I just installed a Kenwood 649S 4 channel amp(30x4 RMS) to power some polk speakers(6 1/2" front, 4" rear). Everything works fine, but I'm unsure on how to set the input sensitivity. Is there a general rule of thumb to go by?

Thanks!

PS 2001 stock HU

 

Bueller? Bueller? Bueller?

 

Well, if your a "geek", you have access to an O-Scope and a CD-Burner...

(I've posted this before)... Basically create 2 wave forms on the CD (and either make them 10min long each, or set your deck to repeat the tune).

Create 1 120hz frequency, and a 4k Frequency tone (1 tone / track). At MAXIMUM amplitude.

Place the O-Scope on the output of the AMP... and turn the deck up to ~90-93% max volume (not 100% as the deck probably naturally clips).

Then look at the output on the scope... you want the sine-wave to be "smooth" and not have flat-spots at the top/bottom of the waveform. Dial the gain on the AMP until this is achieved, without adjusting the deck volume. This is the MAXIMUM power w/out distortion you can obtain.

Also, this leaves some room (that 10%) for stations/CDs which aren't normalized to have maximum output (thus you can boost them up more).

Hope that helps,
Aaron
p.s. If your even in Austin, you can swing by my place and I'll help you tune it if you don't have access to this equipment.

 

Well, I won't confirm or deny the "geek" part!!!

That's a little more involved than I was thinking of, but thank you for the info(& offer) just the same!

 

You can go a step further and use the scope to find the actual clipping point of the CD deck. Hook the probes to the RCA line and adjust the head unit volume until you see that curve clip, then connect it to the amp and do the same. Wish I had one handy to adjust mine.....actually, I have a 1GHz digital scope with a touch screen sitting on my desk at work, but I can't take it past the security gate.

Jeff

 

Yup..its by-far the BEST way to tune your deck/amp...

S2KFanatic, find a friend who knows how to use a scope and rent one or have that friend barrow one... its WELL worth the effort.

You system will ROCK if you do this... I'm serious. You turn it up-- and it just gets LOUDER, not distorted.

The down side of not doing this, is one of the two can 'clip' long before max power is obtained, causing 'pops' and potentially damaging your speakers. Not to mention sounding like crap.

-- Aaron