Preamp input impedance.

  • Thread starter Thread starter Steenamaroo
  • Start date Start date
Dang, I wouldn't have expected something that small to be so expensive to post. I just sent some small circuit boards to France and Finland, and it was about US$5 in postage. But I also sent a MXL V69 to Germany and that was steep. (US$79 or so)

I know. I found it hard to believe myself! :(
Ah well, maybe I'll find something over here. No rush.

Thanks for the link kip but I'm afraid that's not the right kind of thing. Cheers anyway though. :)
 
Hey msh, i found a good deal on a pair of Jensens (JE-642-90) which are 1:25.

One of these'd be alright as a complete replacement right?

The lundahls are 1:37 but if I understand this right, the fact that my pres are 750ohm input impedance (seems lower than most) makes the jensens more suitable doesn't it?

They are described as being "suitable for 50ohm ribbon mics" but that throws me cos it sounds like you'd use it inline without modding the mic.
 
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I can't find the spec on that unit on the Jensen site, so I can't say. It would need to have very low primary DCR.
 
The seller has a handwritten drawing of the transformer that is marked 550 ohm and 2 ohm.
Obviously I don't know how reliable this is, but what would that mean for my application?
Thanks.
 
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Hard to say, that could be the nominal impedance or it could be the DCR. Those figures are not acceptable for DCR, but they could be fine for nominal impedance. The ratio is pretty low though, 1:16. Not enough really, I think maybe the "suitable" comment meant that it would yield a 50 ohm output in a ribbon mic, which is not a very useful concept anymore.
 
Oh wow. I really don't understand this,lol.
Might be safer to just hold off and get a 'tried and tested' lundahl or something.

Thanks again for the help.
 
Well, the little reslo arrived today, and WOW aren't they just little.

I thought I'd literally bought an ornament by mistake for a minute.

Anyway, fired it up and checked it out and I have to say I'm very very impressed from the get go.
OK, so i have the gain at max which I just can't do with any other microphone, but my pres are pretty nice and they seem to be letting me off with it.
Noise is obviously a problem, but not as much as I expected.

I've ordered a transformer from Xaudia Uk and honestly, if that improves this little mic in anyway I can't wait to hear how.

It seems to have stacks of bass, just suits my voice a treat.

Anyway, A/B to come when the transformer arrives.
 
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My transformer arrived today from xaudia.
Got it fitted and checked it out. Sure enough it did what it was meant to do. The output signal is much hotter which is great, and noise is much less audible. Win! :)

That said, the tone of the mic has changed completely. I expected (from reading about other transformer upgrades) that the mic may sound a little clearer or more detailed, but instead it's incredibly deep and bassy, to the point where I'm definitely going to need to eq a lot out in most scenarios.

I haven't used it enough to say if this is a good change or a bad one, but I definitely wasn't expecting it.
That little mic was bassy enough to start with.
 
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