[OzarkTom]

Measurements are a way of verifying/calibrating. What matters to me (if judging sound quality) is listening - but with my ears, not with my eyes or biases. What matters to you might be something entirely different.

Then start a new thread saying that and leave this one alone.

[Julf]

Then start a new thread saying that and leave this one alone.

The OP asked for responses to the idea of the capacitor modification. He did not state that evidence-based responses were excluded. If an open and balanced discussion bothers you, you should probably ignore this thread.

[audio-heaven]

This is an age old argument and I have yet to see any of them end well. Measurements are the most important thing 'up to a point', the Ncore's overall distortion is so low as to be inaudible to the human ear. The highest levels of distortion are always made by the speakers. I cannot agree with the view that nothing at all will effect's the performance of an amplifier. Or that science has an explanation for every phenomena that can be experienced by changing certain things in the audio chain. However I would always caution anyone against the 'modification' of a piece of electronics unless they know at least as much as the engineer that designed it.

The choice of a component by an engineer is not always determined by the necessity or desire to cut costs, there may be other very important reasons why they've carefully selected a part that we are unaware of.

It would seem that it's a part of human nature to 'always blame the new guy' when it comes to an apparent or perceived drop in performance. The countless times I've seen people say on audio forums - "I tried this new 'wonderamp' in my system and it sounded terrible, this thing has great reviews, really low distortion...... I just don't understand it"! The replies to this are usually "you tried it and you just didn't like it, send it back and try another" - and so it goes on. On the face of it that all sounds perfectly reasonable BUT not once have I ever seen anyone suggesting that the new amplifier is not poor at all, it's the rest of the system is not up to scratch. The new amp is only revealing the shortcomings that were previously masked by the lesser amp.

Why is that? After all that would explain the "good reviews" as well as the poor ones!

The point I am leading up to it that unless you are supremely confident that you have a 'well balanced' system and it is performing at the very best of it's ability it would be very unwise to tamper with the electronics. For starters you have no baseline to work from, all you will be doing is altering the sound and not necessarily for the better. Before judging an amplifier I would advise anyone to hear it coupled to the very best source and speakers you can possibly manage!

I own a pair of Ncore Monos and I've tried them out in quite a few different systems some better than others. Interestingly but rather unsurprisingly they always sounded great in the better systems.

Confession time: One thing I will say ~ and this bugs the hell out of me because it should not exist. I have always noticed a very real and dramatic improvement in SQ when some serious anti vibration control is used. Why this should effect solid state electronics I cannot begin to imagine, all I know is that it works but only if it's used throughout the entire system. I have tested it time and time again using double blind testing with different sets of ears. to date not one person has said they cannot hear a large improvement. Science has no explanation for this but my ears tell me otherwise.

[Toaster]

Good points well made. This is part of what I was alluding to earlier; a change that sounds better or worse in a particular system context with the expectations and preferences of particular listeners doesn't necessarily mean that the sound is qualitatively better- it may just be more complimentary to system and tastes. Like audio-heaven I have heard several pieces of equipment sound good and bad- or at least not as good- in different systems and rooms. Also, it isn't just some kind of crude polarisation or battle between 'subjective' and 'objective', there is a whole range of opinion on what can and does sound different, why this might be and what constitutes reasonable evidence. It is the absolute claims that some equipment (or tweek) is universally superior, without any qualification, that causes incredulity in some. On the other hand very 'hard' so-called 'objectivism' that pretty much denies anything except loudspeakers make a difference is also difficult to accept for anyone who listens before they buy or build. I can't see how Julf is that objective- he owns Isobariks! 

[Julf]

I can't see how Julf is that objective- he owns Isobariks! 

I never claim they are the peak of transparency or neutrality, or "better" in any absolute sense - I simply recognize that I like them, sonic warts and all. And when coupled with active filtering and EQ, and driven with high-current, high-damping-factor amps, they are actually somewhat better than their reputation (as long as you accept the tradeoffs of indirect sound).

[audio-heaven]

I never claim they are the peak of transparency or neutrality, or "better" in any absolute sense - I simply recognize that I like them, sonic warts and all. And when coupled with active filtering and EQ, and driven with high-current, high-damping-factor amps, they are actually somewhat better than their reputation (as long as you accept the tradeoffs of indirect sound).

I think you need to do a few tweaks to those Isobariks Julf  a few Teflon caps, a bit of platinum wire, solid kryptonite binding posts (to keep those pesky Supermen away).......... go on you know you want to 

[Julf]

I think you need to do a few tweaks to those Isobariks Julf  a few Teflon caps, a bit of platinum wire, solid kryptonite binding posts (to keep those pesky Supermen away).......... go on you know you want to 

Hmm... yes... And some chrome exhaust pipes and furry dice...

[audio-heaven]

Hmm... yes... And some chrome exhaust pipes and furry dice...

that's the spirit, I knew your resolve would crumble eventually. Just paint some flames up the sides, pop a chrome skull on top of em and then you'll have some really serious speakers 

[cab]

I would always caution anyone against the 'modification' of a piece of electronics unless they know at least as much as the engineer that designed it.

Good advice.

[Toaster]

I'd be interested to hear them Julf- I've only ever heard them 'back in the day' with contempory Naim stuff. Kind of like a cross between hi-fi and a good PA system. Diffuse stereo but solid and punchy. I'm veering completely OT though, sorry folks.

[Julf]

I'd be interested to hear them Julf- I've only ever heard them 'back in the day' with contempory Naim stuff. Kind of like a cross between hi-fi and a good PA system. Diffuse stereo but solid and punchy. I'm veering completely OT though, sorry folks.

Not wanting to continue much further OT either, but Isobariks definitely seem to be in the Marmite category. If you disable the top tweeter and mid, and compensate for the gain loss, they really change character - much more precise stereo, but those lovely room reflections are gone - it's  not a brik anymore! Some people complain about the "bextrene quack" of the B110 mid driver, but it doesn't seem to bother LS3/5A fans...

[barrows]

To revisit the idea of output filter capacitor mods to the NC-400 modules...  I was giving some thought to perhaps trying a previous poster's idea of using stacked PPS film caps, as these are small in size, and avaialble in .22 uF 100V, so a small stack of three would give .66 uF in each position, and keep the loop area very low.
First, I decided to do a little research, since there is not a lot of anecdotal sound quality reports for the PPS film caps.  I went in search of the technical specs (yes actual technical specs for you measurement types...) on various types of film caps.  So here are a few dielectric constants for various caps (for our purposes, lower is better). 

Air: 1, FEP (AKA Teflon): 2.1, Polypropylene (MKP): 2.2, Polyphenyl Sulfide (PPS): 3, and Polyester (PET, stock type): 3.2

So, the potential performance advantage of PPS over the stock PET caps is quite small (of course I would it would also eliminate the steel leads...), and the Polypropylene caps which Rick uses are considerably better.  I really wish Hypex had just had some custom sized polypropylene caps built for these modules... 

[Julf]

I would love to see a graph mapping dielectric constant to sound quality.

[jtwrace]

I really wish Hypex had just had some custom sized polypropylene caps built for these modules...

You should send Bruno an email about this. 

I would love to see a graph mapping dielectric constant to sound quality.

+1

[gstew]

I would love to see a graph mapping dielectric constant to sound quality.

See Jung & Marsh's 'Picking Capacitors' articles available here:

http://waltjung.org/Classic_Articles.html

In part 1, they list the various capacitors dielectric constants, then in part 2 they discuss the impact of dissipation factor & dielectric absorption on capacitor goodness & sound quality. As I read the articles, lower dielectric constant directly relates to lower dissipation factor and dielectric absorption and to better sound quality.

No direct graph, but pretty strong evidence.

Greg in Mississippi

[Julf]

As I read the articles, lower dielectric constant directly relates to lower dissipation factor and dielectric absorption and to better sound quality.

Lower dissipation factor and dielectric absorption, yes. The jump from that to audible effects is a leap of faith and speculation, and the articles you link to don't provide any evidence (or even rationale for) that leap of faith.

No direct graph, but pretty strong evidence.

Not really. Speculation. Not evidence.

[barrows]

Hmmm: lower dielectric constant sounds better.  Pretty simple really.  Dielectric constant tells the amount of loss of the signal into the dielectric (and subsequent delayed release, the memory effect).  This is the science, not speculation.
Now subjective evaluation of capacitors generally finds that capacitors with lower DA sound better.
So, we have actual technical specifications (measured) which show the DA of various types of caps, and we have a technical explanation of why higher DA would result in signal loss, and we have a correlation between these technical properties (measured) and subjective evaluations.
I am not seeing where there could be any doubt as to why and how different types of capacitors in the signal path can effect sound quality.  Perhaps the absolute level of the effect could be debated (and whether it is audible), but that there would be an effect is not. 

[Julf]

Hmmm: lower dielectric constant sounds better.

If you say so.

Dielectric constant tells the amount of loss of the signal into the dielectric (and subsequent delayed release, the memory effect).  This is the science, not speculation.

Science tells a higher dielectric constant means a higher amount of loss into the dielectric. Any extrapolations from that into audible effects is speculation.

So, we have actual technical specifications (measured) which show the DA of various types of caps, and we have a technical explanation of why higher DA would result in signal loss

In an attenuating circuit, the higher resistance of a resistor corresponds to higher loss. Does that imply that lower resistance values sound better per se?

[*Scotty*]

Julf, you could easily test the hypothesis that one cannot hear the difference between capacitors if you have access to a soldering iron and some film capacitors with differing dielectric construction. who knows what you might learn.
 The simplest test is to insert a series capacitor into the IC that is between your preamp and power amp. You can calculate the size required to give a subsonic rolloff characteristic to 1st. order filter that results when the capacitor is in-line. Theoretically you shouldn't be able to hear that a capacitor is even in the circuit if the pass-band is unaltered. Of course if you can hear the presence of the cap then it is possible that a capacitor with a low dielectric constant might be preferable in this application.
Scotty

[barrows]

If you say so.

Science tells a higher dielectric constant means a higher amount of loss into the dielectric. Any extrapolations from that into audible effects is speculation.

In an attenuating circuit, the higher resistance of a resistor corresponds to higher loss. Does that imply that lower resistance values sound better per se?

Actually, yes.  Ask any good analog circuit designer about this.  If it is possible to use less R, it is better, even just from a noise perspective.