To 01Price: about your message in "Check out my system. Opinions and suggestions..."

[Unregistered]

"Bridge the amp's channels together and send thoose JLs 160 wRMS, set the frequency at around 160hz, and they should eat it all up. The reason they say to only put 75 wRMS is cause if you give them 100 wRMS and play them at around 50hz or so they will blow, but setting the frequency up higher, you can slap on the power no problem, they might even take more."

What exactly do you mean here? Are you suggesting that I should bridge the front and rear right channels and the front and rear left channels of the amp and use it to power the front speakers and then buy another amp for the sub?

If this is the case, each of the JLs will be getting 320wRMS, not 160, since 80x4 = 320. Obviously, way too much power.

Or do you mean that I should bridge the two front channels and power the front JL speakers off that and let the two bridged rear channels power the sub? This comes with it's own set of problems. The most obvious is that I will not be getting stereo out of the front speakers since bridging two channels results in a mono signal. Secondly, each of those JL components are 4ohms. This means I can wire them in parallel and get a 2ohm load or wire them in series and get an 8ohm load. Now, let's look at what happens when I bridge the channels in each of these situations. First, the amp is not stable at 2ohms bridged so that rules that out. Second, if I bridge the channels and send the power into an 8ohm load, I will only be getting 160wRMS total since doubling the impedence cuts power output in half. That means each speaker will get 80wRMS, the same as it would if I just ran the channels to each speaker individually. So there's no point in doing that. Plus it would be a mono signal.

Please correct me if I am wrong here.

Thanks,

Mike

Click to read more...

 

[01price 10+ year member]

If this is the case, each of the JLs will be getting 320wRMS, not 160, since 80x4 = 320. Obviously, way too much power.

Bridge the left front and left rear channels to give you 160 wRMS for the left compoent sets and the right front and right rear channels to give you 160 wRMS for the right compoents. This will give you a total of 320 wRMS with both sides combined. The components you bought must have been as a pair, the rating of 75 wRMS is for each "set" as in 1 set is the left speakers and the other set is the right speakers. They will be fine, just don't turn the volume to full power, which you should never do because ALL head units start to clip around 80% volume.

The most obvious is that I will not be getting stereo out of the front speakers since bridging two channels results in a mono signal.

If you bridge the front and rear channels together, you will still get stereo with left and right channel sound.

Secondly, each of those JL components are 4ohms. This means I can wire them in parallel and get a 2ohm load or wire them in series and get an 8ohm load.

I doubt the components are dual voice coil. I have never heard of a component speaker being dual voice coil. If they are, then yes you would have to wire them as 2 or 8 ohms. But since they are single voice coil, they will present a 4 ohm load to each of the bridged channels to your amp, still 160 watts for the left and 160 watts for the right.

I highly suggest buying a seperate amp for your subs. They need a dedicated amp to run them properly most of the time. There is virtually no difference between stereo and mono sound in sub bass frequencies, so I would suggest trying a mono block subwoofer amp to power them. A class D amp would be more efficient and cheaper.

 

[Unregistered]

"Bridge the left front and left rear channels to give you 160 wRMS for the left compoent sets and the right front and right rear channels to give you 160 wRMS for the right compoents. This will give you a total of 320 wRMS with both sides combined. "

Ok. This is where you have me confused. You say that if I bridge the left front and left rear channels and the right front and right rear channels, I will get 160wRMS per side, for a total of 320wRMS combined.

Now, it is my understanding that bridging two channels of an amplifier results in 4 times the power out put of one of the bridged channels, not twice the output.

So, if I bridge the front left channel, which is 80wRMS, and the rear left channel, which is 80wRMS, then the total power for that side that I will be getting is 320wRMS, not 160wRMS. Same goes for bridging the front and rear right channels.

So, in the setup you recommend, I would be getting 320wRMS per side, or 640wRMS combined.

But you say that bridging the front and rear left channels and the front and rear right channels will result in 160wRMS per side, and not 320.

Please explain to me why bridging two channels in this instance only results in double the power and not quadruple. I was always under the impression that briding channels resulted in 4 times the power output, not twice the output.

 

[IASCA pro 301-6 10+ year member]

That confusion can be traced back to the early 90's when "cheater" amps came out. They were designed to give a totally low amount of power at 4 ohms...like a certain amp from the northwest that made 22 watts total power at 4 ohm. But as you dropped the ohm load, this amp would produce tons more power, like 160 watts total at 1 ohm.

The misconception came when there were some amp companies who's marketing people really went beyond the grasp of engineering. It is true given this senario:

Amp has 50 watts per channel, two channel amp.

Sub is single voice coil 4 ohm sub.

When the amp is running stereo, the sub gets 50 watts.

Now, bridge the amp and the amp is capable of 100 watts at 4 ohms. But...take that same sub (4 ohm) and when you apply that to a BRIDGED amp, the amp usually "sees" half the load, so the amp is now running at 2 ohm, and usually putting out twice the power.

Tada...you now have 200 watts pushing your sub...

There are some things that have changed this...mono amps do not behave like bridged amps, some newer amps have circuitry that allows them to compenate for different ohm loads. Plus, the actual output of an amp is questionable when bridged and what type of ohm load it is actually pushing.

If you follow the advice given above, and utilize all four of your amp channels, you will get some great power, and not have to push that amp that hard. That's what I would do if I were in your shoes...