My favorite Marshall JMP guitar head, a Band of Thieves and new rules to live by..

I will skip all the details that brought me to this point- but i have a new self imposed rule for myself and all staff about the studio amplifiers:
ALWAYS make sure your speaker Impedance (Ohms) match your Power Amp Impedance. NO EXCEPTIONS!!

Forget trying to remember if its ok to use 8ohm on the head side and 4, 8, or 16 on the speaker side. It is a waste of time, energy and more than likely- a good head.

This blog will forever be my reference guide for the details of matching head and cabinet and i scooped the information verbatim from a gentleman nicknamed named Hardtail on this cool website: GuitarMasterClass.net. Thank you Hardtail for the following:

The Ohm is a measure of electrical resistance. Also known as Impedance (do not confuse with "I" below which is the Amperage).

One Ohm = Power / Amperage^2

Or one Ohm is related to the amount of Amps flowing through a circuit at a given Power (watts). Remember that Amps is the "amount of electric charge per second". This is better explained using examples.

Example 1:
100 watt Amp Head with 8 Ohm speaker puts out how many Amps?

Answer:
8 Ohm = 100 watts / (I)^2
Solve for I. I = (100/8)^.5 = 3.5 Amps


Example 2:
100 watt Amp Head with 4 Ohm speaker puts out how many Amps?

Answer:
4 Ohm = 100 watts / (I)^2
Solve for I. I = (100/4)^.5 = 5 Amps

From the above examples we can see that a 4 Ohm jack puts out 5 Amps which is more than the 3.5 Amps from the 8 Ohm jack on a 100 watt Amp head. In fact at 100 watts 4 Ohms puts out 43% more electrical current than the 8 Ohms. This is why you should NEVER plug a 16 Ohm speaker cabinet into an 8 or 4 Ohm jack on your Amp head. But plugging an 8 Ohm speaker cabinet into the 16 Ohm output of your Amp head may not always cause damage right away if at all.

The moral of the story is to make sure your speaker Impedance (Ohms) match your Power Amp Impedance.

BTW-Band of Thieves is the great band that was recently at the studio being produced by Mikki James and engineered by Albert DiFiore and happened to figure in to this learning opportunity..

From the MajorWho Blog:
Band Of Thieves have spent the last couple days with us at MajorWho in our Threshold Music Studios laying down basics for some new material with producer Mikki James and engineer Albert Di Fiore. A lot of great things happening for this band lately and a cool bunch of fellows to boot.. We also learned a thing or two along the way.
This week Band Of Thieves had a song of placed in an episode of The Riches on FX. They've also had music in the ABC series "Greek" and "Parking Wars" on A&E. Congrats on the placements and best of luck!