Octava MK/MC 319 Mods

[maestro_dmc]

The parts list in the manual calls for 2 X 68pf caps but 680pf caps are
fitted.

You got a Manual?!

I didn't get a manual. I picked up two of the 319's at G.C. All I got was a lousy soft case and a ring style mic holder.

'Course I only paid $50 bucks each for the mics, so I really shouldn't complain.

 

[demto]

Octava MK319 mods

To Maestro

Life is not fair, it.

Some are born with Manuals. Some achieve Manuals. Others have Manuals
thrust upon them.

I had a Manual thrust upon me when I bought the mike.

Bearing in mind that I paid the equivalent of $350 when I bought it a few
years ago its the least they could do. Most things in the UK are VERY
expensive compared with the USA.

Go to the link Crazydoc mentions in his post. You will see a excellent wiring
diagram which was posted by Flatpicker. Thank god for Flatpicker I say.

 

[Flatpicker]

Go to the link Crazydoc mentions in his post. You will see a excellent wiring diagram which was posted by Flatpicker. Thank god for Flatpicker I say.

Uhh..... Ok..... You're welcome!

And thank you, crazydoc, for posting the link.

(Actually, I posted a link to the same diagram a few post up.)

 

[Flatpicker]

I basically swapped out all the lower quality caps for higher quality ones everywhere I could and I think I added .1 uF polypropylene cascaded (shunt) caps on the electrolytics...Bob

C8 is the only ele directly in the signal's path so I just swapped it out with a 3.3uF metal film. Bypassing C3 with a .1uF might help too. Haven't tried that yet...

I also ripped out the inner screen which was easy. Gives the mic a more open sound...

Haven't tried that yet either, but I'm sure it helps. I wish I had time to mess with mine some more, but there's too many irons in the fire!

BTW, Bob, did you end up leaving the disk on or taking it off?

 

[Bob's Mods]

It's been some time since I fussed with that mic. I'm not recalling a "disk". Rattle my brain.

 

[Marik]

It's been some time since I fussed with that mic. I'm not recalling a "disk". Rattle my brain.

Look at capsule itself. The plastic jobby with big holes right in front of it is the one... Huh... Another resonant chamber to overcome the flaws of initial design... Should I say more...

 

[Bob's Mods]

I see a black plastic frame with multiple hole sizes on both the front and back of the capsule. I did not remove either of the pieces. I'm not sure I want to take it to that level. If the capsul gets damaged my cheap mic would then morph into a fully functional blackjack.

 

[crazydoc]

I'm not sure I want to take it to that level. If the capsul gets damaged my cheap mic would then morph into a fully functional blackjack.

C'mon, live a little. Take them off. A naked capsule is a thing of beauty

 

[Bob's Mods]

I believe that plastic disk effects the pickup pattern more than effect resonance. It's probably easiest to carefully cut out the center section with a sharp pair of cutters. If anyone has successfully removed it, please enlighten us as to what changed.

Bob

 

[MichaelJoly]

Oktava Capsule HF Boost discs

Removing the discs by uncrewing them and the center conductor is safer than trying to bite away at the plastic with cutters in my opinion.

When installed, the perforated HF resonators on the Oktava large diaphragm capsule boost 3.5dB @ 10kHz and contribute to a notch in the 3kHz to 5kHz range. Removing the discs does two things:

1.) Flattens high frequency response above 3kHz and allows a more gentle rolloff above 10kHz.

2.) Improves transient response and HF phase acuracy - I haven't quantified this with impulse test equipment but the result is clearly audible. For example the spoken sentence "she sells sea shells by the she shore" sounds more like "she shells she shells by the she shore" when recorded by an unmodified Oktava large diagragm capsule when compared to a mic with the HF boost disc removed. The HF boost discs impart HF delays that are audible as time-smeared treble response.

Similarly, the HF content-rich spoken letter "F" sounds much more smeared with the HF discs in place compared to when they are removed. The noise content of the letter "F" sound is exagerated with the HF boost disc installed.

The slotted grille / 2 layer wire mesh design of the unmodified MK-219 also contributes to the notch in the 3kHz-5kHz range and HF smearing do to reflections within the headgrille. Modifying the head grille and capsule as shown in the photo at the link below provides much clearer and more accurate HF response.

 

[MichaelJoly]

MK-319 Bottle Mod

A couple of years ago I was on a DIY Bottle Mic bender. I got obsessed with the idea that mic bodies and capsule housings contribute to HF phase problems and smear detail etc.

So I started looking for ways to clear up HF transient response in the Oktavas. The strategy is simple - get the capsule out in the open air as much as possible and keep reflective surfaces as small and as far away as possible.

In practice, this has meant removing the HF boost discs, removing all but one layer of wire mesh, and yes, hacking the capsule housing to make it more open and further removed from the mic body.

 

[MichaelJoly]

Oktava / "Dorsey Mod" Bottle

One mod leads to another when you're on a bottle mic bender.

I like to work with bronze window screen - easy and cheap to get at your local hardware store.

The link below is to a pic of an Omni-modified MK-319 capsule sitting in a lollipop-style capsule housing suspended well above a "bottle" body. The body contains the "Dorsey" mod, a Shoeps-inspired FET headamp and FET balanced output stage.

I love this thing as a room mic - big and clear with great transient response.

 

[MichaelJoly]

Big Head, Little Body

The large diaphragm lomo M1 capsule for the MC-012 body inspired me to DIY my own version.

The idea of a large capsule being underbiased by the small diaphragm-design FET amp in the MC-012 to produce a unique sound intrigued me.

I took one of the better MXL capsule and head assemblies and fit a mounting collar to it that could screw on and off the MC-012 body. I actually used the stock MC-012 -10dB collar rewired for flat gain as the mounting attachment between the MXL capsule head and the MC-012 body. The MXL grille is now also single layer wire mesh instead of two-layer.

I like the small diaphragm / large diaphragm flexibility of this mod and the body now sports a Dave Royer-inspired 5840 subminiture tube mod also.

 

[Bob's Mods]

I pulled the plastic plates off both the front and back. I thought when I pulled out the inner screen the thing opened up but this opens this thing nicely even more. I just recorded a great acoustic track.
This mic has got to be the best bang for the buck with mods than any other. Rather simple mods boost the preformance of this big time. What the hell were those Rue-skies thinking anyway?

 

[crazydoc]

Michael - those are some fantastic looking mics - from a time and a place far, far away. I bet the sound is from another dimension also.

The link below is to a pic of an Omni-modified MK-319 capsule sitting in a lollipop-style capsule housing suspended well above a "bottle" body.

How did you do the omni modification?

 

[MichaelJoly]

Far Away Dimension X Mods

Crazydoc - thanks for the kind words

These mics are little sound sculptures for me. I've intentionally limited my palate almost exclusively to Oktavas because I have an irrational love for them and I like having a family of mics where each member is a slightly eccentric but functional chip off the old block.

Or to switch metaphors, these mics are little poems in metal. I think that's closer to what I'm trying to do with them. I'm trying to blend my experiences in sound with the workers who built these little tanks of tone. An alchemical fusion of the spirit and intent of people separated by time and place.

Poetics and sculpture aside, I want to make them better but have them retain their souls. oops, damn metaphysics floats in again. I'll try again...

...body resonance damping, capacitor upgrades, head grille opening, capsule mods, FET upgrade, tube conversion...produce results that could be quantified electrically. But that's not really nessessary.

The soul of the mic is the thing.

Marik has talked about his early days in Russia and how Russian equipment was built to be re-built when needed. I find it an interesting footnote to the MK-219 / 319 story that the '219 originally shipped with its Russian language manual including parts lists, schematics and an individually-drawn frequency response chart. These are not the halmarks of a cheap mic. After just a few years in the West, the mic has been stripped of all that attention to detail - as if no one in the West really cared to study its schematic, gaze at its curves and read the universal language of kOhms, uV, mH, and uF printed in the parts lists.

So Crazydoc, you got it right when you sense these mic are a from a time and place far, far away - a dimension who's inhabitants regard peices of sound technology as brother beings.

Ps - special off topic bonus for Oktava lovers - ML-52 hack below...

 

[MichaelJoly]

oh yeah, the Omni Mod

duh, all that and I didn't answer the question. Typical.

Just take a '219 or '319 apart, tear off the back diaphragm and put some 5 minute epoxy into the labyrinth. Eliminates the cardioid cancellation pattern normally produced by the delayed back wave reaching the front diaphragm.

 

[Marik]

Michael,

So good to see you again. I missed you and your talking about mics in your usual poetical way, but now I see that you've been busy with your mics--beautiful work. Are you still recovering from the move?

Re: omni. In theory, the omni capsule should be stiffness controlled and tuned into top range. That's the reason why they don't do LD true omnies--too large to get good and long lasting tension. Decrease of back-chamber volume with sealing the back helps to increase tuning resonance. Have you had chance to measure it?
How its top end? On the other hand, knowing your passion for "Russian sound", I am sure some top roll off would not bother you much... Or is it a theory, which doesn't exactly work this way in practice? Anyway, tell what do you think about it.

 

[Flatpicker]

Great stuff Michael! Thanks for posting all of this!

 

[MichaelJoly]

Oktava Omni vs Cardioid Frequency Response

Re: omni. In theory, the omni capsule should be stiffness controlled and tuned into top range. That's the reason why they don't do LD true omnies--too large to get good and long lasting tension. Decrease of back-chamber volume with sealing the back helps to increase tuning resonance. Have you had chance to measure it?
How its top end? On the other hand, knowing your passion for "Russian sound", I am sure some top roll off would not bother you much... .

Still haven't set up my studio and done any recording after the move so I'd say I'm still recovering.

I found my analysis files comparing my omni mod Omni MK-219 with a cardioid MK-219. Both mics have had their HF boost discs removed so the response at 12kHz is down 3.5dB from a stock mic. I'll give the general trend of the high frequency end of the response curves...

Cardioid MK-219, HF boost disc removed:

on-axis:
3kHz 6kHz 12kHz
0dB +2dB +3dB then sharp cutoff above 14kHz

Omni MK-219, HF boost disc removed,

on-axis:
3kHz 6kHz 12kHz
0dB -1dB -3dB

-90 degrees
3kHz 6kHz 12kHz
0dB 0dB -7dB

-180 degrees
3kHz 6kHz 12kHz
0dB -3dB -9dB

then sharp cutoff above 14kHz in all cases.

So my omni mod MK-219 on-axis is down about 9.5dB at 12kHz compared to a completely stock mic, down 6dB from a boost-disc removed mic, but...it is only down 3dB from flat at 12kHz which makes for a good room mic. By aiming the room mic either toward or away from the source I can control the spectral content of the room vs direct sound.

Actually, the on axis sound for close mic'd vocals is pretty nice - there is a clarity that comes with removing the back wave propagation nessessary to create the cardioid pattern. I've used it with great success for voice-over work in a near-anechoic announcers booth

As a point of reference, compare the frequency response of these Octavas with a Studio Projects C1 which is up about 12dB at 12kHz!