setting gain for sub amp ....settings on HU?

[93civEJ1 10+ year member]

ok I want to set the gain for my sub amp.

I have a pioneer AVH-P3k series HU.

Do I need to turn the subwoofer setting on the HU to on while setting? ...if so, do i use any crossover setting on the amp itself or control from the HU? I know when I set the front stage I put everything to flat.

If I turn my subwoofer setting to on, will these do anything to my rear speaker setup I am running just off the HU rear speaker wires?

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[93civEJ1 10+ year member]

I guess I am a little confused on this because it has 3 pre-outs...the manual says the rear speaker leads or RCA can be used to control a subwoofer with the subwoofer setting turned on.

So If I use my actual subwoofer preout, then what does that mean? just leave that setting off and everything flat still and only control from the amp?

 

[93civEJ1 10+ year member]

ok...i am trying to run 100 rms on 1 10" ...i set the amp to flat (instead of bass / treble).....I could not get any voltage reading until i turned on the subwoofer setting to ON on the headunit. I set it to see 20 volts (on a 2 channel amp bridged)...i used the DMM to set the gain using the postive and negative from each of the two channels and set it at 20volts during a 50hz sine wave at my max 3/4 volume. Now when I turn music on, the subwoofer is working, but no where near what I figured it would be sounding like. did I do that right?

 

[93civEJ1 10+ year member]

I need about 50 more rms watts out of the amp to get the continuous 150 rms out of the sub I want. the rms for the amp I am using is 50 watts rms per channel (2 channel)...so I am only guessing its 100 rms for bridged setup. Whats the downside to turning up the gain some more on the bridged connection? frying the amp? ...if so I wouldnt care about that because it was free and its an el cheapo.

 

[destined2race 10+ year member]

If you have a sub preout, use that. Then you should have a dedicated subwoofer control on your deck that will adjust gain... ie so you dont have to physically turn the amp down if you want to turn the bass down for a while. Works better than running off your rear output and fading to the front when you want less bass.

You should have your filter on your amp to LP and typically people set the crossover Fq from 60-80hz depending on setup. with your ten id go closer to 80. Avoid using bass boosts if it has it and if it has subsonic set it to around 30hz.

What kind of amp and sub do you have and what kind of box is it in. also what kind of vehicle, by your name a 93 civ?

 

[93civEJ1 10+ year member]

no...it is a tacoma double cab. Its in a sealed enclosure. Since I am using the sub pre out on the HU...this turns on the crossover on the headunit for the subwoofer. What would the point be of turning the LPF on on the amp itself? Right now I have it on flat "aka full" ....the only thing turned up on the HU is the subwoofer level is at +6. there is no bass boost turned on on the amp or HU itself.....both of those are turned to off. 10 is an older polk EXII....4 ohm with a 150rms

the amp is just a cheap free walmart v3 vra2.0 that a friend gave me. it is 2 channel... 50 rms per channel at 4 ohm ...or bridgeable to 1 4ohm sub (which is what I have done)...but the manual doesnt say what kind of power rating it has when bridged. has the option to bass boost (on or off)...and a crossover (HP / LP with a 50hz - 250hz range)

 

[destined2race 10+ year member]

The point of having the amp on LP is a subwoofer only plays low frequencies. You dont want it on high or full. Thats for if you ran your amp to components or 6x9s or something. Sometimes in trucks you should play with firing the box down, sideways, etc... as the box being so close sometimes it sounds weird. When i had my ranger and my silverado i did the same thing. Try different sides and then mess with the settings on the deck.

Set the the amp to LP, crossover to around 80 htz and then try moving the box around and stuff and see if theres any change. If you cant get any reasonable sound out of it then you may need a new amp with some more power. Just remember a cheap amp, old sub and a sealed enclosure are only gonna do so much even if it is a small cab. Also if you have the know how or can get one cheap you can try a ported enclosure.

 

[93civEJ1 10+ year member]

I am curious why I would want to do that because with the subwoofer preout turned ON on the head unit, it uses the crossover within the HU for the amp. (why i turned amp crossover to full) ...HU crossover for sub is set to 80hz.

Are you sure I would want to turn two crossovers on at both the HU and amp??