Camilo_Harper
1 post
Feb 14, 2015
10:05 AM
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Hi guys,
I used to have an account in this forum with almost the same nick "CamiloHarper", but I lost my password and I couldn't get it back.
I write to you because I need your help. I bought from Ebay an impedance matching transformer, for connecting my low-z microphone into my Zoom G3 amp modeler, and to guitar amps, but when I connect the 1/4 guitar male jack that I normally use into the adapter (and then to the amp), I get a really low output volume. It's so low that the sound it's almost inaudible. When I connect my mic without the transformer it works just fine.
This is the adapter I bought
Link
So I dont' know if the problem is that I bought the wrong impedance transformer, or if it's broken and I should change it.
I Already tested the transformer in my Zoom g3, and in a Vox Mini 3 amp, and I have the same problem in both cases.
Could you please lend me a hand?
Thank you guys!
Last Edited by Camilo_Harper on Feb 14, 2015 10:09 AM
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Harpaholic
616 posts
Feb 14, 2015
10:41 AM
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I'm not familiar with that transformer. Which end is labeled Hi Z? The 1/4" male? Is one end of the transformer XLR?
Does your low Z mic has an XLR?
Sounds like you reducing the ohms even lower by having the transformer in the wrong direction?
Last Edited by Harpaholic on Feb 14, 2015 10:42 AM
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Camilo_Harper
2 posts
Feb 14, 2015
10:57 AM
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Hi Harpaholic,
The cable I use is an XLR to 1/4" in order to connect my mic to my amp, like this one.
The problem with this configuration is that even if it works, It doesn't drive the amp hard enough with my low Z mic, so that's why I decided to buy an impedance converter.
So I plug my 1/4" male jack from my mic into the 1/4" female input of the adapter, and then the adapter to my amp, but it's not working as it should.
Looking at the ebay publication it says
Outputs 50000 Ohm 6.35 mm jack plug
Inputs 500 Ohm 6.35 mm jack socket
So, the output should be Hi-z if I'm not wrong?
I'm quite puzzled.
Thanks
Last Edited by Camilo_Harper on Feb 14, 2015 11:01 AM
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MindTheGap
529 posts
Feb 14, 2015
11:15 AM
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Looks like it takes a balanced-signal TRS jack on the input (TRS=3 Pole, Tip Ring Sleeve), so your XLR to mono jack won't work with this.
http://www.audiospares.com/product.php?productid=1709&cat=578&page=1
The normal route is a conventional XLR-XLR mic cable and a transformer that takes XLR input. Or you can get an mic cable that is XLR (female) to 1/4" TRS jack I think.
EDIT: I say 'won't work', maybe there is some wiring of XLR to 1/4" mono that would work, but that's hypothetical.
Last Edited by MindTheGap on Feb 14, 2015 11:21 AM
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Harpaholic
618 posts
Feb 14, 2015
11:54 AM
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A balanced XLR to 1/4" TRS cable should solve your problem if your mic is wired using three pins.
Greg is the expert here, eventually he will chime in and set us all straight.
Last Edited by Harpaholic on Feb 14, 2015 11:56 AM
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MindTheGap
530 posts
Feb 14, 2015
12:19 PM
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The only remaining question is whether the mic is has a balanced three-pin output or an unbalanced two-pin output. As I'm sure Greg will say, and yes of course he is the expert, you can use XLR and jack connectors for all kinds of wiring, balanced and unbalanced, but you might expect an XLR output from a low-Z mic to use all three pins.
What is the mic?
Last Edited by MindTheGap on Feb 14, 2015 12:23 PM
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Camilo_Harper
3 posts
Feb 14, 2015
1:20 PM
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Thanks guys for you help.
I don't have the mic with me right now, but I'm almost sure it has 3 pins. It's a normal XLR connector.
The mic It's a shure bg 1.1 a cheap shure mic but I'm thinking in buying a better one shortly.
Last Edited by Camilo_Harper on Feb 14, 2015 1:24 PM
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Greg Heumann
2945 posts
Feb 14, 2015
8:54 PM
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The impedance matching transformer led you down the wrong path by having 1/4" input and output. TRS ("Tip-Ring-Sleeve") or "stereo" 1/4" jacks have to be used as Mindthegap said in order to carry a "balanced" low impedance signal. The problem is your XLR to 1/4" cable is UNBALANCED. It really isn't the impedance mismatch that is causing the most signal loss - it is that unbalanced wiring has no connection to either pin 2 or pin 3, while balanced wiring (which is what your low impedance mic expects) carries the signal on pins 2 and 3, independent of ground/shield. So when you use an unbalanced cable you're only getting half of the mic's signal (relative to ground which sort of "floats" in between + on pin 2 and - on pin 3.)
To properly connect a low impedance mic to a high impedance input use a BALANCED XLR to XLR cable - this is THE standard vocal mic cable all over the world. Then, between the cable and the high impedance input (amp or pedal) you insert an impedance matching transformer that is Balanced XLR at the cable end and 1/4" mono (unbalanced) at the other. They look like this:
I sell these for $19
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***************************************************
/Greg
BlowsMeAway Productions
See my Customer Mics album on Facebook
Bluestate on iTunes
Last Edited by Greg Heumann on Feb 14, 2015 8:59 PM
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Camilo_Harper
4 posts
Feb 15, 2015
1:14 AM
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Thanks a lot Greg, mystery solved. I will see if I can change the adapter and buy a new cable. If not I will get back to you.
Have a great Sunday.
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