Logitech Z340 2.1 Pinout and Reuse
Topics: Audio

Logitech has a large presence in 2.1 systems, where price and appearance dominate.  This sub is designed to trick you, there’s more to it than what meets the eye.

I picked up a used Logitech Z340 2.1, sans the 2.  I got a woofer with no satellites or volume control.

logitech-z340-01
notice in the corner – Mr. Happy Hammer 🙂
logitech-z340-02
8″ subwoofer (4″ speaker + cardboard)

 

Since I don’t have the satellites, this is of no value to me.  And the speaker isn’t of much value either, so I want the amplifier out of this.

 

 

logitech-z340-03

This sub requires a lot of hammering and unscrewing to free the amp.  If you had long needlenose pliers, you could get to the amp without destroying the box.  Otherwise, you will have to rip off the front Revolutionary Subwoofer Panel and smash open the screw-free, super glued box.

 

Logitech Z340 Mini Din Pinout

 

Fortunately, everything here is simple.  The picture of the PCB is where the mini-din connector attaches to the PCB.

 

 

 

logitech-z340-04

You can see where I attached wires to control the subwoofer.  I shorted the standby signal to the 12V out, so it is always on.

The amp will be replacing the Sure amp that broke from my Kicker Sub Build.

 

 

logitech-z340-05

 

Here it is, powered from the 12V rail of an ATX PSU.  Since the Sure amp is gone, the 2nd PSU isn’t used anymore.

 

 

logitech-z340-06

 

And there you have it, a Logitech Z340 that would have surely gone to the dump, repurposed and reused.

 

 

31 thoughts on “Logitech Z340 2.1 Pinout and Reuse

  1. Hi
    i recently purchase the same subwoofer, but without the min din cable. the picture shows the 12v psu powering the amp, does the logitech amp takes 12v power input?

    1. The Z340 takes mains AC in and steps it down to 14.4V, I believe. The chip is a TDA7375, which is actually a car amp. 12V-14.4V is a good range, although the datasheet says it will accept 8V-18V.

      And yes, I removed the transformer, skipped the rectification and smoothing stage, and fed the amp 12V from a psu. You can find where to feed 12V, by tracing to the end of the rectification stage, by the large capacitor.

  2. Hi there, and thanks for sharing your project!
    I have the subwoofer unit but without the other two small speakers. I’ve used the directions in this post to connect the output of the subwoofer to two speakers and the input of the subwoofer to my desktop PC.
    Now, my question is: How do I control the volume of the two speakers using a potentiometer ?

    Thanks!

    1. Hi David,

      The potentiometer will go in between the audio source and ground, like this.

      Since you have a left and right channel, you’ll need a dual-gang pot. This lets one knob control two channels. You’ll wire it like this.

  3. Hi
    I’m trying to make a car sub from this. I followed your instructions and connected the sub out of my car head unit directly to pins 1, 2 and 5(mass). The sub does turn on but all I can get is a very very quiet sound from it (I turned to the max the sub volume on my head unit).
    What do you think is wrong?
    Also where exactly did you solder the +12 and -12V?
    Tnx.

    1. I’d confirm the audio source is good. Try playing music directly from your phone to the amp.

      I soldered the +12V and GND on the underside of the PCB, on the leads of the filtering cap – the enormous one in upper right of the board. The cap has polarity markings. The GND goes to the negative lead of the cap and +12V to the positive lead. https://en.wikipedia.org/wiki/Electrolytic_capacitor#/media/File:Polarity-wet-Al-Elcaps.jpg

      Additionally, check your power line and make sure you are indeed getting +12V. Could be a bad ground, too.

  4. Thanks.
    I’ve already had everything in a way you suggested. I can get a very quiet sound out of it, like 2 on a scale of 10. I remember it being very loud while it was serving as a comp speaker…

    1. In the end it is actually working. Well, it is much quieter than I expected it to be, but if I pump up everything on my head unit to the max it becomes at least usable – well, you can’t expect miracles from a 4W speaker 🙂
      Tnx for this tip.

  5. The Internet is awesome! I’m in the process of almost exactly the same project (z-340 sub hack)! I need to look no further! Thanks a million for all of your efforts.

  6. Hi there. Thanks for making this guide. I’ve unscrewed the panel where the amp is but the cables are so short. So I can’t pull it out. And I’m reluctant to smash up the box. Shall I get a cutter in there, cut the mains and the speaker wire. Then pull amp out. Solder extension leads. ?

    Also am I right in saying I solder two leads to the biggest cap in there?

    I am want to leave the circuit componants alone so I can take out of my car and plug AC in as normal. Obviously making sure my new 12v leads are insulated.

    1. Sorry for the late response, David.

      Yeah, I’d recommend you cut the wires to remove it.

      And correct again, soldering power leads underneath the main cap is ok.

  7. I want to use this amp (Z-340) to power a stand-alone Sony sub. I don’t need the speakers just the sub. I want to run it from my Onkyo receiver’s pre-amp sub output. I can see your wiring but the picture shows a jumble of wires coming from the circuit board that I cannot make out. Which leads do I need to solder to the circuit board to come in from the receiver pre-amp out? The pinout diagram does not show any input to the sub just audio ch1 and audio ch2. I am not an expert and need your help. Thanks so much for sharing your information. It’s a big help!

  8. Gary,
    Here’s my recommendation, assuming your sub out is a single RCA. Solder the outer ground wire of the RCA cable to GND of the Z-340 amp. Solder the inner wire to both the Audio In CH1 and CH2. The reasoning is below:

    Normally, this amp takes a line level stereo channel and does three things with it. First, it amplifies the left side and sends it to the left speaker. Second, it amplifies the right side and sends it to the right speaker. Third, it sums the two signals, sends them through a low pass filter, amplifies that signal and sends it to the subwoofer.

    The sub output of your amp has already applied the sum and low pass filter. No problem. We still feed that signal in to the same Audio In CH1 and CH2 inputs of this amp.

  9. Love this project! Got a couple goodwill purchases this will support. A JVC bookshelf stereo FS-7000 for 14.99 (with the nice hardwood speakers) sounds great, but no bass from tiny speakers. So I picked up a Z-340 sub only for $6.99 and PCBISOLATION provided me with the pinouts I needed. I hope to use a panel mount RCA jack on the amp plate (if there’s room) feeding the signal from the FS-7000 subwoofer output. Hopefully the subwoofer feed is a low level output…
    Do you know if I can/should combine the R/L inputs at my RCA input as to get both channels input to the Amp?
    Any thoughts on my approach
    Suggestions?
    Thanks again, great site!
    Matt

  10. Or maybe two RCA panel jacks (plenty of room) fed by a “Y” cable from the single subwoofer output. That sounds safer.

  11. Hi friend, I need help in the project, so I have to join the wires ch1 ch2 in + gnd, join ch1 ch2 out + gnd, and power the amplifier with 12v after the bridge rectifier? I’m going to use the box in the car, how do I turn it off when I turn off the radio?

    1. Paulo,

      Yes, those connections look correct.

      Having the sub turn on and off with the radio may be more tricky. A relay controlled by some Power_OK or +12V out from the radio may work.

      A simpler solution would be to manually control the sub with a power button.

  12. Can I connect 12v of the car battery straight into the power input of the card ?? where was the transformer connected ??

    1. Paulo,

      If I remember correctly, the big capacitor on the amplifier is connected directly to the 12V rail. You can connect you 12V power to the terminals of this capacitor.

      I’d measure and confirm the voltage underneath that capacitor before hooking up 12V.

  13. I have the z340 with the satellites, however as of last week they longer turn on when operating the switch on one of the pods, normally a led would light up and everything would be fine. checked the wiring and and the plug fuse and everything is in good order. It may just be the internal fuse on the amp but if not is there anyway to use the satellites say with a tv, or do they need to be powered.

  14. Thank you Callahan for you reply

    I have now opened the the sub and managed to get the amp out, the wiring inside the sub for anyone else thinking about it, is a little on the short side, so you may want to extend this before putting the amp back in.

    Tested the output voltages on the pins and these fine, however the plugged in satellites will still not switch on, does anyone here have any ideas of what could be wrong and how to fix it.

    1. Abbey,
      If the amp is outputting the correct voltages, then perhaps the fault is in the satellites or it’s cables.

  15. como puedo identificar los colores y coneccion de un equipo de bosinas para pc marca logitech s200 black

  16. cable que va conectado a siael boffer se estrofio los pines y necesito conectarlos conforme van para no causar un daño

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