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Everything posted by dave

  1. What about ferrite powder? Some EMC test chambers are lined with ferrite.
  2. And remember to change the voltage selector. (didn't mention in post, never assume anything)
  3. I still love my Wharfedale Dovedale iii. I have been running them from an SE ECL86 stereo-gram amplifier for 8 years now, I had a little break, and also swapped out the output transformers for some bigger ones, tightened up the bass, and beter treble extension, and got them back together again, and I just love them, the tweeters are very unforgiving of crappy solid state treble, but give it a few clean valve watts, just lovely. Most Dovedales the woofer rubber goes hard and eventually disintegrates, but they still sound ok, I have refoamed / rubbered 2 pairs now, helps the LF extension, the tweeters sometimes go open circuit, as aluminium voice coil wire reacts with the steel magnet, the 3s are an earlier version with no tone switches on the back, a bit brighter, some prefer them, I prefer the later version. Am thinking of doing some tweaks, but they are lovely stock, so I am not sure when....
  4. This video is by the Monty, referenced earlier, and is quite clear and informative. Totally respect he really ought to know what he is talking about as he has done a lot of software I respect, but as a hardware person, the zero order hold is in there somewhere, and I would still rather do with higher sampling, and less invasive reconstruction filter.
  5. These people don't seem to have a problem with almost brick wall filters. That's my current stumbling block, I don't intellectually trust anything less than about 96kHz sampling as being capable of approaching transparency, i.e. having the filtering artifacts at least a little out of the way. With (32), 44.1 48 kHz sampling the reconstruction filter is absolutely necessary to get that nice flat sine wave frequency response up to 20kHz, with higher sampling rates that necessity reduces as the sampling rate increases.
  6. Keeping up with the newest, I quite like the Townshend idea, and have made my self a couple of pairs, don't have an opinion at the moment, amused by the anti-cable which seems to go off in the opposite direction.
  7. Humor dave moment.... I used to love laying out PCBs at work, using the decent cad system, it was just so satisfying, all the little tracks moving around and the power of the system after using some lesser systems...
  8. dave

    Second Systems

    NS1000 and Sony TA F730es at one end of my office is a kind of "normal person" stable reference counterbalance and sanity check, gets used for testing things and listening sometimes, its quite good, but missing the valveyness of my "comfy sofa" system at the other end of my office.
  9. Ooo audiostool, haven't tried that. Must install toddlers potty between speakers, do I need to ground the fresh stool? And how long does the effect last?
  10. Scientific method should not be confused with science, which seems more like a religion to me.
  11. Providing spectral plots imo would be entirely reasonable, easy to do and should conclusively prove that 4's cable is indeed reducing "RFI" travelling along the wire. But this would then raise the slightly awkward question of why was the noise there to start with, which way is it going and what is effecting what, especially if it is indeed going between two bits of kit from the same manufacturer (as I assume). Maybe this should move to the measurements Tech corner? M&S
  12. It may have some kind of circuit breaker for protection of speaker outputs (Google).
  13. You're missing out there too then . I put off buying a smartphone for years as a totally unnecessary expense but really wouldn't want to be without one now. I would put it off as long as possible. I love mine, but I found after a while the 3g was making my head hurt, as in physical headache, 4g is a bit better, but I leave them turned off for the most part unless I need it, then turn off again. I got a head ache last time I sat in a hall of people (and all there smart phones). 5g worries me, no one needs a phased array following them around.
  14. Out of curiosity, could you explain quite what you mean by this? I am not sure what technical level you are asking at. At each end of the co-ax is a 50 ohm resistor between the core and the screen. At the source end, a current source made from a folded cascode, at the output end a tantalum capacitor for DC blocking (oscons weren't invented), It ran from 12 volts and used about 500mA a side, and could pass 2v RMS. There was a modest measurable distortion. I used it for about 5 years, I don't use it now as my stereo is much more complicated, and more for fun, than the earnest researches of younger days. They are a little impractical. I consider building it into a custom interface between my various projects but haven't, due to the time constraints and extra development complexity.
  15. Hello 4legs. I have spent a bit of time in the head fi, ( since you bought it to my attention, and intended to spend some more). I am alway interested in the opinion's and experiences of boots on the ground designers and tinkeres. Romy the cat seems to be afflicted with dirty electricity in a similar way to the Rob watts. I am not convinced personally that I am having this experience myself however. Once upon a time (many moons ago) a few years after I finished studying communications (RF) at university, I decided to make a 50ohm terminated active interconnect. It took me a year or so to realise it was actually doing something, as I made improvements elsewhere in my setup. Interestingly to me the sound quality changes are similar to the changes described earlier, darker, but smoother, and more detail. I did think to commercialise it, but I am just not commercial. Also I am sort of in denial as to why it worked, could be even order distortion?. I really don't think it was RF though. As people with lots of money, i.e. military, and phone companies are very interested in radio communications there are many well developed test instruments. And they are not that expensive compared to some high end audio gear. RFI is relatively easy to measure..... Why the absence bar a few forum posts and circumstantial observations of any concrete cause and effect (To my limited knowledge). I am fine with that, there are lots of things that are not really understood.
  16. Thanks, I have an hp8591e that I rescued from work, and a digilent analog discovery, very versatile tool for the lower frequencies. I live in a dip, so RF is not to bad, apart from local transmitter on 96MHz, but the pumping station down the road, I am convinced is doing strange flickering on the mains, suspect a VFD beating with the 50Hz.....
  17. This is an entirely reasonable perspective IMO (of wich I am generaly sympathetic) for some one who obviously has skills in electronics, but who does not hear differences in cables. (This is not supposed to be an attack, I am not sure if there is a name for this type of audiophile, maybe Serge's * would suffice?). But then again, there are people who do hear what really are quite subtle effects. There does not seem to be much widely held "belief"? in the effects Mr Chord seems to suggest, this is the first time it has been thrust into my consciousness, enough to give it serious consideration. It is an interesting theory, but it does seem to have some holes in for me, mainly the known effects of demodulation V what seems to be some amorphous "RFI harshness field". And yes, I have spent countless hours with headphones plugged into multi k£ Rhode & Schwartz EMI receivers, debugging all sorts of emissions problems, mostly caused by inadequate screening curiously.... and occasionally immunity. Anyway, I will be now on the lookout for for this possible cause and effect, and curiously again, I have just been given a DA03A, which I have connected to my TV tuner for DATV radio 3 reception. My stereo has been sounding really quite odd at times since, I have turned it off now and some kind of normality has been restored. (maybe, or was it a coincidence) Oh wait, I used TOSlink. *Serge = certified measurist
  18. It would not produce any output if it was not fed some RFI, I mean digital data.
  19. I used to be a bit suspicious of them when I was a yooth. Now I design high speed amplifiers driving peculiar loads down, shock horror, wires, I see the true need and purpose of the zobel network. As the frequency extends towards the low MHz, it's a jungle. At one frequency the load is open, at another a dead short. It is no wonder the poor amplifier gets confused and starts oscillating. The zobel is an attempt to isolate the amplifier from the anarchy and give it a more predictable environment for its feedback to work, without getting its knickers in a twist.
  20. Early ac coupled solid state amps use a solitary transistor at the input.
  21. Maybe you could qualify that, I thought it was only strange people like me trying to escape from that circuit.
  22. One of the hifi mags, can't remember if it was choice or news, did an RF immunity sweep in their testing once iirc, must have been 20 years or so ago, possibly coinciding with the CE mark. Doesn't seem to have caught on though.
  23. I am not convinced of anything till I have proved it to my self in a quasi controlled manner.... I have no axe to grind incidentally, and thanks for your responses, you seem to be making things that make people happy, and that can't be bad. I feel my self being drawn in to the head fi for a number of reasons, I may be some time, I am a slow reader......
  24. er that would be me actually...