Hi actually not.
Bicycle has the best ratio in terms of input Jules for produced work. I think 1:7.. No engine can achieve that. For instance in agriculture, for 5 input calories in form of motor fuel, output is 1 calory. But If You are using human power and manual production that is opposite. For 1 calory input outcome is 5 cal. That is 25 times more...
So You can drive a bike with one cube of sugar energu with a distance that no engine can beat with same input energy
I doubt the Ferrari drivers care about this.
Any experience with these?
GRAPHITE RESISTORS
I've been using them in loudspeakers crossovers for a while with great results! Really great.
Maybe later I will try them as I/V resistors on my PCM1704K based dac. Now there's a hand wound copper wire 1R7 resistor.
GRAPHITE RESISTORS
I've been using them in loudspeakers crossovers for a while with great results! Really great.
Maybe later I will try them as I/V resistors on my PCM1704K based dac. Now there's a hand wound copper wire 1R7 resistor.
My guess would be that a significant part of the resistance of such a 'graphite' resistor is the contact between the copper and the graphite. Making good contacts is part of the secret of making a good resistor; resistor manufacturers have decades of experience in doing this reliably. Unlikely that home made resistors will be as good.
My guess would also be that 'graphite' resistors have high excess noise, like carbon comp. Possibly hgh distortion too.
Note that such a long thin resistor element would have highish inductance, the very opposite of the 'non-inductive' claim in that article. Fortunately, in most audio applications this does not matter.
My guess would also be that 'graphite' resistors have high excess noise, like carbon comp. Possibly hgh distortion too.
Note that such a long thin resistor element would have highish inductance, the very opposite of the 'non-inductive' claim in that article. Fortunately, in most audio applications this does not matter.
My take is there’s not best resistors, it depends in where it’s being applied to.
Graphite may work well in your speakers as there’s lots of current & voltage flowing across it but for I/V might not work too well. Example many rave about foil & rhopoint wire wounds but in my case I found the best sound using shinko. Moral of it is you got to try with many varieties to arrive at the results that your looking for Fralippo.
Cheers
Graphite may work well in your speakers as there’s lots of current & voltage flowing across it but for I/V might not work too well. Example many rave about foil & rhopoint wire wounds but in my case I found the best sound using shinko. Moral of it is you got to try with many varieties to arrive at the results that your looking for Fralippo.
Cheers
A while back, I fitted standard Dueland graphite resistirs to my X-overs. They made for, as you suggest, a surprising improvement. Unlike many Dueland products, they were not that expensive so it seemed a waste of time to DIY them esp as Dueland knows what it is about build-wise.
Graphite resistors are, contrary to DF96's guess, widely recognised as having a low inductance. They also have a positive temperature coefficient, making them - it is claimed - suitable for the relatively high currents encountered in passive X-Overs as they counter thermally-driven modulation in voice coil impedance. See e.g. Dueland's web site on this.
OTOH, though the claim in the Danish paper you cite that the effect is too small to matter might be correct in some cases. it is backed only by a subjective report on one - and only one - exotic and now unavailable tweeter in an unknown circuit. Your experience, like mine, is different and just as valid.
I'd strongly recommend against using them as I/V resistors; they are designed for and at their bext in X-Over circuits. I'd go instead for Charcroft Z-Foils, which, though not cheap, are cheaper than the Duelands, much easier to fit and electrically more suitable.
HTH
D
The Duelands are the only commercially produced pure graphite resistors I know of. They too are long and thin, very much like the home-made versions described. OTOH, they are not wound.
Measurements made by Martin Colloms and cited on Dueland's web site suggest that, while they do not have the lowest inductance of the tested range, they are still low. See:
http://duelundaudio.com/wp-content/.../02/Resistors-vol5-no-3-HIFICritic-Hi-Res.pdf
I did not make the measurements and note that no frequencies are given. If you think Dueland/Colloms are wrong, please take it up with them.
D
How does one "wet" graphite to make a secure electrical connection? I think only a mechanical connection is possible, and it'll be very nonlinear with temperature and voltage.
There's graphite and then there's graphite: the soft stuff isn't mechanically formable without a binder. The graphite used in carbon composites seems like a different form that felt rough and abrasive in the few samples I've ever encountered.
Carbon has a bewildering variety of stable forms; one interesting type is vitreous or 'glassy' that may or may not be conductive. It's extremely hard and chemically stable, but I don't know if it's electrically conductive to any degree. Can it be made into films?
https://www.2spi.com/catalog/documents/Glassy-Vitreous-Carbon-Info.pdf
Graphene is very electrically conductive, but try to obtain samples suitable for actual resistors. Soft graphite >is< graphene in mass quantity, but has to be isolated to single-atom sheets to be realizable. At the moment, real graphene is extremely hard to work with, either inside or outside the laboratory.
At any rate, carbon seems intuitively a non-linear substance to produce a highly stable resistor, even though it was once the material of choice for cost-effective design as either composition or the much more stable film. While I'm very skeptical of this present conversation I'll continue to follow it just to see what we may be able to learn about this alternative.
There's graphite and then there's graphite: the soft stuff isn't mechanically formable without a binder. The graphite used in carbon composites seems like a different form that felt rough and abrasive in the few samples I've ever encountered.
Carbon has a bewildering variety of stable forms; one interesting type is vitreous or 'glassy' that may or may not be conductive. It's extremely hard and chemically stable, but I don't know if it's electrically conductive to any degree. Can it be made into films?
https://www.2spi.com/catalog/documents/Glassy-Vitreous-Carbon-Info.pdf
Graphene is very electrically conductive, but try to obtain samples suitable for actual resistors. Soft graphite >is< graphene in mass quantity, but has to be isolated to single-atom sheets to be realizable. At the moment, real graphene is extremely hard to work with, either inside or outside the laboratory.
At any rate, carbon seems intuitively a non-linear substance to produce a highly stable resistor, even though it was once the material of choice for cost-effective design as either composition or the much more stable film. While I'm very skeptical of this present conversation I'll continue to follow it just to see what we may be able to learn about this alternative.
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It appears that 'low inductance' is being used here to mean 'not too much more inductance than a wire of similar size'. In that sense almost any non-wound resistor will be 'low inductance' so the phrase has little meaning. Fortunately, for audio it doesn't matter anyway. In reality the dominant inductance is likely to be the circuit loop in which the resistor appears.
Anyway, it seems to me that what are essentially carbon comp resistors would be a poor choice for I/V unless you want to add a little distortion and noise. CC is a poor choice for any resistor, unless you want excellent overload handling - which is why they are still made for professional use.
Anyway, it seems to me that what are essentially carbon comp resistors would be a poor choice for I/V unless you want to add a little distortion and noise. CC is a poor choice for any resistor, unless you want excellent overload handling - which is why they are still made for professional use.
Can´t imagine any mechanism by which a long thin carbon bar, basically same as a piece of pencil graphite lead, can "improve" or even modify at all any sound electrical signal going through it.
5 cm of such resistor will have exact same inductance as a 5 cm piece of copper wire, both irrelevant compared to inductance of wire connecting amplifier to speaker ... which even if much higher is still inaudible.
And both pale compared to any dynamic speaker voice coil inductance, which is orders of magnitude higher ... and which *does* influence sound.
But wire/graphite inductance?????
Only "improvement" I can imagine is through Faith.
5 cm of such resistor will have exact same inductance as a 5 cm piece of copper wire, both irrelevant compared to inductance of wire connecting amplifier to speaker ... which even if much higher is still inaudible.
And both pale compared to any dynamic speaker voice coil inductance, which is orders of magnitude higher ... and which *does* influence sound.
But wire/graphite inductance?????
Only "improvement" I can imagine is through Faith.
Your last post argued that "Something long and thin like those home-made graphite resistors cannot have a low inductance". The point was demonstrably wrong; you then muddy the waters by talking about bits of wire. The review I cited was of a range of resistors commonly used in X-overs - bits of wire didn't come into it.
(Invariably, when you're shown to be wrong, you resort to suggesting that others - who mostly have the advantage on you of having heard the device or devices under review - of liking a bit of distortion. See e.g. prior discussions in this forum about LDR volume controls.)
The point has already been covered and an alternative offered.
See what I mean?
Seems they're seen as a good choice by guitar amp designers on account of low L & C values and good mechanical integrity. On the recommendation of an EE, I used them in R-C filters to suppress transformer ringing where, he suggested, their low L would certainly do no harm.
But, again, this is all off topic. Dueland graphite resistors are niche products explicitly aimed at speaker X-over circuits, nothing else. The relatively low inductance and positive TC (some types only) might be beneficial, they might not be - I don't know and have my doubts - but it is hard to dismiss reports of their contribution to good sound if you haven't heard them yourself or, as that Danish chap did, evaluate them in an untypical set-up.
Your loss, not mine and a tired, lazy argument to boot, however much faith you have in it.
May I respectfully suggest folk stop waffling about products they don't know and revert to good choices for I/V resistors. We can agree that Dueland X-Over resistors don't make the list.
D
My point was factually correct. For any component to have genuinely low inductance it is a firm requirement that the two connections to it are close in spatial terms, not opposite ends of a long rod.Ryelands said:
It is a fact that LDR volume controls add a little distortion, almost certainly more than any other reasonable type of volume control. At least one of the sellers admits this, although he says (and he may well be right) that it is sufficiently small not to be a problem. When the main characteristic of a device is a minor problem, then it is not unreasonable to suppose that people who prefer it may do so because of that problem; it has been known for decades that many people prefer a little low order distortion and some frequency response errors.
Low L is irrelevant to guitar amps, as ordinary metal film resistors have low enough inductance for most purposes up to VHF frequencies. Low C is probably untrue, and in any case irrelevant. Mechanical integrity I would expect to be worse than more modern types. No, CC is used in guitar amps mainly for historical reasons, and partly because they may add a little distortion (which some designers admit).
A CC may be useful to prevent transformer ringing at VHF and above - what sort of transformer was it - certainly not an ordinary audio or mains transformer as that would ring at a much lower frequency where CC has no advantage. I note your EE friend said 'no harm'; he didn't say 'advantage'.
"Good sound" is largely a matter of taste. I don't recall making any comment about use of CC resistors in a speaker crossover. This thread is about I/V.
At best, your point was abstract to a fault - you don't even say what you mean by a "genuinely" low inductance. The measurements I cited show that all bar one of the power resistors assessed (all typical of X-Overs) had a higher inductance than the Dueland.
We don't know the distance between their connections but I'd hazard that the WWs at least are comparable to the Dueland, esp as the latter is straight, not coiled. (Not even the bifilar-wound Mundorf Supreme WWs measured lower.) In this context, the Dueland can reasonably be described as low inductance. How much that matters is of course a another debate but it is misleading to claim otherwise.
As I pointed out at the time, no-one has a clue whether the barely measureable distortion of LDR volume controls is even perceptible let alone critical. Many LDR makers claim that the absence of mechanical contacts is key and that minute differences in spec are irrelevant.
It's a reasonable conjecture but that's all. It is a non sequitur to claim as fact that that is why some people like the device.
Do you have you a source for that? (You didn't last time I asked.) If you can't see the logical gap between your two premises ("LDRs add a little distortion" and "some people like lower order distortion and FR errors") and your conclusion, I doubt I can help you. You don't e.g. know the distortion by type of the devices in circuit or whether some, let alone all, LDR users are among those who apparently like some distortion. And so on.
You're coy on figures. My understanding FWIW is that transformer-related tuned circuits typically resonate at up to 750KHz and that diode switching noise can go rather higher. All of which readily passes back into the mains. My experience is that paying attention to the issue is beneficial.
My comments on guitar amps were (obviously) anecdotal so I'll eschew adding to them.
D
Hm. I would call it a strongly unfounded statement.
You meant GROSS measurable distortion?
Tortuga Audio LDR3 Volume Control: Measurements & Review
No, I didn't mean gross distortion. I read that review a while back - it's not even clear whether the DUT was supplied by the maker. I'm not disputing the reported results but I rather suspect it wasn't.
The author concludes by saying "I considered not publishing these results as I generally avoid speaking negatively about my competitors". Hmmmmmm. Though I haven't used LDRs in years, I didn't consider the Tortuga when I did on grounds of price, complexity and questionable design but, all that said, the result is so obviously an outlier that any responsible reviewer, let alone a competitor, would have contacted the maker to ensure there was nothing amiss with the kit. I see no suggestion that Neurochrome did that.
Still, as we're being constantly reminded, folk tend to believe what they want to believe.
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