Hi, i am looking to buy a 2 channel bridgable amp that is rated and i assume stable at 4ohms.

Now if i get a 4ohm single sub and bridge the the channels (positve from channel 1 & negative from channel 2) will that make the amp run @ 2ohms per channel and therefore be unstable?

How can i make this combo work?

just buy a monoblock.... its much easier and will draw less current

The amp will still be running at 4ohms..... only the power through the 1 combined channel will be increased.


And yes you'd be better off with a monoblock but it wont hurt the 2ch.

monoblock will do the job

I found this in a google search....

"VERY IMPORTANT...
If an amplifier is only rated to drive a 4 ohm minimum load on each of its channels, it WILL fail if you try to drive a 4 ohm bridged mono load. If you have an amplifier rated to drive a 2 ohm stereo load (2 ohms on each channel), it's only going to be able to drive a 4 ohm bridged mono load. A 2 ohm bridged mono load will more than likely destroy the amplifier."

Does this apply to my situation?

Absolutely incorrect, bridging the amp does not use 1 channel both channels are driven into the 1 load so therefore to work out the impedance load of each channel you divide the load by 2 so therefore if the load is 4 ohms each channels is providing the same power as it would if it were driving a 2 ohm load....

Most amps will handle a 4 ohm mono load, if it doesn't don't buy it....

Cheers that made sense.

Hey, I am New to forums, so I don’t now the dedicates involved.
So be patient
Theoretically, A class+A amp that is 25w + 25w that is bridge will put out 100w,
This is because each channel is seeing 2ohms and wanting to put out twice the power.
In practice, this dose not exactly happen, but close is possible.
Things to remember, the more you drive the amp, the more distortion, and it is very bad for your system if it start to clip. Always run your amps below clipping, around ¾ or less, especially if running them bridged
A good amp such as a Rockford can run stereo / mono, running left and right, and a bridged mono for a sub.
Many years ago, I ran 16 speaker, and pulled 128Db of a punch 45 (2 channel), they where the good old days
As outlawxr6 said, If it cant, don’t buy it, stick to quality, it will last, give you versatility, and sound better, Thanks

yeah thanks.

From what i gather when you bridge 2 channels with a 4ohm sub, it is called 4ohm mono, even though the amp 'sees' 2ohms in each channel.

Same effect would be hooking 2 x 4ohm subs on each channel in 'parallel' but only if its 2ohm stereo stable.

Welcome to the forums mate, ahh the old Punch45, I used to use one of those many moons ago, then I progressed to a pair of Punch40 DSM's which were much better amps. I still have a Punch40 IX and a Punch60 IX which is a nice 100 watt combo but now I use bigger Alpine amps now...

You are absolutely correct regarding the clipping, it is THE worst thing around for your speakers, it can burn out tweeters quite easily plus it sounds like garbage.
Though I am note sure about the Class A comment, there has been very few Class A amps used in cars due to the excessive power consumption which is inherent with Class A amplifiers, so most car amps are Class AB and yes 25x2 in a perfect world would equal 1x100 but rarely actually happens, though some go close....

Hey mate, DEFF get a mono if your running two subs or a big massive sub that draws alot of watts....
From experiance I recommend the Alpine V12 amps MR models, very very powerful and competition grade, you'll pay a bit more, but trust me when it comes to sound, dont skimp on it!
- Ash