Boss不做TRUE BYPASS的原因（转）
首先，我们要知道什么是TRUE BYPASS。吉他的信号是高阻抗信号，而效果器处理过的信号阻抗会降低。阻抗的具体概念可以参考度娘百科。
对于TRUE BYPASS效果器，效果器旁通状态下输出的信号与输入信号相同，为高阻信号；而非TRUE BYPASS效果器，在旁通状态下效果器相当于一个放大器，输出了阻抗降低但波形与原来相同的信号。因此，在TB效果器旁通时，几乎与没有串到效果链中相同，不会“吃掉”音色，因此很多追求原味的吉他手喜欢一些经常需要旁通的效果器TB。
但是，TB并不是万能的。因为，当一个效果器频繁在同一个效果链中切换的时候，对于下面的效果器的输入信号的阻抗就会不断地高低变化，应对这种变化，在对整个效果链的调整中就需要费一番心思了。
而Boss之所以不生产TB的效果器，就是为了使效果器旁通与否不影响接下去的效果链输入阻抗。至于TB是否好用，并不是一个客观的概念，因为所谓的“吃”音色，只是一个主观感觉，因为音色确实变得跟不用效果器有区别，不够原味；但是，这种变化并不能单纯地当成是劣化，只是变得不同了而已，只要处理得当，也并非无法调出好的音色。
BOSS的踏板有它的优点，比如直通的切换的时候音色要断一下，BOSS的就不会，这个卖点还出现在随包装附带的广告里面，BOSS单块的说明书上也能看，再说也不是所有人都喜欢直通。boss比较看重完美的切换 。
还有更重要的原因是，BOSS的BUFFERED BYPASS可以避免使用过长连接线（超过5.6米）时的信号损失。在这一点上比TRUE BYPASS来的实用得多。
欢迎大家继续讨论......
[ 本帖最后由 hngz1985 于 2014-2-3 17:05 编辑 ] 我觉得boss dd3是个非常不错的东西，但它会吃音。没有发现它有buffer的功能~
neunaber wet混响同样不是true bypass，但有buffer效果，所以就吃音来说wet比dd3好多了~ 理论上说没有最纯净的音色 因为谁都不知道百分百保真的吉他原声是什么样
“这种变化并不能单纯地当成是劣化，只是变得不同了而已”这句话说得非常好很多人就是一味追求TB 现在我很少研究效果器了 一些东西也不知道是怎么回事了
但是最基本的 买效果器靠自己耳朵 试听什么的都是不准确 甚至是误导的 代理商的话也多半都是夸大 唯一可以信的就是电源规格 其他的都得靠自己去使用
PS BOSS的声音我觉得很差 至少我用过的DS MT这些常见的失真我是这么觉得 为了便宜 仅此 BOSS不由你等屁民去辩解，，纯属一厢情愿。老东西设计缺陷就，怎么用到你来解释呢？熟话说，谎话说三次就变真话，，自己理解成 一套。。最后自己也认为就那么回事。好笑 与成本无关。
我觉得TB和BB各有所长，其实并非TB就多了不起，大多是炒作起来的概念。 关键是动静喜欢不喜欢，其他不考虑。。。 我听说过很多mod作坊给non-tb的做成tb的
但是我没听说tb的要求给做成non-tb的
精打细算的日本人，一个9点开关对他们是很贵的
一颗sd1当推子串进去，后边再串一颗方便做个a/b对比的时候我都受不liao了
non-tb总体不算什么好事情 http://www.petecornish.co.uk/case_against_true_bypass.html
自己去看，解释的清清楚楚为什么不用所谓True Bypass. 63ft会有a hugh loss
那一句话就解决了：一个non-tb串在链条里会让声音变得很糟糕了,多个更是难以想象,这远比这一点loss让人难以承受的多
我自己会花几百人民币买buffer ， 先把9点开关给我装上先，选择权在我
[ 本帖最后由 疯狂的和弦 于 2014-2-5 15:52 编辑 ] "Hey Pete, do you use True Bypass?"
Look out there's a lecture coming:
The "true bypass" function, which is promoted by some, can create dreadful problems with a system that uses many pedals. Take for instance a 15 ft guitar cable linked to ten pedals, each linked by a 2 ft cable, and then onto the amp by a 30 ft cable. If all pedals have "true bypass", and are off, then the total cable length hanging on the guitar output will be 63 ft. This will cause a huge loss of tone and signal level particularly if the guitar is a vintage type with low output and high impedance. The amp volume is then turned up and the treble control increased to compensate for the losses. The inherent background noise now increases by the amount of the gain and treble increase and is usually, in my experience, too bad for serious work. If one of the pedals is now switched on, then it's (hopefully) high input impedance (and usually low output impedance) will buffer all the output cables from the guitar and the signal level will rise due to the removal of some of the load on the pickups (i.e.: 17 ft instead of 63 ft of cable). The treble will rise and the tone and volume will not be as before. If that pedal was say a chorus or delay, devices which are usually unity gain, then your overall signal level and tone will vary each time an effect is added...not a very good idea.
Some pedals have an input impedance which is far from high in real terms; the input impedance of the vast majority of amps is 1 Megohm (one million ohms) and in my experience there are few effects pedals that have the same input impedance. A load on the guitar of less than 1 Megohm will reduce the volume and high frequency content of the pickup signal thus giving rise to complaints that "this pedal looses tone/volume" etc. Many effects I have tested have an input impedance of less than 100 Kilohms (ie: only one tenth of the amp input impedance) and cause serious signal losses in the effects chain.
My system, which I devised in the early 70's, is to feed the guitar into a fixed high impedance load, which is identical to the amp input, and then distribute the signal to the various effects and amps by low impedance buffered feeds. This gives a constant signal level and tonal characteristics, which do not change at all when effects are added. The proof that this works are in the recordings of our clients: Roxy Music; The Police; Queen; Pink Floyd; Bryan Adams; Lou Reed; Dire Straits; Paul McCartney; Sting; Jimmy Page; Judas Priest; Black Sabbath....
So the answer to your question re "true bypass" is no, I do not use this system in my EffectsBoards/Racks as it can seriously degrade your sound. All my current effects pedals (excluding Vintage Series) which are derivedfrom our large systems have, as the main input stage, a fiendishly clever pre amp that has the same characteristics as the input of a tube amp (1 Megohm/20pF), a highly efficient filter to eliminate the possibility of radio breakthrough and a low output impedance so that any following pedals/ cables etc. will not impose a load on the guitar signal. This pre amp is fitted to all our large stage systems and has always met with huge approval; not only from the guitarist but also the PA operator who is so happy to have constant level and tone presented to his mixing board. I go further with large systems and provide several inputs, each with the isolating pre amp and a gain compensation pre amp so that many different guitars can be level matched into the system. In addition a 20 segment PPM type display provides visual indication of signal level in our Effects Boards and Rack Systems.
©Pete Cornish 2003
回复 3楼 Tim5 的帖子
BOSS的块很不错回复 12楼 末日英雄 的帖子
没觉得哪儿好 The "true bypass" function, which is promoted by some. BOSS 吃音色不在于它采用什么开关模式，而在于整体线路的设计，另外Buffer也是有好坏的，就好像都是Boost，差异也很大 英文看不懂，看懂的能翻一下？ BOSS也就卖那个价，可以的了
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