posted
Lately I have noticed a pronounced low frequency (somewhere near 10 hz would be my guess) modulation coming through my woofer amps when the car is running. With the car off, it immediately stops. This would lead me to believe it has something to do with my alternator. The amps are a pair of MTX TA81001D's strapped in push-pull config. The electrical system is all 1/0 (Including the big three), with 2 Optima group 34 yellow tops. The alternator is a 12V 200 Amp Excessive Amperage unit in the stock honda housing, with an overdrive pulley on it. It modulates the woofers even with the Subsonic Filters on the amps on.
Any Ideas?... Its driving me nuts.
-------------------- "Shut Up And Wheel Your Junk!" Posts: 58 | From: Media, PA | Registered: May 2007
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I went out in the garage to try a few things and I found that the modulation stops anywhere above 1500 RPM. It's only present with the car running from idle to 1500 RPMs.
Hans
-------------------- "Shut Up And Wheel Your Junk!" Posts: 58 | From: Media, PA | Registered: May 2007
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posted
check ur grounds at the amps and headunit. then if still a problem could be ur rca's...
Posts: 6367 | From: north rose,ny | Registered: Aug 2002
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posted
try running a new set of RCA's through the middle of the car, just over the console in the open if possible, or outside the vehicle if a wall. Check all grounds for amps, then battery connections on all ends. If it's still there, try charging each battery individually and testing voltage(and maybe load test) out of circuit. then taking one battery out of the system at a time and listening. these can be done at the same time.
-------------------- World Record-Loudest SPL in my driveway Team Powermaster/XS-Power Hifonics Amps, Kicker subs-The way it should be....all were Stolen from me...boo hoo Zensky....World Domination at It's Finest www.zensky.com Posts: 3763 | From: Columbus, OH - formerly FL | Registered: Oct 2003
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posted
I agree with the RCA recommendation. Low quality or defective RCAs could cause these issues especially when they run along power wires.
Also, have you tried to re-tune your amps? If you are running high voltage in and the gains and bass boost are cranked, then you may get some noise. =Turn down bass boost if this is the case.
-------------------- Ed Lester, Team T3 Audio Team Maxxsonics Team Power Master Team Hooker Audio Team Second Skin Team RazorLite 4 time dB drag World Finalist. 2003, 2005, 2007, 2008 awsome guy at car audio stuff.
Technically astute
4 12" T3 Audio TSS V2s 1 HiFonics XXV Maxximus 8 Power Master D925s
Posts: 1768 | From: near Philly Pa | Registered: Dec 2006
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quote:Originally posted by lmanosteel875: I agree with the RCA recommendation. Low quality or defective RCAs could cause these issues especially [b]when they run along power wires.{/b]
Also, have you tried to re-tune your amps? If you are running high voltage in and the gains and bass boost are cranked, then you may get some noise. =Turn down bass boost if this is the case.
the AC singal running through RCA's is not effected by the DC power running through the power wires.
Posts: 36 | From: blank | Registered: Jun 2007
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posted
[/QUOTE]the AC singal running through RCA's is not effected by the DC power running through the power wires. [/QB][/QUOTE] and where does this theory come from? The DC is creating a large flux which will definitely affect the shape of an alternating current passing through the field...and exponentially increasingly as the AC conductor gets closer to the DC conductor, also increasing based upon the length where the conductor are at a close distance. Electromagnetic basics. If AC and DC didn't interact destructively, standard speakers/subs would not work.
-------------------- World Record-Loudest SPL in my driveway Team Powermaster/XS-Power Hifonics Amps, Kicker subs-The way it should be....all were Stolen from me...boo hoo Zensky....World Domination at It's Finest www.zensky.com Posts: 3763 | From: Columbus, OH - formerly FL | Registered: Oct 2003
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[/QUOTE]the AC singal running through RCA's is not effected by the DC power running through the power wires. [/QB][/QUOTE] and where does this theory come from? The DC is creating a large flux which will definitely affect the shape of an alternating current passing through the field...and exponentially increasingly as the AC conductor gets closer to the DC conductor, also increasing based upon the length where the conductor are at a close distance. Electromagnetic basics. If AC and DC didn't interact destructively, standard speakers/subs would not work.
Thank you, also, with an alternator running, there can be some AC bleed into the DC line
-------------------- Ed Lester, Team T3 Audio Team Maxxsonics Team Power Master Team Hooker Audio Team Second Skin Team RazorLite 4 time dB drag World Finalist. 2003, 2005, 2007, 2008 awsome guy at car audio stuff.
Technically astute
4 12" T3 Audio TSS V2s 1 HiFonics XXV Maxximus 8 Power Master D925s
Posts: 1768 | From: near Philly Pa | Registered: Dec 2006
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posted
Yes, the alternator is running a few cycles of A/C. What's remaining is call "ripple." That's where the phases overlap, but still have peaks and troughs above the average voltage. therefore, you can be clipping and still have peaks in voltage A strong battery helps to filter as well.
-------------------- World Record-Loudest SPL in my driveway Team Powermaster/XS-Power Hifonics Amps, Kicker subs-The way it should be....all were Stolen from me...boo hoo Zensky....World Domination at It's Finest www.zensky.com Posts: 3763 | From: Columbus, OH - formerly FL | Registered: Oct 2003
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posted
What is the best way to detect that "ripple"? It is low and hard to find, does a simple ground help elimanate the a/c ripple into d/c?
Posts: 70 | From: south east GA | Registered: Oct 2007
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posted
try the rca thing. then try doing the Big3 and running a ground wire from the rear ampground to the front bat-.
-------------------- World Record-Loudest SPL in my driveway Team Powermaster/XS-Power Hifonics Amps, Kicker subs-The way it should be....all were Stolen from me...boo hoo Zensky....World Domination at It's Finest www.zensky.com Posts: 3763 | From: Columbus, OH - formerly FL | Registered: Oct 2003
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quote:Originally posted by lmanosteel875: I agree with the RCA recommendation. Low quality or defective RCAs could cause these issues especially [b]when they run along power wires.{/b]
Also, have you tried to re-tune your amps? If you are running high voltage in and the gains and bass boost are cranked, then you may get some noise. =Turn down bass boost if this is the case.
the AC singal running through RCA's is not effected by the DC power running through the power wires.
Explorer is correct. DC CAN NOT couple to another wire at 12V. It can induce a dc charge though but not till your in the kilovolts.
Check your Grounds and try a different ground location.
Posts: 1259 | From: Fullerton. CA ,USA | Registered: Oct 1999
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posted
Actually alternators produce way way way more then 12V. They are not simply rectified like the graphs say. They are rectified up to over 100v and then switched using a PWM voltage regulator down to what ever you set it at. I always added a few diodes in series with the voltage feedback (the small wire off the alternator going to the pos) to kick it up to about 15.5V.
The frequency they operate at is the engine rpm, times the pully ratio which is double or triple?, times the number of poles the alternator has. Im gonna guess a 4-pole motor min. So at 1000 rpm, your ripple frequency (before PWM) is 1000(rpm)*2(pully)*4(poles) = 8 khz. so over the range of rpm say 500 to 5000, your looking at a few khz to out of the audio range. 10hz will never happen.
The problem is a ground loop. I use to have the same problem. It really threw me off cuz the ground where clean and secure. I moved them and problem went away. Ground loops can be tricky!
Posts: 1259 | From: Fullerton. CA ,USA | Registered: Oct 1999
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