JBL Control 5 Woofer & Tweeter Frequency Response
The Blue plot above is the Control 5 woofer with the passive Low Pass network. The Red plot is of the tweeter through its High Pass filter. The two drivers cross at 3kHz. This confirms the crossover frequency that’s stated in their datasheet.
JBL Control 5 Frequency Response
The Black plot is the summed response of the woofer and tweeter. This is the Frequency Response of the Control 5 that has never been published. If they did, it would never have qualified as a Studio Recording Monitor. Notice the deep notch at 6kHz. That is caused by the woofer cone breakup peak at 6kHz. Moreover, the response is not flat. From 3kHz upwards, it is about -3dB lower.
Control 5 Toneburst Energy Storage
The Toneburst Energy Storage measurement reveals ringing at 2kHz and 8kHz. These ringing can be seen as bumps in the frequency response plot. The bulk of the ringing is from 5kHz~10kHz. Most of it is attributed to the titanium tweeter but it is exacerbated by the woofer cone breakup peak at 6kHz.
The Control 5 internal passive crossover is shown on the left above. Most notable is a lightbulb sticking out of the circuit board. This is the SK3 light bulb shown in the JBL schematic. This lightbulb is traditionally seen in PA speakers but it is normally installed at the input of the compression driver for protection.
In the case of the Control 5, JBL chose to install the light bulb at the woofer side instead. This brings into question whether they were trying to protect the woofer from damage. In a lame way yes but the reality is more a marketing sleight of hand. There’s no way in hell the 6-1/2″ woofer in the Control 5 can withstand 175 Watts of Pink Noise as specified in their product brochure. At most, 35 Watts. The rest of the power is lost in the SK3 light bulb. Consumers obviously are not aware of this. Since JBL specs clearly states 175 Watts in power handling, it must be loud. That’s where consumers are misled. Most of the power is lost in the light bulb.
The Blue plot above is the impedance of the Control 5. Overall, it presents a friendly load to power amplifiers. The impedance doesn’t dip below 5Ω throughout it’s operating bandwidth. From the plot, we can see the reflex port is tuned to about 55Hz.This is lower than 75Hz, the resonant frequency (Fs) of the woofer.
Part 1 – Thiele & Small Parameters
Note: Unless otherwise stated, all measurements were made with the mic at 36 ins, tweeter axis. Impulse Window=5ms. No smoothing applied.
February 12, 2020Projects