# Protection mode on heavy bass



## Weffy (Feb 1, 2010)

Okay, I just finished up my new system and before anything heres some specs:

Stock alternator and battery
2 gauge from alternator to battery+
4 gauge from chassis to battery-
*did not remove stock cables, not sure if it matters.
2 4gauge wires from battery to d-block in trunk.
4 gauge from d-block to amps.
4 gauge grounds.

AMPS
Boss D800.2 on 2 American Bass XO 15"
Sub box terminals read 7.5ohms each and are both wired to the bridged amp in parallel.

Sundown SAX100.4 on American Bass 5.2's up front and Kicker KS600 in back

I don't know if anyone remembers the 'you gotta start somewhere' thread I had with a hack-job fire hazard setup, but this one is mostly right.

PROBLEM
Whenever I hit a heavy bass note the Boss amp kicks into protection mode for 2-3 seconds, then back on, then into protect mode. It was doing this with the sub at +3dB, but I then ran the 2g alternator wire, and 4g ground on the battery and now does this at +7dB.(gain is set low on amp for SQ I guess, but sometimes you just need to bump)

At idle, the voltage at the amp sat at 13.65v and dropped to 12.8v at +0dB before upgrades, and now sits at 14.3v and drops to 13.6v at +0db. On the same song/bass note.

The voltage between the ground terminal on the amp and a stock ground bolt in the wheel well is about 4mV. I understand that anything over 10mV suggests a bad ground.

All of the above "tests" were done either with no music, or with the volume set to 25.

I've come to the conclusion that either the alternator can't make the power, or the Boss amp is just a POS.


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## Oliver (Jun 25, 2007)

Get one of the* Sundown class D amps* 

Might want to make sure that the *size of wire going to the amp for power* is the *same size as the ground wire* or return leg , drain wire , etc..,


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## chad (Jun 30, 2005)

the question is how the ground performs under load.


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## Oliver (Jun 25, 2007)

My thoughts are if you are filling a pool with two hoses and draining it with one hose . . . there should be a backup.

more in than going out.


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## Weffy (Feb 1, 2010)

Okay, is there a way to test the ground, or can I only make a new connection and be sure it is the best possible?


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## kyheng (Jan 31, 2007)

Wire them at higher impedence should help. Number means nothing if you keep on getting protection mode.


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## Weffy (Feb 1, 2010)

I moved the battery into the trunk today hoping that it would help the problem a little.

This accomplished nothing except now I have a heavy alternator whine, but the voltage at the amps is now a proper 14.5v at idle. 13.6v before it cuts out.

I was talking to the shop that sold me the amp, and they said that the Boss D series are bad for this problem?? and the only way to remedy it is to set the input sensitivity to 200mV-2V(crank the gains) OR buy a better amp.
The latter makes sense, as it seems that the magic number for this amp is 13.6v and its teetering on protection.

I'm done with this until I get a non-sucky amp, but does anyone have any advice for the alternator whine? Maybe run a dedicated ground wire to the battery in the trunk for the radio?


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## chad (Jun 30, 2005)

It's 13.6 AT THE AMP when it cuts out? If this is the case I'm wondering if the amp is not protecting itself from over-current..... Bridging may not be the way to go as suggested earlier.


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## Weffy (Feb 1, 2010)

yes, right now the amp goes into protection mode when the DMM reads between 13.3-13.7v, then while its in protection it reads 14.0v, then when the amp kicks back on for half a second it shoots down to 13.6-ish then cuts out.

I even just wired a temporary in-dash volt gauge to the amp just to be sure the DMM isn't too slow. Results in a few, need to go to my special parking lot, even though it will most likely be the same results.

On paper, the amp claims to be bridgeable at 4ohms, putting out 1600 max, It does not state RMS at bridged, but only 260w rms x2 at 4ohms.

Oh, and the alternator whine was fixed by repositioning the RCA's away from the battery (duh)


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## chad (Jun 30, 2005)

A speaker is not a constant load, that's why it's called impedance, it's derived from many variables, it and will drop below the rated NOMINAL impedance. Since a bridged amp sees half of the normal impedance per channel it's quite possible said amp is seeing one-point-something ohms per channel.

That being said it sounds like you have done a good job troubleshooting voltage issues, well done! Unfortunately it does not sound like a voltage issue but rather the amp protecting itself from too low of an impedance.


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## Weffy (Feb 1, 2010)

I guess I'll just need a bigger amp. Can't go wrong with more power, so I'm told.

If the amp is protecting from low impedance, wiring to 2x2ohms wouldn't help, and 2x8ohms wouldn't make the SPL I'm trying to get from this thing.


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## 60ndown (Feb 8, 2007)

dual 4 ohm subs x 2 = 4 coils all with 4 ohms,

how are your subs wired? what ohms does the amp see?

is it worth trying to wire them to show the amp an easier load?

max volume wont be louder *ideally* but wired at 4 ohms (8+8) it might be louder then when it cuts out presently?

maybe even run all day?


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## chad (Jun 30, 2005)

60ndown said:


> is it worth trying to wire them to show the amp an easier load?


Totally worth it but people obsess over numbers... I'm beginning to like the Zuki approach 

also (not you luke) remember that just because an amp is larger means that it handles lower impedance better, in fact sometimes it's quite the opposite due to higher voltages on the rails.


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