Bass Response

[bigwheel82]

I've got a new Galaxy 929, with a new Wilson 1000 mag. mounted up in my Grand Cherokee. Been noticing on and off that when I'm listening to my stereo sometimes I get a warbled beat from my 929 swinging to the tune on my stereo. Now, I've also got a pair of 12" subs in the cargo area with an amp<150-300W> mounted under the back seat with all wiring run under the carpet through the center console and up to the stereo. All power wires for the stereo amp, CB were routed in the exact same path direct to the battery. For lack of space, I mounted my CB on the right side of the console, ran the antenna wire all the way to the back of the Jeep and came out of a hole I drilled behind the taillight up to the roof. Curious to know what's going on. I've checked the ground to the amp<under the seat aswell> but not sure if it needs to be moved or what.<?> Maybe I might need to rethink the path of the power wires to the batt?

 

[W5LZ]

Sounds like your stereo is 'getting into' the radio. There are various ways of keeping the stereo out of the radio, trying them shouldn't hurt. That ranges from separating the wiring as much as possible, to several tons of ferrite 'beads'/cores. You might try grounding the radio chassis if you haven't, that helps sometimes.
Good luck.
- 'Doc

 

[VA3ES]

One of two things is happening:

1) Your stereo's bass is actually modulating your radios PLL causing a warble.. This is common. Just turn down the bass, or the volume!

2) Your stereo is drawing so much current that it's dropping the battery voltage at an audio rate, again, modulating your PLL. Same fix as above, or, get a second batterey, or beef up your alternator.

 

[bigwheel82]

Yeah when I turn "off" the subs it immediately goes away. Never noticed it before because I wouldn't turn on the stereo. I can't say for sure, but the alternator in my rig could be original, though I don't know, but a 17 yr old vehicle with a stock alt? Oh well, something to look into. Also, I had a buddy of mine pull right up beside me, and not realizing the severity of the issue, he was talking on his cb and it was lighting up my SWR light. I've read that you can overload the "front" of the radio. Does this sound like it could be an effect of that?

 

[hotrod]

One of two things is happening:

1) Your stereo's bass is actually modulating your radios PLL causing a warble.. This is common. Just turn down the bass, or the volume!

2) Your stereo is drawing so much current that it's dropping the battery voltage at an audio rate, again, modulating your PLL. Same fix as above, or, get a second batterey, or beef up your alternator.

i agree with this.it is possible to still have the orignal alt. even if it was replaced
usually most people replace it with the same size

 

[radiohobby]

Your radio is feeling the effects of the alternator trying to power that amp. If there is room inside the radio you might try putting a 1000mfd electrolytic cap in there accross the power lead and then that cap can supply the juice when is drops down from the source just like it would in a power supply.

 

[unit_399]

try putting a 1000mfd electrolytic cap in there accross the power lead and then that cap can supply the juice when is drops down from the source just like it would in a power supply.

Radio hobby has the right idea, but you need to go it one better. First, go to your local car stereo dealer and get a one farad capacitor. Install it across the power leads of your stereo amp as close to the amp as possible. Then get a 10,000 uf/16vdc capacitor (or larger) and install it across the power leads of the Galaxy. This will help keep the supply voltage in your vehicle from dropping excessively when the bass in your stereo is really pumping, and should keep the audio out of your cb. 73s

- 399

 

[dudmuck]

Several tons of ferrite beads?? is this an RFI problem?

Probably the best thing to do is borrow an oscilloscope, and use it to measure directly on the battery as your big audio amp is running. Observe any audio riding on the DC.
Then after that, do the same measurement on the DC connector to your CB.
Is the audio riding on the DC coming right off the battery, or is it being coupled by the DC feed wires? thats the question to answer.

In any case, its best to make sure your big audio amp is not drawing current thru the chassis of your vehicle. It should be drawing current only thru its DC feed wires. Running large currents thru vehicle chassis causes ground loop.