Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Pass Labs This forum is dedicated to Pass Labs discussion.

The diyAudio First Watt M2x
The diyAudio First Watt M2x
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 15th October 2018, 12:46 PM   #691
WKCox is offline WKCox  United States
diyAudio Member
 
WKCox's Avatar
 
Join Date: Mar 2004
Location: Verona, WI
The diyAudio First Watt M2x
Quote:
Originally Posted by MEPER View Post
Where do you get "cheap" mu-metal?

It may also be possible to use mu-metal tape. I know this company sell it (but expensive). But tape may be easier to "apply":
3200 to 4700 - EMI shielding tape | Holland Shielding Systems BV

May also be possible to find it on ebay.

So the problem is that the transformer act as a "pickup" and pick up som stray fields from PSU?

Think my solution will be so isolate the M2X boards from the PSU. If hum is a general problem with this amp the building guide maybe should be updated on how to avoid it in first place?
I don't think that there is any "cheap" Mu-Metal. I paid $122 for a 2' x 4" x 0.01" piece of Mu-Metal foil from McMaster Carr.

Before the Mu-Metal shielding, I was seeing noise levels of around the 500 uV, which is the First Watt specification for the production version. After shielding, I measure around 100 uV (0.1 mV), which is quite an improvement and the limit of my test equipment.

I'm sure there will be more feedback for builders regarding shielding techniques as more people build the M2x.
Attached Images
File Type: jpg IMG_2444a_small.jpg (352.4 KB, 428 views)
__________________
Pass F5, Pass M2x, Pass ACA, Audio Research ST-70-C3, Dynaco ST-35, Audio Electronic Supply SE-1, Elekit TU-8500, Hagerman Bugle, Scan-Speak Solist MTM, Selah SA-1, Seas Loki, Cavalli eXStatA, Millett Hybrid MAX, Millett Hybrid MiniMAX
  Reply With Quote
Old 15th October 2018, 12:57 PM   #692
WKCox is offline WKCox  United States
diyAudio Member
 
WKCox's Avatar
 
Join Date: Mar 2004
Location: Verona, WI
The diyAudio First Watt M2x
One more thing: To reduce hum, try to separate the power transformer from the input transformer as far as possible. A deeper case than I used would be better to maximize the distance.
Attached Images
File Type: jpg IMG_2400a small.jpg (472.4 KB, 426 views)
__________________
Pass F5, Pass M2x, Pass ACA, Audio Research ST-70-C3, Dynaco ST-35, Audio Electronic Supply SE-1, Elekit TU-8500, Hagerman Bugle, Scan-Speak Solist MTM, Selah SA-1, Seas Loki, Cavalli eXStatA, Millett Hybrid MAX, Millett Hybrid MiniMAX

Last edited by WKCox; 15th October 2018 at 01:04 PM.
  Reply With Quote
Old 15th October 2018, 01:13 PM   #693
JSA1971 is offline JSA1971  Canada
diyAudio Member
 
Join Date: Jan 2016
Location: North Toronto
The diyAudio First Watt M2x
Quote:
Originally Posted by WKCox View Post
One more thing: To reduce hum, try to separate the power transformer from the input transformer as far as possible. A deeper case than I used would be better to maximize the distance.
Nice neat build! Where did you get the mounting bracket for the toroid? Or is it a DIY homemade bracket? If so, what metal did you use?

Thanks!
  Reply With Quote
Old 15th October 2018, 01:35 PM   #694
WKCox is offline WKCox  United States
diyAudio Member
 
WKCox's Avatar
 
Join Date: Mar 2004
Location: Verona, WI
The diyAudio First Watt M2x
Quote:
Originally Posted by JSA1971 View Post
Nice neat build! Where did you get the mounting bracket for the toroid? Or is it a DIY homemade bracket? If so, what metal did you use?

Thanks!
Bracket is an L-300 from Toroid Corporation. The L-300 is a good fit for the AnTek AS-3218. I have also used the L-625 L-bracket which is a good fit for the Antek AS-4218.
__________________
Pass F5, Pass M2x, Pass ACA, Audio Research ST-70-C3, Dynaco ST-35, Audio Electronic Supply SE-1, Elekit TU-8500, Hagerman Bugle, Scan-Speak Solist MTM, Selah SA-1, Seas Loki, Cavalli eXStatA, Millett Hybrid MAX, Millett Hybrid MiniMAX
  Reply With Quote
Old 15th October 2018, 02:10 PM   #695
Mark Johnson is offline Mark Johnson  United States
diyAudio Member
 
Mark Johnson's Avatar
 
Join Date: May 2011
Location: Silicon Valley
The diyAudio First Watt M2x
Default VERTICAL MOUNTING BRACKET FOR TOROIDAL TRANSFORMERS

Thank you, WKCox! Here are the sales pages for those mounting brackets:
L-Bracket from Toroid Corp

Omega-Bracket from Toroid Corp
  Reply With Quote
Old 15th October 2018, 03:25 PM   #696
JSA1971 is offline JSA1971  Canada
diyAudio Member
 
Join Date: Jan 2016
Location: North Toronto
The diyAudio First Watt M2x
Quote:
Originally Posted by WKCox View Post
Bracket is an L-300 from Toroid Corporation. The L-300 is a good fit for the AnTek AS-3218. I have also used the L-625 L-bracket which is a good fit for the Antek AS-4218.
Thanks WKCox! Iíve sent them an email for pricing.

Joe
  Reply With Quote
Old 15th October 2018, 03:29 PM   #697
JSA1971 is offline JSA1971  Canada
diyAudio Member
 
Join Date: Jan 2016
Location: North Toronto
The diyAudio First Watt M2x
Quote:
Originally Posted by Mark Johnson View Post
Thank you, WKCox! Here are the sales pages for those mounting brackets:
L-Bracket from Toroid Corp

Omega-Bracket from Toroid Corp
Thanks for the links Mark! I hadnít considered or even noticed the Omega bracket. I may consider that one instead.

Joe
  Reply With Quote
Old 15th October 2018, 03:30 PM   #698
MEPER is online now MEPER  Denmark
diyAudio Member
 
Join Date: Nov 2017
Location: Copenhagen
Quote:
Originally Posted by WKCox View Post
I don't think that there is any "cheap" Mu-Metal. I paid $122 for a 2' x 4" x 0.01" piece of Mu-Metal foil from McMaster Carr.

Before the Mu-Metal shielding, I was seeing noise levels of around the 500 uV, which is the First Watt specification for the production version. After shielding, I measure around 100 uV (0.1 mV), which is quite an improvement and the limit of my test equipment.

I'm sure there will be more feedback for builders regarding shielding techniques as more people build the M2x.


I have become a fan of having the PSU in a separate chassis. This will be my approach when building the M2X.....or any amp.
  Reply With Quote
Old 22nd October 2018, 04:48 PM   #699
dBel84 is offline dBel84  United States
diyAudio Member
 
Join Date: Jul 2006
My first foray into Pappa's world. ( as long as you don't count modifying old ADCOM mosfet amps )

A good story always starts at the begining, which in my case started with a pair of HK775's which I bought to tinker with and was curious how they sounded.

HK775
Click the image to open in full size.

After replacing one of the push buttons and trying to clean up the amp, I ended up giving them a face lift
= much to some purists distress.

Click the image to open in full size.

I have been lurking on the Pass forum for a very long time, most of my DIY endeavors have been headphone oriented, so little need to spend much thought aside from curiosity. Then while working late one night I happened to stumble on an add for a set of M2x boards - I had been toying with buying the First Watt M2 and just never pulled the trigger and had let the original GB pass me by as I had too many other things going on at the time, so this was a momentary lapse of reason and a little late night weakness/delirium

Click the image to open in full size.

This weakness had mostly been spurred on by ZenMod's fantastical thread "Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans"

I then enquired from the person that I bought the M2X from as to what had driven him to unload this precious cargo and the next thing I knew ....

Click the image to open in full size.

tested them to make sure they were good

Click the image to open in full size.

but that remains for another day.

I guess I have become a little derailed in my story telling as not soon after had I refurbished the HK's and had them singing some fairly impressive tunes, one died with the release of special faerie dust never to be rescussitated . Now that I had a set of boards, I got to thinking , would they fit ? The heatsinks are thick solid blocks of aluminum so I gutted the original carcass and voila, a near perfect fit.

Click the image to open in full size.

As the chassis is mono, I did some patching and modified it to stereo

Click the image to open in full size.

I by this time had gradually paged through all of the M2 and M2x threads and became aware of a theme that was a little concerning - noise in the signal , most likely being picked up by the edcor transformer that the M2 uses. Hum has been a point of sore contention recently as I have spent most every free minute trying to kill an annoying hum that has plagued a tube hybrid headphone amp I had built.

I recalled that a dear friend of mine had designed a current limiter and noise cleaner for a pair of smps supplies I had.

Click the image to open in full size.

I tested it bolted to external heatsinks and it worked perfectly. I needed to reseat the mosfets under the board as the rig with the heatsinks didn't fit in the case - got it looking good with a nice tight fit and tested again - nothing, for some reason the Fets would not switch on - they test well out of the board but something else must have happened and I was getting inpatient with it all - probably a good time to stop and take a breather but instead I rigged up a little CRC and wired it up for testing.

Click the image to open in full size.

I built 3 of the little input boards - turns out I didn't have suitable NPN transistors for mountain view, so waiting on another mouser order and I thought I had the correct brass nuts to seat the input board but alas - nothing in my parts bin would fit. Probably a good thing as this will afford me time to go over the build once more before I power it up.

Still a lot to do for the final amp but almost at a point ready to test.

..dB
  Reply With Quote
Old 22nd October 2018, 06:43 PM   #700
Mark Johnson is offline Mark Johnson  United States
diyAudio Member
 
Mark Johnson's Avatar
 
Join Date: May 2011
Location: Silicon Valley
The diyAudio First Watt M2x
The class A quiescent power dissipation of an M2x is somewhere in the neighborhood of 70 watts per channel*. Multiply that by the thermal resistance of your salvaged HK heatsinks to estimate their temperature rise above ambient air temperature.

*The FirstWatt M2 manual says 160 watts total, which includes a bit of dissipation in the power transformer and the inrush current limiter discs and the bridge rectifiers and the CRC filters.
  Reply With Quote

Reply


The diyAudio First Watt M2xHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
What make and model are the original drivers in Wilson Watt&Puppy 7 (WATT) aguiarrj Multi-Way 17 24th June 2017 11:39 PM
2.3 watt x 4 or 5 watt x2 SET amplifier using DECWARE Zkit1 and Zkit4 schematics Redwolf92 Tubes / Valves 12 29th October 2014 11:19 PM
diyaudio moderator vs diyaudio member Leolabs Everything Else 6 18th June 2006 09:19 AM


New To Site? Need Help?

All times are GMT. The time now is 01:40 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki