Alctron BV300 (T.Bone Retro Tube II) to half of AKG C24 mod

[LevinGuitar]

Yes, it does something, but not enough for my ears. In the Retro Tube mic, C11 is soldered under the tube socket, so is not easy to change the value there. I removed it and connected a 390pf cap after second stage cathode (to ground), before output capacitor.

 

[abbey road d enfer]

Yes, it does something, but not enough for my ears. In the Retro Tube mic, C11 is soldered under the tube socket, so is not easy to change the value there. I removed it and connected a 390pf cap after second stage cathode (to ground), before output capacitor.

Useless in this position. The output impedance of the cathode follower is very low, so the capacitor does nothing. You would need to increase the value enormously to hear anything, but then you would probably hear a lot of distortion. You really need to connect it to the grid of the second stage or to the anode of the first stage.
But after all, why not leave it as it is, and process the signal later, in the preamp, or in the DAW (or whatever you use to record)?
Any kind of EQ you can do in the mic, you can do ten times better with a half-decent EQ.

 

[xeawr]

they didn't skimp on the 220pf C11... it's a real WIMA.

Maybe it's important and we're missing something here?

 

[xeawr]

I'm modding my Retro Tube and wonder what R11 is for, the apex 460 don't have it and the Rode NTV have a 0.22uf cap + 200R resistor there. Is it filtering something?
And why C11 is there and not after cathode? Is there no difference where to place the HF roll of?

Thanks!

R11 and C11 form a low pass filter at around 30kHz, going into the grid of the second half of the triode.

thanks abbey road for pointing my mistake out!

 

[abbey road d enfer]

R11 and C11 form a high pass filter at around 72Hz, going into the grid of the second half of the triode.

No. It's a low pass filter at about 30kHz. Probably there more for stability than actual tone control.

 

[xeawr]

I've modded two Alctron BV300 and still have one t.bone Retro Tube. They are identical except for the cosmetics.

I'm curious to hear from you LevinGuitar, what your success was in modding these mics.

I've converted both mics to "plate out", removing the cathode follower. I've also replaced all caps in the signal path with brand types and tried out pp/pet caps in one vs ps/pp caps in the other. The polystyrene/polypropylene version sounded smoother and more natural, the pp/pet a little more "plasticky", for lack of a better term.

What was really surprising to me was modding the power supply and replacing the electrolytic caps with brand types. I have 5 power supplies in total, so going back and forth and blind-testing was really revealing. I would have never believed I could hear the differences a modded power supply makes.

Note also, that I only do blind tests where I listen to recorded samples that are perfectly level matched (with the same tube).

To sum it up: I'm not happy with the sound, The corniness that was there before is now even more apparent. I'm considering a capsule swap, but I haven't had the (time or) money for a maiku capsule.

What are your results?

 

[LevinGuitar]

I forgot this mic until your quote, today I tried a 5840 tube and seems to have a interesting results even with original transformer (I used a 1uf MBM capacitor). Just low gain and some noise that have to look where it come from. The psu gives 145v, so I just adjusted bias for 1.5v on cathode.

I've modded two Alctron BV300 and still have one t.bone Retro Tube. They are identical except for the cosmetics.

I'm curious to hear from you LevinGuitar, what your success was in modding these mics.

I've converted both mics to "plate out", removing the cathode follower. I've also replaced all caps in the signal path with brand types and tried out pp/pet caps in one vs ps/pp caps in the other. The polystyrene/polypropylene version sounded smoother and more natural, the pp/pet a little more "plasticky", for lack of a better term.

What was really surprising to me was modding the power supply and replacing the electrolytic caps with brand types. I have 5 power supplies in total, so going back and forth and blind-testing was really revealing. I would have never believed I could hear the differences a modded power supply makes.

Note also, that I only do blind tests where I listen to recorded samples that are perfectly level matched (with the same tube).

To sum it up: I'm not happy with the sound, The corniness that was there before is now even more apparent. I'm considering a capsule swap, but I haven't had the (time or) money for a maiku capsule.

What are your results?

 

[xeawr]

I forgot this mic until your quote, today I tried a 5840 tube and seems to have a interesting results even with original transformer (I used a 1uf MBM capacitor). Just low gain and some noise that have to look where it come from. The psu gives 145v, so I just adjusted bias for 1.5v on cathode.

thanks for your response!!!