I bought my amp (Alpine MRP-F550) over a month ago, but finally got it
installed only 2 weeks ago. At turn-on, I've noticed it has a LF hum
(70hz?) that slowly damps out (10-40 secs). It happens whether I turn
the key to start or accessory and is not dependent on volume. I also
found that it doesn't happen every time I turn it on, only if it's been
sitting off for a few minutes.
Has anyone experienced this or have any theories as to why it's happening?
Although I did not personally install the amp, I know from talking to the installers that the preamp lines are run on the opposite side of the truck from the power wire. I also suspect the issue isn't the RCA jacks touching something metal, as I would expect the hum to be present constantly or at least intermittently. As it is, the amp only hums at turn-on and only after it's been off for at least a few minutes. It's never hummed while on nor immediately after being turned off. As for "making sure my frequencies aren't too high", I'm not sure what you are referring to. The amp is running door speakers that are almost full range (using the amp's built-in high-pass crossover at 60 Hz). Although I did not personally install the amp, I know from talking to the installers that the preamp lines are run on the opposite side of the truck from the power wire. I also suspect the issue isn't the RCA jacks touching something metal, as I would expect the hum to be present constantly or at least intermittently. As it is, the amp only hums at turn-on and only after it's been off for at least a few minutes. It's never hummed while on nor immediately after being turned off. As for "making sure my frequencies aren't too high", I'm not sure what you are referring to. The amp is running door speakers that are almost full range (using the amp's built-in high-pass crossover at 60 Hz).
If you'll read my initial description again, you'll notice that the problem:
Fades after 10-20 seconds, so I can't tweak and adjust to my hearts content
Still occurs even with no RCA preouts (aka the stereo) connected, so the volume of the stereo has no bearing on this issue. Plus, the gain is set to nominal, so I doubt that's the issue. If you'll read my initial description again, you'll notice that the problem: Fades after 10-20 seconds, so I can't tweak and adjust to my hearts content Still occurs even with no RCA preouts (aka the stereo) connected, so the volume of the stereo has no bearing on this issue. Plus, the gain is set to nominal, so I doubt that's the issue.
I'll be the first one to admit I'm wrong, so here goes. When I mentioned that the gains were set to nominal, I hadn't actually checked them recently. When I went to tweak something on the amp today, I notice one gain (ch1&2 or 3&4, not sure which) was set slightly above nominal. A quick tweak back down, and it seems the hum has gone! So while I'm not sure why a gain adjustment fixes an issue that occurs even when the stereo is not connected, I'm glad its gone!I'll be the first one to admit I'm wrong, so here goes. When I mentioned that the gains were set to nominal, I hadn't actually checked them recently. When I went to tweak something on the amp today, I notice one gain (ch1&2 or 3&4, not sure which) was set slightly above nominal. A quick tweak back down, and it seems the hum has gone! So while I'm not sure why a gain adjustment fixes an issue that occurs even when the stereo is not connected, I'm glad its gone!
You can't post conmments that contain an email address.
Make sure your rca jacks arent touching any metal and your hot (+) cable is not ran on top of your rca jacks and check and make sure your frequencies arent too high
turn your gain level down and turn your radio up slowly add the gain level if it stops your amp is too high turn down enough till sound stopsturn your gain level down and turn your radio up slowly add the gain level if it stops your amp is too high turn down enough till sound stops
You can't post conmments that contain an email address.
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
Any time that there is a rattling sound from the subs, that indicates that they are probably blown. How were the subs tested ok? If the resistance of the subs is still close to OK, that is good, but it doesn't necessarily indicate that they are working properly. Try using different subs at a lower volume, or turning down the gain slightly.
It sounds like the amp is at max power and is saving itself from frying.Different makers have different methods.If you want to you could call Alpine to verify it if you want but I bet they will say about the same thing.Good luck! Greg
Have you tried checking the remote wire yet? Because it could very possibly be that. Without a remote wire hooked up, you cannot get any power. Try that and see if it works.
main problem i think you are having is your loosing power when it kicks a note.. get a power cap! power caps feed your amps constant power! this will solve your problem :)
as far as it staying on it may have been wired to your hot unstead of your remote on your radio
when it runs wide open it gets hot
how are your gains
I have an alpine and I just hooked up jl 12 w3s and it kinda j did what yours did
it played.. hit hard then no subs.. my mids and highs platyed, but until I would turn off the car and restart the radio the subs immediately came on and the subs are only connected to this aplpine mrp m 650 amp
what speakers and what ohm did they wire it too?
i think my problem was I was overloading my amp feeding it a 2 ohm load or a one ohm load and it was shutting down my subs.. protectection I suppose?
im having the same problem with my amp, I took it to best buy and they said the amp was recieving power and recieving signals from the deck and i had everything hooked up right but that in the circuit board all the connections were blown, meaning i have a blown amp, i hope this isnt your problem but it definetly sounds like it. GOODLUCK
Although I did not personally install the amp, I know from talking to the installers that the preamp lines are run on the opposite side of the truck from the power wire.
I also suspect the issue isn't the RCA jacks touching something metal, as I would expect the hum to be present constantly or at least intermittently. As it is, the amp only hums at turn-on and only after it's been off for at least a few minutes. It's never hummed while on nor immediately after being turned off.
As for "making sure my frequencies aren't too high", I'm not sure what you are referring to. The amp is running door speakers that are almost full range (using the amp's built-in high-pass crossover at 60 Hz).
If you'll read my initial description again, you'll notice that the problem:
Plus, the gain is set to nominal, so I doubt that's the issue.Fades after 10-20 seconds, so I can't tweak and adjust to my hearts content
Still occurs even with no RCA preouts (aka the stereo) connected, so the volume of the stereo has no bearing on this issue.
I'll be the first one to admit I'm wrong, so here goes. When I mentioned that the gains were set to nominal, I hadn't actually checked them recently. When I went to tweak something on the amp today, I notice one gain (ch1&2 or 3&4, not sure which) was set slightly above nominal. A quick tweak back down, and it seems the hum has gone! So while I'm not sure why a gain adjustment fixes an issue that occurs even when the stereo is not connected, I'm glad its gone!
×