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The Electro-Voice 666 and 666R
cardioid dynamic microphones

(Scroll halfway down for information on the 667)

Electro-Voice Model 666R

Description and Applications
The Model 666 is a cardioid microphone of the dynamic type. The Model 667 is a Model 666 microphone used in conjunction with an in-line transistor preamplifier, which can be seen halfway down this page. The cardioid pattern is obtained through use of three sound entrances located in the microphone case at different distances in back of the diaphragm. The three sound entrances, each utilizing the proper acoustical impedance, combine to form one effective back entrance, which varies in distance from the diaphragm inversely with frequency. The resulting phase and amplitude conditions produce a uniform range at the flat position on the preamplifier. This variable front-to-back distance along with dynamic con­struction affords high resistance to mechanical shock and produces virtually no proximity effect. The front-to-back ratio is double to triple that of the average cardioid microphone.

The Model 666 on the left carries Serial Number 1760. On the right is another Model 666 with Serial Number 3048. Notice the mic on the left is fitted with plain metallic port inserts that are drilled. The opening closest to the front of the mic is .09375" while the opening at the rear is .0625". The mic on the right is equipped with a black plastic molded insert near the front of the mic, while its rear port is part of the main mic body casting, and is tapered. Both openings are .125" on the right-hand mic. Is the mic on the left a prototype?

The Model 666 is an all-purpose microphone designed to fulfill require­ments of wide-range reproduction under a great variety of conditions. Because of its excellent uniform polar response, it is especially useful in locations where ambient noise and severe reverberation exist. Added gain from the preamplifier plus uniform polar response makes this microphone ideally suited for long-throw boom applications. The Model 666 can also be used on a floor or desk stand or carried in the hand.

The microphone head features the exclusive Electro-Voice Acousalloy dia­phragm. This nonmetallic diaphragm produces smooth response over a wide frequency range and withstands high humidity, temperature extremes, corrosive effects of salt air, and severe mechanical shocks. It is practically indestructible with normal use.


A chrome version of the Electro-Voice 666.

Specifications for the E-V 666 and 666R

Illustrations and text are from Electro-Voice,
Engineering Data Sheet Part No. 53258

The Model 666

The Electro-Voice Model 666 cardioid dynamic microphone.

UA-3-11 connector

The rare and coveted Cannon UA-3-11 connector.

In its case 666 666R EDS

Download the Specifications for the 666/666R.

The Electro-Voice Model 667
cardioid dynamic mic and preamplifier

E-V 667 Preamplifier and mic
Hear the sound of this mic and preamp.
Hear the bass roll-off comparison.

The in-line transistor preamplifier is designed to exhibit an excellent dy­namic range (see specifications). Individual bass and treble controls select any one of twenty frequency response characteristics for exacting appli­cations. Tantalum capacitors, mylar capacitors, and 1 per cent metallic film, low-noise resistors used in critical circuits maximize output stability and low-noise operation. Since transistors and associated equipment are characteristically temperature sensitive, they are housed in protective pots to minimize adverse effects on the dynamic range due to sudden tempera­ture variations. A slight decrease in dynamic range will be effected at operating temperatures greater than 80 degrees F. The preamplifier should be operated at room temperatures never exceeding 90 degrees F. Tem­peratures greater than 90 degrees F will not physically harm the preamplifier, but there will be a noticeable decrease in dynamic range.

E-V Model 667 Preamplifier

The preamplifier section utilizes a Mallory-type TR-115 mercury battery with a minimum operating life of 350 hours. However, for best results, change batteries every 300 hours. To replace the battery, remove the two knurled thumbscrews holding the nameplate. Caution note: Observe polarity when inserting.

If a different length connecting cable is added between the microphone head and preamplifier, ground the cable shield to the G pin of the UA-3-12 connector. No shield connection is made on the microphone end. The cable shield lead from the preamplifier to the control console should be connected to the red ground lead at the console end of the cable.

Precision production techniques and individual laboratory calibration of the Model 666 microphone and the Model 667 preamplifier insure uniformity beyond that of the average broadcast microphone.

E-V Model 667 Preamplifier

The original UA-3-11 and UA-3-12 connectors have been replaced with XLRs.

The correct connectors

This one has the original connectors. Our thanks to
James U. Steele for this photo. Rest in Peace, Jim.

Beneath the preamp

Our thanks to Rick Chinn for the photo above and the schematic below.

Small schematic

Download a 2180 by 1410 pixel GIF of this schematic. (140 K)

E-V Model 667 Specifications

Quoted from the Electro-Voice Model 667 Micro-
phone Specifications
sheet, Part No. 53471

Preamp and mic in box

Model 667 Variable Response Cardioid
This all-purpose microphone fulfills requirements of wide-range repro­duction under a great variety of acoustic conditions. The 667 combines the same excellent cardioid operations of the Model 666, with an in-line transistor preamplifier with bass, treble and presence controls providing 40 distinct frequency response characteristics. Maximum output level: 50 ohms, -30 dB; 150 ohms, -32 dB; 250 ohms, -33 dB. Microphone specifica­tions and accessories are similar to those of the Model 666 except response: 35-16,000 cps; finish brown and gold. Preamplifier noise level -123 dB referred to input. Controls: Bass (four-position: +3 dB, flat; -5 dB, -9 dB at 100 cps); Treble (five-position: +9 dB, +6 dB, +3 dB, flat; -6 dB at 10 kc); Gain (four-position). Power On-Off switch. Long-life mercury battery supplied. Steel case, brushed chrome finish. Supplied with 50-foot cable, UA-3-11, UA-3-12 connectors; 20-foot cable with UA-3-11 connector. Hardwood carrying case for complete unit. When originally offered, the list price was $600 including the microphone.

The following twelve images were provided via the courtesy of Jim Gerard.

01 02 03 04 05 06 07 08 09 10 11 12 Low frequency curves

The Model 667 low frequency curves.

Medium frequency curves

Midrange frequency equalization curve.

High frequency curves

High frequency curves. Charts are courtesy of Rick Chinn.

E-V Model 667 Preamplifier box

Versatility Plus
by Jack Bayha

A new microphone aimed at answering every recording need with widely reliable frequency response has been introduced by Electro-Voice, Inc., Buchanan, Michigan. This is the 667, a cardioid dynamic mike, with a transistorized preamplifier.

The E-V 667 is the result, we suspect, of repeated listening on the part of the E-V Sales Department to requests for a higher level output, a lower level output, more highs, more lows, less lows, and other assorted recording studio requests. Based on the widely used and popular 666, the 667 represents their answer to the need for a widely flexible high fidelity recording microphone of the finest quality. It has variable frequency response and a noise level of −123 dbm referred to input.

We heard about the E-V 667 well before it was public knowledge, and wondered just how it was possible to do all the things we had heard it would do. Of course the answer was obvious: use a transistor amplifier, have it equipped with variable output levels, and some controls. As far as we can ascertain, the E-V 667 is merely a 666 with a transistor amplifier, but what this little chrome-plated box can do is fabulous.

We had an E-V 667 in our possession for a month, and ran it through our usual tests. This was not easy, however. Where in the past we could rate a microphone for its high frequency response and its low end, we found we could make these most anything we wanted merely by turning a couple of switches. Where in the past we could measure a microphone’s output, with the 667 we could turn a switch and get levels which would overload any microphone input we wanted to. Needless to say, we took it out in the field, and find ourselves a strong advocate of this type of versatility. We could get anything response-wise we wanted, from flat to the exaggerated high end common to a certain capacitor mike now in high favor. From its very plush carrying case to its rich gold-plated screening we found it to be a terrific microphone, and certainly a wonderful device for the recordist who can afford its price tag, although it does cost less than any other unit we can think of with its performance and truly amazing versatility. The price is $600 list, user net less than $375.

It has one performance limitation not common to other mikes, in that it cannot be operated at temperatures in excess of 90 degrees without impairing its wide dynamic range, although the microphone will not be damaged. But shucks, that’s too hot to record in anyway! We have taken curves of the microphone, and the charts from our own sources closely match the manufacturer’s claim.

In conclusion, we feel that this is the answer to all those recordists who want versatility, quality performance, and can afford what looks like the best yet.

Ms. Betsy E. Bayha writes: Jack Bayha was my father, and worked for The Voice of Music in Benton Harbor, Michigan during the mid fifties. He had a varied career and was a prolific inventor in a variety of areas, but is probably best known for his work in the optical field (specifically, dollar-bill changers) in the sixties and seventies. He passed away in 1996.

Electro-Voice 666R Electro-Voice 666R Electro-Voice 666R Electro-Voice 666R Electro-Voice 666R Electro-Voice 666R 1957

A magazine advertisement from 1957.

Spec sheet

Download the Specifications for this mic and preamp.

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