Crown CM310 Condenser Cable Consumer Microphone

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The CM310A vocal mic, best kept secret till now!

Jun 30, 2010
Review by  
Rated a Very Helpful Review

Pros:Great sound, Superior gain before feedback.

Cons:They are disscontinued. No service from Crown, Can't just have one!

The Bottom Line: Hands down the best studio sounding anti-feedback mic around!

Crown  CM310A
“Better late than never”, I always say! Sometime we go on using the same old stuff or doing the same ole’ same ole’ because #1…that’s the way it was always done…or…#2…my daddy did it that way….or…#3…we just don’t know there was anything different. When it comes to the CM310A vocal mic I feel all three falls into play.

Forever the standard stage vocal mic of choice for many bands, singers and sound companies has been the Shure SM58. It came out in the late 60’s early 70’s I believe. And has been used more than any other mic on the planet. Why you ask?

Well for one they were a very rugged mic, they were low in cost and for the time, there just wasn’t anything out there that sounded as good as the 58 in a dynamic package. But that was then, this is 2010 and times and technology change.

Enter the CM310A…which unfortunately are now discontinued.

One of the problems I always have had with the Shure 58 and other typical vocal mic’s are #1, they usually feedback in most rock and roll situation, #2. they do not always sound very good…#3…both of the above. This is my beef with the 58, I’ve never liked how it sounds (harsh to me) and they feedback something awful. Especially in a loud band situation with loud monitor mixes.

The CM310A was designed to eliminate all those frustrating sound man headaches!

It was introduced in June of 1987 as the CM300. It was a first of its kind with a new patent called a Differential Cardioid Microphone. Or Differential technology. What the heck is that? Glad you asked again.

Differential technology was a new concept a designed by Bruce Bartlett (former of Shure Bro’s, Astatic, Crown) and Tom Lininger (EV, Crown). It is a close-talking, hand-held differential-type condenser microphone for professional stage-vocal use. Frequency response is 60Hz-18kHz - unheard of for a differential microphone. The noise-canceling capsule provides exceptional gain-before-feedback.

It permits extremely loud monitor levels before feedback occurs. It gives you great headroom and great gain before feedback. This was accomplished due to Crown’s new patented methods of improving rear discrimination, far-field rejection, and high-frequency response. Rejecting unwanted background noise and leakage, and discriminates against distant sound sources such as monitor loudspeakers or instruments.

How is this done?
The mic-to-source distance affects the gain of the voice. What does that mean? Simple, The closer to a singer that a microphone is placed, the louder the sound is through the
sound system (because of the inverse-square law). Distant miking sounds are
quieter; close miking sounds are louder. So logic dictates that’s mounting the microphone
capsule close to the singer’s mouth in order to get plenty of gain will reduce unwanted background leakage and unwanted feedback. The Differoid microphone does this very well.

In the Differoid CM300 mic… the designers mounted the microphone capsule at the
optimum distance from the mouth -- close enough for plenty of volume, but
not so close as to degrade the sound quality. Crown recommended that the singer lips lightly touch the front of the CM300’s grill.

By placing the Capsule/Element internally a ½ inch or less from the grill gives exceptional gain before feedback. But what about the law of Proximity effect? What’s that you asked? Well remember we talked about the inverse-square law? With any Cardioid or Super Cardioid hand held vocal mic you get Proximity effect. When the singer has the mic very close to the mic, the voice is going to sound fuller and louder, and depending of the singer and vocal mic used, too bassy and at times “muddy”.

This is the proper way to place a vocal mic, but the sound man usually has to roll off the extra lowed that accrues. This is Proximity effect. When the singer backs off the mic, and they usually do, moving the mic around….. being all…..singer-ish…ha, think of Maria Carey or Celine Dion, the vocal can become very thin and harsh at times. Or they just disappear!

So how is the CM300 any different?

The Differential technology solves this by #1….placing the capsule internally very close to the grill. #2...internally eq-ing the low bassy frequencies out. Or in other words rolling off the unwanted low end bass boost caused by Proximity effect. This is done in the mic’s electronic circuit module internally. This resulted in a smooth natural frequency response and superior gain before feedback and unwanted background leakage. When the mic is placed up close to the singer lips.

CM300 becomes the CM310/CM310A.
The CM300 did have its fair share of problems in the beginning. First. It used a different smaller capsule/element and was very time consuming and troublesome with the fine tuning of it during manufacturing. #2. It did work well but not as good as we hoped for, so a re-design with a larger capsule/element and specialized electronics’ solved the problem. Resulting in greater gain before feedback, smoother more controlled frequency response and easier assembly and testing.
The CM-310A became in Nov. 1994. Compared to the CM300/CM-310, the CM-310A has:
Better handling of powerful breath pops without cutting out or blockingA more streamlined, attractive grille A cleaner sound with reduced midbass Smoother frequency responseTighter off axis rejectionHigher Gain before feedback
The CM-310A spec’s.
Transducer type: Electret condenser.

Frequency response (typical): 80 Hz to 15,000 Hz.
Polar pattern: Cardioid.

Impedance: 200 ohms balanced. Recommended
minimum load impedance 1000 ohms.

Open circuit sensitivity, typical, close talking: 1.7
mV/Pa* (–55.5 dBV/Pa).

Power sensitivity, typical, close talking: –54.5 dB re
1 mW/Pa*.

Equivalent noise level (self-noise): 21.5 dB SPL
typical (0 dB = 0.0002 dyne/cm2), A-weighted.

S/N Ratio: 72.5 dB at 94 dB SPL.

Maximum SPL for 3% THD: 151 dB SPL with 48V
phantom, 143 dB SPL with 12V phantom.

Operating voltage: Phantom power, 12V to 48V DC,
positive voltage on pins 2 and 3 with respect to pin
1 of output connector.

Polarity: Positive pressure on the diaphragm produces
a positive voltage on pin 2 with respect to
pin 3 of output connector.

Current drain: 1.7 milliamperes.

Cable: None supplied; use 2-conductor shielded
microphone cable.

Connector: 3-pin professional audio connector (XLR

Switches: Internal DIP switch on PC board sets
frequency response to FLAT or RISING. The
CM-310ASW also has a magnetic reed switch in
the handle that turns the mic on and off.

Materials: Rugged aluminum alloy housing, steel

Finish: Satin black.

Net weight: 7.1 oz. (200 g).

Included accessories: Carrying pouch, ASA-2 microphone
stand adapter and WS-4 windscreen.

Optional accessories: Crown PH-1A phantom power
supply (1 channel, battery or AC adapter powered).

Replacement parts:
Field-replaceable grillescreen is available from Crown’s Parts Department.

Spec’s taken from here!

My Personal Experience with the CM310A
I have been using the CM310A since the day they came out. I have used them in many live situations and even in the studio. I have been playing in loud rock and roll situations for years and the CM310A is the only vocal mic I use. Anytime I try to use a Shure SM58 or EV n-Dyme I get feedback out of the monitors. And I usually only want my vocal and a little of the other singers, is that too much to ask. The CM310A solves my problem every time.

Around 1995-96 I formed a Blues R&B band with my ex wife…and still, the same situation here. I tried to use a 58 or EV on her lead vocals. I just could not make her happy enough with getting her vocal monitor loud enough over the band stage mix. Not so much because we played loud, but we played very small clubs and places and we’d be packed into an area 14x14 sometimes. As a bass amp is blaring at her one ear while my guitar amp is blaring at the other and the drummer directly behind her with cymbals crashing. What do you think her standard SM58 vocal mic was picking up? Right…..everything but her vocal! And feedback up the ying yang! So I swapped out that old school 58 for CM310a’s and presto, problem solved. Fact is I could get her vocal monitor mix so loud she at times would ask me to turn it down. Hey sound dawgs how many times do you have a vocal chick ask you to turn her down? Not many times Id bet, especially in a situation like this.  Fact, on 2 occasions I blew up the drivers in her monitor because she was so loud. And all there was in that monitor was just her vocal! Again no feedback.

2010 live situation.
March of this year I organized and produced and large Haiti benefit at one of the biggest clubs in Northern Indiana. We had 7 bands of all types of styles. My mentor and great friend (and original design engineer of the CM310A) Bruce Bartlett, help me mix and engineer the sound for the show. Bruce wanted to start off with CM200a’s (yes he designed them too) for all the vocal mic’s. I was apprehensive as the CM200A is a wonderful sounding vocal mic, and yes does sonically sound better than the CM310A and SM58 but I knew we would have problems. I expressed this to Bruce saying…… “Bruce daddy, you know we are going to have feedback, these bands I’m sure are going to be loud and want loud mixes.” He said he knew but the CM200A sounds better and that he wanted to use them anyway. I was ok dawg, your the boss, but I said “as soon as we get the first monitor ringing with feedback, we are putting up the CM310A’s.” He said “ok.”

Sure enough….60 seconds into the first bands (middle crossings) song feedback and ringing started. I just stayed quiet….after that first song of basically mush and ringing and Bruce tweaking the board and monitor mix, it stilled remained. Now the band is frustrated and are wanting more vocal in the monitors because we/I grabbed the whole monitor mix and turned it down! After the second song Bruce looks over and say’s “I think you’re right, we need those CM310A’s”. Luckily enough, I brought about 10 of my personal ones and we took a 10 minute break to swap out all 5 vocal mic’s with them. “Pause for the cause.”

The band started the next song and presto, problem solved, I turned the monitor mix back up even louder and a few guy’s in the band motioned me to back off their individual monitors. We also could rest the eq on the monitors to flat and just notch out slightly a few troublesome frequencies that was messing with the room acoustics!

Bruce comment again… “You were right, those CM310A’s rock”. I said “Bruce baddy, you invented them, remember?”…….” “Oh jeeeee ha ha”,

Live studio situation & live sound.

Another wonderful application this mic shines on is the snare drum. What??? Thought this was a vocal mic? Yup! So is the SM58 and SM57 and you’ve seen them on snare and percussion for years. I actually do love the sound of a SM57 on the snare…crisp and tight, poppy sound! But my issue is the off axis leakage. I can get a great snare sound but I also get a great Hi-Hat sound leaking into it too! Your average sound guy tries to fix this by slapping on a compressor/gate and gating the hi-hat out. This I hate, it changes the sound of the snare and 9x’s out of ten I can hear the gate chopping off the hi-hat as soon as it closes.

Enter the CM310A again to save the day. The frequency response of the mic is very similar to a SM57 so you can get the same sound, but the off axis rejection is superior. Just put the CM310A up close to the snare and aim the null of the mic at the Hi-Hat! Done, simple…solved! You get a bright, tight and snappy…..natural snare….and only snare. No gates necessary! Works great in the studio when you want a clean, natural snare recorded to tape! Yes I still use tape!

Other CM310A users and testimonies!
Many artist I worked with and supported at Crown are:
·        Michael Jackson
Nirvana- Lead vocals Curt Cobain. Craig Montgomery, chief audio engineer for Nirvana, has endorsed Crown CM-310 [now the CM-310A] Differoid microphones, using them for all vocal applications in the red-hot band’s live performance. Seattle-based Nirvana burst upon the rock/pop scene last year with their trendsetting sound, most commonly described as “grunge metal.” With raw music that’s heavy on guitar distortion, getting the right mix presents a true challenge for Montgomery and his crew, a challenge made easier since he discovered the CM-310. “Our primary problem was the bleeding of extremely loud guitar amplifier noise into the vocal mix,”Montgomery explains. “It generally runs from three to six dB hotter than our vocals, giving us a very bad situation with stage monitors. We simply had too much guitar bleeding through and couldn’t hear our vocals.”

Enter the CM-310. Offering superb gain-before-feedback, the CM-310 is a differential-type cardioid
microphone that provides unmatched suppression of unwanted background noise and rejection of
other stage noise. After discovering the mic, Montgomery, working with touring company Proshow
USA of Seattle, equipped lead vocalist/guitarist Kurt Cobain, bassist Chris Novoselic and drummer
Dave Grohl with CM-310’s for all vocals.

“We had tried a variety of the ‘typical’ mics available for live performance without a lot of success,” he says. “But the first time we used the CM-310, the unwanted noise went way down. In fact, it was at
least 20 dB quieter than anything we had previously tried.”

Montgomery adds that he has also found the CM-310 very effective in cutting out cymbal sound leakage
into the vocal mix of drummer Grohl. “And although Chris (bassist) doesn’t sing very much, he
likes to have an open mic in front of him for interaction with the audience during a show. With the
CM-310, we’re now able to leave his mic open at all times without worrying about destroying the mix.”
·        Travis Tritt — lead vocal An engineer with Travis Tritt said “It’s an excellent microphone — we’re very happy with it.”
·        Martina McBride — lead vocal
·        Rap artist Hammer — nine choir members. Harald Danker, Hammer’s monitor engineer said that he needed a mic that rejected noise and feedback. Since 14 mics were open on stage at all times, this was crucial. The mics are used by the chorus or choir of 14 members (now nine). Harald says that he is delighted with the noise and feedback rejection of the CM-310. He notes that the stage is just too noisy for any other microphones because the band and monitors are very loud.
·        Aaron Tippin — lead vocal
·         Bryan Adams
The Dave Matthews Band Ian Kuhn, monitor mixer for the band, had this to say about the CM-310A Differoid mic used during their recent tour: “Drummer Carter Beauford sings into a Crown CM-310A Differoid. A CM-310A is also used for Moore’s vocal and doubles as his flute mic. The Differoid gives us great rejection and isolates the sound source, and Beauford definitely likes his vocal screaming.”
Source: Mark Frink, “A Stage-Eye View of the Dave Matthews Band,” Feb. ’97 issue of Mix Magazine.
Presidents of the United States of America Band member Dave Dederer talked about the mics they used to record the vocals: “We did most of the vocal takes at Litho with live vocal mics. We didn’t use fancy studio mics, just the same ones we used on the road. It was a Crown condenser [CM-310a], and that works for us. It gets a nice, warm, up-front kinda sound, and you don’t get psyched out the the pop-screen, four-milliondollar mic that you’re totally afraid of.”Vocalist Chris Ballew agrees. “I hate those [big studio mics]! You can’t put your lips on ‘em! How are you supposed to sing without putting your lips on the mic?” Band members recorded most of the album with their lips touching the grilles of the CM-310a Differoid mics.
·        Grover Washington, Jr. — vocalists on European tour
·        38 Special using Crown Differoids (CM-310’s) on all their vocals and guitar amps. They say that the 310 sounds natural, and has no feedback or ringing problems. According to group member Rob Wilson, “We enjoyed using the CM 310’s on our triple bill with REO Speedwagon, Cheap Trick and .38 Special. We had a consistently superior vocal sound for all shows.”
·        Restless Heart used Differoids when they performed on the Jay Leno show.
·        Country Music Television
·        the Nashville Network
·        Dan Seals Tim Rathert, sound designer and mixing engineer for Dan Seals, “The 310s are a closer approximation to the tube mics we use in the studio than anything else we’ve ever used... A critical choosing point was mic performance with an in-the-ear monitoring system. With the Differoid, the fidelity that Dan heard was incredible.”
Richard Johnson, a sound engineer for HSA/Heather Sound ““When you get into an environment that’s hideous — loud stage, loud room, bad room — whether it’s
rock and roll or Contemporary Christian, the sweet sound of most microphones tends to be washed
away in the midst of all these problems. That’s where the CM-310 suddenly sounds very, very good.
It will eliminate a lot of the bleed, and it will be quicker to EQ, both main and monitor. That means
you spend less time EQing the monitors by ringing them out [making them feed back]. You tend to be
able to EQ by sound quality. When you get into the stressful, high-power, high-level type of stages with a lot of things going on.”
Jeremiah Hamilton, Staff Technician with Bernhard-Brown, “CM-310s are especially valuable when the P.A. speakers aim at the microphone: “In the summer of ’89 we did the Summer Olympic Festival in Norman, Oklahoma, in the major stadium there with about 75,000 people. The problem was proximity feedback because of the volume level on the field where the announcer was. The speakers were facing right at the announcer, and we had to have something that would really do the job”. The Cm310A solved this![Prominent sound engineer] Tom Durell in LA recommended the Crown CM-310; “we had a couple flown in, and it did the job admirably. We’ve used it several times in announcer situations, and we’ve had no worries at all about speaker proximity.”John Windham of Morningstar Productions “We no longer have the problem. We are now using the Crown CM-310 Differoid [now the CM-310A].It has completely solved our feedback problem.”Tim Prince of Starstruck Entertainment works with Aaron Tippin. According to Prince, “We couldn’t find a mic that sounded as good with as little feedback as the CM-310. Its unique design allows youto get high monitor volume without feedback. I love that mic. It’s a real useful instrument.” Prince said that Tippin tends to have a harsh singing voice, which is well complemented by the flat,smooth sound of the Differoid. He also said that he doesn’t have to mute the mic when it’s not in use,because it picks up so little leakage. “It acts like it’s gated.”Dave Stevens: Nirvana’s system engineer “Prior to enlisting these new mics for the Nirvana shows, sometimes the guitar tones were being hollowed out by a lot of SPL coming offstage. There was an inordinate amount of leakage on the front line, in large part because everyone has a vocal mic. “In trying to solve the problem, [house mixer] Craig Montgomery had read an article touting the virtues of Differoid mics. He asked for some, and we obliged. The first time they were used was at the MTV Music Awards, and they performed admirably. “During the dates in September, we found that you could trim the microphones at a level that wouldn’t pick up noise from the stage even when you backed away from them. A lot of phase canceling occurs except [for sound directly on axis]. As a result, that ‘whoosh-whoosh’ you typically get with a dynamic
      Cardioid microphone when the vocalist steps away was gone.”
Bob Larsen WUSN (US-99) Chicago

Comments taken from the Spring 1991 Mic Memo & Fall 1992, 93 & summer of 94.
Bruce Bartlett, editor/design engineer
As you can see, these are some heavy hitting comments coming from major players in the entertainment field!

Pit falls with this mic?
The mic really has no major pitfall, it really is as good as it sounds. The problem is with the singer. You have to re-train them to use it correctly. As stated, a singer must have this mic placed directly in front of their mouth with the lips slightly touching it to achieve the great performance and gain before feedback rejection. Some singers do not like this and can’t get used to it. Some I have met just refuse. They want to be able to “work the mic”…. So heck whatever, then you will not get a great clean punchy monitor mix. It’s that simple.

But I suppose the biggest problem now is, unfortunately, these mic’s have been discontinued by Crown. And finding them and people who want to part with them are rare. Ebay again is your best bet.

Another problem is the service ability of them. There are little to no replacement parts left and Crown no longer supports this product. AKG has taken over the Crown microphone responsibilities and let me tell you…they have no parts either or the training to even look at them. Good news……. I do! Call me if you need yours fixed!

In Closing, I recommend these mic hands down, without question. They work on all situations where you need a studio sounding mic and high gain before feedback. Good luck finding them, when you do guard them with your life!

Thanks For reading
Mark R Darnell
Groovebelly Productions
CEO/Owner Operator.

P.S No I will not sell mine! ;)

Recommend this product? Yes

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