7genmarathon

iTrader: (1)

Finally installed on of my stuff, im setting the gains multi-meter method, but while increasing my gains, i only get a small increase of voltage out of my speaker terminal, nowhere near its recommended level of output voltage.
Here are the specs

4Ch RMS 75x4 @ 4ohm (using all four channels, no bridge)
mono RMS 360x1 @ 2ohm (parallel, nothing wrong here)

4AWG Power+Ground
8AWG pwr d.block to both amps
8AWG gnd d.block to chassis
3 RCA cables

Everything works great, I just can't figure out setting the gain the DMM method. and im using an analog multi-meter..not digital..no difference.

Using the formula V=sqrt(watts x ohms) in my case V=sqrt(75x4), V=17.32

Im getting nowhere near 17.2. I cannot ever get above 5volts output on the speaker terminals..I might be doing the formula wrong too..

Im using both 50 and 60hz test tones, all the HU, Xover, boosts are off or not used. The only setting is -6db phase on the HU

The 4ch amp has input lvl of 400mV-5V(matches HU)
The HU has preamp voltage @ 5V (pioneer DEH-p780mp)

When I get the gains set right I will most def post pics of the install and final instal!

Kennykid2002

iTrader: (1)

Your formula is correct, but you should be getting 17.3V

Make sure you are using a 60hz test tune set to -6db
Since you are using the method to setting your gain on a 4 chan amp, it might be slightly different.
Make sure you're using a CD

Turn off all bass boost, EQ, and everything.
Set volume as loudest you'll listen to
Play test tune on repeat.

Increase gain until you reach 17V, if it doesnt reach that high, turn up the LOW setting on the headunit until it reaches around 20V and turn down the gain slightly till you have 17V

Do the same with the mono amp, except turn up the SUB and tune down the gain if you cant reach your desired voltage

7genmarathon

iTrader: (1)

When you say "60hz set to -6db" how would I go about setting it to -6b on the comp? on the HU I have the sub set to -6db slope

Heres where im getting my test tones, using 60hz
http://binkster.net/extras.shtml

4ch amp amps good. Runs cool @ 17.0-17.2

Sub amp aint reaching 26.8 Volts. Sub is turned up to +6, all eqs, filters, boosts on amp and HU are off.

suggestions?

Kennykid2002

iTrader: (1)

Edit the test tone on Audacity, set it to -6db
Make sure the audio file is not MP3, use WAV or any other uncompressed format

If you set sub to -6db, that's why your sub is not getting the voltage it needs.
turn max gain, see if you get the voltage if not, slowly turn up SUB one by one until you pass 27V, then tune down the gain

7genmarathon

iTrader: (1)

FYI FINALLY had time to get the gain set. You were right, HU was set to -6b. Set it to +6, got it to its volt range bearly cranking the gain to 1/4 or may 1/3 of its full setting. It bumps and sounds great with now that both amp gains are set accordingly. Awesome soundstage i cant believe what little setting the gain can do to you car audio performance!

Thanks very help sir!

Kennykid2002

iTrader: (1)

Glad you got it all sorted out