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Dirty-South Blues Harp forum: wail on! >
OK to measure resistance to find "hot" CR/CM?
OK to measure resistance to find "hot" CR/CM?
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Hakan
243 posts
Aug 29, 2012
1:47 PM
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Is it possible to measure resistance to identify "hot" CR/CM elements without listening to it? Is high resistance even an important factor to decide that?
I have heard different opinions. And I didn't find any information in Forum Search.
http://greenbulletmics.com says:
Another thing that I've heard people say is that the higher the resistance reading is, the more gain, or hotter the element will be. This is nonsense! Differences in resistance of the windings is not going to determine how hot an element will be. At least not at differences as small as 100 or so ohms on a high Z controlled magnetic element as used in today’s applications. Yes, a low Z CM element will not have the gain of a high Z element, but the difference in resistance is much larger, and they're usually plugging them into a guitar amp that has 1 meg or higher input impedance. While it is true with certain microphones, a small difference in resistance with CR and CM elements is not going to make an element stronger or weaker than another. I have had CR's close to 1,400 ohms that weren't any stronger than CM's that were 1050 ohms. In fact, I've had some lower resistance elements that were much hotter than elements of higher resistances. There are many things that determine how much gain these elements have. Slight differences in resistance is not one of them.
There are many things that can affect how well an element of this type performs. I can't get into everything, but the main ones are magnet strength, armature alignment, diaphragm condition, debris getting into the magnetic assembly, crud collecting on the diaphram and corrosion build up.
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Håkan
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5F6H
1327 posts
Aug 29, 2012
2:19 PM
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Dave Kott's word is good enough for me. It's true, you cannot determine what the element will sound like based purely on a dc resistance reading. For a given number of turns, this might tell you how relatively thick/thin the wire used in the winding is, but that is all. Impedance is an AC concept, the resistance that you measure is dc - the element is primarily concerned with the AC.
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Greg Heumann
1763 posts
Aug 30, 2012
12:15 PM
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I will second that - in my experience the coil resistance tells you ONLY that the coil is electrically intact from terminal to terminal - i.e., 0 ohms would indicate a short, and no reading would indicate an open - either of which would mean the element is non-functional. But whether that particular element is hot or not? No correlation with resistance.
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/Greg
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Hakan
244 posts
Aug 30, 2012
6:38 PM
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Thank you both for clarifying!
Håkan
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