Ok I had what I thought was a amp problem , now I know it is something else. Here is the long story in short form , read amp shutting down for better details. I installed a new deck ,speakers ,amp and subwoofers in a 1991 Nissan Hardbody pickup and it worked great. Then he wanted some subs that were better looking so he bought some new sony 4 ohm subs I installed the subs into a old kenwood box that had the orignial tweeters and a xover. After the new subs were installed every thing sounded good but after about 10 min or so the amp cut out , started the truck and lowered the vol on the HU and kicked right back on and ran great. He drove off and about a day or so later , he tells me the amp shutdown but never came on , I figured that the amp was fried and told him to comeover and I would look and see if I could find the prob. When he gets to my house the amp was on and running fine as well as the subs. The next day he tells me that the amp shut down a hour after he left my house , so I told him to take the amp back and get a new one. He did and when I installed the amp the same problem arose the protection light came on. So my question is what is my problem with this system I thought it might be the preamp outs but it that was the case the amp would not have came back on and worked for awile. The amp has power so it cant be the power wire and the ground is a good place with bare metal on it. The amp comes on and goes off with the deck so the remote wire is fine. The subs????? if it was the subs wouldn't they just sound bad and why would they work all of a sudden and go bad again? the only thing other than that I can come up with is the Xover on the tweeters but still why would it work and then not work. Ideas any one????FROWN
Replies (16)
Swez on 08/3/2003 10:28:51
What amp is he using and how did you wire the subs to same?
If this is a 2 channel amp, and you bridged it MONO, it will only take a 4 ohm load (min.) If you wired both subs in parallel to this amp, have a 2 ohm load and the amp will not cope well with that low of resistance w/o overheating and shutting down to cool.
There are generally thermal protect circuits in most newer amps to monitor heat build up within the amp. If that thermal limit is reached, the amp shuts off to protect itself.
The best you can do here, is use it as a 2 channel amp and run 1 sub per channel OR... rewire the subs to series configureation for an 8 ohm load. This will cut the power to speakers by 3 dB/sub, but the amp will not shut off this way.
The other option is to use a MONO amnp that can take 2 ohm loads. But that means taking back this amp and shopping for a new one.
Finally, how many watts RMS are the subs rated for and what gage power and ground wire are used for the main amp power feeds. (main Pos and ground gage?)
Swez
baine on 08/3/2003 10:53:16
Ok he is useing a 400 watt 4 channel amp bridged so that would be 200 watts per sub. each sub has its own bridged channel . The set up worked find before like this. The subs are a 4ohm 600 watt peak so I guess about 300 rms( just a guess ) but this is a new amp and It did not make any sound but the protection light is on. The wire is 8 gage on both ground and power. The power has a inline fuse next to the batt and is run through the firewall , then under the carpet. the ground is the same gauge and is on a seat mount bolt. At first I thought the preouts on the HU might have fried but after I thought about it , there really is not any way they could have came in contact to the power wire or any source of power. So I am thinking the Xover in the box might have been for a 8 ohm load and fried. any ideas?
baine on 08/3/2003 11:16:36
Also is it safe to run the amp like this it dose say bridgable ?
compvr15s on 08/3/2003 12:52:22
have you tried to just run one sub, on one channel and leave the other off. also is there a buttin or a switch to flip to go from 4ch to 2ch. how long is your ground cable? and does it have a good connection. i used to have a 4 channel mtx amp that would do the same thing in my car. so i took it out and didnt use it for about a year and i sold it to a buddy and he has not had a problem with it, so im thinking maybe it was the ground. does the amp overheat at all. i know 10 mins isnt very long but it would only take about 15 for my mtx to shut off. have you tried to bypass the cross over? is it on the inside of the box, if so pull the sub out and just disconnect it from the terminal. im not sure if it would lower the ohm load or not but im sure it probably would, and if its 8ohms then the original subs were prolly 8 ohm too givin it 4ohms so it would run find. but since the new subs are 4ohm this might be a problem, but dont take my word for it good luck!
Relax_The_Mind on 08/3/2003 15:58:25
Baine,
So...if im guessing right you connected the tweeters also in that old kenwood box. Id say not to use the crossover or tweeter. If you are sending full range tot he subs I dont suggest it. Those subs wont be designed with that specific crossover and tweet combo.
Most of the time a protection light comes on is from overheating due to poor impedance matching. If you can tell me exactly how you wired the subs +/- to the amp. It would help a lot more (we can help you a lot more) if we can get exact model numbers of the amp and speakers. Maybe even the HU.
RTM
baine on 08/3/2003 16:57:45
I figured it out after pulling out the deck , putting a new one in and the putting the old deck back in. It was the stupid fuse by the battery was not all the way in. I pushed it in and bingo had it . started the car and the fuse poped out again. Yes it is the fuse it came with so I used a zip tie to keep it in the holder and works fine. Have to cut the zip tie every time the fuse goes but I never have had to replace one yet. That was the big problem I still do not get why the amp had power nuff to go into protect mode and not nuff to run .... who cares it works GRIN
Swez on 08/4/2003 06:48:10
Very interesting diagnostics here as the problems mentioned mimic an amp being driven by too low an ohms load. "Classic symptoms to a tee".
The scenario of bridging a 4 channel down to a 2 channels and running a 4 ohm sub off each new channel is generally fine and should work well under most conditions. The only thing I could add is that if the gains are set to very low sensitivity, the amp will try to reproduce as large a signal as it can, based on input voltage from the HU. If the amp is driven too hard and has inadequate cooling, it will get hot and go into thermal protection mode. (even if the ohms load is correct)
Fuse slipping out of the holder huh? That's a rare condition. Wonder if the fuse holder is either defective as it does not have sufficient clip strength to hold the fuse fixed. Am wondering if this amp is drawing so much current through this fuse holder, that it too heats up, the clips expand with heat and release the fuse? That's a real stretch... but if you think about it... this is possible in the summer heat. We all know that metals expand with heat right? I dunno...
Finally, mentioned he is using #8 gage power and ground wire here right? What is the fuse rating on this amp... 2 x 20A, 3 x 15A or other? A quality #8 wire can handle ~50A. of current under normal conditions. But it also depends on the length of wire used and termination hardware quality.
What brand and series is this amp anyway???
Swez
baine on 08/4/2003 20:20:56
Ok the amp is a walmart special :Virtual Reality Sound Labs 4-Channel Car Amp VRA4.0 heres the link to it :http://www.walmart.com/catalog/product.gsp?product_id=2168515&cat=39008&type=19&dept=3944&path=0%3A3944%3A3947%3A39008. It has 2/20Amp fuses and the wire was only run in to the back of the cab.
Yea it was something I my self have never ran into. It still didn't make any sence as it had power to go in to protect mode but thats it . I checked the deck the speakers and the amp and they all worked (took me hours of installing and removal as I do not have a test bench;-( ) All that was left was wiring. I told the guy to take it to video Kingdom and have them figure it out. One last time I went through the wiring and just happed to bump the fuse while the deck was on and it kicked in . He started the truck and it was off , I went and pushed the fuse down and there it was . I went and got a zip tie and It has not even gotten warm sence. THERE IS A LESSON TO BE LEARNED HERE , ALWAYS CHECK YOUR WIRING AND FUSES FIRST. I Started messing with his truck at 11:30 AM at about 85 degrees finished at 4:30 pm at 103 Degrees . If I would have checked it first I would have been there 20 min most. And all I got out of it was 30 bucks for the inital install and thats it , but I love this kind of stuff I wish I did it for a living GRIN
baine on 08/4/2003 20:34:41
Now he wants to put in a new amp for the subs and use that amp for all the speakers in the factory holes.... Unfourtunatly he only has one set of preamp outs on the deck .. I will need to get a adapter for the back of the deck so I can use RCA jacks as the amp dose not have High inputs. Does any one know if the local install shop will have them or is that something that is kind of rare if it is my shop will not have it . I live in nebraska and we never have anything .
Swez on 08/4/2003 20:42:06
That's not a bad plan... get a good sub amp and use the 4 channel for interior speakers.
He'll need to upgrade the power wire and fuse to accomodate the new sub amp and 4 channel as well.
As for the wiring of signal lines, there are "Y" cables and patch cords that you can find at Radio Shack or even Walmart that have a single female and dual male RCA jacks. These can be added to the HU and additional RCA wires ran for the new sub amp/
There is a better way... but a better HU would solve many of these issues or just use the rear speaker wires to feed the input section if the new sub amp. Can use the high signal inputs or add a Line out convertor to rear speakers that feed RCA signals to sub amp.
Easy deal!
Swez
PS See if you can make a few extra $'s for your 2nd go at this upgrade. Shops charge a lot more for these services and probably won't do a better job than you can... as you lear the ropes. The biggest issue... you care about your install work.... many install jockies don't so much.
baine on 08/4/2003 21:00:35
I have him interested in my CD deck that is in my car . It has 2 pre outs front and rear it is a sony Xplode deck I like it but I am not sure that he will want to pay 100 bucks for it . It is worth it I payed 250 2 years ago . I still have the box and manuals . I was looking for a CD deck I can afford and the one I came up with was a Blaupunkt San Jose , I like it as I am wanting to upgrade my system with one n 4 channel amp and a 2 channel for my subs. and it has 3 sets of preamps and it sees to be in my price range. Does any one have any thing to say about the: Blaupunkt San Jose good or bad???
The guy says he will give my a total of like 50 bucks..... a installer would have charged him like 200-250 mabey more for all the time I put in . I want to start doing this out of my house but I am not too sure how to get customers and if it is a good Idea as a freaking fuse threw me for a loop , thanks for all of your input guys as it was not helpful but did give me knowledge and that is more valueable (cant spell ) sometimes more than help. I will stay on here and post to the forum with anything I can help with... witch (spelling again) may not be any help at alll GRIN
ttocs on 08/4/2003 21:45:04
I have done limited work out of my house, and I don't like doing it. I have worked for 6 yrs on and off as a professional installer(3.5 yrs fulltime). I considered doing it for cash out of the garage, but I would have to say it is a bad idea for most people, including me. there is so much liability in doing even a deck install. It does not take much to mees up and cause a costly repair. Even a great installer can make a simple mistake and end up owing more then the install was worth. Everyone does it with enough time....
As fer blaupunkt, I have owned one in the past, and could probably own one now. They slipped for a long time but from what I understand they are making a comeback.. I would rate them as good or better then sony....
baine on 08/4/2003 23:06:06
ok thanks i will stick to freinds and family i figured that could come up
Tray on 08/5/2003 17:00:21
Exactly what scott said. The liability is huge.
That and if you have a good system, and any equipment around, who knows what sort of people may decide they need it more than you. Happened to me in high school, but luckily I cought the guy trying to sell my stuff.
I won't go into details about the confrontation, as this is a family rated site.
Box making is another story, as you don't physically get into the wiring, so if you really want to do something, I'd suggest maybe starting there.
baine on 08/5/2003 17:36:02
Well I do not think that I will do it on the side as it is costly if you mess up. I normaly will not even look at something that someone else has installed as most of the people around here are too cheap to buy a harness that will use the factory wiring. It is really hard to mess up too much with a wiring harness . But if you break the dash or something esle it would be nice to have a company paying for it instead of you.
As for box building I am not good at it . I want to learn but dont have the right tools to do it . You need more than a jigsaw thats all I have. I tried to build one with a jigsaw it was ugly and way too big for 12s would have been great for 18s though.... lol
Swez on 08/5/2003 20:24:04
Wise choice and good advice from others. I agree, the liability of making a seemingly minor oversite, could cost you plenty in damages to a clients car electricals, dash panels, doors etc.
If you learn a bit more in time, you may want to consider only doing very simple installs like amps, subs and maybe speaker upgrades on vehicles you know well.
Can always ask the client/friend to sign a waiver that does not hold you liable... but I would not accept those terms from an installer either.
In short, just read, learn and understand this is not rocket science, but things can and do go wrong.... just look at what is posted day in and day out on the board right???
Swez
Replies (16)
Swez on 08/3/2003 10:28:51
What amp is he using and how did you wire the subs to same?
If this is a 2 channel amp, and you bridged it MONO, it will only take a 4 ohm load (min.) If you wired both subs in parallel to this amp, have a 2 ohm load and the amp will not cope well with that low of resistance w/o overheating and shutting down to cool.
There are generally thermal protect circuits in most newer amps to monitor heat build up within the amp. If that thermal limit is reached, the amp shuts off to protect itself.
The best you can do here, is use it as a 2 channel amp and run 1 sub per channel OR... rewire the subs to series configureation for an 8 ohm load. This will cut the power to speakers by 3 dB/sub, but the amp will not shut off this way.
The other option is to use a MONO amnp that can take 2 ohm loads. But that means taking back this amp and shopping for a new one.
Finally, how many watts RMS are the subs rated for and what gage power and ground wire are used for the main amp power feeds. (main Pos and ground gage?)
Swez
baine on 08/3/2003 10:53:16
Ok he is useing a 400 watt 4 channel amp bridged so that would be 200 watts per sub. each sub has its own bridged channel . The set up worked find before like this. The subs are a 4ohm 600 watt peak so I guess about 300 rms( just a guess ) but this is a new amp and It did not make any sound but the protection light is on. The wire is 8 gage on both ground and power. The power has a inline fuse next to the batt and is run through the firewall , then under the carpet. the ground is the same gauge and is on a seat mount bolt. At first I thought the preouts on the HU might have fried but after I thought about it , there really is not any way they could have came in contact to the power wire or any source of power. So I am thinking the Xover in the box might have been for a 8 ohm load and fried. any ideas?
baine on 08/3/2003 11:16:36
Also is it safe to run the amp like this it dose say bridgable ?
compvr15s on 08/3/2003 12:52:22
have you tried to just run one sub, on one channel and leave the other off. also is there a buttin or a switch to flip to go from 4ch to 2ch. how long is your ground cable? and does it have a good connection. i used to have a 4 channel mtx amp that would do the same thing in my car. so i took it out and didnt use it for about a year and i sold it to a buddy and he has not had a problem with it, so im thinking maybe it was the ground. does the amp overheat at all. i know 10 mins isnt very long but it would only take about 15 for my mtx to shut off. have you tried to bypass the cross over? is it on the inside of the box, if so pull the sub out and just disconnect it from the terminal. im not sure if it would lower the ohm load or not but im sure it probably would, and if its 8ohms then the original subs were prolly 8 ohm too givin it 4ohms so it would run find. but since the new subs are 4ohm this might be a problem, but dont take my word for it good luck!
Relax_The_Mind on 08/3/2003 15:58:25
Baine,
So...if im guessing right you connected the tweeters also in that old kenwood box. Id say not to use the crossover or tweeter. If you are sending full range tot he subs I dont suggest it. Those subs wont be designed with that specific crossover and tweet combo.
Most of the time a protection light comes on is from overheating due to poor impedance matching. If you can tell me exactly how you wired the subs +/- to the amp. It would help a lot more (we can help you a lot more) if we can get exact model numbers of the amp and speakers. Maybe even the HU.
RTM
baine on 08/3/2003 16:57:45
I figured it out after pulling out the deck , putting a new one in and the putting the old deck back in. It was the stupid fuse by the battery was not all the way in. I pushed it in and bingo had it . started the car and the fuse poped out again. Yes it is the fuse it came with so I used a zip tie to keep it in the holder and works fine. Have to cut the zip tie every time the fuse goes but I never have had to replace one yet. That was the big problem I still do not get why the amp had power nuff to go into protect mode and not nuff to run .... who cares it works GRIN
Swez on 08/4/2003 06:48:10
Very interesting diagnostics here as the problems mentioned mimic an amp being driven by too low an ohms load. "Classic symptoms to a tee".
The scenario of bridging a 4 channel down to a 2 channels and running a 4 ohm sub off each new channel is generally fine and should work well under most conditions. The only thing I could add is that if the gains are set to very low sensitivity, the amp will try to reproduce as large a signal as it can, based on input voltage from the HU. If the amp is driven too hard and has inadequate cooling, it will get hot and go into thermal protection mode. (even if the ohms load is correct)
Fuse slipping out of the holder huh? That's a rare condition. Wonder if the fuse holder is either defective as it does not have sufficient clip strength to hold the fuse fixed. Am wondering if this amp is drawing so much current through this fuse holder, that it too heats up, the clips expand with heat and release the fuse? That's a real stretch... but if you think about it... this is possible in the summer heat. We all know that metals expand with heat right? I dunno...
Finally, mentioned he is using #8 gage power and ground wire here right? What is the fuse rating on this amp... 2 x 20A, 3 x 15A or other? A quality #8 wire can handle ~50A. of current under normal conditions. But it also depends on the length of wire used and termination hardware quality.
What brand and series is this amp anyway???
Swez
baine on 08/4/2003 20:20:56
Ok the amp is a walmart special :Virtual Reality Sound Labs 4-Channel Car Amp VRA4.0 heres the link to it :http://www.walmart.com/catalog/product.gsp?product_id=2168515&cat=39008&type=19&dept=3944&path=0%3A3944%3A3947%3A39008. It has 2/20Amp fuses and the wire was only run in to the back of the cab.
Yea it was something I my self have never ran into. It still didn't make any sence as it had power to go in to protect mode but thats it . I checked the deck the speakers and the amp and they all worked (took me hours of installing and removal as I do not have a test bench;-( ) All that was left was wiring. I told the guy to take it to video Kingdom and have them figure it out. One last time I went through the wiring and just happed to bump the fuse while the deck was on and it kicked in . He started the truck and it was off , I went and pushed the fuse down and there it was . I went and got a zip tie and It has not even gotten warm sence. THERE IS A LESSON TO BE LEARNED HERE , ALWAYS CHECK YOUR WIRING AND FUSES FIRST. I Started messing with his truck at 11:30 AM at about 85 degrees finished at 4:30 pm at 103 Degrees . If I would have checked it first I would have been there 20 min most. And all I got out of it was 30 bucks for the inital install and thats it , but I love this kind of stuff I wish I did it for a living GRIN
baine on 08/4/2003 20:34:41
Now he wants to put in a new amp for the subs and use that amp for all the speakers in the factory holes.... Unfourtunatly he only has one set of preamp outs on the deck .. I will need to get a adapter for the back of the deck so I can use RCA jacks as the amp dose not have High inputs. Does any one know if the local install shop will have them or is that something that is kind of rare if it is my shop will not have it . I live in nebraska and we never have anything .
Swez on 08/4/2003 20:42:06
That's not a bad plan... get a good sub amp and use the 4 channel for interior speakers.
He'll need to upgrade the power wire and fuse to accomodate the new sub amp and 4 channel as well.
As for the wiring of signal lines, there are "Y" cables and patch cords that you can find at Radio Shack or even Walmart that have a single female and dual male RCA jacks. These can be added to the HU and additional RCA wires ran for the new sub amp/
There is a better way... but a better HU would solve many of these issues or just use the rear speaker wires to feed the input section if the new sub amp. Can use the high signal inputs or add a Line out convertor to rear speakers that feed RCA signals to sub amp.
Easy deal!
Swez
PS See if you can make a few extra $'s for your 2nd go at this upgrade. Shops charge a lot more for these services and probably won't do a better job than you can... as you lear the ropes. The biggest issue... you care about your install work.... many install jockies don't so much.
baine on 08/4/2003 21:00:35
I have him interested in my CD deck that is in my car . It has 2 pre outs front and rear it is a sony Xplode deck I like it but I am not sure that he will want to pay 100 bucks for it . It is worth it I payed 250 2 years ago . I still have the box and manuals . I was looking for a CD deck I can afford and the one I came up with was a Blaupunkt San Jose , I like it as I am wanting to upgrade my system with one n 4 channel amp and a 2 channel for my subs. and it has 3 sets of preamps and it sees to be in my price range. Does any one have any thing to say about the: Blaupunkt San Jose good or bad???
The guy says he will give my a total of like 50 bucks..... a installer would have charged him like 200-250 mabey more for all the time I put in . I want to start doing this out of my house but I am not too sure how to get customers and if it is a good Idea as a freaking fuse threw me for a loop , thanks for all of your input guys as it was not helpful but did give me knowledge and that is more valueable (cant spell ) sometimes more than help. I will stay on here and post to the forum with anything I can help with... witch (spelling again) may not be any help at alll GRIN
ttocs on 08/4/2003 21:45:04
I have done limited work out of my house, and I don't like doing it. I have worked for 6 yrs on and off as a professional installer(3.5 yrs fulltime). I considered doing it for cash out of the garage, but I would have to say it is a bad idea for most people, including me. there is so much liability in doing even a deck install. It does not take much to mees up and cause a costly repair. Even a great installer can make a simple mistake and end up owing more then the install was worth. Everyone does it with enough time....
As fer blaupunkt, I have owned one in the past, and could probably own one now. They slipped for a long time but from what I understand they are making a comeback.. I would rate them as good or better then sony....
baine on 08/4/2003 23:06:06
ok thanks i will stick to freinds and family i figured that could come up
Tray on 08/5/2003 17:00:21
Exactly what scott said. The liability is huge.
That and if you have a good system, and any equipment around, who knows what sort of people may decide they need it more than you. Happened to me in high school, but luckily I cought the guy trying to sell my stuff.
I won't go into details about the confrontation, as this is a family rated site.
Box making is another story, as you don't physically get into the wiring, so if you really want to do something, I'd suggest maybe starting there.
baine on 08/5/2003 17:36:02
Well I do not think that I will do it on the side as it is costly if you mess up. I normaly will not even look at something that someone else has installed as most of the people around here are too cheap to buy a harness that will use the factory wiring. It is really hard to mess up too much with a wiring harness . But if you break the dash or something esle it would be nice to have a company paying for it instead of you.
As for box building I am not good at it . I want to learn but dont have the right tools to do it . You need more than a jigsaw thats all I have. I tried to build one with a jigsaw it was ugly and way too big for 12s would have been great for 18s though.... lol
Swez on 08/5/2003 20:24:04
Wise choice and good advice from others. I agree, the liability of making a seemingly minor oversite, could cost you plenty in damages to a clients car electricals, dash panels, doors etc.
If you learn a bit more in time, you may want to consider only doing very simple installs like amps, subs and maybe speaker upgrades on vehicles you know well.
Can always ask the client/friend to sign a waiver that does not hold you liable... but I would not accept those terms from an installer either.
In short, just read, learn and understand this is not rocket science, but things can and do go wrong.... just look at what is posted day in and day out on the board right???
Swez
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