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Resistor question

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#61
SY said:
That link might be the single dumbest thing I've read today, and there's been a lot of competition.
Click to expand...

And what is the moisture resistance of shellac? Why does moisture raise the resistance?

Actually Allen Bradley resistors have the lowest distortion of carbon composition types. Carbon films have lower distortion, however for the same wattage rating they do not tolerate surges as well. (Sort of obvious if you understand the construction and concept of thermal mass.)

In a different thread a while back someone list his carbon composition resistors in order of preference. He was almost perfect in list the highest distortion as best and the Allen Bradley as least favorite.

As to the moisture resistance of shellac, that is why doilies were popular. Shellac used to be the most common finish for fine furniture. If you left a cold glass of water on the surface you would get a white ring. Placing a coaster or doily under it solved the problem. Doilies also kept things from sticking on hot days.

So all we need now is resistor doilies! 🙂
 
#62
Merlinb said:
I'll take that challenge! 😀
StereoTimes - Commentary
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One of those issues that folks often misunderstand is power line loss. The actual loss is supposed to be a maximum of 5% at your homes power panel. As most US homes have 200 amp service this require a source resistance of 5% of 220/200 or .055 ohms. From the service panel to the gear may be another .05 ohms or less. The plug power cord and IEC socket can be as high as .5 ohms but most come in under .1 ohm.

Now a fuse when under stress can hit an ohm or more. So the fuse can contribute to most of the loss in the line power. Now I can actually measure directivity in the conduction of wires. It can be as high as 150 dB down from the signal voltage. I can even imaging that switching the direction of a fuse may change the fit of the connection.

Now it is really possible to make a fuse that will provide less voltage sag under load than a standard fuse. (Of course it may not offer the same protection.)

Now we get to Tesla coil treatment of fuses. Tesla coils actually do have an effect. They can screw up the way your brain functions! (Really!)

Now one of the jokes in pro audio was to set up the gold fuse company as some folks will buy them for ridiculous prices. However these days you can actually buy gold plated fuses.

So although it is possible that fuses could have an effect, I am with SY on this one. The article is humorous. (But I do not doubt the reviewer perceived differences.)

(BTY power cords can make a difference, but the reduction of line loss is not the reason. Some power cords are actually filters and reducing line noise conducted into some gear will have a measurable difference. So spending $10,000 on a power cord can actually improve things. But then why the !!!! would you buy gear that is that sensitive to line noise?)
 
#64
coresta said:
And nobody spoke about microphony in resistors ... a real effect ! Thats the reason why Audio Note mount their circuitry on wood plates , a lot better than epoxy ....
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I did some measurements of the sensitivity of resistors to vibration. Now there is a baseline of vibration in most places of around .005 Gs. My electrical sensitivity is around -125 dB without any fancy techniques, so shaking them at 1 G would let me see the sensitivity well below -160 db.

The results were fairly reasonable, there was no sensitivity.
 
#70
simon7000 said:
Now a fuse when under stress can hit an ohm or more. So the fuse can contribute to most of the loss in the line power.
Click to expand...
Wow, your amp runs straight of the wall voltage? Cool! Mine has a transformer, boo 🙁

Now I can actually measure directivity in the conduction of wires.
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You should be receiving the Nobel prize for physics pretty soon then! 🙂
 
#72
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#73
Half way down the page,

Quote..
Picture below shows a close up of the wooden board holding the RIAA correction circuit showing in detail the 2 E80F input valves, the two watt Audio Note™ tantalum resistors and the serious number of silver foil signal capacitors and the two RIAA correction transformers at the top right.

Link:
Audio Note


I will have to think about this..Thank's for the information.

Regards
M. Gregg
 
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#75
M Gregg said:
Half way down the page,

Quote..
Picture below shows a close up of the wooden board holding the RIAA correction circuit showing in detail the 2 E80F input valves, the two watt Audio Note™ tantalum resistors and the serious number of silver foil signal capacitors and the two RIAA correction transformers at the top right.
...
Click to expand...


Wood and circuitry sounds like disaster, meaning a fire hazard waiting to happen. This looks like a commercial product, I suspect it is just made to look like wood.
 
#78
6speed said:
Wood and circuitry sounds like disaster, meaning a fire hazard waiting to happen. This looks like a commercial product, I suspect it is just made to look like wood.
Click to expand...


That was my thought (Fire risk)...But further down it looks like plywood..

It looks like its coated with a lacquer of some kind.
And yes this is Audio Note M9 preamp..:scratch1:

I have no problem with wooden chassis...Circuit boards???😕

However it has made me think..M77..😀...I would want to mount tag board on the wood and that isn't what I'm seeing here!
Whats the resistance of ebony..😀 And yes it looks like 2W tantalum resistors. Valve bases are lifted with nuts..no pun intended with wood..😀
I wonder what the underside of the wood PCB (connections look like)..

I keep looking for the date 1/4/14 etc..but there isn't one..

Regards
M. Gregg
 

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#80
Densified wood..

www.roechling.uk: Laminated densified wood / compressed wood / Lignostone / Transformerwood

https://www.google.co.uk/search?q=d...JYmAON3hgIAK&ved=0CAgQ_AUoAQ&biw=1455&bih=665

Does that include laminate flooring?

https://www.google.co.uk/search?q=d...55&bih=665#q=densified+wood+flooring&tbm=isch

I guess pick the colour of your circuit board..light oak seems nice..😀
Looks like an M77 dark or light oak for a fun test then...sorry off topic..
Many years ago I have built on all sorts of things Acrylic, Tufnol, even slate..but this is a new one..😀

Regards
M. Gregg
 
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