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Melbourne Daughterboard for M2X
Melbourne Daughterboard for M2X
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Old 7th February 2019, 07:06 PM   #1
xrk971 is offline xrk971  United States
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Join Date: Oct 2012
Location: Metro DC area
Melbourne Daughterboard for M2X
Default Melbourne Daughterboard for M2X

This is a GB for the Melbourne daughterboard (DB) for the Mark Johnson (Pass) M2X amplifier. It will follow the standard M2X hole pattern for electrical connections and have an additional pin for GND. This is needed because this DB can be configured to have gain rather than a 0dB buffer. More info on this board can be found in this thread, and also here in the Melbourne HPA thread.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Basically it is an Aksa-Lender preamp but redesigned for dual rails of +/-24v with a built in CRCRC filter to clean up the supplies a bit. Also has an upgraded mu-follower output stage for lower distortion in order to drive the 600ohm impedance Edcor transformer. It can be DC coupled, but probably best to leave the C2 AC-coupling cap (on the M2X) in place to avoid saturation of the Edcor.

The board measures 70mm x 35mm x 1.6mm with single thickness copper and ENIG finish in blue.

The Melbourne can also be used as an excellent standalone preamp or even as a headphone amplifier. Indeed, I have used it for both and it works great on all accounts. Currently, it is driving my MOAMOFO:
Click the image to open in full size.

Here it is HPA:
Click the image to open in full size.

Note that above photos shown with v1 of the board which had incorrect M2X pinout holes, now fixed on v2.

Prices will probably be about $20/pair depending on how much interest there is. Shipping in US is $5 and $10 to Canada, and $15 everywhere else.

Please add your name to the list below with qnty desired and country shipping to.

I want to thank JPS64 for doing such a fantastic job on the layout!

Cheers,
X

Top silkscreen, schematic, and parts list below.

EDIT Feb 11, 2019: Motherboard for stand-alone Melbourne as preamp or HPA in progress.
Melbourne Daughterboard for M2X-mel-mb-3d-render-01-png
Attached Files
File Type: pdf MELBOURNE-THT_PBA-TOP_002b.pdf (25.8 KB, 31 views)
File Type: pdf MELBOURNE-THT_SCH_002b.pdf (23.8 KB, 49 views)
File Type: txt Melbourne-THv2-Parts-List.txt (1.9 KB, 27 views)
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Last edited by xrk971; 11th February 2019 at 04:17 PM.
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Old 7th February 2019, 07:37 PM   #2
twitchie is offline twitchie  Canada
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Melbourne Daughterboard for M2X
twitchie (2) pair - Canada
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Old 7th February 2019, 08:08 PM   #3
spind is offline spind  Canada
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Join Date: Feb 2003
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Melbourne Daughterboard for M2X
twitchie (2) pair - Canada
spind (2) pair - Canada
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Old 7th February 2019, 09:19 PM   #4
Russellc is offline Russellc  United States
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Join Date: Mar 2003
Location: midwest
Melbourne Daughterboard for M2X
twitchie (2) pair - Canada
spind (2) pair - Canada
Russellc (2) pair-USA
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Old 7th February 2019, 10:08 PM   #5
batty is offline batty  Australia
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Quote:
Originally Posted by Russellc View Post
twitchie (2) pair - Canada
spind (2) pair - Canada
Russellc (2) pair-USA
Batty (2) Pair - Australia
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Old 7th February 2019, 10:47 PM   #6
TungstenAudio is offline TungstenAudio  United States
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TungstenAudio (2) pair - USA
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Old 8th February 2019, 01:05 AM   #7
xrk971 is offline xrk971  United States
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Melbourne Daughterboard for M2X
Just a clarification - you guys mean a pair or 2 boards, and not 2 pairs (4 boards)?
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Old 8th February 2019, 02:25 AM   #8
TungstenAudio is offline TungstenAudio  United States
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I was going for two pair, or 4 boards.
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Old 8th February 2019, 02:36 AM   #9
twitchie is offline twitchie  Canada
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Join Date: Jul 2004
Location: Toronto
Melbourne Daughterboard for M2X
twitchie (4) boards - Canada
spind (4) boards - Canada
Russellc (4) boards -USA
batty (4) boards - Australia
TungstenAudio (4) boards - USA

@spind/Russelc/batty please confirm that you want 4 boards and not 2 boards
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Old 8th February 2019, 03:32 AM   #10
Russellc is offline Russellc  United States
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Join Date: Mar 2003
Location: midwest
Melbourne Daughterboard for M2X
Yes, 4 boards, 2 stereo sets

Russellc
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Pass B-1 preamp, Pass BA3 preamp, Pass F-5 Amp, Pass F-6 Amp, Pass BA-3 Amp, Pass M-2 amp, Pass Aleph J amp, Pass Pearl 2 Phono pre Tekton Enzo, Altec A7, Econowave JBL 2235H & B&C CD
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