200ohm mic into 600ohm primary?

[Alexandru marian]

My recording setup is:  200 and 600ohm microphones,  1:7  (200:10k) input transformer hooked to a tube preamp (GYraf g9, 1M grid leak)

Testing with a 1:2  (600:2400)  input trafo, I have the feeling the 600ohm mic has a nicer fuller tone.  Of course 1:2 doesn't have sufficient gain so I am thinking about getting a higher ratio 600 ohm primary. 

I know these impedances are relative and what matters first is the ratio, but I also got the impression producers mention impedance ratios based on inductances, with chunkier units better suited for higher imp?

Question is, if I fit the pre with say a 1:4 or 1:8  600ohm transf,  would that present a loading (or any other theoretical) problem for the 200ohm mics?   

Thanks!

 

[emrr]

the source Z relationship is what's important. 

lower Z into higher is usually fine, but there can be exceptions.  one problem is lower 'free' gain with that case.

higher into lower causes a loss of bandwidth. 

the 200 ohm mics will breathe easier, though depending on the transformer they can cause the transformer to develop smiley face EQ syndrome by extending the bandwidth and possibly making the edges resonate.  It's rarely enough to be a problem. 

Get a split center tap type and put it on a 150/600 switch. 

 

[Alexandru marian]

Thank you very much Doug, I started to think my question is silly beyond any reply...

One thing that made me wonder was a comment by Steve Hogan regarding 50ohm Neumann mics hooked to 150ohm Jensens - supposed to trigger a "HF overshoot" which would probably translate into "more britghness". 
When I tried a pair of KM184 in my G9 I did think they were a bit too cutting on the top, but I kind of doubt it was the 200ohm primary but rather the mic itself. Lots lots of people agree the 184 are too bright. But I digress. 

In the past days I managed to do a fairly extensive test with the following gear and a classical guitar:

DPA 4011  200ohm  and  G7  600ohm mics. 

Lundahl 1530    1:7  200:10k 
Lundahl  1530  1:3.5    800:10k
Sowter 9063    1:4      600:10k    (a lot more core/inductance than the L)

With both mics,  the 1:7 ratio made a rich, ethereal tone.  At the same time it can be called a bit stuffed, slightly lacking in focus.  This is particularly evident with the  tube mic, 600 to 200ohms.  Compared to the lower ratios, it seems like the source is further away in the room.    I guess this might be a big part of what is usually called "transformer color". 

With both the low ratio options, both mics, the tone is clearer. I wouldn't say brighter, just clearer.  Not so much of that boosted room sound.    The Sowter has the more robust or direct approach, the Lundahl more velvety and darker. 

Tested with a 2000ohm soundcard outputand RMAA, I can't see any issues in the audio range.  The Sowter is flatter with a tiny bit less distorsion while the Lundahl 1:3.5 has a very slight hf rise/ring which is noted in the sheet, I didn't put the recommended zobel.