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Sundown Audio

Sub amp tuning, and pulling my hair out...


RobertK

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So...  To start, I'm broke.  My system is small, cheap, but I tried to check reviews and dyno tests before buying equipment.

2007 Silverado classic crew cab.  I want subs to fit behind rear seat, so very shallow subs and boxes.

Sony "1000" watt max 12" sub (prob 250 rms) and sound stream 13.3 500w max, 200rms sub, both 4 ohm, paralleled.  sealed boxes, I like tight bass anyway, besides behind rear seats.

Amp is a B&B 2000.  Rated at 900watts at 2 ohms.

 

Today, I played test tones, (25 to 80, 5hz steps) listened and watched ac voltage at speaker terminals.  initially, I set the sub sonic at 35ish, and tried to use bass boost and bass boost freq to even out the voltage across 40 to 80hz.   When that was done, I played 50hz, and set gain to 900watts.  (900 x 2 ohms=1800, square root of 1800 is 42.43 volts.)  (Head unit was set to 32 out of 40, 95% sure no distortion.)

Front 6.5 polk audio separates and tweeters, 100 rms, 300 max.  Running 250 watts per side, they sound pretty happy.  Some recordings may be a little too high at 250 watts, most are fine.

 

 

Anyway....  Turn usb thumb drive on, start picking songs I know that have decent tight bass.  Bass sound good, but low.  Barely mixing in with fronts at 22 volume, mostly blah at 32 volume.  Tight bass, but unimpressive.  I had better bass setting the amp by ear.  Formula says 900 watts at 32 volume.  2 - 12's with 250ish rms each should do ok at 500 watts,  be over driven at 900 watts.  What gives? 

So... Turn fronts and rears down to 1/4 rca output, left the subs full rca level out.  (Should still be 900 watts at 32 volume.)  Play AC/DC first, repeat 4 or 5 times, then Jackyl 4 or 5 times.  Slowly adjusted sub sonic till sounded better.  Slowly upped bass boost freq and level till it hit like I thought it should.  Turned mids and highs back up.

Sounds pretty good, except on some songs, I can only turn pac-1 (just a rca level control) on bass amp maybe a 1\4 way up before sounding like I'm overdriving the poor subs.  Other songs, (Prince, Steely Dan...) I can turn pac-1 90% and sound pretty good.

If I pick one of the songs that sounds like it will overdrive the subs and set the gain to 900 watts, the bass goes down a fair amount, and the other songs then go back to ho-hum bass. 

 

I'm just frustrated.  Pick the right song, and the truck is loud and clear enough to never need another system.  Roll down the windows on the expressway, and still be plenty loud.  Pick the wrong song, and I have too much yucky bass, or barely enough bass to fill in with the highs.  Granted, sound quality and record quality of songs, but still.  Having to play with the pac-1 on every song is both a blessing and a pain in the ass, and I'm afraid to put the meter back on the bass amp to see if and how much I'm overdriving the cheap subs.

 

So... Any tuning suggestions that might level out the bass a little better, but keep it able to stay on the 900 watts target?  The bass amp is rated at 900 watts RMS at 2 ohms.  I can't imagine its putting out much more than that.  I just want hard, solid bass, not the rap stuff, and not have to have that extreme range on the pac-1.  (sometimes overdrive subs at 10%, to barely mix in bass at 90%)  I do have to run bigger wire to the amps, but so far, they are dealing with the 4 and 8 gauge runs.  If I ever get off my ass, I have 0 gauge welding wire to run to the amps, then a 0 to (dual) 4 gauge splitter to go to the amps. 

 

Sorry for the long read.  Just trying to give as much details as I can.

 

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