New to car audio, please help with a few issues

[MillerSHO 10+ year member]

First time poster, just saying hello and hoping to get some input on an issue after the install (I hope I'm posting this in the correct subfourm).

After playing various types of music for 30-45 minutes the amp will cut out for a few seconds and come back on. I believe the amp is protecting itself due to the fact that the amp is very hot to the touch and I can smell it also. This amp has never cut out any other time, it's only when playing it loud for a while.

The amp is alpine F450 (old AB), the 10" type S sub is bridged on channels 3 and 4 and I have Hertz HSk165's in stereo on channels 1 and 2.

Is this due to the old AB style amp? There's no fan on this amp, just heat sinks on the top. Gains are set to 60% on channels 1/2 and 75% on channels 3/4.

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[audioholic 5,000+ posts]

There is no such thing as setting gains by %, you match the gains based on the input voltage. In some situations, even setting the gains at "10%" is too much and the volume control must be used to limit voltage output/input to the amplifier.

Based on the limited info you've posted, the problem could either be a gain setting, or a system voltage problem.

 

[MillerSHO 10+ year member]

Thanks for responding, sorry for the lack of info I'm still wrapping my head around everything.

Sounds like I need to read up on matching the amp gains to my 4volt HU. I'll give that a shot.

 

[MillerSHO 10+ year member]

Not sure if anyone is listening but for the sake of following up on a thread I created (Hate when I do searches for a problem and the OP doesn't list updates) I think I have my gains pinned down.

The max volume setting on my HU is 35, if I times that by .8 that's 28 which puts me right about where I'm at right now for my max volume with the gain settings set to "nom" on channels 1 and 2.

I'm going to set channels 3 and 4 to "nom" as well and see how it goes, I think having channels 3 and 4 set to +.5 is too much and it's probably clipping.

Either way I don't think I'm going to be in a better situation when it comes to the amp and it reaching it's thermal max, not sure what to do about this.

Is this just normal for an AB amp being push to it's limits all the time?

I wonder if just getting the dead air in the amp moving even just a little it would keep it cool enough.

 

[cfox10 10+ year member]

What sort of power and ground are you running? Could be too small of wire. You should try and get hold of a DMM to set gains, and what ohm load is each channel seeing?

 

[dragnix 5,000+ posts]

Did ya wire it correctly? Could be too low of an impedance for the amp

 

[MillerSHO 10+ year member]

What sort of power and ground are you running? Could be too small of wire. You should try and get hold of a DMM to set gains, and what ohm load is each channel seeing?

Power and ground are 4 gauge.

Channels 1 and 2 are 4ohm and Channels 3 and 4 are bridged so I assume they are 2 ohm.

Amp specs say its stable at 2ohms.

I had the wife in the car with me today so I never turned up the volume at what I listen to and the amp was barely warm to the touch and this was running the setup for about an hour.

 

[MillerSHO 10+ year member]

Did ya wire it correctly? Could be too low of an impedance for the amp

I believe so.

The only thing I can think of is I used the factory wires in the door and even then I ran the larger gauge until it came time to go into the door. All other speakers have new larger gauge wiring.

 

[audiobaun 5,000+ posts]

Alpine MRP-F450 (mrpf450) 4-Channel Amplifier - Sonic Electronix

Specs on the amp

 

[dragnix 5,000+ posts]

You said amp is stable at 2ohms, is that bridged? Most multi channels amp are stable only to 4ohms when bridged

 

[audiobaun 5,000+ posts]

Alpine SWS-10D4 Type-S 10" subwoofer with dual 4-ohm voice coils at Crutchfield.com

Specs on the sub..depending on how you have that sub wired, you are @a 2ohm load, or you can wire to an 8ohm load using both coils here

Subwoofer Wiring Diagrams, One 4 ohm Dual Voice Coil (DVC) Speaker

You can hook up one set of coils, and run that sub just fine on that amp @4ohms no problem@1/2 the rms factor..one pos,and one negative on one coil same as a single voice coil sub,and you will be @4ohms on the sub, which is what the amp is rated for on a bridged/mono channel of ch 3,and four..you will be only feeding 1/2 of the rms rating on that sub of 250rms@4ohms, and not both coils of 250x2@500rms..you are going to fry that ch of 3,and 4 if you dont bring it back down to the 4ohm stable load..just some info, that I found from looking up specs..Run one side of the subs coils= one Pos, and One neg on one side of the sub for a 4ohm load that the amp can handle

 

[MillerSHO 10+ year member]

You guys are awesome.

I bought the sub already in the box from my good friend so I'll take the sub out and see how it's wired, it sounds like I'm forced to run it at 8ohms to make it stable.

What I don't understand is my friend ran that sub and amp (I bought the amp from him also) exactly how I'm running my setup and never had overheating problems. He did have different fronts but I don't see how that could tip the scales.

In the end it sounds like the sub and amp do not play well together, what are my options?

Quit playing around and get a single channel amp for the sub(Run two amps) or buy a sub that will run at 4ohms when bridged or run each voicecoil to a channel on my current amp?(Not sure if my box has hookups to allow both voicecoils to be wired separately

 

[audiobaun 5,000+ posts]

You guys are awesome.
I bought the sub already in the box from my good friend so I'll take the sub out and see how it's wired, it sounds like I'm forced to run it at 8ohms to make it stable.

What I don't understand is my friend ran that sub and amp (I bought the amp from him also) exactly how I'm running my setup and never had overheating problems. He did have different fronts but I don't see how that could tip the scales.

In the end it sounds like the sub and amp do not play well together, what are my options?

Quit playing around and get a single channel amp for the sub(Run two amps) or buy a sub that will run at 4ohms when bridged or run each voicecoil to a channel on my current amp?(Not sure if my box has hookups to allow both voicecoils to be wired separately

It would be recommended to get another amp for that sub to run at its full potential,and keep that alpine running your others/components, but you still have the option to run that sub @4ohms mono,on one set of coils@250rms, till you get the other amp for 2ohm stability to run that sub full potential of 500rms,on both coils.I dont recommend running the amp for each coil with one amp, or even two other amps..For one thing, its a real PITA,to set the gains right for both coils to hit properly.Better to get /work off one ch bridged/mono, or get a mono amp to work with, to keep things simple/rather than complicate things, though you can run that 4ch ,2chs bridged for ea coil, but ive always ran into issues even after setting gains properly..Its not advised by my experience..its just a real PITA to be dealing with.

Just my 0.02cents

 

[MillerSHO 10+ year member]

It would be recommended to get another amp for that sub to run at its full potential,and keep that alpine running your others/components, but you still have the option to run that sub @4ohms mono,on one set of coils@250rms, till you get the other amp for 2ohm stability to run that sub full potential of 500rms,on both coils.I dont recommend running the amp for each coil with one amp, or even two other amps..For one thing, its a real PITA,to set the gains right for both coils to hit properly.Better to get /work off one ch bridged/mono, or get a mono amp to work with, to keep things simple/rather than complicate things, though you can run that 4ch ,2chs bridged for ea coil, but ive always ran into issues even after setting gains properly..Its not advised by my experience..its just a real PITA to be dealing with.Just my 0.02cents

Audiobaun, thank you again for the help.

So if I'm understanding you correctly I can run one voicecoil in a dvc speaker without harm? Good info, I had no idea.

Just be clear are you saying I can run channels 3 and 4 bridged to the one voicecoil so I can still run as many watts as I can at 4ohms until I upgrade to a dedicated sub amp?

Thanks again

 

[audiobaun 5,000+ posts]

Yes you can run one coil on the sub,but it will be 1/2 the rms rating on that sub,and ohm load..The sub you have is DVC4ohm/2-4ohm coils,and at 500 rms total on both coils for a 2ohm mono mode,so 1/2 of the rms would be 250 rms,on one set of 4ohm coil running at 4ohms in which the amp is stable @4ohms mono you have. by bridging your amps ch 3,and 4 in mono mode/lpf, you will be in bridged/mono mode for 4ohms mono stable,.Running at 250 rms for that sub on one set of coils,not as many watts as you want.You might be able to go a bit more depending on how well that sub handles power without clipping,maybe 50-100 watts?Just depends on where the sub runs clean at/not clipping/bottoming out,this will be trial and error testing on your behalf..every sub is different,even the same model.But yes you can run the sub on one set of coils at 1/2 the recommended rms value, and be just fine, as long as you set the gains cleanly, and no clipping issues..Dedicated meaning an amp for the sub/subs only, nothing else/dedicated.Ive never had any issues running one set of coils on any of my dvc sub when needed..Doing so now on a pair of Kicker CVR dvc 4ohm subs running one coil per sub @2ohms for the pair,