请教REVOX PR99属于什么档次，谢谢！

红灯记

线速度恒定，角速度随带半径的变化而变化，半径大角速度小...

zmw5777

1400欧也就一月薪水按国内讲不贵。

zox

tempo 发表于 2013-2-22 16:25

                               
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0 U" L8 k4 }0 m+ b10寸带越听越慢肯定有问题，要不就是大小盘开关位置不对。我有两台pr99都没这问题。

越听越慢是以严格的标准要求的，你用pr99录一整场交响乐，到后面肯定不行。
就是专业机70年代，例如ampex 440,在使用中还是发现问题，录音到后面会变慢，所以，超过10分钟的节目就不能录了。但一般的流行歌曲也就3，4分钟。
民用里，revox 270解决了这个问题。但其实270也算半专业了。

红灯记

zox 发表于 2013-2-23 11:33

                               
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越听越慢是以严格的标准要求的，你用pr99录一整场交响乐，到后面肯定不行。
就是专业机70年代，例如ampe ...

8 K+ A8 Y# \6 v+ S" L+ v( q' s" |如tempo所说，你的机器的确有问题{:4_230:}

zox

我不知道怎么称呼这个，就是保证速度的这个，叫： 张力伺服？

zox

constant torque transports＝ pr99 ,a77 ,ampex 440

BARTONM46

商业的开盘带， 内径大， 不满盘， 是否是这个原因？

红灯记

tempo版的试验与模拟录音机测试指标中的抖幌测试方法类似，原理是一样的，只不过标准的抖幌测试频率采用的是315Hz正弦波信号：录制重放后的频率与实际输入的315Hz的差值△Hz与315Hz的百分比，以此衡量传统模拟录音机走带系统的稳定性，建议TEMPO版用这个频率试试{:4_214:}
另外，万用表读数的1hz误差也可能来自万用表本身量化的误差，3949Hz已经在其读取量化频率域的最上限，高于3949Hz或者3950Hz的频率万用表无法准确的直观显示，直接影响到您试验的准确性，如果不采用315Hz，用1000Hz做实验也足以说明问题了，经验告诉我，任何测试仪器，测试域的最高端与最低端附近的准确性是最差的。
: P- P& M' k+ {1 `; k/ b拙见供参考，元宵节快乐{:4_223:}

zox

tempo版主的实践精神值得大家学习，从现在的测试结果来说，pr99是很好的。

zox

从录音界的实际使用情况，大家普遍反应是这样的，ampex440录音不会超过10分钟的。
我摘抄一小段，不过，我想事实胜于一切，道听途说就是一个参考。
/ ~# }3 [' F  e/ n5 k" A
/ ]; c# L5 j' _0 G. g, UI maintained tape machines at a radio station for about 10 years (1986-96) until analog almost went away. Here are a few of my thoughts from that experience.

) {0 a: U5 X2 U4 }" o& N4 zAmpex:

' t  K+ |7 |( O- g1 cWe had a selection of AG440B and C models in 1986, which were gradually being phased out. They are very simple machines, and built like tanks. They did have fairly frequent failures (electrolytics were getting old, and I remember having a supply of 2N3904 transistors), but as someone else noted, fairly easy to fix once you get used to them. They are constant torque transports, so they slow down at the end of a reel. There's nothing you can do about it. Even the DC servo capstan option will not help. Wow and flutter was OK but not remarkable, possibly made worse by the age of the machines. I had a retired 440C, but gave it away to a retired announcer who had some old tapes he wanted to play.
# v! Z& {' Z) N. K
There were still a few old mono 300, AG 350, and 351 machines around, but they have basically the same transport with the same shortcomings.
Revox: We had a few A77 and PR99 machines, but they have a simple constant torque transport as well, so they don't have any speed stability. I would reject them, the same as the 440s.
8 y! q! z. u2 {5 k) ^) T+ M1 _
' ^; u2 _. L) E# A

tan1122

好文章。学习了。tempo的实践精神值得学习。

BARTONM46

也就是说， 走带， 不管是放音还是录音， 速度有主轴电机决定， 放带电机和收带电机顺从主轴电机。