Why do my subs get lower when........?

[CJL 10+ year member]

Why do my subs get lower when the engine is off? My flowmasters are kinda loud but i dont think that would be it,i think it has something to do with my RCAs cuz i do have engine noise/alt whine but IDK //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

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[negativezeroz 5,000+ posts]

Have you tried playing sine waves of lik 25Hz with car on and with car off and comparing? So that way you are for sure they aren playing lower...but to me the enclosure would determine that.

Are your RCA's loose?

 

[CJL 10+ year member]

yeah i used test tones(30-25hz) and played Lil wyte's "Hoods run down" with the car off it can hit all the note except for the last one(cuz of my box tuning) but with the car running or driving it can only hit the first note. No my RCAs fit snug.

 

[Trey803 5,000+ posts]

Check your voltage with you car on and off both while playing identical test tones.

 

[snoopdan 5,000+ posts]

your resonant fequency may be near what your flowmaster's resonant tone is...creating cancelation... Its totally possible, I have dual ANSA on my corvette and its low rumble note is at 40 hz at 120 db metered via a Termlab....so its not at all impossible.

 

[CJL 10+ year member]

your resonant fequency may be near what your flowmaster's resonant tone is...creating cancelation... Its totally possible, I have dual ANSA on my corvette and its low rumble note is at 40 hz at 120 db metered via a Termlab....so its not at all impossible.

is there any way to stop that? maybe dynamat?

 

[Blazin_Jason 10+ year member]

v8 with flowmasters> system. For me at least. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[o. l. t. 10+ year member]

It's just your noise floor. Usually becomes a problem when actually moving, but if you have a weak air exchange I could see it happening with just the inherent vibrations of the car being turned on.

Dynamat is not a real solution, but could help change the body's tuning of the metal. Less internal resonance, less cancellation. If it were me, I'd do it because you need sound deadner anyway.

Also, as big as your box is and the fact it is tuned, I'd check to see how much air exchange you actually have going on within the car.

 

[yacob.naif 10+ year member]

same reason your highs get queter when you open your windows while driving

higher noise floor, and the wind cancels out similar frequencies

it's the same way those noise canceling headphones work

your exhaust is just playing the same frequencies as your subs, that's all