I have heard that before, that TOO much ERS can dull the sound...
Best,
Anand.
OK, OK.... I've been getting a bunch of emails and PMs so let me address what I did and why in building Roger's amp.
First, the ERS cloth. ERS is the weirdest material that I have ever worked with and defies explanation and goes beyond logic in some ways. Why does a material that works solely in the RF region sometimes have an obvious effect and sometimes not? That is a hard one - suffice to say that it just does. Is it ever a profound effect? Nope, at least not to my ears. Remember that I am a hard core subjectivist when it comes to audio... a recovering hard core objectivist. There are some things that I have just quit trying to wrap my inquisitive head around and recognize that they "may" or "may not" have a beneficial effect in a particular application. It is an instance of what our Aussie friends call "suck it and see" or as we say, "give it a try." ERS was used in my first BUSSes, but not in the recent ones. Why? Because I changed some materials in the newer ones that eliminated the need for ERS.
So, why does ERS work in this application? Because it does, that's why. I tried it with and without in several different configurations and ended up with about half of what is seen in the picture. It is located only over the SMPS. Like I said, the soundstage was better with the ERS than without and better as I reduced the size to what it is now. ERS is like gravity: it works and part of it can be measured and quantified, but in the final analysis, we still don't fully understand it. ERS is NOT like gravity in the context of constant functionality. Gravity is pretty much a given.
This brings us to the real topic of my missive here and in my business as well as my life. I loathe and detest noise. From the noise on the street or in a restaurant, to the RFI that plays hell with good audio reproduction, noise sucks. In audio, noise sucks power from amplifiers, clarity in all kinds of circuits and life out of the music. To prove a point many years ago I bought two of the same portable boom boxes. In one of them I went on a noise hunt. Took months. From the power supplies to resistors, to cabinet damping I searched for everything that was a noise contributor. In the end, there was no sonic comparison. The boom box became a reasonable source for music. I still use that sucker in my garage. Sounds awful now due to age, dust and abuse, but it serves to remind me of why I do what I do.
On to Roger's amp. When Roger asked me to build him an Ncore amp, I was really blessed by him asking. He and I have become good friends over the past few years, even though we have never met face to face. We have a great deal in common. I decided that I would build him an amp in the way I would build it for me, not just do an assembly job. That meant that I would employ every technique that I know to eliminate the SMPS noise form the amp (within reason). I'm a wood butcher. I don't have access to machine tools or the talents of Matt Kramer or Jason to do what they do, I had to go with what I know. That is: noise reduction; layout; cryo and common sense.
Cryo - cryo is like a good chiropractor. it removes tension and stress in the materials. There are also changes to the materials on a molecular and crystalline lattice/boundary level that are well documented and don't need explanation here. Cryo works. Accept the fact... it just does. I cryoed the guts of the amp. Everything I put in my products is cryoed. It's like chicken soup - couldn't hurt. I'm a CryoGuy to the max.
Noise reduction: I approached this from two directions - compartmentalization and shielding. The mu metal and copper foil shield was used to provide as much ground plane shielding as possible. I wired this as a Class 2 device with the earth (ground) unattached to the chassis. All of the shielding is attached to earth. Having everything grounded to a common point with a SMPS is a great way to make a tiny radio station out of the ground plane. YMMV. I'm just sayin'. Try running down a problem in the D-ground in a recording console sometime..........
Having established the two compartments, I twisted the cabling and used copper foil to shield the wiring. I twisted the wiring for the two SMPS in opposite directions because it just makes sense to do so and takes no additional time. Mutual induction is probably not an issue with this layout, but why not just do it? I kept everything that had to do with power in the power compartment as much as possible.
On the amplifier side of things, I simply kept everything as short as possible and added a bit of additional shielding here and there.
NOTE: I really, really don't like the signal cable used in the Ncore kit. In the future I would change that wiring out to something more substantial and user/builder/sonically friendly.
NOTE: the guy that thought that super bright blue LEDs would be a good idea should be... (insert your option here) I eventually ended up installing a back lit switch on the front panel for Roger.
On the power inlet side, I went with a Furutech gold plated power inlet because I like them and they "sound good" - yeah, I know... better than the power inlet used in the plans.
I'm not a scientist, just an audio guy. I build the way I build because I have found it to be the best sounding way to do things over many years of experience.
Again, YMMV.
Dave
