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Old 25th September 2017, 04:05 PM   #61
vitalica is offline vitalica  Europe
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Originally Posted by JPS64 View Post
vvs07 & vitalica boards and parts posted.

JP
I received, ver-very beautifulPCB, thank you!
BR.
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Old 4th October 2017, 01:57 PM   #62
chede is offline chede  Germany
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Quick status update from my side ...

I am still gathering parts:

- new transformer 2x20V 500VA just shipped from Toroidy. I already have a good +/- 19-20V supply in my curent Aleph build, but need to take that to +/- 24-25V.

- Set of Toshibas 2SJ201/2SK1530 won on eBay auction. Waiting for seller to ship.

- Want to use 0R33 source resistors for the Toshibas as per ZenMod recommendation in the thread "Official M2 schematic". Looking for Mundorf MResist MR5 0R33 2%, but selling company is closed for vacation until next week ... Ideally, I had wanted to use MPC74 resistors, but apparently, they are only made in 0R1 - 0R22 - 0R47 - 1R0, not 0R33. And I'm not keen on paralleling them.

On the progress side, yesterday I have measured and paired 2SJ74 / 2SK170. Also as per info on the "Official M2 schematic" thread, I have selected 2SJ74 with about 1 mA higher Idss than 2SK170. One pair is around 10.2 / 9.2 mA, the other around 8.3 / 7.5 mA. So it's 10% difference in each pair.

Major part of work in building my M2 will be heatsink alterations. The case I have and use right now I have built myself with heatsinks 160 mmm x 400 mm, using only frontplate and top from Modushop. So I need to take first one heatsink off and drill / tap it with the new mounting pattern, then remount it, then the other, in order not to disturb the custom alignment of all case parts ...

Regards, Claas
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Old 6th October 2017, 03:49 PM   #63
xrk971 is offline xrk971  United States
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Quote:
On the progress side, yesterday I have measured and paired 2SJ74 / 2SK170. Also as per info on the "Official M2 schematic" thread, I have selected 2SJ74 with about 1 mA higher Idss than 2SK170. One pair is around 10.2 / 9.2 mA, the other around 8.3 / 7.5 mA. So it's 10% difference in each pair.
Beware of the need to magnetically shield the signal transformer on the M2 to get good results. Otherwise, intolerable hum from EMI pickup from the mains power trafo to the small signal trafo. You can spend a lot of time matching FETs etc on M2, but it is all for naught with hum from EMI. Need mu-metal shield box or locate power trafo outside main case, or use SMPS PSU. That's my experience and for me, too much hassle so M2 is now out of the big Class A case for another amp,
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Old 6th October 2017, 07:15 PM   #64
chede is offline chede  Germany
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Quote:
Originally Posted by xrk971 View Post
Beware of the need to magnetically shield the signal transformer on the M2 to get good results.
I have copper foil to make a belly band (Gauss band) for the little Edcor, and a steel Teko 3710 case (JP has designed the PCB to fit this case) for magnetic shielding.
My first GB-img_0139-jpg

Let's see how it goes ...

Best regards,
Claas
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Old 6th October 2017, 09:59 PM   #65
xrk971 is offline xrk971  United States
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Ok that's good you are aware of the issue.
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Old 6th October 2017, 10:33 PM   #66
chede is offline chede  Germany
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Yes, and I am actually very curious about the outcome of the first approach to building the M2.
That's because my Aleph J-ish amp, whose power supply and case I will use, is actually the quietest amp I have so far built, restored, or even used.
I am using 100 dB/W-sensitive speakers, Jericho Horns, as seen in my avatar ...

Best regards,
Claas
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Old 7th October 2017, 10:01 PM   #67
xrk971 is offline xrk971  United States
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I went from M2 to Babelfish J and next will probably be Aleph J (or USSA5 or Apex AA14). If you like your Aleph J, I am not sure you will find happiness chasing an M2. Sorry for the OT posts here we will take it up in M2 thread if there is anymore to talk about.
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Old 15th October 2017, 03:22 PM   #68
chede is offline chede  Germany
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Default M2 Schematic resistor names need swapping

Just an update from my side:

I haven't started my build yet, still waiting for output MOSFETs and source resistors.

I did check the PCB thoroughly yesterday and found that, compared to the most current schematic that I have found (attached here again), the designations of two pairs of resistors need to be swapped to match the PCB.
This would be to swap the names of R114 with R125, and R113 with R122.
Maybe my schematic was outdated ...

All other designations, and all connections appear correct when I trace them.

Again, this is not changing the values, just the names, so that the names on the schematic match the ones on the PCB .

Hope this could avoid some confusion when populating the boards,

all the best, Claas
Attached Images
File Type: jpg M2 JPS64 DIY-NR003 PCB component side.jpg (277.6 KB, 510 views)
File Type: jpg M2 JPS64 DIY-NR003 PCB solder side.jpg (254.7 KB, 510 views)
Attached Files
File Type: pdf PAS_M2-CASCODE_SCH edited che 171015.pdf (30.9 KB, 26 views)
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Old 16th October 2017, 06:42 AM   #69
JPS64 is offline JPS64  Germany
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Thanks Claas, you´re right, corrected, see attachment.

I´m working on a small piece of copper for JFET thermal coupling, more to come.

I´m also working on assembling manuals for PASS HPA, ACA and M2. F6 still pending...

JP
Attached Files
File Type: pdf DIY-NR002_002_SCH.pdf (23.8 KB, 31 views)
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Old 8th November 2017, 07:56 PM   #70
2 picoDumbs is offline 2 picoDumbs  Australia
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Quote:
Originally Posted by brianco View Post
Please remove my name (shown in red) I thought for some reason that this was a M2 POWER SUPPLY board. Apologies.
Brian
This supply pcb can be configured as either the old original Firstwatt powersupply (used in F5, M2 etc) or the newer power supplies that Nelson uses in F7 and F6.
To convert to either supply is just a matter of soldering in a link to convert to the original or leaving out the link to have the new supply.
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