The diyAudio First Watt M2x

I don’t remember asking for anyone to create a table or list of listening evaluations and cataloguing everyone’s opionions, or a scorecard as to which input builders and listeners found best... I’m not sure why this seems to be such a sore point? Maybe, if this is the case everyone should just start saying “it worked” and go away quietly instead of sharing what they’ve found.

Sorry for asking...
Once again, I find my thought echoed by your reply. I event went as far as asking exactly that: why is it such a taboo to even ask for opinions? At any rate, me too am sorry I asked, though I feel I shouldn't be and this shouldn't be such a controversial question.

If, as Mark points out, it turns out there are as many different opinions as people building the amp, so be it! I still find that healthier than this: "let's never talk about how they sound and wait for everyone to just build their own" approach.

I won't keep asking again though. I prefer not to awaken the dormant beast this arises every time the subject is brought to light.

Rafa.
 
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Please go ahead and talk about what you're hearing, and whether you like it, and what you like the most and the least. Readers will be grateful.

It might turn out to be a very good idea, to also include a few search words somewhere among your posted remarks. Nine months from now, 700 messages from now, you want people and search engines and volunteer gatherers of The Big List, to quickly and easily find your message that gives your listening opinions. Take a few moments to think about what search terms YOU might look for if YOU were trying to find these messages, and be sure your message includes those terms. Post #877 might offer a feeble starting idea or two.
 
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Just got done stuffing all the input boards, was my first SMD, was not as bad as I expected. Had to use a pretty strong lens though :)

If any one is taking notes for future revisions, please make the pads for the zener diodes on the Norwood longer. They are the right size if you are a robot, but just a tad too small to get an iron in there. You can't really make contact with the pad, so you end up heating the leg and hoping it heats the pad under it. The placement of D4 next to R2 is a bit tight considering the D4 pad is a tad undersized.

As for people giving judgement, I say go for it. I already have an opinion about which board will sound best, and I have not even stuffed the amp boards yet. Having others voice their opinions will not cut down on any bias since I think most others will have an opinion about it before they even start soldering.
It might also be nice for people on a tighter budget who can make a better judgement on what board to start with someone with similar gear likes something.
 
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Congratulations on successfully completing your first SMD board! Good on ya. I think if you've got a good circuit board clamp, such as the Aoyue 328 (link 1), a good headband magnifier that resembles (link 2), and a nice pair of tweezers like (link 3), then you are well on your way to success with hand soldered SMD boards.

I don't want to rain on your parade too badly, but you should know that I designed-in the LARGEST widely available SMD packages, the so called "1206" device package, for the components on Norwood. I wanted it to be a newbie friendly introduction to SMD. Most modern electronic board today are built with components in the "0603" package, image below. It's quite a bit smaller. Yes, people do successfully hand-solder 0603 parts. But this requires practice.

Luckily our mentor 6L6 has identified this extremely useful SMD soldering practice kit, at a shockingly low price on Amazon: (link 4). Watch a few SMD soldering videos on YouTube, put together that kit, and now you're a Brown Belt with a soldering iron. Build a couple more SMD boards and you're a Black Belt.

_
 

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Not sure if I'm going to be much help to anyone deciding which input card to build first, but here goes!

I've build and listened to all of the cards, except for the Norwood, and in my opinion they're all worth building and evaluating. Not a bad one in the bunch. To me, differences are slight and the the dominant voice of the amp is set by the Edcor and everything else downstream.

Also, I don't believe I've had enough time to dissect the finer details of each configuration. I started with the Tucson/OPA604, not wanting to part with my precious Toshiba JFETs until verifying that the M2x was work the sacrifice. It was, and I quickly built and installed the Ishikawa daughter board. This combo sounded much richer and warmer than my F5 and I loved the lush sound of strings and overtones of acoustic guitar. I listened to the Ishikawa while working to minimize the amps noise, finally shielding the Edcor and vertically mounting the AnTek close to the front panel. Had this card been the only option, I would be forever happy.

The Mountain View was the card I was looking forward to most, so when all of the parts came in, I quickly swapped out the Ishikawa. The Mountain View is the only card that had a slight power down thump through the speakers, likely due to its single-ended design. I felt there were more harmonics with the Mountain View and I need to get back to audition it further, since I sometimes thought it was giving me too much of a good thing. I also thought the noise (hum) may have been higher with this card, but I forgot to measure. (Current noise baseline is ~350uV with the Austin.)

Lastly, I've had the Austin in for the past several weeks, and it's currently my favorite. For me, a perfect a balance of detail and warmth, favoring the warmth. I know I should get back to auditioning the Mountain View, but the amp sounds so good and I'm too lazy to start messing around with it in my scare free time, choosing to listen to music instead.

In summary, no bad options -- just some slightly different flavors. I could even imagine that, with the subtle differences, a blind test to ID each board would be tricky.

Hope this is of some help to those sitting on the fence!

-Wil
 
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Not sure if I'm going to be much help to anyone deciding which input card to build first, but here goes!

I've build and listened to all of the cards, except for the Norwood, and in my opinion they're all worth building and evaluating. Not a bad one in the bunch. To me, differences are slight and the the dominant voice of the amp is set by the Edcor and everything else downstream.

Also, I don't believe I've had enough time to dissect the finer details of each configuration. I started with the Tucson/OPA604, not wanting to part with my precious Toshiba JFETs until verifying that the M2x was work the sacrifice. It was, and I quickly built and installed the Ishikawa daughter board. This combo sounded much richer and warmer than my F5 and I loved the lush sound of strings and overtones of acoustic guitar. I listened to the Ishikawa while working to minimize the amps noise, finally shielding the Edcor and vertically mounting the AnTek close to the front panel. Had this card been the only option, I would be forever happy.

The Mountain View was the card I was looking forward to most, so when all of the parts came in, I quickly swapped out the Ishikawa. The Mountain View is the only card that had a slight power down thump through the speakers, likely due to its single-ended design. I felt there were more harmonics with the Mountain View and I need to get back to audition it further, since I sometimes thought it was giving me too much of a good thing. I also thought the noise (hum) may have been higher with this card, but I forgot to measure. (Current noise baseline is ~350uV with the Austin.)

Lastly, I've had the Austin in for the past several weeks, and it's currently my favorite. For me, a perfect a balance of detail and warmth, favoring the warmth. I know I should get back to auditioning the Mountain View, but the amp sounds so good and I'm too lazy to start messing around with it in my scare free time, choosing to listen to music instead.

In summary, no bad options -- just some slightly different flavors. I could even imagine that, with the subtle differences, a blind test to ID each board would be tricky.

Hope this is of some help to those sitting on the fence!

-Wil

Thank you for sharing your impressions with the different boards you’ve tried Wil! Greatly appreciated!
 
It would be a good idea if somebody added this to The Big List. Because 9 months from now, it'll be extremely difficult to remember who wrote it, and when it appeared, and in what post number, and what it actually said.

Perhaps those who do share listening impressions could add to their posts something like "#listeningimpressions" as the kids say.
 
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It would be a good idea if somebody added this to The Big List. Because 9 months from now, it'll be extremely difficult to remember who wrote it, and when it appeared, and in what post number, and what it actually said.

I find it interesting that this Big List idea is constantly being put forth. Anyone attempting to build any of the projects in the Pass Labs section of this site are constantly encouraged to read through the entire build thread of the amplifier they would like to build in the hope that the many questions they may have, or problems they may encounter will have been answered and eliminate the same questions over and over, yet the question of sound opionion or impressions shouldn’t some how fall into the same category or requisite reading. The AmpCamp thread is now on post #6590 and growing and again people are still encouraged to read through and search for the information they are looking for before posting. The fact is that the truly interested builders will read through the threads and possibly remember something they’ve come across and revisit the thread again to find it, I know I’ve done this. Why this should be any different for the opinions given about listening impressions is truly a mystery. Maybe we should also consider starting a Big List with all of the “congratulations on a neat build”, and the genuine “Thank You” posts by builders since they are also scattered across every thread for every project because someone might have said “Thanks” instead of “Thank You”, and surely no one would remember the gratitude that someone genuinely shared 9 months ago.

If there’s any Big List that someone should make, it’s a list of all the revisions that may have been made for parts. Unfortunately I, just like you Mark are a busy individual, I have a job, a child to take care of and help with school work, a house to maintain, yadda, yadda, yadda. But when I do have time to myself I read up on the threads of the projects I’m interested in, and I’m sure others will as well without this Big List you would like.
 
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The 30mA version of Moffet Field looks great on a 'scope and runs reliably for days. 1 MHz square wave looks great. I'll post schematic and info tomorrow with another much simpler version at 24mA.

In use, there is a small heatsink on Q1 and both BJT's are Toshiba TC004B which has a higher, flat gain curve than KSC3503 at that current.
 

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Any way to determine the orientation of the octocoupler? There is what appears to be a circle in one corner of the octocoupler. I would guess that this is over Pin 1 and that I am to align this with the notch indication on the circuit board.

Hi Wcwc, yes the circle in the corner should match the end of the screening on the pcb. In the picture below taken from the first page of the thread you can just see the circle you’re referring to and the rectangular notch on the screening below it. It’s a little blurry, hope it helps you out.
 

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Any way to determine the orientation of the octocoupler? There is what appears to be a circle in one corner of the octocoupler. I would guess that this is over Pin 1 and that I am to align this with the notch indication on the circuit board.

Here’s another pic of my completed boards before the output transistors were soldered on. Good luck, and have fun with your build.
 

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I've build and listened to all of the cards, except for the Norwood, and in my opinion they're all worth building and evaluating. Not a bad one in the bunch. To me, differences are slight and the the dominant voice of the amp is set by the Edcor and everything else downstream.

This is very true because I have now heard the M2 without the Edcor and for me, the sound without it and with an Aksa Lender Preamp doing the voltage gain was truly unbelievably more dynamic, clear, and noise free. The noise is now measuring under 100uV and the amp sounds the best that I have heard it sound after nearly 2 years of messing with it.

Here is the M2 with JFETs and Edcor:
610806d1491806355-strange-forest-noise-linear-psu-m2-fft-1khz-8.0v-8ohms-right-channel-no-preamp-linear-psiu-no-cap-mx.png


And here it is, sans Edcor and Aksa Lender doing the voltage gain:
716129d1542499116-aksa-lender-pass-hybrid-m2-alph-m2-amp-alph-m2-experiment-2-85vrms-8ohms-fft-png


I think having a level of third harmonic that is much lower than the second and absence of higher orders is a much more refined and pleasant sound. The overall reduction of THD is less of a concern as the distribution is much more audible. So if you are looking for ways to experiment with the sound, try bypassing the Edcor with a jumper. It’s a simple and reversible mod.
 
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I couldn't agree more with JSA1971. I don't see why every time someone asks about how others feel about each board, the answer is: build them all.

Why can't it be both? Build them all, sure, and all the other variants your heart desire, but why nor share your thoughts about it? Maybe someone says: "I loved the base on input X", and other thinks: "hmmm... I was listening for detail, but didn't try some base tracks, good idea".

Why is it that everyone has to keep their impressions to themselves?

I have asked for this repeatedly and got ONE answer that actually addressed the topic.

If no one will answer, would someone at least tell me why is no one commenting on the merits of each daughter board? It really puzzles me.

Best regards,
Rafa.

I, too have noticed a dearth of these types of comments in not only this thread, but in all the Pass clone threads I've read; ACA, Aleph J, F4.

Accordingly, I have been a bit reluctant to do so myself. My only experience is with the ACA's I built recently, but I could have held forth on my objective observations with a listing of associated equipment, but did not.
Believe I'll get myself over to that thread and get it out there.

Of course, the other equipment in the chain has much impact on the overall result (do I enjoy my music more or less, how does it differ from other combinations of equipment?) but a large enough sample base can make these observations not only useful, but IMHO, add some interest to the overall discussion.

That being said, the technical support available to the diyAudio community is foundational and critical and I very much appreciate those who volunteer it.
 
To XRK971:
It seems to be bit of an improvement without the Edcors. I am building the BA-3 pre so it could be something for me also. How does your schematic look after the bypass? ….you also bypass the "compensation circuit" for the Edcors? …...what about C2?
 
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To XRK971:
It seems to be bit of an improvement without the Edcors. I am building the BA-3 pre so it could be something for me also. How does your schematic look after the bypass? ….you also bypass the "compensation circuit" for the Edcors? …...what about C2?

More details here.

AKSA Lender Pass Hybrid M2 (ALPH-M2) Amp

Basically, I cut the traces after the Edcor and before the JFETs. Then junpered the input to C2 (10uF Silmic II). I then drove the Silmic from a stand-alone Aksa Lender Preamp. But what I did has same effect as schematic in post 1 of above thread.