The diyAudio First Watt M2x

Milpitas is definitely a keeper. I’ve run all kinds of tracks through the M2X with it now and some are genuinely startling. Techno/analog synths in particular can sound realllyyy amazing. So many stereos and PAs butcher those.

Anything with a sparkle will shine without being sharp.
 
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I couldn't agree more about the Milpitas IPS and the M2x as a whole. It's an amazing sounding amplifier with more power than I can ever use. I built several of the IPS modules. Each module masterfully designed by Mark Johnson and sound distinctly different.

Built the Ishikawa and the amp sounded beautiful and similar to my F5 and F6. Installed the Austin and the M2x came to life. It reached new highs and lows and was very bright and responsive to the music. Built the Norwood and the music came to life in a totally new and different way. I liked the sound balance in the Norwood which is clean and clear, every instrument appeared in the music, but it lacked the punch of the Austin.

When Mark Johnson posted the Gerber for the Milpitas and I read the write up on it I was instantly curious. I needed to hear this IPS. Built it, installed it and gave listen. I was not prepared for such a dramatic difference. After a good 10 mins of warm up I started listening... and Wow... it surpassed all my expectation. The balance of sound, highs and lows, attack and release, clarity, lack of mud and most importantly it brought the music into the room. I play HD direct digital, streamed music, and analog. Each of them were beyond what I've hear before from the M2x.

The M2x and Milpitas IPS will be playing in my house everyday for many years.

Also... there's been lots of discussion about hum pick up through the Edcor PC600_15K transformer, which in MHO makes this amp stand out from others. I worked on several placement options for power supply parts.
Here's my findings:
1 - Keep the power transformer as far away as possible from the transformer - it's a big hum inducer - some people covered there's I did not.
2 - Next hum inducer was the two rectifiers. Moved them around to find the sweet spot with the least amount of hum. Again keeping them far away from the transformer.
3 - Once the transformer and rectifiers were placed, wire routing made little difference. Optimal wire placement can be seen in the attached picture, but had little affect on overall noise and hum.

The First Watt M2 nominal specification for Noise/hum is 500 µV.
My M2x measurements for noise/hum are > 600 µV - left and > 700 µV - right. Measured on my HP 333A Distortion Analyzer. With it so close to the original spec I was very satisfied.
I got a metal covers for the Edcor transformers, covering them brought the noise down by > 100 µV. Since there is no trace of hum or noise present at my speakers figuring out how to permanently mount the cover seemed to make little sense. So, my Edcors run naked and sound fantastic.

Thanks to Mark Johnson, 6L6, Nelson Pass, ZenMod, and many others for the guidance necessary to build a beautiful sounding Amp.

Carl
 

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