PDA

View Full Version : Subs cutting out??


jrcarte78
04-24-2006, 06:36 PM
I feel dumb posting this but here it goes...

I have 2 Pioneer 12s that are powered by a 200w/4ch Pioneer amp that I have bridged to just run the 2 subs. At lower volumes the subs work great and sound awesome. But, when I turn the volume up the speakers cut out. When I turn the volume back down they come back on. Very frustrating. I look at the volt meter while the stereo is on. With the key on but engine not running it's pinned at about 9-11 volts. But while the engine is running it jumps back up above 12. The subs cut out the same whether the motor is running or not. I was hoping somone might have some knowledge to impart on this situation... I'm stumped :confused:

PendO
04-24-2006, 06:38 PM
it's an amp issue ... does your amp have a light to indicate when it goes into protection mode, have someone slowly turn of the volume while you watch the light (if you have one) ... where is the amp that powers the subs getting its sound from? (Direct from the deck or from another amp?)

//// are you trying to run the subs in series (http://www.glenbrook.k12.il.us/gbssci/Phys/Class/circuits/u9l4b.html)?

jrcarte78
04-24-2006, 06:57 PM
it's an amp issue ... does your amp have a light to indicate when it goes into protection mode, have someone slowly turn of the volume while you watch the light (if you have one) ... where is the amp that powers the subs getting its sound from? (Direct from the deck or from another amp?)

//// are you trying to run the subs in series (http://www.glenbrook.k12.il.us/gbssci/Phys/Class/circuits/u9l4b.html)?

There is a light on the amp to indicate its getting power. But, not a light to indicate anything else. The amp remains powered(atleast by the indicator light) even when the subs have cut out. There is only one amp. It gets its sound directly from the deck via a cable with 2 RCA plugs on each end.

Thanks.
:confused:

kalanic
04-24-2006, 07:03 PM
Do you have a capacitor in your power system to your amp?

PendO
04-24-2006, 07:03 PM
I know you said you are bridging the subs from the amp, but are they in series or parallel ... if they are in series that would explain the cut out.

jrcarte78
04-25-2006, 10:14 AM
Do you have a capacitor in your power system to your amp?

No capacitor.... Hoping to get by w/o one.

:o

kalanic
04-25-2006, 10:19 AM
Most of the time your Alt cannot supply enough power to your Battery to keep up with the draw from your amp at higher volumes. i would bet that after you install a capacitor your problems will go away. Try to buy one with a built in Digital read out so you will always know how many volts you have in your system. They are very easy to install.

JimN
04-25-2006, 10:28 AM
The amp is more likely to cut out when the drivers are in parallel, not series. Most amps are designed to work with a 4 ohm load and a higher load presents no problem to them. A lower impedance load will overtax the power supply and make it puke. Bridging an amp and running a 2 ohm load (two 4 ohm speakers in parallel) is effectively a one ohm load. Check the amp's specs- it will show the allowable impedance. Wire them in series and the amp will be much happier.

When an amp can't handle the load (not a bad amp, just not designed for it), there's nothing that a higher alternator or a stiffening cap will do for you.

kalanic
04-25-2006, 10:31 AM
What are your speakers & amp rated for 2 ohm or 4 ohm?

jrcarte78
04-25-2006, 10:32 AM
I know you said you are bridging the subs from the amp, but are they in series or parallel ... if they are in series that would explain the cut out.

I guess they are now wired parallel.

jrcarte78
04-25-2006, 10:37 AM
The amp is more likely to cut out when the drivers are in parallel, not series. Most amps are designed to work with a 4 ohm load and a higher load presents no problem to them. A lower impedance load will overtax the power supply and make it puke. Bridging an amp and running a 2 ohm load (two 4 ohm speakers in parallel) is effectively a one ohm load. Check the amp's specs- it will show the allowable impedance. Wire them in series and the amp will be much happier.

When an amp can't handle the load (not a bad amp, just not designed for it), there's nothing that a higher alternator or a stiffening cap will do for you.

In PendO's post above it sounded like my problem could be if they were wired in series. Your suggestion is to wire them in series. I guess I'm confused....

They are currently wired parallel.

Thanks for all the help gentlemen!!

jrcarte78
04-25-2006, 10:41 AM
What are your speakers & amp rated for 2 ohm or 4 ohm?

This is a very good question and I wish I knew. I no longer have the owner's manuals for either the subs or amp. I have tried to get on Pioneer's web site to get them but they are no longer there. I have also searched the web(by model #s) high and low with no luck. :mad:

Thanks for all the help!

kalanic
04-25-2006, 11:40 AM
Im sure the subs are installed in a box but, on the back of them should state 2 ohm or 4ohm. What is the model number of your amp, I can check some of my resources.

JimN
04-25-2006, 12:03 PM
jcarte- an amp driving a low impedance load will get really hot and the cutting out was probably the thermal protection working. Wiring them in series isn't going to present a difficult load but it won't develop rated output, either.

The output of an amplifier is determined by the power supply voltage and on a 120Vac system, there's plenty of voltage and current available. On a 12Vdc system, the voltage isn't enough to produce a lot of power, especially considering the fact that no circuit is 100% efficient. You can't just increase the voltage going in, you can only try to not lose as much but if the power supply voltage is high enough, you get a lot more output when you compare it with the input.

AC voltage can be increased easily with a transformer but cars and boats work on 12Vdc. The only way to increase the power supply voltage is to create AC and raise it after this stage. Designed right ($$$$), there will be adequate voltage and current capability and the amp will be happy with a low impedance load. Once a price point is a main goal, the cost goes down, along with the ability to drive a low impedance load effortlessly and/or sound quality.

If you have access to a multi-meter, set it to ohms, remove the speaker wires from the sub amp and measure the DC resistance at the wires. If it's above 4 ohms, the woofers are wired in series. If it's below 2 ohms, they're in parallel. Most car woofers are 4 ohm but there are specialty drivers (again, $$$$) that are 2 or 8 ohm.

One more thing- make sure there isn't a lot of insulation stripped off of the wires. One strand of loose wire causing a short will cause some wierd symptoms and yours is one of them.

PendO
04-25-2006, 12:13 PM
I default to whatever JimN says ... he is the man!

http://www.crutchfieldadvisor.com/learningcenter/car/subwoofers_wiring.html?subs=2&impedance=DVC4x2

Check out the above link as it gives differen diagrams at the bottom left of the page

In PendO's post above it sounded like my problem could be if they were wired in series. Your suggestion is to wire them in series. I guess I'm confused....

They are currently wired parallel.

Thanks for all the help gentlemen!!

OhioProstar
04-25-2006, 12:53 PM
Jim,
Could this be an issue of airflow across the amp rather than wiring? I had similar problems until I put 1/2" feet

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=260-773

where the amp mounts to amp board and added a 12volt fan

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=259-132

Also if the wire is not large enough coming from the battery it could cause similar problums.

River Rat
04-25-2006, 01:32 PM
So is it better to run an amp at 4 ohms or 1?

kalanic
04-25-2006, 01:54 PM
So is it better to run an amp at 4 ohms or 1?
IMO, 4 ohms unless you have an amp that can switch. My amp can switch between 4ohms & 2ohms depending on type of speakers. The newer high end speakers are at 2ohms. You get more power from 2ohms. The new Infinity Subs are dual, either 2 or 4ohms.

jrcarte78
04-25-2006, 03:17 PM
I default to whatever JimN says ... he is the man!

http://www.crutchfieldadvisor.com/learningcenter/car/subwoofers_wiring.html?subs=2&impedance=DVC4x2

Check out the above link as it gives differen diagrams at the bottom left of the page

Thanks for the diagram PendO. This one is more like what I've got though. Both speakers have a single voice coil. My question now is: how do I apply this diagram to my set up. It's a four channel amp I want to bridge to 2 channels. But, this looks like it's running off a single channel? Would I run it off of left or right?

Also, thanks for the education JimN--you are the man. :worthy:

Thanks to everyone for all the input.

J.R.

_DiZZ_
04-25-2006, 03:38 PM
I feel dumb posting this but here it goes...

I have 2 Pioneer 12s that are powered by a 200w/4ch Pioneer amp that I have bridged to just run the 2 subs. At lower volumes the subs work great and sound awesome. But, when I turn the volume up the speakers cut out. When I turn the volume back down they come back on. Very frustrating. I look at the volt meter while the stereo is on. With the key on but engine not running it's pinned at about 9-11 volts. But while the engine is running it jumps back up above 12. The subs cut out the same whether the motor is running or not. I was hoping somone might have some knowledge to impart on this situation... I'm stumped :confused:

You have a 4 ch amp.... did you brige the front or rear... Do you have speakers running on any other chan. If you have nothing on the other channel the amp will clip and turn off.

_DiZZ_
04-25-2006, 03:40 PM
Thanks for the diagram PendO. This one is more like what I've got though. Both speakers have a single voice coil. My question now is: how do I apply this diagram to my set up. It's a four channel amp I want to bridge to 2 channels. But, this looks like it's running off a single channel? Would I run it off of left or right?

Also, thanks for the education JimN--you are the man. :worthy:

Thanks to everyone for all the input.

J.R.

A 4 channel amp is Left, Right Front and Left, Right Rear. When you bridge an amp... your using the left and right channel of either front or rear.

kalanic
04-25-2006, 03:43 PM
You have a 4 ch amp.... did you brige the front or rear... Do you have speakers running on any other chan. If you have nothing on the other channel the amp will clip and turn off.
Good Point Dizz! I have had that happen as well.

jrcarte78
04-25-2006, 03:52 PM
I default to whatever JimN says ... he is the man!

http://www.crutchfieldadvisor.com/learningcenter/car/subwoofers_wiring.html?subs=2&impedance=DVC4x2

Check out the above link as it gives differen diagrams at the bottom left of the page

Thanks for the diagram PendO. This one is more like what I've got though. Both speakers have a single voice coil. My question now is: how do I apply this diagram to my set up. It's a four channel amp I want to bridge to 2 channels. But, this looks like it's running off a single channel? Would I run it off of left or right?

Also, thanks for the education JimN--you are the man. :worthy:

Thanks to everyone for all the input.

J.R.

_DiZZ_
04-25-2006, 04:32 PM
http://i19.photobucket.com/albums/b195/i_b_DiZZ_/amp.gif

You should wire your amp something like this. Make sure both front and rear channels are running the same load... Ie 4 ohm.

JimN
04-25-2006, 05:18 PM
Look at that Rockford-Fosgate diagram as one speaker. Your woofers should have come with some kind of instructions and load rating for series or parallel. Some speaker manufacturers don't recommend wiring their dual VC speakers in parallel because of the theoretical effect of not having the same characteristics in each coil, which could cause trouble for some amps. In that case, you wire each speaker's voice coils in series and parallel two woofers on one channel to get the correct load. A,ps are much happier seeing 4 ohms when bridged than 2 ohms.

Ohio- it could be ventilation but I would bet that the amp doesn't like the load it sees.

River Rat- if the amp can handle 1 ohm (very few can and they're $$$$$$), that's fine. The power output of most amps actually drops off with 2 ohms or less. Only a perfect amplifier design will increase the power according to Ohm's Law (P= EČ/R) to the extent that the power doubles when the impedance is halved. More likely, the company understates the output at the more common load and it reflects a dramatic increase at the lower impedance.

jrcarte- When an amp is bridged, it's done on one pair of channels, left and right and depending on the design (and diagram for the amp) you'll use both positives or one + and one -. The left and right channels are normally separated but when the bridging switch is moved, what basically happens is that you are now using two channels in the same direction, increasing the output. However, since both channels are being used, the normal isolation through speaker impedance is decreased by about half and the amp heats up more because it's working harder.

This is a classic case of needing heavier power cable, terminals and ventilation. An amp that is working harder needs every bit of power supply voltage and current it can get. When amps get really hot, there's a situation called 'thermal runaway' where the voltages increase just due to the electronic devices being a bit more efficient as they get hotter. It's like microphone feedback- once it starts, it increases drastically unless something is there to stop or limit it.

This part gets a bit obscure but it'll save someone's speakers and/or amp at some point so I'm going to include it.

If you send a current through a coil that's in a magnetic field, the coil try to move (this is the basis for every electrical motor). If the magnet's polarity is North and the current is causing a North pole field, the coil will try to move away from the magnet. If the coil's polarity is reversed, it'll be attracted to the magnet. If you send an alternating current through the coil, it'll move in and out as the signal's polarity changes. Conversely, if you have a coil in a magnetic field and you move the coil, you will send an electrical current out of the coil (called inducing a voltage) and this becomes a problem when an amplifier starts clipping (distortion caused by trying to exceed the power supply limits) or a speaker cone assembly is particularly heavy. During clipping, the amp also loses the ability to control the speaker's motion. This is a problem because any mass in motion (speaker cone assembly) wants to stay in motion. The speaker's cone and voice coil assembly keeps moving due to the amp not being able to control it and then you have a voltage sent to the amp's output by the speaker's movement. This will shut down just about any amp on the market. The ones that don't shut down will burn up (anyone remember AudioSonic?).

A good way to visualize clipping is to look at a sine wave (and you thought you would never use this after high school, didn't you?) and then draw a straight line across the waves at some point where it's obvious that it's there. The horizontal line segments, while not absolutely flat in practice, are close enough to DC that they cause a lot of heat to build up in the voice coil. This kills speakers. When a voice coil expands from the heat (windings get soft and can stretch, rubbing on the magnet assembly and causing a short), the tube inside (called the former- it forms the coil) can warp and freeze in place. It then becomes a paperweight.

Music is made up of alternating current signals and the amp will reproduce this without distorting until the power supply limits have been reached due to input sensitivity being too high, bass frequencies are increased before getting to the amp, low power supply voltage from skinny wires or bad connections.

bucky
05-25-2006, 02:27 AM
So are you saying his amplifier is too small to power a pair of 12 inch subs?Look at that Rockford-Fosgate diagram as one speaker. Your woofers should have come with some kind of instructions and load rating for series or parallel. Some speaker manufacturers don't recommend wiring their dual VC speakers in parallel because of the theoretical effect of not having the same characteristics in each coil, which could cause trouble for some amps. In that case, you wire each speaker's voice coils in series and parallel two woofers on one channel to get the correct load. A,ps are much happier seeing 4 ohms when bridged than 2 ohms.

Ohio- it could be ventilation but I would bet that the amp doesn't like the load it sees.

River Rat- if the amp can handle 1 ohm (very few can and they're $$$$$$), that's fine. The power output of most amps actually drops off with 2 ohms or less. Only a perfect amplifier design will increase the power according to Ohm's Law (P= EČ/R) to the extent that the power doubles when the impedance is halved. More likely, the company understates the output at the more common load and it reflects a dramatic increase at the lower impedance.

jrcarte- When an amp is bridged, it's done on one pair of channels, left and right and depending on the design (and diagram for the amp) you'll use both positives or one + and one -. The left and right channels are normally separated but when the bridging switch is moved, what basically happens is that you are now using two channels in the same direction, increasing the output. However, since both channels are being used, the normal isolation through speaker impedance is decreased by about half and the amp heats up more because it's working harder.

This is a classic case of needing heavier power cable, terminals and ventilation. An amp that is working harder needs every bit of power supply voltage and current it can get. When amps get really hot, there's a situation called 'thermal runaway' where the voltages increase just due to the electronic devices being a bit more efficient as they get hotter. It's like microphone feedback- once it starts, it increases drastically unless something is there to stop or limit it.

This part gets a bit obscure but it'll save someone's speakers and/or amp at some point so I'm going to include it.

If you send a current through a coil that's in a magnetic field, the coil try to move (this is the basis for every electrical motor). If the magnet's polarity is North and the current is causing a North pole field, the coil will try to move away from the magnet. If the coil's polarity is reversed, it'll be attracted to the magnet. If you send an alternating current through the coil, it'll move in and out as the signal's polarity changes. Conversely, if you have a coil in a magnetic field and you move the coil, you will send an electrical current out of the coil (called inducing a voltage) and this becomes a problem when an amplifier starts clipping (distortion caused by trying to exceed the power supply limits) or a speaker cone assembly is particularly heavy. During clipping, the amp also loses the ability to control the speaker's motion. This is a problem because any mass in motion (speaker cone assembly) wants to stay in motion. The speaker's cone and voice coil assembly keeps moving due to the amp not being able to control it and then you have a voltage sent to the amp's output by the speaker's movement. This will shut down just about any amp on the market. The ones that don't shut down will burn up (anyone remember AudioSonic?).

A good way to visualize clipping is to look at a sine wave (and you thought you would never use this after high school, didn't you?) and then draw a straight line across the waves at some point where it's obvious that it's there. The horizontal line segments, while not absolutely flat in practice, are close enough to DC that they cause a lot of heat to build up in the voice coil. This kills speakers. When a voice coil expands from the heat (windings get soft and can stretch, rubbing on the magnet assembly and causing a short), the tube inside (called the former- it forms the coil) can warp and freeze in place. It then becomes a paperweight.

Music is made up of alternating current signals and the amp will reproduce this without distorting until the power supply limits have been reached due to input sensitivity being too high, bass frequencies are increased before getting to the amp, low power supply voltage from skinny wires or bad connections.