The concern of Dennis Moorecroft was primarily electromagnetic fields that are self generated by the component itself. His component layout included not just minimizing parallel traces on PCB’s but also employed vertical connections to keep the desired orientation. As to RFI, I have no idea as to whether a metal box helps with blocking RFI or other external fields. I doubt that most chassis act like faraday cages.
The Accidental Tweak
Recently I turned my system on as usual and started listening to an album I know pretty much by heart. Halfway into it, a small voice in the back of my head started saying the system sounds really good today.
And it did sound fine. Maybe even... better than usual? No way I thought, I haven’t done anything to it. I must just be in a good mood.
It was not a life-changing improvement; just a bit more airiness, a tad more definition.
My Krell preamplifier made a world of difference when I introduced it to my system. I bought it in a still-working but near-death condition, and I started a regimen of fixing problems, listening for a couple of weeks, taking measurements, troubleshooting, fixing more stuff, all the while keeping tabs on bias and temps and DC offset.
The inside of this pre is gorgeous - all discrete, top-shelf components, not an IC in sight, the PCB laid out as if by a choreographer; it harks back to Krell’s long-gone heyday.
The cover was off during that process, ostensibly so I could check on stuff, but honestly I didn’t mind admiring the beautiful audio craftsmanship inside. Eventually its maladies were cured and I screwed the cover back on, I figured better before I spill a cup of coffee over the PCB.
Then it hit me: something did change, the cover went back on. Presumably that’s what I was hearing: it must have completed a Faraday cage around the pre’s sensitive single-ended circuitry, restoring shielding it probably needed because it sits inches from a pair of large, EMI-spewing monoblocks. The cover blocked the EMI / noise and that’s what I was hearing - or rather, not hearing.
But the true beauty in this is that I made this tweak completely unbeknownst of myself. In my mind I was putting a lid back on, not completing a Faraday cage, thus my brains never had a chance to develop the smallest expectation. To the opposite, I was trying to convince myself that I could not possibly be hearing anything (even though I was hearing something), because I had done nothing to my system.
So I know for sure that the sound improvement I heard, albeit subtle, was real, and that I believe is a rather unusual treat in this hobby.
Would love to hear similarly unintended improvements that happened to you guys.
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@tweak1 ”l replaced my…amp lid with a cutting board” I have a suggestion that may add some synergy to your amp tweak. Have you ever thought of trying the “cutting board” trick along with the latest reincarnated Leak “Sandwich” 250 speakers? Food for thought? |
I had exactly the opposite experience many years ago when running Perpetual Technologies dac setup. The Pt was a two box affair with very close fitting enclosure, I was doing incremental mods at the time so removing chassis from enclosure required. And so I listened with cover off and on, over time it became apparent sound quality superior with cover off, this regardless of mod performed. In researching cause of this I became aware that some enclosures can act as a capacitor through the phenomenon of parasitic capacitance. |
It is often a seemingly minor change that makes a huge difference either for the better or worse. I was at a shop where they swapped in a pair of speakers to try with a particular amp and the sound was surprisingly lack luster given what one normally hears with this amp. There was a pronounce lack of bass and overall energy. It turned out that the culprit was the amount of blue tak used between the speaker stand and the speaker. How could something like that make such a huge difference? That was the only change needed to make everything right. |
Some tube preamps will suffer noise if the cover is off. I changed out a tube , was listening to it and was wondering where the noise came from. Another tube, still noise. I pulled out my tester to make sure it wasn't a bad tube. Found out accidentally it was from the cover being off. Probably explains why the cover is so thick and heavy. |
