Mini review: Class-D Designs NX200 vs Hypex - Page 13 - diyAudio
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Old 18th May 2009, 04:22 PM   #121
jkeny is offline jkeny  Ireland
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Spitzer,
I fully agree with glt - your posts we get chop though you seem unlike go to understandble for without!
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Old 18th May 2009, 04:22 PM   #122
AndrewT is offline AndrewT  Scotland
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Hi Spitzer,
is there a message in there?
I can't find it.
__________________
regards Andrew T.
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Old 20th May 2009, 10:55 PM   #123
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Made a few changes:

Replaced on board PSU caps with 100uF 100V Rubycon ZLH
Bypassed 22uF ceramic coupling cap
Replaced 47uF electrolytic feedback cap with 4x22uF fostex branded film caps
Drilled lots of ventilation holes in the base and sides of the case (it was sealed before)

Changes? Now you can see the modules yellow and blue LEDs glowing through the holes in the case. Sounds a bit different too :-)

Possibly a touch leaner but upper mid and HF clarity far improved. Generally sounds a bit cleaner and more sophisticated, if that makes any sense.

Probably be fire burned at the crossed wood by a certain ******* - oh well.
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Old 20th May 2009, 10:58 PM   #124
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Insides after mods:
Attached Images
File Type: jpg pimped small.jpg (84.2 KB, 432 views)
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Old 20th May 2009, 10:59 PM   #125
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Glowing modules:
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File Type: jpg glowig small.jpg (70.7 KB, 411 views)
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Old 21st May 2009, 02:45 AM   #126
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Very nice build Sharpi31 - looks great.
Except - you're going to need some heat sinks on that case. They're not class-d you know

I think Spitzer puts it best when he says:
"this now daily cook"
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Old 21st May 2009, 02:57 PM   #127
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Old 21st May 2009, 03:07 PM   #128
jkeny is offline jkeny  Ireland
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Sharpie,
Good build! Those yellow caps are the Fostex 22uF caps, I take it! That's a fairly major mod. Did you do bypass the ceramic input caps first & then listen or dive straight in with both mods i.e is the bypass responsible for the extra clarity at HF? What does the feedback mod do for the sound?

Iain, good moderation work! Thanks
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Old 21st May 2009, 11:02 PM   #129
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I bypassed the coupling caps first - this cleaned up the HF and seemed to remove a degree of harshness (not that the amp was noticeably harsh beforehand).

Next I replaced the PSU and feedback caps (the big yellow caps replace the electrolytic feedback cap on the board). This increased smoothness while opening up the mids a bit.

To be honest the amp sounded good from the start. The mods improved the performance - more than subtley but not dramatically. Definitely worthwhile though.

I'm waiting for some of the new 22uF Wima MKS 2-XL caps to arrive. These are really small low voltage film caps that would have been far easier to fit in place of the electrolytic feedback cap. I used the big Fostex caps but may still change to the Wimas when they arrive. The Wimas would allow for much shorter connections which can only be a good thing.
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Old 21st May 2009, 11:26 PM   #130
jkeny is offline jkeny  Ireland
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Thanks for the report of the stages - it is even more informative & maybe Mike is listening in & could respond.

I came across these caps recently which seem to be stellar performers based on their specs & could have a role here http://www.paktron.com/pdf/Angstor_RA.pdf

They are Ultra-Low ESR Multilayer metallised polymer film capacitors. Capacitance values range from 0.1 F to 20 F and the voltage ratings are 50 VDC to 500 VDC.

This UK co is a distributor http://www.futureelectronics.com/en/...ges/index.aspx
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