Copyright © 1998
Cadman Enterprises Ltd
Welcome to the Graham Slee Audio Products Owners Forum Open to all owners plus those contemplating the purchase of a Graham Slee HiFi System Components audio product and wishing to use this forum's loaner program: join here (Rules on posting can be found here) This website along with trade marks Graham Slee and HiFi System Components are owned by Cadman Enterprises Ltd |
The Audio Science Review Forum |
Post Reply | Page <1 45678 19> |
Author | ||
fluddite
Senior Member Joined: 09 Jun 2013 Location: The Soft South Status: Offline Points: 416 |
Post Options
Thanks(0)
|
|
Amen to all that!
|
||
Graham Slee
Admin Group Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
Post Options
Thanks(0)
|
|
I'd learned a bit about radio frequencies studying for my 2m radio amateur license exam with the RSGB (early 1980's). However, other things got in the way, and I never sat the exam. My interest in radio communications fell away, as I had to concentrate harder on earning a living.
My next brush with radio frequencies was at the beginning of the EMC regulations, starting about 1995. I had already spent four years in broadcast, but working on audio, not the RF end. However, I knew about over modulation, and the audio circuitry had to meet tests regarding retransmission. So I had an understanding of EMC already. I attended EMC seminars and was given the responsibility of keeping abreast of EMC in a freelance position in 1997. The products I design have also to comply with EMC legislation, and they do. Although I have never been able to demonstrate it by third party laboratory testing (except for the PSU1), I have used the same self-declaration approach of most in the audio industry. Our full range of products was EMC tested in South Korea, by a distributor who was required by law to do so. Every product passed. When designing the Accession, I wanted to ensure its EMC credentials were squeaky clean and having read about Cherry Clough Consultants, and their work for the Advertising Standards Authority, I thought I could not go wrong in hiring them (quite expensive). I was also developing the Lautus interconnects, and under the same consultancy costs, these were discussed. Cherry Clough had reported on the false advertising as an expert witness, of another hi-fi firm for the ASA. After being hauled over the coals by the ASA for my explanations about the Lautus USB cable design, I explained that I was using their chosen consultant, but that made no impression on them. They'd had a complaint from a college lecturer, which topped my use of one of the most well-known names in EMC. I am willing to discuss the thought process involved in anti-nodes, which isn't a secret by the way, and the way a half-turn ferrite core works on RF attenuation. Or I can guide you to resources about it. Just let me know. |
||
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
|
||
Ernie
Senior Member Joined: 23 Jan 2014 Location: Birmingham UK Status: Offline Points: 386 |
Post Options
Thanks(0)
|
|
Hi Graham,
What did you say that the Lautus did that was objectionable? According to BS EN 61000-5-2 we need parallel earth conductors for all signal cables. We need to fit segregated trunking to our racks to get signal, ac power, and dc power cables separate then bond the equipment chassis’ to the trunking with earth straps or braids (not round cables as they don’t have sufficient surface area. The trunking (galvanised steel) forms the parallel conductor for us and having a high surface area provides a low impedance bond at high frequency. All equipment will be on the same equipotential ground plane, audio nivarra surely. Yes I am joking.
|
||
There are 10 kinds of people. Those who understand binary and those who don't.
|
||
Graham Slee
Admin Group Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
Post Options
Thanks(0)
|
|
Chris, Firstly, the Accession C has a solid ground plane, but after supplementing it with 7/0.2 equipment wire between input ground and the 0V connections local to each op-amp, the noise and distortion measurements improved. Allegedly, and according to every EMC engineer who has published anything about ground planes, what I have said is not possible. PS, dare I say it? It sounded better too!
Edited by Graham Slee - 13 Jul 2020 at 2:08pm |
||
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
|
||
Graham Slee
Admin Group Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
Post Options
Thanks(0)
|
|
Chris,
Secondly, in answering your first question, I cannot recall the exact text because I deleted the lot in a fit of rage. Graham in error #1: It had to do with the signals seen on the scope, which everybody seems convinced are neat square waves. Either every function on my scope is/was buggered, or the signals from USB (and even S/PDIF) are a tangle, which somehow, the decoder chip manages to sort out to eventually become, as near as damn it, music. Graham in error #2: My thoughts turned to the placement of ferrites on the cable and what effect it could have in cleaning up the signal. Having helped a pal out of a spot of bother at one of Nottingham University's lecture theatres (2003, when I also did pro installs), I had fitted the ends of a rather long composite video cable (ridiculously long) with ferrites. It was good enough to sharpen the image from the roof-mounted projector, which was being fed by a posh DVD player run by automation from a lectern console. I'd had thoughts of him having to use amplifiers to boost the rather weak signal, but the ferrites did the trick. I was taken aback or gobsmacked at the result. It also saved my pal's profit margin for his install. I wanted to know how such a "half turn" RF transformer had worked, and the theory is that at some (unknown) frequency, there would be an RF short circuit - the transformer producing the short. Understandably, it would not be an actual short at that frequency but would offer some attenuation. In RF a few units of dBs seem to make quite a difference and recalling how YRN's engineering chief had solved a cross-channel conflict on an outdoor broadcast - by tying a knot in the transmitter feed cable at a point he measured (the guy being a Home Office approved engineer) - it seemed that there was something about cables I needed to know. I did a lot of research online, but since I was told to take my explanation down, the online sources also disappeared. You might wish to explore the power the ASA has over the UK internet. The one thing they cannot remove is cable velocity, simply because manufacturers like Belden, quote velocity factor. However, my work was based on the lengths of the cable where the anti-nodes of particular frequencies occurred. This was how Derek knew where to tie the knot in the transmitter feeder. The college lecturer objected to this part of the explanation, although it seems regular radio communications practice. Obviously, talking about audio, and audio not being radio, I suppose he had a point, but my interest was the higher speed signals on USB. I will continue this in a bit. I need coffee! |
||
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
|
||
jupiterboy
Regular Joined: 13 Oct 2011 Location: Buffalo Status: Offline Points: 67 |
Post Options
Thanks(0)
|
|
That's interesting background. I had the sense that something had happened, but had no idea. I am also not clued in to the politics, so it's an interesting insight. I come at this as a simple enthusiast who doesn't have the cash to entertain a parade of audio components in and out of my home. Over the years I've kept and idea of the sound I like, but that has evolved along with my understanding of the design parameters that work for me. That said, gear wears out, and not being able to afford big mistakes, I tend to try and educate myself so I make better purchases. You have given me a few new concepts to read up on—overmodulation and anti-nodes! Thank you for taking the time to respond. What I can say is that an easy way to experiment with cables without spending much is to buy some bulk wire, terminate it, and see what happens. After making many of the basic discoveries, like heavier wire does change the way the low end sounds; I arrived at trying to mitigate the transient and very hot moments in recordings—like when a horn player goes into the red or sibilance. I started to realize that, particularly with valve amplification and its various added distortions, that the bloom that was generally romantic was not good when the recording was at its worst. I started reading up on true Litz wire, and the compromises and benefits of running wires in parallel—higher capacitance, lower inductance. That led me into discussion of EMC and the idea that magnetic forces outside the wire were in play. I also quickly figured out this was a big taboo in online discussion. Those that stopped with Ohms law were having nothing to do with it, and those who just liked to listen to differences did not seem to distinguish it from other marketing hyperbole. About that time I found an inexpensive wire with individually insulated wires run in parallel ribbon form. This wire really seemed to neutralize the bloom, but also reduce the added artifacts at distorted moments that were baked into recordings. I was super happy, but as I read, I realized that discussions of ideal dielectrics—those that had the least interaction with the wire—had nothing to say about conductive and semi-conductive dielectrics, which is exactly what the cheap and cheerful wires I was listening through employed. Anyway, that's more than enough insight into my comments. What I'm amazed to learn from your response and should have been obvious is that EMC applies to wires but also to the circuits of components. I suspect it also applies to a system as a whole from transducer to transducer, which I also suspect has to do with phase integrity of the sound. |
||
Graham Slee
Admin Group Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
Post Options
Thanks(0)
|
|
It may be recalled by some that bass loss can be the result of high-frequency instability, or other high frequencies wasting power. Going on what I have read in hi-fi, the correct solutions might not be understood.
It might stand to reason that a subjective improvement to the bass - in other words, it sounds nicer - might indicate that the high-frequency problem had been solved or mitigated. It appeared that way to one eighties reviewer who produced 3D RF plots of amplifiers to try and understand why one might sound better than another. I recall the Kraken, which had a following, but I also remember others saying it was as bright as ****. The RF plot of that amplifier was a complete mess. It turned out that my only point of reference in researching the Lautus (all of them) was their subjective bass response. The reason being that I had no objective way of measuring the differences. I had started to equip myself with an RF spectrum analyser. Still, I was unable to "drive it" but had started taking an interest in the work of Keith Armstrong (Cherry Clough), and I was going to continue studying how to get to the measurements required. Having had the wind blown out of my sails by the ASA, the RF spectrum analyser has been collecting dust. This goes to show that the research was based on subjective findings. Still, then it was reverse engineered by mathematics and the physics of cable velocity, and in particular, the frequencies where nodes and anti-nodes would appear. I had thought the ferrites would attenuate interference frequencies of things like switched-mode power supply harmonics and mobile phone interference. However, the calculations pointed to 100MHz and 200MHz. The ferrite positions were adjusted to the calculated nodes or anti-nodes (by now, I forget which, because I lost interest, but they are whatever 90 degrees occurs at). The conclusion of more listening tests was setting ferrites at the exact distance from the enclosure's emergence, that the 90-degree point of the waveform of 100MHz and 200MHz, related to the cable velocity, the better it sounded. The cables were then loaned out to members, and the general comment was of a bass improvement, with one or two disliking this. I then decided to take a stock USB cable, investigate its construction, using the type of dielectric (PVC) research its velocity, and then use the result to set the ferrite to the calculated position. We heard an improvement here, and owners club/forum members commented positively, so I started to market the Lautus USB cable. The explanation, which went along the lines described above, was questioned as being false advertising by the college lecturer. The ASA rejected the forum members' subjective findings and stated that I must prove what I had said by measurement or remove the explanation. The ruling only applied to the Lautus USB, but I removed references to the same description on the other Lautus pages, just in case. |
||
That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
|
||
Post Reply | Page <1 45678 19> |
Tweet
|
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |