[Antistase]

My second MMax is playing. Still breaking in but I tend to reckon I like it better enough than my old one. Of course I can't make a direct comparison as I used different resistors,  boutique caps caps and bjt in this one.
One of the first impressions is  that the 12FM6s play significantly better in this version. 
Also, strangely, with this board I don't get any hum touching the naked pot even without grounding it.
 
As usual I run then amp rather high at 30V, 19V tube bias and 130mv bjt bias.
 
I need to case it and then build a grub. I'm probably not paying attention but I couldn't find instructions to connect it to the MM 1.2 board. 
Also are drilling templates available for using the bottom slot of the standard case ( as I'm using 1" heat sinks) and with the USB hole? Not a big issue to work this out, as the pain is the top plate, but in case they are already available it would make the job quicker.
 
A
 
 
 
 

 

[jdkJake]

Looks great!

All of the templates are on the MOSFET-MAX site. Don't pay attention to the thumbnails, the downloads are correct. They have the USB location on the back panel. As for the bottom, I just repeated the top pattern. It lines up well with the vent holes in the board.

Did you build BJTs or MOSFETs?

jk

 

[Antistase]

I used BJT. I've never found a mosfet amplifier I like. My M3 included. And, as the MM uses more or less the same buffer as the M3 I decided to stick with BJT. I have to state that I'm a committed thermionic amp estimator and builder but  can't find any subjective ground backing the claim mosfets sound more like triodes than SS (because supposed 2nd harmonic distortion dominance).
 
This time I used the 2344/101 whilst my other MM uses 2238/968. I also, this time, splashed on prp and mills resistors.
Like Thomas says the 2234 gives amazing drumming. I will wait to see if the lower frequencies will get more body as I'm super spoiled with my old MM on K42Y+2239/968. I used tapped heat sink this time to make power BJTs replacement less painful.
 
This MM makes my Beyer DT48S Nagra, and my self too, extremely happy.
 
 
Cheers,
A
 
 
 

 

[Aalelan]

 
First time Amp builder here and I have started with the MOSFET MAX.  After some woes of following the Digikey BOM (didn't see that post soon enough ) The last of my parts should be here on July 7th.  I cant wait!!  Here is a shot of what I have got so far and a link to my gallery for the process..
 
http://www.aalelan.com/gallery3/index.php/Projects/Millett-Hybrid-MOSFET-MAX
 

 

[Aalelan]

 
First time Amp builder here and I have started with the MOSFET MAX.  After some woes of following the Digikey BOM (didn't see that post soon enough ) The last of my parts should be here on July 7th.  I cant wait!!  Here is a shot of what I have got so far and a link to my gallery for the process..
 
http://www.aalelan.com/gallery3/index.php/Projects/Millett-Hybrid-MOSFET-MAX
 

 

[Aalelan]

 
First time Amp builder here and I have started with the MOSFET MAX.  After some woes of following the Digikey BOM (didn't see that post soon enough ) The last of my parts should be here on July 7th.  I cant wait!!  Here is a shot of what I have got so far and a link to my gallery for the process..
 
http://www.aalelan.com/gallery3/index.php/Projects/Millett-Hybrid-MOSFET-MAX
 

 

[Aalelan]

First time Amp builder here and I have started with the MOSFET MAX.  After some woes of following the Digikey BOM (didn't see that post soon enough ) The last of my parts should be here on July 7th.  I cant wait!!  Here is a shot of what I have got so far and a link to my gallery for the process..
 
http://www.aalelan.com/gallery3/index.php/Projects/Millett-Hybrid-MOSFET-MAX
 

 
http://www.aalelan.com/gallery3/index.php/Projects/Millett-Hybrid-MOSFET-MAX
 
First time Amp builder here and I have started with the MOSFET MAX.  After some woes of following the Digikey BOM (didn't see that post soon enough ) The last of my parts should be here on July 7th.  I cant wait!!  Here is a shot of what I have got so far and a link to my gallery for the process..
 
http://www.aalelan.com/gallery3/index.php/Projects/Millett-Hybrid-MOSFET-MAX
 
First time Amp builder here and I have started with the MOSFET MAX.  After some woes of following the Digikey BOM (didn't see that post soon enough ) The last of my parts should be here on July 7th.  I cant wait!!  Here is a shot of what I have got so far and a link to my gallery for the process..
 
http://www.aalelan.com/gallery3/index.php/Projects/Millett-Hybrid-MOSFET-MAX

 

[jdkJake]

Looks like you are making good progress. One question, are you sure you want to jumper R1? What voltage do you intend to run at? I know it is marked as "optional" on the BOM, but, IMHO, it is not. You can always pick up a 10ohm, 1 watt from Rat Shack.

See: http://www.diyforums.org/MOSFET-MAX/MOSFET-MAXheaterResistor.php

You also might want to have a couple of resisters ready for RB14 as well. I know they are in the output path, but, you might need them to clean up the signal a bit.

Good luck and the remaining build!

jk

 

[jdkJake]

"This time I used the 2344/101 whilst my other MM uses 2238/968. I also, this time, splashed on prp and mills resistors."




Sounds very interesting. You will have to tell me what you think of the new combo after it gets a few hours on it. I still have a curiosity to build one with the 2238/968 combo, but, they seem to be made of "unobtainium". My mini has the 2234/101 combo, so, nothing probably gained by a max version of that build.



jk

 

[Aalelan]

I have a 10Ohm 1/2 watt that I can put in, I just jumped it out to start with, oh and I plan to just run at 27v..   I dont have anything for RB14 but that should not be hard to pick up..   There is an actual electronics store down the road, not a radio shack but real honest to goodness store.. Carries odd stuff and a little $$ but has saved me in a pinch a few times..

 

[jdkJake]

I have a 10Ohm 1/2 watt that I can put in, I just jumped it out to start with, oh and I plan to just run at 27v..   I dont have anything for RB14 but that should not be hard to pick up..   There is an actual electronics store down the road, not a radio shack but real honest to goodness store.. Carries odd stuff and a little $$ but has saved me in a pinch a few times..

You are a lucky fellow. All of ours have closed up.

I think you also need to check your JFET mounting. I think you have them in backwards. The artwork should not be followed for those parts.

See: http://www.diyforums.org/MOSFET-MAX/MOSFET-MAXmosfets.php

jk

 

[jdkJake]

I have a 10Ohm 1/2 watt that I can put in, I just jumped it out to start with, oh and I plan to just run at 27v..   I dont have anything for RB14 but that should not be hard to pick up..   There is an actual electronics store down the road, not a radio shack but real honest to goodness store.. Carries odd stuff and a little $$ but has saved me in a pinch a few times..

BTW, you should really consider installing R1 if you want to run at 27v. I would hate to see you damage your tubes over such a small part change.

jk

 

[jdkJake]

I have a 10Ohm 1/2 watt that I can put in, I just jumped it out to start with, oh and I plan to just run at 27v..   I dont have anything for RB14 but that should not be hard to pick up..   There is an actual electronics store down the road, not a radio shack but real honest to goodness store.. Carries odd stuff and a little $$ but has saved me in a pinch a few times..

One last item, since RB14 is in the signal path, a lot of folks use "boutique" parts. Just be careful not to just slap in any old resistor. It might hurt more than it helps.

jk

 

[tomb]

The RB14 resistors are required.  Unlike a BJT version, the MOSFETs will oscillate without them.  They won't overheat and blow up or anything - but it won't sound as good as it should - there will be ringing, etc. and harsh higher frequencies.
 
jdkjake is also correct - if those are JFETs at QB2 and QB3, they should be installed backwards relative to the silkscreen.

 

[jdkJake]

Quote:

Originally Posted by Aalelan /img/forum/go_quote.gif
 
Here is a shot of what I have got so far and a link to my gallery for the process..
 
http://www.aalelan.com/gallery3/index.php/Projects/Millett-Hybrid-MOSFET-MAX
 
 
 
http://www.aalelan.com/gallery3/index.php/Projects/Millett-Hybrid-MOSFET-MAX
 
First time Amp builder here and I have started with the MOSFET MAX.  After some woes of following the Digikey BOM (didn't see that post soon enough ) The last of my parts should be here on July 7th.  I cant wait!!  Here is a shot of what I have got so far and a link to my gallery for the process..
 
http://www.aalelan.com/gallery3/index.php/Projects/Millett-Hybrid-MOSFET-MAX
 
First time Amp builder here and I have started with the MOSFET MAX.  After some woes of following the Digikey BOM (didn't see that post soon enough ) The last of my parts should be here on July 7th.  I cant wait!!  Here is a shot of what I have got so far and a link to my gallery for the process..
 
http://www.aalelan.com/gallery3/index.php/Projects/Millett-Hybrid-MOSFET-MAX

 
Took a quick look at the build gallery. Did you re-order a new cap for CR4? The digikey part (tantalum) is incorrect, it needs to be an electrolytic. I made the same mistake initially. I think that cap can be as big as 100uf 35V and still work fine. Perhaps TomB can verify.
 
jk