Tried something today dealin with gain and lowpass crossover

[luvinthebass 5,000+ posts]

i have a walmart one, and it's most accurate at 60 hz cuz i measured a house outlet and it said 120 volts, but i used a 60 hz 0 dbfor my sub amp and it was easy to notice the distortion then i backed down again, the amp puts out 600 at 2 ohms and my sub only handles 400 so i just used the dmm till i got 20 volts then stopped, hope my sub lasts...

 

[xluben 10+ year member]

what subs/amp do you have?

sounds like you have absolutely no idea what you're doing.

setting gains with a -3dB tone will make actual music sound louder than 0dB

why do you have the low pass set to 60hz?

you should not use a 60Hz tone to set the gains if that's where the -3dB point is.

if your sub is actually wired to 2 ohms you'll be getting 200W with a 20V output.

 

[aaron7114 10+ year member]

Ive used 3 DMMs on my system. Set the amp to 40 volts with one DMM. Took the dmm and it showed 35 volts. Then I bought a new DMM at radioshack and it showed 56 volts.

 

[luvinthebass 5,000+ posts]

what subs/amp do you have?
sounds like you have absolutely no idea what you're doing.

setting gains with a -3dB tone will make actual music sound louder than 0dB

why do you have the low pass set to 60hz?

you should not use a 60Hz tone to set the gains if that's where the -3dB point is.

if your sub is actually wired to 2 ohms you'll be getting 200W with a 20V output.

i have a Kicker 600.1 and i have a kicker cvr 12'' dual 4 ohm wired for a 2 ohm load for my amp, so it should be 40 volts then? okay so what tone should i use then , 45, 50 hz? and shoudl i buy a DMM from radioshack as well?

 

[xluben 10+ year member]

yes to all questions.

you should probably be using a 40Hz tone for gain setting.

but i don't know why you want the low pass set so low.

unless your front stage has some serious output below 80Hz i think you're gonna have a big dip in midbass.

 

[luvinthebass 5,000+ posts]

k, 40 hz it is, new dmm it is too, and i'll put my crossover at 80 hz how's that after i set my gain, thanks for the help xluben //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[aaron7114 10+ year member]

what would be the differences in using 40 hz, 50hz, and 60 hz?

Also if I set my filters first then set my gain would I end setting my gain to high or to low?

 

[luvinthebass 5,000+ posts]

you'd be settin it to high,

on the frequency question: i guess you choose what frequency you want hte most output, i'm gonna try different ones and see which ones my amp puts out the most and use that one.

 

[xluben 10+ year member]

what would be the differences in using 40 hz, 50hz, and 60 hz?
Also if I set my filters first then set my gain would I end setting my gain to high or to low?

as long as the frequency is within the passband it shouldn't matter what you use.

how do you plan on setting the filters first? you need to reference them to the reference output voltage.

if you know what you're doing it can be done, but i don't think you know what you're doing.

you'd be settin it to high, on the frequency question: i guess you choose what frequency you want hte most output, i'm gonna try different ones and see which ones my amp puts out the most and use that one.

as stated above, the frequency you set the gain with shouldn't matter as long as it's within the pass band

if you have the SSF at 20Hz and the LPF at 80Hz the output signal will be -3dB at these points, but depending on the slope of the crossover it could be as low as -3dB at 40Hz (ie. with very shallow sloping crossovers they will overlap) if your crossovers are steep enough they won't overlap, but picking a frequency too close to either -3dB point could still be in the sloping portion (and could cause clipping in the true bass band region).

hope that made sense!

 

[luvinthebass 5,000+ posts]

as long as the frequency is within the passband it shouldn't matter what you use.
how do you plan on setting the filters first? you need to reference them to the reference output voltage.

if you know what you're doing it can be done, but i don't think you know what you're doing.

as stated above, the frequency you set the gain with shouldn't matter as long as it's within the pass band

if you have the SSF at 20Hz and the LPF at 80Hz the output signal will be -3dB at these points, but depending on the slope of the crossover it could be as low as -3dB at 40Hz (ie. with very shallow sloping crossovers they will overlap) if your crossovers are steep enough they won't overlap, but picking a frequency too close to either -3dB point could still be in the sloping portion (and could cause clipping in the true bass band region).

hope that made sense!

explain it more

 

[BassAddictJ 5,000+ posts]

this is an interesting thread so far.

 

[luvinthebass 5,000+ posts]

i'm learning alot in this thread.

 

[thch 10+ year member]

in short, filters (like lowpass or subsonic) affect mainly frequencies in the stop band -- the frequencies that are being rejected.

but they also affect frequencies in the pass band -- the ones you are wanting to play. they affect frequencies that are "near" the cutoff point more then ones "far" from the cutoff.

a given lowpass filter may be -3dB at 80hz (cutoff), -6dB at 160hz, -12dB at 320hz. but the filter would be -0.5dB at 40hz and -0.1dB at 20hz. (this is an example of a simple -6dB/oct filter)

different filters will transition differently. a subsonic filter with a varialbe Q (might be advertised as a SSF+bass boost in one) might vary between +-3dB at some given frequency in the passband.

from a mathmatical standpoint, it is probably best to test in the geometric mean of the SSF and lowpass cutoffs. aka (SSF * LOW)^0.5 . this gives you the center of the passband, which should be (but isn't garunteed to be) the closest to 0dB (neither boosted nor blocked).

The philosophy is to set the gains without filters. from this point, you can determine what affects the filters have and adjust accordingly. so long as the filters never boost the signal, you cannot* clip the signal.

*not true for actual music.