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MDAC First Listen (part 00100110)

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moosemeat said:
I believe the PCB is only due to arrive today, hence the buzz is around VFET while John progresses the design of that... hopefully the arrival of the analog PCB will be the source of much excitement tomorrow!
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Ah, must have misunderstood that. Sorry! Wrong time grammar - "will arrive" instead of "have arrived".
But now it's true anyway.
Have fun with it, John! - more fun than me with my first amateurish soldering of the Ncores. I'll do it all again in a few days, then with better soldering station, more flexible cables and silver solder.
 
JohnW said:
Been playing with the VFET heatsink arrangement:-

Here are 4 variations....

https://dl.dropboxusercontent.com/u/86116171/VFET A02xxx.pdf

You can see from the top "look down" profile of the amplifier that the heatsink holes will be "rectangular" :)

The 4 variations are the sides of the heatsink (180mm High)
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Two more variations - my personal preference is the last variant or the 3rd from the left...

https://dl.dropboxusercontent.com/u/86116171/VFET A02xxxx.pdf

Any comments / suggestions?
 
JohnW said:
Been playing with the VFET heatsink arrangement:-

Here are 4 variations....

https://dl.dropboxusercontent.com/u/86116171/VFET A02xxx.pdf

You can see from the top "look down" profile of the amplifier that the heatsink holes will be "rectangular" :)

The 4 variations are the sides of the heatsink (180mm High)
Click to expand...

Looking better already imho. I've only ever used solid 'radiating' heatsinks so know nothing about the heat dissipation or the metal/air ratio of this kind of thing. The original (rows of 8 holes) looks more pleasing to my eye than one with rows of 10 or 11. Also, the number of holes in the top needs to match the number in each row at the sides: the lack of symmetry on the right hand 2 looks wrong. Finally, if a single row looked excellent on the original, and the new version is twice as high, then two rows (instead of three) should look OK on that, if it works from a thermal pov?

As there are at least 130 people more interested in that new pcb, I'll get my coat....
 
John what height will the output devices be at on the heatsink? I like the option with three equal holes, especially if you can mount the devices 2/3 down where the metal is, so to speak.

I built a phonostage with 300+ smt devices on it, never again.
 
sq225917 said:
John what height will the output devices be at on the heatsink? I like the option with three equal holes, especially if you can mount the devices 2/3 down where the metal is, so to speak.

I built a phonostage with 300+ smt devices on it, never again.
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Towards the bottom of the chassis to allow heat to travel up the heatsink....
 
davidjt said:
Looking better already imho. I've only ever used solid 'radiating' heatsinks so know nothing about the heat dissipation or the metal/air ratio of this kind of thing. The original (rows of 8 holes) looks more pleasing to my eye than one with rows of 10 or 11. /QUOTE]

The heatsink is now 400mm deep (as opposed to 330mm) so the top right view (with 10 holes / rows) is the original hole pitch but now 400mm deep (the pitch of the holes on the side of the heatsink would have to also match, but not shown).

The top left view (11 rows) is a slightly tighter pitch to increase the thermal dissipation.

Just playing with ideas....
Click to expand...
 
davidjt said:
if a single row looked excellent on the original, and the new version is twice as high, then two rows (instead of three) should look OK
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David,

I stacked the two heatsinks I have here (90mm each) so you have 2 slots & 180mm High, and it just didn't look right...

You have to factor how large these things really are - the heatsinks look far more chunky then it appear in the drawings - the 3mm chamfers around the holes help to highlight the "solidness".

I guess the root problem is the Height / depth ratio is wrong, the heatsinks are too high.... maybe reducing to 160mm will balance things out....
 
jirij said:
In my unimportant opinion, the right side seems like the way to go, especially the 3rd or 4th one from the right - good structural rigidness, good heat transfer ratio (considering the natural flow of room-temperature air) and simplicity - the left side just makes me dizzy from all the irregular holes. :)
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Yes I agree, if the Height / Depth ratio is corrected then RHS 3 (7) or 4 (8) might work even better :)
 
Thanks John, these are your amps though. I like your designs just fine.

My favorite is the one on the far left, but if you can not have any round holes and just try to get some rectangular angle thats my choice. Probably depends on the overall height of the unit.

cheers,
 
JohnW said:
VFET amp owners :)

I need to increase the height of the amp chassis to allow greater dissipation (cooler heatsinks) and to allow the height of the taller Plasma bargraph.

The original 90mm High heatsinks:-

https://dl.dropboxusercontent.com/u/86116171/VFET 100mm Heatsink.JPG

For the taller heatsinks, the CNC workshop just sent me this (ignore the front panel), I was trying to visualise the style of vent holes on the side of the milled heatsinks, so I request a few variations - at first I thought this "mix" was ugly, but now its started to grow on me AS IS! its certainly very unique and rather solid and expensive looking! :)

https://dl.dropboxusercontent.com/u/86116171/VFET tall Heatsink idea.jpg

The one change I would make is to have the "rectangular radiused" vent holes on the top (as per the original) rather then rounded holes of the taller versions...

What do you think? Take a few looks at the heatsink - see if it grows on you...

Otherwise we can choose a single style of hole pattern arrangement across the whole heatsink...

The more I work on this VFET amp project the more I excited I get :)
Click to expand...

Thanks for your advice ！ I have dowloaded all the upgrade exe . I can open the link by using VPN . I much admire your designed !
 
JohnW said:
Hi xiemeng,

I suggest A08 is the most stable software Beta, but V0.90 is the best sounding. V0.90 is more an engineering release as it lacks the features of the Beta.

If you have problems accessing the MDAC Wiki due to the Great firewall of China, then here is the direct Dropbox links.. Dominik whose located in China can access my Dropbox links, so I hope you can also.

V0.90:-

https://dl.dropboxusercontent.com/u/86116171/mdac v0.90.exe

A08:-

https://dl.dropboxusercontent.com/u/86116171/mdac-update_A.08.exe
Click to expand...

Besides , can you tell me what is the best setting of M-DAC ? I heard of different settings can result in a world of difference of sounds .
 
sq225917 said:
That pcb, shit the bed...
Click to expand...

Lol it's not a pretty colour in this picture, but I would be happy knowing the copper tracking is a good weight and even better if Captain Westlake could get away with non lead-free solder that cracks up after a few years :-D
 
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