Help with Bridging Amp

Hi,
I have a 2008 Reg Cab 4cyl/5sp 4WD that I upgraded sound on a year ago. I've got a Kenwood KDC HD545U hooked up to a JBL GT5 A604 Amp which powers JL Audio component speakers in the doors. I have a powered 8" bazooka behind the seats/console which is input directly from the head unit. I have one set of RCA cables running from front output on head unit to front input on amp.

I read in my JBL GT5 A604 manual that it's "bridgeable" for stereo (running 2 channels in lieu of 4) or for a sub. The amp isn't connected to the sub at all. I followed the bridging instructions provided by JBL (Connect one speaker (in my case wire to crossover) to Front R+ L- and the other to Rear R+ L-) and now sound only comes from the driver's door speaker.

Nothing from JBL or Kenwood says anything about changing inputs to bridge in stereo. Many threads I've read on message boards say that most amps "bridge" automatically. Some amps require that you run an extra set of RCAs from rear output on head unit to rear input on amp, but NOTHING JBL says even hints at this.

I stupidly paid a $5 3 month membership to a DIY Audio Board and 75 people read my thread with no replies. Guess they ignore noobs...

Thanks in advance for any help I can get. Everything else I've ever wanted to know about Tacomas came from here!!

Elroyyboy

 

You'll need either two sets of RCA cables or there might be a mono/stereo switch you will have to hit.


4 channel amps are kinda like two 2 channels rolled together. The two sides don't think together much

 

OK, thanks for the reply. So, if I do this, I'll actually use fader to control balance? Since the extra RCAs will be coming from rear channel outs on head unit?

Thanks,

 

Yeah and you will have no F/R fade since you are only two channel. You could theoretically use a short set of RCA cables and use the passthrough channel to power the other side.




Might I inquire to why you are bridging? What are you powering?

 

I've got a pair of JL Audio VR 525 CSI component speakers in the door. I just thought I might get a little cleaner, and possibly louder, sound w/ bridging.
I'm retired from Army and really don't have much to do, so I guess it's "advanced Piddling."

Thanks for your help!

Elroyyboy

 

you cant just bridge an amp and hope for the best... You need to know the peak and RMS ratings for your speakers and for your amp.

Your speakers are rated at 15-60w RMS and 100 Peak. They are also rated at 4 ohm's. Bridging will cause your speaker to run at 2 ohms and they may not be able to handle that type of load which will damage your speakers and maybe even your amp.

Your amp is rated at:
RMS-
4 ohms: 60 watts x 4 chan.
2 ohms: 80 watts x 4 chan.
Bridged, 4 ohms: 160 watts x 2 chan.

Max power output-
160 watts x 4 chan.

This means that if you keep them wired up as normal (1 speaker per channel) they are getting about 60w rms each which is their limit and 160w max which highly exceeds their limit. By bridging the speakers, you will push 160w per speaker RMS and MAX which will very quickly blow your speakers out!

If your speakers are not clear enough, its probably because they are already getting too much power as it is, or they are not tuned right. Your head unit EQ should be turned off and set everything to "0" or "flat", then adjust your amp gains at about 75% volume as well as your HPF control. After the amp is tuned, then adjust head unit EQ.

Dont bridge these speakers on this amp!