# My sub cuts out...



## VDub2625 (Jan 4, 2003)

...if I have it play semi-loud for more then 10 minutes or so. Cuts out as in does not make noise again, for the duration of the ride. The power light is still on on my amp's remote bass control,however.
The amp is more then capable of handling the power (RF Punch 20th anniv., it has something like 700wRMS capacity), and the sub is capable too (a/d/s 600-something). I've also been very careful to match them, I did the whole "measure the voltage with a DMM and calculate the wattage" etc. 
So, why, after it's been working for several months, does it do this? It seems to happen when the amp warms up a little, and returns to normal after being off for a while. I'm guessing a loose component, but could this have been caused by the way it's used? And how would I go about fixing it?


_Modified by VDub2625 at 6:03 PM 11-12-2009_


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## wishuhadmyvw (Jan 7, 2006)

*Re: My sub cuts out... (VDub2625)*


_Quote, originally posted by *VDub2625* »_...if I have it play semi-loud for more then 10 minutes or so. Cuts out as in does not make noise again, for the duration of the ride. The power light is still on on my amp's remote bass control,however.
The amp is more then capable of handling the power (RF Punch 20th anniv., it has something like 700wRMS capacity), and the sub is capable too (a/d/s 600-something). I've also been very careful to match them, I did the whole "measure the voltage with a DMM and calculate the wattage" etc. 
So, why, after it's been working for several months, does it do this? It seems to happen when the amp warms up a little, and returns to normal after being off for a while. I'm guessing a loose component, but could this have been caused by the way it's used? And how would I go about fixing it?

_Modified by VDub2625 at 6:03 PM 11-12-2009_

what ohm load are you at?


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## VDub2625 (Jan 4, 2003)

*FV-QR*

I'd have to double-check, but IIRC the sub is a 2ohm. I actually couldn't get any specs on the sub 9since it's so old), so I had to rely on the guy who sold it to me (he is on here, apparently a reputable guy so I wasn't worried







).


_Modified by VDub2625 at 8:44 AM 12-3-2009_


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## Pat @ Pitt Soundworks (Nov 14, 2008)

*FV-QR*

How is your gain set? Bass boost? Sub level on the head unit? Crossover?


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## VDub2625 (Jan 4, 2003)

*FV-QR*

Sorry, shoulda specified. 
From memory (I can get the full details tomorrow):
head unit has +8 (of 15) on the sub out usually.
Bass boost on the remote is generally set between half and 3/4 full. I don't think it's ever been on full (except to test when it goes bad). 
Gain is set as per the sub's specs, i can get an exact setting for you tomorrow as well as the low pass filter 9I think it's under 100).


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## VDub2625 (Jan 4, 2003)

*FV-QR*

Ok, update... on the drive home, it cut out again after a few minutes (quicker then usual but i was listening to loud music)... then after a hard turn, it came back. Dunno if it was the shock of the turn or if it cooled down enough to work again, but it's something...


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## ShaggysGTI (May 15, 2009)

When the amp cuts out, see if it has gone into protect mode.


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## VDub2625 (Jan 4, 2003)

*FV-QR*


_Quote, originally posted by *ShaggysGTI* »_When the amp cuts out, see if it has gone into protect mode.


How do i tell? The power light stays on as if everything's normal.


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## blazerpounds (Mar 19, 2008)

check your wiring.
Check sub impedance with a digital multimeter.
Turn down the bass boost.
Get more subs if you want more bass.


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## ShaggysGTI (May 15, 2009)

Most amps have a protection mode, and a light indicating so. If it overheats, it turns off till it gets to a better temperature range.


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## VDub2625 (Jan 4, 2003)

*FV-QR*

But it's barely warm to the touch, and it's laying flat. The front speaker amp gets warmer and it's fine.
It could be the wiring but the on light is on, even when there's no sound, so I'm sure my wiring is ok. I know I know, double check, but it's still doubtful.
The amp has been operating at the current level of boost for several months, and has never cut out before. i was assured this combo of amp and sub would be a good match for some respectable sound.


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## ShaggysGTI (May 15, 2009)

Maybe a coil is damaged on your sub, or maybe the wiring inside of your box came off a terminal? I'd pull the box out, and pull the subs out of the box, and test the impedance of the coils.


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## VDub2625 (Jan 4, 2003)

*FV-QR*

Thanks, I'll try that http://****************.com/smile/emthup.gif


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## VDub2625 (Jan 4, 2003)

*FV-QR*

Ok, I pulled the sub out, and this is what i saw...
The POSITIVE terminal on the wiring connector was wired to the sub's dual voice coil NEGATIVES. And the coils are wired in parallel (pos to pos, neg to neg). 
The back of the sub said this:
"Dual 4 ohm voice coil, recommended RMS Power 40-300w each coil". I did the DMM thing setting the amp for 600w (bridged as 2ohm). it's a 2 way amp, and I have them hooked up to each other (like the amp says, pos to pos on one side, neg to neg on the other side, it automatically bridges). 
Does this sound right so far? Except for the fact that it seems my sub was hooked up backwards, the rest seems cool. Is it a good idea to have both coils bridged and the sub outputs bridged? Or would it be a better option to run each coil on each output of the amp? The way it is sounds good to me, but the other idea popped into my head.
I checked each coil with an ohmmeter and i got 3.something, which leads me to believe the coils are good.


_Modified by VDub2625 at 12:52 PM 11-20-2009_


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## VDub2625 (Jan 4, 2003)

*FV-BumpIt(1258788254709)*

Bump again. Would a cap be a good idea to put into the system as well? I've noticed my voltage gauge can bounce with the sound if it's turned loud.


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## Hard_Timez (Dec 4, 2004)

*Re: FV-BumpIt(1258788254709) (VDub2625)*

peopel are going to hate on this but i use a cap. it seems people either love it or hate. the true audiophiles don't like them. mine works, never dimmed a light since. but on this install, i did "over-ground" things, just to be safe. btw, i got a 10 farad tsunami one from the local car audio shop with a slight scratch for only 100 bones. too good to pass up.


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## VDub2625 (Jan 4, 2003)

*FV-QR*

So which is better?








or


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## Non_Affiliated (Feb 12, 2002)

*Re: FV-QR (VDub2625)*

Model Number of Sub-woofer and amp please?


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## VDub2625 (Jan 4, 2003)

*FV-QR*

Subwoofer is an a/d/s 612rs.2, amp is a Rockford Fosgate Punch 150.


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## harmankardon35 (Sep 16, 2009)

*Re: FV-QR (VDub2625)*

sounds like you have a stereo amp bridged to a 2 ohm load.this will cause it to cut out and go into protect mode A Dual 4 ohm sub can be wired as either 8 ohm or 2 ohms. Most class a/b stereo amps are 4 ohms minimum bridged, 2 ohms minimum stereo. In that pic you posted, the first one will be your best wiring option. It will run each coil on a different channel. The drawback to this is you will likely need another wire running into the box (and another input terminal) for each coil.... If that's the case and you dont want to do it, you can wire the sub in series like in this pic below.
This method of wiring will give you 8 ohms to bridge your amp to (and allow you to use only one terminal on the sub box, as opposed to 2)


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## VDub2625 (Jan 4, 2003)

*FV-QR*

Ok, thanks. So the dual coils wired seperately to each output is perferred, but series is an option too. Good to know, thanks. And of course I'll have to re-set the gain output.


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## Non_Affiliated (Feb 12, 2002)

*Re: FV-QR (VDub2625)*

HK is right I missed a few things in the thread about DVC 4 Ohms, and the 25 to life Punch 150 specs. (Assuming that was the amp you have)
4 Load Per Channel 75 Watts x 2
2 Load Per Channel 90 Watts x 2
4 Load Bridged (Mono) 180 Watts x 1.
So Yeah running 2 Ohm mono is what is making it cut out. The only issue is if you run it 8 Ohms mono, you going to b running at about 90 Watts to the sub. Which may or may not allow the speaker to reach it's full potential depending on what box design you have.


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## VDub2625 (Jan 4, 2003)

*FV-QR*

The amp is rated at the exact same specs the old Punches were. It really puts out around 10x that amount








Interesting, since the box was wired by a certian professional from around here and I was told all i had to do was plug & play...
Thanks guys! I'm just going to leave it unplugged for now until I get a chance to re-set the gains and wiring properly http://****************.com/smile/emthup.gif


_Modified by VDub2625 at 3:41 PM 11-26-2009_


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## harmankardon35 (Sep 16, 2009)

to the OP...there is no benefit to choosing either wiring option. Weather you run each coil seperate or bridge to 8 ohms you will end up with the same power output from the amp (which if the specs non_affiliated posted are correct, will be 150 watts RMS total to the sub) Given this, i would simply wire it like in the diagram i posted, bridged to 8 ohms. If you want full power from your amp, then you will need either get a different sub that can be wired to 4 ohms bridged, or get another identical sub and run two of them








with ohms, its either double or half the coil rating when dealing with DVC.

_Modified by harmankardon35 at 4:48 PM 11-26-2009_


_Modified by harmankardon35 at 4:48 PM 11-26-2009_


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## VDub2625 (Jan 4, 2003)

*FV-QR*

Ok, thanks. I think i'll do as you said simply becuase it means i can just keep the two wires going into the box. 8ohm isn't going to stress out the amp, is it? Do i have to be extra careful of higher levels?
Trust me, I wish I could get a second, I think it would help... but finding another one of these would be a mission, haha


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## harmankardon35 (Sep 16, 2009)

no 8 ohm means less resistance than 4 or 2 ohm, so its actually easier on your amp....but you get less total power output (but with less distortion!!)


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## VDub2625 (Jan 4, 2003)

*Re: (harmankardon35)*

So here's a final question(s)...
knowing that this was wired wrong the whole time... and it didn't do it at first, but only recently started cutting out. Have I damaged/shortened the life of my amp or sub? SHould it perform fine from now on or should I expect problems?
Oh and I can assume this but I figured I'd put it out there... to calculate the power I'd want to get, using the 8ohm load bridged over 2 channels, it'll be acting like a 4ohm load on each channel?
The sub takes 600wRMS at 4ohms bridged (acting as 2ohm). It says 300wRMS max each coil, so does that mean I calculate for 600w? At 4ohms since that's what each channel is seeing?
In that case:
sqrt(600*4)=49v. Right now it's set for 34v (sqrt[600*2], which made sense before when it was in parallel).
It is actually going to be putting out MORE power? is this right?


_Modified by VDub2625 at 9:05 AM 12-3-2009_


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## Non_Affiliated (Feb 12, 2002)

*Re: (harmankardon35)*


_Quote, originally posted by *harmankardon35* »_no 8 ohm means *more (higher)* resistance than 4 or 2 ohm, so its actually easier on your amp....but you get less total power output (but with less distortion!!)

Fixed.


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## harmankardon35 (Sep 16, 2009)

*Re: (Non_Affiliated)*


_Quote, originally posted by *Non_Affiliated* »_
Fixed.











haha, thanks








Vdub the protect mode is there for that exact reason, to keep from burning out electronics inside the amp. No i would not expect future problems. (but anything is possible)
and yes bridging to an 8 ohm load would see each channel at 4 ohms in terms of power output, just like bridging to 4 ohms would be the same as each channel being run at 2 ohms in terms of output power..


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## VDub2625 (Jan 4, 2003)

*FV-QR*

Thanks. i feel mighty stupid since I was in a voke school for electronics, and it all comes back to me the more I read... but it's way too easy to trip yourself up with all this so I like to verify just in case








I left it at the lower gain output for now (it's at 34v, supposed to be around 70v). We'll see how it holds up coming home from work...


_Modified by VDub2625 at 8:50 PM 12-3-2009_


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## BassNotes (Mar 16, 2005)

*Re: (harmankardon35)*


_Quote, originally posted by *harmankardon35* »_no 8 ohm means less resistance than 4 or 2 ohm, so its actually easier on your amp....but you get less total power output (but with less distortion!!)

8 ohms is MORE resistance than 4 or 2 ohms. Higher load impedances are easier on the amp because they draw _less _current from the amp for a given output voltage. Lower current, though, also means less power put into the loudspeaker(s).


_Modified by BassNotes at 4:25 PM 12-3-2009_


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## VDub2625 (Jan 4, 2003)

*FV-QR*

I've been driving myself crazy with numbers... someone back me up on this...
The sub is a dual 4 ohm, 300w each coil. Thus in series it would be able to handle 600w? And it would present an 8ohm load.
If I wanted my amp to put out 600w at 8 ohms, I'd do this:
sqrt(600w*8ohm)=~70v on a DMM (at 50hz test tone, 3/4 full volume). 
Is this correct? Sorry for the repetitive questions... i just like to make sure my stuff is safe...
EDIT: found on the web that in series, the amp power rating is double any one speakers, thus 600w...


_Modified by VDub2625 at 8:49 PM 12-3-2009_


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## harmankardon35 (Sep 16, 2009)

i think you are defiantly confusing yourself there. 1. your amp is absolutely safe being bridged to 8 ohms. Higher ohms = more resistance which will demand less from the amplifier. Ideally, to get full power you could bridge to 4 ohms, but thats impossible with a DVC 4 ohm sub (like I said, you can only wire it to 2 or 8 ohms) 2 ohm is too low for an amp to be stable bridged, that is why your amp was cutting out (less resistance = more current demand from the amp) Your sub will be able to handle 600 watts total regardless id its wired in series or parallel. But with your set up, the only safe way to run your amp is bridged to 8 ohms, which is perfectly safe, but you are not going to see maximum output from your amp (but still not bad)

_Modified by harmankardon35 at 10:33 PM 12-3-2009_


_Modified by harmankardon35 at 10:36 PM 12-3-2009_


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## VDub2625 (Jan 4, 2003)

*FV-QR*

I don't mind not being able to see full power from my amp, as long as I can see full power that my sub can handle







I am confusing myself, you're right haha. thanks for the info guys! It didn't cut out and sounded good all night last night


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## VDub2625 (Jan 4, 2003)

*FV-BumpIt(1259955161745)*

Ok, it sounds much louder then it did before, and I don't even need bass boost!








The meter (set to ACV, 50hz sine wave at 3/4 full volume) said I was getting 62v out of the amp at max gain. This is about 960w at 4ohm, or 480w at 8 ohm. This is what you guys must have meant by half power at 8ohm







so to keep theamp safe I set it as if the speaker load was 4ohm (to 48v), and it's still nice and loud!


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## VDub2625 (Jan 4, 2003)

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Crap... still having problems... it's 50/50 if it'll be on when I start the car... and tonight on the way home from work it stopped working again. (I haven't been able to drive the car for a few days due to other workings-on so I haven't been able to really test it). 
Could the amp itself be damaged?


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## Non_Affiliated (Feb 12, 2002)

*Re: FV-QR (VDub2625)*

Possible.


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## VDub2625 (Jan 4, 2003)

*FV-QR*

I tried lowering the gain to see if that helped the cutting off, and it did... it lasted a little longer before being cut off, and then it came back in less time. 
So now it dosen't seem to want to work... ever. It doesn't have any output at all, even when you first turn it on, but the power light is on. 
If it's broken what can I do? Is my only option replacement? is there a way to test it?


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## BassNotes (Mar 16, 2005)

The amp probably has a thermal shutdown circuit to protect itself from overheating, right? Does that appear to be what's happening?


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## VDub2625 (Jan 4, 2003)

*FV-QR*

That does seem right. The sub was hooked up as 2 ohm even though the manual states not to hook it up that way. So it overheated repeatedly and cut out. Now becuase it happened so many times I can only assume it hurt the amp's abilities and causes a thermal shutdown when even the littlest power goes through.


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## Non_Affiliated (Feb 12, 2002)

*Re: FV-QR (VDub2625)*


_Quote, originally posted by *VDub2625* »_That does seem right. The sub was hooked up as 2 ohm even though the manual states not to hook it up that way. So it overheated repeatedly and cut out. Now becuase it happened so many times I can only assume it hurt the amp's abilities and causes a thermal shutdown when even the littlest power goes through.

So were you running it 2 Ohms mono and it is a 4 Ohm mono amp? You most likely have killed the amp if that's the case.


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## VDub2625 (Jan 4, 2003)

*FV-QR*

Damn.







Now the question of what to do... i bought this setup from a forum member who had did all the wiring and told me it was just a drop-in setup. Seems he might have miswired it.


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