GX400 - 400W Audio Amplifier

Discussion in 'Marketplace' started by donpetru, Jun 23, 2014.

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  1. donpetru

    Thread Starter Active Member

    Nov 14, 2008
    186
    25
    Last revision GX400 amplifier is the result of a process of improvement and testing of an amplifier schematic who was wanted in the first to be a simple and compact amplifier, easy to build and with electronic components easy to find. I started polished schematic of the amplifier to be much better than revision no.1.

    It is an audio amplifier that I tested with many types of transistors, including doublet and triplet in the output. As kind Dynacord companies chose to go with transistor amplifiers input its seemingly trivial (since the '80s), see famous series 2N3904/2N3906, I decided at some point, after I test amplifier with 2SC1815/2SA1015, to use 2N3904/2N3906. How legally hearing there was no difference, I said it's not bad to go on these transistors. And the result is very surprising.

    Another important aspect of this amplifier is the fact that, especially in the input circuit, is required to match depending on the current gain of the transistors: N-CH with N-CH and P-CH with P-CH. This leads to easier sorting operation of the transistors, the more so as, if you buy transistors from the same lot, the characteristics of N-CH are very close to the N-CH, respectively P-CH with P-CH. Advantage that should be mentioned even more because there are many electronic hobbyists and professionals who do not have access to a large amount of electronic components to sort them.

    Below I have posted schematics of the amplifier (GX400A - MOSFET version, GX400B -BJT version - both versions use the same PCB). You will notice a method of achieving a bias circuit, which is not the same in the two versions, because they need a bias BJT faster than with vertical MOS.

    I attached a picture below with the PCB amplifier.

    Purchase price of PCBs GX400 are as follows:

    1 pcs. 10 USD / PCB pcs.

    2 pcs. 9.5 USD / PCB pcs.

    If you buy more than 3 pieces: 9 USD / PCB pcs

    The shipping isn't included in the above prices.

    Payment can be made via pay-pal at:

    tehnium[dot]azi@gmail[dot]com

    At this time I have two pieces fully assembled: BJT transistor version and a version with MOSFET transistors; the price of 75 USD / piece - see: GX400_foto2.jpg below.

    I did some tests but in romanian language - I will add a subtitle as soon as possible but most likely next month:
    TEST GX400A - YouTube
    TEST GX400B (inclusiv THD test si calcul Slew rate) - YouTube

    For more details please contact me via private messaging allaboutcircuits.com or via email: donpetru@gmail[dot]com
     
  2. donpetru

    Thread Starter Active Member

    Nov 14, 2008
    186
    25
    Have remained available only 16 pieces PCB GX400.
     
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