external speaker output

If your amp has a "Speaker Out" you can simply run this into a speaker cab. Make sure to match the Ohms rating (4 Ohms, 8 Ohms, 16 Ohms... shown on the amp with the speaker Ohms rating.

NEVER run a speaker out into another amp.

However, if your amp has a "Line Out" (completely different from Speaker Out) or "Pre-Amp Out" you can run this into another amplifier.

Yes the speaker out is designed be connected another cabinet. It could be a 1x?, 2x?, or 4x? cabinet with the same Ohm's to match the amp. (? is the speaker size). It can run a 4x12 cabinet.

Joe

Is the external speaker connection ran in series or parallel? If my internal speaker is rated for 8ohms, would the external need to be 8 as well or would it need to be 4 or 16 depending on how it is all connected? Am I making any sense? :D

After posting I realized that maybe the internal speaker is no longer used once an external is connected. Is that the case?

Will it run a cab loud enough to play live and still sound clean?

Lord_Ariez

Usually when you hook up an extra speaker cabinet you will get a slight increase in volume simply because you are pushing more air.

It is hard to explain this, but here goes.

When you run two speakers off an amp they share the watts. So people who are using a 100 Marshall head to power a 4 X 12 cabinet are really only sending 25 watts to each speaker! :cry:

2 identical speakers in close proximity of each other gives you a 3 decibel increase in volume. 12 decibels is perceived as a doubling (twice as loud) of volume. So 3 decibels is perceived as just being a little louder, but not twice as loud as some people assume.

Adding a speaker can decrease your volume. They can cancel certain frequencies. That is why it is good to use an identical speaker if possible.

You have to also understand a speaker's Sensitivity or Efficiency rating. You will see specs like this; 99dB @ 1W/1M. This means this speaker will put out 99 decibels of volume at one meters distance with one watt of power applied. Yep, just ONE WATT.

Also, everytime you double the power to a speaker you get a 3 decibel increase in volume.

So for this 99dB @ 1W/1M speaker....

1 Watt- 99dB
2 Watts- 102dB
4 Watts- 105dB
8 Watts- 108dB
16 Watts- 111dB
32 Watts- 114dB
64 Watts- 117dB
128 Watts- 120db

OK, let's say you have a 120 watt amp. You use it to power this 99dB @ 1W/1M speaker. So it will put out around 120 decibels.

Now you add an additional, identical speaker. But they share the watts. So each gets 60 watts. Thats going to get you about 117 decibels of volume from each. But they are stacked on top of each other so that gets you a 3 decibel gain in volume. YOU ARE BACK TO 120 WATTS :!: :?: :!: :?:

Confusing?? Yep. But that's how it works. But still, adding an additional speaker SOUNDS like more volume (pushing more air around). You will have better coverage and it will sound fuller.

And, one of the easiest and cheapest ways to get more volume is simply replace your speaker with a more efficient speaker. You would get a 6 decibel volume increase just by replacing your 93dB speaker with a 99dB speaker. That's a big increase right there.

And you also want to match speaker sensitivity as close as possible. If one speaker is 99dB @ 1W/1M and you pair it up with a 93dB @ 1W/1M speaker, it will probably sound like the speaker with lesser efficiency is not even on! It will be drowned out by the more efficient speaker.

To answer Crank-N-Jam, it should tell you on the back of your amp which ohm speaker you should use. It is usually wired parallel, but not always.

If you know how to wire, you can configure the ohms yourself. Two 8 ohms speakers in parallel is a 4 ohm load. Two 8 ohms speakers in series is 16 ohms. But don't do that unless you know what you are doing.

Running a speaker with a higher ohms rating does not usually hurt your amp, but your amp will not be able to put out full volume. Ohms is resistance. It is like driving with your foot on the brake.

Running a speaker rated less than the amp specifies CAN damage your amp and quick. There is not enough resistance. Too much current runs through your amp. As a soundman once told me, you are turning your amp into a toaster. Don't do that.

Anyway, hope I haven't caused any confusion here. Try to find a speaker that is the right ohms as specified by the amp, and as close a sensitivity rating to the speaker you have. 8)

Thanks Wes! Didn't mean to hijack the thread, but that's some good info.

When I was a tad younger, I installed car stereos for a bit. So hooking up speakers in parallel and series and such was fairly common. I just needed a refresher. :)

Yes thanks for the great info Wes

You are both welcome.

Sometimes this stuff can be a little confusing. Here is some more to confuse you.

On the average, an amp will put out around 65-70% wattage at 8 ohms to what it puts out at 4 Ohms.

So, you will commonly see specs like this on an amplifier:

100 watts @ 4 Ohms, 70 watts @ 8 ohms.

So, if you run one 8 ohm speaker off this amp it will get 70 watts. Want more watts? Find a 4 ohm speaker and you'll get 100 watts. The 4 ohm speaker presents less resistance to current flow.

Now, you want to hook up two 8 ohms speakers. In parallel the two speakers will present a 4 ohm load to the amp. So now you are getting 100 watts from the amp. The two speakers will share and get 50 watts each.

This stuff will mess with your head when you are trying to figure those SPL (Sound Pressure Level) ratings. SPL is the same as Sensitivity and Efficiency.

So one of the cheapest ways to add more volume to your amp for cheap is simply find a more efficient speaker. A 101 dB @ 1W/1M speaker is going to be 8 decibels louder at any wattage than a 93 dB speaker.

But.... :roll:

You don't ALWAYS want to get a speaker with super-high efficiency ratings. That sensitivity rating is an AVERAGE over all the frequencies.
A speaker that gives you big deep bass may have a lower rating. Bass takes lots of power. And speakers rated 105 dB for instance might be super harsh because it has no bass response. It puts out all high end which doesn't suck up much power. But it will be super loud.

So the speaker sensitivity rating isn't the only thing you should consider. You want a speaker with good bass response, so you might have to get one with a little lower SPL ratings to get this.

Hope all that made sense.