Choosing The Correct Speaker Cabinets - Hartke KILO Mode D'emploi

Choosing the Correct Speaker Cabinets

When choosing a speaker cabinet to use with your Hartke Kilo, there are many specifi-
cations to consider (impedance, power handling, frequency response, etc). While most
specs are pretty straight forward, many people have difficulty understanding imped-
ance. Basically, impedance is the amount of current that will flow through a speaker
at a certain voltage. It is measured in Ohms. The actual impedance of a speaker is not
constant across all frequencies. So, for convenience we use the term "nominal imped-
ance", which refers to the impedance that a speaker presents to an amplifier at a refer-
ence frequency.
A typical speaker has an impedance rating of 4, 8, or 16 Ohms. Generally, the lower the
impedance of a speaker, the more power will be developed by a given amplifier. For
example, a 4 Ohm speaker will extract more power from your amplifier than an 8 Ohm
speaker. If you connect a speaker with an impedance lower than the rating of the am-
plifier's output, the amplifier can overheat and damage the power output section. It is
important to learn how to connect multiple speaker cabinets safely without damaging
the speakers or the amplifier in this way.
As a general rule, amplifier speaker output jacks and speaker cabinet input jacks are
considered "parallel" connections, and will follow the rules described in this section.
When speakers are connected in parallel, the impedance is reduced. The formula to
calculate the total impedance of your speaker system is:
1/R = 1/R + 1/R + 1/R
t 1 2
If all speakers have the same impedance, the total impedance will be equal to the
impedance of a single speaker divided by the total number of speakers. For example, if
you have two 4 Ohm speakers connected in parallel, the total impedance is 4 divided
by 2, or 2 Ohms. You must be careful when connecting speakers in parallel to an
amplifier. The impedance can quickly fall below safe levels. This is especially true when
connecting speakers in parallel to a bridged amplifier.
The Hartke Kilo has two independent amplifiers capable of 500 watts, to which you
can connect speakers with a minimum impedance of 2 Ohms. The amplifiers can be
bridged together to deliver 1000 watts of power to a minimum 4 Ohm speaker load.
When choosing speakers, make sure that they can match or exceed the output
power of the amplifier, or you can damage the speakers.
16
+ ... 1/R . Where "R" is the impedance of a speaker cabinet.
3 n
Typical Impedance Calculations
16Ω + 16Ω =
8Ω + 16Ω = 5.3Ω
8Ω +
8Ω + 16Ω +
16Ω + 16Ω +
4Ω +
4Ω +
8Ω
8Ω = 4Ω
16Ω =
16Ω + 16Ω = 4Ω
8Ω = 2.7Ω
4Ω = 2Ω
4Ω