[jtwrace]

If you're interested in getting it measured and having the results posted I could probably make this happen for you. 

[revelinhifi]

We don't really know if this is an improvement. All we know is that you prefer it. It is completely subjective.

absolutely true however I know the results myself and wanted to share and if another person tries they will know the same and may want to share.

It is easy to revert back to the stock caps if I felt the change was negative, if you follow good procedures to replace the caps it is only time and skill which I had available. Minimum heat time to the PCB is essential

here is some of my process to remove caps and verify yourself if interested.

If the pneumatic solder sucker did not get all the solder out in one session for each cap I would wriggle the capacitor while putting heat on one leg at a time to remove the cap. my success rate with the pneumatic solder sucker two out of three caps, the remaining required some manual intervention.

Then to clean the hole I would get my 9 year old son to help, here I will explain that process = I would have my son hold and have ready the manual solder sucker pump on the upside of the board while I held the NC400 and applied heat to the lower side hole. this method cleaned the hole beautifully and quickly, very little heat time on the board.
 
Thanks
John
 

[revelinhifi]

Thanks JT for the offer

I am in New Zealand, and this is not very economical to take that action, also my listening enjoyment would be gone.

Its not that important to me the measurements though it interest me some. In the near future I could take my amp to a technician who could do the measurements and report back the results, - see if there is any deviation from stock.

A cannot promise a quick turn around on that, the driving passion to do that is not really there, only a small amount of interest in doing that, I'm thinking it will be very close or same to stock. And that is the small amount of interest which may drive me to verify this fact.

Thanks
John
 

[Julf]

The un-modified unit was compared to the modified unit before completing all four. All I had to do was swap speakers between the amps.

But you did the swapping yourself, so you knew which was which?

No I have not asked Bruno; to ask that question you would want to be supported by measurements of the modified amp.

I'm just curious if his reaction would have been "Ah yes, good idea, we did cut some corners there!" or "That is a really bad idea, because...".

[jtwrace]

I am in New Zealand, and this is not very economical to take that action, also my listening enjoyment would be gone.

Understood.  If anyone in the USA has done the same I'll extend it to you. 

[revelinhifi]

But you did the swapping yourself, so you knew which was which?

I've done many changes over the years and had many components. you know when you get a better sounding product right?
I went from a MK1 PS Audio DAC to a MK11 the SQ was a good upgrade this change to the NC400 is easily as good a contribution to better SQ

I'm just curious if his reaction would have been "Ah yes, good idea, we did cut some corners there!" or "That is a really bad idea, because...".

Feel free to ask Bruno as I was saying there are manufacturing difficulties with implementing the polypropylene cap there is not enough space to accommodate 6 caps as a DIY there is the benefit of doing something non standard, it may measure the same perhaps but sound different to the EAR Hmm

[revelinhifi]

Understood.  If anyone in the USA has done the same I'll extend it to you.

I am hopeful someone may like to mod there NC400 and benefit from improved SQ 

[Julf]

it may measure the same perhaps but sound different to the EAR Hmm

So what is your view - why would it sound different if there are no measurable differences?

[revelinhifi]

So what is your view - why would it sound different if there are no measurable differences?

Have you ever swapped out a standard fuse? one which was not reputed to be audiophile grade! I have, and there was an audible SQ improvement.

My back ground was in a technical field and I doubted the benefits of such a change as it did not add up for me, till one day I said to myself what is there to loose $100.00 as people were reporting through numerous accounts of the SQ improvement, I did this in my PS Audio DAC and heard the SQ improvement.

My view is different material can sound different and only our EAR is able to detect an audible change and the change is not measurable with the level of technology available today. i.e. Science needs to invent a new measuring tool - perhaps there is a measurement not yet known that can justify why there is a difference in sound. Our physics and science has not worked this yet to be discovered measurement out yet.  Hmm I especially enjoyed the America's cup "yachting' recently and the implementation and use of equipment enabling a significantly faster upwind than actual wind speed only recently this was achieved. The same elements have been there for how long. Now what is needed is some serious investment for a new tool that can match the Human EAR and measure why a material can sound different over another, though the measure the same with our limited understanding of physics we know today. There are laws not yet quantified.

I am thankful to some who try new things, that on the face of it should not make an audible SQ difference. So if it seems plausible and has some sense with the understanding I have and it lacks known science I'm a chap who is willing to give it a go - and let my EAR tell me if the SQ has improved. When it comes to this my passion for the hobby I love. I understand that all people are not the same in this respect and have doubts and are less willing to give things a try. I am an amateur radio operator and reasonably skilled at making these types of changes at the circuit board level. It is easy to go back though I have stated this won't be happening as the SQ is significantly improved over the stock unit with capacitor change. Last night I could describe the listening session as having a set of headphones on my head and in my own private world. I was listening at a reasonably low level due to the lateness and the ability for the NC400 to amplify as it don't was awesome it was never this good. The soundstage is so focused and clear and very musical.

So to sum up we don't have instruments available to day which can measure the difference we can hear with our ear yet we cannot make measurements to explain the difference in what we hear with our ear. There is lacking in a tool and a measurement, please find this tool and measurement to explain what we hear with our ear. When measuring different elements which measure the same with the physics we know.

So what is your view - why would it sound different if there are no measurable differences!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! type written through dragon dictating
 
 Thanks John

[barrows]

Differences in sonic characteristics of polyester vs polypropylene capacitors of the same value are well documented: do you believe in using polyester caps for loudspeaker crossovers?  Also, these capacitors will measure differently, polypropylene is a lower loss dielectric.  Every cap is going to absorb some signal, and then release that energy as a time delayed signal, the less signal loss is, the less time smear will be audible.  If we had a "perfect" cap, none of this would matter, but components are never perfect.  The closer to perfect the cap becomes, the closer to transparent the filter circuit is.

What I do not understand is the reference to outer foil?  Wimas are stacked caps, they are not wound right?  So how is there an outer foil?

As to whether Hypex could use something "better" than the Wima polyester caps, that would probably require having a custom cap built, which would be possible, but raise prices.
I have noted before that Mola Mola states clearly that their amplifiers use, what sounds like, a custom "monolithic" capacitor for the output filter (as opposed to the film caps on the OEM NC-1200 modules).  So, it appears that Bruno does accept that their are different sonic signatures for different capacitor types.  To me, "monolithic" typically indicates a ceramic cap, which is odd, as most audio folks feel ceramic caps do not fair well for filtering analog signal paths, any ideas on what os going on with the Mola Mola amps?

Revel: thanks for great pictures of your mods!

[revelinhifi]

Thanks Barrows 

I was interested to provoke thought the fact is the SQ is better with another CAP same value though different construction and material. I am listening to better SQ

apparently with an oscilloscope and a particular test the caps shows that there is an orientation and they are installed the same orientation in the NC400 also losing steel leads. Yes Hypex would need to find another cap if they wanted to change the tine of the current stock. Hypex went with the polyester and as a DIY, one can change those caps if they wish, having read other peoples results from having done it. if there was less conversation about this topic then less people would realise the potential and be able to enjoy more SQ from the NC400, I'm happy to make that known 

Cheers
John

[Julf]

So what is your view - why would it sound different if there are no measurable differences

I can't think of any reason, so that is why I asked. I am not saying there can't be differences, but I would have to see verified results of a double-blind ABX before I would start to look for new ways to measure hitherto unmeasurable differences.

[barrows]

I can't think of any reason, so that is why I asked. I am not saying there can't be differences, but I would have to see verified results of a double-blind ABX before I would start to look for new ways to measure hitherto unmeasurable differences.

Julf, I think there are big problems with measuring time smear.  My suspicion is that many different things in the signal add different amounts, and different durations of time smear, these are subtle (at best) and they add up to the overall final result.  The history of audio is full of of examples of things which are believed to cause sonic problems, which no one realizes how to measure, then, when a way to measure the problem is found, the result often confirms what the listeners were hearing all along.  A more recent example of this is ESS and their attempts to improve DS modulator design, their engineers accepted that there were problems not shown in the traditional measurement set (caused by inter transient noise in the modulator).  They found a way to measure the problem, and then went back to the listening tests.  Their listeners could detect when turned on and off the "solution" used in their "hyper stream" modulator design.  So, here we have a group of engineers using a listening test to improve their DAC design, and then confirming these results through a new measurement protocol.

[Julf]

Their listeners could detect when turned on and off the "solution" used in their "hyper stream" modulator design.

So it was a blind listening situation?

So, here we have a group of engineers using a listening test to improve their DAC design, and then confirming these results through a new measurement protocol.

Yes - and that is how engineering (and science in gereral) works. You make observations, you verify them, and based on that you develop more sophisticated models and measurement methods.

An essential part of that is *verifying* your observations. Among other things, it means ensuring the observations are not caused by other factors such as perception bias.

[revelinhifi]

You would have to have significant hearing loss at the higher audio frequencies not to be able to distinguish the stock unit from the modified NC400. The same goes for the midrange. I'm happy with the Bass as well there is good balance.

Ill say again as there has been lots said and it may have gotten lost - I had the NC400 for a year or more and I was very familiar with the sound signature. Also I was able to AB just by swapping the speaker leads overs. The input was not changed as the input was split feeding each amp pair.

The SQ improvement is not small like swapping a cable, now I said this was on par with going from a PS Audio Mk1 DAC board to a PS Audio MK11 DAC board, (search and read those reviews if you like) those who have done that will know the SQ difference I'm talking about. You don't need someone sitting next to you say did you hear that difference, because its that significant.

If you are an NC400 owner and you are wondering were the Highs and the Midrange is well its trapped - filtered in those polyester caps  the polypropylene caps lets that sound out for sure

I've said enough now and wont repeat myself anymore, and will comment only when I have something else that is worth sharing that genuinely improves the music experience heard.

Enjoy the music I am

John

 

[Julf]

So I guess that's a "no" then.

[revelinhifi]

Was not required, I am entirely confident in what I hear and know when SQ is improved.

NO other person was involved to give an AB comparison.

One thing I have not mentioned. The sound stage is more believable, improved focus on instruments. this is an interesting factor if something was less accurate there is a good chance imaging performance would suffer however this is improved over the stock NC400     

[Ric Schultz]

Wima caps are not stacked foil.  The pics on the spec sheets make it look like they have stacked construction....not so.  They are wound just like any other cap.  So, the outside foil is very measureable and sonically important.

The difference between polyester and polyprop is only one reason why these make the sound better.  The ends are ground off and the steel leads are changed to 6N copper leads and then they are marked for outside foil and all caps put in the correct direction.  The stock polyester caps have steel leads, more epoxy and plastic on the ends and are put in with no thought to outside foil orientation.  All these things are important for sound.

[farquad]

The problem with hearing is its not 100% what the ears are registering. The brain uses any relevant information to interpret what you are "hearing".
If what the eyes tells you is in conflict with what the ears are registering, the brain might go with what the eyes tell the brain it should be hearing.
Have you heard of the MCGurkeffect?
http://www.youtube.com/watch?v=G-lN8vWm3m0

So if you "want" your modification to sound better, there is a big chance it does sound better. To your brain. But that doesnt mean there is a difference to the sound.

[cab]

It could also be that it sounds "better" to you. That doesn't mean that the amp has been objectively improved, it means it sounds different.