Page 1 of 1
Beyer m55 and general impedance query
Posted: Wed Jun 27, 2018 7:00 pm
by pond_Archive
Hi everyone,Apologies if this has been asked, I have been searching for an answer but it might be that I don't even have the required knowledge to search for it effectively...Long story short, I am considering buying a Beyer M55-HN. It is a vintage dynamic omnidirectional mic originally designed for amateur tape recording. It is a dual impedance mic. It can be wired for either 200ohms or 80kohms.It terminates with a 3 pin tuchel connector, which I would want to convert to XLR. The thing that concerns me however, is this information from its data sheet regarding sensitivity:At 200 ohms, output = 0.12mV / -78dBAt 80k ohms, output = 2mV / -54dBMy preamp inputs are rated 2.8kohms, and I would prefer not to use DI boxes for these m55s. So i figure I need to use the low-z output, but then that sensitivity seems super super low from what I can tell.Anyone have any advice or clarification they can offer me?One possibly stupid question I have also: What happens if I wire the both the high and low impedance outputs to a single pin? what impedance would that equal??thanks
Beyer m55 and general impedance query
Posted: Thu Jun 28, 2018 7:00 pm
by bassdriver_Archive
I would go with the 200 ohms output. this will match with your preamp input (5 to 10 times lower than the input impedance). I guess the 80k output was used for some old taperecorders.a quick search on german forums showed this:XLR pin 1 ground 2 yellow 3 transparenthope that helps.
Beyer m55 and general impedance query
Posted: Thu Jun 28, 2018 7:00 pm
by pond_Archive
On reading back over that, I realise I should probably make the question that I'm asking clearer.Basically, what approach should I use to get the best possible signal to noise ratio in this situation?
Beyer m55 and general impedance query
Posted: Thu Jun 28, 2018 7:00 pm
by pond_Archive
And would I be correct in thinking that at 200ohms thermal noise would be approx -130dB, giving this microphone a SNR of 52dB when wired correctly?
Beyer m55 and general impedance query
Posted: Thu Jun 28, 2018 7:00 pm
by pond_Archive
Thanks for replying. I've just returned to apologize actually, I missed a small but crucial detail... The output ratings are referenced to 0dB = 1V/microbar, which seems to be an older standard.This, I believe, gives the microphone a much more usable output of 1.2mV / Pa or -58dB.Sorry for wasting everyones time.