本帖最後由 ADA 於 2013-6-24 17:25 編輯
KK師兄, 有時玩得這類高溫膽其實只要提供足夠散熱空間或者長時間在冷氣環境下使用是可以很長壽的,
正如用 845 的用家, 熱到無可能唔開冷氣聽的.
但說實話, 如果想聽細緻的音樂, 這類大功率膽一定畀唔到樓主.
Ching見笑了，可能你覺得我半年就話要換膽有點誇張，覺得我用得好粗。
其實是個人容忍度問題，我通常好少頂到一支已經能力開始下跌既膽唔會好耐，我無測膽器材，全用耳作準。我估計我用膽唔會超過5成，大概佢開始失去動態既時間我就會換，因為到你聽到佢開始衰聲，佢之後就會更快地差落去。而一支全新的膽，比一支半新的膽效果差太遠了.....
ADA 發表於 2013-6-24 17:20 static/image/common/back.gif
KK師兄, 有時玩得這類高溫膽其實只要提供足夠散熱空間或者長時間在冷氣環境下使用是可以很長壽的,
正如用 8 ...
在下初階求學吹水階段,祗是麽著石頭過河,我想SEALTEAM4 兄的 LM219AI (845) 會遠熱過 LEO25兄的MP501(KT120).
用KT88 的工作點在KT120 胆上,好處是 大把HEADROOM, 足使高低音伸延,而中音細致比美EL34, 呢個就係出面的潮流以KT88線路.用KT120胆, 唔好處就–如ADA兄所列三點.我見多人試過後,同聲話决不翻扌界 KT88.似乎廠家同用家,正在以對腳來投KT120 一票.
咁請問美國原點TIA-260 呢部機玩唔玩得到120呀?
技術規格
輸出功率
最低正弦波連續平均輸出功率每
通道，兩個通道的操作是：
6 0瓦到 4歐姆負載
6 0瓦到8歐姆負載
額定功率帶
20Hz至20,000 Hz
總諧波失真
最大總諧波失真在任何功率水平從250萬瓦的額定輸出功率為：
0.5％為4或8歐姆負載
頻率響應
+0，-0.5分貝從20Hz至20,000 Hz
+0，-3DB從10Hz至50000赫茲
感性
最高等級：2.5V額定輸出為450mV
功率放大器輸入：2.5V，額定輸出
希客 發表於 2013-6-25 08:30 static/image/common/back.gif
在下初階求學吹水階段,祗是麽著石頭過河,我想SEALTEAM4 兄的 LM219AI (845) 會遠熱過 LEO25兄的MP501(KT1 ...
可惜 MP-501 講唔到比人和 KT120 同 KT88 究竟有咩分別，因為 MP-501 莫講話 KT88，連 KT90、KT100 都唔用得，好難搵到到一都機可以好肯定咁安全地、或者應該話可以令大家零争論咁只係同場比較 KT88 同 KT120。。。。。 唔知遲下有冇廠搞部有 KT120、KT100、KT90、KT88 seletor 嘅 amp，咁就好玩啦！
Wilmer威馬 發表於 2013-7-22 00:26 static/image/common/back.gif
可惜 MP-501 講唔到比人和 KT120 同 KT88 究竟有咩分別，因為 MP-501 莫講話 KT88，連 KT90、KT100 都唔 ...
馬爺！rogue audio嘅機咪可以囉！{:6_183:}
Wilmer威馬 發表於 2013-7-22 00:26 static/image/common/back.gif
可惜 MP-501 講唔到比人和 KT120 同 KT88 究竟有咩分別，因為 MP-501 莫講話 KT88，連 KT90、KT100 都唔 ...
"It is safe to use Tung Sol KT 120 in ALL Prima Luna amplifiers". Prima Luna 的Dialogue 5 係 auto bias, 本身以經可用EL34, KT88, KT90 及6650整 係列互用, 正如前文講, 最主要看POWER SUPPLE 可否乘受比KT88 多少許發熱電量, 而用120的好處是 UltraLinear 的class A 輸出會多咗, 更線性.有人用Electro Harmonix胆作 loadline 分析, 得出以卞結註論.
Real benefits of KT120 would be most possible for where LOW power is desired for hi-fi
and where clipping will never occur, and the power is nearly all pure class A. The maximum pure
class A possible from any two beam tetrodes or pentodes is about 45% of the total Pda at the
idle condition, so that if two KT120 are used with Pda at a safe 40Watts each, Pda total = 80W
and max class A PO = 36W, and this is substantially above a pair of KT88 with safe Pda total = 60W,
and class A PO max = 27W.
For class A, RLa-a is always higher than for class AB, and maximum peak Ea swing will always be a
high fraction of Ea. Peak Ia swing in the class A amp is never more than twice the idle Ia.
With the class A idle Ia set higher than for class AB amps, the gm at the operating point is both
higher and more constant, resulting in much more linear operation. Screen supply voltages seldom
need to be higher than +300V, and this allows lower g1 bias voltages easily generated using cathode
biasing with R&C networks between cathode and 0V, and without wasting much power in hot running
Rk. The class A tube has high voltage gain because gain = gm x RL (approx) and where local CFB is
used as in the Acoustical mode ( like Quad-II ), remarkably linear operation is gained.
For example, consider KT120, Ea = Eg2 = +400V, Ia = 100mA, and RLa-a = 5,600 ohms.
Peak Va swing = 360V, and PO = 46W, AB1, with the first 28 Watts in pure class A1.
The loadline analysis shows the 60W Pda limit line for KT120 well above the class B load line
of 1,400 ohms, so there is no risk of tubes overheating. Even if the load is reduced to 2,800 ohms,
max AB1 PO = 68W, and there is still no risk of tubes overheating. From this it is possible to use
KT120 at an idle Pda = 40W reliably so that Ia = 100mA, Under such conditions, distortion is
minimized, and music may sound much better than if the amp were set up with Ea at +550V, and
Ia at idle of 50mA, and RLa-a = 2k0, and class A max = 2.45Watts
http://www.turneraudio.com.au/loadmatch5-beam-tetrodes-about.html
CHING 入左KT-120未? 在那裡可買到?
lampard 發表於 2013-7-22 09:21 static/image/common/back.gif
馬爺！rogue audio嘅機咪可以囉！
有咩？
玩KT120有度好, 就係吾洗換旦, 因為得一個牌子 {:1_263:}
