What Could Be Wrong?

[brooklynjoy2008 10+ year member]

Ok so I checked and your amp is not 1 ohm stable thats your problem. You either need to get a new amp, a new sub that is dual 4 ohm and wire it parallel to 2 ohms, or just wire your sub now in series to 4 ohms.

 

[poisoned10 10+ year member]

Ok so I checked and your amp is not 1 ohm stable thats your problem. You either need to get a new amp, a new sub that is dual 4 ohm and wire it parallel to 2 ohms, or just wire your sub now in series to 4 ohms.

The sub is a dual 4 ohm that is wired to 2 ohms.

 

[sobe3yourself. 10+ year member]

try turning your gains down a bit. i know you said you had the gains set correctly, but they might just be audibly correct. look up how to check the gains with your DMM and do it that way.

 

[poisoned10 10+ year member]

try turning your gains down a bit. i know you said you had the gains set correctly, but they might just be audibly correct. look up how to check the gains with your DMM and do it that way.

I don't know if this is the "correct" way, but I used my DMM and ohm's law to set the gains. I'm wanting 750 watts @ 2ohms which is 1500 and take the square root and that gave me 38.72 and about 45 more numbers. I think the gain is right at 39.0. But that was done with the HU EQ flat and bass boost and LP turned off at the amp.

I'm going to set it again per brooklynjoy2008's method of leaving EQ settings and what not set how I have it and turn the volume to the loudest I listen to it and see what I get.

 

[ahole-ic]

I don't know if this is the "correct" way, but I used my DMM and ohm's law to set the gains. I'm wanting 750 watts @ 2ohms which is 1500 and take the square root and that gave me 38.72 and about 45 more numbers. I think the gain is right at 39.0. But that was done with the HU EQ flat and bass boost and LP turned off at the amp.
I'm going to set it again per brooklynjoy2008's method of leaving EQ settings and what not set how I have it and turn the volume to the loudest I listen to it and see what I get.

Trolling or stupid? Can't tell because aside from the bolded the math was right....

 

[poisoned10 10+ year member]

Trolling or stupid? Can't tell because aside from the bolded the math was right....

I guess just stupid.

If using ohm's law you take the square root of watts*ohms, correct? Or did I misread something?

 

[ahole-ic]

I guess just stupid.
If using ohm's law you take the square root of watts*ohms, correct? Or did I misread something?

lol I thought you meant 1500w instead of doing the gain setting calc. I could not for the life of me understand how you thought 1500w and still got the right voltage for 750w. My fault.

 

[ItsAJeepThing 10+ year member]

If I read correctly he has a JL amp? I thought JL amps were stable from 1.5-4 ohms. So even if his sub is reading a little low it should be ok. Im guessing gains are a little high.

 

[poisoned10 10+ year member]

So I hooked up the DMM with the volume at 25, the highest I listen to music and the EQ set to how i like it and played a 50 hz tone and I got a reading of 60-something. So I moved it down to about 40 and it was just barely above being all the way down. Does that seem normal?

Anyways, I hooked everything back up and a few minutes down the road it cut off again.

 

[IonRL205 10+ year member]

So I hooked up the DMM with the volume at 25, the highest I listen to music and the EQ set to how i like it and played a 50 hz tone and I got a reading of 60-something. So I moved it down to about 40 and it was just barely above being all the way down. Does that seem normal?
Anyways, I hooked everything back up and a few minutes down the road it cut off again.

You're not supposed to set it higher than the number you got from square rooting. Its supposed to be at that number or lower, if you go higher you send a clipped signal and amp can go into protect, so put it back around 38.72, but NOT above it.

Also what are your eq settings set to on your deck? Should be set to flat. Do you have bass boost on your amp? That should be all the way down.

 

[poisoned10 10+ year member]

I did have bass boost on at both the amp and HU. I turned those off and was going to reset my gain but the amp was in protect mode so I couldn't.

I'll do it after work and report back.

 

[poisoned10 10+ year member]

So I did a reset on my gains last night and it still cut out a after a little while.

Did I read correctly that subs will sometimes run at a lower ohm than it is rated during music? If so, maybe it is playing at too low of an ohm load for too long and causing it to go into protect mode?

My amp is only 2 ohm stable and the sub is wired in parallel to 2 ohms. The other day when I did the sub reading it was showing 1.8-1.9 consistantly.

 

[brooklynjoy2008 10+ year member]

No 1.8-1.9 should be fine. If your gain is set at 38.7v then that is not the problem. You should check the voltage at the amp as it shuts off and check the resistance of your ground.

 

[ahole-ic]

Turn your Lowpass filter and bass boost OFF and then set your gain with dmm. Also, are you using rca's or speaker level inputs?

 

[poisoned10 10+ year member]

No 1.8-1.9 should be fine. If your gain is set at 38.7v then that is not the problem. You should check the voltage at the amp as it shuts off and check the resistance of your ground.

Yeah, I know I need to do that but I haven't had a chance to yet. But it is definitely on the agenda for tomorrow.

How do I check the resistance of the ground? And should that be done first? And what should I get as a reading for a good ground?