Microtech Gefell M582

I was just looking at this circuit diagram of a Microtech Gefell M582.
http://www.microtechgefell.de/dmdocuments/M582_Stromlaufplan.pdf
To my surprise the output transformer is connected between the anode and the cathode, not as one would expect between the anode and ground.
Also the 4700 pF capacitor in parallel with the 4700 ohm cathode resistor surprises me.
Is this a form of frequency response correction?
Just curiuous!

RuudNL said:

IIs this a form of frequency response correction?

Click to expand...

Yes, that's HF boost.

That's what I thought!

The trafos in CMV563 and CMV551 are wired like that too, but without those capasitors(C1, C2). The trafo could go to ground as well, but obviously some feedback was desired.
I have a few of M582:s. I like to use these mics for some purposes.

Also: no grid resistor! 

I would say, that the M582-circuit deserves a bit more attention. These afore mentioned details are a perfect compromise between extending the low end of the frequency-curve and at the same limiting the high end responce to the desired level, but not just that, because at the same time the feedback is supposedly reducing non-linear distortion. How does it affect the primary impedance? Probably lowering it?The circuit of UM57/CMV563 is very similar except the afore mentioned details and in fact when comparing M582/M7 with a UM57 or CMV563/M7, I did not hear any big differencies.  Sorry, just my memory, because it`s been years ago, that I have done any comparing with these mics. M582 has a much smaller trafo than the UM57/CMV563, so how come is it getting so close? I could not find the trafo-ratios for these mics, so I cannot say. I think, that by playing around with C1 and C2 you can adjust a lot, but to be honest, I guess I prefer the mics with bigger trafos nevertheless. I think I need to check those mics again, when I got more time.

RuudNL said:

Also: no grid resistor! 

Click to expand...

As I see it, the tube is cathode biased, so the resistor is not needed for biasing. I also assume, that neither is it needed for a grid leak. My reasoning is that once the mic is on, there is at least theoretically a signal flow uninterrupted, that prevents the grid charging. The feedback from the trafo may also have a role in that.  But maybe there is another better and more correct explanation?
Also if we see the circuit as a poweramp, it makes sense not to have those resistors unless you meant grid stoppers.

What I meant is that the grid is theoretically 'floating' for DC.

If the vacuum in the tube is excellent and the anode current is small, the grid current is very small so the few TOhms of insulators resistance is just enough to keep it at 0V DC, IMO.