can someone explain amping and bridging?

Looking to put a small amp in my truck to all 4 speakers and possibly a sub, what do I need. 2 amps. What's this bridging and crossover nonsense? What happened to the days of plugging in new amp and running everything.

 

You want to run 4 speakers and a sub? No problem.

My suggestion would to buy either a 4 channel amp or a 5 channel. A 5 channel amp has a channel for each speaker and the sub. This will give you full control of the fader (increasing the volume for the forward or rear of the vehicle). Crossovers allow you to only send certain frequencies to certain channels.

So in the case of a subwoofer, you want it to only receive 80hz and down. You would set a Low Pass filter at 80hz to accomplish that. For your speakers, you might only want them to get 80hz and up, so you'd set a High Pass filter for 80hz.

You could also get a 4 channel amp and run both sets of speakers off the front two channels of the amp. You'd parallel the wires on those channels. Then, take the rear two channels and bridge them for the sub. This usually involves taking the + from one channel and the - to the other channel and using them. Check out some wiring pictures from amp manufacturers for graphic representations. The only bad thing about using a 4 channel is that you will not have the ability to use the fader for the main speakers that are running on the same channels. So if the rears are too loud you won't have a way to fix that.

 

I get it kinda? When you say setting low pass is that from the amp controls? And if I did 4 channel and used -+ from one pole what about other. Are we talking about power to amp from car to sub? Guess I just have to buy to really see and understand. Any suggestions on 4ch or 5ch?

 

Crossovers are always on the amp unless you happen to have a headunit with crossovers and or a processor.

And with respect to bridging, I mean take the + from say Ch3 and the - from Ch4 and send them to the sub. That's bridging two channels.

And it would be impossible for me to suggest any amp without knowing the equipment.

 

Yup. There are a TON of good quality 4 channel amps. There are less in the 5 channel realm, but enough to make a budget/size/power decision.

Come up with a power requirement or desire, budget, and footprint, or size of the amp you can swing, and then suggestions will come rolling in.

 

Thanks guys. I am looking into a 5ch amp because I want to run 4 speaker and small 8-10inch sub. It's been a while since I put an amp in and tech has changed. I will most likely run amp with speakers then purchase sub down the road. My speakers currently can handle way more power than hu supplies.

 

where do you plan on mounting it, and what kind of power do you think you want?

 

My experience (not much) with the five channel amps was never great. I have always liked a two amp setup better. Take that for what it's worth but I have had better luck with a good 4-channel(2-channel in my case) amp for the mids/highs, and a good mone amp for the sub. Mono meaning single channel. It has been about 7 years since I used a 5-channel so they may have came along way with them. Good luck!

Edit: To clarify I have gotten better sound quality out of a 2 amp setup.

 

I have never had an issue with combining uses in the same amp (full range and sub frequencies).

When you say better sound quality, what do you mean? Noise floor issues, channels bleeding over? disparity in volume, cutting out?

Was it a high quality unit, average, or cheaper stuff? I dont mean to insult you or your installer, but are you sure it was installed correctly? Crossovers and gains set properly?

 

I was actually considering doing a 4ch and mono amp setup also. I may do this because I can get a good quality 4ch now and find a mono and sub later.

 

I have a JL HD900/5. I know you guys are tired of hearing about it but it's fantastic. I'd put that thing up against anything.

The only problem I ran into when thinking about running a 4 channel amp and bridging the rear two channels for a sub was that most of the amps will only bridge at 4ohms and are NOT 2ohm stable. This limits your amp choices quite a bit.

That Kenwood 5 channel is damn good for the money IMO.

 

fixed.

I would rock the kenwood all day, same with the newer PDX. Or the JL XD or HD. I would even try the Arc XXD, or new 805. Or the new Polk/Hertz. Or the PPI Phantom. etc.
Hell, even a lot of those new super mini RF amps. Lots of choices...

 

What Kenwood? Where's the best place to mount amp?

 

Kenwood XR-5S is most likely the one Matt was referring too. That, the Alpine PDX-5 and the JL HD900/5 are the biggest hits right now the the 5-Channel Class-D world. The JL XD700/5 looks like a great option as well.

My advice? Get the Kenwood or Alpine and don't look back. The Kenwood has more power to the sub channel, the Alpine has been around a little longer and allows use of a remote bass control knob. Other than that they are pretty much identical. If you decide you have the extra cash ($700ish) get the JL HD900/5. I haven't heard it, but everyone that has one raves about it.

 

Yup, the XR5S. Those three are the biggest (I would venture that the XD700/5 is selling better than the HD at this point, based on price...) due in large part to the massive number of dealers, and reputation those companies have.

There are a lot of options, but those are easy to find, relatively small and affordable (sans the HD, which retails around $1k).

 

Yep, I'd take the Kenwood for the same reasons. That wasn't available when I got the JL and honestly, I don't know what I'd get if I was buying new today. It would be tough for me to choose between the two. I do enjoy the extra power headroom on the JL but I know mathematically it's not that much different in terms of sheer output.


And Matt thanks for the correction. Total brain meltdown on that one.

 

Alot more to amps than just advertised power output

 

As long as the signal to noise ratio is fair it's typically fine. THD on amps is scary low when you stop to think about how much THD speakers add to the sound. .01% THD from an amp is irrelevant when a speaker adds closer to 3% into the mix lol

 

so your saying the difference between a $70 pioneer 150x2 amp and say an $1100 McIntosh 150x2 is slightly better s/n and thd?

 

Not what I said at all. I stated that as long as those two specs are within reason (and the amp makes rated power) then "it's typically fine". At no point did I say it was worth spending $12,000 on snakeoil capacitors.

But I'm curious to see what YOU think the difference between the grand spent on a high class label amp and a budget amp with 'decent' specs actually nets you. What specifications do you attribute to be the difference makers?

I have a small 2x10watts Sonic Impact amplifier at the house. It was $60 new. In a double blind test I don't think you could tell the difference between 10 watts out of that vs a $1000 tube amp producing the same power. And the real kick to the balls is that in a car, on the road, with the engine on....let's not even go there.