my freind has a little alpine amplifier and had an older kenwood 10"subwoofer. we had run the power underneath the car to avoid problems with drilling holes in the firewall, so when the inline fuses started to blow i naturally thought that the wire insulation was stripped and was shorting out. he was planning to upgrade anyways so we just reran wire only this time we used 4ga rather than the 10ga that we used last time, also we used some of that hard plastic casing that protects the wires but it made no difference the fuses keep blowing. we tried the amp in another persons vehicle and it worked fine so when we tried using a differenct sub (mtx road thunder) everything woked fine and tehre were no more blown fuses. does anyone know if this really was the sub and how it would cause the fuse to blow?
Replies (17)
UKinstaller on 10/25/2004 20:30:43
sounds like a problem with your wiring. you make the job a lot harder on yourself by running the wires under the car. also, the wire will get mud, dirt, water, and anything else all over it when it is under the car. in a 90 jeep, there is a grommet just to the right of the center of the engine bay, it is in perfect view. use that.
as far as the fuses, go, what are you grounded to, and what size fuse is it that keeps blowing?
-UK
jeepwagonneedsbangin on 10/26/2004 00:14:38
we've grounded it to the floor pan, and there is a 30 amp fuse in the amp so we've been using 20 and 25 amp fuses but they have been blowing non-stop. i know its not the greatest plan but especially now that we have the four gauge wire in there for when he upgrades it made life a lot easier because tryind to hide that big peice of wire when your running it through a vehicle is pain in the neck, also that plastic casing should stop most of the dirt and such from getting all over the wire.
Munchiesyumm on 10/26/2004 00:22:21
Well..
think about what you just said.
The max load pull from the amplifier is 30AMP's however you're putting a 20amp or 25amp fuse on you're power cable next to the battery.
Which means when you crank the volume up the amplifier wants 30amps but you limited the fuse to only let 20-25amp's through. This will defiantly cause it to blow.
Upgrade to a higer rated fuse at LEAST 30amp... at the very least!
UKinstaller on 10/26/2004 00:46:12
stick a 50 amper in there.
-UK
jeepwagonneedsbangin on 10/26/2004 17:12:36
well i understand that but if i was told to put a lower rated amp in the inline fuse so that it is protecting the amp at the same time as well as protecting from shorts and such. also as soon as we put a different sub running off the same amplifier and with the same fuse there haven't been any problems and its been working for about a week.
LC1 on 10/26/2004 18:07:55
You should be using the same rated fuse on the amp inline from your battery power wire. In your case the amp is fused at 30amps, so you should have a 30 amp next to the battery. I wouldn't suggest going with a 50amp as UKinstaller said because this will allow your amp to pull up to 50amps if there was a voltage spike and this would damage your amp (kinda defeats the purpose of a fuse).
As your you amp working with the other sub, what kind of subs are you try to run both the onne that works and doesn't. What are the impedence, Dual 4ohm, Single 4ohm ect. You could be wiring these wrong and puting a lower resistance on the amp causing it to pull to much power.
So before we can give you a better answer we need some more specific details: Model # of amp, and Model # of subs.
-Jay-
PS before anything try puting a 30amp fuse next to the battery, ask most ppl on here and they dont put a smaller fuse next to their battery.
jeepwagonneedsbangin on 10/26/2004 19:35:18
amp- MRV-T505 bridged into a single 10" single 4 ohm voice coil sub. both the road thunder and the kenwood were the same impedance and size with very similar power handling capabilities.
LC1 on 10/26/2004 20:05:04
Well in that case, your best bet would be first to try a 30amp inline fuse. If that doesnt work then I'm sure many ppl here would be happy to help you more.
Jay
UKinstaller on 10/26/2004 20:52:50
i was trained to always use an in-line fuse that is 20 amps above what the amp uses. if the amp can't handle it, it's fuses will blow.
-UK
LC1 on 10/26/2004 21:33:21
Well then I believe that you were improperly trained then. You work at Circuit City am I right? Perfect example of why ppl shouldn't get their gear installed there, they don't even know how to properly train their own employees. Not trying to insult you UK just the big box stores like Circuit City or Best Buy.
Using a bigger fuse, lets say a 50amp inline fuse for an amp that is fused at 30amps, defeats the purpose of using a fuse. A fuse is used to protect your amps etc from harmful high voltage current draw or voltage spikes. Using a larger fuse will allow higher voltages then the amp is designed to handle to reach it. You don't use a bear trap to catch a mouse...it will just walk right through.
I am sure that in most cases using a higher rated inline fuse is fine but why, whats the point, using the proper fuse cost just the same.
Anyways, just my two cents worth,
Jay
PS c'mon someone back me up on this LOL
UKinstaller on 10/26/2004 21:53:40
buddy do you have any idea how many systems i install a week?? and do you have any clue that of those systems, how many people come back saying that their fuses burnt up?? zero. does every single power kit you have have the exact same fuse that comes on the amp you are installing?? nope. it doesn't matter. it's used to protect against ridiculous current sucked up by the wire whether it be by a faulty amp, wiring, whatever. right now i have a 120 amp fuse on an 80 amp system, and absolutely no problems have ever or will ever occur. if i had an 80 amp fuse, my amps would suck more than 80 amps every once in a while and blow the in-line fuse.
oh yeah, check the car stereo cookbook or any other book and it will say the same exact thing. but oh i guess all those guys are wrong too??
and where do you work??
-UK
uochronos on 10/27/2004 03:01:33
actualy inline fuse is more to protect the amp from shorts or large energy spikes if the amp istelf pulls too much current then the onboard fuse well blow... i personaly have always used 10-20amp higehr rated fuse then the onboard fuse. the only time the inline fuse would need to be matched perfectly to the amp is if the amp has no onboard fuse.
i defiantly agree with UK here though. not to say using the exact same fuse well not work but going 10-30amps bigger then the onboard fuse is not going to mess antyhing up.
Inline fuse like i stated above are used incase of a short they well stop the power or incase of a huge energy spike that could damage the amp. the inline fuse is not to protect the amp from drawing too much current.
Chronos
PS
best buy, circuit city, etc they are not the best place and i have had bad experiences but there long term and head installers are usualy quite good. its the rookies, salesman, and prices that get you.
UKinstaller on 10/27/2004 13:11:37
man you guys bash CC, but have i ever given bad advice?? i don't think so, and if i have i admit it and remember it so it doesn't happen again. all i can say is that people like LC1 shouldn't tell me i was trained wrong when he is the one that is wrong. obviously he is the one that needs to be informed of how to install. i can install on anything and everything and am damn good at it, i get few complaints on my installs, and i wouldn't give advice if i didn't think it was right.
-UK
Relax_The_Mind on 10/27/2004 19:24:37
The in line fuse is to to protect your battery/electrical system of the car (unless your amp doesnt have a fuse itself like amps made 10 years ago). You would even be safe putting a 100 amp fuse in there if thats all you had.
The fuse should be as close to/and if possible on your battery terminal. Say you put your "30 amp" fuse on the line and some how the link breaks and the "live" postitive wire is dangling around and makes contact with ground somewhere. BOOM! there goes your battery and probably have to clean up under the hood. The main if not only purpose of an inline fuse is to protect your battery.
Bigger fuses can be more expensive but should always get an inline fuse at with an amp rating of at least ~10% more than the fuse rating of the amp.
So In my "educated" opinion along with what it states right in the amp manuals. You should get a fuse rated at least 35 amps or higher. 50 amp being the most common in your average audio shop.
vicflo
jeepwagonneedsbangin on 10/29/2004 23:00:52
alrite well the fuse hasn't blown for a while, ever since i changed the sub from the kenwood to mtx no fuses have been blown. the kenwood surprisingly sounded better so do you think i should change the fuse then try the kenwood again? also why would the sub cause the fuse to blow even though they are about the same rms power?
ttocs on 10/29/2004 23:08:01
take the sub out of the box and see if the wires are touching?
The inline fuse IS to protect the wire, not the amp... The amp should have a fuse in it, to protect the amp.
I was trained originally at BBY. The training was descent and it got my foot in the door to do so much more. You get a large number of vehicles which is great experience, ya just do not get to do any fun custom stuff.. I to this day REFUSE to buy anything from BBY after they way they treated me as an employee. There are going to be good shops and then not so good at any place you go to. It is all about the installers and if they care. My worst fear was somebody taking a system I installed to another shop and them seeing a hack job with my name on it.....
swez on 10/30/2004 11:08:27
OK fellas, we don't need to bash on each other or companies/equipment etc. That's not the "Mission of this board!!! Yes, we are all entitled to our "opinions"... but let's put this spat to bed.
In a forum of this size, we are bound to have periodic conflicts in opinions and/or personalities. No need to get "snippy" with each other about it either. Show maturity, patience and respect for others as best we can. The "Golden Rule": Treat other as we wish to be treated!!! OK?
Yes, we all have a bad day once in a while... but rise above the petty disputes. "Debates" are fine... "bashing" others is not what we are here for. (end surmon by Pastor Swez)
==================================================
As noted earlier, the inline fuse is there to protect the car electricals. (BAT/ALT and wires) It can be fused up to the current limits of the wire gage and length used. A #4 wire kit is commonly fused between 80-100A., depending on the amps in the install. Again, the inline fuse is there to protect the electricals. Not so much the devices in that circuit. (if you have a #8 line in there, the fuse should be 40-50A.)
Now, back to the issues...
Check out that Kenwood sub carefully! An ohm meter is the proper tool for this test. The nominal reading should be about 3.6 ohms with a DC meter. If you note it to be well under 3.2 ohms, this is the root of the problem. When bridging an amp, 4 ohms (AC impedence) is the normal minimum load a typical bridged amp can handle.
The fact that the fuse blowing stopped when changing to a different sub, indicates the AC impedence of the Kenwood sub may be below normal limits for that amp. That's why testing the sub in box is recommended. It could be wiring issues, a termination cup problem or something about the voice coil on that Kenwood sub, is causing the problem. (a minor shorting of connection wires is enough to create this problem.
Swez
PS Good troubleshooting job on swapping the sub for another. Most would have not considered that option for the conditions noted. (me included)
We (Golds) typically focus on "what" is going wrong and back track to find out the "why". You figured out the "what" of the problem is. (fuse blowing) part of the equation. (sub issue) Now the question to answer is... "why"? Testing (ohmic readings) for that Kenwood sub is the next step. Nice work so far!
Replies (17)
UKinstaller on 10/25/2004 20:30:43
sounds like a problem with your wiring. you make the job a lot harder on yourself by running the wires under the car. also, the wire will get mud, dirt, water, and anything else all over it when it is under the car. in a 90 jeep, there is a grommet just to the right of the center of the engine bay, it is in perfect view. use that.
as far as the fuses, go, what are you grounded to, and what size fuse is it that keeps blowing?
-UK
jeepwagonneedsbangin on 10/26/2004 00:14:38
we've grounded it to the floor pan, and there is a 30 amp fuse in the amp so we've been using 20 and 25 amp fuses but they have been blowing non-stop. i know its not the greatest plan but especially now that we have the four gauge wire in there for when he upgrades it made life a lot easier because tryind to hide that big peice of wire when your running it through a vehicle is pain in the neck, also that plastic casing should stop most of the dirt and such from getting all over the wire.
Munchiesyumm on 10/26/2004 00:22:21
Well..
think about what you just said.
The max load pull from the amplifier is 30AMP's however you're putting a 20amp or 25amp fuse on you're power cable next to the battery.
Which means when you crank the volume up the amplifier wants 30amps but you limited the fuse to only let 20-25amp's through. This will defiantly cause it to blow.
Upgrade to a higer rated fuse at LEAST 30amp... at the very least!
UKinstaller on 10/26/2004 00:46:12
stick a 50 amper in there.
-UK
jeepwagonneedsbangin on 10/26/2004 17:12:36
well i understand that but if i was told to put a lower rated amp in the inline fuse so that it is protecting the amp at the same time as well as protecting from shorts and such. also as soon as we put a different sub running off the same amplifier and with the same fuse there haven't been any problems and its been working for about a week.
LC1 on 10/26/2004 18:07:55
You should be using the same rated fuse on the amp inline from your battery power wire. In your case the amp is fused at 30amps, so you should have a 30 amp next to the battery. I wouldn't suggest going with a 50amp as UKinstaller said because this will allow your amp to pull up to 50amps if there was a voltage spike and this would damage your amp (kinda defeats the purpose of a fuse).
As your you amp working with the other sub, what kind of subs are you try to run both the onne that works and doesn't. What are the impedence, Dual 4ohm, Single 4ohm ect. You could be wiring these wrong and puting a lower resistance on the amp causing it to pull to much power.
So before we can give you a better answer we need some more specific details: Model # of amp, and Model # of subs.
-Jay-
PS before anything try puting a 30amp fuse next to the battery, ask most ppl on here and they dont put a smaller fuse next to their battery.
jeepwagonneedsbangin on 10/26/2004 19:35:18
amp- MRV-T505 bridged into a single 10" single 4 ohm voice coil sub. both the road thunder and the kenwood were the same impedance and size with very similar power handling capabilities.
LC1 on 10/26/2004 20:05:04
Well in that case, your best bet would be first to try a 30amp inline fuse. If that doesnt work then I'm sure many ppl here would be happy to help you more.
Jay
UKinstaller on 10/26/2004 20:52:50
i was trained to always use an in-line fuse that is 20 amps above what the amp uses. if the amp can't handle it, it's fuses will blow.
-UK
LC1 on 10/26/2004 21:33:21
Well then I believe that you were improperly trained then. You work at Circuit City am I right? Perfect example of why ppl shouldn't get their gear installed there, they don't even know how to properly train their own employees. Not trying to insult you UK just the big box stores like Circuit City or Best Buy.
Using a bigger fuse, lets say a 50amp inline fuse for an amp that is fused at 30amps, defeats the purpose of using a fuse. A fuse is used to protect your amps etc from harmful high voltage current draw or voltage spikes. Using a larger fuse will allow higher voltages then the amp is designed to handle to reach it. You don't use a bear trap to catch a mouse...it will just walk right through.
I am sure that in most cases using a higher rated inline fuse is fine but why, whats the point, using the proper fuse cost just the same.
Anyways, just my two cents worth,
Jay
PS c'mon someone back me up on this LOL
UKinstaller on 10/26/2004 21:53:40
buddy do you have any idea how many systems i install a week?? and do you have any clue that of those systems, how many people come back saying that their fuses burnt up?? zero. does every single power kit you have have the exact same fuse that comes on the amp you are installing?? nope. it doesn't matter. it's used to protect against ridiculous current sucked up by the wire whether it be by a faulty amp, wiring, whatever. right now i have a 120 amp fuse on an 80 amp system, and absolutely no problems have ever or will ever occur. if i had an 80 amp fuse, my amps would suck more than 80 amps every once in a while and blow the in-line fuse.
oh yeah, check the car stereo cookbook or any other book and it will say the same exact thing. but oh i guess all those guys are wrong too??
and where do you work??
-UK
uochronos on 10/27/2004 03:01:33
actualy inline fuse is more to protect the amp from shorts or large energy spikes if the amp istelf pulls too much current then the onboard fuse well blow... i personaly have always used 10-20amp higehr rated fuse then the onboard fuse. the only time the inline fuse would need to be matched perfectly to the amp is if the amp has no onboard fuse.
i defiantly agree with UK here though. not to say using the exact same fuse well not work but going 10-30amps bigger then the onboard fuse is not going to mess antyhing up.
Inline fuse like i stated above are used incase of a short they well stop the power or incase of a huge energy spike that could damage the amp. the inline fuse is not to protect the amp from drawing too much current.
Chronos
PS
best buy, circuit city, etc they are not the best place and i have had bad experiences but there long term and head installers are usualy quite good. its the rookies, salesman, and prices that get you.
UKinstaller on 10/27/2004 13:11:37
man you guys bash CC, but have i ever given bad advice?? i don't think so, and if i have i admit it and remember it so it doesn't happen again. all i can say is that people like LC1 shouldn't tell me i was trained wrong when he is the one that is wrong. obviously he is the one that needs to be informed of how to install. i can install on anything and everything and am damn good at it, i get few complaints on my installs, and i wouldn't give advice if i didn't think it was right.
-UK
Relax_The_Mind on 10/27/2004 19:24:37
The in line fuse is to to protect your battery/electrical system of the car (unless your amp doesnt have a fuse itself like amps made 10 years ago). You would even be safe putting a 100 amp fuse in there if thats all you had.
The fuse should be as close to/and if possible on your battery terminal. Say you put your "30 amp" fuse on the line and some how the link breaks and the "live" postitive wire is dangling around and makes contact with ground somewhere. BOOM! there goes your battery and probably have to clean up under the hood. The main if not only purpose of an inline fuse is to protect your battery.
Bigger fuses can be more expensive but should always get an inline fuse at with an amp rating of at least ~10% more than the fuse rating of the amp.
So In my "educated" opinion along with what it states right in the amp manuals. You should get a fuse rated at least 35 amps or higher. 50 amp being the most common in your average audio shop.
vicflo
jeepwagonneedsbangin on 10/29/2004 23:00:52
alrite well the fuse hasn't blown for a while, ever since i changed the sub from the kenwood to mtx no fuses have been blown. the kenwood surprisingly sounded better so do you think i should change the fuse then try the kenwood again? also why would the sub cause the fuse to blow even though they are about the same rms power?
ttocs on 10/29/2004 23:08:01
take the sub out of the box and see if the wires are touching?
The inline fuse IS to protect the wire, not the amp... The amp should have a fuse in it, to protect the amp.
I was trained originally at BBY. The training was descent and it got my foot in the door to do so much more. You get a large number of vehicles which is great experience, ya just do not get to do any fun custom stuff.. I to this day REFUSE to buy anything from BBY after they way they treated me as an employee. There are going to be good shops and then not so good at any place you go to. It is all about the installers and if they care. My worst fear was somebody taking a system I installed to another shop and them seeing a hack job with my name on it.....
swez on 10/30/2004 11:08:27
OK fellas, we don't need to bash on each other or companies/equipment etc. That's not the "Mission of this board!!! Yes, we are all entitled to our "opinions"... but let's put this spat to bed.
In a forum of this size, we are bound to have periodic conflicts in opinions and/or personalities. No need to get "snippy" with each other about it either. Show maturity, patience and respect for others as best we can. The "Golden Rule": Treat other as we wish to be treated!!! OK?
Yes, we all have a bad day once in a while... but rise above the petty disputes. "Debates" are fine... "bashing" others is not what we are here for. (end surmon by Pastor Swez)
==================================================
As noted earlier, the inline fuse is there to protect the car electricals. (BAT/ALT and wires) It can be fused up to the current limits of the wire gage and length used. A #4 wire kit is commonly fused between 80-100A., depending on the amps in the install. Again, the inline fuse is there to protect the electricals. Not so much the devices in that circuit. (if you have a #8 line in there, the fuse should be 40-50A.)
Now, back to the issues...
Check out that Kenwood sub carefully! An ohm meter is the proper tool for this test. The nominal reading should be about 3.6 ohms with a DC meter. If you note it to be well under 3.2 ohms, this is the root of the problem. When bridging an amp, 4 ohms (AC impedence) is the normal minimum load a typical bridged amp can handle.
The fact that the fuse blowing stopped when changing to a different sub, indicates the AC impedence of the Kenwood sub may be below normal limits for that amp. That's why testing the sub in box is recommended. It could be wiring issues, a termination cup problem or something about the voice coil on that Kenwood sub, is causing the problem. (a minor shorting of connection wires is enough to create this problem.
Swez
PS Good troubleshooting job on swapping the sub for another. Most would have not considered that option for the conditions noted. (me included)
We (Golds) typically focus on "what" is going wrong and back track to find out the "why". You figured out the "what" of the problem is. (fuse blowing) part of the equation. (sub issue) Now the question to answer is... "why"? Testing (ohmic readings) for that Kenwood sub is the next step. Nice work so far!
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