Didnt know where to put this, but I have ordered resistors from different vendors for my diy amp. I noticed that some resistors are about half the size of others, but they have the same values (R, W, %).
They are the same type. Axial. Film.
Are they interchangeable? Whatever fits?
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They are the same type. Axial. Film.
Are they interchangeable? Whatever fits?
Sent fra min EVA-L09 via Tapatalk
Quite likely the spec on the max voltage, voltage dependency and/or temperature coefficients differ.
For the most part they should be interchangeable though it can make a difference in some situations. In an audio amp the feedback resistor connecting the output to the input stage is critical and should be of high quality. (The voltage across the resistor causes it heat up changing the resistance.)
Cheers Dan
There are newer series of resistors that have high power ratings in smaller packages. They have to run hotter as a result. In many situations it won't matter, but I tend to stick with the tried and true, and then derate that. +1 on feedback networks. Whatever imperfections your feedback divider has, those will get impressed on the amp. Not only the series resistor, but the resistor (and cap, if present) to ground.
As I think NP has mentioned, the NFB network is best made up of several identical series resistors,
each equal to the value of the R to ground. This gives the least thermally induced distortion, since all
behave the same and drop identical voltages. That is, if you use a 10k feedback, and a 1k to ground,
then the 10k should be made of ten series 1k resistors. All eleven resistors should be identical,
and all should have the same power rating. The unity gain capacitor is a real can of worms, though.
It's best to avoid that and use a servo instead.
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I ordered just by looking at the w, r, % specs. Don't know about the other parameters, but I guess they can't possibly measure the same in all situations.
What i'm wondering is if it matters. If so, are there any other spec than w, r, % that should be taken a look at?
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What i'm wondering is if it matters. If so, are there any other spec than w, r, % that should be taken a look at?
Sent fra min EVA-L09 via Tapatalk
It really is dependent on exactly how the resistor is used.
In some places it wont matter but in other places it can be critical.
The temperature coefficient as has already been mentioned. If in doubt use the larger resistors
10k, 0.25w, 1%
TE Connectivity: 100ppm/c co-efficient
Multicomp: 50ppm/c
Multicomp handles 250v. TE C 200v.
This is an example. Multicomp is the regular size resistor.
So the smaller one changes twice as much each degree up, if I understand correctly.
How low do we "generally" want them , in amps?
TE Connectivity: 100ppm/c co-efficient
Multicomp: 50ppm/c
Multicomp handles 250v. TE C 200v.
This is an example. Multicomp is the regular size resistor.
So the smaller one changes twice as much each degree up, if I understand correctly.
How low do we "generally" want them , in amps?
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