Could we all agree that one of the better design improvements to any electronic instrument is to use a EMI/RFI line filter, that is if it runs off line voltage. So much equipment do not have them = too cheap, but most of the good ones do since they have a bigger budgets or tighter constraints. The world is run off noisy supplies and too much RFI in the air, I think it is start to effect peoples minds.
Maybe a story to lighten up this RF conversation.
As a young tech, at Motorola, I was tasked with building a test fixture that used a couple of 2-way radios inside a Hammond steel box. I guess we could have used a couple of RF SG's but I guess they did not want to commit too instruments to this task, we had lots of radios in the factory to use.
The two transmitters, were set at different RF power levels (a few dBm diff) and set to tx at different freq. the test radio was connected to the attenuated combined RF signal. The test was see if the test radio would lock to the strongest of the two tx's. It sprayed too much RF and messed up the test. Of course we had all kinds of line filters on the 13V DC supply. We used this can of RF spray and just let lose with the stuff inside the sealed box to seal every possible crack. It worked like a charm
RF work was fun stuff, had you scratching your head a lot. We all dreaded the agency certification process which is always at the end of a project. I once had to make our own ethernet AUI test cables to get a pass, every commercial cable we tried failed. It cost a fortune to buy a spool of special Beldon cable, to make the test cables. A spool just for a couple of cables. What does that say about the certfication process?
Enjoy your RF conversations.
Maybe a story to lighten up this RF conversation.
As a young tech, at Motorola, I was tasked with building a test fixture that used a couple of 2-way radios inside a Hammond steel box. I guess we could have used a couple of RF SG's but I guess they did not want to commit too instruments to this task, we had lots of radios in the factory to use.
The two transmitters, were set at different RF power levels (a few dBm diff) and set to tx at different freq. the test radio was connected to the attenuated combined RF signal. The test was see if the test radio would lock to the strongest of the two tx's. It sprayed too much RF and messed up the test. Of course we had all kinds of line filters on the 13V DC supply. We used this can of RF spray and just let lose with the stuff inside the sealed box to seal every possible crack. It worked like a charm
RF work was fun stuff, had you scratching your head a lot. We all dreaded the agency certification process which is always at the end of a project. I once had to make our own ethernet AUI test cables to get a pass, every commercial cable we tried failed. It cost a fortune to buy a spool of special Beldon cable, to make the test cables. A spool just for a couple of cables. What does that say about the certfication process?
Enjoy your RF conversations.
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It has no effect on me. It's always the same few people. I know similar narrow minded colleague engineers in the real world too.
All about that. I find that the AC baddies are much more destructive on sound than what you catch on SE cables or even from having prototype without an enclosure to shield it.
Here's Folsom's general signal/small amp transformer board. It uses a CMC/DMC choke and some X capacitors, along with a dual bobbin (leakage acts like RF barrier) transformer that is PCB mount. Our new PSU for more powerful chipamps needing +/- has a filter as well.
Link to soldered up one.
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I'd argue "better sound" is actually a pretty darn complex topic, when applied to humans. Yes, a good read around this site, Olive's blog (Audio Musings by Sean Olive), and other places will give us some idea what *blinded* preferences are. But, at the same time, we live in a non-blinded world, where a suboptimal system that fits a user's ideology will oftentimes "sound better" to said individual than something designed in accordance with best practices. Which means even pathological problems, from a technical view (RFI compliance being but one of those) may even be embraced. Ultimately, we're going for some idea of "sound system that makes us happy" which is a rather idiosyncratic, multifactorial problem that relies heavily on non-auditory cues, including a lot of social priming.
It's also terrible at being generalizable past *that* or *those* individuals, which is why we really want that blinded information. Nor does that preclude adopting good engineering practices.
Of course, that's also why the premise of someone having "subjective superiority" as you well note is an utterly ridiculous concept.
A Celebration of Ignorance and Curiosity | Macrospective
Given how you've stanced yourself, the clear ignorance about engineering you've shown, and the chip on your shoulder, perhaps you may want to reevaluate? Maybe it should have an effect on you?
*This is a problem that humanity at large suffers, so it's something we all do to some extent.
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I use this part sometimes, but it doesn't always subjectively sound better: FN405-3-02 Schaffner EMC Inc. | Filters | DigiKey
That's it the dreaded turn table. I remember the solid core coax going into the quasi-peak detector and S/A test gear.
Using your ear as an instrument has its good days and its bad days = unreliable test equipment imo.
One drink and it is out of cal
That is conclusive, so under what conditions does and does it not sound better?
Using your ear as an instrument has its good days and its bad days = unreliable test equipment imo.
One drink and it is out of cal
Build your own then, if you can do better job. Post your design schematic, gerber/drill files and BOM so we can share on your experience. I'd like to learn how you wind your chokes and what caps you have chosen to use. Measurement procedures, test data is helpful. This is DIYaudio is it not.
I think I would start with the low level signal gear before I'd do any power amps, but they certainly do no harm if installed correctly.
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One thing is for certain, your amp will no longer sound the same. But you might like it. Give it a try.
Nope. I usually buy IEC plugs with filter+fuse, but they're nowhere near as complete as the beefier ones linked and shown by Destroyer.
*If you read the DS on many commercial SMPS, they also have an input filter. If it's a critical part, sealed tight containers with batteries, baby.
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One might point out that in 1968 all the op-amps referred to here were discrete modules and nothing here came from the audio industry.
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I won't use those IEC inlet filters and other things.
Commercial pre-built filters assume there is no capacitance on the AC lines and stupid stuff like that. They don't cut the subjective test, at all. The AC system is kind of a diverse ecosystem. This is why I made something to try and help tame it, that goes in the breaker box and acts to ease the recovery from complex impedance terror that is constantly going on.
Chokes should be oversized in amperes by a decent amount, is a simple rule to start with for AC.
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I find ferrite split core filters sound good and bad.
Good in that a layer of 'random' noise is reduced, and the bad is the grain and harshness you have observed.
This grain/harshness manifests as subjective overall 'hardness' with wrong sounding lows, plus mids and highs having an unnatural/artificial 'brightness' that does not belong.....highly fatiguing IME.
I have also experimentally removed split core filters from within Pro Audio gear and noted the sonic improvement....abundantly apparent when auditioning high power systems at far field listening position.
I had a Belkin multi output power filter box which added the same harshness to the overall sound.
It is noteworthy that typical class D amplifiers incorporate ferrite inductors in the output reconstruction filters and this may well be in part the reason for some listeners objecting to typical modern AV recievers etc.
Some here have advocated powdered iron magnetic components instead of ferrite....I believe their is merit to this.
Ferrite speaker magnets have their own noise also.
Dan.
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