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Rosa,你好！ 高兴见到你出现！！！
上面的连接我做个简单的翻译：
http://members.myactv.net/~je2a3/open.htm
As many of you know I am an openbaffle advocate and have used the 755A and 755C in this concuction for years. However, I recentlyattended a radio show event after a few years of hiatus and saw my friend ChongOng. He handed me these ~ 2 cubic foot "homebrew" sealed boxesdesigned for use with the 8" WE/Altec 755 speakers. According to him thesecabinets were acquired from a retired WE engineer which encouraged me to givethe sealed box enclosure another chance.
我推崇障板和使用755A多年，估计众所周知。
不过最近，最近参观一个几年没去的电台展，遇到老友Chong Ong。他给我看他的2立方英尺的“私用家伙”密封箱，使8”西电和Altec755 的专用的设计。据他说这两个箱体是他从退休的西电工程师手里接收的，呵呵，这引起我对这个密封箱的莫大兴趣。
In the past I have experimented with two types ofslanted 2 cu. ft. enclosures - an original Altec618 and custombuilt 622 using 1/2" plywood - and always endedup with mixed results. The above cabinets look like the 618 and the dimensionsare - 22"H x 17"W x 10 1/2" top depth x 13 1/2" bottomdepth - using 5/8" plywood instead of the 1/2" used in the originalAltec 618 Utility cabinet. The panels are lined with ancient type of dampingmaterial known as "Kimsul", which reminds me of crepe paper. I haveseen this material inside Western Electric 753 and 757 loudspeaker systems andeven as wrapping material in old tube boxes.
过去我用过两个2立方英尺、8分5英寸厚夹板、斜面板的箱体-原装Altec618 和特造的622，得到多种不同的经验。上图貌似618，尺寸：22高 x 17宽 x 10.5顶深（底部深13.5）（英寸），板后5/8 英寸二并非原Altec618的0.5 英寸。
所有板都用古董的吸音物叫“Kimsul”，一种看似皱纸的材料。我在西电的753 和757都见过，也在一些管结构的箱子看过。
The first driver I tried was the 755C but these observations were alsovalidated when I installed the 755Aand 755E. Compared to the open baffle, this cabinet gives an impression ofquicker transients and dynamic nuances which Joe Roberts call "snap"which I could never achieve from dabbling with the 618 and 622. My mainfrustration when I experimented with the aforementioned cabinets was, bothsounded slow in spite of the many tricks I tried - walls lightly damped withpillow stuffing [Dacron] , bare "lacquered and resonant" panels andetc.
我先试做755c，这个观察对于755A和755E都合用。
与障板比较，这个密闭箱感觉瞬变更快，动态鲜明，正如Joe Roberts 说的“快闪”，
我磨改过的622 和618都不能做到……最令我菹丧者，两个dd我多方折腾磨改，都觉得慢---所有板壁都用枕头棉阻尼，板面只加清漆的自由共振等等。
Anyway, along with the "snap" comes a moreforward soundstage presentation. There is a bit of a midbass hump in the 90-120hz region reminiscent of an LS 3/5A,most evident with the 755Cand 755E because they extend lower in the bass. Bass aficionados will probablyprefer this cabinet over an open baffle because of this sonic illusion. Butremember that even with open baffles, there is not much solid bass below 60 hzon any of these drivers. For that matter I never heard a modern high-endspeaker with an 8" woofer that can go down flat to 50 hz and still possessa lucid midrange like these vintage units. The midbass bloom is less obviouswith the 755A andoverall this was the best sound I got from this box.
无论如何，与这个“快”一起来的，是较为前的音场。在90-120Hz有点峰是我记起LS 3/5A，在755C及755E更明显因为他们低频下潜较深。低音狂大概会因此爱死这个箱而不要障板。再者，即使是障板，这些单元在60周以下，也是一点点比较软乎乎的低频。
在低频这一点，我没有听过HiEnd 的8”的低音单元可以平直下潜到50Hz又能做到这几个单元的清晰的中频。在755A，中低频段没有“隆隆”，整体表现是在这个箱体做到的最好声音。
Even if the "pancakes" are claimed to goup to 15khz, they sound like the highs begin to drop slowly around 9khz whereasthe 755A stillhas some energy past its 13khz limit. This may be a psychoacoustic phenomenongiven that the pancakes have been redesigned to extend almost an octave lowerand lost the "exotic" cone chemistry of the 755A which brings out the even more glorious midrangeand silky highs. As many of you already know specs really do not mean much inreal world conditions.
即使这些“煎饼”
说能做到15KHz，听起来在9000周也开始滚降，唯有755A仍然在13KHz有点感觉。这个可能是心理作用，因为他们说755A是从新设计往下延伸多一个频程（低8度音符）会导致“音盆化学效应”消失连带影响美妙中频与丝绸感的高频。各位老烧都知道测试数据根本与声音表现没多大关系。
The lack of high frequency extension in the"pancakes" is more apparent in the 2 cu. ft. box and I was compelledto use a super tweeter. The Altec3000 is a natural choice but since this is hardto find and pricey I found the FostexFT-17H as an excellent and modestly priced[$70/pr.] alternative. I use a 1uf oil filled capacitor and an 8 ohm attenuatorto hook up either tweeters to fill-in the drooping response above 10 khz onthese drivers. With the 755A,I did not deem it necessary to use a super tweeter. Even the"ribbon-like" Altec 3000 can diminish the purity of the highfrequency abilities of the 755Aif not attenuated and crossed over properly. If you insist on extending the 755A's, I can only recommend using the 3000with a .5uf oil cap and attenuated judiciously.
高频的损失在2立方英尺的箱体较为明显，所以我必须加高音单元。用Altec的3000是自然之选但太难找又贵，就用了不太贵的Fostex的FT-17H。我用了个1uF油泡电容再串一个8欧电阻来调整10k以上的声量，但不觉得755A要用超高。如果高频单元减降不合理，即使“像丝带样的”Altec3000 也会把755A单元的高频纯净度降低。当然，假如你坚持要做高频延伸，我只能建议用3000 加0.5uF油泡电容，另精选电阻值。
When I designed the JELSE300Bdx, my only reference speakers were the 755Asand 755Cs in open baffles. The 755As can tend to sound peaky if driven by abrighter sounding amplifier or source component while the 755C and 755E are more forgiving. In terms of"apparent" sensitivity/efficiency, the 755C has a slight edge over the "A" and"E". In my 12'W x 15'L x 7.5'H mainlistening room, I need SE300B power to enjoylarge scale symphonic music with the 755A and 755E. With the 755C I can get by with an SE2A3 amp. However this does not prevent me from usingmicrowatt SE71A forlistening to small scale music on any of these drivers.
当我设计JEL SE300Bdx时，我唯一的参考声箱是障板的755A和755C。用较亮的功放或元件，755A感觉会有某些峰但C和E宽容度较好。在效率方面，C比A和E高丁点。在我的12宽，15长，7.5高的主听音房，我需要单端的300B功率推A和E来享受大编制的交响。但是C就可以用单端2A3。不过我也会用微功率的单端71A推这几个dd听小乐队。
Like I said in my SP17homebrewer article, the 755/OB combination remindsme of the Quad ESL57 with greater dynamic range and sensitivity. This 2 cubicfoot box is like an LS 3/5Awith a larger soundstage presentation, greater dynamic contrasts and SPLswithout the "bextrene" coloration in the mids. If you like planarspeakers, the open baffle will yield flatter bass response, even biggersoundstage, provide more depth and airy spaciousness at the expense of"snap". But if space is at a premium, you can achieve an "SEamp" friendly speaker system with BBC nearfield monitor quality from this2 cu. ft. enclosure with the 755Aand the 755C/755Ewith an Altec 3000 or Fostex FT-17H super tweeter.
我在SP17“音响私房菜”里面说过，755 障板给我ESL57 的静电感受而且动态更大。这个2立方英尺的箱体是能有更大声压更多动态的LS3/5A却没有“bextrene”塑胶味中音。
若你喜欢平面喇叭，障板可以有更大声场，更平直的低频，更深的舞台和更宽松的空气感但稍微慢。但如果大听音空间难求，就用喜欢单端的喇叭如这个2 立方装A、C或E，加Altec300听这个一如BBC近场监听音色的组合吧。
Below is a sketch of thisenclosure's external dimensions
Building tips:建箱的小提示：
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Use 5/8" cheap plywood, the more resonant the better, 1/2"slows down the sound from my experience
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用5/8”夹板，越多共振越好，用1/2”我试过，声音会慢
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Do not use MDF, this was not a known cabinet material to the designers ofthe 755 and other vintage drivers, anyway it is a sure fire recipe for disasterwhen using any vintage driver
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不要用中密度板，当时755时代的设计师没见过这个料，放在古董单元肯定让你好看。
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Front mounting will probably lessen the midbass bump and the darkermid-range tonality of the "C" and "E" but make sure thatthe driver is "routed in" so that the front of the speaker frame isflush with the baffle which will provide enough space at the rear for sound toexit through the small holes at the back of the speaker frame
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前面装进去会令C和E中低频起峰，中频稍暗，要嵌平在障板上，单元后面的单元就可以通过框架后面的小洞洞更自由的呼吸
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If the driver is front mounted, it is no longer necessary to have a"screw on" front or back panel, this way the cabinet will be tightlysealed
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前面装进去就不需要用螺丝上紧，箱体也极度密闭（henry按：不明白如何固定单元了）
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I have no source for Kimsul but reckon that Dacron polyester fill will bea decent substitute, just line the walls with 1- 2" of this stuff and itshould be fine
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我找不到皺纸，但猜想枕头棉可以替代，用1-2”就好
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发表于 2010-7-15 00:28
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