Ok, I hear you. But if you have only heard the plain vanilla ACA, don't underestimate the difference the premium parts make. Maybe it's the SE sound I like, but to me it's just so special. And even better in near field on a desk. I use it in my office with FR Karlsonator speakers.
I'm a huge ACA fan, but at 5x the power at 8ohm and 8x at 4ohm, M2 is quite another animal, no?
Absolutely. But the request by @BeardyWan was for "the purposes of simplifying a small desktop mini system".
As the happy owner of both an M2 and ACA with Premium Parts, I thought the ACA might be more suitable.
As the happy owner of both an M2 and ACA with Premium Parts, I thought the ACA might be more suitable.
I've run mine on a pair of these with the outputs wired in series. Can't say much more about it other than it did work, no magic smoke. Like the above mentioned, I built the ACA for portability and enjoyed it so much I haven't gotten back around to the "portable" m2.
trying to build 3 way with 4ohm car drivers which ended 3ohm. is it safe to connect M2 without any protector circuit? will it be kaboom?
i have used M2 with minidsp active setup, never used any passive speaker yet.
i have used M2 with minidsp active setup, never used any passive speaker yet.
Apologies because I have been a long long time out of the diy Audio forum community. I just want to say thanks to Mr. Pass and the diy Audio team and share some (oldie) upgrades and photos from my M2 built in 2024. I have a lot of work and it’s difficult to me to be here, but this weekend is holiday and bridge in Italy.
I wanted to build something minimalist, class A, Nelson Pass, zero feedback, good sounding, etc… 😎
Without Mr Pass and the diy Audio forum it would be mission impossible. Thanks again from the bottom of my heart.
So, I have an Aleph 30 clone (di myself) and a lovely Quad from my adolescence totally rebuilt (the only original piece is the main transformer), but wanted to have something class A circuit but less current (power) hungry.
I bought two used (decommissioned) aluminum heatsinks from replaced inverters and also bought 100x20x2 mm aluminum U shaped cheap profile to try a minimalist, brutalist (yeah) and good looking (if succeeded) M2 (the M2 is a very “simple” circuit to be built). A hard task, but being Italian the design flow from our veins…. (I mean, the main thing of Italians is the design so I felt a bit compromised not to let Italy down here in this game -not Sinner ehhhh- …😎)
I got some NOS matched pairs of Toshiba Ishikawa FETs from a trusted ebay seller but after building I realized that needed some tweaks to get zero dc offset to the Edcor transformer input. One channel required to parallel 2,64 ohm to one 10 ohm resistor (yes, 2,64 ohm!!!) and the other channel to parallel 51,8 ohm to one 10 ohm resistor. I guess I bought the wrong matched pair for the current needed. No problem, at the end the FETs works flawlessly with the parallel resistor added, so no worries at all, as I found the precise resistors in one of my old resistor drawer and zero dc offset (only an added resistor on the front pcb). The FETs are original NOS stock, undoubtedly.
The bias current. I measured 0.63 V across the 0,47 resistor for both channels, so I guess I have some 1,34 A in both channels.
I used the aluminum heat sink as part of the mechanical enclosure set up by putting the legs directly on them through flanged nuts.
I bought 0.8 mm copper nude wire to make the circuit connections (the funny part) on two “virgin” perforated boards because wanted to match the heat sink dimensions. Some connections were made with lower diameter wire (like jumper wire) for convenience.
I also decided to try a solid-state switching power source, so bought two (2) MeanWell LRS series having 150 watts each @ 24 volts (LRS-150-24), and they are working in series without any problem at all, and guys, they are ABSOLUTELY QUIET. The mains ground (and chassis ground) is connected through a 10-ohm 5-amp thermistor to a star ground. The PS get hot but until now no failures at all.
I decided to shield the switching PS with some galvanized steel sheets on three sides and to keep them inside the same “enclosure” to minimize RF troublesome, so they are shielded in three sides (up and to the two heatsink sides).
The photos are to show the final design. The top aluminum part is not attached but only “put as it is”. I designed a sliding thing to open they up, but never built it, so the top is free to be taken apart to open the enclosure when using.
Two air open holes are part f the design, and besides to get some dust, they let some air flow inside and make the blue led’s shine in the night.
Some remarks.
My Aleph 30 in my setup has some “low-mid-fat-thing” that emphasizes the voice grain in the mid-low frequencies and make instruments like the tenor sax to have more presence (oh my Gene Ammons sounds so rich…), which is lovely, but the M2 is more realistic I guess.
Also, I think the M2 somehow better filter (perhaps the Edcor transformer) my NOS DAC high freq. “artifacts” and make the highs much enjoyable and clear (only impressions, of course).
Thanks again.
Attachments
@jdamico Well done! That is truly DIY, not "paint by numbers" like most of us do.
Your PCBs remind me of my first Pass build, a B1 buffer. There were no PCB's available and I used plain "Paxolin" sheet and bare copper wire to hook up the components in point-to-point style like you. It worked first time and I'm still enjoying it every day after 8 years.
You are a real DIYer. Respect!
Your PCBs remind me of my first Pass build, a B1 buffer. There were no PCB's available and I used plain "Paxolin" sheet and bare copper wire to hook up the components in point-to-point style like you. It worked first time and I'm still enjoying it every day after 8 years.
You are a real DIYer. Respect!
Many thanks for your kind words, Skylar88
I do like the soldering work and like the point to point soldering thing because is very recreative (being patient like assembling a puzzle) and usually I modify plans on-the-go, but don't have pro mechanical tools to make the enclosure as I would like to do, only a dremel-like hand tool (every hole is M3 for that reason) and some other minor home tools, enough to make the M3 threads by hand and make some minor cut in thin aluminium.
In this case I used the heat-sink as part of the mechanical enclosure, together with U shaped aluminium (10 cm x 2 cm and 2 mm thick). That's it. The final dimensions are very reduced, the ampli is 21,5 cm width, 26,5 cm deep and 25 cm tall without legs. The top aluminium part is not fixed and is "detachable" so the internal blue leds can shine in the night.
Some additional photos.