ShIft_uR FacE

iTrader: (4)

I have a couple questions regarding my amps and speakers...hopefully i can get some help.

1. I currently have an Alpine mrp-f450 to power my speakers. I have alpine type r components up front and alpine coaxials in the back. Recently i disconnected the rear speakers from the amp and bridged just the fronts. When i went to connect all 4 again, my first channel would not work on its own, only when bridged with the second channel. Whats wrong? How can i fix this? I am running just the fronts at the moment again bridged.

2. On certain songs, the highs seem to crackle at higher volumes during certain parts. Is that the amp telling me im running too much power or not enough?..or is it just the song? The amps gain is set to less than 3/4 and it usually only happens to the passenger side.

3. I recently installed an alpine type r 12" sub into my car. Im powering it with a Hifonics brutus 1200watt. It is "said" to be able to put out 900 watts @ 2 ohms which i knew would not be the case but i was hoping for at least 400 rms...it does not seem to even put out that. I have the sub in a sealed box made to alpines specs. My problem is...even at full gain set on the amp, the subwoofer doesnt seem to move like it should. I have the bass boost on the amp off but am running it at +8 on my alpine headunit (cda-9855) which ive heard is bad for the sub. I used to power 2 12" rockford p3's prob over a year ago with this and they hit alot harder..it was wired to 1 ohm tho. Is there any way to check if there is something wrong with the amp or should i invest in another one?

Thank you in advance.

nismos14

iTrader: (56)

Something internal on the amp, you possibly/probably have a blown channel on the amp


Could be an internal amp problem or too high of a gain setting.

The Hifonics typically do right at rated power, sometimes slightly more or less. The amp is not the problem, alpine sub pre-outs are notoriously weak. What you can do is set the sub to sytem 2 for a slight boost in the preout signal from the HU, also a line driver could help on the sub output.

Hope that helps.

ShIft_uR FacE

iTrader: (4)

1. Im guessing the channel is blown as well but i figured it wouldnt work when bridged if blown?

2. Might be the gain because i dont think it occurs when put into a single channel.

3. The radio has a 4 volt preout...what is system 2?

Where would i go to get the amp tested?

nismos14

iTrader: (56)

If a channel blown, it could still work bridged.

Check out the gain then, turn it down slightly

Yes I know, it is still weak, and if you measure it I gaurantee it won't read anywhere near 4 volts. If you go into menu, and select Audio, then Subwoofer system it should allow you to change to system 2.

ShIft_uR FacE

iTrader: (4)

Ill try it out. Thank you very much. BTW...Does anyone know the correct radio dash kit for the 5.5 gen max? There are a couple on ebay...

shorterthanrich

Holy crap turn the gain down. You're going to blow your amp and sub if you have the gain all the way up. Doesn't matter if its underpowered or overpowered...you blow **** up with maxed gain.

Lower gain until sub distortion goes away, turn down bass boost on your HU, and definitely leave your amps bass boost off.
Its possible you have it wired incorrectly (no offense). Hifonics usually does rated power.

Regarding the crackling...sounds like a blown speaker/bad channel on the amp.

ShIft_uR FacE

iTrader: (4)

My sub has no distortion? And no offense taken but its wired correctly to 2 ohms...dual 4 ohm voice coil sub with + to + and - to - with power wires going to the + and - on the outside.. ex: *-,+,-,+*. Ive used 4 gauge and 8 gauge for power & ground to the amp with the same results. Im going to try changing the setting on my headunit to system 2 like was before mentioned to see if there is any difference.

Regarding the speaker, if its blown it would always happen correct? Its only during certain songs if i have the volume UP..and i believe its usually vocal ex: the intro to rick ross ft r.kelly - speedin.

shorterthanrich

With the gain all the way up you're certain to be getting some square waves. Do you have an oscilloscope? Using one is the best way to set the gain correctly.
That does seem wired up correctly. Though I'd definitely use 4AWG or less all around. No reason to be using 8. But I'm just nitpicking and thats probably not the cause of the problem.

I actually have a similar problem with my tweets. I plan on replacing them very soon. I'm not 100% certain of the problem. Its just the stock bose system. I don't think the amp is the issue, but I could be wrong...

And BTW, sorry I didn't mean to sound condescending in my post earlier about the gain and whatnot. It just terrifies me to hear gain at max. I actually had a nightmare about it last night - not even kidding.

ShIft_uR FacE

iTrader: (4)

No i dont have an oscilloscope. The only reason i had the gain set that high was because i wasnt getting enough power to the sub so i thought it was the amp...for some reason i still think it IS the amp...i just have no way of checking it besides installing it in someone elses car or connecting another amp in my car. I tried setting the subwoofer to system 2 as nismo suggested but it made no difference. The only way for me to get better bump from the sub is turning the mx effect from the headunit on and i dont think thats something i should be using. I know 4 gauge is recommended but ive used both and see no difference in power to the sub. Can the 12 gauge wire im using to connect the sub to the amp be the problem? I dont see how much bigger i can actually use. Im stumped. I have no idea whats going on

shorterthanrich

I figured you had the gain all the way up to try and get more out of it, but you'll do more harm than good. You'll just blow the sub or amp if you havn't already.
You can check the amps output with a multi-meter and on oscilloscope rather than installing it in another car. Since you don't have those, find someone who does. Have a handy mr fix it friend? know an electrical engineer or EE student? A friend or relative who's an electrician?
Really, this is the easiest way to tell if the amp is outputting correctly at your settings. more people have multimeters than you may think.
You probably wouldn't notice a difference with 8 or 4AWG for the ground, but the 8 is probably getting hotter than it should, etc. You're probably fine but if you're aiming for 900 watts 8 is wayyyyyyyy too small.
12 awg to the sub should be fine. thats pretty good sized wire for that.
what is the mx effect and why shouldn't you use it?

your wiring sounded right, but just for good measure..
http://www.crutchfield.com/learningc...4%2Dohm%5Fmono

what do you have the sub crossover set to?
subsonic filter?
phase shifter?

also...how bad is it? you're saying its not pushing enough...but give me a gauge here. 2 p3s would be way louder than just one type R. Much more surface area + more power. so how bad is it?

ShIft_uR FacE

iTrader: (4)

The mx stands for Media Xpander which the manual says "will allow radio to reproduce music clearly even in cars with lots of road noise; when using cd, processes a large amount of data during playback, allowing for clearer & cleaner output; makes vocals or instruments sound distinct regardless of the music source".

There are also 3 settings in tuner mode...stable, normal and hi-fi. This helps a bit with the bass reproduction depending on how i set it but nothing special.

Im using the headunits crossover and at the moment it is set at 80 hz i believe using an LP cutoff. Subsonic filter on the amp is between 15 and 35hz...phase is set to 0.
And well...its pretty bad. With the amp at 3/4 power, no bass boost from either headunit or amp and settings at normal without any audio processor help i probably get more bass from my mids. Its easy to tell the thing is underpowered if i open the trunk and turn the volume up...the sub hardly moves.

nismos14

iTrader: (56)

You can adjust the sub level on the HU, putting it up to 15 will still not give you a clipped signal, have you adjusted the sub level at all? (Not EQ, but sub level itself).

ShIft_uR FacE

iTrader: (4)

Yes ive played with it (no ) and of course it helps alot but isnt that the same as using the bass boost on my amp = bad?

nismos14

iTrader: (56)

Not at all. It is adjusting the overall level. Not a boost at certain frequencies.

pikers

15 on an Alpine = 0 on everyone else's HUs. The idea is to dial back sub output from a clipless output at 15, so you cannot turn up the sub too high.

Is your sub out of phase? I can't imagine why you don't hear anything.

ShIft_uR FacE

iTrader: (4)

Well thats good to know. No its set at 0 on the headunit and the amp. Never said i didnt hear anything just that it stayed very low without help from the audio processor or bass boost on headunit.