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amplifier's protect mode

22229 Views 65 Replies 5 Participants Last post by  lcurle
alright so ill keep it simple, heres my issue. but firstly, my gear:

2 Directed Electronics 23124. 12" subs 750 watts peak each
Crunch BLX1000d amp
8 ga amp kit
Sony CDX M620 headunit

Ive had my subs/amp for about 3 weeks, and they were working fine, damn they pump hard. But now, just today, the amp went into protect mode, and continues to do so. trends:

-my car is not hot, neither is my amp, nor subs. so no overheating, im assuming
-my amp is screwed onto the back of my sub box with my backseat dropped. so, in other words, good venting.
-the music isnt that loud, especially compared to past playing before the problem came up.
-it has happened at low volumes
-the very last occasion that the amp cut, protect mode DID NOT come on. the bass just stopped for a few seconds, i lowered my headunit volume, and the bass popped back on. repeat, did not go into protect mode because light was still green.

sorry for the big wall of text, just really hoping its something simple like grounding, and not my amp itself.

as far as grounding, the ground wire is attached to a bolt underneath my rear speaker deck. I did not install the amp myself so i dont know if they sanded the surface but the grounding looks alright to *me*.

haaaalp :p
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also, my gain is at 75%. seems worth mentioning.
Try turning the gain down a bit. 75% sounds very high.

Sometimes deep bass can trigger amp protect mode. Happens on my amp a LOT. I think its my setup, as can listen to say pendulum for about 5minutes, loud as I can go, without distortion and the amp does turn off.
Im gonna be honest, I had it even higher than 75% before this happened, and the bass was REALLY knockin, and it never turned off. Like I said, this just happened, and it has happened at low volumes.
maybe your amp can't handle the load? this happens to me too because mine is a 2 ohm load and my amp is stable to 4 ohm, so when it get's too loud the amp shuts off until you reset the deck or restart the car.
would the ohm problem start immediately? Ive had the subs for 3 weeks, and they've kicked major ***. they are awesome, seriously. the amp is crazy powerful, but then this happened.i figured that if it was an ohm problem then they wouldnt have worked to begin with.

i took it to a local customs shop (where it was "professionally installed") and they said theres little chance its the grounding because he made sure it was great. but we'll see this upcoming TUESDAY (which is ********). I told them ill keep them updated on the situation. My only guess was grounding, and they shot it down. And the ohm problem doesnt make sense to me, because Im not familiar with car audio all that much.

it still turns off after about 15 minutes of playing at a low-decent volume.
Can you tell us where its grounded and the condition of the ground? Is it bare metal and not covered with paint?
Can you get us a picture?

Have you set you amp up correctly for the sub?

This is done by:
Turning volume on headunit up to 3/4.
Then adjusting the levels on the amp until the sub just starts to distort. (you can usually tell). Once its started to distort, turn it back 1/8-1/4 turn for the optimum sound.

If its turning off after 15minutes, then my guess is overheating. This is caused by the gain (bass boost or whatever you want to call it) is set too high.
Yeah its tuned for the subs correctly (well I assume. they installed it and said I was "good to go". ill know on tuesday when I have to go back...). and Ive felt the amp when it shuts off, its not hot to the touch. Its either warm or even a bit cool.

I can get a better picture of grounding, but heres a quick one. this is underneath my rear deck (i had to lift up the carpet with one hand, and take the pic with the other). Sorry a little blurry
sorry didnt see the link was broke


my car is silver by the way, so the blackish metal im guessing is paint-free. pretty sure it is. shrugs
my friend thinks its because of the ohm load from the subs to the amp not matching, but ill let them (installers) decide. but that still seems like a problem that would have come up sooner. im still hanging onto the grounding.
Hmm, how are the subs wired up? Are they bridged?

Just had a look at spec of amp and i understand this in a monoblock amp?
Hmm, how are the subs wired up? Are they bridged?

Just had a look at spec of amp and i understand this in a monoblock amp?
I dont know how to name it, but the subs wiring go into 2 positive terminals on the amp, no negative terminals. i found that odd.

from the amp its wired directly to the box terminals.

forgive my ignorance, im familiar with home theatre quite well, but new to car audio. I have a few pics if it helps. just let me know and ill upload em.

no clue about the monoblock thing... sorry :(

edit: the specs just to clarify, and confirm for yourself...hope this helps

# 750 Watts
# BlackMaxx Flo-Thru Heat Sink Design
# PWM Mosfet Power Supply
# Fully Bridgeable Design
# Black High Quality PCB Design
# High Speed Mosfet Output Devices
# Class AB Operation
# Separate Bass and Treble Controls with Switch
# HP (High Pass) from 60 Hz to 1.2 kHz Adjustable Crossover Network
# LP (Low Pass) from 40 Hz to 150 Hz Adjustable Crossover Network
# HP/LP/Flat Select Switch
# Silver RCA Line Input , High Level Inputs
# Silver RCA Line Output for Amplifier Daisy Chaining
# Internal Protection Circuitry
# Green "On"LED, Red "Protect"LED
# Mono Channel


# 1 x 350 Watts @ 4 Ohms
# 1 x 750 Watts @ 2 Ohms
# 1 x 1000 Watts @ 1 Ohm
# Size (WxHxL): 10.1" x 1.85" x 12.79"
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it shoudnt be grounding..that doesnt rly make sense if its grounded in a good spot that works...i had a grounding problem before and the subs didnt work at all cuz it wasnt touching the metal...and are your subs DVC or SVC? and how much ohms are they? and how much ohms is your amp stable to? if its 4 ohm DVC you can wire it in paralell. positive terminal and negative terminal from both subs to the same positive and negative on the amp. so it will be like both positives in same terminal on amp and both negatives on same terminal on amp. thats a 2 ohm load. if your amp is stable to something higher than that,,, it WILL trip out cuz it cant handle it, if its stable to 2 ohm, you'll get full power , if its stable to a lower ohm, then it wont trip out but you wont get full power,, which isnt a problem unless you want more power.
thanks for the replies guys, this troubleshooting is quite helpful for me. really.

alright so, ill throw grounding out for now, and assume its an ohm load problem. firstly, is it unsafe to play music (not too loud) in the mean time before it gets fixed by the installer? I dont want to blow anything.

secondly, i already asked but i didnt see an answer i dont think. if it was an ohm load problem, would it not strike a problem earlier than 3 weeks or so? Like i said this is the first few days Ive had the problem. the previous weeks were flawless.
first time i wired mine to 2 ohm load it was fine for a while then started tripping out,, maybe its not an ohm problem tho?:p but maybe it is, who knows, im just assuming... and no nothing should get damaged while playing your music loud if its the ohm load...the amp cuts of to protect itself, thats all,,, just restart your deck and it shud be back on,, thats what im doing until i get a new amp.
Can you get a pic of the wiring?

I dont thinl 2 subs would run effectively off 1 channel.
in my opinon , two subs sound like **** if they're on there own channels:p(ex. two channel amp) if the amps bridgeable or sumthing you shud wire both subs to the same terminals to bridge the amp...more power and sounds better, only problem is if your amp isnt stable to it:( like mine:(:(
His amp is mono,, so there shud only be two terminals, 1 pos. and 1 neg. and both neg. wires shud go to the neg. on amp and both pos. wires shud go to pos. terminal on amp, some mono amps have two neg. beside eachother and two pos. beside eachother,, but you wire it the same i guess,, neg. to neg. and pos. to pos. :)

EDIT: how come you wrote 750 watts for the amp,, but at the bottom in the specifications, it says if the amplifier sees a 1 ohm load, its 1000 watts? or is 750 watts per sub? i need an amp liek yours:p 1000watts rms at 1ohm load.:p
I can get pics but my phone isnt very good in dark areas (tinted windows and horrible whether)

heres a closeup of my amp terminals. my wires coming from one of my subs goes into a positive terminal on the top, and the other sub's wires connect to a negative terminal way on the bottom. seen here (pixelated badly)

like this:
+ wiring to sub1
- no wires
+ no wires
- wiring to sub2

and heres a bit of a zoomed back pic, hopefully you can pic out a few things.
a bit messy at the moment haha.

the wire that goes up under my deck's carpeting is the grounding, which connects to that bolt in the previous picture.

god, horrid quality for sure, but i try. hopefully you can make some stuff out.
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lol the wiring looks exactly like my amps and subs:p except my amp is 2 channel and it looks exactly like that wen its bridged

Find out what your subs are ,, like the ohm and voice coil of them, then find out how much ohm your amp is stable to, then you can re-wire your system if YOU want to.
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