gmoneyjive Posted August 7 Report Share Posted August 7 dunno if this really applies to this forum, but here goes..I just got a rockford power 851x 4 channel amp, and after it's been running for 20 mins or so, the base cuts out (2 rear channels). It seems to cut out at top volume, then as I cut the volume down to 2/3 or so it comes back in... and inbetween it's there, but not full power. It's wired the way it should be (4 ohm bridged), and I've checked a few other causes I've had trouble with in past systems, such as a loose ground causing the amp to cut out & loose power seemingly at random. This is just weird because it works fine when cold (for the first 20 mins), and the front 2 channels (mids & highs) are not affected, only the rear 2. And the amp doesn't shut off completely like it's getting too hot, it only just attenuates the base, varying on the volume level (attenuates more, almost completely at high volume).Any ideas on what might cause this, or other places to get help? Or is the amp just faulty? Quote Link to comment Share on other sites More sharing options...
joeg Posted August 8 Report Share Posted August 8 good question... definately applies to this forum...and to answer it:you're amp is overheating... i had this problem with an old rockford 250.a2 a while back... i believe they have a saftey mechanism thats shuts them off at a certain temperature, and turns them back on when it cools off...mine was mounted in the hatch of my eclipse... no ventilation back there... what i did was, i went to radioshack, picked up huge cooling fan... used some heat-resistant epoxy from homedepot and mounted it right over the fins... those fans are 12v dc, so you can just wire it in with the amp... never had a problem again.if you can remount the amp somewhere with better ventilation, try that... otherwise give the fan solution a try...before you do anything... check all your wiring. Quote Link to comment Share on other sites More sharing options...
joeg Posted August 8 Report Share Posted August 8 i just reread what you said... i was under the impression your front channels were on another amp like mine were...so you're saying 2 of the 4 channels cut out?what are the gain settings on each channel? Quote Link to comment Share on other sites More sharing options...
Guest brwneydtrouble Posted August 8 Report Share Posted August 8 You might have a bad speaker somewhere, the distortion causing the amp to clip. That and the fact that you have a cheap amp. Try using Pheonix Gold or two seperate amps. Quote Link to comment Share on other sites More sharing options...
joeg Posted August 8 Report Share Posted August 8 Originally posted by brwneydtrouble You might have a bad speaker somewhere, the distortion causing the amp to clip. That and the fact that you have a cheap amp. Try using Pheonix Gold or two seperate amps. since when is rockford cheap? Quote Link to comment Share on other sites More sharing options...
Guest brwneydtrouble Posted August 8 Report Share Posted August 8 When its not right for the setup? Quote Link to comment Share on other sites More sharing options...
joeg Posted August 8 Report Share Posted August 8 Originally posted by brwneydtrouble When its not right for the setup? that doesn't make any sense...and this is DEFINATLEY not a cheap amp....110 watts RMS x 4 at 4 ohms 215 watts RMS x 4 at 2 ohms 425 watts RMS x 2 in bridged mode at 4 ohms 2-, 3-, or 4-channel output 4-ohm stable in bridged mode Tri-Way capable requires 4-gauge power and ground leads and a 60-amp fuse — wiring and hardware not included with amplifier 2 questions i have:1) are you using 4gauge or beter wiring?2) what are the ratings of the speakers you have this hooked up to... 110 RMS is a lot of power for small drivers... and not enough power for subs... what ohm load are you working with? Quote Link to comment Share on other sites More sharing options...
joeg Posted August 8 Report Share Posted August 8 Quote Link to comment Share on other sites More sharing options...
gmoneyjive Posted August 8 Author Report Share Posted August 8 Originally posted by brwneydtrouble You might have a bad speaker somewhere, the distortion causing the amp to clip. That and the fact that you have a cheap amp. Try using Pheonix Gold or two seperate amps. I'd like to know what kinda crack u smoke.Joe - yeah, 2 of the 4 channels cut out (partially, not all the way - which is what I find very weird), and come back in gradually as I step the volume down... it's not just an on-off issue.On my old setup I had a rockford 600a4, running components front & back, and it was under a shelf that only gave it a half inch of clearance - and to my surprise that never cut out... I had a power 1000a2 under the same condition, and being pushed to the max I think it only cut out once on a 10 hour drive in 95 degree heat in like 2 years... so anyway my opinion of rockford power amps became pretty high. Before that, I had a USAcoustics amp (shitty back then, dunno how they are now), and that cut out all the time. But again, that was a cut & dry thing... it cut out for a few mins, then came back on once the temp dropped.You may have a point on the gain settings... I know I set the gain on the rear 2 channels quite a bit higher, as it only pushes around 490 watts rms 4 ohm bridged, and the sub is a power hx2 12" (1000 watts rms)... so naturally I wanted to get teh most out of it for the buck. I woulda done it the right way and got a big amp for teh subs and a 4 channel for the components (like I had last summer, before some fucker stole it all )... but I'm saving up for a supra if I can ever find one Anyway, I'm just surprised it doesn't cut out completely, then come back on like I've seen many amps do. I'm also surprised that a rockford power amp is doing this at all, given the hell I put my old ones thru and they always performed great. It's got plenty of room for ventilation, but as u mentioned a fan would help. I'll try turning the gain down tomorrow & goin for a ride, see how it works... thanks for the help. Quote Link to comment Share on other sites More sharing options...
gmoneyjive Posted August 8 Author Report Share Posted August 8 Originally posted by joeg that doesn't make any sense...and this is DEFINATLEY not a cheap amp....110 watts RMS x 4 at 4 ohms 215 watts RMS x 4 at 2 ohms 425 watts RMS x 2 in bridged mode at 4 ohms 2-, 3-, or 4-channel output 4-ohm stable in bridged mode Tri-Way capable requires 4-gauge power and ground leads and a 60-amp fuse — wiring and hardware not included with amplifier 2 questions i have:1) are you using 4gauge or beter wiring?2) what are the ratings of the speakers you have this hooked up to... 110 RMS is a lot of power for small drivers... and not enough power for subs... what ohm load are you working with? I'm using 4 gauge, should be plenty for the load. The componenets are all rockford fanatic q, 100 watts rms apiece... the front 2 channels are wired with both front & back components cuz I only wanted to go with 1 amp, thus a 2 ohm stereo load... the amp is capable of a lot more than 200 watts rms, thus I have the gain turned down in the front.. The 2 rear channels are bridged into a 4 ohm load (1 power hx2 with the dual voice coils wired in series)... and the manual says that's fine Quote Link to comment Share on other sites More sharing options...
joeg Posted August 8 Report Share Posted August 8 i'm looking to get the same sub... i was thinking of powering it with the rockford 1001db...what a wierd problem... it sounds like you have everything setup right... did you just get this amp? maybe its just defective?how do the alpine type R components compare to the fanatics? the fanatics run double the power.... are they clear? Quote Link to comment Share on other sites More sharing options...
gmoneyjive Posted August 8 Author Report Share Posted August 8 the 1001db would be a lot better choice than I have... the 1000a2 I used to have worked great...I'm starting to think it is defective (in the sense it just doesn't handle the heat quite as well as it should)... but I'm gonna try gain adjustments and a fan firstdunno about the alpine type r (been outta car stereo for a few years now, haven't been keeping up), but I've always loved the fanatic q's. I've heard people bitching about rockford components, but they've always turned out to be fanatic p or x, not q...I get a lotta compliments like "best mids & highs I've ever heard!" albeit from people who don't compete or anything. In fact one thing I notice right now is that the mids & highs go so loud without any distortion, they overshadow the base... and I end up thinking "where did the base go" (I can distinuish this from the amp problem tho ), and I turn it down a little and the base becomes more apparent. I also liked them cuz they had one of the higher power ratings (granted that doesn't say much by itself) of mass-produced component systems, and they have the advantage of more of them being found on ebay, thus driving price down... I just got a new set for $200 - retail is $430 Quote Link to comment Share on other sites More sharing options...
joeg Posted August 8 Report Share Posted August 8 yeah, i noticed on ebay theres only like a $50 difference between them and the type r's... i'll have to take a listen to em both at a local shop before i buy...good luck with getting the amp goin, lemme know how it works out for ya... Quote Link to comment Share on other sites More sharing options...
elementx Posted August 8 Report Share Posted August 8 Don't know if this was suggested... RF has a tendancy to get very hot. But I stand behind the amps 100%. Try to mount it at 90 degrees it helps the ventilation. Also add a fan if you must. Check the gains. Alot of people tend to put the gains too high when it really does not need to be at it's highest. Have you ever used / tried a Bass Capacitor (SP?)I am not all up and up on the Car Audio any more. I used to be. So I am just throwing out things that come to mind. A friend of mine has his Subs running off RF. He has the JL Audio subs in its original box. 2 -10" subs running off I believe the 800A4 bridged at 2 ohms . He only has the gains at about 1/2. The box pounds and he never has a problem with over heating. I am going by what I think is true. I am not 100% how he has it set up... He has a 2002 Alero and everything is stock except the subs. And the car sounds better than alot of the cars that I have seen with all kinds of work done. When I finally get my new car. I will also use the RF amps. And I want to get the JL Audio W7's. Incredible speakers... Quote Link to comment Share on other sites More sharing options...
Guest jroo Posted August 8 Report Share Posted August 8 you probably just have the gain set too high on the rear channels. question, i always thought it was better to run the subs MONO, not in STEREO , so why have two channels? is this something new that people do, or is it competetion type stuff? Quote Link to comment Share on other sites More sharing options...
gmoneyjive Posted August 8 Author Report Share Posted August 8 The gain was set high (on purpose)... anyway I just turned it down to the level of the front 2 channels, have to wait till lunch so I can run it long enough to heat up & see if it worked... but I'm still surprised that a power series amp would do thisWhy would mounting @ 90 degrees give it better ventilation? From my understanding it gets better ventilation with a horizontal mount, as heat rises straight up away from the amp, rather than parallel to the fins with a 90 degree mount - I could be wrong tho. I used to have a cap on my old system - but all that does is insure the amp gets enough power on hard bass hits, and that's not even an issue here.As far as I know, if you have the option of running bridged or stereo at half the load, (i.e. 4 ohm bridged or 2 ohm stereo) then amp will produce the exact same power, since either way will effectively cut the load in half compared to a normal 4 ohm stereo. On my old system I had that option - with two dual voice coil subs, each voice coil at 4 ohms... I chose to run 2 ohm stereo over 4 ohm bridged simply because that was where the max power bench test was given on the birth certificate of the RF amp. This time I don't really have that convenience, because I have only one sub, with dual 2 ohm voice coils, and it would not be wise to put 2 separate stereo channels (often containing different signals) into the 2 voice coils, thus I bridged it... still, it should be the same power either way. Quote Link to comment Share on other sites More sharing options...
gmoneyjive Posted August 8 Author Report Share Posted August 8 btw joe - is that your TT? Shit is tight!!! Quote Link to comment Share on other sites More sharing options...
joeg Posted August 8 Report Share Posted August 8 Originally posted by gmoneyjive btw joe - is that your TT? Shit is tight!!! not mine... but its what i'm hoping to model mine after... Quote Link to comment Share on other sites More sharing options...
Guest jroo Posted August 8 Report Share Posted August 8 all it has is rims, i dont see what the big deal is? something im missing because im not a TT freak? Quote Link to comment Share on other sites More sharing options...
gmoneyjive Posted August 8 Author Report Share Posted August 8 not that big of a deal, I just really like the way it looks... black with contrasting rims... that's all Quote Link to comment Share on other sites More sharing options...
Guest brwneydtrouble Posted August 8 Report Share Posted August 8 Originally posted by gmoneyjive I'd like to know what kinda crack u smoke. Sorry, guys. That wasn't me. It was a friend of mine that installs car and marine audio for a living. I was in the kitchen and he was using my PC, I was browsing C&B when he saw that question. I do not have nor do I profess to have any knowledge in car audio. In fact, I had Rockford Fosgate in my S2000......that I foolishly tried to install myself. Duh, didn't work, and I was dumb enough to have taken off the driver's side panel and took everything apart. Quote Link to comment Share on other sites More sharing options...
joeg Posted August 8 Report Share Posted August 8 Originally posted by jroo all it has is rims, i dont see what the big deal is? something im missing because im not a TT freak? just rims and tint... i like the premise that "less is more"i'm going for something similiar... Quote Link to comment Share on other sites More sharing options...
elementx Posted August 8 Report Share Posted August 8 Originally posted by gmoneyjive The gain was set high (on purpose)... anyway I just turned it down to the level of the front 2 channels, have to wait till lunch so I can run it long enough to heat up & see if it worked... but I'm still surprised that a power series amp would do thisWhy would mounting @ 90 degrees give it better ventilation? From my understanding it gets better ventilation with a horizontal mount, as heat rises straight up away from the amp, rather than parallel to the fins with a 90 degree mount - I could be wrong tho. I used to have a cap on my old system - but all that does is insure the amp gets enough power on hard bass hits, and that's not even an issue here.As far as I know, if you have the option of running bridged or stereo at half the load, (i.e. 4 ohm bridged or 2 ohm stereo) then amp will produce the exact same power, since either way will effectively cut the load in half compared to a normal 4 ohm stereo. On my old system I had that option - with two dual voice coil subs, each voice coil at 4 ohms... I chose to run 2 ohm stereo over 4 ohm bridged simply because that was where the max power bench test was given on the birth certificate of the RF amp. This time I don't really have that convenience, because I have only one sub, with dual 2 ohm voice coils, and it would not be wise to put 2 separate stereo channels (often containing different signals) into the 2 voice coils, thus I bridged it... still, it should be the same power either way. I was always told that mounting them 90degrees helps them relieve heat.... Don't ask me what the reasons are. I have no clue. But that is what I was told. And anyone that I personally know that put systems in did it that way unless they have a ventilation system. ( Fans ) and what not. Quote Link to comment Share on other sites More sharing options...
gmoneyjive Posted August 11 Author Report Share Posted August 11 turning the gain down didn't work, the fan apparently does, but I'm gonna send the amp back anyway cuz it shouldn't require a fan to operate under normal loads... anyway thnx for the help guys Quote Link to comment Share on other sites More sharing options...
Guest jroo Posted August 11 Report Share Posted August 11 Originally posted by joeg just rims and tint... i like the premise that "less is more"i'm going for something similiar... it looks good. im still looking for some rims that will set off my car. my car is black with 20% tint Quote Link to comment Share on other sites More sharing options...
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