Sorry If I read it backwards... ! There is a big difference between a normal SMD basic layout and power based layouts, I am talking of up to 12 layer designs with thermally efficient dielectric (or FR4) thermal vias, bottom terminated devices, SMD power resistors with thermal pads and vias, heatsinking to the case, many layers of copper to act as heat spreaders etc.
As component sizes have decreased over the years and board complexity increased the thermal concentration has also increased requiring more and more thermal engineering... A Flir is a necessity these days on some designs.
Also the use of heavier copper is more common place these days with 4/6oz design being quite common and going higher in some cases, again a 6 layer 6 oz board is quite an interesting beast. Heat spreaders, Berquest pads and phase change solutions are all there to be used...
Using these at the moment a good example of a thermally efficient package,
http://www.farnell.com/datasheets/1915655.pdf
anymore discussions on thermally efficient PCB components would be better in a new thread, especially where ICs are involved.... (look at some ICs and the pin order is mirrored when mounted in lead frame packages compared to the no pin packages (QFNs etc.)
Having deleted a post, AndrewT an SMD resistor is in intimate thermal contact with the PCB, the heat does not have to travel down a long lead wire, same with the bottom terminated packages where a die is used, the die is mounted thermally to an interposter that forms the thermal pad for the device (so no air gap, your comment was rather global without looking more in depths at what component manufacturers are using for packaging), and anyway the distance from the PCB is not that great for SMD devices, putting copper underneath a will aid in removing heat, but most of the components you describe are used in low power designs...
Max its not a new job, I work for a bureau and spend a lot of my year on site doing the fun jobs....
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(something mythological and genuinely feared by the type of audiophile that sticks Bybees up the nostrils and yells catch me if you can)
Marce,
From your posts I have always considered you a first tier PC designer. However now I have to disagree a bit. Surface mount resistors are usually on a ceramic base and those ceramics are actually good conductors of heat. So it is not just proximity and thickness that contribute to that silly difference.
From your posts I have always considered you a first tier PC designer. However now I have to disagree a bit. Surface mount resistors are usually on a ceramic base and those ceramics are actually good conductors of heat. So it is not just proximity and thickness that contribute to that silly difference.
Whatever Simon, there are power devices and normal devices, there is already far to much generalisation on these threads and often not enough detail. What silly difference?
Also where have I said that SMD resistors aren't mounted on a ceramic base?
As to my PCB design abilities the customers that I work for are happy and the designs we work on all seem to work (and I have to keep going back so I must do something right), I'll admit there is very little Audio (some communications a few years ago) mostly instrumentation... with demanding thermal requirements worse than commercial gear... Automotive being one of the more demanding areas, because as well as heat you have often exposure to water and dirt and less budget than class 3 designs. Sorry I can only speak about what I see and work on, if it doesn't meet your exacting standards so be it.....
Also where have I said that SMD resistors aren't mounted on a ceramic base?
As to my PCB design abilities the customers that I work for are happy and the designs we work on all seem to work (and I have to keep going back so I must do something right), I'll admit there is very little Audio (some communications a few years ago) mostly instrumentation... with demanding thermal requirements worse than commercial gear... Automotive being one of the more demanding areas, because as well as heat you have often exposure to water and dirt and less budget than class 3 designs. Sorry I can only speak about what I see and work on, if it doesn't meet your exacting standards so be it.....
As Cowan said there is often a lot of confusion about the various memory models; he published a nice article which explains the concepts:
Nelson Cowan; What are the differences between long-term, short-term, and
working memory?
What are the differences between long-term, short-term, and working memory?
We are talking about complex stimuli (aka music) and as humans have a long term memory storage, the question remains when a difference between two sound events has to be considered as being too small to be stored in the long term memory.
For a reference, heat conduction of a ceramic case opamp is 2.5 times better than a PEM version.
(interestingly, ceramic to air is worse than plastic to air. The through-hole resistors I use are epoxy coated)
A very large proportion the people who have never actually put such things to a good reliable test say things like that.
Shall we say that a great many are enlightened when the rubber hits the road as it were.
I've personally seen it happen dozens of times, including to me.
The article provided seems to be free of actual quantative numbers for the various kinds of memory being discussed. Therefore it may be interesting, but does not seem to shed much light on a discussion where actual numbers are mentioned.
Certain individuals may have questions remaining about when a difference between two sound events has to be considered as being too small to be stored in the long term memory but that could relate to their inability to find out about or create and execute relevant experiments where these things come clearly to light.
In my case the problem walked into the room and whacked me across the face repeatedly until in my usual high levels of stupidity and ignorance, I recognized it. I provided a short summary of real-world experimental results gathered over decades.
This issue can be greatly clarified by actually doing DBTs with variable switchover times, because of their dependency on actually hearing something, and their ability to dispose of imaginary happenings and wish fulfillment makes it so.
Max, I appreciate your input on Bybees. I don't have much else to offer at this time on them. The important thing is that we can express our opinion without being unduly affected by our critics.
Thanks John.
Such 'critics' just make me laugh, especially the one who states "A very large proportion the people who have never actually put such things to a good reliable test say things like that." just after I said three people feel the difference whilst standing on stage.
Cleaning RF ingress is one function of my filter, but the effects go deeper than just that.
In this case of bass rig, the effect is so pronounced that there is no mistake....bass sounded like it was tuned an octave lower, and the apparent power seemingly doubled.
My ears are not so young, but the longer I use them the more I trust my ears.....I also trust my sense of motion/vibration.
Excess noise in resistors is one elephant in the room imo.
Anybody have information regarding excess noise spectrum/level in resistors vs series current vs temp vs freq etc and dynamic characteristics ?.
Dan.
Indeed that can be an issue. In the eighties I got to repair an old VOX AC-30 which was quite noisy. I replaced all these miserable carbon resistors working as anode resistors by some metal film, and the difference was stunning.
In that case the carbon resistors produce a noise modulation that increasses with DC-voltage drop, just the same way than these old time carbon microphenes did.
No myth with that.
This was the one and only time I experienced sound degraded by resistors.
Btw the carbon powder resistors made by Vitrohm in the sixties were "famous" for their modulation noise
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John, you say Bybees improve video, how... you cant put one in line with any Video signal I can think of without problems with the impedance! So how can they improve the video?
There are many ways of filtering that don't employ magic components... In fact I have just completed a second PSU board and not a Bybee in sight, plenty of standard filtering CM chokes, Pi filters etc but not one Bybee I cant understand why?
There are many ways of filtering that don't employ magic components... In fact I have just completed a second PSU board and not a Bybee in sight, plenty of standard filtering CM chokes, Pi filters etc but not one Bybee I cant understand why?
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I find carbon-composition-resistor satisfactory sonorously, they can get the music to stick together in a very natural way.
However, the noise and lack the final solution . with respect to the top resistors.
But we will agree so far that there is a clear audible difference on carbon-based resistors and metalfilm based resistors.
And we are so far, the reason can we fight over, noise is a cause but not the whole, in my opinion
But there is also in sound difference between individual carbon resistors, which is is between the metal film resistors.
Graphite resistors combine in many ways which the two types strength in my opinion.
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There are clear MEASURABLE differences between them. no one will argue that certain carbon resistors are awful.
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