Hello all. I have a jbl 75.2 (297 wats) amp and i am running a infinity sub which pumps (300wats)( 1200 peak). The problem i am having is the amp keeps cutting out. it will work for a few secounds or half hour and the cut out and then restart and so on. i have checked the connection and the all seem to be fine. i have even replaced the phono connection. i have connected the auto on lead to the head units illumination wire do you think that is the problem? i have a 1999 vw polo. Please helppp!
Replies (14)
Victor on 05/16/2006 11:14:20
Looks like the amp is over heating and going into protection mode,
There can be 2 issues here,
1 : Incorrect impedance: what is the model number of the sub..? is it a DVC ? what is the impedance of each voice coil and how have you wired them to the sub? that JBL is a 2 channel class AB amp. in stereo mode it can take impedances as low as 2 ohms, and in bridged mode it can take impedances only as low as 4 ohms. If you ahve wired them in bridged mode for a 2 ohm load then this is bound to happen, check it out.
2: Gain settings: This is another issue which needs to be checked, Ideally the gains should be set at the RCA out voltage of the head unit, What HU do u have and what are the specs or the RCA outs. If they are 2 volt outs then the gains on the amp should be set at 2 ohms, if its a 4volt pre-out then the gains should be set at 4 volts. If you have set the gains that do not match this then there are possibllities for clipping and over heating and the amp going into protection mode. Check this out too..(Gain settings are NOT Volume settings on the amp, its a different fundamental in itself, so donot treat it as a volume knob)
Hope this helps.
Victor...
dips on 05/16/2006 12:10:44
ok il try your suggestions and let yu know. o and the head unit is Kenwood KDCW-4031. where do you reccomend putting the rca if not the illumination wire
dips on 05/16/2006 12:30:30
the head unit is kenwood 4031 iv lost the maual so dont know the specs there is a remote control wire but using that would mean i have to cut the wire and sleeve it and then connect the rca wire and the using electrical tape to seal it would you recommend doing that? also it cant be overheating as even if i trythe amp the next day its sill on protect mode.
ttocs on 05/16/2006 12:37:09
"the head unit is kenwood 4031 iv lost the maual so dont know the specs there is a remote control wire but using that would mean i have to cut the wire and sleeve it and then connect the rca wire and the using electrical tape to seal it would you recommend doing that?"-----No, as I do not understand what you mean....
What is the gain on the amp set at? It shouldn't be more then 2/3-3/4 max power.
dips on 05/16/2006 12:43:55
the gain on the amp is set at 2/3 a little less and the wire i am talking about is labeled "remote control"
Victor on 05/16/2006 12:50:50
where do you reccomend putting the rca if not the illumination wire...??? RCA into the illumination wire?? i guess u are confused...
dips on 05/16/2006 15:34:42
im sorry ignore the last reply i gave it was stupid i am using normal speaker cables to run the sub. i had brought the whole lot together and that was the cables which as supplied i have just looked at mymates car and his speaker cable from amp to sub is much thicker so i will be down the shops tommrow getting the much fatter speaker cable. do you think that will solve my problem? also i am using a 20amp fuse on the power cable which is running from the battery is that ok?
ttocs on 05/16/2006 18:09:48
what size is the fuse on the amp? Using that number decides what size power wire you use, and the size of the power wire will determin the size of the fuse on the power wire. The fuse in the amp protects the amp. The fuse on the wire next to the battery is to protect the pwr wire.
swez on 05/17/2006 04:42:13
Which infinity sub model is used here?
Swez
Victor on 05/17/2006 05:31:32
DONT OVER LOOK THIS REPLY... they seems to be the one of the most obvious reasons for your amp cutting out...
Double check the following and give us your feedback.
Looks like the amp is over heating and going into protection mode,
There can be 2 issues here,
1 : Incorrect impedance: what is the model number of the sub..? is it a DVC ? what is the impedance of each voice coil and how have you wired them to the sub? that JBL is a 2 channel class AB amp. in stereo mode it can take impedances as low as 2 ohms, and in bridged mode it can take impedances only as low as 4 ohms. If you ahve wired them in bridged mode for a 2 ohm load then this is bound to happen, check it out.
2: Gain settings: This is another issue which needs to be checked, Ideally the gains should be set at the RCA out voltage of the head unit, What HU do u have and what are the specs or the RCA outs. If they are 2 volt outs then the gains on the amp should be set at 2 ohms, if its a 4volt pre-out then the gains should be set at 4 volts. If you have set the gains that do not match this then there are possibllities for clipping and over heating and the amp going into protection mode. Check this out too..(Gain settings are NOT Volume settings on the amp, its a different fundamental in itself, so donot treat it as a volume knob)
Hope this helps.
Victor...
dips on 05/17/2006 10:26:36
the sub is a infinty refrence sub 1240w 4ohms with a 51mm voice coil diameter. i have changed the speaker set up and taken it out of bridged mode and it seems to be working. i also changed the gain settings. i will post back as soon as it goes again which i think it will. i will also change the speaker cable to a subwoofer cable at the moment it is a normal speaker cable the thin wire that was supplied with the package.
swez on 05/17/2006 11:08:34
Victor is giving the key things to check. For this power range, 12 gage wire is adequte.
This is a 4 ohm SVC sub. (1 voice coil) Therefore, you can bridge this amp into MONO mode and get the most from it.
Your gain setting is what is causing the amp to shut off. Set your gain control between 2-4 volts. If the amp shuts off, raise the gain a bit.
NOTE: If your amp gain is set below 2.0 volts, the amp will reach full power too soon and cause the amp to over heat and shut off to cool. Especially at high bass volumes.
Swez
Victor on 05/17/2006 11:32:08
That HU has the Pre-out voltage rated at 2.0 volts,
set the Hu gains between 2.5 to 2.0 and your amp should be safe and well performing...
do not go below 2.0 volts, this will cause your amp to over heat and cut out..
Victor..
P.S. : as swez said, that infinity sub u got is a 4 ohm SVC and it would be safe to run it in bridged mode, so you can go ahead and bridge the amp again to get more power. As noted it looks like the real problem lies with the gain settings.
Post a feedback if everything goes ok.. saying "THANKS"
....hehehehehehe... GRIN
well dont worry, we are all here to help and be helped. thats what CK is all about..if you still have problems let us know we will have to put our brains together and take a closer look.
but dont worry since u are here your problem will be solved in the most logical and technical manner.
dips on 05/17/2006 11:48:31
ok i will try but its raining at the moment herein london so i will have to try later lol o and by the way can i take this opputunity to thank every1 who has replied and helped sort out my problem thank again!
Replies (14)
Victor on 05/16/2006 11:14:20
Looks like the amp is over heating and going into protection mode,
There can be 2 issues here,
1 : Incorrect impedance: what is the model number of the sub..? is it a DVC ? what is the impedance of each voice coil and how have you wired them to the sub? that JBL is a 2 channel class AB amp. in stereo mode it can take impedances as low as 2 ohms, and in bridged mode it can take impedances only as low as 4 ohms. If you ahve wired them in bridged mode for a 2 ohm load then this is bound to happen, check it out.
2: Gain settings: This is another issue which needs to be checked, Ideally the gains should be set at the RCA out voltage of the head unit, What HU do u have and what are the specs or the RCA outs. If they are 2 volt outs then the gains on the amp should be set at 2 ohms, if its a 4volt pre-out then the gains should be set at 4 volts. If you have set the gains that do not match this then there are possibllities for clipping and over heating and the amp going into protection mode. Check this out too..(Gain settings are NOT Volume settings on the amp, its a different fundamental in itself, so donot treat it as a volume knob)
Hope this helps.
Victor...
dips on 05/16/2006 12:10:44
ok il try your suggestions and let yu know. o and the head unit is Kenwood KDCW-4031. where do you reccomend putting the rca if not the illumination wire
dips on 05/16/2006 12:30:30
the head unit is kenwood 4031 iv lost the maual so dont know the specs there is a remote control wire but using that would mean i have to cut the wire and sleeve it and then connect the rca wire and the using electrical tape to seal it would you recommend doing that? also it cant be overheating as even if i trythe amp the next day its sill on protect mode.
ttocs on 05/16/2006 12:37:09
"the head unit is kenwood 4031 iv lost the maual so dont know the specs there is a remote control wire but using that would mean i have to cut the wire and sleeve it and then connect the rca wire and the using electrical tape to seal it would you recommend doing that?"-----No, as I do not understand what you mean....
What is the gain on the amp set at? It shouldn't be more then 2/3-3/4 max power.
dips on 05/16/2006 12:43:55
the gain on the amp is set at 2/3 a little less and the wire i am talking about is labeled "remote control"
Victor on 05/16/2006 12:50:50
where do you reccomend putting the rca if not the illumination wire...??? RCA into the illumination wire?? i guess u are confused...
dips on 05/16/2006 15:34:42
im sorry ignore the last reply i gave it was stupid i am using normal speaker cables to run the sub. i had brought the whole lot together and that was the cables which as supplied i have just looked at mymates car and his speaker cable from amp to sub is much thicker so i will be down the shops tommrow getting the much fatter speaker cable. do you think that will solve my problem? also i am using a 20amp fuse on the power cable which is running from the battery is that ok?
ttocs on 05/16/2006 18:09:48
what size is the fuse on the amp? Using that number decides what size power wire you use, and the size of the power wire will determin the size of the fuse on the power wire. The fuse in the amp protects the amp. The fuse on the wire next to the battery is to protect the pwr wire.
swez on 05/17/2006 04:42:13
Which infinity sub model is used here?
Swez
Victor on 05/17/2006 05:31:32
DONT OVER LOOK THIS REPLY... they seems to be the one of the most obvious reasons for your amp cutting out...
Double check the following and give us your feedback.
Looks like the amp is over heating and going into protection mode,
There can be 2 issues here,
1 : Incorrect impedance: what is the model number of the sub..? is it a DVC ? what is the impedance of each voice coil and how have you wired them to the sub? that JBL is a 2 channel class AB amp. in stereo mode it can take impedances as low as 2 ohms, and in bridged mode it can take impedances only as low as 4 ohms. If you ahve wired them in bridged mode for a 2 ohm load then this is bound to happen, check it out.
2: Gain settings: This is another issue which needs to be checked, Ideally the gains should be set at the RCA out voltage of the head unit, What HU do u have and what are the specs or the RCA outs. If they are 2 volt outs then the gains on the amp should be set at 2 ohms, if its a 4volt pre-out then the gains should be set at 4 volts. If you have set the gains that do not match this then there are possibllities for clipping and over heating and the amp going into protection mode. Check this out too..(Gain settings are NOT Volume settings on the amp, its a different fundamental in itself, so donot treat it as a volume knob)
Hope this helps.
Victor...
dips on 05/17/2006 10:26:36
the sub is a infinty refrence sub 1240w 4ohms with a 51mm voice coil diameter. i have changed the speaker set up and taken it out of bridged mode and it seems to be working. i also changed the gain settings. i will post back as soon as it goes again which i think it will. i will also change the speaker cable to a subwoofer cable at the moment it is a normal speaker cable the thin wire that was supplied with the package.
swez on 05/17/2006 11:08:34
Victor is giving the key things to check. For this power range, 12 gage wire is adequte.
This is a 4 ohm SVC sub. (1 voice coil) Therefore, you can bridge this amp into MONO mode and get the most from it.
Your gain setting is what is causing the amp to shut off. Set your gain control between 2-4 volts. If the amp shuts off, raise the gain a bit.
NOTE: If your amp gain is set below 2.0 volts, the amp will reach full power too soon and cause the amp to over heat and shut off to cool. Especially at high bass volumes.
Swez
Victor on 05/17/2006 11:32:08
That HU has the Pre-out voltage rated at 2.0 volts,
set the Hu gains between 2.5 to 2.0 and your amp should be safe and well performing...
do not go below 2.0 volts, this will cause your amp to over heat and cut out..
Victor..
P.S. : as swez said, that infinity sub u got is a 4 ohm SVC and it would be safe to run it in bridged mode, so you can go ahead and bridge the amp again to get more power. As noted it looks like the real problem lies with the gain settings.
Post a feedback if everything goes ok.. saying "THANKS"
....hehehehehehe... GRIN
well dont worry, we are all here to help and be helped. thats what CK is all about..if you still have problems let us know we will have to put our brains together and take a closer look.
but dont worry since u are here your problem will be solved in the most logical and technical manner.
dips on 05/17/2006 11:48:31
ok i will try but its raining at the moment herein london so i will have to try later lol o and by the way can i take this opputunity to thank every1 who has replied and helped sort out my problem thank again!
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