SPEAKERS & OHMS!!!! Everything you need to know about SP

[CFH Eternal]

Ohms:
A value of electrical resistance. The lower the number, the less resistance. The higher the number, the greater the resistance.


Speakers are rated at certain ohms (or impedance), most commonly, 4, 8, and 16.

Your amplifier is also rated at a certain impedance, or has multiple taps for speaker configurations. It is important that you match
these numbers up.


EXAMPLE --- 8 ohm cabinet--->8 ohm jack on amp
EXAMPLE --- 4 ohm cabinet--->4 ohm jack on amp
EXAMPLE --- 16 ohm cabinet--->16 ohm jack on amp



It is typically safe to mismatch one step higher


EXAMPLE --- 8 ohm cabinet--->4 ohm jack on amp.
EXAMPLE --- 16 ohm cabinet--->8 ohm jack on amp.



Now for the do-not do's.




NEVER EVER hook up a cabinet with a lower ohm rating than the head.

EXAMPLE ---4 ohm cabinet--->8 ohm jack on amp...THIS IS A NO-NO!!!

You will cause your output transformer to overheat, and eventually, it will blow.


NEVER - Turn on a tube amp without a speaker load attached to it. This can cause an output transformer to blow in a short time.

Also, NEVER use instrument cable to hook up a speaker cabinet. The speaker jack can put out a high enough voltage to burn the small wire in instrument cable, thus leaving the amp without a load, and frying the output transformer. ALWAYS use a good heavy speaker cable.



Wiring up multiple speakers.



When wiring speakers, there are three ways to do it

SERIES: one wire from the input jack to the "+" terminal of one speaker, from the "-" terminal of the same speaker to the "+" of the next speaker, last wire from the "-" terminal to the input jack. When wiring speakers in series, multiply the ohms by the number of speakers used.
Also, when one speaker blows, it will cut power to the other speaker as well, leaving both speakers not working.

EXAMPLE: jack------"+ '8ohm' -" ----"+ '8ohm' -" ---jack=16ohms

8x2 = 16



PARALLEL: One wire from the input jack to the "+" terminals of both speakers. Other wire from the input jack to the "-" terminals of both speakers. When wiring speakers in parallel, divide the ohms by the number of speakers used.
In this case, when a speaker blows, the remaining speaker will still work.

EXAMPLE:
jack----"+ '8ohm'"------------ "+'8ohm'"
jack----" - '8ohm'"-------------"- '8ohm'" = 4 ohms

8/2 = 4

This is also the way you will want to hook up multiple cabinets to an amp.

EXAMPLE: (2) 8 ohm cabinets ---->4 ohm jack on amp.
EXAMPLE: (2) 16 ohm cabinets--->8 ohm jack on amp.


SERIES-PARALLEL:

This is the most confusing. The total speaker load will equal the ohms of one speaker. Most commonly used on speaker cabinets that contain 4 speakers. This theory only works with 4 speaker of the same (ohm) rating.
In this case, if a speaker blows, it will take out it's series counterpart, leaving two speakers working, and two not working.


Starting at the upper left speaker, you will run one wire from the input jack to the "+" of that speaker, then from the same terminal to the "+" of the speaker below it.
Then run a wire from the input jack to the "-" of the upper right speaker, then from the same terminal to the "-" of the speaker below it.
Finally, connect the "-" of the upper left speaker to the "+" of the upper right speaker, and the "-" of the lower left speaker to the "+" of the lower right speaker.

I hope this clears up any confusion about speakers and ohms.

[CFH Eternal]

What a waste

[Wrona]

What a waste

No, because there are some uninformed people and some idiots who do not know what the hell they are doing here.

[Pfl?yd]

What a waste

No, because there are some uninformed people and some idiots who do not know what the hell they are doing here.

[croninburg]

When I can afford a head and a cabinet I will refer to this thread