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2nd amp project: M3

post #1 of 26
12/8/09 at 11:39am
Thread Starter 
I recently build a CMOY for a cheap amp on the go. But the building bug bit me and now I want a more challenging project.

So I thought for my second project I'd build a M3... what kind of M3? I havnt got a single clue. This is where you guys come in. What kind of M3 would fit my needs?
  • Headphones: Audio Technica ATH-M50
  • Source: computer/X-fi XtremeMusic (Modded OPAMPS)
  • purpose: Music/gaming/movies (mostly movies and music)
  • Costs: as low as posible (sub $150 USD, prefered in euros )

I've done 3 years of electronics and I can solder quite a bit. But I'm just a hobbiest and not a audiophile.


So what would you guys recomend me? Or is the M3 even the correct choise for me?
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post #2 of 26
12/8/09 at 12:32pm
When you say "what kind of M3," do you mean between the Mini3 and the M^3?

The Mini3 is a great second project, particularly after a CMoy and probably matches your experience level pretty well. There are a few SMD op-amps on it that might be a bit easy for 3 years of soldering, but it's a good step up from the CMoy. AMB also has some great front and end panels and has designed the amp to fit in a Hammond extruded chassis, so if case-work isn't your thing, it can be avoided.

The M^3 has a similar topology, however is a very different beast. It was not designed to be portable, however I seem to recall that it's tough to build for under $150 though I could be wrong. It requires a much more substantial power supply, cheaply done via a TREAD or alternatively an Elpac wall-wart, or with the sigma11. It would also requires some degree of case work unless you're into the bare-PCB look ;-).

From an amplifier perspective, I seem to recall that the ATH-M50 doesn't benefit too greatly from amplification at an input impedance of ~40 ohms (?). If you're just looking for something to build, you might consider building something like the gamma1 DAC. It is a tougher build than a CMoy, but is a delightful DAC that would drive your ATH-M50's quite well.
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post #3 of 26
12/8/09 at 1:31pm
if you have 3 years in electronics, you should be looking at building your own amplifiers based on topologies such as OPAMP --> Buffers etc.

It's cheaper and you get to mess with many options.

Start with the old PIMETA v1.0 Schematic and get to know the various grounding options and buffer options you get.
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post #4 of 26
12/8/09 at 7:09pm
A BOM I created for the CK2III came out at $170CAD. I haven't done the M^3 one yet, but I expect it to be around $220.

That's before getting faceplates done. That'll cost a lot. I'm just debating whether I should leave the faceplates for another time, or just do open-air.
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post #5 of 26
12/10/09 at 1:14am
As much as I got excited for a $150 build (M³ and σ11), my build is approaching $250 (with $50 opamps). Enclosure/panel cost is not included, but I already have one from my leftover Opus DAC.

As for panels, I might decide to do acrylic panels on front and back, or whatever my hardware store (Home Depot) sells. Does acrylic/ABS/polystyrene have static?
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post #6 of 26
12/10/09 at 1:25am
Step 1 : don't spend $50 on opamps, grab 3x AD825, you'll like them.
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post #7 of 26
12/10/09 at 2:43am
I have built an M3 and it is very hard to get under $150 just for good parts, never mind an enclosure or power supply.

The Mini3 is much less, I hear very good things about it and Glass Jar Audio sells a kit for ~$90 including the enclosure. However, there are a few surface mount parts on it, a detail you should take into account.

If you are good at SMD soldering, I would recommend looking at a DAC kit of some sort. I haven't done a whole lot of research into it but I also have headphones that don't benefit a whole lot with an amp and a DAC would probably give you a bit more performance overall.
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post #8 of 26
12/10/09 at 3:12am
Quote:
Originally Posted by FallenAngel View Post
Step 1 : don't spend $50 on opamps, grab 3x AD825, you'll like them.

True words.

Same goes to AD8065, AD744, OPA827.

These are AWESOME chips at their price.
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post #9 of 26
12/10/09 at 3:27am
The AD825 is really, really amazing for the price it commands. It's like a more musical and less neutral version of it AD843 brother.
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post #10 of 26
12/10/09 at 4:14am
Yep, I prefer the AD825 to AD8610 and OPA627 personally. I did grab 3x AD744 and use compensation pin output in the PPAv2, very nice sounding as well.
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post #11 of 26
12/10/09 at 5:15am
Quote:
Originally Posted by FallenAngel View Post
Yep, I prefer the AD825 to AD8610 and OPA627 personally. I did grab 3x AD744 and use compensation pin output in the PPAv2, very nice sounding as well.
Amongst the Analog op-amps, I like the AD797BRZ the best at the moment. I've tried others but keep coming back to this one. They seem to mate well with LT1028 in ground.

Though putting 2x AD825 in signal and AD843 in ground work well too.
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post #12 of 26
12/10/09 at 9:09am
Thread Starter 
So its either a M3 with crap parts to get around $150? I don't really need an enclosure since I'll be letting a friend make me one out of wood. (he needed something to make for a school project) or a mini M3 for around $100?

I'll be using my CMOY for on the go and I wanted a more powerful one at home so in comes the M3. What I really want is a decent amp for around 150 dollar, a fun build and one that I can plug into a wallsocket so I don't need to change batteries around everytime. :P

So if anyone knows a different kind of amp that will fit my needs go ahead and post links to schemetics/parts lists and everything I need to know.
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post #13 of 26
12/10/09 at 9:27am
The Mini3 should probably not be plugged in all the time. I seem to recall the charger circuit provides a constant current into the battery, which for a day or so shouldn't matter, but is not okay being left alone for a few weeks.

You might consider Tangent's PIMETA v2, which while the schematic provides a place to install batteries, the physical layout does not make compromises for them, unlike the Mini3. That said, there's nothing preventing you from leaving the battery removed or the battery charger circuit in the Mini3 unpopulated, though that might affect resale value if you're into that.
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post #14 of 26
12/10/09 at 10:35am
I spent more than $300 to build my M3, and every time had to order parts because I forgot something or had to follow instructions closely. However, I made my power supply with a LM1084, it uses almost no parts and has good regulation. And, the best thing, SOUND IS INCREDIBLY AWSOME!
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post #15 of 26
12/10/09 at 10:45am
Thread Starter 
What about a starving student with some upgraded parts? Is that any good?
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