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| [#1] 聽黑膠高音失真，請高手救命!!! 半年之前在二手區買咗套VPI TT + SME V + BPS II，播LP時發現在大聲高音時拆聲，以為唱頭到期，換咗隻17D3，一樣拆！已從頭set過幾次，包括唔同HTA, VTF, AS.....都唔得，請問有無C Hing知道咩問題？有咩我可以試？ 最後修改時間: 2011-01-03 12:17:22 |
bigpanda 正式會員116.xxx.xxx.135 |
2011-01-03 12:10 | |
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| [#2] 聽黑膠高音失真，請高手救命!!! 大聲高音時拆聲, 1係部Amp. or 係對喇叭. |
cornercube 正式會員 219.xxx.xxx.116 |
2011-01-03 12:49 |
| [#3] 聽黑膠高音失真，請高手救命!!! 先假設各部份運作正常， 從那個位置開始"拆"? 一開始? 碟尾呢? 之前那個頭重多少克? 如果也是5-6克，證明是唱頭太輕，要加spacer，約重2-3克的，再重set VTA及其它基本嘢。 在SME V，要改azimuth也只可在spacer墊上下功夫，最好不要"攝"臂座。 先聲明：本人不是高手。 最後修改時間: 2011-01-03 13:06:47 |
黃思璁 正式會員 119.xxx.xxx.230 |
2011-01-03 12:50 |
| [#4] 聽黑膠高音失真，請高手救命!!! 想多問一下你的情況，你是用什麼唱頭放大器、和唱頭的阻抗有冇 set 好，唱頭放大器的輸出和擴音機的 impeance/sensitivity是否配合。 |
laipat 正式會員 220.xxx.xxx.196 |
2011-01-03 13:15 |
| [#5] 聽黑膠高音失真，請高手救命!!! could be inherit problems of the tonearm. Maybe bearing problems! 拆聲 from azimuth problems likely concentrated when playing the last song! |
S6410 正式會員 61.xxx.xxx.157 |
2011-01-03 13:58 |
| [#6] 聽黑膠高音失真，請高手救命!!! 咁係咪隻隻碟都拆? |
ozrayyau 正式會員 122.xxx.xxx.194 |
2011-01-03 16:13 |
| [#7] 聽黑膠高音失真，請高手救命!!! 多謝咁多位C Hing回覆，我phono amp係DIY EAR834p，經Lundhal LL1931 MC牛，試過用第二隻MC牛同唔用MC牛，無論碟頭尾都拆，幾隻碟都拆，因為新舊頭都拆，所以應該不是重量問題。Amp 同喇叭聽CD冇事。 |
bigpanda 正式會員 116.xxx.xxx.135 |
2011-01-03 16:55 |
| [#8] 聽黑膠高音失真，請高手救命!!! 試下係唱殼上加spacer 或 2-3g 既weight，可先用小量blue tack 貼上。小弟用Shure M44G 拆到啊媽都唔認得，s 音爆到九彩，都係靠呢招攪掂。原理係乜我就真係唔識啦 .... 但實驗證明得左，就試試佢lor! 記住reset過唱重播！ |
simpson355 正式會員 203.xxx.xxx.225 |
2011-01-03 17:51 |
| [#9] 聽黑膠高音失真，請高手救命!!! Dear C-hing, May I know where the spacers are available? Thanks! Regards |
2262 正式會員 202.xxx.xxx.195 |
2011-01-03 17:59 |
| [#10] 聽黑膠高音失真，請高手救命!!! ＞＞＞因為新舊頭都拆，所以應該不是重量問題。Amp 同喇叭聽CD冇事。＜＜＜ 根據資料，最有可能仍是唱頭5.3g太輕了，最值得試的就是加多幾gram，加少少blu tack試就要用磅磅一下，check過SME V的effective mass是11/12g，可試用4-4.2克。 注意: VTF(針壓)不用加重，新頭仍用1.8-2.0克。 最後修改時間: 2011-01-03 19:02:33 |
黃思璁 正式會員 119.xxx.xxx.230 |
2011-01-03 18:55 |
| [#11] 聽黑膠高音失真，請高手救命!!! 如有電子磅，也可DIY，先試試work唔work，用舊的credit card自已剪，幾塊叠起... 重set VTA/azimuth，VTF/alignment不用更改。 注意：此法如用於膠唱頭，螺絲鎖得太緊，唱頭可能會裂，小心!!! 最後修改時間: 2011-01-03 19:25:54 |
黃思璁 正式會員 119.xxx.xxx.230 |
2011-01-03 19:25 |
| [#12] 聽黑膠高音失真，請高手救命!!! 先快速試試效果，可用blu tack。 4.2g原來都會幾大舊，磅時"初"圓佢，磅準後就"噤"扁貼於唱臂底，要"噤"時好實。 再重set VTF。 最後修改時間: 2011-01-03 20:11:17 |
黃思璁 正式會員 119.xxx.xxx.230 |
2011-01-03 19:56 |
| [#13] 聽黑膠高音失真，請高手救命!!! 親愛的黃思璁先生: 可否解釋 : "最有可能仍是唱頭5.3g太輕了" 你的理據是什麼? 為什麼要加4-4.2克？ |
frah 正式會員 202.xxx.xxx.12 |
2011-01-03 21:43 |
| [#14] 聽黑膠高音失真，請高手救命!!! Dear Frah兄 簡而言之，理由是SME V的effective mass(claimed as 11/12g)、唱臂物料、和Dyna 17D3的cart mass、compliance唔匹配，resonance的頻率不理想，唱針循跡會不穩定，無論怎set，聲都很易"折"，即是所謂"unhappy marriage"。 本人曾遇過類似情況，當時唱頭重量(5g)、compliance(15x10-6/dyne)和17D3幾乎一樣，最後要加spacer，將arm eff mass+cart mass+spacer總重至約20-21g(註:太重也未必行!)，問題就解決了(見圖的credit card殘骸)，手工差得很，但實驗成功! 要聲不"拆"，加spacer(mass)算是其中一種最便宜的方法，另一種更便宜(?)，就是「唔聽」。 這方面其實網上有很多用家例證，廠方/音響雜誌則好像很少提到(商業決定/唔識? 不得而知了...)，除了Van Den Hul及Reed，很值得大家去看看。 之前Typo:...(blu tack)要"噤"得好實。  最後修改時間: 2011-01-03 22:42:44 |
黃思璁 正式會員 119.xxx.xxx.230 |
2011-01-03 22:35 |
| [#15] 聽黑膠高音失真，請高手救命!!! Photo  |
黃思璁 正式會員 119.xxx.xxx.230 |
2011-01-03 22:36 |
| [#16] 聽黑膠高音失真，請高手救命!!! Thanks 黃思璁 C Hing Will try in the next few day and advise you the result. Thanks for all C hing's advice. |
bigpanda 正式會員 221.xxx.xxx.211 |
2011-01-03 23:04 |
| [#17] 聽黑膠高音失真，請高手救命!!! 說來慚愧，香港剛有一位偉人去世... 手頭上的問題已全部回覆了，暫別大家一會，Good Luck!!! |
黃思璁 正式會員 119.xxx.xxx.230 |
2011-01-04 00:11 |
| [#18] 聽黑膠高音失真，請高手救命!!! Agree with 黃思璁, effective mass and compliance maybe one of the root cause. For the spacer, I use this one that designed and produced by my friend featuring isolation spikes for enthusiastic setting.  |
Vash 正式會員 219.xxx.xxx.250 |
2011-01-04 01:32 |
| [#19] 聽黑膠高音失真，請高手救命!!! Cartridge / Arm Matching....or things you didn't really want to know about resonant frequency of a system tonearm/cartridge which is coupled to the record by the compliance of the cantilever suspension. ... 1) above photo #1: showing the cantilever and location of suspension. The suspension element may be as simple as a tight fitting elastic grommet that grips both the shaft and the cartridge body. 2) above photo #2: Showing stylus mounting in the cantilever. This is a nude mounting that features a precise 'force fit' between stylus body and the bore in the cantilever. Additionally, a small bit of adhesive is applied over the joint to ensure a lasting fit. side note: Whoever said "diamonds are forever" was not referring to phono cartridge stylii. They wear out. Yet, like their jewelry counterparts, they are expensive nonetheless. Matching a cartridge to a tonearm (pivoting tone arms) The focus here is upon elements of the cartridge design, and elements of the tonearm design which affect how a vinyl addict might go about choosing a given cartridge to fit a given tonearm. First, some definitions. Effective mass versus compliance results in a Resonant Frequency (of the cantilever) Compliance: Let's take a look at a spring (any spring) designed to carry a given load. Place too much weight on this spring and it collapses. Place not enough weight on the spring and the spring won't compress at all and remains rigid. Think of the cantilever as a spring. In the case of a phonograph cartridge, the cantilever is a rigid arm connected to a springing medium mounted up within the body of the cartridge. This springing element may be as simple as a rubber donut that holds enough tension against the cantilever mounting to maintain relative position of the cantilever. Most importantly, the suspension must control the attitude of the stylus fitted at the cantilever's end. The amount of distance that a cantilever deflects under a given force load is referred to as cantilever compliance. Higher compliance cantilevers deflect a greater distance when a given amount of force is applied. Lower compliance cantilevers deflect lesser distances when the same force is applied. In other words; high compliance = softer, low compliance = stiffer. Vertical Tracking Force (VTF): The amount of vertical force placed upon the cantilever is controlled by a careful balance between the weights of the arm on either end of the pivot. Typically, the tonearm will have a long tube leading to a head shell with a phonograph cartridge and stylus at that end. The other end of the tonearm will have weights intended to balance the mass of the long end. By careful manipulation of the counterweight position, relative to the distance from the pivot bearing, a precisely measured amount of vertical force may be applied at the stylus end. Effective Mass: The amount of force felt at the stylus under dynamic conditions in any (xyz) arcing vector about the pivot. This differs from VTF which is set static and remains constant only under 'peaceful' conditions while the record is in play. Effective mass is influenced by the weight of the various appendages of the tonearm assembly in ratio to the distance from the pivot. Weight that is further from the pivot center will account for higher effective mass than the same weight if positioned closer to the pivot. Said slightly differently, the heavy bits on the tonearm need to be closer to the tonearm pivot or excessive effective mass will be the result. Phonograph cartridges have different weights from one product to the next, therefore tonearm makers rate their arms in terms of effective mass before a cartridge is mounted. In the case of the SME 3009 Improved with fixed head shell, the arm is rated to have an effective mass of 6.5 grams. Compare this to the Thorens TP16 Mk 1 tonearm which has a rated effective mass of 16.5grams. Resonant frequency of the cantilever is used as a guide to match suspension stiffness (compliance) of the cartridge to the tone arm's (effective) mass. Resonant Frequency (of the cantilever) The acoustic frequency at which the cantilever will become excited and vibrate out of control. :))) This frequency is measured in cycles per second. Also referred to as 'hz'. Resonant frequency of a cantilever is regarded as inescapable and the effect is controlled by manipulating this frequency to exist in a range below human hearing but not so low that it will become excited by external vibrations such as foot fall disturbance or that of a warped record. This ideal frequency range is 8 to 12 hz. The lowest of low organ notes rarely go below 20 hz. Footfall and record warps happen below 6 hz. The effective mass of a tonearm in combination with the compliance of the cartridge cantilever serves to determine where the resonant frequency of a given tonearm/cartridge match up will be. In general terms, arms with high effective mass fitted with cartridges of high compliance result in resonant frequencies that fall below the ideal range. At the opposite end, arms with low effective mass mated to cartridges of low compliance result in resonant frequencies above the desired range. Both extremes are to be avoided. So....wouldn't it be useful if you could calculate a resonant frequency between a given arm and cart...? You can, just plug in some vital statistics into the short formula below. Keep in mind the formula is intended as a rule of thumb. The test record will be the final say on what a given arm cart combo can give in terms of cantilever resonant frequency. Think of the formula as a 'on paper test' and the test record as a 'real world actual test'. rf = 159 / sqrt ((eff. mass + cart weight + fastener weight) * (compliance)) rf: resonant frequency in hz eff. mass: rated by tonearm manufacturer cart weight: rated by cartridge manufacturer, but if accurate scales exist, an actual weight value could be used fastener weight: screws, nuts, spacers, washers, shims. They have weight and add to the mass over the stylus compliance: rated by cartridge manufacturer Freek's Resonant Frequency Calculator a short Excel spreadsheet that simplifies using the above formula. MS Excel required. Example No. 1: Now let us think about matching a Shure V15VxMR to the above pictured TP16 Mk 1 tonearm. effective mass rating: 16.5 grams cartridge weight: 6.6 grams fastener weight: .5 grams compliance: 25 (16.5 + 6.6 + .5) * 25 = 590 sqrt 590 = 24.2899 159 / 24.2899 = 6.5459 hz calculated The above figure was approximately verified with the HFNRR test record getting a test result value of 6 hz I'll admit that I have lived with the above combination for a time. I found the setup susceptible to footfall but it seemed to track record warps just fine. A marginal matching. It is the wrong side of marginal, too. Another visual note about this match-up is that the high compliance of the Shure cantilever was quite obvious when dropping the stylus into the lead in groove. Considerable sideways deflection was evident. This is not the same case with the above match up between the Shure and the much lighter SME tonearm. For more notes about The Shure cartridge and it's dynamic stabilizer when fitted to the TP16 mk 1 see the ** below. Example No. 2: with the TP16 Mk 1 tonearm. This time with the above pictured Blue Point Special cartridge...? Let's crunch the numbers and see. effective mass rating: 16.5 grams cartridge weight: 9.0 grams fastener weight: .5 grams compliance: 12 (16.5 + 9.0 + .5) * 12 = 312 sqrt 312 = 17.6635 159 / 17.6635 = 9.0016 hz. Example No. 3: let's calculate the rf for my SME 3009 Improved Fixed Head shell tonearm and Shure V15VxMR cartridge. The effective mass rating for the arm is 6.5 grams The weight of the cartridge is rated at 6.6grams fastener weight: .5 grams Compliance is rated at 25 (x 10¯6 cm/dyne)* (6.5 + 6.6 + .5) * 25 = 340 sqrt 340 = 18.4391 159 / 18.4391 = 8.6230 hz calculated HFNRR test result: side 2 band 2 low freq. horizontal resonance test......10 hz Notes about the discrepancy between the test record figure and the calculation. The test record value is considered to be the valid reference. One of the variables in the calculation must be incorrect. Perhaps effective mass rating of the tonearm may actually be lighter in the real world situation. The finger lift was not used and so does not contribute to the effective mass. I have no accurate means to measure the weight of the finger lift. I used the shortest possible screws in the cartridge mounting. Said screws and nuts are aluminum. How to calculate Compliance based on a Test record result for resonant frequency: C = 25330 / ((eff mass + cart mass + fastener weight) x (rf squared) Example: Denon DL103R cartridge mounted to an Expressimo modified RB250 approximate effective mass of the Expressimo RB250: 10g cartridge weight: 8.5g fastenener weight: .5g test record lateral rf result: 11 hz ((10 + 8.5 + .5) x 11^) or 19 * 121 = 2299 then 25330 / 2299 = 11.0178 (compliance) *Shure does not publish compliance figures for this cartridge in the owners manual that comes with it. A search of the knowledge base at the Shure website turned up the following information on the V15VxMR: Compliance rating (dynamic): 25 x 10^6 cm/dyne recommended (for best performance) tonearm effective mass: 6 to 12 grams Shure Knowledge Base (link for more info) ** : The Shure V15VxMR phono cartridge uses a device that Shure calls a "dynamic stabilizer". They (Shure) describe this device as a shock absorber for their cantilever. If this device is put to use, it is claimed that a much wider range of effective mass tone arms may be used with this cartridge. I have used this 'dynamic stabilizer' when the cartridge was fitted to the heavy TP16 mk1 and found that the cartridge tracked all records without any apparent fault. When the device was parked in it's 'up' position (taken out of use) a much greater amount of cantilever deflection could be witnessed and the tonearm was more susceptible to external disturbance. The 'device' was not put to use with the SME tonearm as the resonant frequency of the cantilever falls within the optimal range when fitted to this arm. *** : All math/physics formulas and explanations offered on this page were either collected from or donated by persons more capable and knowledgeable than myself. I just operate them. If you see an error or have another formula useful to this topic please contact me. |
BillySIU 正式會員 202.xxx.xxx.21 |
2011-01-04 08:41 |
| [#20] 聽黑膠高音失真，請高手救命!!! Photo 1  |
BillySIU 正式會員 202.xxx.xxx.28 |
2011-01-04 08:44 |
