Alpine gain setting

[naiku 10+ year member]

I have an Alpine MRV-F345 on the way, but after reading the manual online am a little confused about setting the gain. It appears that this amp does not have the regular dial, so I can't use the multimeter method.

What it does have is a digital display from 0.2-4v which it says is used to "Adjust the input level of the amplifier to match the output of the connected head unit" so does this mean I should set it to 2v because my HU has 2v pre-outs? if not, how do I set my gains?

Thanks.

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[DejaWiz 5,000+ posts]

Instead of a dial, it's a digital setting. You set it and measure it with the dmm just like you would if it were a dial.

Alpine just says to set it to your HU preout volts in order to simplify installation for those that don't know.

 

[Grim 10+ year member]

Yeah you def set it with the DMM....The only problem is the increments are bigger(i have the same amp just a bigger model, and the M1005) I had to get close to where I needed to be, and then adjust the Headunit EQ a little bit to get the voltage to where it needed to be.

 

[naiku 10+ year member]

Great, thanks for the replies. I did a bit more searching around yesterday and figured it would still be with the DMM but could not get it exact.

My next question, is it Ok to run some 2 ohm speakers on Ch 1+2 and a 4ohm sub bridged on Ch 3+4? The reason I ask is that the Alpine manual only lists RMS power at 2 ohms on channels 3 and 4.

 

[DejaWiz 5,000+ posts]

Yeah, it should be able to handle that.

Channels 1 and 2 are rated for 85WPC RMS at 2 Ohms and 3+4 bridged is 300W RMS at 4 Ohms.

 

[naiku 10+ year member]

Yeah, it should be able to handle that.
Channels 1 and 2 are rated for 85WPC RMS at 2 Ohms and 3+4 bridged is 300W RMS at 4 Ohms.

Thanks again, I figured it would be OK. This amp is confusing me though, you say that its 85 RMS at 2 ohms, yet on the owners manual I downloaded it says 150 RMS at 2 ohms. I calculated my gains at 100 RMS (rating on my speakers) and got 14.14v. The gain I then calculated for the sub comes out at 34.64v. Now for the first part, when I try to set the gains with my DMM I go all the way down to 0.2 on the amp, and still don't get the desired voltage. For now I turned the gains down a little, as I don't want them both to be at the maximum. Any idea's on this?

Also, in the owners manual it shows that when setting up a 3 way system (as I am doing) to set the input selector switch to CH1+3 and CH2+4 which it says sums the 1 and 3 input and sends to ch3, and sums 2 and 4 and sends to 4. Yet the diagram clearly shows 2 sets of RCA's, and the instructions also say to set the switch to Ch3/4 when using a HU with dual pre outs (I am). So where do I set this switch?

Sorry for all the dumb questions, the owners manual does not make too much sense logically. I can't do much today though, the weather is sh*tty. I also have a poor ground that I need to get cured before I do too much more.

 

[DejaWiz 5,000+ posts]

1. This amp is confusing me though, you say that its 85 RMS at 2 ohms, yet on the owners manual I downloaded it says 150 RMS at 2 ohms.

2. I calculated my gains at 100 RMS (rating on my speakers) and got 14.14v. The gain I then calculated for the sub comes out at 34.64v.

3. Now for the first part, when I try to set the gains with my DMM I go all the way down to 0.2 on the amp, and still don't get the desired voltage. For now I turned the gains down a little, as I don't want them both to be at the maximum. Any idea's on this?

4. Also, in the owners manual it shows that when setting up a 3 way system (as I am doing) to set the input selector switch to CH1+3 and CH2+4 which it says sums the 1 and 3 input and sends to ch3, and sums 2 and 4 and sends to 4. Yet the diagram clearly shows 2 sets of RCA's, and the instructions also say to set the switch to Ch3/4 when using a HU with dual pre outs (I am). So where do I set this switch?

Sorry for all the dumb questions, the owners manual does not make too much sense logically. I can't do much today though, the weather is sh*tty.

5. I also have a poor ground that I need to get cured before I do too much more.

1. Ah, the OM does say that. Sorry, I was looking at the specs at sonicelectronix.com then I dl'ed the manual to verify.

2. Yep, those figures are right for 100W @ 2 Ohms and 300W @ 4 Ohms.

3. What kind of test tone or music are you playing while setting the gains?

4. 1+2 = front left and right, 3+4 = rear left and right. Sum 1+3= front+rear left sent to channel 3 and Sum 2+4=front+rear right sent to channel 4. Now your HU's fader shouldn't affect the sub's output (I think this is how it works out). You can keep the switch on the 3/4 setting if your HU has dedicated sub preouts.

5. Definitely get everything grounded properly before testing and tuning takes place. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[naiku 10+ year member]

1. Ok, glad I am not going crazy //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

2. Good! //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

3. Using -3dB test tones, 60Hz for the sub, and think something like 1kHz for the speakers.

4. My HU has the sub pre-outs, so will leave the switch on the 3/4 //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

5. If it ever stops snowing, I can try to get the ground sorted!! Will then re-check the gains.

Thanks for all the help.

 

[DejaWiz 5,000+ posts]

Good luck bud, and let us know how it goes.

 

[luvinthebass 5,000+ posts]

1. Ok, glad I am not going crazy //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
2. Good! //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

3. Using -3dB test tones, 60Hz for the sub, and think something like 1kHz for the speakers.

4. My HU has the sub pre-outs, so will leave the switch on the 3/4 //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

5. If it ever stops snowing, I can try to get the ground sorted!! Will then re-check the gains.

Thanks for all the help.

are you settin the system up with the speakers connected while usin the tones, if ya are that 1khz tone at clippin is easy as hell to hear, the 60 hz kind of difficult, good luck