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The diyAudio First Watt M2x
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Old 20th February 2019, 05:59 AM   #1481
batty is offline batty  Australia
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Thanks, that will make life less messy.
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Old 22nd February 2019, 11:03 PM   #1482
BRN is offline BRN  United States
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I just ordered the parts for my M2x boards. Iím going to use the DIYA universal power supply with an Antek 22v transformer and wanted to know if any of the daughter cards would have a problem with a couple extra volts?
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Old 22nd February 2019, 11:45 PM   #1483
BRN is offline BRN  United States
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Correction a 20v transformer
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Old 23rd February 2019, 12:04 AM   #1484
WKCox is offline WKCox  United States
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The diyAudio First Watt M2x
Quote:
Originally Posted by BRN View Post
Correction a 20v transformer
Why 20V instead of specified 18V?
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Old 23rd February 2019, 12:19 AM   #1485
BRN is offline BRN  United States
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Yes
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Old 23rd February 2019, 01:11 AM   #1486
Mark Johnson is offline Mark Johnson  United States
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The diyAudio First Watt M2x
All of the daughter cards are designed for a power supply built with a dual 18VAC transformer. Not a dual 20VAC transformer. That will cause the main amplifier boards to pump about 11% more heat into the heatsinks, which will make the amplifier run hotter than before.

Higher-than-designed-for supply voltage is not good for the daughter cards either. The "Ishikawa" daughter card was designed by Nelson Pass, not me, so he and the many dozens of people who've already built an M2 amplifier (found in the thread "Original M2 schematic") are the ones to ask: Are 20VAC secondaries fatal to an M2 with the Toshiba dual JFET input stage called Ishikawa?

Of the other four daughter cards, higher supply voltage is a credible threat to reduce lifetime and degrade performance. Ranked in order of danger, with #1 being the most dangerous (most likely to fail quickly) and #4 being the least dangerous, I would guess they might be ordered this way
1. Austin. Don't run Austin at higher voltage. If you do you'll regret it.

2. Mountain View. Don't run Mountain View at higher voltage.

3. Tucson. If you use the OPA604 opamp (as called for in the B.O.M.) and the exact Zener diodes in the B.O.M., it will probably survive

4. Norwood. This thing is built like a tank. You can try to hurt it but I don't think you will succeed.
However: it's DIY. Perform whatever experiments you wish, nobody can stop you. Have fun, make videos, gather data, enjoy your hobby. If your amp catches fire, big deal, that's a lot of fun too.

Remember how hilarious the first Iron Man movie was, when Tony Stark's unsuccessful experiments keep setting his home lab on fire? And his butler robot kept blasting him in the face with a fire extinguisher, time after time? That could be you and your safety buddy (wife). Hilarious.
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Old 23rd February 2019, 01:47 AM   #1487
Russellc is offline Russellc  United States
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Quote:
Originally Posted by batty View Post
Dennis is correct, but the holes for this style of RCA are larger, and if the RCA plugs on your cables go on, I suppose it is still functional. They are not designed to mount from the inside. Screws should be on the upper left and lower right. But whatever.

Russellc
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Last edited by Russellc; 23rd February 2019 at 01:49 AM.
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Old 23rd February 2019, 02:03 AM   #1488
6L6 is offline 6L6  United States
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The diyAudio First Watt M2x
Quote:
Originally Posted by Mark Johnson View Post
Are 20VAC secondaries fatal to an M2 with the Toshiba dual JFET input stage called Ishikawa?
Ishikawa will be fine.
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Old 23rd February 2019, 02:50 AM   #1489
BRN is offline BRN  United States
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I will keep the CapMx for now. I have it running at about 21.5v under load with the M2C boards.
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Old 23rd February 2019, 11:49 AM   #1490
cubicincher is offline cubicincher  Germany
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Default M2X experience

Hello M2X-builders,


after 2 weeks of intense listening with the M2X I can say:


This is a beautiful soundmachine!


All the inputboards are fantastic. But each in its own way:


The NORWOOD is a very detailed sounding board. Very little to no hum or
noise hearable. Room information, depth, bass and clear highs are present.
Build it. Also if it is your first experience with SMD-parts-as it was mine!
Use a fine soldertip and tin-lead-solder I will never use lead-free-solder with
SMD-parts again!)
The TUCSON is also OPAmp based. Similar sonic characteristic like the
NORWOOD. Sounds very detailed, clear and without hum or noise. I use the OPA1611 on it at the moment. (OPA604 will be tested, but is in my Whammy at the moment - with adapter, this is a single OPAmp!)
The AUSTIN is based on BJTs. It seems to be be a little bit reduced and not that clear in the highs like NORWOOD and TUCSON. Bass response is very
good. But Austin is noisier. And some audible hum.
The MOUNTAIN VIEW is based on a JFet (J112) combined with a BJT.
I like it a lot - soundwise. Highs are reduced (a little bit) and seem to sound

smoother/silkier than the others. Bass is also deep but sounds different to NORWOOD and TUCSON. But my MOUNTAIN VIEW boards are the
noisiest from all. I prefer this board if I listen to JAZZ or music with focus on VOCALS.
I switch to TUCSON or NORWOOD for ROCK and modern kind of music.
But they all sound fantastic!!!
For me it is a question of taste.
BUILD your M2X and enjoy! I am pretty sure nobody will be dissapointed.
No, you will be surprised.

Cheers
Dirk
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