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| [#23] 前石後膽怕燒機嗎 開關前後級次序係主要 |
Yatchboats 會員219.xxx.xxx.5 |
2021-06-20 11:03 | |
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| [#22] 前石後膽怕燒機嗎 ＞你很玄,你常常用問號"?"來結尾,究竟是譏諷?或不懂? Asking questions on things that I don't know or understand is my way of learning, especially when it seems to be illogical ＞1.胆前阻抗(impedance)如和石後不match,就算無signal/冇開volume,你對低音單元會自動出出入入。 A woofer moves only when there is current going into it. When you can actually see the in/out motion of a woofer, it means that a sub-sonic signal is being fed into it. The only logically explanation for such motion without any signal is that your system is oscillating and has nothing to do with impedance mismatch. What you were told was as ridiculous as saying a car's engined blew the gasket because the radiator hoses were changed (actually, someone did tell me that B-) ＞2.支膽在on/off時,會有直流DC,如你件石後是極品----(極品石後通常在放大線路上不用電容,因為電容會過濾signal)-----non-capacitor coupling,就會燒機。 That is possible even for solid state preamps. That is why one should leave the preamp on 24x7 if possible, for the sake of reliability and optimal operating state for the preamp. ＞但如你的胆前是有輸出牛(output transformer)設計 eg. Audio Note, Modwright, Ayon........就無問題,可以用乜石都得。 Of course, when a preamp has an output transformer, any DC drift is decoupled from the power amp. ＞以下是download KRELL 綱頁的warning: ＞... long warning removed ... It is interesting to see a mega buck power amp was NOT designed to handle DC in the input. I would say that someone under engineered the protection circuit and shifted the responsibility to the consumer. It is like Ferrari saying that you would void the warranty if you floored the gas in their cars over a specific number of seconds. Of course, I am not an electronic engineer/designer, who am I to challenge the almighty designers/engineers of state-of-the-art power amps. On the other hand, I would consider preamps with significant DC offset in their output were faulty or extremely poorly designed. They should put a major warning on the output terminals saying that such preamps should not be used with any power amps that could go all the way down to DC. Even if the DC offset does not kill the power amp/speakers, there is a very high chance that the signal in the power amp would clip asymmetrically and led to poor sound at high volume. 最後修改時間: 2010-03-11 20:15:07 |
olddude 正式會員 116.xxx.xxx.127 |
2010-03-11 20:13 |
| [#21] 前石後膽怕燒機嗎 Yes, the tube power amp input crcuit can leak voltage to kill the output stage of the preamp if DC coupled. |
ModernClassic 正式會員 112.xxx.xxx.243 |
2010-03-11 16:15 |
| [#20] 前石後膽怕燒機嗎 The reason for DC output during preamp power up is because the preamp has an output cap. Initially there is no charge in the cap. Upon turn on the tube output DC which then raise the output cap's voltage until it reaches the same DC level. If the amp has high input impedance (i.e., many SS amp) then it takes quite a while to charge up the output cap in the preamp and during this time DC or close to DC signal will appear at the amp's input. Thus this only applies to cap-coupled output preamp. Transformer-output has no such problem as the transformer has limited low freq response. Some tube preamp prevents this by adding a relay to short circuit the output during power up so that the cap can be fully charge quickly. For the same token, tube amp will not be affected as they cannot pass DC in their output (unless it's DC-coupled OTL). |
shostakovich 正式會員 220.xxx.xxx.189 |
2010-03-11 15:02 |
| [#19] 前石後膽怕燒機嗎 0lddule 兄, 你很玄,你常常用問號"?"來結尾,究竟是譏諷?或不懂? 不如請大師您elucidate好嗎? 我一早講明我不是tech guy,我都是聽番來的: 1.胆前阻抗(impedance)如和石後不match,就算無signal/冇開volume,你對低音單元會自動出出入入。 2.支膽在on/off時,會有直流DC,如你件石後是極品----(極品石後通常在放大線路上不用電容,因為電容會過濾signal)-----non-capacitor coupling,就會燒機。 但如你的胆前是有輸出牛(output transformer)設計 eg. Audio Note, Modwright, Ayon........就無問題,可以用乜石都得。 以下是download KRELL 綱頁的warning: http://www.krellonline.com/assets/support/0162_020_MAN.pdf PAGE 13. USING A TUBE PREAMPLIFIER The high DC output of tube preamplifiers may exceed the DC protection circuitry of Full Power Balanced amplifiers. Excessive DC level in a signal can damage amplifiers, speakers, or both. The coupling capacitors in Full Power Balanced amplifiers must be engaged when using a tube preamplifier. An authorized Krell dealer, distributor, or Krell must activate these capacitors. Coupling capacitors must be inserted into the signal path by your authorized Krell dealer, distributor, or Krell before you can use your Full Power Balanced amplifier with a tube preamplifier. IMPORTANT Please read the Warranty, on page 20, to understand the warranty limitations of Full Power Balanced amplifiers when used with Page 20 IMPORTANT The user is responsible for notifying his or her Krell dealer, distributor, or Krell that a tube preamplifier will be used with the Full Power Balanced amplifier, so that the Krell dealer, distributor, or Krell can activate the coupling capacitors. If the user does not notify the Krell dealer, distributor, or Krell and uses a tube preamplifier without the Full Power Balanced amplifier’s coupling capacitor engaged, Krell reserves the right to refuse warranty related service due to DC-related damage. Proof of purchase in the form of a bill of sale or receipted invoice substantiating that the unit is within the warranty period must be presented to obtain warranty 最後修改時間: 2010-03-11 12:46:10 |
cheunggerger 正式會員 121.xxx.xxx.122 |
2010-03-11 12:40 |
| [#18] 前石後膽怕燒機嗎 ＞Non-capacitor coupling hi end power amp, ML, KRELL, ......... WHEN match with tube pre, manufacturers demand their customers to have their amp altered by dealers Oh really!?! Frankly, would you trust someone who claimed that "impedance mismatch between tube preamp and solid state power amp would blew a power amp" to modify your expensive power amp? Not me. Isn't add a coupling capacitor to the power amp kind of defeat the whole purpose of buying a state of the art DC coupled power amp? Also, with the typical lower input impedance of solid state power amp, adding a coupling capacitor would probably reduce the bass in the system. On the other hand, they could be adding a bypass capacitor to cut out the high frequencies. In which case, that would affect the high frequencies. 最後修改時間: 2010-03-11 09:23:15 |
olddude 正式會員 116.xxx.xxx.127 |
2010-03-11 09:07 |
| [#17] 前石後膽怕燒機嗎 For the real HI END solid state power amps, there are no capacitor in input/output stages---as capacitors induce their sonic characters. Non-capacitor coupling hi end power amp, ML, KRELL, ......... WHEN match with tube pre, manufacturers demand their customers to have their amp altered by dealers Excel put a capacitor to both L/R input stage for me. |
cheunggerger 正式會員 203.xxx.xxx.136 |
2010-03-11 01:33 |
| [#16] 前石後膽怕燒機嗎 ＞＞＞有位c-hing教路，膽前石後有兩點要注意。 胆前石後 or 胆前胆後, my experienc is turn on the 胆前 first to avoid the "ba ba" sound. on the other hand, when you turn off, the power amp first. |
aftjv 正式會員 81.xxx.xxx.43 |
2010-03-09 11:45 |
| [#15] 前石後膽怕燒機嗎 ＞其實胆前石後, 石前胆後都冇問題. Exactly. Some people were just making excuses because they didn't know what was the real problem. ＞唔通石前石後, 或者胆前胆後就一世唔會燒機? I have been playing around with electronics and stereo equipment since the early 70's. The only time I blew a power amp was the time I was using a home-built power amp with some sub-substandard parts (poor college student could only afford to buy from supplies stores). I had used a very simple tube preamp driving a solid state amp for a good number of years without problem. Of course, in order to keep the preamp sound good, I kept the preamp powered on all the time and avoided surges at power on as mentioned by some others here. Sometimes, I found it really amusing to see people perpetuating unsustainable myths just because they didn't understand the actual problems they had encountered. I was particularly surprised when a reputable store such as Excel would tell a customer that he blew his power amp (an expensive one too) because of "impedance mismatch" between his tub preamp and the soild state power amp. 最後修改時間: 2010-03-09 09:39:04 |
olddude 正式會員 116.xxx.xxx.127 |
2010-03-09 09:34 |
| [#14] 前石後膽怕燒機嗎 唔通你想佢地會老實話部ML後級自己水皮燒左。 ______________________________________ 講得好! 其實胆前石後, 石前胆後都冇問題. 唔通石前石後, 或者胆前胆後就一世唔會燒機? |
Derek2A3 正式會員 58.xxx.xxx.137 |
2010-03-09 09:20 |
| [#13] 前石後膽怕燒機嗎 ＞olddude, ＞You might be factually incorrect! Please enlighten me on what was happening when the "無signal時 woofers of your speakers would move inward/outward spontaneously" then. I would really like to know how that would be related to the "mismatched impedance" between pre/power amp. Thanks in advance. |
olddude 正式會員 116.xxx.xxx.127 |
2010-03-08 22:58 |
| [#12] 前石後膽怕燒機嗎 olddude, You might be factually incorrect! |
cheunggerger 正式會員 121.xxx.xxx.85 |
2010-03-08 22:38 |
| [#11] 前石後膽怕燒機嗎 ＞假如impedance not match( tube pre/solid state 後),無signal時 woofers of your speakers would move inward/outward spontaneously That would happen if your system is oscillating in a very low frequency. |
olddude 正式會員 116.xxx.xxx.127 |
2010-03-08 22:36 |
| [#10] 前石後膽怕燒機嗎 MICROMEGAMAH, 假如impedance not match( tube pre/solid state 後),無signal時 woofers of your speakers would move inward/outward spontaneously |
cheunggerger 正式會員 121.xxx.xxx.85 |
2010-03-08 22:08 |
| [#9] 前石後膽怕燒機嗎 """"I am surprised that a reputable shop like Excel would tell a customer such BS""" 唔通你想佢地會老實話部ML後級自己水皮燒左。 |
thomasc2 正式會員 61.xxx.xxx.176 |
2010-03-08 21:17 |
| [#8] 前石後膽怕燒機嗎 有位c-hing教路，膽前石後有兩點要注意。 1. 胆前要先開幾分鐘，好讓輸出穩定下來。 2. 不可在中途轉source input，每次開機聽CD就CD，唔好跳去Phono。 各位c-hing有冇意見分享。 最後修改時間: 2010-03-08 20:36:03 |
micromegamah 正式會員 59.xxx.xxx.42 |
2010-03-08 20:32 |
| [#7] 前石後膽怕燒機嗎 ＞Excel warned me with stuff exactly I'd said. I am surprised that a reputable shop like Excel would tell a customer such BS. I wonder would Mark Levinson customer service concur to such statement. |
olddude 正式會員 116.xxx.xxx.127 |
2010-03-08 19:50 |
| [#6] 前石後膽怕燒機嗎 I'm not a tech guy. But I blew my Mark Levinson 333 with a Tube Pre. Excel warned me with stuff exactly I'd said. |
cheunggerger 正式會員 121.xxx.xxx.85 |
2010-03-08 19:43 |
| [#5] 前石後膽怕燒機嗎 ＞膽前石後就會,胆直出DC燒後級! Oh really? Never heard of that. If so, that has to be a serious drift in DC and it would sound very awful before the power amp blew. ＞這是impedence mismatch problem!! Why would impedance mismatch causing DC drift in the pre-amp output? |
olddude 正式會員 116.xxx.xxx.127 |
2010-03-08 19:05 |
| [#4] 前石後膽怕燒機嗎 膽前石後就會,胆直出DC燒後級! 石前永無此問題! 這是impedence mismatch problem!! |
cheunggerger 正式會員 121.xxx.xxx.85 |
2010-03-08 18:45 |
