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发表于 2010-11-24 19:46
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可否把翻译的相关资料发上来，让大家分享一下。
wb136 发表于 2010-11-21 20:01 
实在抱歉！原来的翻译软件找不到了。在线翻译的一些软件翻译不完整。
我把原文发上来，要看的兄弟翻译一下吧
以下是原文（英语）
Additional comments:
Most of the guidelines listed on the detailed KSA50 wiki apply to the KSA100 too. The original VN021/VP021 MOSFETs arent available anymore. Provision has been
made for four different packages of suitable replacements as listed. TO-92 is the most
popular case type, but the HD-1 package has the advantage of being compatible with
DIP-4 sockets and thus easy to remove/replace. The SOT-223 package is SMD and not
hard to solder, but once its tab has been soldered it will be difficult to remove without
damaging either it or the board. It has the best heatsinking ability though due to the large
amount of plated vias placed underneath its PCB pads. Its recommended to initially just
solder the three pins and leave the tab for when everythings working. Although its
connected to the drain, electrical contact isnt required for proper operation. ZD1&ZD2 should ideally be matched, since zeners have large tolerances. Match at the
operating current level. Q1-Q4 should ideally be matched, and at the correct bias current. The 2SA/2SC types
specified are the same as in the original, but the BC ones will do just as well or perhaps
even better. When using fast output transistors, slow types such as MPS/MPSA should
be avoided. Q1-Q4 should be mounted back-to-back and preferably coupled with a layer of thermal
grease and kept together with a piece of heatshrink as shroud. This will improve thermal
tracking. The transistor types used for Q13-Q17 will affect the bias and thus value of VR2, and
should be kept in mind if experimenting with different gain types. Q13-Q17 should be mounted on the same heatsink, on the area provided. Care must be
taken that their collectors arent shorted out with proper isolation. The collective idle
power dissipation is around 12W. Of the cascade transistors, only Q9&Q10 may benefit from a small heatsink. Its
Q11&Q11 partners dissipate significantly less power. The original output transistors used were MJ15003/15004. The newer MJ21194/21193s
are a drop-in replacement. More modern plastic transistors e.g. MJL32821/1302 are
faster, but requires more attention to wiring. Long wires running to the transistors can
lead to instability. Matching the output transistors at the intended bias level can prove beneficial but is
generally not required. Matching D5 and D6 will not do any harm either. Power can be applied to either the pads provided at the top such as on the original, or at
the 3-pin connector J1 at the bottom.
J4&J5 connect the front-end power to the drivers and should be used or hardwired when
a single power supply is used to power everything. If the CPx capacitors are installed,
J4&J5 can be replaced with 0.5W resistors between 0R and 47R, with power applied to
the driver side. This will form an RC filter to improve the front-ends power quality.
Increased resistance will improve filtering, but increase the front-end voltage drop. If separate power supplies are used, J4&J5 should be open-circuit, with the front-end
powered at J1 and the drivers by the open pad at the top. J3 can be used to short out C4 and thus remove it and the 1000uF electrolytics from the
signal path. This should be done with care as it will turn the amp into a fully DC-coupled
design, especially if the preamp is DC-coupled too. A sensitive and fast-acting DC-
sensing circuit or DC servo may be necessary and is highly recommended. Experiment
with this jumper with caution. Refer to the KSA50 wiki for proper grounding principles. C8, C9 and all the CPx caps were absent on the original. Since theyre fairly cheap they
are recommended though. Not all are needed; provision was merely made for flexibility. Note that the CPx decoupling capacitors, particularly the large-value elctrolytics, are likely
to introduce turn-on thump on the speakers. Although this is generally harmless, a delay
or DC sensing circuit on the speaker outputs may be beneficial. If no CPx capacitors are
used, there should be no/little turn-on thump due to the resistive current sources. If a regulated supply is used for the front-end and-or drivers, the power-on sequence is
important. The sequence should be output, driver, front-end, or thump is surely to result.
Longer time constants may do the trick, but properly delayed sequencing is
recommended. This method will reduce/eliminate turn-on thump AND be friendlier to the
amp itself compared to the DC sensing circuit, but the latter will provide steady-state
protection as well. With ingenuity, these circuits can be combined and minimized. The power diodes between output and the respective power rails are not necessary for
operation and may be omitted in most cases. They provide limited protection for when the
rails drop below the output amplitude. On the Mk1, there was no protection circuitry. Soft-start was merely a thermister in series
with the incoming AC Live. This provided limited inrush protection, especially if powered
up when still warm, and dissipated some power itself. The Mk2 had a DC sensing circuit
with a relay in series with the speaker outputs, as well as a resistor in series with the AC
Live that is shorted out with a power relay a brief moment after powerup. The original bias to provide 100W class-A into 8ohms is 5A; or 620mA per transistor if 4
pairs are used. Many people have reported that dropping the bias to 580mA or even
much lower has no effect on the sound, and reduces power dissipation and heatsink
size/fan speed. The speaker impedance will influence the optimal bias level, but generally
speaking a speaker of 4ohms nominal or higher with little deviation and phase shift will be
happy with <100W reduced bias. Reduced bias can even improve quality as it reduces
strain on the transformers and supply capacitors, and subsequently reduce ripple in
particular on smaller supplies. If forced-cooling are used, AC fans are highly recommended. Even with separate
supplies and regulation, DC fans are likely to inject motor noise. PWM DC control over
fan speed is even worse. Krell used Dale resistors throughout; 0.5W for all the ones depicted here, 5W for the
emitter resistors, snubber and earth/ground separation. The earth/ground separation was merely a 10R resistor running from each channels
ground connection at the PSU caps bus bar to the chassis, which was in turn connected
to earth (safety) ground. The snubber (zobel) RC filter on the output should be placed as close to the output as
possible, preferably on the speaker terminals itself. The values used on the original were
100nF and 5R6. A film cap with 100V+ rating should be used along with a non-inductive
resistor. C1 was an ERO MKP. It should be noted that Krell used ERO MKPs throughout almost
all their products including the very recent designs. Rather mid-level cap. C4 & C7 were axial Roederstein film types. C5, C6 and Cx were silvered mica types. Cx has no provision on the board, but is recommended. It wasnt included on the
schematic itself, but is present on the actual Mk2 boards. It will improve stability for
driving reactive loads. The electrolytics pad sizes provided for were based on those from the Panasonic FC
series, but most other brands of the same value will have compatible packages. C2 & C3 were Roederstein electrolytics in a plastic case. A single 470uF bipolar cap e.g.
Black Gate N or NX can be used instead, but the value can be higher (but not much
lower or bass response may suffer). Although boutique caps arent a necessity, a proper
low-ESL electrolytic of at least a reputable brand name is recommended. Panasonic FC
and Elna Cerafine are good choices and not very expensive. Low-ESR isnt necessary,
but since these are often higher overall quality may offer good performance. C4 should be a quality cap with good high-frequency response. MKP box-types are
recommended MKT will also work but is not as good. Avoid ceramics, unless absolutely
necessary and of a quality series such as NPO or COG. For C7 the quality need not be as high. VR1 and VR2 should ideally be a 10-turn type. 25-turn is overkill and just an annoyance
when making large adjustments. |
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96471| 384
发表于 2010-11-20 22:29
还有角铝太宽了导热距离长，我的功率管都是平行角铝而不是垂直角铝的，一般温差10度左右吧