keep_hope_alive
Premium Member
Acoustics Engineer
excellent trouble shooting. thank you for the detail.
i'd start by checking for a loose connection in the sub box. also, use your DMM to measure VAC on the amp speaker outputs and see if it's the amp signal dropping out or the subs cutting out (i.e. loose connection).
lights will still dim from 14V to 13V - you may never eliminate headlight dimming completely - unless you're able to completely regulate your car's voltage (or regulate the headlights at 12VDC) Dropping to 13V isn't bad. you're still charging the battery at that point.
i'd start by checking for a loose connection in the sub box. also, use your DMM to measure VAC on the amp speaker outputs and see if it's the amp signal dropping out or the subs cutting out (i.e. loose connection).
lights will still dim from 14V to 13V - you may never eliminate headlight dimming completely - unless you're able to completely regulate your car's voltage (or regulate the headlights at 12VDC) Dropping to 13V isn't bad. you're still charging the battery at that point.
i would change out your wiring for a GOOD 1/0 kit. Something like Knuconceptz, Kicker. I know your amp takes 4 awg so you would need a distro block or reducer.
- Thread Starter
- #4
thanks guys for the quick response, i did measure the outputs from the speakers, and its what i setted it at when i did my gains with my DMM, which is 34 volts.
so any ideas on why the subs stop playin, when i put my volume at 26/35?
so any ideas on why the subs stop playin, when i put my volume at 26/35?
- Thread Starter
- #6
ok i will look in my sub box and see the connections, if you guys can be so nice and direct me to find out how to measure my amp ground with a DMM to see if its faulty, that would be so great thanks
When diagnosing electronic systems for incorrect operation, it is often necessary to verify that ground circuits are good. This article is intended to clarify what is meant by the term "good ground" and the preferred tools and methods for verifying it.
A "good ground" is a ground circuit that has a resistance of zero OHMS.
Ground circuit resistance can be measured in OHMS using a digital volt OHM meter (DVOM). When using a DVOM, it must be set on the 200 OHM scale to obtain an accurate measure of the circuit resistance. Many meters have both a 200 OHM scale and a 200 K scale. The 200 K scale will not measure zero OHMS accurately. If you are not sure how the meter is to be set for the 200 OHM scale, refer to the meter operating instructions for proper settings. If the meter is an autoranging or self-scaling meter, read the meter carefully to be sure which scale it is setting itself to.
Before measuring resistance in any circuit, the resistance of the meter should be measured by touching the leads together. A meter with a good battery and leads in good condition will read less than .2 OHMS usually zero. If the leads measure anything more, an accurate measure of the circuit resistance may not be possible.
Always remember - resistance cannot be measured accurately on a "live" circuit, All current flow through a circuit must be stopped by disconnecting its power source before measuring resistance.
Ground circuit resistance can also be checked by measuring the voltage drop across the circuit with a DVOM set on, the 2 volt scale. The voltage drop will be zero across a "good ground" circuit.
Remember, fully understand a meter's functions before using it!
To add to this, a good ground for car audio applications will have a return resistance reading of 1/2 ohm or less. I have yet to have a return reading of 0 ohms. If a ground return reading cannot be made to get below 1/2 ohm by means of the "BIG 3", then it is adviseable to ground direct to the battery. Electricity is an algebra equation, what you do to one side you must do to the other. Pay as much attention to the ground wire as you do the power wire.
The BIG 3 is a great place to start for a good ground, however it is the assumed proper method of grounding. What we are talking about here is the older and wiser 4th brother to the BIG 3 (the BIG 4).
So a proper ground wire will be as follows.
- clean of residue and paint.
- secure.
- have a resistance return of 1/2 ohm or less.
- be of adequate guage to carry the return as compared to the power wire.
To simplify the measuring of the return, use your meter as described. Disconnect the - battery terminal and disconnect the ground wire from you amp. If your dmm probes are not long enough, you will need to create a jumper extension out of some primary wire or whatever wire you have handy. Measure this wire for any resistance reading and subtract it from the total.
Many installers are not aware of this nor practice this method. It takes time and time = $ so don't get all pissy if you had a professional install done and this was not checked. A poor ground connection or high resistance reading may seem trivial under no load, but once you are pounding your nice new amp and it is drawing large amounts of current, this little reading has become a monster reading that has caused many an amp to fail for no apparent reason. It may be noticeable as a extremely hot running amplifier in a short time period, poor output levels or diminishing levels and of course a blown power supply or output section in the amplifier.
While the original article was written for the years gone by, it still is applicable to the newer generation of vehicles. A good ground is not about the amount or size of the metal in the return to the battery but about the resistance through it. Todays vehicles are a combination of metals, spot welds, glued together unibody panels and isolated chassis components. The return through these components is where the resistance reading comes into question and this is what we need people to understand, why the BIG 4 needs to be done if the BIG 3 does not solve the problem.
Got this material here... http://www.the12volt.com/installbay/forum_posts.asp~TID~49445~PN~1
A "good ground" is a ground circuit that has a resistance of zero OHMS.
Ground circuit resistance can be measured in OHMS using a digital volt OHM meter (DVOM). When using a DVOM, it must be set on the 200 OHM scale to obtain an accurate measure of the circuit resistance. Many meters have both a 200 OHM scale and a 200 K scale. The 200 K scale will not measure zero OHMS accurately. If you are not sure how the meter is to be set for the 200 OHM scale, refer to the meter operating instructions for proper settings. If the meter is an autoranging or self-scaling meter, read the meter carefully to be sure which scale it is setting itself to.
Before measuring resistance in any circuit, the resistance of the meter should be measured by touching the leads together. A meter with a good battery and leads in good condition will read less than .2 OHMS usually zero. If the leads measure anything more, an accurate measure of the circuit resistance may not be possible.
Always remember - resistance cannot be measured accurately on a "live" circuit, All current flow through a circuit must be stopped by disconnecting its power source before measuring resistance.
Ground circuit resistance can also be checked by measuring the voltage drop across the circuit with a DVOM set on, the 2 volt scale. The voltage drop will be zero across a "good ground" circuit.
Remember, fully understand a meter's functions before using it!
To add to this, a good ground for car audio applications will have a return resistance reading of 1/2 ohm or less. I have yet to have a return reading of 0 ohms. If a ground return reading cannot be made to get below 1/2 ohm by means of the "BIG 3", then it is adviseable to ground direct to the battery. Electricity is an algebra equation, what you do to one side you must do to the other. Pay as much attention to the ground wire as you do the power wire.
The BIG 3 is a great place to start for a good ground, however it is the assumed proper method of grounding. What we are talking about here is the older and wiser 4th brother to the BIG 3 (the BIG 4).
So a proper ground wire will be as follows.
- clean of residue and paint.
- secure.
- have a resistance return of 1/2 ohm or less.
- be of adequate guage to carry the return as compared to the power wire.
To simplify the measuring of the return, use your meter as described. Disconnect the - battery terminal and disconnect the ground wire from you amp. If your dmm probes are not long enough, you will need to create a jumper extension out of some primary wire or whatever wire you have handy. Measure this wire for any resistance reading and subtract it from the total.
Many installers are not aware of this nor practice this method. It takes time and time = $ so don't get all pissy if you had a professional install done and this was not checked. A poor ground connection or high resistance reading may seem trivial under no load, but once you are pounding your nice new amp and it is drawing large amounts of current, this little reading has become a monster reading that has caused many an amp to fail for no apparent reason. It may be noticeable as a extremely hot running amplifier in a short time period, poor output levels or diminishing levels and of course a blown power supply or output section in the amplifier.
While the original article was written for the years gone by, it still is applicable to the newer generation of vehicles. A good ground is not about the amount or size of the metal in the return to the battery but about the resistance through it. Todays vehicles are a combination of metals, spot welds, glued together unibody panels and isolated chassis components. The return through these components is where the resistance reading comes into question and this is what we need people to understand, why the BIG 4 needs to be done if the BIG 3 does not solve the problem.
Got this material here... http://www.the12volt.com/installbay/forum_posts.asp~TID~49445~PN~1
- Thread Starter
- #8
great material, thanks for directing me in the right direction, i promise i will spread the knowledge
that article should be stickied. but one thing i dont understand is where do you put the connections for the meter to measure the ground resistance of the chassis? your ground connection area in the trunk and the chassis under the hood?
I might be wrong on this.... so if anyone thinks I am please correct me since I myself am just getting back into car audio.
Chassis ground = Disconnect car battery negative. Place a lead on the negative of the battery, the other on chassis. Should read under .2
Amp ground = Disconnect car battery negative. Place a lead on both ends of the amp negative wire with it removed from the amp. Should read under .2
At least this is how I have checked mine, lol.
Chassis ground = Disconnect car battery negative. Place a lead on the negative of the battery, the other on chassis. Should read under .2
Amp ground = Disconnect car battery negative. Place a lead on both ends of the amp negative wire with it removed from the amp. Should read under .2
At least this is how I have checked mine, lol.
keep_hope_alive
Premium Member
Acoustics Engineer
This is how I measure chassis resistance (off the top of my head):
How to prepare your DMM for measuring very low resistances:
A DMM is limited at it's accuracy for low resistances
The distance from the battery to your amp is usually longer than standard DMM leads can reach. As such, You need a way to extend that wiring. Choose a larger piece of wire - 12AWG is more than sufficient, and solder put alligator clips on each end. In the middle of the wire, cut and solder in a 1/2W 10ohm resistor. Heat shrink and reinforce that connection and now you have a 10 ohm jumper wire.
The reason for the 10 ohm resistor is so your DMM operates within it's desired range. You gain accuracy and can now characterize the resistance of the cabling.
1. Connect DMM leads together, with the 10 jumper, and note the resistance. Label the jumper with this resistance. It won't be 10 ohms exactly due to the tolerance of the resistor and connections.
2. Disconnect Battery Negative and remove oxidation from battery terminal.
3. Disconnect Amp Negative wire/terminal
4. Place DMM leads (with characterized wiring) on each one - ensure good contact to bare metal. Note this resistance.
5. Now take the difference of the two and you have a fairly accurate measurement of a low resistance circuit.
This is a "battery terminal" - not the battery post.
Label this jumper well, you don't want to try using it for anything else.
How to prepare your DMM for measuring very low resistances:
A DMM is limited at it's accuracy for low resistances
The distance from the battery to your amp is usually longer than standard DMM leads can reach. As such, You need a way to extend that wiring. Choose a larger piece of wire - 12AWG is more than sufficient, and solder put alligator clips on each end. In the middle of the wire, cut and solder in a 1/2W 10ohm resistor. Heat shrink and reinforce that connection and now you have a 10 ohm jumper wire.
The reason for the 10 ohm resistor is so your DMM operates within it's desired range. You gain accuracy and can now characterize the resistance of the cabling.
1. Connect DMM leads together, with the 10 jumper, and note the resistance. Label the jumper with this resistance. It won't be 10 ohms exactly due to the tolerance of the resistor and connections.
2. Disconnect Battery Negative and remove oxidation from battery terminal.
3. Disconnect Amp Negative wire/terminal
4. Place DMM leads (with characterized wiring) on each one - ensure good contact to bare metal. Note this resistance.
5. Now take the difference of the two and you have a fairly accurate measurement of a low resistance circuit.
This is a "battery terminal" - not the battery post.
Label this jumper well, you don't want to try using it for anything else.
Last edited by a moderator:
keep_hope_alive
Premium Member
Acoustics Engineer
if you really want to know how much resistance there is from the amp negative terminal connector to the battery negative terminal, you need to know the entire path, including the chassis welds.
don't measure the battery post, just the terminal connector. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif see edits above.
don't measure the battery post, just the terminal connector. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif see edits above.
try this:
Big 3 and power run in 1/0
Big 3 and power run in 1/0
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