My first Apex AX20 channel was tested with transformer from a burnt Inter-M L2400 amplifier, as you can see in the picture, this transformer is good to feed the Apex H900. But for my AX 20 stereo amplifier I gona use 1000 VA. About PCB layout, no problem, here is for those wants do de some amplifier. You should star doing the protection first and teste it, than the amplifier, try to avoid component mistakes and dont forget de diferent grounds (in ground and normal ground). And we should say thanks to Miles Boss 
Regards
Regards
Attachments
My first Apex AX20 channel was tested with transformer from a burnt Inter-M L2400 amplifier, as you can see in the picture, this transformer is good to feed the Apex H900. But for my AX 20 stereo amplifier I gona use 1000 VA. About PCB layout, no problem, here is for those wants do de some amplifier. You should star doing the protection first and teste it, than the amplifier, try to avoid component mistakes and dont forget de diferent grounds (in ground and normal ground). And we should say thanks to Miles Boss
Regards
Thank you for pdf files,
Regards
AX17
I have simulated the AX17 schematic in LTSpice, but I obtain poor THD results, 0.18% at 10khz 1V input.
What can be done to increase the performance of this schematic?
Have somebody measured real THD after building this amplifier? what were the results?
See attached files.
Thanks
I have simulated the AX17 schematic in LTSpice, but I obtain poor THD results, 0.18% at 10khz 1V input.
What can be done to increase the performance of this schematic?
Have somebody measured real THD after building this amplifier? what were the results?
See attached files.
Thanks
Attachments
It is posted there, look more carefully.
Here is a new one, with minor changes that lead to 20x less THD, and has -91deg in LoopGain, so it should be perfectly stable (-91 + 180 = 89deg).
Is it correct and better than the original one?
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A few more images: schematic, thd, loopgain.
THD is strongly dependent on the chosen VAS transistors, these
2SA1381/2SC3503 with aprox 5mA collector current obtain the best results in simulator.
I have also prepaired a PCB layout for this AX17 schematic with two pairs of output transistors.
THD is strongly dependent on the chosen VAS transistors, these
2SA1381/2SC3503 with aprox 5mA collector current obtain the best results in simulator.
I have also prepaired a PCB layout for this AX17 schematic with two pairs of output transistors.
Attachments
There is many better VAS transistors than MJE340/350 but MJEs are easy available. Would you share your pcb?
AX17
Here is the PCB for this AX17 schematic with two pairs of output transistors.
It is an extended version of the one firstly designed by AlexMM.
A double check across the schematic should be performed. Note that the components' numbers on my LTSpice schematic do not match the original numbering, please check considering their values only.
I will provide bottom copper layer pdf file in Private Message for those interested in building it.
Any suggestions for improving the PCB and/or schematic are welcome.
Regards
http://i1012.photobucket.com/albums/af241/vlasin_alin/apexAX17_v3_zpsffe74902.png~original
Here is the PCB for this AX17 schematic with two pairs of output transistors.
It is an extended version of the one firstly designed by AlexMM.
A double check across the schematic should be performed. Note that the components' numbers on my LTSpice schematic do not match the original numbering, please check considering their values only.
I will provide bottom copper layer pdf file in Private Message for those interested in building it.
Any suggestions for improving the PCB and/or schematic are welcome.
Regards
http://i1012.photobucket.com/albums/af241/vlasin_alin/apexAX17_v3_zpsffe74902.png~original
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