The JEC amplifier is a 4 Channel, Bridgeable (6 ways), 2 ohm stable, High/Low Pass producing Super bass music at 600 Watts and with an inbuilt variable crossover . At least this is what is written on the amplifier itself. Are these mere words or does Japan Electric Company (JEC) put their money where their rice eating mouths is. Let’s find out.
What’s in the Box?
Inside the Brand New Box there is
- The JEC 3245 Amplifier
- A very detailed manual
- 4 self tapping screws with 4 Spring washers
- 2 cables for Red and Black for B+ and Ground connections
- One orange cable for the Remote Turn On
The JEC 3425 Amplifier is a shiny metallic blue in colour with Gold plated Contacts where all electrical contacts to the power and speakers, sub woofers and tweeters are done. The metallic blue colour seems to entice you to give it music and see what is delivered. Underneath the shiny blue colour is the Aluminum chassis that is used as a heat sink.
The Gold plated contacts are there to ensure that all the Mosfets (Amplifying Units) output is fed into the Speakers. There is another thing about the weight, the JEC 3245 Amplifier is a whooping 10Kgs. The greatest proportion of the weight is from the Aluminum Heat sink. The heat sink has fins and grooves so as to maximize the surface area in contact with the air for much better cooling. In fact the Manual does not advise on installing the Amplifier when it’s upside down. The reason is that the hot air will rise into the amplifier and cause thermal shutdown. Does this Amplifier produce so much heat that it warrants such a heavy heat sink? We will find out soon. The following are images from other angles:-
Powering the Amplifier
Since I was testing this Amplifier at home I used a Computer Power Supply Unit rated at 350 Watts. From what I read on the PSU, all the white wires and all the Yellow Wires produce 28 Amps. There is a problem here, the Amplifier has a fuse rating of 40Amperes. What will I do? There is an advantage of using A PSU instead of a transformer because a PSU has the short circuit protection feature built inside. It will automatically shut off when overloaded. This particular DELL PSU operates at much lower temperatures unlike transformers. I used the 3 pin Plug with the PSU because the PSU is covered with bare metal. For more on this you can read How to use a computer power supply safely with your car audio amplifier.
Connecting the Speakers
Wait a minute this is a 4 channel Amp and my cable is only 2 channels. This was my solution to the problem. I bought these two male and female RCA splitters, took them apart and built a Female RCA connector that splits into two male RCA connectors. The photos below speaks for themselves.
My favourite connection mode
The best connection mode that in my opinion utilizes the JEC 3245 Amplifier is the 3 channel stereo mode. In this mode I connected the speakers to the Amplifier as follows. I connected two mid-range speakers with tweeters to the Front Right and Front Left Channels. One Sub woofer bridged across the Rear channel outputs. When the manufacturer says its 2Ohm stable this is what he meant, I can connect two 4Ohm speakers parallel to each other. The final impedance is 2Ohms (Product/Sum). But this is only possible on one channel only. If you bridge a 2Ohm load then you will damage the amplifier.
Giving the Amplifier Music
Before applying any music for the first time, I made sure that all knobs and switches are on the minimum or OFF position.
For the Front Speakers channel 1 and 2, I set the Crossover switch to High Pass. This makes sure that those two speakers will operate fully at the higher frequencies. You can use the HPF (High Pass Filter) Knob to set the crossover frequency from 120Hz to 1.2KHz. The frequencies below the crossover point will be attenuated at 12dB/octave. In layman’s words anything below the set frequency will not be passed on to the speakers.
For the Sub woofer already bridged across the rear channel speaker outputs, this is what I did. I set the Crossover switch to Low Pass. This makes sure that the Sub woofer produces only Bass only (Low frequencies). You can use the LPF (Low Pass Filter) knob to set the crossover frequency from 40Hz to 150Hz. The frequencies above the crossover point in this case will be ignored. After this I set the Super bass switch to the Middle position as per my liking.
Point to note, you cannot use the LPF knob when the switch is set to HPF. You also cannot use the Super bass knob when the crossover switch is set to HPF. The Super bass knob only works then the crossover switch is set to OFF or LPF.
The JEC 3245 Amplifier produces very clean and quality music. The Bridged Subwoofer was so strong that everything in the house was shaking. The Mid range sound complements the bass to satisfy my ears. Even on one channel the music could get very loud. My Semtoni tweeter was so loud that it can make your head ache. This is a warning written on the Manual cautioning users against listening to loud music because it can cause permanent hearing loss.
As for the insufficient power supply, this is how it behaved. There was no voltage drop at all when the amplifier was playing loud music. However the PSU shut down when I selected the crossover switch on the mid-range side to OFF. I will have to buy another PSU and join it to the existing DELL Power supply unit. I will post how to combine two power supplies to power one Amplifier very soon.
In the next few weeks I will post an article on the different connection modes of the JEC 4 channel Amplifier. Let me finish by saying that if you need a car audio installer in Nairobi and its environs’, call or Whatsapp me on +254720093949. I also repair amplifiers and Car Audio Head units.