silly mono amp question

[icu400]

I use a sony mono sub amp. It is of course bridged on the inside, but it has 2 sets of speaker outputs. A guy at a shop is trying to tell me that if I have 2 subs hooked up to it, they are getting half power, is this true? I have always thought that with the 2 sets of outputs, each set got equal power....

 

[Redrig]

Ill take a stab at this. Are you sure its a mono amp? I always thought a mono amp didnt have to channels as you are explaning. If it isnt a mono amp and you are using both channels individually than yes you are getting half power.

 

[icu400]

Yes it is a mono amp. I assume by that statement you are saying that a stereo amp gets half power when using each channel versus bridging the two into one channel. I suppose that is correct, you do get twice as much when it is bridged, but my amp is bridged on the inside (hence one channel). And it has 2 outputs. I am not sure how it works, but look at it this way, if I was getting half power, and that means my current subs would be getting 125 watts (rated at 300) and I seriously doubt that these things (even if they are sony) would sound half as good as they do now with that low of power (amp rated at 250 watts)

 

[Redrig]

Ok I learned something new. A mono amp does have 2 outputs. I must have misunderstood what mono amp meant. So that leaves us to what I said before, if each sub is using a seperate output then your losing power. You need to bridge the outputs to one channel and wire your subs in parallel.

 

[kalel33]

Ive never seen a 2 channel mono amp either

 

[icu400]

Ok, I kinda get it now. Here is the deal: the amps speaker outputs are wired in parallel internally.

So does that mean that if I have 2 4ohm speakers hooked up, 1 to each output, then the amp is delivering the power of a 2 ohm load since the outputs are wired in parallel? Because that would mean double the power....

 

[Jason94sport]

A mono amp has only 1 output channel. Hence the term mono.

Any 2 channel stereo amp can be bridged so it can use the power from each channel & run a big watt single rated channel.

Example:

A 2 channel amp is rated at 100W/per channel
Bridge that amp to a single channel & you have 200W into 1 speaker.

So if you have a 2 channel amp bridged into 1 channel(sounds to me this is what your have) you will get more power into 1 speaker.

If you run the amp in regular stereo mode you can now run 2 speakers, but each speaker will have 1/2 the power the single bridged channel did.

Example:

200W for 1 speaker bridged
In stereo 2 channel 100W for each channel

Go here & download a good manual on the subject:
http://www.crutchfield.com/download/S-bWlWllmldoM/CarGuide.html

 

[MONMIX]

How many inputs does the amp have ?
A mono amp with two outs makes no sence.

 

[Cartman]

MTX does the same thing, there are 2 sets of speaker terminals on the amp and they are connected together inside the amp. It allows for cleaner wiring.

If you have one sub wired at 4 ohms and it is getting 250 watts wiring a 2nd sub to the other set of terminals would give 250 watts to EACH sub because the impendance that the amp sees is now 2 ohms.

 

[icu400]

Thanks cartman, that makes perfect sense

 

[NusenseSD]

How many inputs does the amp have ?
A mono amp with two outs makes no sence.

JL Audio does this also to make hooking up speakers easy.. Basically they take the single output and run 2 peaker terminals off of it.. This is a picture of a JL 500.1 which is a mono amp..

Basically its done so you don't have to cram 2 speaker wires into one terminal.. So yes there are mono amps out there with dual speaker outs..

 

[03ExplorerSPT]

My JBL has 2 outs on it also. I never understood that until this thread.

 

[icu400]

So yeah, now that I know what is the deal, I will sum it up.

Both of my subs are wired for 4 ohms, one to each set of outputs. This is in effect like wiring them in parallel inside the amp. The formula for resistance in parallel is: 1/r=1/4(for the resistance of each part) + 1/4

That means that r=2 ohms, so the total impedance of that wiring is 2 ohms, meaning the amp delivers 500 watts of power. However, since this system has 2 subs, that 500 is divided by 2, meaning that indeed the power is cut in half, but I am still getting the full 250 for each driver.

Pretty weird, but it means that I don't have to run wires all over the place I suppose. Thanks to all that helped me figure that out, and I hope I was not the only one helped by this

 

[MONMIX]

Okay so we are talkin' one out put source with two connection points.
Right ?
Meaning, out put connection A and B are hearing the exact same thing at the exact same level.
Right ?
I can work with that.

 

[icu400]

Yeah, thats basically it.

Think of it this way: on a "normal" mono amp that only has 1 set of outputs, you would have to run wires between the subs to wire them in parallel. However, my amp and the mtx and JL ones listed as well, basically put those extra wires inside the amp, so that it looks cleaner. If that is easier to vision, look at it that way.

Since this is the only mono amp I have ever owned, I never thought about it really until it was mentioned to me, but I can see how others who have never had one of "these" would not think that way either. I think this thread has been a wake up call to many of us.