Can a "bad" amp make a a SUB sound.......

broguearcher

poor even though it is still producing a lot of bass?

Here's my deal: Have a used 10" SVC MOMO Sub that I was using in my car with a cheap Lightning Audio amplifier..... built a nice sealed box for it of the correct size. The sub sounded pretty great for the most part but when it was pushed to any kind of intensity (even fairly low) it would develop a rather disturbing buzzing or grating, even a "torn" kind of sound. I eventually figured that the sub was blown and ordered a new one. I decided to get a 10" DVC MOMO (not the best choice for my set up I now realize but I didn't then). I tested that (BRAND NEW) sub out yesterday and what do I get? The same damn sound!!! Buzzing, vibrating, etc..... It seems like the amplifier is passing on some rather rough distortion at low frequencies. Does this sound plausible or do you think that I actually have had the bad luck of simply getting two bad subs?

My other theory is that the amp is simply just not powerful enough to cleanly produce the bass needed and this is why the subs begin to start sounding really rough. The amp can only do 150W bridged into 4 ohms. Polk apparently recommends 200W RMS for these speakers.

I disconnected the amp from the sub and ran it in stereo mode to my 6x9's in the car.... they actually sound OK I think with it. Loud and strong. However, I MAY be able to detect some levels of audible distortion at low frequencies in them as well. However, they don't need nearly as much power to operate well as the subs require. Thoughts? Looks like I just need to buy another amp and one truly capable of putting out the power? Some of this situation just doesn't make sense to me.

Thanks.

1996blackmax

I would think that two different subs having the same issue is not very common.

Have you made sure that your box is perfectly sealed? Things can start to sound bad if you have an air leak and then push the sub. The leak can come from an an edge or a corner, the wire terminal, or even the mounting area where the sub meets the box. I actually had to add a little more silicone to my current subwoofer box.

How do you have that DVC sub hooked up to the amp right now?

If the gains are not set correctly the amp can start having issues when pushed. If the sub is rated at 200 watts RMS, it does not need the full 200 watts to sound good. It should do fine with less. Usually the RMS rating is the thermal capability of the sub, many subs can actually reach their full excursion before their RMS rating. Do you have a loudness button engaged? How about a bass EQ on the amp, if it has one? This can bring issues, especially if the amp is not set up correctly.

broguearcher

the amp is set correctly from all that I can determine. The issue is not due to an air leak I don't believe.... because when the sub is even played a little bit OUTSIDE of a box it will still make the exact same noise when pushed even a little. When the sub was in the box it was sealed pretty dang tightly.... also POLK says in their speaker manual that these subs can be used in ported enclosures as well if desired but are designed for sealed boxes.

I am just hoping for some answers on why this amp is producing such poor sound from two different subs... The bass is definitely there but I don't want to push the subs if they are ALSO producing such a disturbing noise.

Even though this amp might be rated for 150W I do really doubt that it's putting out that level of power especially considering that I don't have it set for max output due to the fact that most amps don't seem to do well when they are maxed out. This amp might not be capable of much beyond 50% output without distortion....

broguearcher

forgot to add... the amp does have a bass "boost" button on it.... when engaged the bass is much more impressive but it definitely makes the "bad" sound far more prominent. With my problem more bass = more of the vibrating sound.

Sam

1996blackmax

Sounds like you have an issue with the amp.....

The only other thing I can think of it's a bad RCA cable or connection. This would be a long shot though. It may be time for an upgrade .


I was asking about the bass button because alot of people misuse it. I actually do not have function engaged on my system.