The JEC 3245 High Power Bridgeable 4 channel car audio amplifier

The JEC 3245 High Power Bridgeable 4 channel car audio amplifier

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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

Physical Appearance

 

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:-

the front face of the jec amplifier showing the knobs and crossover switches Jec amplifier with power connections done to computer power supply

 

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.

Male and female RCA splitters  Female to male RCA splitter 2 ports

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 verdict

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.

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  • cheupe chama

    Great post!
    I run this amp in a large private car with 4 regular pioneer speakers, a pair of twitters and a Sony (Xplod) subwoofer. It is a nice piece, once someone knows how to work with it.
    The settings on the cross over and bass controls are easy to mess up. And it is not easy to intuitively figure out how to operate these settings unless someone has some idea about car amps. It is easy for someone who does not know what they are doing to mess up the settings to the point where they cannot listen to anything on it. Regular speakers produce very annoying crackles when one forgets to adjust mids and highs to go to the regular speakers, and lows to go to the big guy at the back. To the point where a friend of mine having messed up the settings thought I needed new speakers!
    But once someone knows what to do with this amp; well….

    • That’s true cheupe chama, great sounding music lies in the correct crossover settings when using this amp. The speaker types and quality also matter alot

    • Muli

      Thats true… the power is in the settings! The devil is in the dials!!!! I had to train my tech guy on how to tune an amp back in 2004… high levels settings is never equal to good quality. He is now a success story and installs serious sounds around Nairobi. I used to get strangers come up to my car to find out which system i was running that sounded soooo good! I was happy to share and point them in the right direction!
      I do have a big background interest and some training in the theory of sound… acquired from church sound setup, control & management.
      It proved to be a real help….years later! Who knew!

  • Muli

    This is a good amp (mid-end type not pricey with good value for money) especially if your a moderate music junkie (u dont wish your car to sound like a buru buru matatu). It delivers above average crisp sound at moderate volumes. At higher volume levels, it will still give out quite as smooth output thats if you have hi-end powerful speakers. I’m still impressed with it 9 years later – yup! i got mine in 2006 and its still going strong today. It has never broken down once. I am soon upgrading to a new car – and it will be car no.3 and hopefully still counting which this JEC amp will get to sound up.
    I have orig. Pioneer OEM stock speakers in my Toyota Caldina (for each door + matching inbuilt Pioneer OEM tweeters that came with the car, i added Pioneer TS tweeters (2pcs) & 1pc10inch Pioneer Subwoofer – its an old school model that once belonged to a matatu we had in the early to mid 90’s – they were bought back in 1992. I kept 2 of these since (although the 2nd sub is a 12 inch size) & sometimes i do connect them both for more thump). And the thump is a good sounding, deep, rich long range bass that vibrates everything around the car when i pump up the volume! The JEC CA3245 powers all these quite well & doesn’t crash.
    The car dvd/radio i use is a new-gen 2-DIN Pioneer AVH-BT series type + i got the old school Pioneer equalizer EQ-6500 (again from that old matatu).Quite the vintage sound there! oh, i still have somewhere in my storage the old manual type Sony Radio Cassette FM/AM with a loud button & auto reverse that was the hit in most matatus back in the day which still worked – at least the last time i connected it. its for keeps!
    Good stuff.

    • Could not have praised this amp any better Muli.

      • Muli

        I cant vouch for the quality vs longetivity of the same model currently in the market – YOM (year of manufacture) does change quality standards. That said, i got value for my money. Years later i have buyers glee – i didnt spend a lot going for brand heavyweights (i.e. kenwood, alpine, pioneer etc etc) We can still safely get to Mombasa without buying a pricey Kenya Airways ticket. Go figure

        • Very true, vintage items most of the time usually outlive their newer and much more expensive counterparts. Personally I know a guy who had a JEC3244 , 400 Watts Amp that outlived what was meant to replace it, a Boschmann Amp which is proving to be very inefficient due to many breakdowns

      • Muli

        Quick question to you… are you a sound guru???
        I have settled for a Toyota Vanguard 2010 model – midrange specs. I want to tone down on the sound boom, i want to go the “premium sound” way – can you offer advice on the options & choices out there that i could consider?
        Thanks.

        • That’s a very roomy vehicle, you can try reducing the super bass switch to the min or if the mids also produce some bass than change the crossover to HPF. Another solution is to use ported subwoofer enclosures instead of enclosed and sealed speaker boxes.

  • Sirya

    I have the same as shown in the Picture,and i enjoying the music so much,clear Music and good sorrounding.The problem is how to connect it,i only use 2 channels.but the picture above has really helped me alot,am using the transformer for powering it but i need some more assistance from you guys on how to give it the best power input.Thanks

    • Hello Sirya, I have dedicated a whole post to answer your questions. I’m still working on it but once its ready I will post the link here.

      • Sirya

        ——————————————–

  • EARL BRIAN

    Compare jec 3245 and jec 3247 which is better

    • All are good amplifiers but for the guys who love louder music with an even stronger bass, then the 3247 is certainly fir them. If you can get your hands on the JEC 3247 then you would be able to have a dedicated subwoofer channel as well as 4 more additional channels for either mids ot bass. At 1200 watts its more powerful than the JEC3245 by two times.

      • EARL BRIAN

        Thnx for clarifying that, so which would produce deeper/stonger bass: the 200w dedicated sub channel as in JEC 3247 or bridged channel in JEC 3245 for sub

        • All will produce that deep bass if set to 40Hz but thr 3247 will produce much stronger bass

          • EARL BRIAN

            Thnx i bought the JEC 3247 and it works perfectly,

          • Glad to be of help.

          • EARL BRIAN

            I hv pioneer woofer 1000w single voice coil (4ohm) connected to the 200w dedicated sub channel in the JEC3247,i would like to replace that with a 4ohms double voice coil so that if i connect in parallel it becomes 2ohms and as you know JEC3247 is 2ohms stable,QUE: Will i realise any audible difference in bass power(assuming the dvc woofer is also 1000w)

          • Yes you will definitely hear a difference because its going to be louder at 2 ohms since the load will be less. The pioneer speaker will handle the power well since its rated at 300Watts rms.

          • EARL BRIAN

            Can JEC3247 dedicated 200w sub channel handle pioneer 2000w dvc subwoofer

          • A DVC sub is best matched with a monoblock amp. Only a monoblock can drive that sub to its fullest on a 2 ohm setup. The 3247 will work but not as hard

          • EARL BRIAN

            Hi, can a monobock amp rated at 500rms @ 2ohms push the 2000w dvc sub, what monoblock amp can push the 2000w dvc sub to perform best

          • The KENWOOD 1000W MONO block amp (KAC-8106D) can drive that sub comfortably.

          • EARL BRIAN

            Thanks alot for the timely reply

          • BRIAN EARL

            Hi hope ur year has started well.. would like a little advise, am torn between these two mid range speakers: kenwood’s KFC – X712(7*10) & pioneer’s Ts – A2013I (8″) is there much difference in terms of performance considering the kenwood one is abit expensive.
            Which one will give me value for money coz personally i feel the kenwood is abit overpriced though it looks powerful

          • Richard Masila

            U can also try the kenwood 9105d..,
            I have used it with a pioneer 3003wd.,
            It hits lows like crazy..,
            The best recommendation for this sub is a mono with a rating btn 450-900 rms @ 2ohms..,
            Thus this kenwood is the perfect match..,

  • Kemoi Simon

    What’s RMS for JEC 3244? And what subwoofer is recommended here in RMS rating too?

    • Hello Kemoi, the RMS output for the JEC3244 is 400Watts. Any sub with a value higher than 400Watts will do great if its size is 10 inches and above

      • Kemoi Simon

        Hi Dominic, thanks for the reply…I’ve got the first generation JEC 3244 and a friend has advised me to take up Pioneer ready base tube with an RMS rating 300 watts…is this a good pairing?

        • That rating belongs to the amplifier inside the tube, but the speaker may have a higher rating. You can try and connect the JEC 3244 directly to the speaker.

  • Arnold

    hi can a jec 400 watts amp power 4 midrange speakers 2 tweeters and 1 subwoofer? and if yes how do i connect these speakers to the amp to ensure maximum sound quality?

    • First bridge the subwoofer on the rear channels. For the mids either choose the 4 speakers without the tweeters or 2 speakers and 2 tweeters. Connecting all 6 will overload the amplifier. That’s because the JEC 3244 is a 2 ohm stable amplifier (per channel). So connecting two 4 ohm mids in parallel will give you 2 ohms. Adding anything else will lower the 2 ohm impedance recommended therefore damaging the amplifier. Sorry for the late reply.

      • Arnold

        thanks Dom the article really helped great job man

  • Sammy Mwangi

    great post man.
    I bought a boschmann parametric equalizer but i don know actually how to connect directly to my car stereo without needing to use an amplifier

    • All external equalisers need an amplifier. Normally you connect the pre-out ports on a car stereo to the inputs of the equaliser and the outputs to an amplifier. It cant work on an equaliser only

      • Sammy Mwangi

        thanks man, i was thinking that maybe i can connect my sub-speaker to the sub output on my equaliser and am good to go

        • No it doesn’t work that way😊. But its not a must you use an equaliser, an amp hooked straight from your Car stereo will work fine.

          • Sammy Mwangi

            ok thanks alot for your advice. i appreciate it.

  • John

    Hi, John here. I have a JEC CA 3245 that has lost sound on one channel (front speakers & Ts 520), 2nd channel working fine(woofer). Have not done any major troubleshooting. Planning on doing that today, any advice. Left speaker went down, then right and finally the tweeter. Hope its not internal

    • From your description the amp is just fine. Its the speakers you should check

      • John

        Thanks for quick response. Will check today evening and give feedback tomorrow. In case there is no change, I took your number for further diagnosis.Cheers

        • John

          Hi, I’m back again. After realizing that my amp is okay, I hooked up a home theater semi tone unit and sad to say, it died two days after. I checked and confirmed that the front channels are set to HPF and rear is set to LPF. The sub seems to be fine but the front channel seems to be killing my front speakers. Could you be knowing why this is happening? I want to replace the dead speakers with mid ranges but cannot before knowing what is killing them. I was surprised to find that the pioneer tweeter died too…Please debug this headache i am starting to have. Could it be caused by adjusting the equalizer from time to time?

          • Set the bass boost slide switch on the HPF to the lowest level. then try and use bigger speakers foe the mids for example the pioneer 6X9’s TS-A6965S are very good.

          • john

            Thanks, all is well with my sound system now. Pioneer 6*9’s are great…

      • John

        Hi bud,
        you were totally right, i tested the channel with a house speaker and it worked. That means I have some work finding the fault in the wiring. Thanks for your accurate feedback

  • kev sh

    and this thing is resilient!!. i was stuck in a water pool the other day and my passenger just opened the back door to check, only for water to swam my car floor covering everything ( ankle deep so the CA3245 was literally submerged under water and the with radio playing). i could not drain out the water immediately as we were stuck and i couldnt turn off the engine. my CA was hooked to the floor to secure it so it stayed under water for over 30minutes!! on getting home i unwired the CA which was just red on the protect light, opened it up wiped it dry, left it in the sun for 3 hrs, cleaned with home dry cleaner and reconnected.. i was back to business as usual!!!! man cant tell you my relieve, my can floor isnt even completely dry 4 days later yet my CA is chaparing ngoma like nobody’s business!

    • Muli

      Wow! You are one lucky s.o.b !!!! hehehe… don’t try that again esp. now that you opened it up, you have compromised the original sealing.

      You can put in an overide switch to completely power off your amp… just in case!.

  • ATUL DHOKE

    hi,
    i have 1 question u have mentioned 4 channel amlifier right,
    in that u have converted 4 to 2 channel with the help of 2 RCA connectors and after 2 rca it connect mobile /tv/comp via aux cable right ?
    its work ? & sound gettng clear?
    or any disadvantage for amplifier ?