fiXXXerMet

I have had my stereo installed for a while now and have been putting up with this issue, but am pretty fed up and could use some help!

Basically, my subs usually (not always) cut off unless the volume is pretty high. So if I am listening to something quiet, the bass doesn't kick in until I turn the volume way up.

Another interesting note is that if I turn the voltage (gain?) on the subwoofer down, this issue happens less (though the bass is also not as powerful).

Does this issue call for some kind of voltage regulator or stabilizer device?

MP3Car.com

 

trader007

sounds like this could be another 10 page long problem. sounds very weird.

youll have to start by listing what parts you have (including model numbers if you can) and what order they are connected. we need an idea of what you have before we can suggest anything.

fiXXXerMet

Here's what I have:

• 2x Alpine Type R 12" (2Ω + 2Ω) SWR-1222D Subwoofers
• 1x Alpine MRD-M1005 Amplifier
• 2 farad capacitor
• Pioneer DEH-P6800MP Head Unit
• All 2AWG Wiring

I believe that the subs are wired like http://akamaipix.crutchfield.com/ca/...2-ohm_mono.jpg but will take the box apart after work to double check.

Thanks!

trader007

yeah i think thats right. you can unhook the subs from the amp and test the wires with an ohm meter- you should get 2ohm for the pair, or 4ohm each speaker. this is a good idea to test because it will rule out the subs causing the problem.

otherwise, if the subs are proper, then i have a bad intuition your alpine amplifier is on the fritz. it sounds very much like a broken amp, from what you describe. to test, i would try hooking an ipod directly to the amp and see if the subs work properly.

btw- very nice choices on your components. alpine and pioneer are tops.

fiXXXerMet

Yup, they're wired at 2ohm (multimeter read 2.1).

I will hook my MP3 player up directly and see what kind of results I get from that...

I always had a feeling that 'the head unit wasn't putting out enough voltage' while the volume was low, but was when the volume was high. Could such a thing happen / make sense?

And thanks! I got my equipment from a pawn shop at an awesome price, and had the box custom made to fix the specifications from the subs. My next system will likely be alpine all the way.

trader007

actually, i have never seen a headunit act like that on the rca preouts. its always an amplifier problem. just a few months ago- i gave my buddy an amp that he just cooked like a fried chicken, and it still works but when he has to turn up the volume quite a bit or else the amplifier just wobbles the sub really weird. he cant listen to the radio with the sub on at low volumes anymore.

also, the receiver out in my garage does a similar thing. only the left side works, but when i crank up the volume a little the right side kicks in.

not saying im sure thats your problem, but all fingers are pointing at the amp.

soundman98

trader007-- alpine and pioneer are top of the most common names in audio, not the best, but no-where near the worst...

it sounds like it might be a amp problem--- also, another thing you could try is to change the rca cable(or just run one on the outside of the car for testing)-- it is possible that it is pinched/broken to the point that a lower level signal can't jump the break, or is being shorted.

trader007

well thats what i meant. of course there is custom and niche brands that can easily make a high quality product for outrageous prices...

tell you what though, i have a late-model kenwood 4ch amp that is also incredibly good for what you pay. very, VERY rugged and super clean sound.

MP3Car.com

 

Phoenix750

OP, do you have another amp you could use to test this with? I agree that it might be the amp's fault.

In the past, I had the same sort of issue, but my solution was very obscure (read: probably not your problem, but it did happen to me)...

...I had a sub that was older and used very very hard. The tinsel leads ended up becoming faulty and it resulted in the sub only playing with a very strong amp output. I reconed the driver and the problem was gone.

If your problem is the amp (possibly deteriorated MOSFETs) I would recommend trying a Cadence amp. Their amps are an incredibly good value and the quality and customer support is top notch. Read car audio forums about their products.

I bought a Cadence class-d monoblock amp through their own ebay store and it has been fantastic. Look at this link for a refurbished mono 500wrms. maybe get two of them.

trader007

i had a set of 6" cadence component speakers that were ok, but a little hollow sounding. that amp looks nice though, i like the power and speaker terminals. cadence has been around for many years now, always considered an option for many good installs.

fiXXXerMet

Well I connected my MP3 player directly to my amp using a standard headphone-to-RCA Y cable and the bass sounds amazing. Even turning the volume on the player very very low, the sub continued putting out sound, where-as running the MP3 player through the head unit - or using the head unit with a CD - at that volume, the subs would not output anything.

I have some more diagnostics to do before I rule anything out, but it seems like the amp is OK?

trader007

i suppose so... weird problem man. next you have to check the cable from your headunit to your amp... does the headunit put out normally with fm radio?

Phoenix750

Yea I agree with trader007, I bet it's your cable.

Maybe try using your test setup like this:

MP3player > headphone/RCA cable > RCA amp patch cable

This could identify if the patch cable is the problem (since you already know both the amp and headphone/RCA cable work).

hithere

Check your RCA connection against a known good cable. Check your head units crossover settings (if it has them), also check that the amp is coming on with the car (there's a remote wire from a switched DC source), and that it's not relying on voltage sensing on the RCA's to turn on, if it has this feature. If this feature exists and is engaged, you can also try adjusting the input sensitivity on the RCA's to get the amp to fire up with a lower output voltage from your head unit. Also, check your remote lead...if using one from the head unit, replace it with a direct feed from a switched DC source in the car (you can use a fuse holder/remote lead available for your car for a few bucks at any car audio dealer).

__________________
I have too much time and too little aggravation in my life, so I built a carPC. ;)

MP3Car.com