooked my speaker wires and played some songs it was way lower then before so I turn the gain up to my liking and the clipping light on my amp was good. So my question is, is it better to set gain with oscope with the speakers conneted or did I do something wrong. Appreciate any advice

[alan412]

use a -6db tone at 40-50 Hz

[Guest]

box rise. makes the resistance of the woofers go up. thats why some songs sound quieter.

[rocknwoo]

With the oscope connect my amp(4000W @1ohm) it clipped oround 72vac so then using an oscope isn't that acurate?

[rocknwoo]

And also when connecting an oscope what load is the amp seeing

[oc_wicked]

With the oscope connect my amp(4000W @1ohm) it clipped oround 72vac so then using an oscope isn't that acurate?

it prob jus means you're getting a little more power than 4k but i might be wrong!!

[rocknwoo]

I don't have a clamp to measure my current but 72vac seems really low to equal 4K. So it's seem like measuring with the speaker wires connected would be mor acurate but not sure

[alan412]

try it out and let us know . i'm curious to know what the difference is between scoping the amp with a load and without one.

[Guest]

guys...the reason his woofers sound quieter is because the box raises the impedance of the woofers. lets say you have a 1 ohm final load, after you put the woofers in the box and hook it up to the amp, your amp could well be seeing 3 ohms and up on some frequencies. your woofers are ALWAYS changing impedance. they are never truly 1 ohm, 2 ohm, 4 ohm etc. hook up a dmm to your woofers and push on the cone and youll see the impedance jump around. this is exactly what they do when they are on your amp.

if that clipping indicator on the knob is as accurate as you say it is, then bump up the gain a tad and dont let that light come on at all and you should be fine.

[ben29555]

use a -5 or -6 db tone. their is no music that you will be playing thats that loud loudest is usualy 25 26db some bass test can be as higer