浅谈lp臂的调整，第一部分。 [复制链接]

现在有有问题了，如果唱头被唱头架挡住了垂直视线，无法完全看到唱头的边缘怎么办？只能从两个螺丝槽位置看到一点唱头边缘。

66mm和121mm的零点是通用的吗，可是我在网上看到每种唱臂的数据好像不太一样，这两点能通过数学公式推算吗，比如我的臂有效长度245mm超距14mm补偿角20。5度，能推算出两个零点吗？

>>66mm和121mm的零点是通用的吗，可是我在网上看到每种唱臂的数据好像不太一样，这两点能通过数学公式推算吗，比如我的臂有效长度245mm超距14mm补偿角20。5度，能推算出两个零点吗

不能用在10，或12"臂上。如你要算得话，可下载这个Excel 文件。http://www.enjoythemusic.com/Baerwald-Lofgren%20B.xls。我帮你算了一下是59.3mm, 112.2mm。

Hi Wang,

I think it's because the spec he gave is 比如 and not the actual data. A 12 in arm will have optimal offet 17.8 degree and overhang 13.4 mm  and null points of 66 and 121 if you want the lowest peak distortion. The 59.3 and 112.2 you got is only due to the fact that the data he gave is unrealistic and the calculator tries its best to evaluate a set of null points for this set of 比如 data which gives the lowest peak distortion for this  比如 data.
If you try the data I listed above, you will have the lowest peak distortion and the null points are located right at 66 and 121 and there are no other 比如 data which can give you even lower peak distortion.

Happy listening.

英雄惜英雄啊：）

stepinsh 在 2004-9-27 23:24:53 发表的内容 66mm和121mm的零点是通用的吗，可是我在网上看到每种唱臂的数据好像不太一样，这两点能通过数学公式推算吗，比如我的臂有效长度245mm超距14mm补偿角20。5度，能推算出两个零点吗？

The inputs to Baerwald and Lofgren equations are
1) Effective length
2) Inner most grove (60 according to IEC spec)
3) Outer most grove (146 according to IEC spec)

Now for each effective length an arm designer chooses, there will be a set of optimal overhang and offset angle which will be calculated from these equations so that the null points will be at 66 and 121 mm (Baerwald).

That means no matter if the arm is 9 in, 10 in, 12 in the null point is always at 66 and 121 mm if you calculate by Baerwald which minimizes the peak distortion at the outer and inner grooves. It's the overhang and offset and offset angle which changes when you change from 9 in to 12 in... Most arm designers will stick to this formula when he designs an arm and that's why you should see for 9 in arm, overhang at 18.2mm and offset angle of 22.1 degree.

If you figure out that your 9 in arm has different spec from above, it's likely that the designer either:
1) Used Lofgren's equation which minimizes the average distortion across the whole disc instead of the peak distortion at the inner and outer most groove.
2) Did not stick to IEC spec of outer and inner most groove since IEC spec is a very old spec dated from the age of 78 rpm and nowadays most LP do not have music band engraved as far as 60 mm.

http://bbs.hifi168.com/Bbs/article.asp?titleid=57587&ntypeid=10

JWang, leslie,

I am not 高手 at all. Just that I'm very anxious to know all the theories behind these turntables, arms design. I am now doing research on the pros and cons of belt drive TT, the pros and cons of using strong/weak motor.....

You see, LP setup is so much more fun than digital

Wayned,

I have a whole bunch of arm data at home, more than those listed on your link. Some of them are quite different. I shall check later. Most Japanese arm designers like to use null point other than 66 and 121 whereas European and US designers try to stick to the spec.