Why do people still build tube microphones?

[rodabod]

Regarding the distortion/colouration argument, I think I feel similarly about guitar amps; valves just sound more pleasing in general, even when played "clean".

 

[desol]

Given the fact that there are mics out there that are almost impossible to overload and have decent output, P48 seems to be sufficient. Take for instance a Neumann TLM103. Self noise is very very low at 7 dB-A. Its sensitivity is 23 mV/Pa (about -33 dB), which IMHO is about as hot as is sensible, and its max SPL is rated at 138 dB. In practice, I have yet to find a source that overloads the mic itself. Current draw is about 3 mA. It's not my favorite mic, but it proves that you can fulfil just about any technical requirement within the limits of P48.

This is a perfect example of the issue, with numbers that look really good and a microphone that's far from great sounding. Technical requirements are one thing, sound is another it seems. Unfortunately we sometimes have to balance the two.

Martin

Exactly. How many designers are actually listening, first and foremost? And what are they settling for?
It seems clear, that you can't design something that is supposed to 'sound' good...without 'being able' to listen to it.

ie: What sounds good to a clever designer, may sound like ass to Neil Dorfsman. I'm thinking the best mic designers peer review their designs with the best listeners...and adjust accordingly.

 

[Rossi]

That appears convincing, yet all great classic mics were designed without input from reputable recording engineers. In fact, they were invented before music recording became a big business. Hence they were designed for broadcast use.

I'm pretty sure, though, that manufacturers do ask engineers for their opinion these days. And maybe that's the problem. You ask 10 engineers, you get 11 opinions and then you average between those. Sure enough, what you get is an average microphone.

 

[tv]

Hence they were designed for broadcast use.

But hey, who -wouldn't- want a beyond-mesmerizing narrator voice? If you think twice..

 

[skipwave]

You ask 10 engineers, you get 11 opinions and then you average between those. Sure enough, what you get is an average microphone.

That's a great line. I'm tempted to put it in my sig.

We must consider that a Swiss-army-knife does-it-all-well microphone cannot be exceptional on any one source when judged against microphones which where more or less purpose-designed and purpose-built for that very single application/source.

Microphones intended for vocalists are a great example, since voices vary widely, but the averaged desirable characteristics are few and easily identified. I saw an advert for the new Neumann tlm102 that said "A slight bump at 6Khz makes vocals shimmer" (or some such generalization).

What does any of this have to do with hollow vs. sand state? Damned if I know. I've put tube circuits in two lowly microphones and thought they classed-up those up quite a bit. Vocals were extremely harsh pre-tube-mod. Now they are painless and pleasing. Worth the weight-y power supply for me.

 

[lassoharp]

Hence they were designed for broadcast use.

But hey, who -wouldn't- want a beyond-mesmerizing narrator voice? If you think twice..

That's a cool point and I do think that clarity and a certain amount of robustness in the bass response was probably a quality of merit for mic designers and console preamp designers in the broadcast market. I must say though that I think the late great John Facenda would've sounded just as commanding through a beat up EV lollipop as a U47 - at least through your 4 inch TV speakers!

http://www.broadcastpioneers.com/facenda-wip.html

I think the swiss-army-knife comment by Rossi must be extended to include economics/marketability.  Remember when AKG came out with with all those very mediocre mics to seemingly fill the pricepoint between the C-1000 and the 414?  One of those being the somewhat forgettable Solid-Tube.

On that note I'm going to amend the original question with:  (given the # of other tube choices) Why do modern designers choose a 12ax7 for a tube mic? 

I've never built a tube mic circuit but if the ax7 has the same issues in that context as they do in a mic preamp - namely the tendency to roll off the highs and sound grainy - it makes me wonder if the designers are using perceived commonality as a deciding factor there. But I haven't heard them all - maybe there is a stellar sounding tube mic that uses a 12ax7. Any opinions there?

 

[zebra50]

Why do modern designers choose a 12ax7 for a tube mic? 

Cheap, and still in production.

 

[Martin B. Kantola]

Well to be fair, we don't know what the K103 capsule sounds like with a different circuit as it is only used in the TLM103.

True, but I can almost bet the capsule isn't the only limitation...

Basically, we have to think about what we really want. For a long time the direction was clear: People wanted transparent microphones. Ideally, the recording should sound like what you hear with your naked ears.

Exactly but totally impossible to achieve and not even desirable as been pointed out by greater men You are so right that we should carefully ask ourselves what we want. In my microphones, I want to hear that engaging quality you speak so well about. It doesn't seem to be in conflict with any other property really, and it's not simply distortion or a peak in the frequency response either. Certainly not some magic sauce ;-)

Might say that I'm more interested in the impact of an experience than what the ear is hearing. For some reason (and the U47 is a good example) an engaging microphone can work for in surprisingly many applications besides vocals. While the people who designed the classic microphones were engineers, they certainly used their ears a lot. Because that's all they had for quite some time. The human hearing and the human voice is a reference that can probably not be ignored, it's built into all of us.

Martin

 

[tv]

Hence they were designed for broadcast use.

But hey, who -wouldn't- want a beyond-mesmerizing narrator voice? If you think twice..

That's a cool point and I do think that clarity and a certain amount of robustness in the bass response was probably a quality of merit for mic designers and console preamp designers in the broadcast market. I must say though that I think the late great John Facenda would've sounded just as commanding through a beat up EV lollipop as a U47 - at least through your 4 inch TV speakers!
....

I know some guys who did lots of synchro, also some were/are radio-techs etc. So although I'm music oriented, I'm familiar with their standpoint - i.e. importance of voice narration (deep but not boomy, "larger than life", "bloomy" ... ). I witnessed some pretty obsessive moments regarding narration recording in "pre-plugins" era as well.

So I'm not exactly sold on "true to life" story. In this area, everybody I met wanted candy..

http://www.youtube.com/watch?v=aMICD3aMZpw

 

[Rossi]

Exactly but totally impossible to achieve and not even desirable as been pointed out by greater men You are so right that we should carefully ask ourselves what we want. In my microphones, I want to hear that engaging quality you speak so well about. It doesn't seem to be in conflict with any other property really, and it's not simply distortion or a peak in the frequency response either. Certainly not some magic sauce ;-)

That's a point that's often misunderstood by "the small diaphragm police". They often argue that a recording should be as clean and linear as possible, and if you really want some kind of flavor, you could add that later on. Like sauce on a schnitzel. However, there is simply no way to add some U47-flavor. Also, it isn't just a flavor, it is a perspective. A microphone represents a certain way of listening. A U47 has a kind of mojo that you can't just add after the fact. It inspires you (the performer) the very moment you use it. There is no retroactive inspiration plug-in.

Might say that I'm more interested in the impact of an experience than what the ear is hearing. For some reason (and the U47 is a good example) an engaging microphone can work for in surprisingly many applications besides vocals. While the people who designed the classic microphones were engineers, they certainly used their ears a lot. Because that's all they had for quite some time. The human hearing and the human voice is a reference that can probably not be ignored, it's built into all of us.

I'm sure they used their ears, but they also invented and developed measuring devices and methods (Neumann used to build frequency plotters ("Pegelschreiber") and measurement microphones back in the day). In that sense, little has changed in development. What has changed is the market. In the 50s and early 60s, there weren't many companies producing studio grade microphones. The market was small and most microphones were bought by broadcast firms. In Germany and many other European countries, radio and TV were state-operated only (In Germany that changed only in the 1980s).

In a way, money didn't matter as much as it does today. When you build a TV or radio station (and state-operated ones tend to be fairly big) and raise buildings, buy all inventory and have dozens or even hundreds of people on payroll, a set of microphones, even expensive ones, isn't that much compared to the total cost. And since there was very little competition, people had to buy the few mics that were available at the price they cost. There was no urgent need for manufacturers to meet certain price points. Technical brilliance was more important than saving a few bucks.

There simply was no alternative to a U47, when it came out. And even if there had been a cheaper alternative, a state-operated radio station would still have bought the more expensive mic, if it was technically better and/or more usable. When the U47 came out, it was a landmark. It was much lower noise compared to anything that came before (and even a lot of mics 50 years later!). Plus you could switch between cardioid and omni, which was a brand new feature then. It also sounded more brilliant than any other mic available then.

Today mics have to make a certain price point in order to beat the competition. In order to survive, mic companies have to pay a lot of attention to the market and react to its needs. Average sells better than ultimate.

 

[desol]

That appears convincing, yet all great classic mics were designed without input from reputable recording engineers. In fact, they were invented before music recording became a big business. Hence they were designed for broadcast use.

I'm pretty sure, though, that manufacturers do ask engineers for their opinion these days. And maybe that's the problem. You ask 10 engineers, you get 11 opinions and then you average between those. Sure enough, what you get is an average microphone.

My point about listening wasn't really about who, but what...and the concept didn't start with me. If i can find the thread at PSW, in the mic lab, i'll post it. Also, Neil Dorfsman and other engineers of his calibre...are not just average engineers, they're the world's best. But that's all besides the point. Regardless, I'm sure Neumann didn't just stumble across a multitude of consistenly great sounding products by accident. The high calibre of products specified by the broadcast industry or the scientific community at the time, would be consistent with the quality produced, hence again....critical listening and measuring. In broadcast, a mic has to do an excellent job of voice reproduction...no?

 

[pstamler]

In broadcast, a mic has to do an excellent job of voice reproduction...no?

Yes and no. In European broadcasting, from the 1940s through about the 1970s, live (or live-on-tape) classical music concerts were a big part of the picture. When the U 47 arrived one of its big attractions was that it did a better job on an orchestra in a hall than anything on the market.

Peace,
Paul

 

[abechap024]

I was 14, I played electric guitar. I practiced through a transistor Peavey PA. One day rummaging through an old CB repair shop I found a old Voice of Music powered Extension speaker. I plugged in my guitar and the sounds comming from the box blew my fragile young mind. I didn't know all the right lingo,it just sounded magical. I'm a fan
I want to Only own Tube Microphones.
Tube everything for that matter - if I could.
.

 

[fazer]

rossi you hit the nail and maybe someone else in an earlier post as well.    When you set up a U47 67 or 249 Elam251 etc.  It's as much to do with how it inspires the singer to sing that makes the engineer get the sound they get.  When the earphones go on I'm always hoping the performer is inspired to play or sing.    It makes your job easier as an engineer.    Its more than just bright cutting sound.  Its the air you hear around the sound.  It lives in a 3D space.  It happens more so with a classic Neuman Tube mic or C12.

However a large capsule mic will also point out the room modes in a space that's to small, or to live or just to dead and not not neutral.    In that situation a small capsule is more direct and seems to not show the poor room acoustics as much.  I like KM54's for that. 

 

[Rossi]

Large diaphragm cardioids are often almost omni at low frequencies, so they do pick up more room rumble. SD mics tend to have a tighter cardioid pattern. However, the "loose" LD cardioid is nice for the performer. The almost-omni pattern at low frequencies lessens the proximity effect and makes the low end much more controllabe for the singer.

But we're getting off topic. I think it should be possible to build a killer vocal mic using solid state devices, and I think P48 ought to do for powering.

 

[Gus]

P48 limits you.  You need to design something to work on all phantom power supply current rating and voltage.  There are other things about P48 that limit you as well.  One can build a good sounding solid state P48 powered one but it might not be the "best".

 

[ppa]

yes, infact I've intention to develop a SS mic based on U-47 mic body with PSU.

 

[Rossi]

P48 limits you.  You need to design something to work on all phantom power supply current rating and voltage.  There are other things about P48 that limit you as well.  One can build a good sounding solid state P48 powered one but it might not be the "best".

It's true, you can't expect all P48 supplies to be capable of 10 mA (although they should be!), and some don't even supply a correct voltage, although it the specification already allows for +/-4V. You have to make a decision on what's still okay and what's not. There are some boxes whose P48 is plain wrong. There is a reasonable margin of sub-specification performance you better allow for, but at some point you have to say: no, I won't support his crappy excuse for P48 supply.

It's probably reasonable to stay below 5 mA. Yes, for some designs you may wish for more than that. But I think you can do just about anything with 5 mA. For proper polarization you need a DC converter anyway, so the actual supply voltage is not that important. It's also wise implement some kind of supply filtering and stabilization.

An external supply does have its advantages, technically speaking. But recording is not just listening, it is also creativity and action. An external, non-standard supply does get in the way of the creativity/action-part. At least if you own a number of microphones and pick them for various tasks. It is great to be able to just plug in a different microphone and fire it with P48.

I suppose there is a small market for solid state mics with external supplies, but there will never be a big market.

 

[ppa]

I suppose there is a small market for solid state mics with external supplies, but there will never be a big market.

there are sound engineers who know that's possible having different sound look and performances with external PSU, so there is a market for these mics.

 

[hop.sing]

I suppose there is a small market for solid state mics with external supplies, but there will never be a big market.

there are sound engineers who know that's possible having different sound look and performances with external PSU, so there is a market for these mics.

There is this guy Dieter Schöpf who builds non phantom powered solid state mics: http://www.sommercable.com/cardinal/2/index.html
We have one of his Tube mics at our Studio and that is certainly a world class microphone (MBHO capsule and an Andreas Grosser designed circuit with an ef12 tube).
Since he is working with A. Grosser, I have the feeling his solid state design might be the one Grosser uses in his VF14 replacement circuit which is supposed to sound very much like the tube and runs on high voltages.