guitars @lemmy.world Sarsaparilla @aussie.zone 1 yr. ago

Beginner - Amp/Mic Advice Needed

Hi There! I am a beginner to amplifiers and I purchased an Aroma AG-15a for busking, which has separate guitar and mic inputs. I purchased a dynamic stage mic (Behringer BA 85a) and an XLR to 1/4inch stereo TRS cord, but there is no sound when plugged in, even with both volume knobs on the amp turn up to full. I tested the dynamic mic on a different guitar amp (no mic input) and it worked, so the mic is not faulty.

I rigged up a connection to the problem amp with a battery powered Zoom H1N recording mic, and it worked, but this is obviously not the mic I want to use for performing. Everything I read says a dynamic mic is plug and play in this situation. I am finding it impossible to find information anywhere about whether there is something wrong with the amp, if I need a different mic, or I'm doing something else wrong.

So having watched a few videos, I discover that I might need a Mic Impedance Transformer to get 'power'/volume to the dynamic mic. Is a Mic Impedance Transformer a type of Mic Pre-amp?

Should I buy a Mic Impedance Transformer or a Mic Pre-amp??

P.S. I made a connection via a Hum Eliminator, and actually heard the mic thru the amp for the first time, but it is still very soft.

How do I solve my problem?

PLEASE HELP!! I'm tearing my hair out!

Thanks in advance for your expertise in this.

10 comments

Definitely something going on that doesn't make sense here - input impedance of the mic input for that amp appears to be 1k, with the mic at 300ohm. Yes it's mismatched, but not enough to cause zero signal.

I'm guessing cable - can you borrow a standard xlr and try an adaptor, or get another xlrl to 1/4”?
- Thank you for the advice and for pointing out the input impedance of both the mic and mic input on the amp .... I have better understanding of that now. Your guess was correct in that it was the cable ... a standard XLR to TS jack did the trick! 😊
  
  Fantastic news, glad you got it sorted
- Ok so impedance does not seem to be the issue, then. I'm gonna have to buy a xlr-ts mic cable or adapter tomorrow. Strangely, with all my cords and adapters, I don't have THAT one, of course! Plenty of XLRs, just nothing to convert to the TS jack! Hopefully tomorrow, Aroma or the seller can get back to me with some idea, as well.
Not seeing a lot of specs for those products on line but I suspect you may need the preamp, which is not the same as the transformer. Are you certain the mic in is a TRS jack? It seems like the kind of product that may only have a don't see any specifics about the mic preamp on the Aroma amp, which makes me suspicious. How did you hook the zoom recorder to the amp input? Was it a line out? If so and that configuration worked, I'd say that further points toward the preamp.

I might need a Mic Impedance Transformer to get 'power'/volume to the dynamic mic.

Just erase that detail, its wrong one way pr another and windmills do not work that way.
- The mic-in on the amp is a TS jack (most likely), but my cord is a TRS ... shouldn't matter though? Yes, I used the line-out on my Zoom, with a 3.5mm TRS to 6.35mm TRS adapter.
  
  The Aroma website provides little to no info on the amp, but here is a local music store that has some specs. And this is the mic - https://www.behringer.com/product.html?modelCode=P0E7P
  
  Here are the apparent specs of the input jacks on the amp
  
  Channel 1 Input socket: 6.35mm jack Input impedance: 10Kohm EQ: Bass, Treble, Volume
  
  Channel 2 Input socket: 6.35mm jack Input impedance: 1Kohm EQ: Volume, Echo
  
  If the amp is a TS input, it is unbalanced and needs a XLR to TS cable. It does matter going from balanced to unbalanced signal. Double check me on that though with. Multimeter or pinout diagram or something.

You've viewed 10 comments.