Nigel, feel free to share these graphs.
Also feel free to share the preamp that resolves fractional change on .34nV of noise.
Carbon comp has great peak current capability because of its large cross section which is why its used in pulse applications. However even the resistance values change a lot with the pulses and with humidity and time.
A 5 Ohm resistor generates the same thermal noise as any other 5 Ohm resistor. The noise increases with things like voltage drop/power. CC resistors increase noise faster than film resistors. Also the CC resistors have the highest distortion of any type, way higher than metal film or wirewound.
A 5 Ohm resistor generates the same thermal noise as any other 5 Ohm resistor. The noise increases with things like voltage drop/power. CC resistors increase noise faster than film resistors. Also the CC resistors have the highest distortion of any type, way higher than metal film or wirewound.
Nigel, feel free to share these graphs.
If I show without the cartridge there is more of what you would expect . With cartridge it is less clear cut . In fact the CC looks better in places . Perhaps this is logical as it is a pure resistance more or less . The - 55 db line is from a previous test .
Two things I was told 40 years ago was don't use zener didoes and carbon composition resistors, both have unacceptable noise . This all goes to prove there are no short cuts to knowledge . A simple filtered zener seems to be 10 dB quieter than an LM317 . That was using a simple Panasonic 10 uF FC as filter .My old boss took Warfarin ( rat poison ) . He developed cancer of the liver which probably was linked . When he asked about alternatives Aspirin was recommended . He was furious . When he asked why it had not been recommended before he was told because people wouldn't believe it to be a true medicine . With resistors how humans research things is curious . With medicine they do the same . Always question things . They seldom know as much as they give you to beleive .
There is a line in a Lou Reed song..."Don't believe half of what you see,and none of what you hear".
Level of noise is one consideration, the spectrum of that noise is another consideration.
Dan.
Dan . It seems at that point ears work best . Doubtless it can be measured and I did find ways . The beauty of a basic test is to say nothing obviously wrong , listening test possible . Some people talk very sagely . Reality is they will find it very difficult to bring forward meaningful data when the bigger picture is presented . Julian Vereker walked up to me one day and said in the middle of a hi fi show in front of baffled visitors . " I don't know these people , I do know you " . He went on to say " did you ever hear hiss with my equipment when a record was playing " ? I said no , he beamed and walked away . As he walked he said " they say my amps have too much hiss " . He did me a favour as many things in the bigger picture are not correct and nit-picked stuff is already fine .
As you say Dan noise spectrum . CC resistors are pink . It is nice but slightly Kodachrome . Foil is like someone cleaned the stylus . Dentist clean that is .
When I first met J V he said short of using liquid Nitrogen he was at a loss to do better . The Naim used 5 transistors in paralell to get a reasonable result (single ended which gives at least 3 db better I guess than an op amp ? ) . I suspect something was not as good as it should be as with that 78 dB should be possible . Naim was not noted for low noise . Maybe the 5 x 15 R emitter resistors didn't help ?
Here is the test without PU .
As you say Dan noise spectrum . CC resistors are pink . It is nice but slightly Kodachrome . Foil is like someone cleaned the stylus . Dentist clean that is .
When I first met J V he said short of using liquid Nitrogen he was at a loss to do better . The Naim used 5 transistors in paralell to get a reasonable result (single ended which gives at least 3 db better I guess than an op amp ? ) . I suspect something was not as good as it should be as with that 78 dB should be possible . Naim was not noted for low noise . Maybe the 5 x 15 R emitter resistors didn't help ?
Here is the test without PU .
Yes, ones ears are the final arbiter.
Ok, useful subjective descriptions.
Hmmm, I have found an interesting way to change the perceived noise, though I am having troubles measuring it.
ARTA running averaging of 2000 or so trials is showing up differences in VLF noise, interestingly.
Subjectively the difference is sort of like reduced jitter/imd, with deeper solider bass and clearer mid/highs.
L/R and depth imaging markedly improved, overall more realistic sound but no FR changes measured.
Dan.
Very true . Popcorn and flicker noise come into it . I read recently don't reverse bias transistors even with a diode test as it increases noise . The gentleman used BD139 which is a rather obvious device to use and plentiful . I used BD135/6 in the zener PSU with very good results . VLF specifically .
Nigel
Nigel
That data has insufficient averaging to show any statisticly significant difference. I've posted the LNL paper on resistor noise several times, an excellent summary of theory and measurement of excess noise. At 0 DC current the noise of all (non-pathological) resistors is the same for any given value.
Even the 40yr old 1K CC that had drifted to 1200 Ohms that I looked at a couple of weeks ago was still exactly at theoretical value (now 1.2k)
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Hi Scott . For pick loading perhaps it doesn't matter too much if it drifts ? For RIAA it matters greatly . The main point for me is do checks and reject obviously daft uses .
As you say CC drift .
Here is the best way and cheap . Carbon film shown ( fine ) . Metal film possibly better . From the same bandoleer should ensure the spiral is the same .
As you say CC drift .
Here is the best way and cheap . Carbon film shown ( fine ) . Metal film possibly better . From the same bandoleer should ensure the spiral is the same .
Whether two close resistors are inductively anti-phase does not depend on which way round they are but how they are wired. This is because if you invert a helix you get exactly the same helix. This issue keeps cropping up. Do people never learn?
If the two resistors have the helix cut nearer one end then inverting one of them may reduce mutual inductance and so reduce the possible net inductance reduction i.e. it will do no good and may do harm!
In any case, just how significant is resistor inductance at audio frequencies? VHF maybe, UHF certainly, but 20kHz?
If the two resistors have the helix cut nearer one end then inverting one of them may reduce mutual inductance and so reduce the possible net inductance reduction i.e. it will do no good and may do harm!
In any case, just how significant is resistor inductance at audio frequencies? VHF maybe, UHF certainly, but 20kHz?
If one could find a manufacturer that cuts the helix in the opposite direction to all the others then one could "build" lower inductance resistor combinations.
That manufacturer could even legitimately claim that "their resistors" reduce inductance, provided of course that they took the time to explain "how to" do it.
There might be manufacturers that double helix the cut so that the first half turns are in the opposite direction to the other half turns. This would be very easy to implement, but I am not aware of any manufacturer claiming advantage from doing this in "ordinary" metal film resistors.
That manufacturer could even legitimately claim that "their resistors" reduce inductance, provided of course that they took the time to explain "how to" do it.
There might be manufacturers that double helix the cut so that the first half turns are in the opposite direction to the other half turns. This would be very easy to implement, but I am not aware of any manufacturer claiming advantage from doing this in "ordinary" metal film resistors.
I was talking about noise, at 0 DC current (i.e. cart load) a 1k CC and the best film are both 4nV/rt-Hz in voltage noise, this comes from basic thermodynamics.
As a parallel load it is actually better to express it as current noise, in any case you can do the math 1K in parallel with 7 Ohms adds infinitesimal amounts of noise in the first place.
Good point . It was in a radio Hams book and I fell for it . The displacement forced by the geometry might help . Perhaps something else accounts for what I suspected helped . Noise will be by random distribution . Could it be it produces a nicer type of noise ? It seems far fetched to say it reduces noise , could it ?
I don't mind being wrong . Learning is what it is all about .
That could be the key.
I am finding that changing VLF (<<20Hz) noise spectrum changes subjective sound, not always for the better, but it can also do so very pleasingly.
Dan.
As a general rule amateur radio does not suffer to quite the same extent from the circuit 'blindness' found among audio people. The book you read may be an exception. In amateur radio the big blindness is antennas and transmission lines - myths and misunderstandings abound. Even some professionals and academics make elementary blunders.nigel pearson said:
Using two resistors where one will do will make no difference in most cases. In a few cases (strong signals - many volts) you may get less distortion due to nonlinearity or thermal effects. Noise will be about the same. Apart from this, I suspect the placebo effect?
A good question.
Personally, I think it's still 99% about the topology and its execution, assuming one hasn't made any obvious mistakes somewhere else. I think knowing which transistor makes a good friend to another in any topology is way more important than placing one's resistors.
Samuel Groner has some good material on that (SG-Acoustics · Samuel Groner · Home).
Also, Scott, if you haven't seen it, do take a look at his somewhat lengthy test of op amps. I did and agree on some points, but disagree on others; a good example of the measurements saying one thing and practical experience and human ear disagreeing.
Frank, I also expect you to study that same text, I'll drop around and question you on this.
I see at lot of noise in the sub 50 Hz region . I used to think it was
sub harmonics and was happy with that . Then someone said stable oscillators do not have sub harmonics . Without research I accepted that . There is a possible exception . The modern mains electricity system is feed by some small generators these days , perhaps some VLF comes from this ?
In real life music with good 16 Hz performance sounds more open when phase is correct .
It is possible that 2 resistors produce some statistical cancellation . The noise is whiter ?
No. Their noise will be uncorrelated, so two sources of white noise sum to produce: white noise!
Any low frequency 'noise' on mains comes from lots of things being switched on and off at random; some of them may impose various amounts of DC too. It is just about possible for a generator to produce sub-harmonics - this can be a sign that the bearings are not long for this world!
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