Hypex NC400 mods and assembly

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Ric Schultz

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Hypex NC400 mods and assembly
« on: 19 Oct 2012, 11:58 pm »
We can assemble completed NC400 amps for you and also modify your assembled amps with our latest updates. 

The most important things to get better sound in a NC400 build are:
1. Use an audiophile fuse....makes a big difference, much more full, and lower distortion....we sell the Furutech fuses.
2. Bypass the binding posts using my binding post bypass system.  Depending on the connector you use can vary from better to way better.
3. Bypass the output connectors on the NC400 board.  Makes the amps much more full and palpable.  We remove the stock connectors and replace them with PCOCC 16 gauge wire that you solder the output wire to.
4. Change all of the Polyester .68uf output filter caps to pairs of modded .33 uf Polyprop caps.  Lowers noise way down....Way more transparent.  Its as if you scrubbed the noise away and it is sooooooooo much more palpable and real......amazing amount of space/reverb/air now.  The Polyprop caps have the stock leads removed and replaced with 6N copper leads and the caps are marked for outside foil polarity.  The caps are mounted so the outside foil is oriented to ground. 
5. Use good IEC and input connectors.
6. Use good wire on the output (soldered to the new bypass connectors on the NC400 and run outside the amp and wrapped around the binding posts).
7. Add an AudioMagic Pulse Gen ZX to the input power (two if dual mono).
8. Exotic feet and damping
9. Balanced configuration.  More air, more detail, more dynamic and more vivid

You do all the above and you have one super transparent amplifier. 

Mods done to the modules (cap and output connector mod) will void the Hypex warrantee.  However, the modded modues are not any less reliable than the stock modules......which are extremely reliable.

Pic of the NC400 output connector mod and the cap mod:

Pricing will depend on what kind of build/mod you want and what level of parts you want to use.  We can source the chassis and parts or you can send me the chassis and parts.  I charge $75 an hour for my labor. 

For instance, say you already have an assembled amp but want our serious updates.  We can do the connector mod and cap mod on your NC400 modules and drill holes in your chassis to run the wires outside and wrap around the binding posts for $300 ($100 for the 12 modded caps, $100 to install them and $100 to install the PCOCC jumpers, drill holes in the chassis, install grommets and install the output wire).  Another $96 gets you Furutech fuses.

Assembly of a set of monos or a dual mono can be anywhere from 2-5 hours ($150-$375).

An example of an (all out) full assembly including parts cost:
2 mono chassis  $175-$200?
Two Furutech FI-10 Gold IEC connectors $55
Two Furutech Gold FT-786F XLR input connectors $84
Dayton Binding posts (acting as clamps only) $35
14 gauge PCOCC litz Output wires $20
2 Furutech fuses $96
12 modified .33 Wima caps $100
install OCOCC output wire connectors, and run output wire through a grommet and wrap around the outside of the binding post
5 hours labor $375
Total $950 or so.....this does not include you sending me your modules and power supplies or return shipping.

Example of simple assembly:
Chassis $175-200
2 Schurter IECs $3
2 Neutrik XLRs $12
2 sets Dayton posts $35
Wire $2
Labor $250 including running wires to outside of amp and wrapping around binding posts
Total $475 plus

We can do whatever you like.  From simple to way out.  The pricing above assumes the chassis are already punched or mostly punched for all the parts.  If the chassis needs mucho drilling and work then the labor price goes up.

If you just want the 12 modified caps (6 pairs) for your own installation then it is $100.

Call for details.  831-338-2896 Pacific time.

« Last Edit: 5 Nov 2013, 08:10 pm by Ric Schultz »


Re: Hypex NC400 mods and assembly
« Reply #1 on: 20 Oct 2012, 12:03 am »
Very important to mention that these mods are not Hypex approved and will void your warranty. 

Do you (Ric) offer a warranty on the modules once modded?

Ric Schultz

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Re: Hypex NC400 mods and assembly
« Reply #2 on: 20 Oct 2012, 12:30 am »
Thanks for reminding me, I was going to mention that.  For sure, the mods to the module (cap and output connector mod).....not anything else, will void the manufactures warrantee of the module.  No, I don't offer any warrantee on the modded modules.  They are not any less reliable than the stock modules.  How many stock modules have failed in normal use?  Anyone?

Ric Schultz

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Re: Hypex NC400 mods and assembly
« Reply #3 on: 20 Oct 2012, 10:50 pm »
More on the Wima cap mod:

I started using the tiny Wimas when I discovered years ago they sounded about as good as a V-cap Teflon on the input of the modified Nuforce amps I was selling.  After a couple of years Wima changed the copper leads to steel (worse sound) so I decided to dremel off the steel leads and use 6N copper leads instead.  At the same time I started marking the caps for polarity (because they were so small I was not sure you could figure out the outside foil or that it would make a difference...but I was wrong).  The combo of making naked the sides, adding better wire and orienting the caps correctly made for one seriously fast transparent capacitor.  The Wima poly props only go up to .33uf but they are better sounding then the Wima Polyester caps.  When I would need a large value coupling cap I would use a 2uf modified polyester bypassed by a .1 or .33 modified Polyprop.   

So, when I saw the stock .68 Polyester Wimas in the NC400 I naturally got excited that I could make a quite noticeable difference here.  I first removed one of the .68uf Polyesters and measured the amp.  It measured slightly more carrier frequency noise and slightly wider bandwidth.  However, listening this way was no good.  Very strident.  So, I modded the .68 I had removed and put it in and got somewhat better sound.  One of the .68s that I removed had steel leads and the other had copper leads.  Both caps had been put in with the outside foil to hot (not good).  I thought about just adding a .1uf modified polyprop but got the idea of subbing a pair of .33 polyprops for one .68 polyester.  Good move Ric!  Sound went through the roof.  Way more ambience, clarity and reality! 

By the way, I now measure a .8 volts peak to peak sign wave carrier but with the stock cap measured 1 volt peak to peak.  I could be wrong so I will do this measurement again when I mod the next amp.  If this is so then just having one of the three caps in the proper direction lowers the noise.  Remember, these caps are right next to the output coil.....so having the outside foil to ground is essential.  If Hypex would put all three caps in the correct directlon then the stock module would be better!

I can sell you two sets of modified and foil orientation marked Wimas for $40.  Very easy to remove the .68 on the end.....just grab with small pliers and rock front to back.....they break right off.  However, soldering them back on is tricky and easier if you already have done the output connector mod.

I had noticed the pic of the NC1200 on the Hypex website shows 6 output filter caps (no doubt the .33 polyprops), but later I saw a few pics of the NC1200 that showed just 3 caps (no doubt the .68 polyester).....so was wondering what they are actually shipping.  Well, last night saw the sneak peak preview on 6 moons of the Atsah amps and low an behold a pic of the insides showing 6 caps.  So, besides the beefier power supply, and one other N-Core technology the NC400 does not have, the NC1200 appears to be using polyprop caps instead of polyester.  Good move.  The only way you can use all polyprops in the NC400 is to stack them like I am doing.  So, no wonder the NC1200 sounds better (of course, there might be other reasons it sounds better).  However, the NC1200 products are using binding posts (not clamps).....so advantage in making your own NC400.  And with the NC400 at least some of the filter caps can be made even more linear and installed correctly than a stock NC1200.  Would be interesting to hear a stock Atsah versus a full EVS implementation of the NC400.  And if bridging makes a noticeable improvement then bridged modified NC400s might beat the Atsah or other stock NC1200 amps, for less than half the money ($3500-$4000 for bridged modded NC400s). 

Balanced operation of the amps:
Just plain better.  You get more ambience, lower noise floor, more vivid sound and transparency.  I think that bridging would do even more.....we shall see.

Below is pic of amp with speaker wires soldered directly to the new output connectors.  The other end of the speaker wire is soldered directly to his speaker drivers (15 inch woofers in two way biamped system).  Note the Furutech input connector with extremely short input wires (latest wires from NCore).

Pic shows an earlier modded unit with just one pair of the Wima caps changed....we now change all the caps

« Last Edit: 20 Nov 2013, 02:26 am by Ric Schultz »


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Re: Hypex NC400 mods and assembly
« Reply #4 on: 30 Oct 2012, 12:00 am »
Ric, cool mods…  It is too bad that Hypex did not consider some better caps for the output filter, especially considering the premium nature of the nC400.  At these frequencies, I would expect a polystyrene cap might be best…  but a custom unit would probably have to be made to get the 2uF value they seem to be looking for.  I guess next best would be metallicized polypro as you are using, and is able to be made in a small package.
If one is not doing the cap mod, it appears that removing the screw and nut from speaker tabs would allow one to solder speaker wiring directly to the remaining piece, which my investigation reveals must be either brass or copper (non magnetic).  This would probably be a good mod, and much easier than cutting off the existing piece.
BTW, close inspection of the nC1200 modules appears to show PET style output filter caps on that module as well...


Re: Hypex NC400 mods and assembly
« Reply #5 on: 30 Oct 2012, 12:02 am »
It is too bad that Hypex did not consider some better caps for the output filter,
Bruno has addressed why he didn't in the diy thread.  Bottom line, not needed. 


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Re: Hypex NC400 mods and assembly
« Reply #6 on: 30 Oct 2012, 12:15 am »
jt, yeah, I kind of remember reading that… but that thread is so long now, and DIYa's search engine is rarely good enough to find what one is looking for!
In any case, I am sure BP is correct in saying it is not "needed", but it still may change the sound for the better.  It is difficult to find out though, as doing mods to these boards is problematic in trying to evaluate the results, unless one has an AP2 handy.  Still, anyone with experience evaluating different capacitors used in parallel filter circuits like this might expect to hear differences… despite the filter being within the feedback loop.  I certainly would not mess with the OE caps myself, I would be too worried about adding antennas which I could not objectively evaluate: ie, is the mod making it sound better (more transparent to the source), or s the mod just allowing more RF hash into the output.