JBL MPC User Manual
Page 10
9
The tables below are general guidelines on which combinations are acceptable.
MPC200T
Sum of Speaker Taps Connected to AUDIO TRANSFORMER Outputs
0 W
22 W*
44 W**
88 W***
175 W****
Load connected to
2
Ω
✔
✗
✗
✗
✗
LOW IMPEDANCE
4
Ω
✔
✔
✔
✗
✗
output
8
Ω
✔
✔
✔
✔
✗
16
Ω
✔
✔
✔
✔
✗
32
Ω
✔
✔
✔
✔
✗
MPC300T
Sum of Speaker Taps Connected to AUDIO TRANSFORMER Outputs
0 W
31 W*
62 W**
125 W***
250 W****
Load connected to
2
Ω
✔
✗
✗
✗
✗
LOW IMPEDANCE
4
Ω
✔
✔
✔
✗
✗
output
8
Ω
✔
✔
✔
✔
✗
16
Ω
✔
✔
✔
✔
✗
32
Ω
✔
✔
✔
✔
✗
MPC600T
Sum of Speaker Taps Connected to AUDIO TRANSFORMER Outputs
0 W
62 W*
125 W**
250 W***
500 W****
Load connected to
2
Ω
✔
✗
✗
✗
✗
LOW IMPEDANCE
4
Ω
✔
✔
✔
✗
✗
output
8
Ω
✔
✔
✔
✔
✗
16
Ω
✔
✔
✔
✔
✗
32
Ω
✔
✔
✔
✔
✗
* -9 dB from full
** -6 dB from full
*** -3 dB from full
**** full loading
In general, if the CLIP indicator flashes occasionally, the amplifier is approaching its maximum long-term power capacity. If it
is lit about half the time, the amplifier channel will probably go into thermal protection within a few minutes.
2) Computing the minimum low impedance load with a known distributed line load
The formula is:
MinZ = 2 × [RatedLZP/(RatedLZP (Actual HZP × 2))]
MinZ is the minimum load impedance that can be connected to the LOW IMPEDANCE output.
RatedLZP is the maximum rated power of the amplifier into a 2
Ω
load.
ActualHZP is the sum of all the power taps connected to the AUDIO TRANSFORMER output(s).
Example: One channel of an MPC300T has 100 watts of distributed loudspeakers connected to the 70V (or
100V) output. What is the minimum impedance load that can be connected to the LOW IMPEDANCE
output?
MinZ = 2 Ч [450/(450 (100 Ч 2))] = 3.6 ohms
The next-larger common speaker impedance is 4 ohms, so a load of 4 ohms or higher should work satifactorily.
✔
= Acceptable
✘
= Do not use