Popular Post One and a half Posted February 3, 2018 Popular Post Share Posted February 3, 2018 On thoughts of reducing RFI and EMC offenders in the home and their influence on digital audio, the victim has enough resilience to ignore that interference, but why make it easy for noise to propagate further. There are so many SMPS and RF generators in the home where will it ever stop, it's just not possible to remove them all, but at least identify them and route audio power and signal cables away from them to minimise coupling. Distance is very good, ferrites are a good weapon. Armed with a portable LW radio tuned around the 153kHz mark (the closest to the audio band as I could tune) lets set on a hunt to see which noise maker is the worst. List of items tested HP Z800 tower style workstation Lenovo mini computer i7 HP Laserjet M252 network printer Topaz 1000VA transformer TPlink 24 way network switch Generic 12V 2A SMPS Dell 24in monitor Mac mini 2010 vintage QNAP 419P NAS Asus wireless repeater Mutec MC-1.2 USB to S/PDIF converter Accuphase E-450 integrated amplifier iPhone 8 plus Based what I heard on the radio, some items were disconnected immediately. All devices were in their normal operating condition or in standby mode like the printer. Have a guess as to which devices were the worst and which were the least noisiest. No need to grade them all, just the worst or best will be fine. I was quite stunned as to which were really quiet. Sonicularity and fas42 2 AS Profile Equipment List Say NO to MQA Link to comment
One and a half Posted February 3, 2018 Author Share Posted February 3, 2018 Yes, I'll leave the post up for a few days - week then reveal! asdf1000 1 AS Profile Equipment List Say NO to MQA Link to comment
One and a half Posted February 3, 2018 Author Share Posted February 3, 2018 The noise picked up by the radio is energy that's escaped the Faraday cages, so fat lot of good that does, and the 'best of intentions' as far as EMC Class B emissions for conducted noise. The reason for the 'best of intentions' statement, for testing EMC from equipment statements is dubious to non existent in the real world. Ever noticed the first part of an IT device packaging that has printed material is not the user manual, but the obligatory EMC statement, that the device complies with FCC et al. Throw this in the recycle bin amid all the other packaging materials. If that energy is picked up by the radio, how much of that energy is capacitively coupled to the ground plane at the source, where the energy is lot more intense. Some may argue that RF frequencies don't matter for audio bands, however, audio relies on very small voltages to extract minute details of recordings, and if coupled RF/common mode noise/differential mode noise is added to signals, then RF emissions do matter. SMPS are a classic noise generator, they have no place near audio systems. Sure, some SMPS are just as quiet as a linear (like one in a million designs), the piece of paper shipped with it says so, hahahahaha! Pull the other one. Another classic example is to use a laptop -> (any) USB cable -> DAC and listen. Add in a (ISO)Regen/Intona/Micro 3.0/sOTMxxx to the chain and listen again. There's a reason why USB fixers still sell. Ethernet is not off the hook either. The Jim Brown site is quite a good reference, it will take some time to digest. Hams are very keen to remove RF as it impacts on transmissions, however 'small' these usually IT devices are, they create a lot of havoc. I doubt an SMPS is in the same radio shack as the rest of the gear they use. AS Profile Equipment List Say NO to MQA Link to comment
One and a half Posted February 3, 2018 Author Share Posted February 3, 2018 4 minutes ago, mansr said: Remember that a radio is specifically designed to pick up these signals. A device designed to not pick them up ought to be influenced to a lesser degree. Yes, it's the back door that's the main concern for one and how much RF is ignored. AS Profile Equipment List Say NO to MQA Link to comment
One and a half Posted February 4, 2018 Author Share Posted February 4, 2018 3 hours ago, Spacehound said: Sorry, my post above screwed up and I can no longer edit it. Well yes, if you are talking about noise generated inside each box then a Faraday cage won't stop it interfering with itself. And as has been pointed out, RFI is so far outside the audio band, and the usual frequency response of amplifiers etc. that it simply won't have any effect. Regarding 'minute details' the only 'minute detail' involved is the output from a moving coil cartridge, which I have already covered. Here's a table taken from a you tube video from Hans Beekhuyzen "Audio Hygiene 3 Interconnects". This table, very simply stated is a dynamic range table and the bits required to create that range. We only have 2V nominal to work with as a line out, so here's the able to the bare minimum of 20bits, of course most hires audio files are 24bit PCM. Fine details are specs of 'dust', and the audible ones, often discussed here at which level perception starts is another issue. At -72db these are mV and -96db in the microvolt ranges. For a DAC to produce these levels, it would infer that these values are clear of noise to be reproduced by the DAC correctly. When RF is free to propagate at will, what guarantee do you have that these voltages are out of the audio band and won't cause playback issues in a DAC? A DAC of course is where D meets A. AS Profile Equipment List Say NO to MQA Link to comment
One and a half Posted February 5, 2018 Author Share Posted February 5, 2018 2 hours ago, Spacehound said: While I agree about it being analogue, it's a representation, as you say. It's not somethin that you have to amplify or whatever accurately. Silberman is only a snake oil cable manufacturer so I take no notice of him. As for the others, Rankin talks pure bollox at times. Swenson is better but I think he is mistaken on some things. Anyway, "appeals to authority", of which you seem so fond, are a logical fallacy because they prove nothing either way. So are these references worthless? Footnote 1For those who are truly interested in diving in deeper... High Speed Digital Design: A Handbook of Black Magic Howard Johnson, Martin Graham, 1993 High Speed Signal Propagation: Advanced Black Magic Howard Johnson, 2003 Electromagnetic Compatibility Engineering Henry W. Ott, 2009 EMC for Product Designers, Fourth Edition Tim Williams, 2007 Grounding and Shielding: Circuits and Interference Ralph Morrison, 2007 Digital Circuit Boards: Mach 1 GHz Ralph Morrison, 2012 Solving Interference Problems in Electronics Ralph Morrison, 1995 Noise and Other Interfering Signals Ralph Morrison, 1991 Read more at https://www.audiostream.com/content/theres-no-such-thing-digital-conversation-charles-hansen-gordon-rankin-and-steve-silberman-p#RSUrc61YKh1Tmc9z.99 AS Profile Equipment List Say NO to MQA Link to comment
One and a half Posted February 6, 2018 Author Share Posted February 6, 2018 16 hours ago, motberg said: FWIW.. I have a TriField meter.. from memory, worst offenders in my room are the LPS´s, I wrap these with a few layers of Mumetal if they are close to anything I think may be sensitive. However iirc 18 CM distance = 2 layers of 1.5mm Mumetal. Also 1 large sheet Mumetal =$25 USD .. so.... I have a strange situation on the analog side... I think it is related to tube gear only.. if I have a tube preamp connected with non-shielded XLR or RCA cables, I get an intermittent audible whistle at 7.5kz (similar sound to what I think I hear sometimes from a computer monitor). If I use balanced shielded cables, then this whistle seems to be reduced to near inaudibility or eliminated. I am not sure if it is the tube preamps, but seems to not happen with SS preamps... I have tried trouble shooting the exact source with no success. I think I had the same problem with 4 different tube preamps, though again, not sure if that is the source due to the intermittent nature of the whistle makes it difficult to positively identify (not only that, is that I think during troubleshooting I start to hear the whistle and I am not sure if it is really present.. the frequency seems similar to what is described as tinnitus..). I was thinking it should be pretty easy to test RFI effects by introducing the offensive stuff into the system and record silence into a DAW equipped battery laptop, but haven't yet sketched out the test procedures or checked the noise floor of a typical laptop mic input (could always use a home studio USB ADC I guess). That way, no need rely on hearing sensitivity, transducer accuracy or eliminating masking during music playback. This is an interesting problem you have and out of this thread but related. Could you copy the contents and start a new thread? You would obtain better focus and outcome. AS Profile Equipment List Say NO to MQA Link to comment
Popular Post One and a half Posted February 7, 2018 Author Popular Post Share Posted February 7, 2018 The final reveal, like the reality renovation shows... Here's the list HP Z800 tower style workstation Lenovo mini computer i7 HP Laserjet M252 network printer Topaz 1000VA transformer TPlink 24 way network switch Generic 12V 2A SMPS Dell 24in monitor Mac mini 2010 vintage QNAP 419P NAS Asus wireless repeater Mutec MC-1.2 USB to S/PDIF converter Accuphase E-450 integrated amplifier iPhone 8 plus Without a signal strength meter on the radio, all I had was a this is noisier than thou and compared directly. The bad items are red, tolerable in yellow, made no noise are green. Green Devices Accuphase E-450 integrated amplifier iPhone 8 plus Mac mini 2010 vintage Topaz 1000VA transformer TPlink 24 way network switch Yellow Devices Asus wireless repeater - Beyond 600mm distance it was dead quiet HP Z800 tower style workstation - Only noisy if the radio was right up against the computer Red Devices Lenovo mini computer i7 HP Laserjet M252 network printer Generic 12V 2A SMPS Dell 24in monitor QNAP 419P NAS Mutec MC-1.2 USB to S/PDIF converter Finally when the QNAP NAS was shutdown and off, there was still noise coming from the SMPS. Once the SMPS was disconnected from the AC, and allowed time to discharge, did the noise finally vanished. This is now disconnected. The LaserJet would be the loudest noise and several frequencies. It's on a different circuit in the house. The Lenovo mini PC was let down by its SMPS 20V 5A, not used anyway. The Mutec was very bad, very similar to the Generic SMPS, lots of frequencies and the strongest noise from the left of the device where the Meanwell SMPS is fitted. The MC-1.2 can work off USB power and this is how I left it. After this test was completed, I had to head off away from home, so couldn't check the before and after on the main system. asdf1000 and Spacehound 2 AS Profile Equipment List Say NO to MQA Link to comment
One and a half Posted February 7, 2018 Author Share Posted February 7, 2018 3 hours ago, Ralf11 said: Was this an AC powered radio? You mention the circuit the LJet was on being a different one, so RFI might be supplemented by line transmission (?) The radio was battery powered. The Laserjet is on a different circuit in the house away from IT equipment which is fed by a 230V/110V 2kVA transformer. Once the printer was off, the 230V cable was pretty quiet. AS Profile Equipment List Say NO to MQA Link to comment
One and a half Posted February 7, 2018 Author Share Posted February 7, 2018 2 hours ago, sandyk said: Garry In my case , I need to have an indoor DTV antenna with a low noise MHA not far from my W10/64 PC. The USB leads to the mouse and keyboard especially , cause quite a bit of interference to DTV reception, with clip on ferrites not much help. Alex Several turns through the ferrite would help? AS Profile Equipment List Say NO to MQA Link to comment
One and a half Posted February 7, 2018 Author Share Posted February 7, 2018 @SandyK and @Spacehound, can we bicker about something else? The Computer Audiophile 1 AS Profile Equipment List Say NO to MQA Link to comment
One and a half Posted February 7, 2018 Author Share Posted February 7, 2018 1 minute ago, sandyk said: The clip on ferrites I obtained are too small to do this. Wireless mouse and keyboard? They operate at different frequencies maybe out of the reach of DTV. AS Profile Equipment List Say NO to MQA Link to comment
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