Why do people still build tube microphones?

Why do people still build tube microphones?

Is it just as simple as people believing tubes are better?
Tubes are easier to get right even if you don't understand what is going on.
A cathode biased triode plate out is forgiving.

I am trying to get people posting.

I think solid state can be better.

Tubes are easier to get right even if you don't understand what is going on.

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That is pretty much the reason to use tubes for my microphon builds.

A cathode biased triode plate out is forgiving.

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But a fixed bias arrangement of some sorts sounds better, with pentodes and to my ears at least.
And it is not difficult to achieve the right bias voltages that way, but you need a very, very clean bias supply.
It is not that difficult....
Max's MK7 is a great circuit, but not the only one, I like the neumann cmv5, but that is all pretty standard.

Is it just as simple as people believing tubes are better?

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Well, the km84 is my favorite mic...

My guess is that non-technical reasons dominate.

Gus said:

Is it just as simple as people believing tubes are better?

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I suspect that's a major part of it. Had a look at that link to Lucas Engineering you posted in Skylar's U47-body thread. Now I'm sure that LE design fine equipment, but that site really harps on Purity Of Tube Essence. I know that's marketese and not aimed at solderheads, but it's a good example of the cargo cult thinking that surrounds tubes these days.

A semi-technical reason might be that tube circuits make it easier to cheat power-wise. Nobody expects to run a tube mic on only P48, and external PSUs are common and accepted. For solid-state designs, on the other hand, I feel that people think that because SS circuitry exists that can be powered by P48 all SS mics should be powered by P48. This yields a power budget which makes it very hard to use, say, modern low-distortion op-amps as part of a mic head amp. I find myself falling in that trap from time to time.

JDB.
[tinkering with a SS head amp for a stereo LD mic, playing with charge amps vs more traditional FET inputs]

tube spectral distortion is often different than spectral FET distortion in similar type of circuitries, so tube sound is often different than FET sound. For this reason several sound engineers think that the tube mics are important. However, there are a lot of tubes and a lot of topologies so isn't possible to do an rigorous rule. Infact, I've designed a mic tube with peluso c12, a cinemag trasformer and a triode that sounded more fast and quiet than a lot of (famous) fet mics compared with it, for example. Its sound is however a "tube like sound" yet but isn't the typical vintage tube mic sound that many sound engineer know.
The recording studio that 've bought this tube mic from me says these things I've written about this my mic.
I think that the matter is that several sound engineers think that the tube sound is always those of the vintage tube mics and also, moreover, some electronic engineers think that a mic IC opamp based can sound much better than a tube mic only because they look ad THD value only, but the matter is more complex like seem. A tube circuit distortion can be however less audible than an IC opamp distortion, for example. Or,(as it's very often ) a tube circuit distortion can be more lovely to listen than an IC opamp distortion.

Infact, there are some modern Gefell tube mics, designed as modern items, that however many sound engineers do not change with other SS or vintage tube items.  
 

Some people think tubes are better some solid state. Everybody has diferent beliefs and interpretations. I come from a family that has a strong electrical engineering tradition. Therefore I look into every claim from a scientific point of view. However, in terms of sound recording what we are dealing with is hearing. It sounds good? Then why not? Even if it does not sound good, still why not? Sometimes we need to record things that does not sound good either. In discussions like that I always give this example. From a signal integrity point of view the fuzzbox is a terrible circuitry. But produces a great rock sound.

I recently completed a G9 valve pre.

On paper it isn't as "good" as a solid state mic-pre. It is quite a bit noisier and suffers from higher THD than just about everything modern in the world of mic-pres. However it sounds great. Really great in-fact.

The same applies to just about anything. Don't get bogged-down in the figures. If the technically inferior thingamyjigger sounds/looks/smells/feels better than the technically superior thingamyjigger in any given setting, go with it.

Music and recording music are artistic processes. Ok there's a lot of science and engineering going on behind it all, but at the end of the day, it's what something SOUNDS like that matters.

Also, microphones are tools. There is a right tool for every job. Likewise there's the right microphone for every job (to further add confusion, there's at least a million different ideas about what's "right", just about 1 idea per recording tech!). If the ideal microphone for a particular application happens to be valve based, then that's the one to use.

C

PS The short answer to "Why do people still build tube microphones?" is "Because they can, they want to, there's a market for them and who's to say they shouldn't anyway!"

Weelll,



  you can wrestle my Sela, u48, Phillips etc tube mics from my cold dead hand . . . . .



      There are plenty of great ss mics too, (CAlrecs esp.), but . . . .



    ANdyP

Why do people still build tube microphones?

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Do you mean why do manufacturers do it, or why do DIYers do it?

Two very different questions.

With tube microphones I tend to like fixed bias.

I just drew up a u67 type solid state circuit the other day after reading some u67 thread at Klaus's.  I don't understand what the big issue is to make a circuit that has the correction circuits a u67 has and it would easy to do with a tube microphone as well no special transformer needed.  It would not be a u67 but it might be closer with a real 67 capsule and grill than one might expect.

I have a nice external powered solid state circuit that I really like and I might not even build tube circuits any more because of it: however every part of it was thought about temp stability, input and output headroom and other things.  I would guess someone might think it was a tube circuit because of it's "sound".  Still thinking about what to do with this circuit.  Can I sell enough to make money and pay for liability insurance?

Once something plugs in the wall what do you need to do to protect yourself?  Even selling PCBs might be an issue.

I'm building a tube mic cause it's so much easier to find info about tube than solid state amps in internet. My second mic project might be solid state mic. Many of us like how the "tube distortion" works in a mix and makes things upfront. It's lot harder to achieve this kind of character in a solid state circuit though it's possible. Martin Kantola designed the Bruce Swedien No. 1 for about ten years IIRR.

A clean solid state circuit has it's uses also of course. Your circuit sounds interesting. Only U67 type circuit I've found schematic for is the U67 circuit. But of course I'm not suggesting for you to share it with us (seriously, I understand how giving away your work constantly for free has it's draw backs)

Marketing.  People who are not 100% in the know have certain opinions about tubes some true, some false, so why not stick a 12ax7 in there and say hey its a valve mic. will sound warm, blah, blah, blah.

OK Gus let me ask the reverse question.

You challenged me to experiment and learn about topology, what really goes into designing a mic when I started a thread about an M50 build. I've been through the wringer in my head due to limited time but did get to read some real good stuff, and I did get to play around a little bit.



The question is: What is it that gave the old stereo-tracked RCA Living Stereo recordings their 3D-ness and musicality?

I have a pair of modded MXL603S mics. I normally use a pair of Rane MS1B preamps with them and they do sound good. But I did a choir recording with them using my friends DW Fearn VT-2 and I was pleasantly surprised as my jaw hit the floor. All of the loveliness and musical depth I wanted to hear was there. The high end was smoother and less harsh-sounding and the bass was huge sounding. Yes I know these are all unscientific adjectives...

OK so I've found that I don't get the sound I like out of tube amps that are too "linear". The fixed bias stuff is the real deal. Negative feedback also is a real spoiler of that "sound" I think.

I dunno I'm still a newbie here, but your post struck a nerve.

I just want to say that in my case it's not just mics that make that difference. I will, eventually, finish the m50-like mics.

Let me also say this. I've recorded many vocalists, and once most of them hear my Sony C48 through my cheapo MS1B preamp, they don't want to use the U87. Now that C48 I believe is a very nice sounding large diaphragm FET. I know the U7 isn't like a nice tube U47 or anything but it still a popular mic. Just saying that Sony design may be worth checking out...

Gus whatever you make I would like to try!

Some capsules in valve mics used the B+ for polarization.  So the capsules would be different, too?

riggler said:

The question is: What is it that gave the old stereo-tracked RCA Living Stereo recordings their 3D-ness and musicality?

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Studio acoustics, mic placement, echo chambers, players/producer/sound engineer interaction, moderate processing. Tubes, transformers, class A are far down in the list.

OK so I've found that I don't get the sound I like out of tube amps that are too "linear".

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That's probably the answer to the original topic.

The fixed bias stuff is the real deal.

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This may be true for a power amp, but a class A preamp with quasi constant-current operation...come on!

Negative feedback also is a real spoiler of that "sound" I think.

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NFB reduces harmonic distortion. It is consistent with the fact that you like distortion.

Let me also say this. I've recorded many vocalists, and once most of them hear my Sony C48 through my cheapo MS1B preamp, they don't want to use the U87. Now that C48 I believe is a very nice sounding large diaphragm FET. I know the U7 isn't like a nice tube U47 or anything but it still a popular mic. Just saying that Sony design may be worth checking out...

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Sony capsules are significantly different than Neumann's. I would say 90% of the difference is in the capsule. Apparently, Sony mics manage to maintain their difference, whether they are tube or solid-state.

lernith said:

Some capsules in valve mics used the B+ for polarization.  So the capsules would be different, too?

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Some valve mics use standard capsules (40-60V bias) where bias is derived from B+.
Some mics have high bias capsules, which exhibit lower capacitance; these capsules are either very small (1/4" to 1/2") or larger (1/2 to 1") but with larger distance from the backplate and/or larger diaphragm tension.
In the case of smaller diaphragm, the higher bias compensates for the lack of sensitivity, in the case of larger diaphragms, the use of higher voltage allows the optimisation of certain characteristics, such as VLF sensitivity.

I feel that people think that because SS circuitry exists that can be powered by P48 all SS mics should be powered by P48. This yields a power budget which makes it very hard to use, say, modern low-distortion op-amps as part of a mic head amp. I find myself falling in that trap from time to time.

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Exactly. I find myself compromising significantly to accomodate the weak phantom current capability.
Makes me want to design some SS mics with external supplies. An attenuator switch for high spl would no longer be needed!

Les
L M Watts Technology

Off the top of my head, I like the sound of valve distortion (in good designs), and also there are benefits to having a large power supply which is almost always necessary.

It's a bit like also saying, do we need transformers in mics? The answer is "no" almost always as we can get good CMRR with electronically-balanced, decent headroom, low distortion, and we often don't need galvanic isolation....... But I think transformers can often have a beneficial effect on the overall tone.

Interesting topic. I don't buy the distortion argument in this case. At moderate volumes a good tube mic has distortion products far below threshold of audibility.
If distortion would be the answer then a tube mic would sound "tube mic" only with 110-120dB SPL sources when THD reaches 1%. My experience with my own construction is that the sound is not particularly "warm" perhaps because I use a neutral transformer.

I'm still waiting for the right explanation. Oh well, perhaps not, I just live with the fact that I don't understand.

You can select and adjust a solid state circuit and select parts to sound more like a tube you can adjust the "woolyness" distortion.  With an external supply you can do more with less compromises.  I looked at my notebook and I started on the solid state design I like in 2008.   I tried different transformers gain stages and other tunings.  If I told you what it is, I think some "purists" would dismiss it without even trying it

One can make a tube sound very clean.

I like what abbey road d enfer posted      "Studio acoustics, mic placement, echo chambers, players/producer/sound engineer interaction, moderate processing. Tubes, transformers, class A are far down in the list".

Why will people have no problem with a power supply for a tube microphone but not want a external power supply solid state microphone?

Gus,

I think that tube circuits have a higher perceived value compared to solid-state.
Consumers are typically not willing to pay more than what they think a product is worth.
Because an external power supply will increase the end-user cost on a commercial microphone, perhaps the solid-state mic with external PS demands a price beyond what consumers will pay.


Personally, I would have no problems with an external power supply for such a mic if it sounds good.
For me it all comes down to performance/sound.

If an externally-powered SS mic were on the market, I would consider it if:
-I had an opportunity to use it before purchase
-it were reviewed favorably by someone I trust (probably word-of-mouth)
-it were made by a company I trust
-it was relatively cheap
-or some combination of the above


After having spoken with you a few times, Gus, I take your designs seriously.
You have a reputation for designing great stuff, so I am confident that (even without having heard it) your SS mic is awesome.

Now you just need to work out the legal liability issues, and sell some mics/pcbs/whatever.