amp/sub/headunit troubleshooting-getting a "thump"

[calreef18]

So I finally got around to changing my sub from running through a line out converter from the rear speakers into the amp (kenwood kac-7201) in a 12" audiobahn sub, to going through my new headunit's (pioneer dvh-p5000mp) 2v preouts. However, I've encountered two problems. One is minor, where I had to raise the gains/lpf on the amp from where I had it set originally when it was tied into the rear speakers so that the sound coming from the sub was the same loudness. Is this normal? Also, the second which kind of bothers me, now when I switch from say tuner to cd mode or vice versa, or when the head unit turns on at first, I get a *thump* sound from the sub, what the heck is that about? Anyways, thx in advance for the troubleshooting tips.

*edit* finally found some info, looks like a surge from the headunit and it was suggested I could put a relay imbetween, any tips on doing that?

[88 LE]

Originally Posted by calreef18

when I switch from say tuner to cd mode or vice versa, or when the head unit turns on at first, I get a *thump* sound from the sub, what the heck is that about?

Turn on/off thump from the amp.

finally found some info, looks like a surge from the headunit and it was suggested I could put a relay imbetween, any tips on doing that?

I don't think a relay is going to help in this case (turn on/off thump).

But if you want to try it, heres how you wire it up:

87: constant +12V
87a: not used
85: ground
86: remote turn on lead from headunit
30: output to amp. wire to remote turn on the amp

You need a 12V automotive spst or spdt relay. SPDT will have a terminal labeled 87a, but you won't use it. SPST does not have 87a.

[calreef18]

I only get it when it turns on.