Crackling Rears

[zjsager1]

Hey all,
This is in reference to my other thread about me setup here: https://www.caraudio.com/threads/seeking-advice-on-my-sq-audio-build.616391/

When dialing in gain for the sub with 40hz, I noticed very noticeable crackling coming from the rear speakers (RF T1650) at high volume. I assumed it was because I was pushing them too hard, but this doesn't make sense since they amp can only do 50 RMS and the speakers are rated for 75 RMS. I checked out the amp, but no clip light was on. So I unplugged all the other speakers' low level signal RCAs except for the rears to isolate the issue, in which something strange was happening.

When ONLY the rear left speaker was connected and playing, the rear right speaker was crackling? Yet the rear left speaker sounded clean. When ONLY the rear right speaker was connected and playing, the rear left speaker was crackling. With BOTH connected and playing, both crackle and play the 40 hz. I have my crossover at the Kicker Key amp at 80 hz.

Do I have a bad amp? It only happens when the amp is pushing 75% of it's power before clipping. Thanks.

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[CarAudio.com - Hal AI Bots]

Hey all,
This is in reference to my other thread about me setup here: https://www.caraudio.com/threads/seeking-advice-on-my-sq-audio-build.616391/

When dialing in gain for the sub with 40hz, I noticed very noticeable crackling coming from the rear speakers (RF T1650) at high volume. I assumed it was because I was pushing them too hard, but this doesn't make sense since they amp can only do 50 RMS and the speakers are rated for 75 RMS. I checked out the amp, but no clip light was on. So I unplugged all the other speakers' low level signal RCAs except for the rears to isolate the issue, in which something strange was happening.

When ONLY the rear left speaker was connected and playing, the rear right speaker was crackling? Yet the rear left speaker sounded clean. When ONLY the rear right speaker was connected and playing, the rear left speaker was crackling. With BOTH connected and playing, both crackle and play the 40 hz. I have my crossover at the Kicker Key amp at 80 hz.

Do I have a bad amp? It only happens when the amp is pushing 75% of it's power before clipping. Thanks.

It sounds like you're experiencing a challenging audio issue. I recommend checking the connections and possibly testing with another amp or speaker to isolate the problem.

 

[Doxquzme Premium Member]

Could the HU be the source?

Get one of these (if for no other reason, it's great to test things with),

https://www.amazon.com/dp/B0FC6K3GNR/?tag=caraudiocom-20

Plug it into your phone or laptop and see if, after doing the same test, you still get rattling,

When testing, use 1 RCA for the channel/speaker you're testing.

If, after doing these things, you still have noises emanating from the speakers in any fashion. Undo all the connections, clean it up using a microscope to make sure something isn't hanging around on the power/ground/remote or the RCA/Hi-level inputs (if applicable). And for the last thing, make sure that the RCA inputs are not shorting or lose, giggle them a bit, see if anything changes.

After that, yeah, I'd say it's internal to the amp.

This could be tested by disconnecting all the speakers too, connecting one of the speaker terminal leads to a bookshelf speaker or anything really, listen for the noise. If it's the amp, it should show up on another speaker too.

 

[RobGMN Premium Member]

Maybe I'm misreading, but are you trying to play a 40Hz tone out of 6.5" speakers with a 50 watt amp?

I think those speakers have something like a 15dB drop at the 50hz point (i.e. - a 6.5" speaker is not really made for reproducing 40Hz in a proper box, much less a car door).

You mention the 80 Hz crossover, but then crackling at 40Hz, so I'm thinking the 40 is not a goal.
Did you run the auto-setup on the Key with the sub disabled? I wonder if it set the crossover point lower than the 80Hz you say it is set for (spitballing here).

 

[ThxOne Premium Member]

That is odd. I am wondering why you have rear speaker wire colors going in to the LC7i into the Main Input and front color speaker wires going in to Channel 2? Can't the LC7i sum just the main input to all 3 RCA outputs? If so, I would disconnect the speaker wires you have going into the input of Channel 2 on the LC7i and see if it fixes the crackling. There may be some crosstalk in the LOC. Also, try the white and grey wires into the main input and see if they alone will eliminate the crackling. I am not sure how you have that 9 wire connected or to what to get signal but typically on most installs the white and grey are front left and right and the green and purple wires are the left and right rear.

What I am suggesting is just simplifying the signal input into the LC7i and see if it helps. Here is some info from Audio Control that may clear all this up. Try to hook the wiring up like the picture provided as it appears to sum everything and allow for all three outputs. This is from Audio Controls site.

https://audiocontrolmobile.zendesk.com/hc/en-us/articles/22048880425869-Channel-summing-Signal-routing-with-line-converters-LC6i-LC7i-LCQ-1

 

[Jimi77 Premium Member]

 

[RobGMN Premium Member]

Is there a 40Hz test tone in there somwhere?