My Amp is Cutting Out with Every Bass Hit?... More info...?

Question

I know quite a bit about car audio and cars in general, but having a problem with my amp. I have a Sony 1200W amp with two 10-inch subs which are currently bridged (formerly paralleled) with an Alpine head unit.

The head unit enables me to control the amount of bass, but regardless of the settings, the bass cuts out of power quite quickly.

I know it is not the amp, I have tested two. I know it is not the head unit, since I have tested the amp on another car. More than likely it the problem lies with the wire.

Yes, I do not have a capacitor, but I am running a new alternator and an Optima Red Cell Battery.

This question only goes out to very experienced car audio people out there. I am wondering if the problem lies with either the wire connections or the setting on the Amp/head unit. I've been playing around with it for a while, and still its annoying me.

Well, I plan to lower power switch on the Amp itself. I figure that lowering the switch, and controlling the power by the head unit may solve the problem. I have used this same setup including the Amp, wires, and subs before.

The Subs, I believe are 2 Ohm. I'm sure that no one out there unless you live in Chicago would know of the brand. They are called DJ Pops! The maker and seller is one of the founders of the company Bose.

These subs are pretty inexpensive, but will out hit anything under $300 a sub each.

Answer 1

After reading your question, there are a couple of situations where this could occur.

a) if your subwoofers are 2 ohms, and you have them bridged, they are presenting a 1 ohm load to your amplifier. Last I checked, the Sony amplifiers were not 1 ohm stable. IT could be going into protection mode

b) when the bass hits, it could be draining excessive amounts of power, dropping the power supply below 8-9 volts. Most amplifiers require at least 8-9 volts to operate. Again, the amplifier may be going into protection for inadequate voltage.

c) the final scenario is you may have a bad MOSFET on the amplifier itself.

If your amplifier was running fine when you had the subwoofers wired in parallel, I would recommend going back to parallel wiring and seeing if it functions properly. Another to check is, with the system running, get a test meter and check the voltage at the amplifier. Have someone gradually increase the volume on the radio and watch the voltage reading on your test meter. If it is dropping below 8-9 volts, adding a capacitor may help.

Finally, try disconnecting one of the subwoofers and run the amplifier to just one subwoofer and see if the problem persists. If the problem goes away, you may have a blown subwoofer causing an internal short to ground - again, sending the amplifier into protection.

Without actually seeing the set-up and evaluating it visually, it is difficult to diagnose, but these are at least some places to start.

If you check all of this and the problem still exists, let me know your findings and I may have some other ideas: [e-mail]

Answer 2

Yah you are in the ballpark with several of your theories.

1. Overdriving an input could possibly cause what you say. Check line in levels.

2. Caps are cool but only make up deficiency a little. Its much more dependent what size Alt you have.

3. Bad wires could possibly be? Check continuity? Check actual resitance with an ohmmeter. You want to see a steady/set (hopefully low) resistance. Infinity is bad (open) and a set resistance then slowly climbing to infinity could signal a loose barely touching or intermittant connection. Also guage size is important. (you can never have too big wires) and grounding? Decent gauge ground AND solid ground connect!

4. Would be interesting to put a voltage check in-line to subs and see what voltage is hitting? And HOW the voltage is acting. Two subs parralelled at 2 ohm each was hard on the amp, it was "seeing" less than an ohm! I am getting that by "bridged" you mean series which would make the impedance 4 ohms. Are you talking about bridging the amp like stereo to mono? If so does it happen both ways or just one way? (I personally don't like impedance setup less than 2ohm because although you see high power the power gets real "loose" and is hard to control for the amp). For bass I like specialty "bass amps" because they tend to have high dampning factors (essential to control those bass speakers).

5. Finally cutting can come from an overheating protection circiut and I only mention this because I don't know what kind of cooling the amp gets.

Good luck!

Answer 3

What size wire are you using for the power to the amp? Both hot and ground. Basically you're not getting enough power to the amp when the bass puts a high demand on it, causing it to cut out. You could also be over driving the inputs to the amp but I'd still bet on inadequate power wiring.

Also, check the impedance on the subs at very low frequencies. It may be too low and is putting too much of a load on the amp. A really good audio shop can test that.

Answer 4

Use a heavier Gage wire and better connectors.
I use # 8 wire to run a 200w stereo and #4 for the amps-wire each seperately and dont skimp on the ground wire it is just as important.
If you are using the frame as a ground also run a wire to the - battery terminal. USE BOTH
Do not use quick conectors anyplace.
If a splice is needed solder it and cover with shrink wrap-tape will not last. Soldering creates a permanent, professional connection that ensures maximum current transfer.
+ Wire to the battery should have an inline fuse close to the battery.
Run wires seperately from others to reduce hum.
Add another battey close to the amp.

Answer 5

Check your ground wires! I bet it has something to do with that. Your amp is bridged huh? Try lowering the amp a little and then checkin your ground wires. And also try (if you drive a car: open up the turtle hole and turn your speakers up side. I'll waiting to hear from you again to let me know if you tried that. Normally a 1200 wat amp pushes two 12's. Personal experinece with my system.

Answer 6

It sounds as if your amp is starving for power. You may want to invest in a 1.5 farad cap.

Even though you have a new alternator and awesome battery it just doesn't make sense.

Ahh, gremlins...

Answer 7

you need a 1farad cap to store the power from the battery and give to amp.go to best buy, circuit city, or local sound shop. if you still have a problem then you need to get a bigger amp.

Answer 8

Sony mono amps are not 1 ohm stable, its going into protect itself...unbridge it and get different subs...

Answer 9

its a sony! any more questions?