fenderdude said:
Hey everyone one of my power amps reads the following in the manual:
The (output) jacks are wired together in parallel. The internal amplifier of the can deliver its full power output into as little as 2 ohms. The chart below can help determine the total impedance load when connected to various combinations of speakers in parallel. Never connect the mixer to any combination of speakers that have a total impedance of less than 2 ohms!
SPEAKER NUMBER OF TOTAL
IMPEDANCE SPEAKERS IMPEDANCE
4 ohms 2 2 ohms
8 ohms 2 4 ohms
8 ohms 4 2 ohms
16 ohms 2 8 ohms
etc. etc.
Since the output jacks are wired in parallel, does it mean that the speakers must be wired in parallel also for the above chart to be correct or can they be hooked in series and get the same effect? HELP!!! (what if the speakers are wired in "parallel" also? Does that make a difference?) I can't seem to get a straight answer on this...
THANKS!
Fenderdude
Fenderdude,
First a lesson on speaker basics so our discussions can be better understood. (It may help others too.)
Speakers put a load on the amp. To understand this better, think of the amp as a vehicle with an engine and think of the speaker as a trailer full of cargo. The trailer (like dead weight) puts a load on the vehicle and forces it to work harder. The more speakers you connect to a single amp channel, the greater the workload becomes.
This load is measured in Ohms. (Well, it is really a calculated average because the workload is also based on the information being played.) The greater the load, the lower the number given so, 2 ohms represents a heavier load than say 16. If you connect two 8 ohm speakers together (in parallel) they appear to double the load to 4 ohms. This scenario is for a single amp channel only. Each channel is usually independent and can operate at different loads. Hooking one 8 ohm speaker to channel A and another to channel B results in an 8 ohm load for each channel.
This works for speakers wired in parallel. If you hookup speakers in a series configuration, they will have the opposite effect. Two 8 ohm speakers wired in series will result in a 16 ohm load.
When you force the amp to work harder, it also puts out more watts. (Well, until it reaches its limit, anyway.) For example: when an amp has an 8 ohm load attached to it, it may only put out 100 watts on average. But, when you increase the load to 4 ohms, it will now put out closer to 200 watts in response. Two 100 watt 8 ohm speakers can share the wattage and still absorb 200 watts as a team.
Wattage and ohm load are two separate measurements but both should be given equal consideration.
The chart you are viewing is simply trying to help you determine how hard you are making your amp work based on what speakers and how many you have hooked up. Their wording may have confused you. Many amps have the ability to pair two channels together (internally) and behave like one big channel. This is called bridging and it effectively doubles the output wattage. Perhaps they call this "parallel" output. I don't know. Regardless, the same rules apply as far as ohm load.
As a general rule, each amp channel should be double the wattage rating of the speakers you connect. (Yes, this is safe!) You should never force any amp to work at less than 2 ohms. It will probably break down. Most amps work up a sweat when working at less than 4 ohms. 8 ohms seems to be the "comfort zone" for most modern amps. Never go below 4 ohms if amp is bridged. Also consider, if you run an amp at heavier loads, make sure it has plenty of ventilation because it will likely get hotter.
I hope this helps. Good Luck,
RawDepth