Strange Looking Grateful Dead Vocal Mics ??

[akg414]

Does anybody know what kind of vocal mics the Dead used on stage? They are really strange looking: with two bars that look like each contains a seperate mic initself. Any clues?

[drumsound]

I remember a bunch of pictures and videos stuff with two mics right next to each other. I figure one to the PA one to the recording rig.

[JGriffin]

I figure one to the PA one to the recording rig.

got it in one.

[Mix413]

I believe those were a reverse polarity canceling pair for minimizing bleed when recording. I think it was an idea that didn't quite pan out. There was an interesting thread a few years ago on rec.audio.pro about those mics . Like their music or not, you've got to tip your hat to The Dead for their adventurous early seventies gear exploits.

[JGriffin]

I believe those were a reverse polarity canceling pair for minimizing bleed when recording. I think it was an idea that didn't quite pan out. There was an interesting thread a few years ago on rec.audio.pro about those mics . Like their music or not, you've got to tip your hat to The Dead for their adventurous early seventies gear exploits.

Oh yeah, good point. i remembber reading about that in college. Aright, I stand corrected possibly.

[Freakmagnet451]

You will see photos of the Dead playing in FRONT of the house PA with those mics. They were using an Alembic system, a giant wall of speakers and the mics were out of phase to cancel feedback. Anything that was the same to both mics was canceled so they sung from the side towards one mic and it worked!! Completely insane but it worked. Not a Dead-head at all, saw them in the day with PigPen on keys and vocals and just never got the Dead thing. Still, they were innovators in the realm of audio endeavor.

[akg414]

They were using an Alembic system, a giant wall of speakers and the mics were out of phase to cancel feedback.

Thanks Freakmagnet451: that was the answer I was looking for. You gave me the "what" - and added in a little "why"!

[JASIII]

If you listen to live recordings of that era, the use of that mic'ing system led to very pinched, nasally sounding vox. Worked well for cancelling feedback, not so hot for a good vocal sound.

[???????]

maybe it would've worked better if the mics were a foot further apart?

[farview]

maybe it would've worked better if the mics were a foot further apart?

They have to be real close to each other. Otherwise, they aren't picking up the same sound and the cancellation won't work. It really is much easier to put the band behind the PA.

[Packy]

Here's way more info than you want on those mics...this is from a pretty detailed article about the whole 1974 Wall of Sound system. (http://dozin.com/wallofsound/index.html) The vocals usually never sounded too hot, but when all the Wall's cylinders were firing (rarely) apparently it was the best live sound has ever been. At least that's what my dad says...

I for one am a HUGE deadhead as well as your usual gearhead TOMBer...if you or anyone's interested in the Wall let me know, I love chatting about it

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A major improvement in the quality of the vocal sound is due to the use of differential microphones. Each singer has a perfectly matched pair of Bruel and Kjaer microphones hooked up out if phase, only one of which he sings into. Any sound which goes equally into both microphones is canceled out when the two signals are added together. Therefore leakage of instruments and background noise into the vocal channel are minimized

Microphones

We had used various commercial microphones and found omnidirectional and continuously variable D types to have satisfactory sound characteristics (naturalness) for the vocals. But since it was our desire to exclude the instrumental sound from the vocal system we had a problem which could not be solved by a directional microphone because the instrument loudspeakers are located behind the vocalists on axis with the desired pickup. Therefore we turned to the dipole type in which the response is a function of the difference of the sound pressures at two distinct points. This configuration today (1975) is usually called a differential microphone, and as a close-talking microphone, the output is independent of frequency. This is a first-order gradient microphone and it possesses excellent antinoise characteristics. We place the pressure microphones about 60 mm apart. Wider separations reduce the effectiveness for higher frequencies and closer spacings can roll-off the low frequency in voice since the low frequencies of the vocalist can be heard by both microphones.


Our first implementation was with two dynamic microphones connected in series opposition. When the input impedance is much higher than the geneator impedance of the microphone, each can generate its voltage properly and excellent results are obtained.
(We do not recommend the reverse-polarity parallel connection as the inductance of the second microphone will attenuate the low frequencies of the vocal microphone in the same manner as a "voice" response inductor which is switchable in many microphones to roll off the bass response.) Often, splitter connections must be made to the microphones for recording and live broadcasting and under these conditions, the simple connection shown which offers a relative independence of loading effects. By this time we had achieved pretty good rejection of our instrument sound field but we felt that with closer matched microphones we could do even better.

We tried condenser measuring microphones from various manufacturers but found only one which would give us better matching than the dynamic microphones. For the final system, we asked this manufacturer to select a series of elements matched in amplitude and phase and obtained elements with amplitude match better than ? 0.1db and phase match better than 1 degree at 10KHz! This precise match made our noise canceling performance outstanding and the sound quality of the microphone for music is unexcelled. We used preamplifiers designed to use the measuring microphone elements with an instrumentation tape recorder but modified them for greater dynamic range.

All the direct (vocal) microphones were resistively summed and all the ambiance (noise canceling) microphones were resistively summed and then the difference was taken by an ultra low distortion amplifier. No conventional gain controls were used and thus the signal path was kept as clean as possible. The sensitivity of the microphones is controlled by varying the polarizing voltage applied to the condenser element. The same voltage is applied to both microphones of the differential pair, preserving the noise-cancelling capability.

A control is mounted on as small box which serves as the mounting structure for the microphone. This control permits the performer to control the output of his microphone. Provisions are also made to remotely control the sensitivity when announcements are being made by persons unfamiliar with the system. On the remote control panel is a switch for each microphone which convert it to an omnidirectional microphone by bypassing the ambiance element.

For recording and broadcasting, each microphone is provided with separate difference amplifiers which has two transformer isolated outputs. Each microphone may then be recorded on a separate track.

Because of the antinoise characteristics of the microphones, the sensitivity drops off rapidly when one moves away from the element. This causes some problems for first-time users who must not wander around as they may be accustomed to with conventional microphones. There are those who reject the microphones for this reason. Heaters should be provided for the microphones since considerable condensation from the breath can load the diaphragm and destroy the match of the elements.

[Johnny B]

Here's way more info than you want on those mics...this is from a pretty detailed article about the whole 1974 Wall of Sound system. (http://dozin.com/wallofsound/index.html) The vocals usually never sounded too hot,

Typical Grateful Dead show, then, eh?

[Packy]

touche mate, touche...

[wayne kerr]

Does anybody know what kind of vocal mics the Dead used on stage? They are really strange looking: with two bars that look like each contains a seperate mic initself. Any clues?

Dude, they use 57s like everyone else. All that acid must've made 'em look funny to you.

[ckeene]

Here's way more info than you want on those mics...this is from a pretty detailed article about the whole 1974 Wall of Sound system. (http://dozin.com/wallofsound/index.html) The vocals usually never sounded too hot, but when all the Wall's cylinders were firing (rarely) apparently it was the best live sound has ever been. At least that's what my dad says...

I for one am a HUGE deadhead as well as your usual gearhead TOMBer...if you or anyone's interested in the Wall let me know, I love chatting about it

Wall of Sound is completely fascinating to me. Unfortunately I was too young to have seen it in action, and as a reformed punk rock guy have only recently made my peace with the Dead.

I have to wonder, given today's PA equipment, how much smaller a packege this could be done in and deliver an equivalent overall SPL?