Oxharp
528 posts
Mar 08, 2013
11:10 AM
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Hi all you guys in the know.
Could you tell me in easy understanable terms why a crystal mic needs a 1Meg volume control or Amp Line in?
I have just ordered a BluXLab Crystal mic an VC and was curious.
I have some crystal elements and they all sound weak through my Amps. Am I missing a trick here?
Cheers
Russ
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Oxharp
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SuperBee
995 posts
Mar 08, 2013
3:28 PM
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My crystal also sounds weak. I assumed that's because it is weak. Now I'm wondering. What's the best/easiest way to measure input impedance?
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1847
590 posts
Mar 08, 2013
9:33 PM
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What's the best/easiest way to measure input impedance?
forget input impotence
just tell her.. i promise you won't feel a thing
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tipjar
Last Edited by 1847 on Mar 08, 2013 10:42 PM
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SuperBee
997 posts
Mar 08, 2013
10:19 PM
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Yeah I dunno 1847, it feels kinda like a joke, but there seems to be some element missing...
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SuperBee
1000 posts
Mar 08, 2013
11:02 PM
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A bit like my element. Sounds like a crystal mic only weaker.
I really wanted my 1000th post to be stronger too. Ah well! I'm glad it's over...
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STME58
376 posts
Mar 08, 2013
11:58 PM
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I saw an Audix impedance matching cable listed on the Guitar Center website. Is this likely to improve the performance of a crystal mike into a tube guitar amp?
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Kingley
2386 posts
Mar 09, 2013
1:26 AM
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STME58 - No an impedance matching cable won't do the job with a crystal mic.
SuperBee & Oxharp - Crystal elements ideally need to see a minimum of 1 meg to perform well. They seem to perform even better if they see a 5 meg input. One way of achieving this is to build a Jayphat box. A quick google search will bring up the schematics of it. Another way, which is probably better is to have the input on your amp changed to 5 meg. I think it's simply a matter of adding/changing some reisitors. Mark Burness or Greg Heumann can probably explain how to do that correctly. Ideally if your amp has two or more inputs, then you could make one suitable for crystal mics and the other(s) suitable for CR/CM/Dynamic mics. Sonny Jr often did this on his amps.
The only other thing to be aware of is that crystal elements die over time and are very susceptible to changes in temperature or being dropped. They are very fragile and will easily break. They will also change their tone over the course of a gig as your cupping warms up the element and affect the moisture levels present in the air. A good crystal is a thing of beauty to play and cannot be beaten in my opinion. However due to the fragility of them, if reliability is needed then I'd suggest sticking to CR/CM/Dynamic elements.
Last Edited by Kingley on Mar 09, 2013 1:30 AM
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5F6H
1575 posts
Mar 09, 2013
4:29 AM
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@Superbee - "My crystal also sounds weak. I assumed that's because it is weak. Now I'm wondering. What's the best/easiest way to measure input impedance?"
I strongly recommend that you DO NOT try and measure the impedance of the element with an ohmmeter, because the ohmmeter does this by applying a voltage to the element and I have heard from many sources that this is dangerous to the element...besides, the old Astatic & Brush elements won't give you a meaningful reading in ohms anyway, they used to express impedances as "equivalent to a 390pf capacitor", or something like that. Actual DCR of the element is likely to be massive.
You could clip a 1-5Meg resistor accross your mic cord jack plug, blow through the element & try and read an AC voltage with a true RMS meter, I'd do a few good bent 2 draws & 3 blows & see if you can determine an average?
The Kobitone elements do list impedances, but these are relativey low (still hi-z) at a few thousand ohms.
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STME58
379 posts
Mar 09, 2013
9:43 AM
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@Kingley, Thanks for you response on the cable, you saved me from wasting $25.
I found what looks to be a commercially manufactures Jayphat box at Musicians friend, the Lehle Sunday Driver. It uses a 9v battery has switchable input impedance between 1Mohm and 4Mohm. Has anyone tried one of these with a crystal mike?
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