Some questions about the Sony C37a - mics with cathode follower

[snigglepit]

A growing list of microphones with only a cathode follower as impedance converter:

If you know of any, please post them.

I believe the AKG C60 was also a cathode follower design?

 

[rock soderstrom]

I believe the AKG C60 was also a cathode follower design?

Noted, thank you!

 

[Tubetec]

 

[wlinart]

A growing list of tube microphones with only a cathode follower as impedance converter:

historic:

Sony C37a, C800
Altec M11 "Coke Bottle"
Altec 165a "Lipstick"
Oktava MKL-2500
AKG C12a, C60, C61
Bruel&Kjaer
RFT MV101

modern:
Royer Labs MA-37
Royer Labs R-122,
Royer Labs SF-24V
Royer SDC mod
Mojave Audio MA-100
Mojave Audio MA-202ST
McHugh AMM-68

​

If you know of any, please post them.

I think it's the r-122V instead of the normal r-122.
Also funny how of the modern mics, 6/7 are designed by David Royer

 

[rock soderstrom]

I think it's the r-122V instead of the normal r-122.
Also funny how of the modern mics, 6/7 are designed by David Royer

Thank you, I have corrected it.
David Royer is the number one evangelist for CF in microphones. I think he has the most experience with it by now, he knows his stuff!

David Royer talks about C37a and his take of it, the MA37.

 

[capacitorless]

Not dissing tubes, but I wondered what the advantages are of a tube cathode follower, versus a fet cathode follower? I mean solely in terms of audio/sound quality.

Setting aside the requirements of providing B+, filament current, heat dissipation and maybe having to select individual tubes for microphonics/noise

 

[k brown]

Not dissing tubes, but I wondered what the advantages are of a tube cathode follower, versus a fet cathode follower? I mean solely in terms of audio/sound quality.

Setting aside the requirements of providing B+, filament current, heat dissipation and maybe having to select individual tubes for microphonics/noise

I have to admit that I stopped building tube mics when I realized I couldn't tell any difference between the CF tube mics and my best FET mics. Since I record only Classical music, I have no need for plate-load tube, or trafo euphonic coloration.

 

[rock soderstrom]

Not dissing tubes, but I wondered what the advantages are of a tube cathode follower, versus a fet cathode follower? I mean solely in terms of audio/sound quality.

I can't tell you that for a cathode follower yet. Ask me again after my experiment With the usual anode out impedance converters, I hear a signature in the sound that FET amps don't have.

Setting aside the requirements of providing B+, filament current, heat dissipation and maybe having to select individual tubes for microphonics/noise

The effort is of course very high for a tube amp compared to the FET version, you can't argue that away. Whether that makes sense or not is something everyone has to decide for themselves.

This is not only true for microphones, but also for micpres, EQs, compressors, etc.

Edit: Please let's not derail this thread into a hot glass vs sand comparison.

 

[Recording Engineer]

I believe the AKG C60 was also a cathode follower design?

Don’t forget the AKG C12A as well.

 

[capacitorless]

I'm looking at an Innertube MagMic/MM2000 & I'll try to figure out whether that's CF vs plate load, just to see if that can be added to the list.

Edit: plate loaded (which makes sense given that it's a character mic & somewhat patterned after a C12)

 

[gyraf]

..and C12VR - "The Turd"..

 

[rock soderstrom]

..and C12VR - "The Turd"..

Thanks capacitor and Jakob! AfAIK AKG C12VR and "The tube" have no cathode follower inside.

 

[Tubetec]

We had a couple of AKG 'the tube' mics in a studio I worked , they didnt get a whole lot of use really , Most prefered either U87/89 or Akg 414 ,or else brought in U47's or U67's .
I dug out the user manual for the B&K CF mics , I'll post the schem and other details later .

 

[rock soderstrom]

We had a couple of AKG 'the tube' mics in a studio I worked , they didnt get a whole lot of use really , Most prefered either U87/89 or Akg 414 ,or else brought in U47's or U67's .

"The tube" and the C12VR have a bad reputation. Probably justified, I also once had a "The tube" in use. It did not leave too positive memories.

I dug out the user manual for the B&K CF mics , I'll post the schem and other details later .

Thank you very much! I still need the info, it is somewhat confusing by the modularity at B&K.

 

[gyraf]

You're off course right.. But SolidTube was CF output (and ECC83)

 

[rock soderstrom]

You're off course right.. But SolidTube was CF output (and ECC83)

Right, this microphone also still exists. But it can't be on the list because it is a composite circuit of anode and cathode follower. There are quite a few of these, for example all the "CCDA" mics from Asia or the old M series mics from Thiele. (By the way, the Thiele mics probably have the PSU with the fewest components of any mic ever + 2M anode resistor in the 1st stage!)

My list is only for pure cathode followers!

 

[gyraf]

Radiometer "Kunstigt øre" (artificial ear)

 

[rock soderstrom]

Some voices on the internet claim that the Groove Tubes MD3a is a clone of the Sony C37a.

The capsule seems to be similar, built by David Josephson, which also has this externally accessible screw for adjusting the polar pattern.



I have only found a schematic of the MD3 here in the groupdiy archive, which also shows a composite circuit of common cathode and cathode follower with a 12AT7. The GT MD3a doesn't seem to be a 100% clone, right?

 

[leadbreath]

I believe Talk Talks Spirit of Eden was mostly recorded with single room miked C37??
Beautiful sounding...

 

[k brown]

Some voices on the internet claim that the Groove Tubes MD3a is a clone of the Sony C37a.

The capsule seems to be similar, built by David Josephson, which also has this externally accessible screw for adjusting the polar pattern.

View attachment 106858

I have only found a schematic of the MD3 here in the groupdiy archive, which also shows a composite circuit of common cathode and cathode follower with a 12AT7. The GT MD3a doesn't seem to be a 100% clone, right?

View attachment 106859

That grille is an absolutely horrible idea; but that of the C-37A was even worse - was the weakest part of it's design. I've always wondered how much better it would sound with a proper mesh grille, as Royer has done with the MA-37.