My Amp is Dimming

Gutter · 05-05-2002, 01:49 PM

Ok, so I picked up a 400w Jensen 4 channel amp at Best Buy last night. It happened to be $80 instead of the normal $199. I hooked it up to my system and I could finally hear the music coming from my system. With all the knobs on the amp turned to minimum, I started raising the volume in my software. When it got to about 70 - 80 db (rough estimate), the amp started beeping and the lights on it dimmed in and out. I'm guessing that it's a power problem, but since I have zero experience with amps, I wanted to ask you guys. Should I run a seperate 10 gauge wire from the battery to the amp?

jol · 05-05-2002, 02:58 PM

I will setup my system kinda like this:

phat car = common ground

ok, that many fuses is overkill, but helps trouble shooting..

Alives · 05-05-2002, 04:23 PM

yeah i told you... AVOID JENSEN AND JVC... jesus... if you dont want to listen, how will you ever learn anything?

monger · 05-05-2002, 04:49 PM

You said that you were turning up the volume with software. My guess is that you were feeding the amp with too much power in the LINE level inputs. Heres the solution, set your software volume in winamp to about 2/3 max. Set the main volume to about 1/3 to 1/2. THEN adjust your amp gains (shuold say level or something along those lines) until the speakers start to distort. Then turn the gain level down a few notches. This way your computer is not feeding the amp more power than it can handel on the imputs.

Then again, how exactly are you powering this thing? What are you using for speakers? Are you using the POWERED output on your sound card?

The above was just a guess as to what the problem was. A little more info would be helpfull.

Alives · 05-05-2002, 05:06 PM

no, you want winamp turned up ALL the way... it will give you a cleaner signal.

here are your problems:
1) Jensen
2) you need a direct fused line from the battery... at least 8 guage
3) you need to quit being a cheap skate

Gutter · 05-05-2002, 06:54 PM

First of all, Alives, STFU. Your opinion is no longer requested. You have my sincerest apologies that Jensen amps trouble you so. As I said in the other thread, I just needed a cheap way to amplify the sound coming from the soundcard. I'm not about to spend $200+ on an amp to power my stock speakers. Maybe if I had better speakers or actually gave a flying ****, I'd spend more.

Prehaps therapy will help your need to crap on other people. Take your inferiority complex and bad attitude somewhere else.

As for the amp, I fixed the problem. I ran 10 gauge wire from the battery and it doesn't dim anymore. It sounds great, and had my stock speakers rockin'.

Alives · 05-05-2002, 06:57 PM

sounds like my suggestions helped

magnetik · 05-05-2002, 07:15 PM

Quote:

Originally posted by Gutter
As for the amp, I fixed the problem. I ran 10 gauge wire from the battery and it doesn't dim anymore. It sounds great, and had my stock speakers rockin'.

good to hear you fixed it.... I didnt realise that thick power wire would be THAT important.... now I know...

Alives · 05-05-2002, 07:17 PM

low voltage high amperage... thats why they sell 4 guage and 0 guage...stuff is ridiculously thick

|<amikaze · 05-05-2002, 09:54 PM

Quote:

Originally posted by Alives
no, you want winamp turned up ALL the way... it will give you a cleaner signal.

depending on your sound card. my sound card starts to clip the output at 100%, i find that it stays clear up to about 80%

JamesB · 05-05-2002, 10:59 PM

Your Jensen is likely a perfectly fine amp.
My first amp was a Jensen and I was thourougly impressed with it - so don't listen to anybody who knocks your gear.

Most importantly though: the reason your amp is dimming is because it is entering a protection mode to prevent failure. The problem is twofold:

1) you should ALWAYS use a large gague wire for the amp - check what the fuze rating is to determine the gague of the wire required. For your 400w amp, the following is true: always use the "maximum" rating by the way (for power consumption)

amperage = watts % voltage

assuming you are running at 12.5v, your amp will draw 33.3 amps, so you will need both a 35-40 amp fuze and a wire gague that will accomodate this current. Be sure to select the proper DC amperage / wire gague as the AC values will differ (in wire size).

2) you are feeding the amp with either TOO MUCH input voltage, or TOO LITTLE input voltage. Ie. your sound card is not properly "line balanced" for the amp. My guess is that you are feeding it with too much. Most amps (non-high end) are only meant to be driven with up to 4v (ie. a 4 volt input source from the RCAs). Higher quality amps such as the high-end (expensive) Pioneer, Alpine amps and ALL phoenix gold amps accept up to 8v input.

If your soundcard is not outputting enough voltage, you can (and should) buy a "line driver" to PROPERLY boost the input level to an acceptable voltage for your amp.

If you are "under-driving" the amp with a low input signal, you are likely introducing a large degree of noise causing a "clipping" effect. (clipping is when the output from the amp goes too high for the electronics and is "flattened out" causing DC output (amps are designed to aomplify an AC (music) signal). Think of clipping as when you look at a sine graph and draw a line at 45' (0.707) on the Y axis both positive and negative - then erase all the "peaks" of the wave crests and leave the flat line .. then erase the line between latent waves.

Does this explain enough for ya? If not, let me know ;-)

C4M · 05-06-2002, 05:13 AM

Quote:

Originally posted by Gutter
First of all, Alives, STFU. Your opinion is no longer requested. You have my sincerest apologies that Jensen amps trouble you so. As I said in the other thread, I just needed a cheap way to amplify the sound coming from the soundcard. I'm not about to spend $200+ on an amp to power my stock speakers. Maybe if I had better speakers or actually gave a flying ****, I'd spend more.

Methinks he has serious issues on Playing Nicely With Others.

Quote:

Originally posted by Gutter As for the amp, I fixed the problem. I ran 10 gauge wire from the battery and it doesn't dim anymore. It sounds great, and had my stock speakers rockin'.

Make sure that you have an appropriate sized fuse inline between the amp and the battery. IASCA competition requires that the fuse is within 18 inches of the battery. I know that you don't care about competing, but fuses are way cheaper than amplifiers (even Jensen ones

).

C4M · 05-06-2002, 05:14 AM

Quote:

Originally posted by Alives
sounds like my suggestions helped

Not really. 10 gauge is actually smaller than your suggested 8 gauge.

JamesB · 05-06-2002, 12:52 PM

Actually .. the use of a fuze to protect the amp is a bit of a misnomer.

The fuze is to prevent an open circut in the event of an electrical short along the power-line. Ie. if you are invloved in an accident and the vehicle body pinches the power-wire, causing a short .. you want the fuze to blow to protect your car's electrical .. and to prevent fire.

C4M is correct in saying _within_ 18 inches. Some people actually say 12" max.

PS: Don't run any "signal wires" on the same side as you run the power wire. Just another "no no" =)~

wizardPC · 05-06-2002, 03:44 PM

okay, I have been lurking on this post but I just realized that you bought the amp that I want, for half the price I can get it

I am 350 miles away from the nearest BestBuy, but I am going there wednesday. Was that a Weekend special or are they still on sale (everywhere)?

User Name		Remember Me?
Password