It is not a problem you should fight with. There are many reasons to bother with amp design details, even if it is not about audible differences.
Just to mention a few: for some, it is a source of income, for others, an intellectual stimulus, for quite a number, both. Then, it can appeal to a sense of beauty, symmetry and order. Furthermore, it can be a source of intense pride. All very good reasons.
If it is about audible differences, design speakers of microphones, or pick up an instrument and start singing cover songs.
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I am very aware of company research and NDAs, but on the subject of cable directivity and how important cabling is to the electronics industry you would think there would be something out there, maybe even on the Beldon site.
The view that cables are directional at these frequencies is also met with some scorn when discussed with people in various sectors of the electronics industry...There are numerous papers and research done on PCB copper for both ridged and flex circuits, and more not in the public domain, yet numerous searches only lead me back to esoteric audio. Now I can show directivity in digital cables by adding a severe impedance mismatch (or not so severe with the simulation tools, but only manifests itself as a minor change in the wave shape due to the reflections return time being slightly different, again this is not due to grain boundaries or how the cable is drawn, but relates to a change in characteristic impedance at some point along the cable, putting a sharp bend in a co-ax will do the trick), but this would equate to a broken cable...But nothing at audio frequencies.
Phillips use to have a BIG presence in Blackburn where I live, including a big CD plant, interesting old buildings to wander round where they use to do the TV stuff (Men in brown lab coats, proper olde worlde labs (we did a lot of layout work for them where I work), sadly all gone now.
The story is Bayer had this valuable drug that sometimes was linked to death. Reports of a drug from ancient times was tried. This was derived from willow. It had no pain reducing qualities. Then out of curiosity it was processed as if morphine to heroine. The resultant new product did have pain reducing qualities. Thus the said " fact " that the Romans bit burnt willow trees to relieve pain seems highly unlikely . Reduce fever perhaps? It is processing the extract of willow as if morphine that is the alchemy. Chemistry at the time had a foot in the future and the past. As my father in law said 60 % of drugs still widely used are from the alchemy days.
Something to know. If you pick mushrooms in France or Belgium the Pharmacist is obliged to identify them for you free of charge. The training is 7 years and rivals a doctor as ultimately he or she must tell the doctor if something is wrong. That might be a conflict in medications the doctor has prescribed. I asked another Pharmacists for his opinion of doctors. His thoughts were if general practitioners they did very little. To quote " There are only about 7 really serious illnesses and they are so marked in symptoms to be obvious". Mostly a doctor is a filter to refer to a consultant or dish out unnecessary drugs. I only say this as at least it is not how the world usually sees things. If you like the Pharmacist like us here had a different view.
The problem with hi fi is most people seem to need a hi fi doctor. That is they need to be listened to. The hi fi dealers who succeed seem to understand this. For people who see the placebo qualities this is most annoying. Not all is placebo and you owe it to yourself to believe up to the point where it means spending more money. Mostly when things do sound better the reason is easy to find.
Here is something I heard on TV. No one really knows how general anesthetics work! They came from the Snake oil period. The reason I choose Aspirin is most people have heard the story of how it was thought up. The Heroine link would not be good politic to mention.
On cable sound. I would guess 20 years ago anyone who thought that capacitors of reasonable quality sounded different would need medical help.The given reason usually is dielectrics. Whilst as cable is not the same it does have dielectrics so " might " sound different. The counter argument most seem to use is that the source resistance and input resistance should be the greater factor. The next is the measurements either end will be the same. Now we hit the big deception. Who placed the measuring equipment in the place of a God ? The measuring equipment is a very mildly better piece of hi fi equipment. Reading some peoples efforts in the quest for perfection the measuring equipment is worse. This is as daft as getting a machine to judge beauty for me. Measuring equipment is tools of a trade. They are not Gods.
With digital it about transmission line . In audio is the wave short enough to be misshapened by the impedance mis match other than very large amount. This also raises the question of digital cable sounding different caused by signal distortion from refection and wave form changes.
Your analogy regarding machines judging beauty is seriously wrong, the measurements using equipment and by listening to a system are to assess its ability to reproduce music with little added to the signal as possible, a wire with gain. The beauty is in the music created by the musicians, it has nothing to do with the replay equipment. You are not measuring the music and its affect on you, you are measuring some equipment ability to replay such music.
The Big Deception is the continuing claims of magic sonic differences despite exactly zero data demonstrating them.
There is really no correlation between the shape of a digital signal and the resultant sound, either due to reflections or losses down the line....this is the same for any digital data....using eye diagrams will give an indication of possible jitter problems 9again how audible is jitter) but looking at a square wave will not tell you anything about the sound you can expect to hear.
As to the length of audio signals a little mismatch in line impedance at their wavelengths is not going to have any affect, we are talking lumped against distributed here and a huge difference in wavelengths.
I don't think anyone is suggesting measurement equipment is godlike. It's not daft at all, it should be used much the same way a camera is used at a crime scene. Sure, you could just ask the detectives to remember everything and then write it down later (or 20 years later, much the way anecdotal stories are relayed in this thread) but you'd hardly ever be able to solve a crime, because the judge is going to toss it out for good reason...it's garbage.
Human senses, memory and resistance to trickery are sh
. The only thing we can say is daft would be the opposite, relying completely on anecdotal stories and oral flatulence to determine cable audibility, because then we arrive where we are now, with enough strawmen to build a bridge across the Atlantic and not a single piece of real data that supports any of the laughable claims on cable sonics.As with health we owe it to ourselves to do research. As for the rest of the world I give up.
I went to the doctor recently and the first thing he said " It's not cancer and I don't know what it is". I went the the specialist and he said the same. I said " not all cancers are dangerous ". He looked and said I was on the right track and this one seems to be a linked thing. I was very pleased at both doctors candor.
I think the reason this happened is I am engaged with what I do and my life. It makes it easy for the doctor. I am not convinced it is not a cancer of sorts and I will keep my eye on it.
A bit of cable , who cares? Health seems to be healthier in that the unknown is possible. Capitalism has always been about theft. That someone guides another to spend money isn't unusual. Seldom do people give 10% to the poor.
No, the responsibility for providing solid data and evidence is in the hands of the peddlers. After decades of outlandish claims and absolutely zero evidence or data, anyone with half a gram of rationality in their brain will understand that it's a scam, on the order of homeopathy or psychokinesis or "speaking to the dead."
When people like van den Hul and Belt extend their frauds to encompass quack medicine, the transition is complete from run-of-the-mill scam artist to pure evil.
Good point, and one which I thought about myself about 10 years ago when I realised just how non-linear is the input impedance of a complementary feedback pair. It may reduce crossover distortion. Sometimes people forget that changing a circuit usually changes more than one of its characteristics, so 'lower impedance drive for the output stage is better' (true) gets morphed into 'wider open loop bandwidth is better' (false).john curl said:
If only life was like that where we could make people sensible. The A J van den Hul pick ups seem OK.
I use $1 HDMi cables as I can see and hear no difference. Glad to be wrong but hasn't happened yet. As my neighbour said HDMi is robust as a laid down standard ( he designs games for a living and is a published author on advanced maths ) . Scart seemed to require one grade above. That was mostly to stay in the connectors.
Cherry's (last?) paper: AES E-Library Estimates of Nonlinear Distortion in Feedback Amplifiers
is the tool the evaluate this claim
my take is that yes the lower impedance of a VAS/TIS shunt load can reduce the influence of nonlinear current loading by the driver/output stage
by about the same amount as you have "thrown away" VAS open loop gain by the shunt R - so in some cases the net difference is small enough to cause questions about the "thrown away gain" heuristic
but I think you will find that not using the VAS/TIS shunt R, applying all of the gain in the global loop still gives strictly lower distortion even if the amp's distortion is still is dominated by output stage loading on the VAS/TIS
after all its not like the shunt R is adding current drive to accommodate the nonlinear load - it all still comes from the VAS/TIS
and as usual everywhere the excess loop gain/"feedback" is higher than the loaded case you in fact get lower distortion from all causes - including Otala's TIM with practical linearized inputs - such as Bob's 1983 MOSFET Power Amplifier http://www.cordellaudio.com/poweramp/mosfet.shtml
of course you can get much higher Z loading with triple and Bob's HEC giving a virtuous circle of higher open loop linearity and higher loop gain
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Douglas Self also said this. He doesn't go above 8 mA for a VAS in general . Not to say I am right except to say low z rather than slewing is the point I have been making. The MOSFET seems to step away from convention. The 2 x 700 pF seems a horrible load. Somehow it doesn't stop the VAS driving it when still the usual 8 mA right up to 100 kHz. In fact Hitachi stated the removal of extra devices has removed various poles from the loop as a big advantage. 700 pF x 2 or 4 seems a mountain to climb. I speculated the 700 pF might be in series with a very high impedance to the gate. That is unlikely as mostly it must be referenced to the source to give a figure( perhaps not ). The drain is lumped in and called CISS. Even if we said a higher VAS voltage which we don't usually happen the low 100 kHz distortion is a mystery. The MOS FET is about 2s trans-conductance , 40 for bipolar ? Are we saying an audio MOS FET can allow negative feedback to work better? The distortion figures are 40 dB better than what looks to be true. That is 20 db worse than bipolar as a starting point ( 0.8 and < 0.08 % ), low trans-conductance and high capacitance. One would expect the distortion to be more like 1 % 100 watts 100 kHz. The truth is about 0.05%.
An unintended part of the cable debate. I am borrowing my sons Thorens TD145. It looks to be a TD160 TP16 with auto switch off. The turntable must have been modified as it has the most awful piece of twin screened ever seen. As it happens it suits me to have it that length so it stays. The Denon DL 110 should be a little bit less unhappy about the giant capacitance it must have. The coil resistance I think is about 160 R which is bellow many MM. Not the 5R of my Lyra.The good news is the wire is still shinny inside the PVC cable. It doesn't solder like OFC reminding me of my earlier statements. It took about 4 goes to get it to tin.
Feeding into a Quad 33 which for once might be OK as the DL110 output is 1.6 mV ( into Quad M1 setting ). Quad is well known for being difficult with matching . They even provide a spare unpopulated section so as to design your own perfect match. The main problem is overload margin. It is hard to find a point between not enough and too much. 1.6 mV is nice.
The arm seems ideal as the counterweight is nearly to the gimble. I dare say a bit of extra arm mass would help as it is a tad bass shy. I will let you know if it works to do that. Alignment set and Shure gauge used for 2 g.
Now the useful bit. To get a quick assessment I used a RCA to DIN adapter. Awful would not be enough to describe it. As I had another I tried that. Instantly a very big improvement. Now I have a new Rean DIN soldered on. The DIN is perhaps a little better . Sweeter mostly which is what the 110 needs. The more astonishing thing is two seemingly identical rubbish leads could be so different. There is no great mystery but it still is not easy to know without trying. No standard meter would find it.
The TD145 is beautifully engineered in a dowdy way. The TP16 although not sexy is an engineering text book design. Sadly seeing how like a Linn it is the comparison is not close. Lackluster. Good enough it certainly is and I am enjoying it. It is beautifully layered. It lacks clout I guess? the Rega P6 + Exact I used recently would eat it for breakfast.
Top Tip. The platter did not respond to metal polish. As it was so bad and I was doing the washing up it got cleaned with a stainless steel scourer. Seems to have done a good job. Lots of soapy water used.
Feeding into a Quad 33 which for once might be OK as the DL110 output is 1.6 mV ( into Quad M1 setting ). Quad is well known for being difficult with matching . They even provide a spare unpopulated section so as to design your own perfect match. The main problem is overload margin. It is hard to find a point between not enough and too much. 1.6 mV is nice.
The arm seems ideal as the counterweight is nearly to the gimble. I dare say a bit of extra arm mass would help as it is a tad bass shy. I will let you know if it works to do that. Alignment set and Shure gauge used for 2 g.
Now the useful bit. To get a quick assessment I used a RCA to DIN adapter. Awful would not be enough to describe it. As I had another I tried that. Instantly a very big improvement. Now I have a new Rean DIN soldered on. The DIN is perhaps a little better . Sweeter mostly which is what the 110 needs. The more astonishing thing is two seemingly identical rubbish leads could be so different. There is no great mystery but it still is not easy to know without trying. No standard meter would find it.
The TD145 is beautifully engineered in a dowdy way. The TP16 although not sexy is an engineering text book design. Sadly seeing how like a Linn it is the comparison is not close. Lackluster. Good enough it certainly is and I am enjoying it. It is beautifully layered. It lacks clout I guess? the Rega P6 + Exact I used recently would eat it for breakfast.
Top Tip. The platter did not respond to metal polish. As it was so bad and I was doing the washing up it got cleaned with a stainless steel scourer. Seems to have done a good job. Lots of soapy water used.
Read jcx's post. Remember the Vas output is a current shunted by a resistor (R), now think of making the Thevenin equivalent so that the resistor IS in series with the bases of the follower. The Thevenin voltage source is large and proportional to the R, so one must be careful in defining what linearity of what transfer function.
The used one I picked up is the same. Some of the packing foam has even dissolved into the mains cord as well as the cable. The RCA's are stunning worse than the cheapest Radio Shack ones.
I must admit that I am a believer in new-age medicine. I regularly take vitamins over the MDR amount, especially vitamin E, where I take 1000IU's/day. Can't hurt and seems to keep me younger looking and healthier than many of my contemporaries. Maybe not, maybe it is just my imagination? However, I will continue to take my vitamins for as long as I live, why mess with 'success'? Now what about people that I know who sell, along with their audio 'improvements' some source of 'health' improvement too?
Has anyone (or everyone) met and talked to Dr. Van den Hul? Most here knows that he works with phono cartridges and wire. VDH is an engaging guy. He likes to talk, and explain things if he can. He also doesn't bother to put his findings up in a refereed journal, as I guess he just isn't interested in the fireworks that would start. Why bother, if you find something interesting that works? I am surprised that many of you who have met him do not remind SY that he is going over the wall with his accusation regarding VDH's honesty.
Has anyone (or everyone) met and talked to Dr. Van den Hul? Most here knows that he works with phono cartridges and wire. VDH is an engaging guy. He likes to talk, and explain things if he can. He also doesn't bother to put his findings up in a refereed journal, as I guess he just isn't interested in the fireworks that would start. Why bother, if you find something interesting that works? I am surprised that many of you who have met him do not remind SY that he is going over the wall with his accusation regarding VDH's honesty.
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