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140,128 posts
  • New
    Newcomer - Level 1

    I contacted the help desk in order to obtain a replacement power amp for for my BH250, and recieved an invoice indicating the parts that I needed, but so far (4 weeks later) nobody has picked up the phone in order for me to actually order the parts. I have left messages on their answerphone, but I've heard nothing.

    Does anybody actually work there?



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    0 8
  • New
    Newcomer - Level 1

    Hey! I'm really having trouble figuring this out and haven't found articles online related to it. I play e-bass and a Moog synth bass on stage and I need them both to be heard from my bass cab and run via a single cord for the sound guy. For this purpose, I was dreaming about running my e-bass to the "Input" of the amp, and running the Moog synth bass to the insert / effect loop so it would bypass the preamp of the amp. So far I ger both inputs working indivitually but once the effect loop jack is plugged in, the "Input" jack cuts off and signal from it is no longer heard. What might I be missing here?  Thanks!

    0 5
  • New
    Newcomer - Level 1

    I turn it on and it lights up a weird set of lights and does not play. It's stuck in this mode. Clip light, TubeDrive Light, E and A tuner lights, Flat tuner light and Power light are all lit solid. No sound.

    0 2
    • LukeAnderson
      Nigel67 Hi LukeAnderson. Please fill out a Technical Support ticket and we will be able to assist you in getting your unit repaired. This can be done by clicking on the support tab at the top of the page. A new window will open. Scroll down and click on the Technical Support tab and submit a ticket. Many thanks
      • Oct 31
  • New
    Newcomer - Level 1

    Hi , just bought  the above and having problem finding out what lead i need to buy to go from the head to cab . The ones I've bought dont fit!

    Can you help please?




    0 7
  • New
    Newcomer - Level 1

    Hi Lerum Hevitt here all is well but can anyone supply / find / point me in the right direction to help me get myself a schematic //service instructions for my beloved BH 500 amp head please.


    0 11
    • Lerum1
      Dale_M I am afraid we cannot share schematics with non partners we can assist with a non warranty repair via the support tab/Service if you require assistance.
      • Oct 22
    • Lerum1

      Hi Dale thanks for the prompt response but information not what I wanted to hear. Is your goodself an employee/ involved with the service/ repair centre. If so where would I take my BH 500 to. Any help much appreciated. Cheers

      • Oct 23
  • New
    Newcomer - Level 1


    I'd like to plug the XLR balanced output (post eq) of my BQ500 into a mixing desk (Mackie ProFX16v3), but need to enable 48v phantom power of the desk. 

    Does the amp have a built-in safety to allow that? If not, can I use an XRL to 1/4 cable or another workaround? Or do I absololutly need a DI box? 

    Thanks for your help! 



    0 9
    • Alxl29
      Dale_M Many thanks for your question, looking at the Mackie it has a global phantom power which activates all input regardless of needing phantom power or not, I cannot see any reference to any conflict caused in the QSG of the BQ500 so I will have to check with the designers and get back to you.
      • Oct 16
  • New
    Newcomer - Level 1

    Broken Pot 

    0 9
    • Andrewdlevy
      Nigel67 Hi Andrewdlevy. Please submit a spares ticket and a colleague will get back to you with pricing and availability. This can be done by clicking on the support tab at the top of the page. A new window will open. Scroll down and click on the Spare Parts tab and submit a ticket.
      • Sep 27
  • New
    Newcomer - Level 1

    Hi community,

    I want so get a monitor signal from my DI out, and therefore make a cable with XLR to Jack connector. 

    Can I bridge Pin 1&3 safely or will it do any harm to my amp (TC BQ500 bass head)?

    Thanks in advance!


    0 7
    • ID73
      PedroRodrigues Hi ID73 Considering what you are trying to achieve regarding monitoring your signal I would suggest to use the XLR output on the BQ500 to connect it to a device that offers monitoring such as sound card with a XLR input using a D.I. Regarding the asymmetric signal that you referred can you please provide more information on what you are referring to.
      • Sep 14
  • New
    Newcomer - Level 1

    Hi there, 

    I recently purchased the Thrust BQ250 Bass Head. It's rated for 250 watts @ 4 Ω. But my cabinet, like most, is 8 Ω. Now, I know the wattage will decrease significantly since the resistance is doubling, but I also know it's not as simple as cutting the wattage in half. ?

    When you have more resistance the amperage goes up, and watts is volts × amps. So it's not exactly half. As with higher resistance you create more source amps and more source amps by source volts means higher watt. ?

    I've read the manufacturer's product page, specs, user manual, etc... I can't find the information anywhere. I've seen other manufacturer's websites and they'll often print the watts for both 4 Ω and 8 Ω so us bass players don't have to take wild guesses or learn electrical engineering (heck we can barely count to 4 right?) ?

    to;dr: does anyone know how many watts the Thrust BQ250 will output to a cabinet with an impedance of 8 Ω ?

    Thanks very much in advance. ?






    0 44
    • sixtwowaifu
      PedroRodrigues Hi sixtwowaifu, please consider that generally on an amplifier, the current will depend on the speaker impedance (ohms). The higher the speaker impedance (in ohms) the lower the current that can be drawn from the amp, which means less the power.
      Rule will be the following:
      “Doubling speaker impedance halves output power”
      This will result in the following:
      With the unit operating with a 4-ohm speaker, the maximum output power will be 250 watts.
      With an 8-ohm speaker, considering the example above the maximum output power will be 125 watts.
      Thank you
      • Aug 30
    • sixtwowaifu
      maphisjrock1 Hi, looking for a replacement speaker for a BG250/208.
      • Sep 2
  • New
    Newcomer - Level 1

    I was watching a review for the BH800... I assume it is more or less similar to the BH550 with only the wattage differing.

    The reviewer indicated the BH800 was a class D power amp and therefore has a slower attack than other amplifiers.

    I've never heard amps described that way before, can anyone help me understand what it means?

    0 33
    • Jkblight
      PedroRodrigues Hi, Jkblight thank you for your post, please take in to account that there are two basic types of power amplifiers: linear and switch-mode.
      The Class-D amp is a type of switch-mode amplifier that consists of three stages: the input switching stage, the power amplification stage, and the output filter stage.
      A common misconception is that a switching power amplifier is an amplifier with a switching power supply.

      A switching power amplifier utilizes switching technology as a means to amplify the signal, whereas a switching power supply is using switching to provide AC mains power.
      In linear amp designs, the output power transistors amplify the incoming signal analogous to the input signal (same signal only louder).

      In a switching amp, the incoming audio signal modulates the width of an ultrasonic square wave in the output transistors.

      This modulated square wave is then low-pass filtered. The result is the amplified analog signal sent to the speakers. This signal processing is called Pulse Width Modulation or PWM.

      In operation, a switching power amp uses several pairs of power output transistors with each pair operating as switches (transistors can operate either as amplifiers or switches) in a push-pull arrangement. One transistor of each pair turns fully on (saturation) while the other is off, then they alternate.

      One transistor always produces a positive voltage when it is on; the other always produces a negative voltage when it is on. When a transistor acts as an open switch, the current through it is ideally zero.

      When the same transistor acts as a closed switch, the voltage across it is also ideally zero. Whether the switch is open or closed, the power dissipated as heat – current times voltage – would ideally be zero. The result is less power wasted, which means improved efficiency – theoretically 100%.

      Since the output transistors develop almost no current (when off) or no voltage (when on), they produce almost no power wasted as heat. Increased efficiency requires less power from a power supply and smaller or no heat sinks for the amplifier.

      These are important advantages in portable battery-powered equipment. Since the class-D amplifier works in an on/off mode, people mistakenly think that the “D” in class-D means “digital “.

      This is not the case.

      There is no digital coding of the signal. The function of class-D is based on analogue principles.

      Class-D amplifier applications range from battery-powered portable products such as mobile phones, high-end professional amplifiers, musical instruments, and home multimedia systems.

      Please take in to account that I have seen other customer asking information about the same thing and it is difficult to make generalizations, especially when we are referring exclusively to the amps since much is also related to the speakers.
      Nevertheless "fast vs slow" has a lot to do with the bass and it's much more about the transients and the attack.

      Please take in to account that there is no right or wrong or better or worse when it comes to the perception of fast vs slow, as this is a case of perception some Amp may be faster for some and the same Amp may be slower for other.
      • Aug 16
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