Why Are people using the 2sk170BL to upgrade the Oktava 319??

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Paul678

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Here is the article:

        http://marshalserna.com/2010/10/25/diy-oktava-319-mic-mods/

But I just took a 2sk170 out from my SP-1, and replaced it with the faster
slew rate J305, based on Jim William's and others recommendations. 

So unless there is a substantial difference between the 2sk170 and the 2sk170BL,
I have to wonder why they are doing this.  Why not use the J305 to upgrade the
Oktava 319 as well??

Jim Williams described the 2sk170 as "cloudy" sounding.......
 
The stock FET is individually biased for each mic; the according resistor values are penciled on the transformer cover. When you change the FET you need to re-bias. I'm not sure how many people actually do that, so the sound difference they hear may be a FET that's not biased correctly.
 
Rossi said:
The stock FET is individually biased for each mic; the according resistor values are penciled on the transformer cover. When you change the FET you need to re-bias. I'm not sure how many people actually do that, so the sound difference they hear may be a FET that's not biased correctly.
Click to expand...

I'm aware of the re-biasing process, as I had to do it with the J305 in the SP-1:

      http://farm9.staticflickr.com/8248/8561702277_d2da4f614a_c.jpg

So I expect to do this again for the Oktava.

But, does anyone have an accurate schematic for the Oktava 319?
I have one, but not sure if it's correct.

 
Heres a schematic not sure if accurate.....
http://www.gearslutz.com/board/geekslutz-forum/569273-oktava-mk-319-mod-questions-w-pics.html

I re made the MK012 circuit but with a J305 properly biased I kept a factory made Mk012 & a MK319 the J305 circuit sounds a little different but to me no better than originals, didnt bow mw away I do like the sound of the stock MK012 best of the 3 for my ears anyway...... its nice to have more flavors tho....
 
gary o said:
Heres a schematic not sure if accurate.....
http://www.gearslutz.com/board/geekslutz-forum/569273-oktava-mk-319-mod-questions-w-pics.html

I re made the MK012 circuit but with a J305 properly biased I kept a factory made Mk012 & a MK319 the J305 circuit sounds a little different but to me no better than originals, didnt bow mw away I do like the sound of the stock MK012 best of the 3 for my ears anyway...... its nice to have more flavors tho....
Click to expand...

Ok, it appears the original Oktava MK012 used a 2sk170 FET, so it can't be the worst sounding FET in the
world.  And as you have tried the faster J305, and prefer the original circuit, that makes me wonder
a bit.  Someone else wrote that they actually preferred the SLOWER fets, because they were
"creamier".  Perhaps some people prefer a slower slew rate, because there is less higher frequency
content. 

Ok, the "BL" suffix on the 2sk170 refers to the IDSS rating:

http://pdf1.alldatasheet.com/datasheet-pdf/view/30581/TOSHIBA/2SK170.html

The 2sk170 I removed from my SP-1 was a "GR" rating, which is a lower IDSS than the
"BL", so I wonder how it will affect the sound (lower noise?). 

Yeah, your schematic matches the one I found:

          https://www.google.com/search?hl=en&client=firefox-a&hs=s3c&rls=org.mozilla:en-US:eek:fficial&q=oktava+319+schematic&bav=on.2,or.r_qf.&bvm=bv.44442042,d.eWU&biw=1280&bih=895&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&ei=DiZYUfS8FonC9gSLuIHICw#imgrc=Cg7IJDAQnJtvoM%3A%3BTePDT_DQJERbOM%3Bhttp%253A%252F%252Fwww.xaudia.com%252Fomnip%252FMics%252FMicSchLib%252FOktavaMK319.jpg%3Bhttp%253A%252F%252Frecordinghacks.com%252Fmicrophones%252FOktava%252FMK-319%3B664%3B416

But there are no part values, and they don't say what the original FET is.

 
Be aware that there's no bias pot in an MK219/319; the biasing is therefore more complicated. The resistor values penciled on the transformer cover refer to R7 and R8.

I don't think anybody really has a data sheet for the russian FETs used in most Oktavas, so it's probably speculation or mere blah, when people say it's bad or slow. I don't know any FET that couldn't handle full audio bandwidth.

As long as your mic isn't noisy, better keep the stock FET.
 
Here's the official 219 schematic.  The 319 is almost identical - you can certainly work it out from this.

As Rossi points out, two bias resistor values are usually written on the transformer.

I have been round the houses modifying the 219 and 319 mics. There was no real improvement. I eventually sold off all the modified ones and kept a pair of stock 219s, which I like very much. They sound like Oktavas, and there is nothing wrong with that. Just my opinion.
 
IMO there is nothing wrong with the stock Oktava JFETs. They work and are biased correctly stock.

I have worked on a few Oktava 012s and 219s and now I would leave them stock until I found something I did not like about them.


 
Rossi said:
Be aware that there's no bias pot in an MK219/319; the biasing is therefore more complicated. The resistor values penciled on the transformer cover refer to R7 and R8.

I don't think anybody really has a data sheet for the russian FETs used in most Oktavas, so it's probably speculation or mere blah, when people say it's bad or slow. I don't know any FET that couldn't handle full audio bandwidth.

As long as your mic isn't noisy, better keep the stock FET.
Click to expand...

Yes, R7 and R8 create series feedback, and the reactance of C3 is only significant at about 19 Hz, so
for most audio frequencies, R8 is bypassed.  There is also a voltage divider with R3 and R4, for the
gate bias, but if the factory only adjusted R7 and R8, then it's probably best to follow their
procedure.  It wouldn't be difficult to temporarily replace R7 and R8 with a 5k pot, and inject
a 1kHz sine wave into C2, and adjust until the clipping occurs equally at the tops and bottoms
of the sine wave.  Probably best to put your o'scope on the drain.

Again, all of this is subjective in terms of what sounds "good", and some people
like the sound of slower fets.
 
zebra50 said:
Here's the official 219 schematic.  The 319 is almost identical - you can certainly work it out from this.

As Rossi points out, two bias resistor values are usually written on the transformer.

I have been round the houses modifying the 219 and 319 mics. There was no real improvement. I eventually sold off all the modified ones and kept a pair of stock 219s, which I like very much. They sound like Oktavas, and there is nothing wrong with that. Just my opinion.
Click to expand...

So you didn't like the sound of the 319s?  Even with the resonator disk removed?

As you and Gus point out, this is all very subjective.  We ALL hear things differently.  Each person's
ears have unique frequency response curves....EVEN ONE PERSON'S LEFT AND RIGHT
EARS ARE DIFFERENT!!!  For example, my right ear hears shrill high frequency sibilance more than
my left ear.

So it's no wonder everyone has different opinions about which mics are the best sounding, and
which mods are worth doing.
 
Paul678 said:
So you didn't like the sound of the 319s?  Even with the resonator disk removed?
Click to expand...
I didn't say that at all! 
In the end I liked the MK219s, and also my MK18. With the resonator. And the ringing body. I know this is not the fashion.

So it's no wonder everyone has different opinions about which mics are the best sounding, and which mods are worth doing.
Click to expand...
Indeed! Whatever you like is right! Try them all and make your own mind up. Just sharing my own journey.
 
zebra50 said:
Paul678 said:
So you didn't like the sound of the 319s?  Even with the resonator disk removed?
Click to expand...
I didn't say that at all! 
In the end I liked the MK219s, and also my MK18. With the resonator. And the ringing body. I know this is not the fashion.

So it's no wonder everyone has different opinions about which mics are the best sounding, and which mods are worth doing.
Click to expand...
Indeed! Whatever you like is right! Try them all and make your own mind up. Just sharing my own journey.
Click to expand...

  Well, when you write that you sold off your 319s, and kept your 219s, it's obvious the
319s were not your favorite.

    But yeah, it's "fashionable" to like the U-87, for example, but I know some engineers do not like
the sound of them.    Many older mikes, like 30-40 years old, sounded good with tape saturation,
but don't sound good with modern digital recording....

    f**k FASHION.  DO YOUR OWN THING!    8)
 
Yes, not my favourite, but that's not the same as not liking them. I can't keep them all!  (To be honest, I never really like parting with stuff that I have worked on. But I see about 300 mics per year now, so I've had to get over it ;) )

The weird thing, or perhaps not, is that whatever I did to them, they still sound like Oktavas. Eventually I gave up and realised that they are what they are.
 
I've done some work on Oktavas and even wrote a modding article for Sound & Recording Magazine, Germany. Personally, I think MK-219s benefit from removing the outer parts of the grille a lot. Removing the HF resonators is a matter of taste and depends on the sound of the individual capsule. I left it on most of my MK-219s and all of both of my MK-319s. Changed no FETs but did some cap changes (that said, the original caps have a sound of their own). Removing the switches (which create parasitic capacitance in the high impedance parts) helps, too. In the MK-319 you can implement a different switching scheme in the lower impedance part that does not compromise the performance; in the MK-219 there's not enough room for that. I later changed one of my MK-319 to a self-designed tube circuit and developed some more mods that I prefer to keep to myself for the time being. You can have a lot of modding fun with those mics.

Or buy a MK-101 which IMO sounds fine stock.
 
I agree with Rossi the MK101 lollypop head( this dude has classic mics in his possetion) is great as is I bought a MK012 with MK101 head for £167 from Thomann I also have a stock MK319 my friend owns but it lives in my house I prefer the sound of the transformerless MK012 I tried taking the resonator off still sounds good but I prefer it on .....

I was intrigued by all the mods going round about all Oktavas but instead of modding I just built a ugly vero board version of the 012 & tried all the mods on it only a few ££s of parts ..... I find the problem with modding is you lose sight of what it was to start with this way you can still compare, I tried different FETS and caps it was fun & most things sounded great BUT really if Im honest with myself no better just slightly different....... but its nice to have flavors so I still use the vero Oktava as well as stock with same lollypop head a really cheap DIY mic if you just buy a Oktava lollypop capsule I build mic circuits in round choc tins & & use lollypop heads that way I can A & B mic circuits in minutes & develop them the sound seems to be 95% to my ears anyway.

There lots of people making money out of modding mics so lots of talk goes round & its easy to talk your ears into hearing what they want you to hear.....

I am coming out of the mic closet Im glad to be a Oktava fan...

All the best
 
gary o said:
I agree with Rossi the MK101 lollypop head( this dude has classic mics in his possetion) is great as is I bought a MK012 with MK101 head for £167 from Thomann I also have a stock MK319 my friend owns but it lives in my house I prefer the sound of the transformerless MK012 I tried taking the resonator off still sounds good but I prefer it on .....

I was intrigued by all the mods going round about all Oktavas but instead of modding I just built a ugly vero board version of the 012 & tried all the mods on it only a few ££s of parts ..... I find the problem with modding is you lose sight of what it was to start with this way you can still compare, I tried different FETS and caps it was fun & most things sounded great BUT really if Im honest with myself no better just slightly different....... but its nice to have flavors so I still use the vero Oktava as well as stock with same lollypop head a really cheap DIY mic if you just buy a Oktava lollypop capsule I build mic circuits in round choc tins & & use lollypop heads that way I can A & B mic circuits in minutes & develop them the sound seems to be 95% to my ears anyway.

There lots of people making money out of modding mics so lots of talk goes round & its easy to talk your ears into hearing what they want you to hear.....

I am coming out of the mic closet Im glad to be a Oktava fan...

All the best
Click to expand...


  Yes, I agree that a lot of the microphone market is HYPE, pure and simple, both
on the retail level, and the modifications level. 

    But my method to make sure I was actually making progress, was to record the
same song vocally, and same song on acoustic guitar, as I was making the mods,
so I had a clear record of what it sounded like originally, and what it sounds like
with each mod step.

    I'll do the same with the 319 once I get mine in the mail.....

 
Cool I do similar its good to keep a record pardon the pun...... I read the board trcks were fragile so be careful have fun be interested to hear what you think of the mods
 
Paul678 said:
Ok, it appears the original Oktava MK012 used a 2sk170 FET, so it can't be the worst sounding FET in the
world.  And as you have tried the faster J305, and prefer the original circuit, that makes me wonder
a bit.  Someone else wrote that they actually preferred the SLOWER fets, because they were
"creamier".  Perhaps some people prefer a slower slew rate, because there is less higher frequency
content. 
Click to expand...

It's interesting, given that all of these devices are considered "RF" amplifiers, with bandwidth well into the MHz range.
 

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