Turn Tube Mic Upside Down= Is there real value?

[AcousticDreams]

I did a little research just now to find out if there really are valid reasons for turning a tube mic upside down as my new BU67 should be arriving in a few days.

**Sweetwater
Vintage tube microphones were often positioned “upside down” so that rising heat from the tube wouldn’t affect or damage the fragile diaphragm.

Another reason is that with the mic hanging above the vocalist from a boom stand, there’s room for a music stand in front of the vocalist. Plus, there’s less chance the vocalist will hit the mic stand with a hand, foot, or other flailing appendage in the heat of a passionate performance.

**Recording Hacks disputes this saying:

"The problem is, this explanation doesn’t really make any sense. The capsule deck in every tube mic I’ve seen is sealed off from the chamber where the tube is. Plus, the headbasket is vented to the outside air. Does the capsule really get any warmer due to tube heat?"

" The electrolytic capacitors found in most audio gear have a useful life span that is inversely proportional to operating temperature. The hotter they run, the sooner they die. So, maybe we shouldn’t be asking so much about the capsule temperature as the PCB temperature.

Tube Mic Temperature Testas mentioned on Recording Hacks.

I hung a temperature probe in an Apex Electronics 460Apex 460. The sensor was laying alongside the PCB. I let the mic warm up for several hours in each position.

Inverting the Apex 460 keeps the PCB ~8° F cooler. Inverting the Apex 460 keeps the capsule ~5°F cooler.

Dr. Charles Chen, the lead microphone designer at Lauten Audio.

Charles Chen

The tube will heat the air; as the hot air rises, it will increase the temperature of the air [surrounding] the capsule if the capsule is above the tube. Theoretically this will change the tension of the diaphragm a little bit, and therefore its frequency response. But the slight frequency change due to the temperature change might not be detected, and even if it is noticeable, we cannot say whether it is good or bad.

Further statements about the temperature:

Even at a higher temperature, the capacitor for which I ran the equation will live 60,000 hours. That gives you more than 20 years of daily 8-hour sessions before you have to find a replacement capacitor.

__________________________________________________ ______
+ On guitar I might actually have to turn it sideways to accomplish the mic position I want in conjunction with my other mics. Hmmm? This might be even better if indeed the Heat thing is a reality. As it will then miss both the capsule and the board?

What say you? Is there real value to the Upside down thing?

[Bob Womack]

There's an even better reason to turn them upside down: To get them out of the "blast cone" of a singer. "Blast cone" you ask? Think of an old acoustic megaphone, positioned at the mouth of a speaker or singer. That cone forms the area of probability of a pop from the blast from the singer's mouth caused by the air blast coming from plosives and dental consonants. You can say, "Two, two, two" over and over again while moving your hand around in front of your mouth and confirm it. As an engineer, you job is to get the mic out of that zone, the area of probability of p-pops. How can we do this? We can move it sideways, but any movement of the singer's face side to side will affect distance and proximity. We can put it below, but that's where the singer normally puts the lyrics, on a music stand. We can put it above, but the mic body hangs down and covers the upper part of the lyric sheet. We want the singer to elevate his/her head until the larynx isn't restricted, about level-headed.

Ah... Place the mic above nose level, inverted, with the body above the headshell. Angle your track lights to come in from each side. Voile'!!! Lyrics are neither covered by the body nor shadowed by it. Head is held up. Utter, complete pragmatism. No voodoo.

Bob

[phcorrigan]

I position mine sideways when I'm playing online so that it doesn't get in my way or block the camera's view of me.

[Brent Hahn]

If you look at photos of classically-trained singers, quite often you'll see that while their posture is erect and the back may be arched a bit, their head is facing directly forward and the chin is thrust down. They're trained to do this because this how you achieve the most open airway and relaxed musculature, and get the biggest sound. On those medical/rescue type TV shows where someone on a gurney has to be intubated, that's how they do it -- pick the head up from the back and push the chin down to relax the muscles and create the most space for the tube.

Try it yourself and see what the difference sounds like inside your own skull. And try recording it, too.

[DupleMeter]

That all started because of the u47. The heat caused issues with the capsule during marathon sessions, so they started hanging them upside down.

I still do it out of habit with tube mics. I’m not sure if it’s even necessary anymore.

[Bob Womack]

Originally Posted by DupleMeter

That all started because of the u47. The heat caused issues with the capsule during marathon sessions, so they started hanging them upside down.

Yep, it was related to the early capsules that had a different material used for the diaphragms that would indeed dry out. That problem was solved early on.

Bob

[DupleMeter]

Originally Posted by Bob Womack

Yep, it was related to the early capsules that had a different material used for the diaphragms that would indeed dry out. That problem was solved early on.

Bob

Yes. The old M7 versions of the u47 (which might be my favorite).

[Sasquatchian]

I have two of the Lauten Audio 386 tube mics and even after having them on all day they don't feel any hotter than when they were first turned on. On top of that, I opened one of mine up to make a product photo of it and was thinking it would look cool with the tube glowing in the shot, but even after leaving it plugged in and powered on for an hour there was still no visible glow. Still made a great photo but no heat.

[DupleMeter]

Originally Posted by Sasquatchian

I have two of the Lauten Audio 386 tube mics and even after having them on all day they don't feel any hotter than when they were first turned on. On top of that, I opened one of mine up to make a product photo of it and was thinking it would look cool with the tube glowing in the shot, but even after leaving it plugged in and powered on for an hour there was still no visible glow. Still made a great photo but no heat.

Hmmm…I wonder if they are cathode followers? That would explain the lower heat.

[KevWind]

I usually (but not always ) hang mine inverted but it is more for logistical reasons

#1 as Bob mentioned to get it out of the "blast" zone for plosives because I try to momentarily tip my mouth down for plosives and S'es
#2 I have my guitar mic's in the upward position
#3 and I have started videoing my sessions I place my camera/phone such that my face can be seen between the guitar mics and the vocal mic

Like this

[Brent Hahn]

Ducking the chin for p-pops is great if you can master it. And I haven’t seen it in a while, but I used to see old school narrators and occasionally a singer use their index finger as a momentary blast shield. This only works, of course, if you have an index finger that isn’t already doing something else.

[KevWind]

Originally Posted by Brent Hahn

Ducking the chin for p-pops is great if you can master it. And I haven’t seen it in a while, but I used to see old school narrators and occasionally a singer use their index finger as a momentary blast shield. This only works, of course, if you have an index finger that isn’t already doing something else.

I find I am inconsistent in doing it, so I guess I am in the practice phase The nice thing about having mic above is it takes very little down movement to lessen the pop effect

[Bob Womack]

There was a time when I was working with some of the top broadcast voices in the nation. Most of them had mastered turning their heads slightly off for a word or syllable when they were close to the mic and trying to avoid pops.

Another fascinating thing to watch with them was timing. Back before there was time stretching software, the best guys could re-time themselves on demand. They might read a piece of purported thirty-second copy and come up long or short. I'd be timing them and supply the length of that firsts read. They'd read again and hit the target time on the head on the second read, without a watch.

But then there were plenty who couldn't adjust their read. I got pretty good at editing mag tape to remove fractions here and there and bring a thirty-second read to agency length, twenty-eight and a half. The same with music. Everyone knew that agency length on a :30 was :25.5, but depending on the experience of the jingle composer or the rush the job demanded, we'd get in anything from :26 to :32 and had to edit to bring it to time, often just minutes before it went into a product or was put on air.

There was a lot of stress back then that I don't feel these days. Is it me?

Bob

[Glennwillow]

I have been using my LDC vocal mics in the inverted or upside down position for a lot of years simply because it gets the mic out of my way. From a video perspective, the mic is less in the way of the camera view of the singer, as well.

I still have occasional trouble with pops from plosives regardless of which pop filter I use or where I position the mic. I sometimes have to use a deplosive plug-in to get rid of the few pops in the vocal track. I do position my vocal mic fairly high, as Bob Womack showed in his photo, but again I do this to get the mic out of my way for the video.

I never considered the heat issues, but it's interesting that there is some history about that.

- Glenn

[DupleMeter]

Originally Posted by Brent Hahn

Ducking the chin for p-pops is great if you can master it. And I haven’t seen it in a while, but I used to see old school narrators and occasionally a singer use their index finger as a momentary blast shield. This only works, of course, if you have an index finger that isn’t already doing something else.

of course, there's always the pencil trick if all your fingers are otherwise occupied.