DC voltage question

[mumra]

Ok here is d scene, Christmas day i blew my 12 atomic ele approx 2000rms, on boxing day i blew a 15 inch vega 1000rms. The coil in the atomic mash up and unravel, the speaker was redone with an original kit but the person who did it had questionable experience. The vega was only 1000rms but the gains on the amp was dropped also on the crossover. The gains were also about 25% for the atomic.
I mentioned this to a technian he told me to measure the dc voltage across the speaker terminals because a small dc voltage could assist in finishing a good sub.

The amp is a atomic 3000.1 and the dc oltage across the speaker terminals 0.9DC Volts.

Is this voltage enough to Shorten the life of of a woofer? cause i really doh want to Fack up d new sub i buy.

[nervewrecker]

mumra, eh?

btw, best advice I can give you is: give the vega to me!

anyhow, with respct to amp & sub combo, where brain steele? this reinforces my post in another thread.

[mumra]

hard luck dog muh cousin done confascate the sub....

[nervewrecker]

here what to measure:

your output voltage output from you xover or what ever sends the final signal to the amp.

what is your subsonic filter set to on the amp

box tuning frequency (dimensions will be nice, LxWxH, MDF thickness, port area & length)

how long you play for?

was it @ max volume (I mean volume your system maxes out at, not max volume on the headunit)?

& last but not least, a bit about your settings on the head unit (bass boost, eq curve, loud feature) & bass boost on the amp.

[nervewrecker]

The coil in the atomic mash up and unravel

who say bottoming out?

I likes double fudge cookie btw.

[mumra]

ok how yuh does check the output voltage at the crossover, on the rca?
the box was nt built to specs. 17"x15"x30" port area approx. 12" x 2.75"
was not playing music to loud as i was in the car driving and the bassline cap. round 25ish (pioneer 5000 ub)
settings wise i doh realy no cause muh cousin does handle dat, anytime i set the music it does sound like sh!t.
but i do know the bass was never kiking up and the speaker never saw the full power of the amp cause wen we now install d sub we tried to put power on it n it start to smell like it wanna bun down. so i always knew that sub was temporary what i cant figure out y it bun on minimal gain setting. 25%

[mumra]

oh hilo does sell double fudge cookies

[nervewrecker]

what kind of xover is it?

port length?

subsonic filter set to what freq?

[mumra]

clarion cross mcd360
10"
sub sonic filiter off cause it turn rite down

[nervewrecker]

I not gonna check all this tonite, help yourself:

http://www.the12volt.com/caraudio/boxcalcs.asp#rec

check up your box volume (internal) using internal measurements & subtract port volume from it.

get your tuning frequency.

btw, im guessing from the fact that the sub sonic filter right down that could be the fault, lower frequencies below the enclousre tuning frequencies come through to the sub & result in the sub moving like it in free air. mechanical failure IYMC.

Unloading - The tendency of an enclosure to produce no spring or pressure on the woofer. Unloading produces an uncontrollable over-excursion of the woofer cone (it vibrates out of control); the speaker will exhibit low power handling at lower frequencies

http://www.the12volt.com/glossary/gloss ... rms/U.html

.25 of a full turn on the gain might be a tad bit too much btw, try a little less, that xover puts out 5v & the amps gain goes up to 6.

[southside connections]

hmmm another case of poorly set system



somthing seems to be overdriving in the system there

do you have a preamp?, also what volume do you normally play you deck on?


next thing, do you have and other batteries besides the one in the hood?


from what i'm seeing there, dc voltage is usually caused with low current going to ur amp, and also the ele not designed to play that low

re check your system

[mumra]

clarion preamp
normal deck volume 15-20
under hood odessey 1700
in trunk stinger spv 70

[3stagevtec]

The gains were also about 25% for the atomic.

please note that even with the gains set right down, you can still get 100% power from your amp.. so saying your gains is 'only' at 25% means nothing..

i run all my subwoofer amps with gains set to absolute minimum, for both daily use and competition..

[riadb]

ammm....

mumra what is your electrical system like???

[southside connections]

clarion preamp
normal deck volume 15-20

there we go^^

are you aware that there is an "input gain" for the input in the preamp comming from the deck?, you should turn that straight down and set you deck to the highest possible volume increment that does not show distortion

then set the output gains in your preamp, and the input gains to your amp


classic case of overdriving a system

[- Rovin's car audio -]

if "normal deck volume is 15-20 " & its a pioneer deck u have well thats not recommended


i too use minimal gain & have my peak vol around 50\62 ...

[carfreak1024]

^^^^so what about me who uses about half gain on the amps and set the gains correctly on the Audiocontrol EQT to get 5 volts preout and when i crank my music all the way the bass still keeps on going anf getting louder, and wants to go if i had more than volume 62 to go to.

does this mean i have too much headroom on my amps?

i can turn the amps up more but then my mids get drown out and i become i very unhappy person.

also in bassbox pro 6 when using multiple ports and they give you a port length are you supposed to divide that portlength among the 3 ports or make each port that lenght. i know its kinda off topic but this could help me fix some.

[nervewrecker]

^^^^so what about me who uses about half gain on the amps and set the gains correctly on the Audiocontrol EQT to get 5 volts preout and when i crank my music all the way the bass still keeps on going anf getting louder, and wants to go if i had more than volume 62 to go to.

does this mean i have too much headroom on my amps?

i can turn the amps up more but then my mids get drown out and i become i very unhappy person.

also in bassbox pro 6 when using multiple ports and they give you a port length are you supposed to divide that portlength among the 3 ports or make each port that lenght. i know its kinda off topic but this could help me fix some.

what? eh? try speaking english...

when you say half the gain on the amp, what does it go up to? 8? 10v? 12? 110/120v?

what amp is it? what kind of mids you have?

when they give you a port length, you use it. the only thing you divide is the port area.

[noyztoyz]

mumra, what was the resting voltage of the car when idled on full crank when the system was played? I take it you have a voltmeter because months ago i did tell you that was a most important device for any car audio enthusiast.

[mumra]

yea ah install that voltmeter long time

b4 i start d car 12.4

after i start about 13.4

[mumra]

Ok my box wasn't built to specs and my audio system was, is tuned poorly but the question remains about the DC Voltage
These are the voltages across the speaker terminals in my various amps

PPI PC4100. 0.04V
PPI DCX600.4. 0.05V
Atomic 3000.1. 0.9V

Is the dc voltage across the atomic amp enough to damage the sub?
Should I have the amp checked?

[Brian Steele]

also in bassbox pro 6 when using multiple ports and they give you a port length are you supposed to divide that portlength among the 3 ports or make each port that lenght. i know its kinda off topic but this could help me fix some.

You are supposed to use that port length for each port, not divide amongst the ports, otherwise you'll severely mistune the box. Fb, the resonance frequency, will be way too high.

[noyztoyz]

yea ah install that voltmeter long time

b4 i start d car 12.4

after i start about 13.4

good but what were the respective voltages on full crank??

[carfreak1024]

also in bassbox pro 6 when using multiple ports and they give you a port length are you supposed to divide that portlength among the 3 ports or make each port that lenght. i know its kinda off topic but this could help me fix some.

You are supposed to use that port length for each port, not divide amongst the ports, otherwise you'll severely mistune the box. Fb, the resonance frequency, will be way too high.

thanks for the info boi,

i en know what wrong with slacker_jack nah like that man have something in one of his cavities, cuz to me it look like i was speaking english, and i am using CDT CL-62 in front kinda(upgradin to my HD-62 this carnival vacation), and well my rear stage changes plenty. and the gain on the amps is just like 99.99% of all other amps and goes from 6 volts to 0.2 volts, also i en know where yuh ever hear about amp gains goin to 120 volts.

wayz boi a man ask a simple question and you gettin on like somebody do you something.

BTW i using 2 sony XM-2002gtr FOR THE BASS. And an MB Quart DSC4125 for the mids. so 1000rms maybe a little more as i runnin them @3 ohms instead of 4 ohms bridged. They taking this for long so i know they can stand up to it and i guess after box rise and so on they are actually maybe a little higher and maybe at 4 ohms afterall.

hmm but i am feeling like a rell ass now boi, because now i know my box not tuned to 21hz, but more like 33hz, yuh guys think it make sense to tune any lower than this like at my FS which is 29hz. maybe i can get more lows.

[Brian Steele]

Ok my box wasn't built to specs and my audio system was, is tuned poorly but the question remains about the DC Voltage
These are the voltages across the speaker terminals in my various amps

PPI PC4100. 0.04V
PPI DCX600.4. 0.05V
Atomic 3000.1. 0.9V

Is the dc voltage across the atomic amp enough to damage the sub?
Should I have the amp checked?

The one for the Atomic seems a bit high, but even then it shouldn't burn your sub. P=V^2/R. Assuming a 4 ohm load, P=0.9^2/4 = 0.2 Watts. Even if you're running a 1 ohm load, P will still be under a watt - not enough to burn a voice coil. Still, I suggest checking Atomic to see if that DC voltage is within spec.

It could be that one of the output transistors is failing and once the amp warms up it starts sending significant DC voltage through the subwoofer. I've seen that effect once with a car amp - the subwoofer was flailing back and forth at very low frequency.

[carfreak1024]

^^^^one ah my padnas experience this same phenomenon in his car as well and it caused the sub to burn. he was playing it for like 6 hours at a new year's lime, car is a diesel, system fully cranked, then it tripped once or twice and he put it back on and the third time it trip, the bass did not come on and we know what went on then.

[Brian Steele]

hmm but i am feeling like a rell ass now boi, because now i know my box not tuned to 21hz, but more like 33hz, yuh guys think it make sense to tune any lower than this like at my FS which is 29hz. maybe i can get more lows.

LOL. I think you should be fine at that tuning. It will improve the power handling of your subwoofers within the passband (basically Fb to the x-over frequency you're using for your subs). A lower tuning *may* extend your passband, at the expense of power-handling within the passband. Easy to check the effect - simply block up one or more of the vents, so to see if you prefer the results at lower Fb.

BTW, you can check Fb very easily if you have access to a resistor (1 to 4 ohms preferable), a multimeter and a tone source connected to your amp (a CD with tracks representing recorded tones from 20 Hz to 100 Hz played through your HU could do. I use my laptop with the freeware NCH tone generator, or use the one built-in to the TrueRTA software). Simply connect the resistor in series with your box, play the various tones at low level, and measure the voltage across the resistor while you're do so. For a vented box, Fb will be where the voltage measured across the resistor peaks (max current flow). For a sealed box, Fb will be where the voltage measured across the resistor is at it lowest (minimum current flow). I suggest checking it if possible, as in many cases it might not be that predicted by the box software programs due to several reasons (proximity of the vent to the sides of the enclosure, for example).

[carfreak1024]

^^^^is using a 4ohm speaker the same as a resistor and if not where can i buy one. and what is the usual cost.

[Brian Steele]

^^^^is using a 4ohm speaker the same as a resistor and if not where can i buy one. and what is the usual cost.

No, it's not the same.

If you've got an old x-over handy, you may be able to find one in the tweeter section. Otherwise check the nearest electronics repair shop.

[carfreak1024]

so any 4 ohm resistor will work huh, no particular values and will this one still work as my sub is a 3 ohm sub.