Microphonics in U47 Question

[Seattlesound12]

Hi all,
I have attached a dry audio recording of my U47 making some kind of microphonic sound post being sung into plus a very light flick of the body where you can really hear it. I am curious if this normal? A sign my tube is at the end of life? Could it be a component or mounting issue? And lastly, if addressable, do folks have anyone they can recommend to service it? I sent it originally to Vintage King but they didn't catch this much less address it so I am in search of other options for servicing my mics. Thanks!

Here is a link to the wav file as the upload here didn't seem to work:


-Seth

 

[rock soderstrom]

Hi Seth, wav file doesn't work.

For starters, check this thread.

https://groupdiy.com/threads/microphonics-in-vf14-and-u47.82644/

Cheers

 

[Seattlesound12]

I updated the wav to a link. I read that thread - the main takeaway I found was that dampeners matter. I have one in place but not sure that's the culprit.

 

[rock soderstrom]

I updated the wav to a link.

Works - the ping sounds like a good G

 

[kingkorg]

I updated the wav to a link. I read that thread - the main takeaway I found was that dampeners matter. I have one in place but not sure that's the culprit.

I have been ranting about this for years even though many claim u47 is not microphonic. IMHO this behavior is expected, and you have a perfectly working u47.

You can also check if the part of microphonics comes from the grille, just hold the grille tight with one hand while you "ping" the body. Hear if there's any difference.

 

[Seattlesound12]

I have been ranting about this for years even though many claim u47 is not microphonic. IMHO this behavior is expected, and you have a perfectly working u47.

You can also check if the part of microphonics comes from the grille, just hold the grille tight with one hand while you "ping" the body. Hear if there's any difference.

So this doesn't impact recording in your opinion? Feels odd to have a tone just hanging there. I have an M49 with none of these effects also vintage. Is this unique to U47s? I'll try the grille thing.

 

[Ericbazaar]

Hi,

try to replace the black Tube bumper by a softer one, these bumpers drying out and hardening over the time.

best
Andreas

 

[kingkorg]

So this doesn't impact recording in your opinion? Feels odd to have a tone just hanging there. I have an M49 with none of these effects also vintage. Is this unique to U47s? I'll try the grille thing.

Well my take on it is that the microphonics are the part of the sound people tend to overlook. If you take it away you loose part of the vibe. M47 is much smaller, has tighter body, also has way different type of headbasket that shouldn't ring, and it has less internal reflections. The tube in m49 is for sure less microphonic. The myth surrounding the u47 is that it's somehow immaculate, flawless, piece of gear. My take is that it's far from perfect, and all those quirks add up to it's unique sound.

People selling, hoarding, mystifying, glorifying u47 parts like tubes, transformers, capacitors make money from it. On the other hand, if you take my approach, there's not much money to be made by selling microphonic, less than ideal parts u47 is originally made out of. This is not to bash u47, or say it's bad in any way, it's just to say it's a sum of all the parts, and those parts have their own quirks that don't necessarily scream quality by today's standards. This goes for vintage capsules as well.

 

[Seattlesound12]

Well my take on it is that the microphonics are the part of the sound people tend to overlook. If you take it away you loose part of the vibe. M47 is much smaller, has tighter body, also has way different type of headbasket that shouldn't ring, and it has less internal reflections. The tube in m49 is for sure less microphonic. The myth surrounding the u47 is that it's somehow immaculate, flawless, piece of gear. My take is that it's far from perfect, and all those quirks add up to it's unique sound.

People selling, hoarding, mystifying, glorifying u47 parts like tubes, transformers, capacitors make money from it. On the other hand, if you take my approach, there's not much money to be made by selling microphonic, less than ideal parts u47 is originally made out of. This is not to bash u47, or say it's bad in any way, it's just to say it's a sum of all the parts, and those parts have their own quirks that don't necessarily scream quality by today's standards. This goes for vintage capsules as well.

I just don't think that a 4-6 second harmonic or microphonic tone after everything sung is usable in recording or would have ever been usable on any take from a serious group. It would be very clearly heard in any quiet recording and I think most engineers would have quickly just put these mics in the trash bin and picked another mic. While I am always down for that 'vintage' sound this feels like something is broken. Will try some of the dampening approaches. I held the grill and don't notice any real change.

 

[Seattlesound12]

Hi,

try to replace the black Tube bumper by a softer one, these bumpers drying out and hardening over the time.

best
Andreas

Will try some of this out with another dampener.

 

[rock soderstrom]

I just don't think that a 4-6 second harmonic or microphonic tone after everything sung is usable in recording or would have ever been usable on any take from a serious group. It would be very clearly heard in any quiet recording and I think most engineers would have quickly just put these mics in the trash bin and picked another mic. While I am always down for that 'vintage' sound this feels like something is broken. Will try some of the dampening approaches. I held the grill and don't notice any real change.

I also think that above a certain level, microphony can cause too many problems and then you have to react. I already had this with one of my (non U47) builds. It can have various causes, from mechanical excitation of the body/basket to internal reflections to microphonics of the tube, anything is possible. I had big problems with EF12k tubes. Out of 6, one was reasonable usable...

My first advice would normally be to change the tube and see what happens. This is not so easy with an original VF14. Do you have access to a spare tube for testing?

 

[kingkorg]

This is not so easy with an original VF14

One of those Phædrus solid state replacements would be ideal for the job.

 

[Recording Engineer]

One of those Phædrus solid state replacements would be ideal for the job.

Have one sitting right here and sounds good too; although cleaner and leaner.

 

[tomas.borgstrom]

I just don't think that a 4-6 second harmonic or microphonic tone after everything sung is usable in recording or would have ever been usable on any take from a serious group. It would be very clearly heard in any quiet recording and I think most engineers would have quickly just put these mics in the trash bin and picked another mic. While I am always down for that 'vintage' sound this feels like something is broken. Will try some of the dampening approaches. I held the grill and don't notice any real change.

I don't think the engineers at Decca, Capitol, Abbey Road etc would accept such artefacts but they had the option to buy a new tube. Of the measurements I made only two tubes had the "M" mark from Neumann. One of them was microphonic, the other one was much better and I personally think that a U47 with the none microphonic tube sounds clearly better.

There are other tube alternatives but not many. Pheadrus sounds fine but the dynamic response sounds solid state.

I recently serviced a CMV3. RE084 (even some RE084k I tried) is by far the most microphonic tube I've ever heard in a microphone. I wonder how many Neumann had to reject.

 

[Electrobumps]

I don't think the engineers at Decca, Capitol, Abbey Road etc would accept such artefacts but they had the option to buy a new tube. Of the measurements I made only two tubes had the "M" mark from Neumann. One of them was microphonic, the other one was much better and I personally think that a U47 with the none microphonic tube sounds clearly better.

As soon as Decca had the technology they removed all the valves from their mics and put transistors in. So that is always an option!

 

[MagnetoSound]

As soon as Decca had the technology they removed all the valves from their mics and put transistors in. So that is always an option!

They also turned down The Beatles

 

[Drea]

You have always a choice. Nobody can help you with that. Personally I think that if you don’t like it put it in the glass display case and use a new. But All those noises makes it real. Besides tape noise is no longer in the pad.