Alpine PDX amps... setting gains with DMM?

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linksyz
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Hey guys... I tried setting the gains of my Alpine PDX 4.150 and 1.600 this weekend and when I plugged the DMM into the speaker plug... it wasn't reading anything... why is that?

I unplugged all speaker plugs, shoved DMM into one of the speaker plugs and plugged it into the amp. DMM was set to ACV and the wires on DMM were plugged in right two holes in the pic below. What am I doing wrong? I did have the head unit on with 1000hz tone on repeat...

digitalmeters_mas830_lrg.jpg


 
You need to use a 50 to 70 Hz test tone because not all DMMs can pick up outside of the frequency of household 110 AC voltage.

Ohhh thanks! Are you sure this is the only issue? My amp rack in 350z is REAL PITA to put in/take out as it's in the stock bose dept behind the driver's seat so I want to make sure I know what the problem is before I unbolt the rack.

I would like to hear from someone that has Alpine PDX amps and used a DMM to set their gains with it.

 
I would like to hear from someone that has Alpine PDX amps and used a DMM to set their gains with it.
It's inaccurate and mostly a waste of your time if you're trying match voltage to impedance with the "DMM setting method" math equation.

Don't look at the DMM, listen with your ears.

 
It's inaccurate and mostly a waste of your time if you're trying match voltage to impedance with the "DMM setting method" math equation.
Don't look at the DMM, listen with your ears.
That's what Bing from Simplicity Sound told me too... but I don't think my ears are quite "trained" yet so I listen to them... lol...

If I listen by ear... when should I stop turning the gain up? I read in a tutorial that you keep lowering the frequency on the head unit until the speakers start sounding distorted. So I should be lowering HPF on mids? I am running Focal 165 K2Ps 2-ways in passive on a 4 channel bridged amp.

 
The DMM is just a guide to get you in the ball park BUT you still need to use your ears to finalize the tuning!

The only thing I have used the DMM method for was to set an amplifier to deliver less RMS power to my subwoofer because that amplifier puts out enough RMS power to send the sub to its grave. I still had to tune by ear afterwards.

 
My comps amp puts out 300x2 in bridged and I know several people that gave 300 per side to Focal 165 K2Ps in passive even though they are rated 100RMSx2. Also, my sub is rated 500RMS (DLS Iridium 10") and my 1.600 is 600RMS so I know that even if I turn the gains ALL the way up that neither my comps or the sub will be sent to the grave. I think I currently have comps at around 75% and sub around 90%.

I am real new when it comes to tuning the system and I have no idea how to even set up my Parametric EQ. However, I do plan on getting the system RTA tuned in near future by a pro.

 
Which head unit do you have?

You don't need to set your gain if the preamp voltage is sufficient to drive the speakers to your desired loudness. A gain knob is a sensitivity attenuator that allows you to add voltage to the speakers.

Always drive the system from the HU volume first and add only the amount of amp gain needed to run a sufficiently loud, but undistored sounding system. A DMM is usless in this regard as i cannot sense when the system is stressed. The "DMM method" is not even ballbark, it's outer space.

Trust me, you ears a good enough....you just need to practice a little. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 
This is how I did it..I ran a 100hert tune set my voltages acording..Then I turn up the gain acordingly and stop turning up the gain when I feel confertable with that volume and that sound quality..I have a 800rms amp running my fronts..But I have very little gain, if any on the amp, and the speakers are still running fine
Oh yeah, like the OP should be taking advice from someone who couldn't even connect his subwoofer amp properly:rolleyes:

http://www.caraudio.com/forum/showthread.php?t=384840

This was the best part: http://www.caraudio.com/forum/showpost.php?p=5857327&postcount=53

 
Hey guys... I tried setting the gains of my Alpine PDX 4.150 and 1.600 this weekend and when I plugged the DMM into the speaker plug... it wasn't reading anything... why is that?
I unplugged all speaker plugs, shoved DMM into one of the speaker plugs and plugged it into the amp. DMM was set to ACV and the wires on DMM were plugged in right two holes in the pic below. What am I doing wrong? I did have the head unit on with 1000hz tone on repeat...

digitalmeters_mas830_lrg.jpg
you should never shove anything into an amp //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 
you should never shove anything into an amp //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif
Beg my pardon... I "inserted it gently" into the speaker plug.

Better? //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif

 
Which head unit do you have?
You don't need to set your gain if the preamp voltage is sufficient to drive the speakers to your desired loudness. A gain knob is a sensitivity attenuator that allows you to add voltage to the speakers.

Always drive the system from the HU volume first and add only the amount of amp gain needed to run a sufficiently loud, but undistored sounding system. A DMM is usless in this regard as i cannot sense when the system is stressed. The "DMM method" is not even ballbark, it's outer space.

Trust me, you ears a good enough....you just need to practice a little. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
My head unit is Alpine 9887 and the max volume on it is 35. I don't think my speakers get loud until I turn the volume to 23-25 and 27 is real loud, but at 27 my sub goes crazy and there is still no distortion from the speakers. I think I should turn the comps amp's gains up a little bit and turn the sub's gains down a little bit.

I know that when you set the gains with DMM that they say turn the volume to 80% of the max volume or the max volume you are comfortable turning your HU to. That being said, if DMM is reading let's say 200 watts per side at volume 25, and I turn it to volume 30 and there is still no distortion, that means that speakers can handle that 200watts plus wattage between volume 25 and 30, right? By the way, my HU has 4v pre-outs.

 
That being said, if DMM is reading let's say 200 watts per side at volume 25, and I turn it to volume 30 and there is still no distortion, that means that speakers can handle that 200watts plus wattage between volume 25 and 30, right? By the way, my HU has 4v pre-outs.
Your DMM's not reading watts. But that's kind of besides the point, here.

Just take the loudest, most dynamic music track and put it on repeat. Turn your amp gains to minimum and crank you HU to 30-32 out of 35 (assuming the output is not linear and 35 is clipping). Add gain in small increments or have a friend slowly add a little until you're satisfied with the volume.

Your HU preouts are rated at 4v MAX power. You won't get 4v until you're at 35/35 with a 0 dB tone playing. The RMS of a 0 dB tone is about -3 dB. Most modern music is about -10-12 RMS. Just threw that in there so you understand what's going on with playing tones and using your DMM.

 
If his 9887 is like my 9885s, I highly doubt the subwoofer output EVER hits 4 volts //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif I am going to verify clipping and voltage output with my oscilloscope when I replace one of the 9885s with a 9887 in the near future!

 
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