Hermetically sealed condenser microphone by Rebecca
Hermetically sealed condenser microphone including an outer sealing diaphragm hermetically sealing an electroacoustic transducer within a case from the outside environment. The sealing diaphragm passes sound undiminished through an underlying intervening air space to a second active diaphragm of the electroacoustic transducer.
Specifically, the case has a hollow interior, a sealed end and an open end. The electroacoustic transducer is disposed within the hollow interior of the case, and the sealing diaphragm disposed over the top of the open end of the case such that the hollow interior of the case is completely sealed. An acoustic signal first impinges upon the sealing diaphragm causing deflections therein which in turn recreate the acoustic signal undiminished in the air space within the case between the sealing diaphragm and the active diaphragm.
The recreated acoustic signal then impinges on the active diaphragm of the electroacoustic transducer causing deflections therein that are converted to an electrical signal outputable from the microphone. Thus, the sealing diaphragm prevents water vapor and other contaminants from coming into contact with the internal components of the microphone, while still allowing the acoustic signal to reach the active diaphragm.
Condenser microphones are widely used to convert acoustic signals to proportionate electrical signals, such as is necessary in electronic voice communication applications. These conventional microphones typically include a capacitive transducer made in such a manner that one electrode of a capacitor structure is formed by an electrically conductive diaphragm. This diaphragm is disposed adjacent to, but insulated from, a stationary electrode forming the second electrode of the capacitor structure. The two electrodes are spaced apart with an air gap in-between. A relatively high DC bias voltage is applied between the electrodes. Variations in the electrode spacing caused by deflections of the diaphragm in response to the force of acoustic wave energy incident on the diaphragm, produce a change in capacitance. A detection network is connected to the capacitive transducer such that the change in capacitance is detected and transformed into an electrical signal proportional to the force of the acoustic wave energy applied to the diaphragm.
Conventional condenser microphones have not been completely sealed from the atmosphere in the past because they would become inoperative in the face of variations in barometric pressure or altitude. For instance, an increase in the atmospheric pressure outside the diaphragm would tend to deflect it towards the stationary planar electrode of the transducer, thus introducing an error in the electrical signal output from the device and reducing the device’s sensitivity to actual acoustic inputs. To alleviate this problem, traditional condenser microphones included a vent or pressure relief hole in the diaphragm, which allowed air to flow between the region outside and inside of the diaphragm to equalize the pressure and prevent the aforementioned unwanted deflection.
Although the diaphragm vent hole prevented changes in external pressure from affecting the performance of the microphone, it also introduced some undesirable side effects. For instance, water vapor can be introduced into the air space between the diaphragm and the stationary electrode when air having a high relative humidity is drawn onto this space to equalize an increase in the external air pressure. This water vapor can have deteriorative effects on the transducer components. Similarly, if the microphone was submersed in water, the vent hole would allow water into the space inside the diaphragm, thereby damaging or making the transducer inoperative. In addition, the vent hole allows contaminants, such as dust, to enter the space under the diaphragm. This could cause electrical noise if the contaminants come into contact with the sensitive stationary electrode of the transducer, or possibly with the electronics of the detector circuit. The contaminants might also clog the vent hole and cause the same problems described previously in connection with the need for a equalization port in the diaphragm.
The only heretofore known microphone that has been sealed from its outside environment are those employing a diaphragm with a high mechanical impedance. A hydrophone is an example of this type of microphone. These microphones have a bladder connected to the space behind the diaphragm which expands and contracts to equalize the aforementioned internal/external pressure difference. However, a condenser microphone requires a diaphragm having a much lower mechanical impedance. A bladder consistent with the size of a condenser microphone would not be able to absorb all the air displacement necessary to equalize the inside pressure to that of the ambient environment.
Therefore, what is needed is a condenser microphone which is completely sealed from the environment external to the diaphragm of the transducer, and still capable of operating efficiently in the face of changing ambient pressures.
Ningbo Tongxin Microphones offers the best variety of quality Condenser Microphone for Studio, Podcast, USB, Instrumen, Conference, Broadcast and Field Recording.
Article Source: http://www.earticlesonline.com/Article/Hermetically-sealed-condenser-microphone/853541
Record Collection – Still sealed Vinyl
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2009 PIEDFORT 40TH ANNIV 50p FIFTY PENCE GOLD PROOF 16 COIN STILL MINT SEALED $57,999.95 |
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AUDEMARS PIGUET DIVER – STILL SEALED IN PLASTIC – BLOW OUT SALE $ 15,495.00 $15,495.00 |
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2006 W 1OZ $100 Burnished Platinum Eagle Still sealed in Mint Packaging $4,750.00 |
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2000 MILLENNIUM £5 FIVE POUND GOLD BULLION COIN STILL MINT SEALED $3,199.95 |
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SCARCE SOLID .9999 FINE GOLD BULLION 2008 $50 USA BUFFALO COIN – STILL SEALED! $2,899.95 |
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DENNIS HOPPER – PHOTOGRAPHS 1961-1967 LTD 1/1500 NEW – SIGNED & STILL SEALED $2,650.00 |
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1996 PRESS PASS ~ BOBBY LABONTE ~ TIRE CARD AND 1:64 CAR STILL SEALED $2,500.00 |
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Forza Ferrari Magazine COMPLETE SET #1 thru #114 MINT Most Still Sealed $1,972.00 |
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SUNFIRE THEATER GRAND 5 PROCESSOR (STILL SEALED IN THE BOX) $1,800.00 |
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2003 DNA DOUBLE HELIX £2 TWO POUND GOLD PROOF COIN STILL MINT SEALED $1,699.95 |
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1999 RUGBY WORLDCUP £2 TWO POUND GOLD PROOF COIN BOX COA STILL MINT SEALED $1,699.95 |
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1995 UNITED NATIONS £2 TWO POUND GOLD PROOF COIN BOX COA STILL MINT SEALED $1,629.95 |
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1996 FOOTBALL £2 TWO POUND GOLD PROOF COIN BOX COA STILL MINT SEALED $1,599.95 |
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1992 GOLD PROOF £2 TWO POUND DOUBLE SOVEREIGN COIN BOX COA STILL MINT SEALED $1,579.95 |
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2009 CHARLES DARWIN £2 TWO POUND GOLD PROOF COIN STILL MINT SEALED $1,549.95 |
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2009 ROBERT BURNS £2 TWO POUND GOLD PROOF COIN STILL MINT SEALED $1,499.95 |
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2008 OLYMPIC GAMES HANDOVER £2 POUND GOLD PROOF COIN BOX COA STILL MINT SEALED $1,499.95 |
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2008 OLYMPIC CENTENARY £2 TWO POUND GOLD PROOF COIN BOX COA STILL MINT SEALED $1,499.95 |
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2007 SLAVE TRADE £2 TWO POUND GOLD PROOF COIN BOX COA STILL MINT SEALED $1,499.95 |
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2004 STEAM LOCOMOTIVE £2 TWO POUND GOLD PROOF COIN STILL MINT SEALED $1,499.95 |
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2006 VICTORIA CROSS HEROIC 50p GOLD PROOF COIN BOX COA STILL MINT SEALED $1,377.45 |
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2005 DICTIONARY 50p FIFTY PENCE GOLD PROOF COIN BOX COA STILL MINT SEALED $1,377.45 |
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2004 ROGER BANNISTER 50p GOLD PROOF COIN BOX COA STILL MINT SEALED $1,377.45 |
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2003 SUFFRAGETTE 50p FIFTY PENCE GOLD PROOF COIN BOX COA STILL MINT SEALED $1,377.45 |
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2009 KEW GARDENS 50p FIFTY PENCE GOLD PROOF COIN STILL MINT SEALED $1,329.95 |
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2007 SCOUT CENTENARY 50p GOLD PROOF COIN BOX COA STILL MINT SEALED $1,329.95 |
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SEALED Steve Hanks Signed Limited Edition Print Time Standing Still 869/999 COA $1,319.12 |
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NEW REMAN ALLEN-BRADLEY 2711T10C15/F 2711T10C15 SER F Still sealed in plastic! $1,199.99 |
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1998-S Lincoln Cent CLOSE AM variety STILL SEALED IN PROOF SET perfect key coin $1,174.00 |
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10 Republic of India Proof Coin Sets 1969 STILL SEALED w/ 80% Silver Coin E224 $1,025.00 |
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Is He Using You? by Allan Harris still sealed $995.00 |
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VINTAGE COCA COLA BOTTLE 1900′S STILL SEALED FULL!!!! RARE RARE RARE!!!! $899.99 |
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1997 BRITANNIA 10TH ANNIV £25 POUND GOLD PROOF 1/4oz COIN COA STILL MINT SEALED $899.95 |
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Mint in box still sealed iPhone 4 S 16GB in white Mobile smartphone MIB 2012 $830.95 |
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1997 GOLD PROOF SOLID 22K FULL SOVEREIGN COIN BOX COA STILL MINT SEALED $849.95 |
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1998 BRITANNIA £25 POUND GOLD PROOF 1/4oz COIN BOX COA STILL MINT SEALED $849.95 |
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NITTY GRITTY 2.5FI AUDIOPHILE HIGH END RECORD CLEANER–STILL SEALED IN BOX!! $799.00 |
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2000 BRITANNIA £25 POUND GOLD PROOF 1/4oz COIN BOX COA STILL MINT SEALED $829.95 |
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Toshiba 42″ Flat Screen TV, Never Used, Still in Sealed Box! $800.00 |
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1999 BRITANNIA £25 POUND GOLD PROOF 1/4oz COIN STILL MINT SEALED $799.95 |
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SUPERMAN Album Box – LP + Comic, 1966, still sealed $750.00 |
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GOOD NEWS II 2 (Keith Green, Bob Carlisle) 1977 ULTRA RARE STILL SEALED LP ! ! $750.00 |
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MAHLER 3.Symphony BERNSTEIN 1989 DGG DIGITAL 2LP – STILL SEALED $726.14 |
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BRUCE SPRINGSTEEN ULTRA & MEGA-RARE JAPAN ONLY 1992 PROMO ONLY & STILL SEALED ! $725.00 |
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THE BEATLES Wooden Box Collection 15LP MONO STILL Sealed BRAND NEW $640.71 |
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DEAD CAN DANCE – 9 x SACD BOX SET * RARE STILL NEW & SEALED $690.00 |
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BRAND NEW AT&T 64gb IPAD 2 WiFi + 3G……STILL SEALED!!!!! $660.00 |
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Apple iPhone 4S – 16GB – Black (Factory Unlocked) still sealed worldwide use $620.00 |
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Pink Floyd Meddle CD Gold MFSL Ultradisc I LongBox Japan Still Sealed SS $599.99 |
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1999 GOLD PROOF 22K HALF SOVEREIGN COIN BOX COA STILL MINT SEALED $599.95 |
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Hiller MSC2 NOS NIB never used still sealed very rare ! $575.00 |
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JOURNEY INFINITY SONY MASTER SOUND GOLD CD STILL SEALED $549.99 |
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1998 BRITANNIA £10 POUND GOLD PROOF COIN BOX COA STILL ROYAL MINT SEALED $549.95 |
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CHANEL Nº5 No5 VINTAGE PARFUM EXTRAIT 28ml 1 FL.OZ INCREDIBLY RARE STILL SEALED $506.24 |
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2005 GOLD PROOF 22K HALF SOVEREIGN COIN BOX COA STILL MINT SEALED $529.95 |
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Still SEALED Japan METALLICA $5.98 LP complete POSTER sticker obi 1987 original! $499.99 |
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QUEEN Japan PROMO issue 1991 12 x CD single BOX SET still SEALED Freddie Mercury $479.99 |
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THE BEATLES YELLOW SUBMARINE ORIGINAL APPLE LABEL LP STILL SEALED! $499.99 |
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ELVIS PRESLEY Orig. German Black RCA LSP-3702 LP STILL ORIGINAL TELDEC SEALED ! $499.99 |
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ELVIS PRESLEY Orig. German Black RCA LSP-3758 LP STILL ORIGINAL TELDEC SEALED ! $499.99 |
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ELVIS PRESLEY Orig. German Black RCA LSP-1707 LP STILL ORIGINAL TELDEC SEALED ! $499.99 |
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ELVIS PRESLEY Orig. German Black RCA LSP-1884 LP STILL ORIGINAL TELDEC SEALED ! $499.99 |
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Pink Floyd Wish You were Here CD Gold Mastersound SBM LongBox Still Sealed $499.99 |
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Pink Floyd The Wall 2x CD Gold MFSL Ultradisc I Japan Still Sealed SS $499.99 |
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BEATLES REVOLVER MONO ’66 LP STILL SEALED W/ PRICE STKR $499.99 |
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2000 BRITANNIA £10 TEN POUND GOLD PROOF 1/10oz COIN BOX COA STILL MINT SEALED $499.95 |
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Grateful Dead lp mega rare white cover Anthem of the Sun STILL SEALED near mint $499.00 |
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Allman Brothers MFSL Eat a Peach LP X 2 NEW and still Sealed $487.50 |
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BRAND NEW AT&T WHITE 32GB IPAD 2…..STILL SEALED!!!!!!!!!!!! $460.00 |
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1999 BRITANNIA £10 TEN POUND GOLD PROOF 1/10oz COIN BOX COA STILL MINT SEALED $479.95 |
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1996 BRITANNIA £10 TEN POUND GOLD PROOF 1/10oz COIN BOX COA STILL MINT SEALED $479.95 |
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1995 BRITANNIA £10 TEN POUND GOLD PROOF 1/10oz COIN BOX COA STILL MINT SEALED $479.95 |
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1994 BRITANNIA £10 TEN POUND GOLD PROOF 1/10oz COIN BOX COA STILL MINT SEALED $479.95 |
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Cezanne STILL LIFE Etching Ambroise Vollard Estate Seal $469.99 |
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2004 GOLD PROOF 22K HALF SOVEREIGN COIN BOX COA STILL MINT SEALED $469.95 |
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Yugioh Collectible Tins – set of 12 Tins NEW and Still sealed in plastic $420.00 |
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LED ZEPPELIN IV LP STILL FACTORY SEALED WITH STICKER $449.99 |
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DEEP PURPLE Fireball Japanese Gold CD Still Sealed ! $450.00 |
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PEARL JAM Ten RARE AS! 4 x 12″ Vinyl Record LP Box Set Still Sealed EDDIE VEDDER $374.38 |
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SIGNED 1st Edition Leather bound book-TIMEQUAKE by KURT VONNEGUT still sealed! $405.87 |
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20 PS3 Games in perfect condition! some still sealed!! $408.99 |
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BEATLES ORIGINAL HAIR BRUSH STILL SEALED W/ HEADER CARD $399.00 |
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BEATLES ORIGINAL HAIR BRUSH STILL SEALED W/ HEADER CARD $399.00 |
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ORIGINAL TITUS OATES JUNGLE LADY STILL SEALED PSYCH LP TEXAS PROG PRIVATE $399.99 |
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STILL SEALED ORIG LP~DOORS~SOFT PARADE~W/STICKER~on ELK $399.99 |
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STILL SEALED ORIG LP~NEIL YOUNG~HARVEST~TEXTURED COVER! $399.99 |
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Bo Diddley “Is A Lover” Orig. LP Still SEALED Very Rare Checker $399.99 |
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1987 Fleer Baseball Rack Case (Still Sealed) $379.99 |
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The Shining 15×20 Lobby Card Set Still Sealed $379.99 |
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Still SEALED Japan METALLICA LP MASTER OF PUPPETS original 1986 with obi! $349.99 |
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Austin Osman Spare Black Magician Occult Ltd Ed #13/125 Still Sealed RARE OOP $364.27 |
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EMPRESS OF THE GOLDEN BLOSSOM BARBIE STILL FACTORY SEALED IN SHIPPER PERFECT !! $349.99 |
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Hum: You’d Prefer An Astronaut. STILL FACTORY-SEALED. U.S.-Print. TIN-012 LP. $350.00 |
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Whitney Houston – OST. The Bodyguard, Korea Only Picture Disk. Still Sealed.1992 $350.00 |
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MICHAEL JACKSON THRILLER STILL SEALED UNOPENED 1982 $350.00 |
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Monopoly 1965 Blue Case 30th Anniversary Edition Still Factory Sealed $349.99 |
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BOSE QUITE COMFORT 3 BRAND NEW UNIT STILL IN SEALED FACTORY BOX $340.00 |
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1994 Upper Deck SP Baseball Wax Box – Still Sealed – Alex Rodriguez RC $325.00 |
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Sideshow LOTR Fell Beast vs Versus Eagle Diorama Statue NIB still sealed $300.00 |
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Brand New Apple iPod Nano 2nd Generation Silver (4 GB) NIB Still Sealed $324.95 |