Killa_Hertz
1387 posts
May 16, 2016
4:42 AM
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Idk, but. ...Im interested to find out.
If you don't mind me asking, how much was Said VC?
Im thinking it may be a good idea to try and build one with a switchable Hiz Xfmr.
Hmm.
Also what mic do you have that's hiz with a screw on? 585?
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dougharps
1229 posts
May 16, 2016
6:16 AM
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Transformers themselves are reversible. If you used it backwards you could theoretically use your hi-z mic into a low-z PA. I have transformers w/o volume that work in either direction.
If the volume control is built into the same assembly I don't think it would hurt the volume control except possible if phantom power is on, but I can't say for sure. Better email Greg.
Edit:
So far as using it to make a hi-z mic into a higher-z, you could end up with an impedance mismatch between the mic assembly and amp, and lose some of your frequencies or signal, like a crystal mic into a guitar amp.
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Doug S.
Last Edited by dougharps on May 16, 2016 6:19 AM
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dougharps
1230 posts
May 16, 2016
10:05 AM
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The transformer match from high to low or low to high-z, being reversible. They don't automatically adjust to what is needed to match, they either take low to high or high to low, with specific changes to impedance.
Here are the two Shure transformers I have. Note the text about how they work.
Shure line matching female XLR transformer
Shure line matching male XLR transformer
The volume control complicates things a little, which is why contacting Greg is the best way to go. I don't know if phantom power could hurt the volume control, or not.
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Doug S.
Last Edited by dougharps on May 16, 2016 10:08 AM
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Killa_Hertz
1403 posts
May 17, 2016
4:24 AM
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Phantom WILL hurt the transformer.
Im curious to hear gregs weigh in.
Im an Electrician so i get alot of this right off the bat. Just the electronics end (the amp) is the part im unsure of. I dont know much about them specifically.
In my mind it will step up the impedance again, but in not exactly sure.
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Greg Heumann
3232 posts
May 17, 2016
7:49 AM
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I think you want to use the volume control with a high impedance mic.
No it won't work. It will NOT damage anything so you can try it, but it won't work.
First, the high impedance mic won't be wired the same as the low impedance mic. Low impedance mics are wired in "balanced" mode with the signal on XLR pins 2 and 3. High impedance mics are wired in "unbalanced" mode with the signal on pins 1 and 2 (pin 2 hot) or 1 and 3 (pin 3 hot).
Also, a volume control is impedance-specific. One made for high impedance isn't going to work well for low and vice versa. It is ALSO wired differently (balanced vs unbalanced.)
Impedance matching transformers are indeed bi-directional but it is difficult to use them that way because the connector sex is different.
USUALLY an impedance matching transformer is placed at the "far" end of the cable. When we want to connect a low impedance mic to a high impedance input, we need an impedance matching transformer with XLR female to 1/4" male connectors. When we want to connect a high impedance mic to a low impedance input, we need a 1/4" female to XLR male device. The latter is commonly referred to as a "DI" or "Direct Input" box.
Some of the Shure transformers used to come with various adapters so you could change the sex (and then they could use either bathroom.)
Lastly phantom power PROBABLY won't hurt an impedance matching transformer if accidentally applied. Properly designed sources of phantom power have built-in current limiting set to very low current to protect devices that weren't designed for it.
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***************************************************
/Greg
BlowsMeAway Productions
See my Customer Mics album on Facebook
Bluestate on iTunes
Last Edited by Greg Heumann on May 17, 2016 7:50 AM
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Halffast
39 posts
May 17, 2016
9:06 AM
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Kind of on a tangent ; I'm looking for an IMT that takes 1/4 mono female to 1/4 mono male , without using a bunch of adapters . I built a mic from an old telephone handset , lo-Z , earpiece . It has good tone but no "punch" . It is terminated with a 1/4 male mono plug . I just want an IMT between that and my pedal board and can't seem to find one . In some thread on here ( that I can't seem to find now ) I read that somebody had an old Radio-Shack unit that was exactly what I'm looking for , but I don't think they make it now . Any leads ?
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Killa_Hertz
1407 posts
May 17, 2016
9:51 AM
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Good Stuff Greg.
Almost every transformer can be used backwards. Just depends which u use as the primary and which the secondary.
But most small transformers are very touchy when it comes to stray voltage, so that's why i was pretty sure phantom would kill it. Didn't know about the protection / limiting circuit.
I also didn't think about the different wiring on the xlr vs various unbalanced connectors. Have to keep that in mind.
I had a bunch of of topic questions im going to stick in another thread.
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