Oktava MK-319 output level increase.

[vmanj]

Without a resistor R3, there is no divider and the voltage on the fet is 21v, and with a resistor - 14v. That's why the sound has changed.
And if you do without voltage divider biasing as the picture shows ?

The u87 has a similar circuit (in the image in a simplified form), but there is no mixed bias, but just a voltage divider (according to a different principle).
Why did the engineers of Octave 319 complicate things with offset so much?
It is unlikely that this greatly improved the sound 319...

 

[abbey road d enfer]

Without a resistor R3, there is no divider and the voltage on the fet is 21v, and with a resistor - 14v. That's why the sound has changed.

I don't think that the small change in quiescent current results in significant difference in sound. there may be a (very)little more gain, but that's all.

And if you do without voltage divider biasing as the picture shows ?

It will be similar to the situation where you disconnect R3.

Why did the engineers of Octave 319 complicate things with offset so much?

Somebody already answered that. It makes the circuit more tolearnt to the variations in FET's characteristics; remeber that FET's come with a very large tolerance, about -50/+100%. In the U87, the FET is factory selected.

It is unlikely that this greatly improved the sound 319...

They didn't do this for sonic reasons, more for industrial reasons.

 

[vmanj]

This mic is a bunch of compromises ... starting with the resonators on the capsule ...
Poor shielding of reed switches, etc..

It seems to me that this microphone was generally created not for sound reasons, but for industrial ones..

 

[abbey road d enfer]

It seems to me that this microphone was generally created not for sound reasons, but for industrial ones..

Isn't it the case of 99.9% of manufactured items?
Welcome to the real world! (I haven't found the "cynical" emoticon...)

 

[vmanj]

- !!!
I agree that in today's real world, industry does not complicate, but simplifies production.
And in the octave it's the other way around ..
In the beginning, engineers create a bunch of problems that spoil the sound.
Then they try to solve them in a complex, costly and ineffective way.
In my opinion, I was mistaken, these are not even industrial reasons.
And what .. ??

 

[abbey road d enfer]

- !!!
I agree that in today's real world, industry does not complicate, but simplifies production.
And in the octave it's the other way around ..
In the beginning, engineers create a bunch of problems that spoil the sound.
Then they try to solve them in a complex, costly and ineffective way.
In my opinion, I was mistaken, these are not even industrial reasons.
And what .. ??

Your opinion shows that you don't encompass all the complexity of industrial production.
Adding a few components that cost pennies in order to make a product more tolearnt to production variations is not ineffective, on the contrary.

 

[vmanj]

Everything is correct, but why do this initially make a round wheel square, and made of durable expensive material (which is difficult to process).
You still have to give it a normal round shape and this process is not cheap ...

 

[abbey road d enfer]

Everything is correct, but why do this initially make a round wheel square, and made of durable expensive material (which is difficult to process).
You still have to give it a normal round shape and this process is not cheap ...

I'm not sure I understand what you mean...Is it a figure of speech of sorts?
I don't think the Oktava designers made the circuit overly complex.
I'm not an advocare of "less is more"; I maintain that if the design brief results in adding components, it must be done, or the design brief must be changed.
Whatever it takes to make a thing work as expected is rightfully there.

 

[Khron]

Everything is correct, but why do this initially make a round wheel square, and made of durable expensive material (which is difficult to process).
You still have to give it a normal round shape and this process is not cheap ...

What Abbey was trying to say was that, adding a couple resistors (which cost next to nothing) in order to be able to use a wider range of JFETs is an infinitely lower cost, than individually measuring each JFET (labor is NOT free), and end up not being able to use half of them. Or worse, even if not individually measuring them, then ending up with who knows how many completed mic circuit boards that are unusable, and which then need to be either reworked, or trashed.

Not that the "selected" JFETs would give much (if any) improvement in "sound" anyway...

https://en.wikipedia.org/wiki/Cost–benefit_analysis

 

[abbey road d enfer]

Everything is correct, but why do this initially make a round wheel square, and made of durable expensive material (which is difficult to process).
You still have to give it a normal round shape and this process is not cheap ...

Please have a look at the attached circuits. they both do the same thing, have the same gain and the same number of components. Why would i choose one over the other, in an industrial context?

 

[vmanj]

What Abbey was trying to say was that, adding a couple resistors (which cost next to nothing)

If only a few extra resistors ..
In this microphone, almost everything is a compromise.
Starting with a bell-ringing aluminum microphone body, a strange capsule with a resonator (which nevertheless does not sound good), a strange grid on a grill, reversed phase at the output.
But the most interesting thing is that the microphone has a low-frequency background when it is on the stand, and especially strong when you bring your hand to the reed switches on the back of the microphone.
All this is from slots and insufficient shielding of reed switches ..
To remove this background, I had to cut out a copper plate with a dielectric, ground it and place it between the magnets and reed switches ..
This already looks like not a compromise, but a manufacturing defect.

 

[abbey road d enfer]

If only a few extra resistors ..
In this microphone, almost everything is a compromise.
Starting with a bell-ringing aluminum microphone body, a strange capsule with a resonator (which nevertheless does not sound good), a strange grid on a grill, reversed phase at the output.

These are not compromises, they are defects. Compromises are perfectly acceptable (as long as they are justifiable), defects are not.

 

[shabtek]

I have 2 of these, my first ldc: bypassing the reed switches made them quieter. 1 sounded good the other not good by comparison. Both purchased ca. 2000-2001 at guitar center at same time. The components inside are different manufacturers—same pcb but different runs. I think qc was all over the place. There are soviet era caps in one and budget asian caps in the other... both currently in pieces

 

[vmanj]

Please have a look at the attached circuits. they both do the same thing, have the same gain and the same number of components. Why would i choose one over the other, in an industrial context?

If you want to produce an expensive and high-quality product (not in a very large circulation, then none of the options.
I think that we need to simplify the scheme and use the selected fet, recalculate it for the desired gain.

If you want to make a cheap, not very high-quality product and in a large circulation, then most likely you need to use the first option, although perhaps I'm wrong.

 

[vmanj]

I have 2 of these, my first ldc: bypassing the reed switches made them quieter. 1 sounded good the other not good by comparison.

You're right.
Even if they were collected not in Asia but in Soviet times, the range of sound parameters is enormous ..

 

[abbey road d enfer]

If you want to produce an expensive and high-quality product (not in a very large circulation, then none of the options.
I think that we need to simplify the scheme and use the selected fet, recalculate it for the desired gain.

If you want to make a cheap, not very high-quality product and in a large circulation, then most likely you need to use the first option, although perhaps I'm wrong.

Your answer just shows that you don't understand much about electronics.
With your suggested schemo, how do you control gain and operating point?

 

[vmanj]

Your answer just shows that you don't understand much about electronics.

Of course, I'm not an engineer and for me it's just a hobby ..
But regardless of this, I'm trying to reason logically for what purpose the engineers of this microphone created this horror ..
The microphone has a bunch of defects, some "crutches-patches" in the circuit .. in the form of "adding a few components that cost pennies in order to make a product more tolearnt to production variations"..
It would be understandable if this microphone was commercially successful and expensive ... well, or sounded good ...
Judging by the reviews on the Internet, it is mostly bought as a "semi-finished product" for further improvement.

 

[vmanj]

With your suggested schemo, how do you control gain and operating point?

As I wrote above - electronics for me is just a hobby, so I did not (and could not) "invent a bicycle", but simply took the classic circuit that is used in the excellent u87 microphone.

I wonder why Neumann engineers can do without "adding a few penny elements," and they somehow succeed ??

 

[abbey road d enfer]

As I wrote above - electronics for me is just a hobby, so I did not (and could not) "invent a bicycle",

Then please refrain expressing unfunded criticism. Had you asked "why did they do it that way?", you may have received a more constructive answer, and learnt something.

but simply took the classic circuit that is used in the excellent u87 microphone without any "adding a few components that cost pennies"...

You don't understand that "adding a few components that cost pennies" is a very significant part of an engineer's work. A scientist may design a circuit that works superbly, but it takes an engineer to make it a manufacturable product.
Regarding the U87 circuit, you may want to think why it's been replaced by a more complex circuit in the U89.

 

[vmanj]

Then please refrain expressing unfunded criticism. Had you asked "why did they do it that way?", you may have received a more constructive answer, and learnt something.

Sorry.
- Why did they do it that way ?