OKTAVA 219 MODS
The 219 and 319 are very good microphones but have a few circuit issues and body resonance. You could search the dorsey mod and that will give you a lot of info. I've even emailed him a few times. Very knowledgable and helpful.
219 Basket Mod:
- Take both layers of grille out from the inside of each side of the body. Now using a good/big wire clippers snip off the outer grille supports. When all of them are gone, use a file to even out the metal with the rest of the body. After that use black paint or a paint pen to mask the metal. Now replace 1 or both layers of grille material to each side of the body. Fasten with a epoxy or RTV
219/319 Capsule centering MoD:
- The stock placement of the capsule is too high up in the headbasket. Remove the spacer between the capsule and phenolic/garolite divider. You may have to cut a slot on each side of the divider with a clipper so that you can screw the capsule back on to the mount. This mod centers the capsule for a more even response.
219/319 Damping MoD:
- Use silicone or some kind of rubberized caulking to fill the spaces between the pc board and each side of the case (219). Apply to each side and let cure for 12-24 hours. Make sure it does not touch the pc board. you can use some foam to do that if you want more damping.
- Replace the Fet with a 2sk170BL, 2sk30, j305, 2n3819, or audio fet of your choice. Use data sheets to make sure of proper pin placement.
- Calibration: Using a function generator, apply a 1khz signal to the capsule/fet input capacitor c2. Hook a Oscilloscope to the drain of the fet. Use a 5k trim pot in place of r7 and another trim pot in the place of r8. Start with them set at the values of the resistors that were there. Apply phantom power to the microphone. Now increase the level of the function generator and you will see one side of the wave form clip. Adust the pots to lessen the distortion. Decrease then increase again. May take quite a few tries to dial it in. Calibration is done when both sides of the waveform clip at the same time when increasing the level of the generator. Power off the microphone, remove the calibration equipment and using a ohm-meter, measure the pots to see what values of resistors to put in place of r7, and r8.
- Replace r1 and r2 with 1G ohm resistors
- Replace c2 with a 820 - 1000pf polystyrene, polypropelene, or COG ceramic capacitor 63v or greater.
- Replace c7 and C9 with 2.2u 63v film caps
- Replace c8 with a 1u 63v film cap (I usually bypass this with a .01u polystyrene cap)
- Remove the reed switches by unsoldering them or the wires that go to the daughterboard.
- Note: I usually burn in my film caps by running audio through them for 200-400 hours before installing them in any equipment.
Disclaimer: I encourage people to DIY and I'm here in a informative role.
ModDefecation is about making equipment sound better, providing knowledge and support, repairing that awesome piece of gear, and custom builds. Send me you questions or Ideas.