We understand, Pavel, and I agree that this is important. Thermal capacitance is the key, and, of course, tempco. This is one of the reasons why I specified Holco resistors as feedback resistors, approximately 20 years ago, in the Parasound HCA2200. Thicker leads and larger body than even 1/2W Resistas.
Building a reference divider for surge testing is very challenging. Construction to balance the voltages at high frequencies uses lots of tricks to compensate for errors. Here are some examples of hv versions: High Voltage Divider Making a small one using similar techniques would make sense. The challenge is verifying its performance.
What I am hoping for and getting, is results that show differences. It is all nice to be as accurate as possible, but nit picking about what COULD go wrong, or what makes a PERFECT test, doesn't show results, just the headaches.
For example, once, Dr. Hawksford 'nit picked' Walt Jung, Scott Wurcer and me, because the EQUATIONS showed that a real capacitor's inductance would effect the NULL. What he overlooked is the the AMOUNT of deviation could easily be controlled by proper choice of the test signal settings, and by bandwidth limiting the test signal with a quality polystyrene cap to have just enough rise-time for the signal to show properly on the oscilloscope screen. This removed the problem that SEEMED so apparent in the equations. Had Dr. Hawskford contacted me in advance, or tried the test, himself, this would have become self evident. However, please remember that Dr. Hawksford and I are competitors, as well as colleagues, and a 'justifiable criticism' by him, might make him look like he was really on top of it. Matti Otala did the same thing to me, on occasion, as well. Seems to be a PhD trait. ;-)
For example, once, Dr. Hawksford 'nit picked' Walt Jung, Scott Wurcer and me, because the EQUATIONS showed that a real capacitor's inductance would effect the NULL. What he overlooked is the the AMOUNT of deviation could easily be controlled by proper choice of the test signal settings, and by bandwidth limiting the test signal with a quality polystyrene cap to have just enough rise-time for the signal to show properly on the oscilloscope screen. This removed the problem that SEEMED so apparent in the equations. Had Dr. Hawskford contacted me in advance, or tried the test, himself, this would have become self evident. However, please remember that Dr. Hawksford and I are competitors, as well as colleagues, and a 'justifiable criticism' by him, might make him look like he was really on top of it. Matti Otala did the same thing to me, on occasion, as well. Seems to be a PhD trait. ;-)
I've been following this thread for so long and I currently have no mean of testing a resistor noise down to -170dB considering the equipments I owned are very old and not calibrated to make such accurate tests.
But I am wondering what's noise is more important to look at. i.e those coming from switching of active devices such as transistors or the noise (thermal/ white/pink/eletctro-magnetic induced noise due to the conduction of electricity in the metal) of passive devices such as resistors?
I understand the concept of everything else matters in a good circuit but the practicality of obtaining such low noise resistors that needs to be matched and pre-selected for a DIY community or mass production seems to be of much difficulty.
But I am wondering what's noise is more important to look at. i.e those coming from switching of active devices such as transistors or the noise (thermal/ white/pink/eletctro-magnetic induced noise due to the conduction of electricity in the metal) of passive devices such as resistors?
I understand the concept of everything else matters in a good circuit but the practicality of obtaining such low noise resistors that needs to be matched and pre-selected for a DIY community or mass production seems to be of much difficulty.
Simon, you may have mentioned it once, but what resistors are you using for the REFERENCE resistors in the bridge?
Are these just as good as the Resista, or is it because you series parallel the parts that the residual drops low enough.
Hello Simon
I might of missed the posting of THD data on the Dales but how did they measure.
Also, this may seem like a stupid question but have you measured carbon resistors the cheap Chinese types ( I know they are noisier than metal film types ).
Regards
Arthur
Pheonix, look back a few pages and get the info that Ed Simon has already posted. He has posted the Dales, Vishays, at least one cheap resistor, and many more. It is all here for you to see.
I would like to see tests results for some SMD resistors in 1206 package.
Smaller dimensions should in theory improve the layout and reduce some inductance / capacitance of the signal paths.
I suggested the 1206 because of the power handling
The best to worst Resistas varied by about 6db. These are not as good as the best but always better than the worst.
I believe the difference you refer to is the difference by the measurements you made.
Simon, that makes sense. Nothing is perfect, and nothing similar is EXACTLY the same. I would expect a range of distortion values, but I sure like the fact that they are all pretty darn good.
Just this week, I finished a protoype phono stage using OLD Resistas mostly with a few OLD HOLCO's thrown in. We hope to show it in a German Audio show in May. I trust my Resistas will not fail me.
Just this week, I finished a protoype phono stage using OLD Resistas mostly with a few OLD HOLCO's thrown in. We hope to show it in a German Audio show in May. I trust my Resistas will not fail me.
John which company will that be? (I assume it's the Munich Hi-End show). Maybe I can write up on it.
jd
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