Tube Mics, vs FET Mics

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Absolutepower

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I have a few questions about this. In your guy's opinion, which if these two categories do you find better sounding or more useful on vocals? OR, are they really equally useful and some just sound better on different people's voices? This is assuming you could have/afford any mic you chose in those two categories.
Last of all, what would you say are the real differences between these two categories in terms of capturing voice? Does one generally have more detail or what?
I ask this because I'm new to the world of mics, and there is a ton of hype around tube mics which seem to generally a lot more expensive, but it seems that the FET ones can be used very successfully as well. I read somewhere that Led Zeppelin vocals were done with a U67 fet. Can anyone confirm that?
 
I think it's very difficult to make a categorically valid statement on the topic.
 
If you get Tape Op magazine...in the current issue, there is an interview with David Bock, who builds some high-end mics under his Bock Audio biz.
He also worked with and design mics for Soundelux.
He talks about tube mics and FET mics in the article.

One thing he does mention is that he feels a proper FET mic should not be phantom powered...rather that it should have it's own power supply.
He felt that designing FET mics to run via phantom power was a trade-off but obviously less expensive.
Mind you...he's talking about $3k-$5k mics. :)

I use both tube and FET...and each can sound quite good...of course, it depends on the individual mic build quality and your intended application.
 
Led Zeppelin is my favorite band of all time, but I think the recorded vocals are crap. Mind you it was 1972 and most vocals sounded that way.

I have never used a tube mic and I'm curious what users would say. Most use a good tube pre, so would 2 tubes in front of vocals get the hot modern voice signal or would it actually be a detriment?
 
miroslav said:
One thing he does mention is that he feels a proper FET mic should not be phantom powered...rather that it should have it's own power supply.
Click to expand...

I don't really see an issue there. There are two separate requirements in a microphone; a high polarization voltage for the capsule and a bit of current for the amplifier. There isn't a need for more than 4mA for the amplifier (less if there is an output transformer). Nominally, that would leave only 34V for the capsule, but for 40 years now FET mics have had internal step-up circuits if they so desired a 60V (or higher) polarization (see AKG for example). Since the current required by the capsule is essentially zero, it's quite easy to design an adequate filter to prevent supply noise from leaking into the capsule signal.

There are plenty of FET circuits that operate with gobs of headroom (and note that increasing supply from 60V to 120V only increases headroom 6dB), and a transformerless circuit should be lower distortion than a transformer circuit (but we love them, don't we?). So where's the beef?

Now, on the lowest end, there are very simple FET circuits that are happy dribbling 35V to the capsule, and you see that in poor SNR specs on large diaphragm mics that should normally be much quieter . . .
 
miroslav said:
If you get Tape Op magazine...in the current issue, there is an interview with David Bock, who builds some high-end mics under his Bock Audio biz.
He also worked with and design mics for Soundelux.
He talks about tube mics and FET mics in the article.

One thing he does mention is that he feels a proper FET mic should not be phantom powered...rather that it should have it's own power supply.
He felt that designing FET mics to run via phantom power was a trade-off but obviously less expensive.
Mind you...he's talking about $3k-$5k mics. :)

I use both tube and FET...and each can sound quite good...of course, it depends on the individual mic build quality and your intended application.
Click to expand...

Hey Miro.....Is that the July/Aug. issue?
I'll be damned if I didn't leave it out at the studio and now I can't find it. :mad:
I think someone walked off with it before I could read it. :(
Oh well I'll find it on line I guess.





:cool:
 
mshilarious said:
I don't really see an issue there.
Click to expand...

He doesn't get into the nitty-gritty of the electronic reasons why in the article (nor do I personally care :) )...but Tape Op has a "Letters" section, so you might toss him some of your points and see how he responds....???

I have a few FET mics, and they sound really sweet...though they ain't any of the cheap, $99 stuff that's all over the place these days.
I'm sure there are a few ways to do those designs...and of course, the components will matter too.



moresound said:
Hey Miro.....Is that the July/Aug. issue?
I'll be damned if I didn't leave it out at the studio and now I can't find
Click to expand...

Yeah...that's one: http://www.tapeop.com/index.php
 
miroslav said:
He doesn't get into the nitty-gritty of the electronic reasons why in the article (nor do I personally care :) )...but Tape Op has a "Letters" section, so you might toss him some of your points and see how he responds....???

I have a few FET mics, and they sound really sweet...though they ain't any of the cheap, $99 stuff that's all over the place these days.
I'm sure there are a few ways to do those designs...and of course, the components will matter too.





Yeah...that's one: http://www.tapeop.com/index.php
Click to expand...

Thanks Miro! :D
That' ll teach me to leave good reading material just hanging around.





:cool:
 
Nah I ain't saying nuthin he doesn't already know. Just curious why everybody seems to want more current these days . . . P12 and low current is the future, along with switching supplies, whether they are in the mic or the interface, they are there. Maybe not in the handful of big pro studios that will survive . . . but if this wasn't a problem for the early Neumann, AKG, etc. FET mics that everbody likes . . .
 
mshilarious said:
Nah I ain't saying nuthin he doesn't already know. Just curious why everybody seems to want more current these days . . ..
Click to expand...

This was his more detailed comment:

The transistor mics I didn't like as much. That's before I'd studied enough design to understand why.

There are piles of problems. First of all, FET mics should never have been standardized with phantom power. They should have had their own power supplies like tube mics do. That would have been a huge improvement right there. They're so finicky that they need to be specially treated. There is no simple FET circuit that works perfectly - not like a tube where you can throw a triode on a good capsule and you've got a halfway decent mic.
Click to expand...

He doesn't go much deeper than that in the article on FETs.

*shrug* :)

The way I'm reading it...he doesn't seem (?) to be saying FETs need more current...it sounds more like he's saying each FET design would be improved if it had its own dedicated and specifically designed power supply...like tube mics do.

Is that how you read it...?
 
Having just done quite a bit of research to upgrade to a tube from a KSM32, I can share a couple things I learned along the way. First of all, there is no inherent improvement in sound quality between a good FET and a good tube -- they can both be wonderful. But you can make a few determinations of tube quality by examining price. Under a certain price point, say around $1,000 or so, you can probably get a better performing FET. (But there are always exceptions -- Taylor Swift uses an Avantone CV-12, which offers exceptional value.) Some manufacturers make a tube design in this lower category with pretty dismal results.

Above $1,000 (or so), tubes start closing the gap on good FET's, and one or two notable exceptions surpass FET's until you get to the $3-4,000 range.

I think well-designed tubes have some slight advantages over high-end FET's, but this is also dependent upon the sound you're going for. On voice, tubes tend to have a slightly warmer, silkier response through transients, and are a bit more forgiving. Because of this, tubes are not good choices when quick response (such as for a trumpet, etc.) are the goal. A good tube on an acoustic guitar gives amazing results.

If your vocal goal is a Frank Sinatra or Judy Garland sound, then you're looking for a good tube. (These singers used Neumann u47s, but that classic sound can be replicated with a good tube.) If you're recording rap, or screaming, then a tube would be a waste.

I'm no expert, of course, but I was advised by a recording engineer that in the $1,200 to $2,000 price range, the best value in an FET is the Blue Kiwi. The best value in a tube (coming out on top in a couple of high-value shootouts) is the MikTek CV4.

Hope this helps.

-Bruce
 
"There is no simple FET circuit that works well."

I would tend to agree, but the corollary to that is that it's really cheap to throw more transistors at a problem to fix it. In contrast, there are some limitations to tube mics that can't effectly be solved because nobody is putting more than a twin triode in a microphone. Many people perceive those limitations as a benefit, so there isn't much demand for a solution anyway.

Hmm, I just did a FET guitar preamp design as a tube amp topology would be (rather than as most solid state amps are); that is a surprisingly rare concept. It could translate to mics as well, but I don't think there is really any point.
 
mshilarious said:
Hmm, I just did a FET guitar preamp design as a tube amp topology would be (rather than as most solid state amps are); that is a surprisingly rare concept. It could translate to mics as well, but I don't think there is really any point.
Click to expand...

You're right on track, though. Several mic gurus that I talk to indicate that its really about topology. With the right design a FET circuit can be just as sweet sounding as tubes.
 
One of my "best" LD microphone builds is an external powered solid state one. It took some time to get to the circuit I like. I am also working on another solid state circuit to emulate what tubes add to a microphone build.

Fenders 80's? solid state Harvard amp used jfets in a clever tube like circuit for the preamp part of the amp.
 
Gus said:
One of my "best" LD microphone builds is an external powered solid state one. It took some time to get to the circuit I like. I am also working on another solid state circuit to emulate what tubes add to a microphone build.

Fenders 80's? solid state Harvard amp used jfets in a clever tube like circuit for the preamp part of the amp.
Click to expand...

Have you looked at the circuit design of the MXL V6? This microphone does just that.





:cool:
 
Wow thank you guys, got a lot of awesome replies in this thread, good discussion.
 
Especially on vocals, most fets could use some tube distortion from a tube preamp, or being colored some more by, lets say, a distressor. Some boring mics could get exciting.

I do like the combo fet mic and tube preamp; with more than one channel, you have many flavors to choose from. I like this better than a combo tube mic / solid state pre, for a matter of versatility.

Then stacking two tubes is usually too much for my liking, I feel like I'm losing the true character of the mic.
 
surprised nobody has chimed in here about the led zep thing:

most, if not all of the led zep vocals were recorded on a Shure SM7.

and I agree, I don't love the tone in some of the albums. But then I don't love the sm7 when you engage the mid boost and low rolloff switches. Yet people still record with it that way all the bloody time.

the vocals on the first album sound great, I'm not sure if that was an sm7, but either way, teh engineering was brilliant on that album.

anyway, back to your thread's actual topic...
 
If I'm not mistaken (and I very well could be), I remember reading somewhere that on Led Zeppelin IV the studio had Robert Plant in the control room on a U47 while the tracks where recorded. Maybe those weren't the tracks they kept?

I know Bonham had 2 U47's as overheads on the kit.

(sorry for the off-topic)
 
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