M3 or CK2III good for a second project?

[odigg]

Hi,

About 12 years ago I was really into DIY electronics. I built a couple of audio amps based off the LM12 and the LM3886. I used the reference designs from the op-amps datasheets and modified them to suit my needs. In all honestly I didn't understand how the circuits worked, I just learned enough to figure out what parts (resistors, caps) to pick out. As for etching the PCBs, ferric chloride (a substance I'd like to avoid!) was king.

I have not touched any DIY electronic stuff since then. However, I now have a much better understanding of what is going on in circuits. With a good amount of staring and head scratching I could probably figure out what is going on in a schematic (I could do it with the CMOY).

I'd like to build an M3 or perhaps a CK2III. To clean out some of the rust in my brain I'm going to build a CMOY first.

Would an M3 be a good second project? Should I perhaps try something else?

Assuming I can make sense of most of the stuff on the "Initial Setup" page for the M3 at The M³ Stereo Headphone Amplifier should that be enough to get me going?

Thanks.

 

[cotdt]

the CK2III because it is quicker to build, cheaper, and holds its own against the M^3 (I prefer the CK2III myself).

 

[Uncle Erik]

I'd go with the CK2III. Reason being that it has a power supply included on the PCB. You still have to build the power supply, but it's right there and included in the build.

The M^3 requires that you find and use a separate supply, like the STEPS, which I used. There's a couple more things involved.

Also, because it's all on one PCB, it makes casing it a little easier. Fewer holes to drill and less fuss with the layout.

 

[Beefy]

The CK2III looks like a great little inexpensive project. I'm looking at building one soon.

I have already built an M^3 - it was my first DIY audio project. The M^3 is a fair bit more expensive to build and is a bit less 'integrated'..... but the separate power supply is still easier to build than the amp itself. Of the two, the M^3 could ultimately power *much* more demanding headphones.

Another great option to consider is the Millett Hybrid Max. I built one of these very soon after the M^3, and I don't feel that it is as good an amp as my M^3..... but in many ways it was a more interesting and fun build, and cheaper too. Good opportunities for boutique parts, and it just ooozes cool with the tubes.

Of course, why not just build all three?

 

[cotdt]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif Of the two, the M^3 could ultimately power *much* more demanding headphones.

output on both of these amps are about the same according to the specs. maybe you were talking about the Beta22?

 

[odigg]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif Of course, why not just build all three?

My wallet thanks you for that comment.

I was thinking about the Millet Hybrid just to have a tubes complement to a SS amp.

Quote:

Originally Posted by cotdt /img/forum/go_quote.gif output on both of these amps are about the same according to the specs. maybe you were talking about the Beta22?

I was also under the impression that the M3 could produce more power. Isn't it possible to put in different op-amps, up the power past 24V to get more than the M3 specs call for on the AMB site? My primary reason for looking at the M3 was that I was thinking (just thinking) about using it as speaker amp as well.

Since I already have your attention, what's a good multimeter? Fluke stuff is beyond what I'd like to pay right since I'm just starting out again. At the same time I don't want to buy some $20 POS I'm going to replace in a year.

Is an hFE feature important in a multimeter?

 

[Beefy]

Quote:

Originally Posted by cotdt /img/forum/go_quote.gif output on both of these amps are about the same according to the specs. maybe you were talking about the Beta22?

Not at all. The M^3, with its active ground and very high Class A biasing, should be able to drive much more difficult headphones without distortion or dropping out of Class A. The typical STEPS/S11 power supply is also capable of a much larger supply current than the one on-board the CK2III.

But I am eager to build and compare the CK2III though, because I constantly hear how well it punches above its own weight.

Quote:

Originally Posted by odigg /img/forum/go_quote.gif I was thinking about the Millet Hybrid just to have a tubes complement to a SS amp.

Most people don't actually think that the Millett sounds all that tubey anyway. I don't have a full tube amp to compare......

 

[cotdt]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif Not at all. The M^3, with its active ground and very high Class A biasing, should be able to drive much more difficult headphones without distortion or dropping out of Class A. The typical STEPS/S11 power supply is also capable of a much larger supply current than the one on-board the CK2III.

I don't understand. What does Class A biasing have to do with power output? The active ground also has nothing to do with total output. The CK2III can drive efficient speakers just fine, and has MORE power output than most M^3 configurations, though certain M^3 configurations would have slightly more output. Seriously if you are after driving speakers the Beta22 has WAY more output than both of these amps.

also... Class A biasing can be set arbitrarily high on any of these DIY amps.

 

[synaesthetic]

measuring current gain hFe is useful for many projects.

 

[Mazuki]

Have you looked at the Bijou DIY OTL amp?

I would recommend the M^3 over the CKIII simply because you can change opamps in the M^3. That gives you more choice!

 

[Beefy]

Wow, I'm sorry I offended your beloved CK2III

But lets look at this sensibly.

Quote:

Originally Posted by cotdt /img/forum/go_quote.gif I don't understand. What does Class A biasing have to do with power output?

Lower bias will drop out of Class A at high loads.

Quote:

The active ground also has nothing to do with total output.

True, but there is much less chance of distortion from ground pollution at high loads.

Quote:

The CK2III can drive efficient speakers just fine, and has MORE power output than most M^3 configurations

With the standard 7VA transformer, versus a 15 or 25VA STEPS/S11? I don't think so. Voltage =/= power.

Quote:

also... Class A biasing can be set arbitrarily high on any of these DIY amps.

The standard 80mA of the MOSFETs in the M^3 is not good for the BJTs in a CK2III. You would need much larger heatsinks than the board can accomodate.

Look, I'm not bagging the CK2III..... I'm really not. You prefer yours to the M^3, and I'm sure it sounds great. But I don't see any way that anyone can argue it is as powerful as an M^3.

 

[bhjazz]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif Lower bias will drop out of Class A at high loads.

That is correct. Read through the CK2III thread on headwize. You can definitely bias the CK2III at a surprisingly high level. A lot of this depends, obviously, on the output units you choose, and your choice of heatsinks. I'm not totally sure where I left mine.
I can say that this is an incredibly quiet, dynamic amp. It sounds great, correctly reflects upstream components, and gives you what is on the recodgin (good or bad!). For the price, it's a great amp and one I continue to go back to myself. At a meet earlier this year, we compared it to a beta22. It was surprisingly close, although the beta22 had much more extended highs and was a touch more delicate and nuanced. With a few cable swaps and source changes, one could conceivably get them to sound very close.

So to get back on topic, try the CK2III. It's a fairly easy build, the board layout is easy to work with, and there are not a lot of difficult things to do for setup.

 

[odigg]

Quote:

Originally Posted by bhjazz /img/forum/go_quote.gif So to get back on topic, try the CK2III. It's a fairly easy build, the board layout is easy to work with, and there are not a lot of difficult things to do for setup.

Thanks for the info on the CK2III. It's also quite a bit cheaper to build than the M3, so that would be nice if I make a mistake and have to order extra parts.