Microphonics in VF14 and U47

[soliloqueen]

I don't believe the purpose of a microphone is to be transparent or accurate, so I neither convince myself that vintage microphones are somehow able to capture something other microphones aren't nor do I necessarily disparage them for their nonlinearities. They simply are what they are. Like an instrument. This is not really related to what anyone said, just thinking about the results with the u47. It's an argument I see a lot on gear forums elsewhere, especially among connoisseurs. Either we need utmost transparency from the latest technology and vintage gear is high distortion garbage from the dark ages or vintage gears can somehow capture something magical that is definitely there In reality but for some reason newer microphones can't pick up. To me, distortion just sounds good sometimes. The human mind responds positively to harmonic distortion. Many people perceive it as an added intimacy or emotional intensity, so when you are designing a microphone circuit the important thing to do is to manage your distortion to do what you want it to do depending on what you're building the microphone for, just like anything else. It's wild to me that a lot of people understand this with things like guitar amplifier circuits but not with microphone circuits. This is less a problem here and more problem on places like gearspace

 

[soliloqueen]

I think it would be interesting to change up how we think about microphone circuit design. Right now as an industry on the whole, we either build extremely clean microphones with new designs or recreate old designs to get specific kinds of coloration. It would be neat to design a new microphone circuit from the ground up that's distorted on purpose, maybe even in novel ways. This is actually something I am hoping to do with my own brand of microphones down the line.

 

[kingkorg]

I don't believe the purpose of a microphone is to be transparent or accurate, so I neither convince myself that vintage microphones are somehow able to capture something other microphones aren't nor do I necessarily disparage them for their nonlinearities. They simply are what they are. Like an instrument. This is not really related to what anyone said, just thinking about the results with the u47. It's an argument I see a lot on gear forums elsewhere, especially among connoisseurs. Either we need utmost transparency from the latest technology and vintage gear is high distortion garbage from the dark ages or vintage gears can somehow capture something magical that is definitely there In reality but for some reason newer microphones can't pick up. I feel like I'm in the minority in that I simply believe that distortion sounds good sometimes. The human mind responds positively to harmonic distortion. Many people perceive it as an added intimacy, so when you are designing a microphone circuit the important thing to do is to manage your distortion to do what you want it to do depending on what you're building the microphone for, just like anything else. It's wild to me that a lot of people understand this with things like guitar amplifier circuits but not with microphone circuits.

In the guitar world filth, dirt, nonlinearities have been embraced. Probably because they are so obvious and the gear is more available and less expensive.

In mic world somehow, probably due to lack of proper testing equipment and procedures, wrong people spreading wrong facts and big time cork sniffery, the discussion went towards some imaginary superiority of components produced by superior race of human-alien hybrids using technology and materials long gone.

And yes, people who own the gear incidentally profit from the myth. Huge respect for @tomas.borgstrom for doing this.

The effect of the microphonics could be replicated with simple convolution IR. Using the files provided by @tomas.borgstrom

 

[Recording Engineer]

My line of thought from all this is more about better consistency.

soliloqueen, I agree about new mic design. It was my line of thought when heavily-pushing a Lundahl LL1940 with a 396A.

 

[Whoops]

I managed to measure eight VF14 and the results are very informative.

Thank you so much for the test and for sharing your findings. Very informative

In this age of such scarcity of VF14 tubes, how did you manage to have 8 of them available for testing?

 

[Gus]

I think it would be interesting to change up how we think about microphone circuit design. Right now as an industry on the whole, we either build extremely clean microphones with new designs or recreate old designs to get specific kinds of coloration. It would be neat to design a new microphone circuit from the ground up that's distorted on purpose, maybe even in novel ways. This is actually something I am hoping to do with my own brand of microphones down the line.

I built a solid state external powered transformer out microphone years ago with the capsule voltage adjustable from 5 to 70VDC the control is on the power supply(there was picture of it on the now gone site for pictures for the older version of the forum).
The idea was kind of like gain and master volume on a guitar. Turn up the voltage and push the amp in the microphone and adjust the gain in the preamp or turn down the voltage and adjust the gain in the preamp.
I don't like cap pads.

 

[soapfoot]

This is fantastic work. Thanks so much for the time taken to do this and for sharing it publicly

 

[oscarhuang]

This is VF14k from Telefunken. My friend just tear down and this tube cost $750! What kind of tube can you see?

 

[vintagelove]

Nice!!!

 

[MicMaven]

Either we need utmost transparency from the latest technology and vintage gear is high distortion garbage from the dark ages or vintage gears can somehow capture something magical that is definitely there

Roger all points. I suppose it sort, almost, kinda matters what we focus on and intend to accomplish. If we are trying to produce a vintage tone or vibe, then we may want to use equipment with inherent vintage distortion. If we are recording a vintage vibe, then we may want pure, transparent and accurate recording equipment. Perhaps we want to record with vintage gear to enhance the vintage vibe we are creating with our instruments. Perhaps there is an analogy to the common man's notion that electric guitar distortion pedals make a certain type of distortion sound we like to play ... and then we amplify it with a clean and purportedly transparent amplifier, and continuing the play, we then want to record it all accurately with transparent and accurate recording gear. Perhaps it matters where we add the vintage vibe ... perhaps not. So I agree, old gear is what it is, and does what it does, and was once state of the art. We can use it to record a vintage vibe, or not. Um ... ahem ... I think. Just joining in, so I will crawl back under my rock, now. . "Anonymous" ;-)

 

[TillM]

This is VF14k from Telefunken. My friend just tear down and this tube cost $750! What kind of tube can you see? View attachment 102763

Seams like a 408a or 407a.
I would say its a 408a.

@tomas.borgstrom amazing work ! Thanks for sharing.

 

[tomas.borgstrom]

Thank you so much for the test and for sharing your findings. Very informative

In this age of such scarcity of VF14 tubes, how did you manage to have 8 of them available for testing?

I own one U47 and I have a spare VF14. I repair microphones so I have four in my shop, two of them with spare VF14.

 

[tomas.borgstrom]

Seams like a 408a or 407a.
I would say its a 408a.

@tomas.borgstrom amazing work ! Thanks for sharing.

The text looks like Western electric

 

[tomas.borgstrom]

This is VF14k from Telefunken. My friend just tear down and this tube cost $750! What kind of tube can you see?

Do you have pictures from other angles?

 

[kingkorg]

@tomas.borgstrom , do you have a rough SPL figure of the level you tested this at? If you have a spl meter maybe you can give me spl at 1k? Also distance?

I have a mic with EF14, i'd like to replicate the test.

 

[rogs]

Fascinating thread -- This enthusiasm for tube (valve) equipment comes as a bit of a shock to those of us old enough to remember having to work with the horrible hot, unreliable, smelly things when they were still found in equipment we were obliged to keep going, commercially....
I was pleased to see the back of the nasty things!
But - like steam engines, vintage cars, old clocks, etc - there will always be those who enjoy working with 'old tech' as it were.
Fascinating to read about the love and attention still being lavished on these old relics....

 

[Tubetec]

Has anyone opened a VF14 and can share pictures ?
There were lots of SQ wire ended versions of regular tubes made for specific military and industrial uses ,

The tech the VF14 is based on came about in the years before WW2 ,
I wonder if theres a Russian equvalent of the VF14 around
Heres an Oktava MKL-101 mic that looks simliar to a U47 ,
It appears to have a regulated heater on the modern built psu.


All this fuss about trying to recreate the magic sparkle of the U47 with DSP or some kind of analog sidechain ,its all away with the fairies ,why bother ,
Just select a microphonic tube deliberately , do the mic sine wave test and see how the time smear looks .
If your not happy , subject the tube to vibration and retest .

Sonic burst tests might be an interesting way to reveal the hungover clang of mic body, component and tube/capsule interactions .

 

[kingkorg]

Has anyone opened a VF14 and can share pictures ?
There were lots of SQ wire ended versions of regular tubes made for specific military and industrial uses ,

The tech the VF14 is based on came about in the years before WW2 ,
I wonder if theres a Russian equvalent of the VF14 around
Heres an Oktava MKL-101 mic that looks simliar to a U47 ,
It appears to have a regulated heater on the modern built psu.
View attachment 102771
View attachment 102772
All this fuss about trying to recreate the magic sparkle of the U47 with DSP or some kind of analog sidechain ,its all away with the fairies ,why bother ,
Just select a microphonic tube deliberately , do the mic sine wave test and see how the time smear looks .
If your not happy , subject the tube to vibration and retest .

Sonic burst tests might be an interesting way to reveal the hungover clang of mic body, component and tube/capsule interactions .

Well, injection test, THD and phase curves at different levels and we'll have most of it covered. It seems to me for the first time in history shared publicly. I can't think of any remaining empirically testable variable. Besides the obvious elephant in the room the inconsistent capsule, and the headbasket interaction.

 

[rock soderstrom]

Here a some designs of microphones for microphonic tubes - no need for a capsule. Soliloqueen, you are doomed!

 

[Tubetec]

Its like the holy grail was an infinately variable set of components and interactions that changes over time , no two examples the same ,
its a wild goose chase if ever there was one ,
Im purposefully trying to reduce the effects of microphonic resonances in my mics and pres as much as I can .
If I want a mic that rattles like an ould tin can I can just use my stock Tbone SCT 700 with a nasty Shuguang Dragon red label 12AX7 in it .