hello everyone - I have just started to build my first DIY amp. I am completely new to this and although I have a good grounding in general electronics, this is something else again. I am not aiming for anything particularly high end, at least not yet. I've read and re-read everything I can find and understand a lot more than I ever thought possible, mainly due to the extremely knowledgeable people on here. So here's the thing; Where on the MX50SE boards do I pick up the signal ground? And the power ground? There is one blade terminal that says GND - are they both taken from there?
You're help would be invaluable. I can't seem to find the answer to this anywhere.
You're help would be invaluable. I can't seem to find the answer to this anywhere.
I was just looking at the boards at Aliexpress.
Analog signal have separate input.
Seems speaker and power Gnd is at the same terminal.
( AIYIMA 2PCS MX50 SE 100WX2 Dual Channels Audio Power Amplifier Board HiFi Stereo Amplifiers Diy Kit-in Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group )
(btw there is som discussion abt power gnd and speaker gnd shearing or not lokal decopling. Dont worry as you already has boards where power gnd and speaker gnd is at the same terminal.)
That explains a lot - very many thanks for the answer. Bit of a dumb question I know but you have to start somewhere.
Thanks again.
Yes, both speaker gnd and power gnd are the same, so is the signal gnd too. It is possible to add a 'hum breaking resistor' for signal ground to the boards. However how it's done depends on the board versions. The older single sided board is a little bit bigger, and has a small ferrite choke (piece of wire with ferrite arround it, about the size of a resistor) between signal ground and power ground, this can be removed and substituted with a low value resistor (few ohms). The newer boards don't have the choke, so the trace between signal and power ground has to be cut, and resistor inserted. The trace linking them is right next to the power ground connector, on the component side if I remember correctly.
I like these sound from these amps. Great dynamic sound with 8ohm speakers. KEC transistors I did not like so much for treble(harsh), tried some toshiba's and sankens, and they both sounded better in the higher frequencies. There is a version delivered with (fake?) Sankens too, and that sounds nice 'out of the box'.
You should install a trim-pot for bias.
I like these sound from these amps. Great dynamic sound with 8ohm speakers. KEC transistors I did not like so much for treble(harsh), tried some toshiba's and sankens, and they both sounded better in the higher frequencies. There is a version delivered with (fake?) Sankens too, and that sounds nice 'out of the box'.
You should install a trim-pot for bias.
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Normally speaker return/ground connects directly to the power supply, usually the storage capacitor terminals. The speaker current loop is from the power supply +/- through the amp to the speaker and back to the power supply. If you connect the amp input ground to the speaker ground, the result will be instability and oscillations. The amp is connected to the power supply ground for voltage reference only and should there be any speaker current in that wire, it will cause problems. There are several articles on the subject on the internet called "ground loops" aka common ground impedance.
SPEAKER GROUND DOES NOT CONNECT TO THE AMPLIFIER BOARD.
SPEAKER GROUND DOES NOT CONNECT TO THE AMPLIFIER BOARD.
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Massive thanks to all who replied. I have been doing a lot of reading, both here and online generally so a huge amount of research done and I think I've got it straight in my head. Time will tell I guess.
The postman delivered a surprise this morning, it seems I ordered two PSU's. They are identical with a 35A rectifier and 4x10000uf capacitors. So each has total capacitance of 40000uf or 40 milliFarads, unless my maths is totally out. The question I'm mulling over is; as I have two of these, should I use one for each amplifier board, or can they be daisy chained to give 8x10000uf.i.e. can I connect the output of one to the input of the other? Or am I totally over thinking it and save one for the next project. Your sage advice would be greatly appreciated
The postman delivered a surprise this morning, it seems I ordered two PSU's. They are identical with a 35A rectifier and 4x10000uf capacitors. So each has total capacitance of 40000uf or 40 milliFarads, unless my maths is totally out. The question I'm mulling over is; as I have two of these, should I use one for each amplifier board, or can they be daisy chained to give 8x10000uf.i.e. can I connect the output of one to the input of the other? Or am I totally over thinking it and save one for the next project. Your sage advice would be greatly appreciated
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