Tascam PortaOne...and XLR inputs?

[ecc83]

Your cable has a "balanced" 1/4" plug layout. The PortaOne doesn't need that. You just need an XLR to 1/4" TS plug. Pin 2 of the XLR to the tip of the 1/4" jack. You could tie the sleeve and ring together in the jack if you're handy with a soldering iron, just remember that you've altered the cable as it won't work if you ever try to use it in a balanced application.

The impedance matching transformer shouldn't be needed, although I don't think it will hurt anything. The impedance of the PortaOne is 10K ohms which about what most hi impedance mics are.

You are probably not as ancient as me Rich! The high Z mics of yesteryear were invariable specc'ed as 50k" . High z Reslos and Grampian DP4s were stock in trade for Bingo callers into 'gram' inputs on valve amplifiers.
Of course! Specifications were even more of a mess than those today so what the ACTUAL source impedance of the mics were is anybody's guess!

I strongly suggest the OP gets a transformer, it is not so much an 'impedance changer' as a level lifter giving between 10 and nearly 20dB of 'free gain' depending on ratio and loading. They can also be useful in combating Radio Frequency Interference.

Dave.

 

[TalismanRich]

Thanks Dave. It's been so long since I used any hi imp mics that I had to look up a couple just to see where they are. The Shure 545SD specs at 10K for the hi Imp side, which would a 1-1 match. I couldn't find the spec anywhere for the imp matching transformer.

I would be concerned about putting a 50K mic into a 10K input. You generally want the source to be lower than the input, at least as I was taught.

I still think a SM57 would be ok into the PortaOne. And for $20, the tranny is cheap enough to not be a big issue.

 

[ecc83]

Thanks Dave. It's been so long since I used any hi imp mics that I had to look up a couple just to see where they are. The Shure 545SD specs at 10K for the hi Imp side, which would a 1-1 match. I couldn't find the spec anywhere for the imp matching transformer.

I would be concerned about putting a 50K mic into a 10K input. You generally want the source to be lower than the input, at least as I was taught.

I still think a SM57 would be ok into the PortaOne. And for $20, the tranny is cheap enough to not be a big issue.

I would not fuss very much about "Z outs and ins" in this situation. The source impedance of the venerable SM57 can be found said to be 150 Ohms or 300 Ohms! Loading a nominal 50k traff with 10k will of course reduce level and bork the response a bit but of course, 'transformers do not HAVE an impedance, just depends on the external values.

As you say, the traff is cheap so no harm in having a do.

Dave.