Distortion from car speakers when bass hits

[arthos4551]

I recently bought two sets of Polk DB652 and a JVC kd-r888bt receiver to install into my 1984 Nissan 300zx GL. The previous owner had installed a cheap receiver but did not change any of the 33 year old stock speakers. When i purchased the car and got it running i never used the receiver he put in due to it lacking any modern capabilities like Bluetooth or any type of aux/USB connections.

I then installed the new JVC unit and tested out the stock speakers for the first time. They sounded pretty good but there was distortion on bass/loudness in general. I originally thought i was just overpowering the stock speakers due to how old and low their specs were.

So i installed DB652s in the doors and the rear "deck". To my discomfort I'm still getting distortion from all my speakers when any type of bass hits. I've gone through each speaker to make sure the visible wiring was correct.

I'm not an expert on audio in general but does anyone know of any ideas on what could be causing this distortion? Could i be under-powering the speakers now and would the distortion sound the same as when overpowering them? Could there be something wrong with the hidden speaker wires underneath the carpet?

To add, the GL models had a common ground system where the left front and rear shared a ground and the right front and rear share a ground. Could this be causing the problem?

 

[lumineZ]

You are not saying anything about your volum level when this distortion starts. Low? mid or high volum.

Worst you can do to speakers is underpower them when you turn the volum up high.
At normal listening levels it does not matter at all (unless the amp you are using cant handle that load either)

 

[dish_moose]

Full Bandwidth Power (at less than 1%THD) 22W x 4
Your speakers are 100W continuous rated. I have never been a believer of specs from most car audio. Unless the amp states rated power as RMS continuous power - it's just numbers on a piece of paper. You need to get an amp and use the rca outputs to a proper amp (subwoofer as well if you can afford). Cranking up any amplifier beyond its capabilities will toast your speakers faster than you can imagine.
-Bruce

 

[arthos4551]

You are not saying anything about your volum level when this distortion starts. Low? mid or high volum.

Worst you can do to speakers is underpower them when you turn the volum up high.
At normal listening levels it does not matter at all (unless the amp you are using cant handle that load either)

Unsure of the max volume limit of the reciever but judging from the actual sound it seems to start around mid.

 

[arthos4551]

Full Bandwidth Power (at less than 1%THD) 22W x 4
Your speakers are 100W continuous rated. I have never been a believer of specs from most car audio. Unless the amp states rated power as RMS continuous power - it's just numbers on a piece of paper. You need to get an amp and use the rca outputs to a proper amp (subwoofer as well if you can afford). Cranking up any amplifier beyond its capabilities will toast your speakers faster than you can imagine.
-Bruce

My main concern is do i need to exactly match the 100w continuous rate or can i get close to it? I have A Planet Audio AC800.4 that will provide 75w rms per channel that i can pull from another car if it will suffice.

There's also a Planet Audio AC1200.4 that ive been looking at but its rated at 113w rms per channel.

I guess my main confusion is how much rms wattage is actually required. Is it safer to go abit over?

 

[dish_moose]

No you do not have to match the power output of your amp with how much your speakers can handle. From my experience( used to sell fairly High End Audio many moons ago) people had more problems with a smaller amp and higher capacity speakers than the other way around. As long as you don't turn it up to cause amp distortion, your system will be fine. As for the volume only up to 1/2 - there is always more gain in an amp than you can use - in many cases just over 1/2 will be max output. The reason for this is not all input levels are the same - with a lower input level source you still want to be able to get max undistorted output from your amp.
-Bruce