Sub Amp not producing enough current... Help

[surferboricua]

This issue has been bugging me for a couple of days. And i've been reading and searching high and low but havent found a definitive answer... Heres my setup and my problem.

My problem is I bought a new 12' Audiopipe subwoofer 4 ohms and rated at 350w RMS, I hooked it up and with my volume all the way up to unclipped levels my bass sounds with low volume. Its not distorted or weak just sound at much lower volume than my mids and highs... The amplifier powering this sub is a BOSS CX2500D monoblock which is rated at 750w RMS at 4 ohms and is going all the way to 29 volts before clipping. I am using oem head unit putting out 6 volts, then a loc which is lowering voltage to 2 volts, then an equalizer putting out 3.4 volts on its subwoofer output and then the sub amplifier.

I set all the gains in my entire system from head unit to subwoofer amplifier using an oscilloscope and got 3.4 volts of input to my subwoofer amplifier. When I raise the volume in my head unit to my determined(unclipped) max volume, the amp is putting out 29 volts but only 1.8 amps(read with a clamp). According to Ohms Law, at the subwoofer impedance of 4 ohms, my amp should be producing at least 7.5 amps of current with 29 volts which would give me 210 watts vs the 52 watts that my subwoofer is currently seeing. I also measured impedance at the speaker and it was reading 3.8 ohms. Its like the amp was seeing an impedance of 16 ohms, but Im only using one subwoofer rated at 4 ohms.

BTW: all my testing was done using a 50hz test tone at 0db.

I dont know what the problem could be and its driving me nuts... Any help would be greatly apprecieated.

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[shauncox26]

I hope im not the first douche to say this but boss is all ****. That amp might push 250 at 1 ohm o would start with new amp

 

[bgowdy 5,000+ posts]

This issue has been bugging me for a couple of days. And i've been reading and searching high and low but havent found a definitive answer... Heres my setup and my problem.
My problem is I bought a new 12' Audiopipe subwoofer 4 ohms and rated at 350w RMS, I hooked it up and with my volume all the way up to unclipped levels my bass sounds with low volume. Its not distorted or weak just sound at much lower volume than my mids and highs... The amplifier powering this sub is a BOSS CX2500D monoblock which is rated at 750w RMS at 4 ohms and is going all the way to 29 volts before clipping. I am using oem head unit putting out 6 volts, then a loc which is lowering voltage to 2 volts, then an equalizer putting out 3.4 volts on its subwoofer output and then the sub amplifier.

I set all the gains in my entire system from head unit to subwoofer amplifier using an oscilloscope and got 3.4 volts of input to my subwoofer amplifier. When I raise the volume in my head unit to my determined(unclipped) max volume, the amp is putting out 29 volts but only 1.8 amps(read with a clamp). According to Ohms Law, at the subwoofer impedance of 4 ohms, my amp should be producing at least 7.5 amps of current with 29 volts which would give me 210 watts vs the 52 watts that my subwoofer is currently seeing. I also measured impedance at the speaker and it was reading 3.8 ohms. Its like the amp was seeing an impedance of 16 ohms, but Im only using one subwoofer rated at 4 ohms.

BTW: all my testing was done using a 50hz test tone at 0db.

I dont know what the problem could be and its driving me nuts... Any help would be greatly apprecieated.

no offense man. but its probly the amp. those are not good amps at at all.

 

[Ahmed Johnson]

I hate to say it, but I doubt you are getting the power you think you are getting

 

[OldManBass]

Pretty much what everybody else says... Boss is junk. Sorry man //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

Is the sub a D2 wired to 4 ohms? If so, maybe wire it down to 2 ohms and see if the amp puts out a little more?

 

[Jeffdachef 5,000+ posts]

i'm pretty sure steve meade amp dyno tested one an amp with the same design and board of a 1200 rms boss amp and he only got 150 rms out of it.

 

[Jeffdachef 5,000+ posts]

also there's too many things your running it through, the signal will be weaker and weaker with all those doohickeys.

 

[bgowdy 5,000+ posts]

Pretty much what everybody else says... Boss is junk. Sorry man //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif
Is the sub a D2 wired to 4 ohms? If so, maybe wire it down to 2 ohms and see if the amp puts out a little more?

you mean 1 ohm

 

[surferboricua]

Lol... thanks all for your answers.

This Subwoofer is SVC, but the one I previously had was a DVC 4ohm wired in parallel to 2 ohm so I was able to pull more out of the amp. I dont know how many watts it was putting out back then because right when I blew that DVC is when I started reading and learned a lot about car audio... BTW when I set all the gains in my equipment with oscilloscope I realized I had been clipping my previous subwoofer the whole time... Poor guy... No wonder...

I was thinking of bypassing that EQ that is right now set to default 0 on all bands and see what happens. Im also wondering about that Line Output Converter taking the signal from 6v (unclipped) to 2 volts. Is this normal?

 

[surferboricua]

What is a good amp I could use for my 12 sub? It is rated 350w rms 4 ohms.

 

[Ahmed Johnson]

Alpine mrp-m500

What is a good amp I could use for my 12 sub? It is rated 350w rms 4 ohms.

 

[JimJ 5,000+ posts]

According to Ohms Law, at the subwoofer impedance of 4 ohms, my amp should be producing at least 7.5 amps of current with 29 volts which would give me 210 watts vs the 52 watts that my subwoofer is currently seeing. I also measured impedance at the speaker and it was reading 3.8 ohms. Its like the amp was seeing an impedance of 16 ohms, but Im only using one subwoofer rated at 4 ohms.

I assume this is a ported enclosure?

The sub likely is seeing an impedance close to what you mention - using the DC resistance of the coil in Ohm's Law isn't accurate if you're playing a test tone anywhere near the impedance peak of the enclosure.

 

[Jeffdachef 5,000+ posts]

Lol... thanks all for your answers.
This Subwoofer is SVC, but the one I previously had was a DVC 4ohm wired in parallel to 2 ohm so I was able to pull more out of the amp. I dont know how many watts it was putting out back then because right when I blew that DVC is when I started reading and learned a lot about car audio... BTW when I set all the gains in my equipment with oscilloscope I realized I had been clipping my previous subwoofer the whole time... Poor guy... No wonder...

I was thinking of bypassing that EQ that is right now set to default 0 on all bands and see what happens. Im also wondering about that Line Output Converter taking the signal from 6v (unclipped) to 2 volts. Is this normal?

The audio signal is going to be weak with lower voltages on the line out, generally you'd want to match the preout from the head unit close to what your amp's signal voltage.

 

[surferboricua]

I assume this is a ported enclosure?
The sub likely is seeing an impedance close to what you mention - using the DC resistance of the coil in Ohm's Law isn't accurate if you're playing a test tone anywhere near the impedance peak of the enclosure.

No, it is not a ported enclosure. Its a closed one...

 

[surferboricua]

The audio signal is going to be weak with lower voltages on the line out, generally you'd want to match the preout from the head unit close to what your amp's signal voltage.

Ive been reading on matching head unit pre amp out to input sensitivity on the amp in order to be able to bring amp to its max output. I forgot to mention the amp has two selections for input sensitivity: from .02V to 2V and from 3V to 8V. My preamp/EQ/line driver has my output to subwoofer at 3.4 volts(unclipped). I was thinking of attenuating the ouput voltage down to close to 2 volts and switch my amps input sensitivity back to .02V to 2V to see what happens.

What do you guys think?

Now on the impedance subject, I was under the impression that if the amp is showing a high enough number of volts on its output then it is a matter of the impedance it sees to determine the total power that it will be putting out. If this is true then I'm worried that I might spend 200$ on an Alpine MRX-M50 and then find myself with the same problem...

BTW.. Thank you guys very very much for all your replies and your help!!!