I just got a set of polk/momo 6.5 components and i have an mtx 4244 which is 45x4, i wanna bridge this amp to run just my front speakers. Is this gonna work good? I just want around 100-120 x 2 if thats possible but someone told me it wont sound good because it would change from stereo to mono.

 

It will change to mono and the distortion will go up 10 fold.

 

I quoted this from a dodge dakota forum that i found searching 4 channel bridging on google. But this guy was tryin to do the same thing except with a 5 channel orion amp that has a sub channel but is the stuff pertaining to bridging the 4 channels in this correct?

The difference between mono vs stereo is one channel (mono) vs two channels (seperate L and R). With the amp configured at 140x2 + 130x1 the front two channels will still be in stereo as long as you send the right-side signals to one channel and the left-side signals to the other channel. The 3rd channel is for the sub and will always be in mono (and 4 ohms) with your particular amp.

Speakers are either 2, 3, 4, 6, or 8ohms these days, thus there is no such thing as "2ohm stable speakers" only amps are rated for different ohm loads depending on how the speakers are wired up to them.

Given your examples I'd say your right on track - run a set of components in stereo at 4 ohms (140X2), then run the rear speakers off the radio (perfect for rear fill, I'm doing this myself currently) and finally a single sub a 4 ohms (130X1) off the mono channel.

 

The problem with that is you don't have the choice of running either left or right. You have to look on the amp and see what the bridged wires are. For example, if they are Left + and Right - to bridge, then that's your only choice. This is mono, if it was Right + and Left - it would still be mono. Basically you have left and right mixed coming out of both speakers, makes it sound like AM radio, kind of "hollow"

 

Oh I get what your sayin, the guy that i quoted from that other board made it sound like you would just be bridging the front and rear channels so it would still have seperate left and right.

This is probably a really stupid idea but would it be possible to switch the rca inputs around so that the outputs could be bridged left and right? i dont think that even makes sense but just an idea


[Modified by GasHuffer, 10:31 AM 12/19/2002]

 

This is not the suituation if you set the inputs up correctly:

The amp has no clue what Left and right are, they only see and do what they are told....think of the amp as a pair of channels, 1&2 is the first pair while 3 & 4 are the second pair...the two halves of the amp work separately, so make "one amp" right and the other "left" and you are good to go

There are three ways to do this, some are a bit easier then others:

1. The amp has a 2 channel input mode, in this scenario, the amp has a switch on it that allows you to connect the L+R to the first two input channels, and it takes care of the bridging. Unfortunately, I don't think that your MTX has any internal signal distribution, so this option doesn't work.

2. What you need to do is see what type of mode the amp runs in. You may be able to simply plug the right RCA into channel 1's in put and the left channel into channel 3's input and it will be fine.

3. Tis one will work for sure - What you may have to do, is get a pair of Y-cables (one female to 2 male connectors). Split the right RCA to the input for channels 1 and 2, then split the left RCA to the inputs for channels 3 & 4. This way half of the amp is "Right", and the other half is "Left"

Either of these three ways (the third being the most likely) will allow you to run the amp in the manner that you desire. While distortion will increase, I highly doubt that you will be able to hear it...the bridged channels of most amps have a THD of less then 0.1%, so you should be fine. The increase in power is a tradeoff that you will want to take.


[Modified by rcurley55, 6:12 PM 12/19/2002]

 

On MTXs site, it's saying less than 1% THD bridged. 1% is a lot of distortion for fronts. Hell, try it and see what you think, it only takes a few minutes.

 

so it is possible to "fool" the amp by changing around the inputs for the rca's, thats what i was thinkin but i wasnt sure if it was possible.

 

What was I thinking...off by a factor of 10 - it's been a rough morning , but, if you look at the manual, the THD rating for all channels run in stereo is also <1%, so bassically, there is no way of making any comparison between the two ratings....GO MTX!!!

 

I noticed that too. Then on a vendor's site, it showed <.1% for unbridged and <1% for bridged. Could the vendor be correct and MTX made an error, or is MTX scared?????? I don't know, that's why I was suggesting to just try it and see, since it only takes a couple minutes.

 

Go ahead and bridge the two channels to run into each speaker....just take time and level set them properly and all will be fine. Don't get hung up on the numbers...unless you have test equipment ( a scope) you wont really hear the difference in the levels . I used in an install once a thunder 4 channel amp ( the blue grey version...the world champion models) and polk db3065 ( 6.5" comps)...they made such wonderful sounds...great midbass smooth highs.

So go ahead and have fun.

 

k i finally got all my wires run and everything i just need advice on actually bridging this thing, I picked up a set of y splitters so now i need to put the two ends from the right channel of the rca to right rear and right front and the two ends from the left channel on the rca to left rear and left front correct?

now when bridging the outputs does it matter which ones i use, the picture on the bottom of the amp shows how to bridge the front channel or rear channels but not left and right seperate so can someone explain what i do to bridge left and right seperate, sorry this is kinda dumb i just never bridged a 4 channel amp before