Amp Woes

[chewie]

hey everone. a freind just recently bought a hifonics brutus bxi 2006 2000 watt rms amp and a cerwin vega stroker 15. dual 2 ohm voice coil. 0 guage wire ran from battery to battery and battery to amp/ground . big three were also upgraded.

has a 600 size kinetic battery in the trunk and voltage drop is not an issue. never measured lower than 13.2 v dc while bumping and sitting at idle

set his amp for breakin did around 12 hours or so of it. and then i turned the amp up for daily use.

no clipping or distortion was heard. sounded SUPER CLEAN and loud to boot. but the speaker would heat up really bad. after about two mins of playing any song.

after talking to a rep at cerwin vega. they said that that speaker should NOT get hot AT ALL. and the amp could be putting out dc voltage. (causing heat buildup) well the other day i guess while he was listening to psst by snoop dog. the voice coil came unwound. and it smelt like burnt epoxy

well what im trying to ask is how can i test the amp to see if its putting out dc voltage?

(my common sense tells me put a dmm on the outputs without a speaker and set the meter to dc and bump a song and watch to see what it puts out ) should it read anything on the meter when set to dc? if it reads anything. even 1 v dc is that bad?

i mentioned the ac voltage chart for setting gain to cv and they said theyve never heard of that. is it safe to set my gain like that?

also the speaker was in the optimum enclosure that cv called for 4.0 cubic feet tuned to 40 hz. is it bad to play the speaker below or above box tuning? somone mentioned that that was a spl box and not a daily use box.

somone please take me to school on these things.

for the record. the speaker was VERY loud. and sounded VERY clean. while it lasted.

good thing its rebuildable.

Edited July 16, 2008 by cerwinvega

[chewie]

kinda need a fast awnser about how to check to see if the amp is putting out dcv

[David]

sounds more like a box issue, how much did the woofer move while playing music?

and amp will put out a DC voltage when clipped, and if the gains where set correctly you shouldnt of had any clipping

[chewie]

sounds more like a box issue, how much did the woofer move while playing music?

and amp will put out a DC voltage when clipped, and if the gains where set correctly you shouldnt of had any clipping

the box was the optimum enclosure for the woofer. the woofer was movin but didnt look like it was over exerting itself

but if the gains are set properly will the amp put out dc voltage at all?

also this amp was bought used. from some guy who didnt know what he was doin. so its probably damaged

how can i check for dc output

[Boon]

You need an oscilloscope to check accurately for clipping, so you can see the output of the amp.

Otherwise just set the gain according to the RMS/Voltage chart on here. Chances are it's clipping the living hell out of it at the moment.

Other causes of clipping are crappy source material (bad mp3's are often clipped) or a crappy headunit that clips its outputs before full volume - then the amp just makes bigger clipping :S

[chewie]

You need an oscilloscope to check accurately for clipping, so you can see the output of the amp.

Otherwise just set the gain according to the RMS/Voltage chart on here. Chances are it's clipping the living hell out of it at the moment.

Other causes of clipping are crappy source material (bad mp3's are often clipped) or a crappy headunit that clips its outputs before full volume - then the amp just makes bigger clipping :S

i can ususally detect major clipping with my ears. the head unit is alpine so i have a feeling no worries tehre.

ive setup many systems. and have only had this issue on this one.

so its tellin me either the amp is damaged and putting out dc voltage. causing heat buildup.

btw tried another speaker on it. and guess what. runs hot. no matter how i set it. amp runs super cool though

[Boon]

Maybe the amp has some DC offset issues or something.

Sounds like the amp may indeed be faulty - when you power the amp on does the speaker 'pop' either in or out and stay in the position?

[Colin - STAPUFT]

i can ususally detect major clipping with my ears. the head unit is alpine so i have a feeling no worries tehre.

ive setup many systems. and have only had this issue on this one.

so its tellin me either the amp is damaged and putting out dc voltage. causing heat buildup.

btw tried another speaker on it. and guess what. runs hot. no matter how i set it. amp runs super cool though

It is pretty hard to detect minor audible clipping on a sub. If you get into crazytown with the clippage, you can hear it, but even a small amount of clipped signal is still DC sent to the sub.

Might be bad signal from your head unit being sent to the amp or could be the amp even if you set the gains with a digital multimeter.

As has been said, you really need an o-scope to check to see if that amp is clipping.

[chewie]

well tonight i ran a test

put the gain to 1/4 and turned bass boost down.

ran a few songs and all the results were near the same.

stayed at .43v dc constant and then would spike to about 3.48 volts dc when hard basslines would hit also hit different volts all the way up to 3.48

also during startup there is no humming or feedback or movement of the speakers.. thats the first thing i looked for when we bought it used.

i usually turn up the gain until i can hear distortion and then back it down 1/6th of a turn i will start setting with a multimeter though.

its a alpine head unit and new rca cables. ran opposite of power wires. gonna test some other woofers tommorow

[chewie]

is that dc voltage reading normal ?^^^^^^^^^