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The diyAudio First Watt M2x
The diyAudio First Watt M2x
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Old 22nd July 2021, 04:27 AM   #5261
Stanislav is offline Stanislav  Australia
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Originally Posted by Ryssen View Post
Yes but do i bennefit with having a 10000uF elyt after The CaoMx ?
Most definitely.
You need Caps after the CapMx to be your reserve bank, they are the ones to provide juice in peaks. There's a reason why they are called reservoir capacitors.
I would go 10mF-0.1R-10mF (per rail), space permitting.
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Old 24th July 2021, 02:03 PM   #5262
Mark Johnson is offline Mark Johnson  United States
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The diyAudio First Watt M2x
Originally Posted by PaulInWA View Post
... suggestion that it was possible to run the M2x without any daughter board ... ... to remove the daughter board you would just jumper Pin/IO 2 and Pin/IO 4 of the main amp board and leave Pins 3 and 1 unconnected?
Yes, use a 12 inch piece of uninsulated hookup wire to wrap around bolt #2 several times, then three or four figure-eight loops between bolt #2 and bolt #4, then wrap several times around bolt #4. Use painter's tape or masking tape to secure the wraps in place and to avoid accidental short circuits. Leave bolts #1 and #3 unconnected. You could make yourself a little "wiring harness" with two ring terminals and a piece of insulated wire. Slide these over bolts 2 and 4, secure with star washers and hex nuts, done.

Following the advice of wary skepticism, "trust but verify", you could use your continuity tester / buzzer feature of your digital multimeter to prove to yourself that you have correctly identified the four bolts of the daughter card. Unplug the M2x from the mains (obviously) and wait a couple minutes before doing these tests.

STAGE 1 (BLUE): try all four possibilities and find the leads of R1 and R2 which are connected together; your buzzer will tell you. Now find the daughter card bolt which is connected to that point. Your buzzer will tell you. Voila, that is bolt #2. The job is 25% completed!

STAGE 2 (RED): try all possibilities and find out which daughter card bolt is connected to the 6.35 mm (1/4 inch) blade connector P4, where the positive power supply VPOS attaches. Voila, that is bolt #3. The job is 50% completed!

STAGE 3 (GREEN): try all possibilities and find out which daughter card bolt is connected to blade connector P5, where the negative power supply VNEG attaches. Voila, that is bolt #4. The job is now completed! But we are wary skeptics so we will also perform stage 4.

STAGE 4 (YELLOW): Switch your multimeter to the Ohms setting instead of the Beeper setting. Connect one test lead to either end of R5, it doesn't matter which one, and then see which of the four daughter card bolts has less than 30K resistance to R5. Voila, that is bolt #1. The job is now completed.

Attached Images
File Type: png M2X_V1b_MainAmp_Schematic_image.png (100.6 KB, 255 views)
File Type: jpg ring_terminal.jpg (7.7 KB, 254 views)

Last edited by Mark Johnson; 24th July 2021 at 02:09 PM.
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Old 25th July 2021, 04:21 AM   #5263
PaulInWA is offline PaulInWA
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The diyAudio First Watt M2x
Mark, Thanks for those detailed instructions. I actually figured it out by holding the Ishikawa daughter board up to a light and comparing with the schematic.

Since I had extra 220uF Nichicon green sleeve capacitors lying around I actually used that as a jumper. I have no idea how necessary it is but most of the daughter boards seem to include that capacitor as the final component. I guess it is supposed to prevent the core of the Edcor transformer from magnetizing? Anyhow, I tried it both ways and since I couldn't hear a difference with the 220uF I left it in.

Feeding the M2x without a daughter board straight from my DAC didn't permit me to achieve my normal listening levels but I built Wayne's BA2018 and that does provide enough juice to run the M2x. I'm still thinking about the sound of the various input options and I expect to write a post about that soon.

Finally, I had been having persistent problems with a humming noise which I wasn't able to eliminate so I decided to build an external power supply to use with the M2x and perhaps future projects. In the best DIY tradition I used the materials I had lying around to mount the PSU as you can see in the picture. The good news is the M2x is now dead quiet. The bad news is I have no idea if the improvement is because of the distance between the PSU and the Edcor Transformers or the new Antek transformer and PSU board I built.
Attached Images
File Type: jpg M2x No Daughter Board 220uF Jumper.jpg (665.9 KB, 183 views)
File Type: jpg VRDN and Wayne's BA2018.jpg (1.01 MB, 179 views)
File Type: jpg M2x External Power Supply.jpg (896.4 KB, 179 views)
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Old 28th July 2021, 01:52 AM   #5264
Fully Articulated is offline Fully Articulated  New Zealand
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Location: Wellington
Friends, a quick question: is the 4N35-X000 a suitable swap for the standard 4N35?


4N35-X000 Vishay Semiconductors | Mouser New Zealand

The X series appears to be fundamentally the same, but with higher forward & surge current ratings, plus higher output power dissipation.

The regular versions are currently out of stock at Mouser & Digikey.
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