humming from sub
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=32865
Printed Date: May 15, 2024 at 6:04 AM
Topic: humming from sub
Posted By: bp_viper
Subject: humming from sub
Date Posted: May 27, 2004 at 9:47 PM
i have an older lanzar 100-s amp that doesnt have a high low filter, so i have an external crossover. and a 10" sub. the problem is, is i get humming coming from the sub and a some high frequencies, not real high, but words that shouldnt be there. i have the rca's from the head unit connected to the crossover's high input because the low input has speaker terminals for left and right pos and neg, then low pass selected and bass boost off, then rca outs to the amp. and then connected to the sub. what could be causing these sounds out of the sub? is it because the rca's are connected to the high input of the crossover? this is the only thing i can think of right now. if that is what it is, how do i hook up to the low input with the speaker terminals with the sub out rca's from my head unit. thanks
Replies:
Posted By: DYohn
Date Posted: May 27, 2004 at 9:53 PM
Are you hearing high frequency noises or actual high frequency program material (music) through the sub? What is the make/model of the crossover? Usually "high" inputs are for speaker level signals, but it could also just be the way it is labeled. ------------- Support the12volt.com
Posted By: bp_viper
Date Posted: May 27, 2004 at 10:02 PM
its a pyramid gold series cr-66 subwoofer electronic crossover. there are actual words from the music coming through. "high level" could just be better signal u think? since they are rca's, not just speaker terminals. thanks
Posted By: lspker
Date Posted: May 27, 2004 at 10:12 PM
Sounds like you have ground loop problem. The "expensive" lanzar amp has floating ground (I believe) where the pyramid is common ground. Good co have built in switches to change grounds. Try grounding shield of rca.
Posted By: DYohn
Date Posted: May 27, 2004 at 10:18 PM
On that crossover the RCA inputs are the ones to use. Make sure the bass boost is off and the crossover selector set to the middle (80 Hz.) And yes, I agree with the poster above it sounds like a bad ground loop. ------------- Support the12volt.com
Posted By: bp_viper
Date Posted: May 27, 2004 at 10:26 PM
ok, i have read about grounding shield of rca before, but dont remember where, would one of you clear that up for me please? or know of a place to find it. i dont know of a switch that can change grounds either. there is a ground wire that comes out of the amp (thats how old it is, has an actual wire coming out of amp, not just a connector). could the ground be bad all the way up at the deck? thanks guys
Posted By: haemphyst
Date Posted: May 27, 2004 at 11:23 PM
or, and this is the MOST likely answer, the pyramid XO is a POS, and has a VERY shallow 6dB XO slope... this will allow MUCH of the higher frequency stuff through. dump that thing, and get a good piece of gear. the ground issue is a possibility, but that would not cause voices to be heard in the sub, even if it COULD cause noise. what he is describing is a shallow XO slope.
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: bp_viper
Date Posted: May 27, 2004 at 11:27 PM
ok, do you recomend any crossovers that wont cost a lot? amp is old, and if xo is too expensive might as well look into another. thanks
Posted By: haemphyst
Date Posted: May 28, 2004 at 8:30 AM
your definition of " lot" and mine are different, i guarantee it. how much is "a lot"?
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: DYohn
Date Posted: May 28, 2004 at 8:53 AM
One other thing to consider is older amplifiers (and crossovers, EQ, etc) were not built to handle the high output voltages of today's head units. That Lanzar is most likely designed for no more than a 2-volt input. If your head (or that crossover) is sending a higher voltage it will cause high-frequency noise among other things. What's your head unit? Try turning the input gain on the amplifier all the way down and see if the noise stops. ------------- Support the12volt.com
Posted By: bp_viper
Date Posted: May 28, 2004 at 11:43 AM
thats probly true haem. lets just say i am putting together pieces i have laying around to put in my dads truck so the simpler the better as long as it gets the job done. if you know of anything, or a couple, i will look into them. dyohn, my deck is a sony cdx ca810x
Posted By: DYohn
Date Posted: May 28, 2004 at 11:59 AM
OK, that's an older head unit and it has 2-volt pre-outs. So, most likely the Lanzar amp can handle it. Which brings us back to the ground loop issue. Try this for grins: make sure all three pieces 9head unit, crossover, amp) have ground connected directly to the car's chassis. Do not use the factory wiring harness ground for the head unit. See if this helps. If no difference, try directly grounding the outer shield of the RCA cables at the amp. Do this by taking a small wire (18 gage or smaller is fine) and connecting one end to a good ground. Take the other and touch it to the outer part of the RCA connector. You may have to back the cable out a bit to expose the metal outer ring. If this solves the problem, then you can either permanently install your ground jumper, or you could try connecting a wire from teh crossover outer case to the amp outer case, as sometimes this will do the trick. Also, since all three components are, franly, at the VERY LOW end of the quality spectrum, it might simply be that they don't play well together or are simply worn out. Cheers and good luck. ------------- Support the12volt.com
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