https://www.diyaudio.com/community/threads/the-diyaudio-first-watt-m2x.321925/post-7433115
@Mark Johnson first would like to recognize you With Gratitude for Milpitas. Sequiturs for me include working there in Silicon Valley for a medical imaging company in the 90's (nuclear medicine gamma cameras with vacuum tubes in the detectors 3D SPECT image processing via Sun Micro 32 bit RISC computers)
Purpose of this post is a slight potential additional correction to the BOM xls file. Seems to me qty in Row 7 should be 2 not 1:
Also thank you Audiobear in advance for the boards.
Yours Truly,
Jim
@Mark Johnson first would like to recognize you With Gratitude for Milpitas. Sequiturs for me include working there in Silicon Valley for a medical imaging company in the 90's (nuclear medicine gamma cameras with vacuum tubes in the detectors 3D SPECT image processing via Sun Micro 32 bit RISC computers)
Purpose of this post is a slight potential additional correction to the BOM xls file. Seems to me qty in Row 7 should be 2 not 1:
| 7 | R9,R10 | 1 | 499 | 499 ohms (1%) | 1/6 W | 3.4 mm | 3.4 x 1.9 mm or less | 0.55 mm | metal film resistor | 603-MFR-12FTF52-499R |
Also thank you Audiobear in advance for the boards.
Yours Truly,
Jim
@JKiriakis
Great catch, sharp eyes! I probably didn't notice that because I always buy 10, 25, or 100 when I buy inexpensive resistors. It made me chuckle to buy 25 499 ohm 1% resistors when I have a bunch of 500 ohm 1% resistors of the exact same brand and series.According to DHL tracking the boards are in Portland, OR since yesterday. Now we'll see how long it takes to get them across the river to Vancouver,WA. I hope they aren't using "Smart-p-o-s-t" (the reason I wrote it that way is that the spell-checker changes what I type to smartest which it definitely is not).
Nice catch! Yes you need two 499 ohm resistors, so you can populate both R9 and R10.
I checked the EIA standard component value tables (link) and "500" is not listed as a standard value in any of their series, not even the E192 (which has 192 values per decade). The E192 standard values include ... 475 481 487 493 499 505 511 517 523 ... but not 500.
I checked the EIA standard component value tables (link) and "500" is not listed as a standard value in any of their series, not even the E192 (which has 192 values per decade). The E192 standard values include ... 475 481 487 493 499 505 511 517 523 ... but not 500.
You are correct! What I have labeled as 500 are 1/4watt 500K Yageo resistors (MFR-25FTF52-500K). Great reason to check the value of every component before stuffing it in a board.
Those red film capacitors at either end of the VHF amplifier ICs, are not the best choice. Milpitas' Detailed Parts List recommends 0.1uF ceramic capacitors (50V, X7R) in positions C4-C7. Preventing the power supply network from oscillating, is no trivial task with 200 MHz bandwidth opamps.
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Good morning, MarkJohnson!
I understand, that ceramic caps would be the better choice.
Thank you, for this beautiful Milpitas-boards and their excellent sound! I only had minor time to listen to them last night.
But first impressions are great!
Again: thanks for all your efforts to improve the M2X further and further...
Cheers
Dirk
I understand, that ceramic caps would be the better choice.
Thank you, for this beautiful Milpitas-boards and their excellent sound! I only had minor time to listen to them last night.
But first impressions are great!
Again: thanks for all your efforts to improve the M2X further and further...
Cheers
Dirk
Laminated core Edcor interstage transformers are the heart and soul of M2 and its spawn M2x. They are its raison d'etre.
BTW the toroidal power transformer I bought from Antek, and used in my own M2x, has a laminated core too. Its silicon steel laminations are shaped into a toroid.
If you want to experience an M2x without laminated power transformer, I think you may be forced to use ferrite core transformers operated at much higher frequency than 50 Hz. In other words, a switch mode power supply.
BTW the toroidal power transformer I bought from Antek, and used in my own M2x, has a laminated core too. Its silicon steel laminations are shaped into a toroid.
If you want to experience an M2x without laminated power transformer, I think you may be forced to use ferrite core transformers operated at much higher frequency than 50 Hz. In other words, a switch mode power supply.
Mark is (just) pulling your leg that all Xformes used in M2 are laminated - be it signal Edcor or (usual) Donut
now, you can try EI mains iron, but you'll need more luck than with regular Donut, to end without magnetically induced hum in signal iron
shielding - there is really no substitute for thickness, whatever shielding material is
now, you can try EI mains iron, but you'll need more luck than with regular Donut, to end without magnetically induced hum in signal iron
shielding - there is really no substitute for thickness, whatever shielding material is
Hello M2X - Milpitas - builders,
I had some time to listen to the new IPS9 - boards.
My impressions after 1 - 2 hours of more concentrated listening:
What is in my focus - bass control! It offers a very dynamic and controlled (dry) bass. I like this a lot! The rest depends on your speakers...
Highs and mids seem to be very 'clean'. This helps to hear kind of small details in the music. I think these are the results, of a lot of efforts by Mark Johnson,
to filter the rails in front of the OPAmps.
It sounds 'balanced'. No 'loudness-effect'.
All other M2X - buffer - boards are also great! Don't misunderstand me. I wasn't dissapointed by any. Question of taste - for me.
And how your M2X works with your kind of speakers. All builders will have to try on their own...
Cheers
Dirk
I had some time to listen to the new IPS9 - boards.
My impressions after 1 - 2 hours of more concentrated listening:
What is in my focus - bass control! It offers a very dynamic and controlled (dry) bass. I like this a lot! The rest depends on your speakers...
Highs and mids seem to be very 'clean'. This helps to hear kind of small details in the music. I think these are the results, of a lot of efforts by Mark Johnson,
to filter the rails in front of the OPAmps.
It sounds 'balanced'. No 'loudness-effect'.
All other M2X - buffer - boards are also great! Don't misunderstand me. I wasn't dissapointed by any. Question of taste - for me.
And how your M2X works with your kind of speakers. All builders will have to try on their own...
Cheers
Dirk
Nice job, @cubicincher ! Thank you for sharing your listening impressions and evaluation.
So far, so good: nobody has (yet!) reported any backorder or out-of-stock issues with any Milpitas parts. There, I just jinxed myself.
So far, so good: nobody has (yet!) reported any backorder or out-of-stock issues with any Milpitas parts. There, I just jinxed myself.
Hello M2X - Milpitas - builders,
I had some time to listen to the new IPS9 - boards.
My impressions after 1 - 2 hours of more concentrated listening:
What is in my focus - bass control! It offers a very dynamic and controlled (dry) bass. I like this a lot! The rest depends on your speakers...
Highs and mids seem to be very 'clean'. This helps to hear kind of small details in the music. I think these are the results, of a lot of efforts by Mark Johnson,
to filter the rails in front of the OPAmps.
It sounds 'balanced'. No 'loudness-effect'.
All other M2X - buffer - boards are also great! Don't misunderstand me. I wasn't dissapointed by any. Question of taste - for me.
And how your M2X works with your kind of speakers. All builders will have to try on their own...
Cheers
Dirk
How do you like the original "Ishikawa"?
I never built it.
As far as I remember you made special arrangement to do fast switching between input boards (but not as "hot switch")?
Iron-Pre is very popular and the "input board" used there is more or less an Ishikawa.......as far as I can see.....(if output cap is not used).