Oktava mods are back

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Big Kenny

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Flatpicker (Tim Hardin) modded my Oktaba's with polyfilm caps and poly-styrene caps between the capsule and the FET. I liked them before and they are even better now. They have a depth they didn't have before and a dimension that is hard to describe. They aren't as dark and are definitely well defined.
If anyone has the extra $ and was on the fence.... jump. I am thrilled.
I just ran a couple tests against another set of Oktavas and my Neumann 184's. The old MK012's sound a little blah in comparison and while I think the 184's may have a bit more definition, the Modded Oktabas present a better picture of the guitar and how it sound in real life.
NIce job picker!
 
how can I get these mods done? How much would it take?

Jacob
 
Big Kenny said:
Flatpicker (Tim Hardin) modded my Oktaba's with polyfilm caps and poly-styrene caps between the capsule and the FET. I liked them before and they are even better now.
Click to expand...
Is that the only change that he made? Scott Dorsey's article suggests several other significant changes in addition to the blocking cap. Most notably replacing the stage 1 FET and changing the value of the bias and leak resistors. Changing the resistors improves the mics frequency response. Replacing the FET improves linearity. Scott also recommends replacing the capacitor between the FETs.
 
No, there were other things as well. I'll let Flatpicker chime in and get specific. You can get in touch with him about how much and how long it takes and the like
Here's a quote from one of his emails "I really like what that polyester film cap does to the midrange. Plus the polystyrene cap between the capsule and FET just opens it up for that 3-D effect. I don't have a clue why they don't use those in there to begin with because they don't cost that much more."
 
will it work on Chinese Oktavas too? i'm pretty sure mine are chinese since i bought em from GC and they fit the description of the fake oktavas i've read.
 
For the record, I replaced the ceramic cap between the FET and capsule with a polystyrene (my "condenser mic guru" friend, Gus Smalley turned me on to these), replaced the stock FET with a 2SK170BL, the electrolytic cap between the FET's source and the bi-polar's base with a poly-film, and replaced the capsule bias and FET bias resistors with 2G ohms each. The electrolytics should also be replaced if they are the old wet tantalum type, but I have yet to see a MC012 that had these in them. Also, I've never heard an improvement by replacing the bi-polar transistor, so I don't usually replace those either.

Kenny had some interesting remarks when comparing his modified MC012s to his 184s. I don't own a pair of these (sold my last one about a year ago), but I'm beginning to wish I still had a couple.
 
Flatpicker said:
For the record, I replaced the ceramic cap between the FET and capsule with a polystyrene (my "condenser mic guru" friend, Gus Smalley turned me on to these), replaced the stock FET with a 2SK170BL, the electrolytic cap between the FET's source and the bi-polar's base with a poly-film, and replaced the capsule bias and FET bias resistors with 2G ohms each. The electrolytics should also be replaced if they are the old wet tantalum type, but I have yet to see a MC012 that had these in them. Also, I've never heard an improvement by replacing the bi-polar transistor, so I don't usually replace those either.

Kenny had some interesting remarks when comparing his modified MC012s to his 184s. I don't own a pair of these (sold my last one about a year ago), but I'm beginning to wish I still had a couple.
Click to expand...

See? that's why I didn't tell ya, I only know how it sounds.
 
Flatpicker said:
For the record, I replaced the ceramic cap between the FET and capsule with a polystyrene (my "condenser mic guru" friend, Gus Smalley turned me on to these), replaced the stock FET with a 2SK170BL, the electrolytic cap between the FET's source and the bi-polar's base with a poly-film, and replaced the capsule bias and FET bias resistors with 2G ohms each. The electrolytics should also be replaced if they are the old wet tantalum type, but I have yet to see a MC012 that had these in them. Also, I've never heard an improvement by replacing the bi-polar transistor, so I don't usually replace those either.
Click to expand...

Could you please post a schemo? I've got the MXL603s and from the sound of things the MC012 has a very similar topology. I've done the polystrene cap upgrade to the 603's but not the FET or the FET to BJT blocking caps. What impact would the second cap mod achieve? Hmm, just remembered I finally got some 1G's laying around, maybe I'll series a couple up and swap out the stock 1G's.
 
Flatpicker said:
For the record, I replaced the ceramic cap between the FET and capsule with a polystyrene (my "condenser mic guru" friend, Gus Smalley turned me on to these), replaced the stock FET with a 2SK170BL, the electrolytic cap between the FET's source and the bi-polar's base with a poly-film, and replaced the capsule bias and FET bias resistors with 2G ohms each. The electrolytics should also be replaced if they are the old wet tantalum type, but I have yet to see a MC012 that had these in them. Also, I've never heard an improvement by replacing the bi-polar transistor, so I don't usually replace those either.
Click to expand...
Thanks, that sounds like a pretty complete upgrade, and your components sound like good choices. Can I ask you a question? The original value for the bias and leak resistors is 680M, and I see that you increase it to 2G. What would be the impact of increasing it even more? I found some 5G resistors at our local surplus house.

And where on earth can you buy film and polystyrene caps without having to buy 1000 of them?
 
reshp1 said:
Could you please post a schemo...
Click to expand...
I had this one online at one time, but the location was the same as my email and I got spammed to death. When I tried to deactivate the address, I lost everything I had up loaded.

I've got the MXL603s and from the sound of things the MC012 has a very similar topology.
Click to expand...
As far as mods they are similar between capsule and the FET. After that they are more different. The FETs in the MXLs are usually already 2SK170s. May be biased a little differently, though.

What impact would the second cap mod achieve?
Click to expand...
Over all better sound quality I guess. The 603s have 2 caps here and it's such a tight fit, replacing them with something decent is difficult. On the MC012s there's only one cap, usually an electrolytic and they tend to sound too harsh on the top end. The poly film smooths out the top and sounds more natural.
 
Gilliland said:
What would be the impact of increasing it even more? I found some 5G resistors at our local surplus house.
Click to expand...
I've used 2.5Gs which worked fine, but don't know about 5Gs. Are they small enough that you could put two in parallel? That would make 2.5Gs.

And where on earth can you buy film and polystyrene caps without having to buy 1000 of them?
Click to expand...
Mouser.
 
Flatpicker said:
I've used 2.5Gs which worked fine, but don't know about 5Gs. Are they small enough that you could put two in parallel? That would make 2.5Gs.
Click to expand...
I doubt it. They're small enough that one can fit fairly easily, but squeezing in a pair of them would be a challenge. I might be able to add the second one on the other side of the board, but I'm not sure I want to try that. They're a typical cylindrical resistor, about 6mm long and 3mm in diameter. I've got a note into Scott Dorsey asking him the same question, but he's in Europe at the moment. My guess is that the 5G should be OK, but it's nothing more than a guess - I don't have the background to really analyze the circuit.

I just pulled the mic apart to check the spacing, and it might just be possible to put two in parallel. Tight, but it looks like it might fit. So that might be a possibility. Of course, I'll have to go back and get a few more now (I've got a pair of MC012s to modify). But they were only a nickel each (the resistors, that is, not the mics <g>).

Thanks for the pointer to Mouser - no minimum order, that's what I like to hear.
 
Gilliland said:
I might be able to add the second one on the other side of the board, but I'm not sure I want to try that.
Click to expand...
Actually that would probably work well, but try 5Gs first - they may sound as good or even better!
 
Flatpicker said:
Actually that would probably work well, but try 5Gs first - they may sound as good or even better!
Click to expand...
I exchanged emails with Scott Dorsey about it, and he said that 5G should work OK. His only caveat was that it might take a bit longer for the mic to stabilize when first powered up. As far as I'm concerned, that's not an issue. So I'll give them a try. But I've still got to track down some decent caps for C1 before I'm ready to warm up my soldering iron.
 
zed32 said:
will it work on Chinese Oktavas too? i'm pretty sure mine are chinese since i bought em from GC and they fit the description of the fake oktavas i've read.
Click to expand...

^
Yeah what he said...
 
I haven't heard of anyone actually investigating the counterfeit Octavas. Without someone opening one up and tracing the circuitry, there's no way to know whether or not Scott's mod would apply to them. I guess the question is - how far did the Chinese go in copying the original? Did they literally copy the circuit, or did they use a design of their own?

(And from what I've heard about the Chinese counterfeits, they could use any help that they can get!)
 
The Chinese-manufactured copies of Oktava LDCs instigated by the the McKay brothers (originally-authorized distributors) are exact circuit copies. The McKay's either didn't care or know enough to instruct their Chinese vendor to copy the sound of the Russian mics exactly.

The copies I've seen have been very consistant. This particular vendor does high quality work.

Perhaps it would be more correct if we start refering to the non-Russian mics as "McKay conterfeit mics" - the Chinese vendor simply executed a work order for a product they thought was being legitimately handed to them. This would also lay the responsibility for the copies where it belongs - at the feet of the McKays. I travelled to China for work in '89 and '91, had great experiences there. We're doing a disservice to the ingenuity and honest hard work Chinese manufacturers deliver when we continue to slag off "Chinese copies".

Anyway, as far as the McKay MK319 goes - I've had lots of them apart. Even after they're mod'd, I'm hearing a difference compared to a Russian MK-319. The copies are missing a certain righteous mid-range richness a good Oktava LDC mic is capable of. I have not analyzed yet whether this is due to capsule tuning issues (the capsules look identical) or transformer nonlinearities or both. When I get my head above water from a recent crush of mod work I intend to look at both issues.

The LDC Oktava copies are not bad mics. Its just that a bit of magic is gone.

re: the '012 copies - This thread is good:
http://debris.com/journal/1274

The '012s are exact circuit copies, so Scott Dorsey's mods would work here. However, the capsule connectivity is inferior to the Russian original. This might lead to some long term oxidation of the contacts that could affect signal purity (Could be cleaned and burnished periodically though). It seems the jury is still out on whether or not the capsule itself was copied succesfully.
 
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zed32 said:
will it work on Chinese Oktavas too? i'm pretty sure mine are chinese since i bought em from GC and they fit the description of the fake oktavas i've read.
Click to expand...
Sorry I forgot to answer this for everyone, but I think Michael just did. Don't know for sure, but I'm betting the improvements are similar.
 
MichaelJoly said:
I travelled to China for work in '89 and '91, had great experiences there. We're doing a disservice to the ingenuity and honest hard work Chinese manufacturers deliver when we continue to slag off "Chinese copies".

I'm hearing a difference compared to a Russian MK-319. The copies are missing a certain righteous mid-range richness a good Oktava LDC mic is capable of.
The LDC Oktava copies are not bad mics. Its just that a bit of magic is gone.

.....However, the capsule connectivity is inferior to the Russian original. This might lead to some long term oxidation of the contacts that could affect signal purity.
Click to expand...

There's a bit of a disconnect above. I work with Chinese factories too, and while I certainly have nothing against the very hard working and very poor people who work those factories, often in bad conditions with no worker protections of any kind, I do have to constantly check that the factories aren't cutting corners. They pull stunts all the time with our designs, sometimes just substituting inferior components, sometimes doing an actual re-design for cost cutting that we never agreed to. Plastics will change without us knowing, and susequesnt drop tests fail miserably. None of this is the fault of the workers, it's all about corporate greed, which is prevelant on both sides of the Pacific.
So I don't think we're doing a disservice to anyone when denouncing inferior products. I don't care where something was built, but I do care how it was built and how it works.

-RD
 
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