Sub amp reaching max gain undistorted

[Big Tex db]

Howdy.  I've recently returned to the car audio hobby. I have some fresh equipment (and some old) that seem to be acting weirdly.

 

2012 F150 4dr 5.0L (Stock - no big three)

AGM battery - One that O'Reillys offers for my pickup (I will return and edit with a brand/specs ASAP)

 

Alpine 172BT (purchased 2019)

1x Skar EVL 12 D2 (New)

Sundown Audio SIA2500 (New)

Wired parallel @ 1ohm

Homemade 2.4cu.ft, 32Hz, L shaped slot port, Sub/Port front facing, ~26 sq.in port area, and appropriate port length calculated from WinISD

--- Previously was using a Memphis Audio 1500.1PRX to drive the woofer

 

 

I'm getting consistent and correct ohm/volt readings thru out the truck and audio system. Headunit is clean at 34/35vol, 40hz -0db SMD tone CD. The only time distortion is showing up during gain tuning is when using the 0db or -5db tones. The -10db and -15db tones show zero distortion all the way to max gain (other than the random blips that show up when turning gain). EQs and Filters are all flat/open/full pass/etc. on the HU and the amp. Sky High Audio bass knob at full tilt. My oscilloscope's readings are consistent with my DD-1's readings.

The reason I purchased the SIA2500 was, one I hear they're a quality brand(and I should be able to run two 2ohm DVC subs @ 2ohm @ 2500watts in future), and two I assumed my 1500.1PRX was on the way out when it was also reaching max gain without distortion when tuning to -10db and -15db tracks.

The sub gets kinda loud, pretty full sound, pretty deep(I keep my SSF around 27-28hz), but at least clean at full tilt on both amps. But after going from 1500watts to 2500watts, I am noticing no change in performance from the sub. No increase in volume, not reaching any deeper with more strength. I've yet to run into this issue with the handful of subs and amps I've used throughout life. I've never reached full gain on any amps in my life yet.

 

If this helps, my Skar 100.4AB (800 watt) 4way is running my door speakers (Skar TX-65s) without distortion. The gains on them are about mid way, more on board with the "usual." I currently have these tuned to the -5db 1k Hz tone. I say this knowing amp/sub components can react differently from unit to unit.


So after burning your eyes out with a wall of text - my goal is to make sure this gain setting will continue to be safe for my equipment BUT MORE IMPORTANTLY I feel I am not getting full performance out of this sub and/or amp(s).

Thanks for your time. I'll reply ASAP

[Joe X]

You don't run a 2500W amp (specially full bridge) on stock electrical, to test this connect a voltage gauge at your amp power terminals, turn up your volume, if you see that voltage drop as you turn the volume up there is for the most part your problem, the other thing is that every 3dB of gain you need twice the power so at 2000W you will be just barely louder than 1000W and to gainthe same 3dB at 2000W you will need 4000W crazy watts, that is why power is not your first option to get loud, cone area is.

[Big Tex db]

11 hours ago, Joe X said:

the other thing is that every 3dB of gain you need twice the power so at 2000W you will be just barely louder than 1000W and to gainthe same 3dB at 2000W you will need 4000W crazy watts, that is why power is not your first option to get loud, cone area is.

 

Understood. Second sub, big 3, bigger alt, and new box supplies getting ordered today.

 

I've read (on F150 forums) that these trucks stock alternators handle 3k watts pretty well.

 

test tone from tone generator app - silent to full tilt

 

30hz 13.04V to 12.86V

40hz 13.04V to 12.9V

50hz 13.04V to 12.2V

60hz 13.04V to 12.25V

 

 

[crispy_chick3n]

yea, that 12.2 makes my eye twitch a little bit. it's my understanding that the SIA amps are supposed to be ok with lower voltage, but that's getting down there. for sure going to need some electrical upgrades. a second battery will get you by in the meantime. 

 

once you get steady voltage I imagine you'll find a clip light with the dd1.

 

for reference, what are your subwoofer and crossover settings look like on the head unit? also how long has it been since you've changed the battery in your dd1?

[crispy_chick3n]

if I remember correctly the SIA is a full bridge amplifier, I don't think the dd1 reads full bridge correctly. something about how the amps work doesn't jive with the dd1. I thought I read something on Facebook about it... idk I could be wrong. now that I'm thinking about it, I don't believe I ever got a clip light when using my dd1 on my SIA3500, although I could for sure hear distortion in the sub

[Big Tex db]

1 hour ago, crispy_chick3n said:

yea, that 12.2 makes my eye twitch a little bit. it's my understanding that the SIA amps are supposed to be ok with lower voltage, but that's getting down there.

 

for reference, what are your subwoofer and crossover settings look like on the head unit? also how long has it been since you've changed the battery in your dd1?

 

Understood, 12.2 getting spicy, definitely below what the truck needs. 

 

When setting gains...HU is full open filters and flat EQ (120Hz LPF..highest setting), SIA2500 has HPF/LPF opened to maximum ranges.

 

After gain is set, HU stays at 120Hz LPF, I tune LPF/HPF on amp with DMM then maybe adjust slightly by ear after that. I never turn up the bass or sub EQs on the HU, only mids/treble sometimes. I never use the Bass Engine on the HU.

 

Battery in DD1 is 4-5 weeks old. I will swap a fresh one in and test.

 

1 hour ago, crispy_chick3n said:

if I remember correctly the SIA is a full bridge amplifier, I don't think the dd1 reads full bridge correctly. something about how the amps work doesn't jive with the dd1.

 

I'll Google up on this and see what I can learn. I have a cheap ($80) Oscilloscope/DMM combo. I understand the limitations the small display has for projecting waves in detail.

 

Also crispy, thank you all the helpful posts you make on here. I've learned a quite a bit from reading replies from you and the other bassheads around here. Cheers

[Big Tex db]

2 hours ago, crispy_chick3n said:

idk I could be wrong. now that I'm thinking about it, I don't believe I ever got a clip light when using my dd1 on my SIA3500, although I could for sure hear distortion in the sub

 

After thinking on this, I am having zero audible distortion (nor when I was viewing the Oscope during play..again for what its worth with a cheap tool). 

I actually tested the Sub EQ setting on my HU just now. 40Hz -15db track from SMD's CD, everything wide open/flat, bass knob to max, I did not set off the DD1 until 14 of 15 Sub EQ setting was reached. I didn't try listening to this though, just seems absurd.

[Joe X]

9 hours ago, Big Tex db said:

 

Understood. Second sub, big 3, bigger alt, and new box supplies getting ordered today.

 

I've read (on F150 forums) that these trucks stock alternators handle 3k watts pretty well.

 

test tone from tone generator app - silent to full tilt

 

30hz 13.04V to 12.86V

40hz 13.04V to 12.9V

50hz 13.04V to 12.2V

60hz 13.04V to 12.25V

 

 

 In any case they specify rated power @ 14.4V so your amp is not sourcing anywhere near rated power.

 

Edited June 6 by Joe X

[Big Tex db]

6 minutes ago, Joe X said:

 

Those readings are obtained with the engine on?

 

Yes. And I think I see where that question is leading to. Going to go double check a couple things real quick.

[Joe X]

3 minutes ago, Big Tex db said:

 

Yes. And I think I see where that question is leading to. Going to go double check a couple things real quick.

 

That a very low voltage with your alt running, if you rev up the engine and you still see 13V or so then you are almost not charging the battery, resting voltage usually is 12.5 - 12.8V and the alt should be sourcing the 14.4 or so.