토이 팹 : : ' jlh ' 태그 의 글 목록 
 ' jlh ' 에 해당 되 는 글 3 건 
 2010 . 06 . 22 1969 년 식 JLH 의 온전 한 구현 
 2010 . 06 . 22 여러 가지 의 JLH 버전 들 ( 2 ) 
 2010 . 06 . 22 02 : 32 
 오디오 DIY 맨 으로 JLH 를 몇 개 만들 었 지만 아주 온전 하 다고 는 볼 수 없 었 는데 
 출력 석 을 내 마음 대로 썼 기 때문 이 다 . 
 얼마 전 김형섭 님 이 완전 한 JLH 의 워킹 카피 를 만드셨 는데 전 원부 까지 완전 복원 된 셈 이 다 . 
 방열기 가 작 지만 케이스 에 넣 을 때 큰 것 으로 넣 으면 되 니 별 문제 는 없 다 . 
 아주 좋 은 소리 를 내 는 DIY 오디오 의 중요 한 앰프 하나 가 완전 복원 된 셈 이 다 . 
 케이스 에 들어가 면 아주 좋 을 것 같 다는 생각 이 든다 . 
 긴 세월 동안 들 을 수 있 는 얼마 안 되 는 앰프 중 에 하 나다 , 거하 지 도 않 으며 10 와트 정도 의 출력 으로 
 잘 조정 되 면 소리 는 정말 최고 다 . 클래스 A 의 성배 같 은 앰프 중 하나 다 , 
 나머지 는 알레프 와 F 5 , hiraga 같 은 앰프 다 . 물론 크 렐 ksa - 50 이나 다른 상업 용 앰프 들 도 중요 하 다 . 
 그러나 10 와트 언더 에서 는 오리지널 과 양 전원 버전 은 정말 최고 다 . 
 많 은 앰프 를 들 어 보 았 어도 변함 은 없 다 . 
 회로 는 오리지널 그대로 . . 
 많 은 사람 들 이 만들 어 보 았 으면 하 는 앰프 이 기 도 하 다 . 
 벤치마크 앰프 로 수많 은 영감 을 낳 게 한 회로 로 40 년 이상 사람 들 의 사랑 을 받 고 있 다 . 
 어느 정도 많 은 사람 들 이 만들 어 보 면 음질 과 회로 에 대해 토론 이 될 것 같 기 도 하 다 . 
 1969 , jlh , 오디오 
 2010 . 06 . 22 02 : 31 
 이상 하 게 도 이 글 은 비 공개 로 되 어 있 었 다 . 
 별 내용 은 아니 지만 무언가 더 끄적거리 고 공개 로 바꿀 예정 이 었 던 것 같 다 . 
 1 . DOZ 를 제외 한 버전 으로 제작 에 참고 한 것 은 Nob 라는 일본 사람 의 글 이 다 . 
 半 導 体 アンプ の 7 台 目 です 。 
 JLH Class - A Amp を 作成 してみました 。 
 今回 はこの 2003 年 版 を 基 に 作成 しました 。 
 回路 はこのようになりました 。 
 出力 段 には 2 SC 5200 を 採用 しました 。( 千石 で 300 円 と 安 かったので ) 
 ドライバ ( と 言 えるか ) には 2 SC 3421 。( これも 千石 で 50 円 と 安 かったので ) 
 定 電流 回路 には 2 SA 1538 を 。( 2 SC 3421 の ペア でこれも 50 円 ) 
 初段 およびその 他 の 定 電流 回路 には 2 SA 1015 。( 秋 月 で 1000 円 / 200 個 ) 
 抵抗 は 0 . 33 Ω 5 W 以外 、 在庫 があるものは 金 属 皮膜 、 なければ カーボン です 。 
 コンデンサ ですが 、 電解 はふつ ー のもの 。 カップリング の C 1 は 結局 外 しました 。 
 試作 したところ 、 やはり A 級 です 。 発 熱 が 半 端 ではありません 。 
 半 固定 抵抗 の VR 1 , 2 , 3 は 中 点 にしておきます 。 
 この 場 合 0 . 33 Ω の 両 端 の 電 圧 は 0 . 15 V 程度 です 。 
 これはもう 、 作 ってみるしかないです 。 
 特 に ウッドベース の 音 にはしびれます 。 
 2 N 3055 version 
 その 後 、 秋 月 で １ つ １５０ 円 で 売 っていた 2 N 3055 を 使 って 、 もう １ セット 作 ってみました 。 
 2 . 그런데 이 앰프 는 본질 적 으로 2003 업데이트 의 일본 판 이 다 , 
 3 . http : / / www . tinholt . eu / jlhevolution . htm 이것 은 아직 분석 을 안 했 다 . 
 4 . 그런데 정말 재미있 는 분석 은 정작 pass 가 만든 부분 이 다 . ( 내용 은 첨부 화 일 참조 ) 
 The PLH Amplifier By Nelson Pass 
 In 1969 John Linsley 쵩 ood wrote in Wireless World : 
 During the past few years a number of excellent designs have been published for 
 domestic audio amplifiers . However , some of these designs are now rendered 
 obsolescent by changes in the availability of components , and others are intended to 
 provide levels of power output which are in excess of the requirements of a normal living 
 room . Also , most designs have tended to be rather complex . 
 In the circumstances it seemed worth while to consider just how simple a design could be 
 made which would give adequate output power together with a standard of performance 
 which was beyond reproach , and this study has resulted in the present design . 
 He then described a Class A power amplifier using three gain stages of Bipolar transistors in a 
 topology which continues to be admired for its elegant simplicity and sound quality . 
 The centerpiece of this design is the middle stage , an NPN transistor used as a phase splitter , 
 simultaneously driving the positive half of the output stage and the negative half with symmetric 
 signals of opposite phase . 
 Figure 1 shows a simplified version of the JLH topology . Signal input appears at the Base of 
 Q 1 , and is amplified and inverted to drive the Base of Q 2 . Q 2 acts as a gain device and also a 
 signal splitter , driving both Q 3 and Q 4 simultaneously , but out of phase with each other . Q 3 and 
 Q 4 form the output transistors , Q 3 operating as a Common Emitter gain device , contributing 
 current and voltage gain , and Q 4 operating as a Common Collector device contributing only 
 current gain . The resistors provide bias for the system , and R 1 and R 2 feed the output of the 
 amplifier in a loop back to the emitter of Q 1 . 
 Q 2 is the heart of the design , and in my opinion , it is the elegant economy with which it performs 
 the complementary gain to drive the output devices that gives the circuit its classic beauty . 
 The JLH was designed at a time when `` the tube era was in decline '' and the new generation of 
 designers were pulling out all the stops to create big science amplifiers ? pure voltage sources 
 with high power and infinitesimal distortion -- complex circuits with lots of feedback . 
 36 years and a little progress later , we can perhaps appreciate the simple charm of the JLH 
 topology as an exercise in minimalism , but if you haven ' t listened to one , you might be very 
 surprised by the quality of sound , which is extraordinarily good within it ' s power limitations . If 
 you have efficient speakers and you like to listen to two 춃 hannel sound at reasonable levels , the 
 JLH is still in the top rank . 
 chip , but it produces real music . Its flaws are not irritating and it does a wonderful job wringing 
 more music out of modern recordings and even MP 3 ' s . I can ' t think of another transistor design 
 from that era that works as well . 
 Figure 2 shows the circuit rendered more completely , but for more extensive documentation on 
 the versions of the JLH amplifier , I recommend The Class A Amplifier Site : 
 In Figure 2 additional details of setting up the DC bias for each device are shown , where 
 capacitors are used to separate DC values from AC values . C 1 separates feedback from bias 
 current . C 2 separates input signal from input DC bias voltage and C 3 blocks the output DC of 
 the amplifier from the load . C 4 removes supply noise from the voltage powering the front end of 
 the amplifier , and C 5 forms a `` bootstrap '' circuit , making resistors R 5 and R 6 behave more like a 
 constant current source at audio frequencies . 
 The original JLH amplifier has approximately 55 dB of open loop gain divided into 22 dB of 
 amplifier gain and about 33 dB of feedback . As detailed in the original article , it delivered 10 
 watts at approximately . 1 % harmonic distortion or less . 
 The amplifier ' s popular longevity speaks volumes about the quality of its sound , and this is 
 understandable given its simplicity coupled with excellent measured performance . It has a 
 particularly tube 춍 ike quality compared to the more complex solid 춖 tate designs of the era and 
 The distortion is largely 2 nd harmonic , and is closely proportional to the output voltage . This 
 means that . 01 % distortion at . 1 watts becomes 1 % at 10 watts , and you can draw a pretty 
 straight line between the two points on a logarithmic graph . Such a curve is characteristic of a 
 single 춅 nded output topology , and there have been arguments regarding whether or not the 
 output stage is single 춅 nded Class A , push 춑 ull Class A or a mixture of both . We will be having 
 some fun with that later . 
 One flaw in the original JLH design was that its bias current , that idling current which flows 
 through the parts of the circuit , had some dependency on the power supply voltage , resulting in 
 altered performance for different AC line voltages . Power supply regulation solves this problem 
 neatly , but there were other ways this was addressed in later versions of the circuit . 
 John Linsley 쵩 ood published an update to the amplifier in 1996 that addressed bias stability 
 issues , parts substitutions , and provided a version that had a direct 춃 oupled output , eliminating 
 the output capacitor . At the same time , it was in many ways the same amplifier , the measured 
 performance being very similar . 
 The JLH circuit continues to be interesting to the audiophile community and has been the 
 subject of several updates . Figures 3 and 4 show simplified schematics of later generations of 
 JLH amplifiers . 
 Figure 3 shows a simplified schematic of the 1996 version published by John Linsley 쵩 ood that 
 fixes the bias stability issue with the addition of Z 1 and the Q 5 portion of the circuit . This version 
 also direct coupled the output of the amplifier , using dual supply rails . 
 In 2000 someone else produced the circuit seen in Figure 4 , where constant current sources are 
 used to bias the first two gain stages , giving good power supply rejection to the circuit . This 
 version also doubled up on the number of output devices . You will notice that Fig 1 -- 4 have 
 their feedback loop addressing the Emitter of the feedback transistor . Nowadays they have 
 gotten fancy and call it `` current feedback ''. 
 Just for your entertainment , I cobbled together the circuit of Figure 5 shows an example with a 
 differential input . An obvious variation , but I haven ' t seen it used . You can drive this input stage 
 with a balanced signal by lifting C 1 from ground and driving it as a negative input . At 100 ohms 
 each , R 6 and R 7 will give this input about the same open loop gain as the original input 
 transistor with the 220 ohms degeneration of the original feedback impedance . 
 I recently measured the performance of a working copy of the circuit of Figure 4 . It had 17 . 5 volt 
 supply rails and was biased at about 2 amps per channel . The open loop gain is also about 55 
 dB into 8 ohms , and its measured performance is comparable to the original circuit . 
 Figure 6 shows the distortion versus output power . The bandwidth of the amplifier is -- 3 dB at 
 100 KHz , the damping factor is about 35 , and the distortion versus frequency is fairly flat , rising 
 slightly at 20 KHz . 
 One of the issues that arise from adding gain stages to amplifiers is that while they increase the 
 open loop gain and allow more feedback correction , they themselves are the source of 
 additional distortion . While the extra feedback can lower the distortion numbers , usually the 
 additional circuitry is reflected in a more complex distortion character having higher order 
 harmonics and inter 춎 odulation components . These are generally agreed to be less musical 
 Michael Cunningham wrote , `` Novelists must usually decide what degree of slavish accuracy 
 would make their stories more alive , and what degree would make them less . '' The amplifier 
 designer has a similar problem to solve . It ' s not hard to make an amplifier that measures well -- 
 it ' s comparatively hard to please audiophiles . 
 My own approach is to make the signal path as simple as possible , work to lower the distortion 
 in agreement with the comments in Linsley 쵩 ood ' s original article . The result is not always the 
 best objective measurements , but the sound is often interesting . 
 The 3 춖 tage topology of the JLH amplifier routinely uses simple Class A operation and about 33 
 DB negative feedback to achieve this performance , and this lured me to consider what kind of 
 amplifier I could achieve with an even simpler circuit and less feedback . The output stage and 
 the intermediate phase splitter cannot be dispensed with and still resemble a JLH , but you can 
 certainly remove the input transistor . 
 4 . diyaudio 에 나오 는 쓰레드 2003 년 의 글 에 는 여러 가지 대화 가 나오 고 170 여 페이지 뷰 를 넘어간다 . 
 그 중 의 하나 는 없 어 진 웹 사이트 에 있 던 내용 이 다 . 
 . step param A LIST . 17 . 35 . 7 1 . 4 
 AMP , jlh , 오디오 
 Total 524 , 358