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- 2003-01-24
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发表于 2011-04-25 12:52
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Audio Research Reference 3
- 测量是在120V交流电压。 测量就左声道和平衡式输入和输出连接，除非另有说明。
- 统一仪器载入增益和均衡I / O是“80”和不平衡的I / O是“93”的前面板显示。
- 此前置放大器不颠倒极性。
- 交流线电流
- 在1kHz输入阻抗：
- = 52K章2000年欧姆非平衡输入
- 平衡输入= 108k欧姆
- 在1kHz输出阻抗：
- 增益，均衡I /最大直径，数量：
- 仪器装载，廖创兴/ Rch的= 3.52X，十点九分贝/ 3.30X，10.4分贝
- IHF型加载，廖创兴/ Rch的= 3.50X，十点九分贝/ 3.27X，十点三分贝
- 增益不平衡的I /最大直径，数量：
- 仪器装载，廖创兴/ Rch的= 1.77X，五点○分贝/ 1.74X，四点八分贝
- IHF型加载，廖创兴/ Rch的= 1.71X，4.7分贝/ 1.68X，4.5分贝
- IHF型灵敏度，标准IHF型输出0.5V的IHF型负载，输入电压：
- 均衡I / O，廖创兴/ Rch的= 143mV / 153mV
- 不平衡的I / O，廖创兴/ Rch的= 292mV / 298mV
- 输出噪声与带宽和音量控制的位置：
- 平衡输出，在最大（103），廖创兴| Rch的，宽带/ A加权=
56.7uV / 9.5uV | 88.8uV / 10.3uV - 平衡输出，在单位增益（80），廖创兴| Rch的，宽带/ A加权=
114.2uV / 11.9uV | 164.3uV / 12.7uV - 平衡输出，在典型的听力水平（低于单位增益（34）为20dB），廖创兴| Rch的，宽带/ A加权=
48.2uV / 8.7uV | 68.7uV / 9.7uV
- 非平衡输出，在最高（103），廖创兴| Rch的，宽带/ A加权=
320uV / 36.0uV | 224uV / 35.7uV - 非平衡输出，在单位增益（93），廖创兴| Rch的，宽带/ A加权=
338uV / 37.4uV | 255uV / 36.2uV - 非平衡输出，在典型的听力水平（低于单位增益（53）二十零分贝），廖创兴| Rch的，宽带/ A加权=
341uV / 36.2uV | 243uV / 34.7uV
一般
音频线的研究参考文献3级前置放大器是该管前置放大器的参考系列的最新版本。 物理上很大，但不是特别大的单位，它的功能对所有的输入和输出平衡和非平衡的连接。 前面板显示屏大，容易阅读从房间 - 一个非常不错的功能。 的音量通过前面板显示屏上已知的参考号码设置现在已经成为现实---远远高于同期基准单位，其中音量设定的猜测和上帝更好。
图1显示了团结的增益为0.5V的仪器和IHF型装载与输入的音量控制频率响应和均衡I / O的这两个通道是在这个内跟踪0.12分贝卷上的控制点。 在此音量设定的带宽（如- 3dB点定义）低于10Hz的少约80kHz的。 注：与IHF型负荷，有一些低频衰减开始显现，由于输出耦合电容，其低频率对负载的IHF型的10k截止频率的大小。
现在，像大多数前置放大器，特别是管设计，高频响应通常是一些音量控制设置功能。 在图表2A和B中的前置放大器的频率响应是指在最高和一个典型的聆听位置两个通道的音量在20dB的增益设置如下所示。 对于这些音量设置，高频率带宽约为200kHz的。 在图表2C型，团结的音量增益四十零分贝以下设置，甚至更广泛的高频带宽呢。 并在最后一卷的位置，前1静音，高频率响应真正开始是在200kHz提高了约5 - 6dB的。 音量控制跟踪是非常多的工作范围内具有良好，普遍优于0.2分贝福利。 我与不平衡的频率响应行为/澳（未显示）本质上是一样的。
图3a显示了总谐波失真和频率与输入电平为赫尔辛基人权联合会和均衡I / O和单位增益仪表负载变动。 该IHF型装载有一点失真，但是，就像装载仪器，变形基本上与频率无关。 图3b和3c说明如何失真水平和不平衡的I / O连接频率而变化。 在这些图表，20Hz和1kHz的本质上是相同的，覆盖，但20kHz的失真是一个多一点。
一个对一个1kHz失真和噪声测试音在0.5V的残余在单位增益输出与仪器载荷谱是在图4A及4B密谋不平衡，均衡I / O的分别。 不平衡的I / O状态似乎有一种低频率的上升相比，均衡I / O的情况。 此外，整体噪音水平处于均衡I / O模式低。 坎为谐波计量的前置放大器级的典型。 占主导地位的是第二谐波信号可以同时为I / O的条件。
- Measurements were made at 120V AC line voltage. Measurements made on the left channel and with balanced input and output connections unless otherwise noted.
- Unity gain for instrument loading and balanced I/O is "80" and for unbalanced I/O is "93" on front-panel display.
- This preamplifier does not invert polarity.
- AC line current draw
- Standby: 0.03A
- Operate: 1.32A
- Input impedance at 1kHz:
- Unbalanced input = 52k ohms
- Balanced input = 108k ohms
- Output impedance at 1kHz:
- Unbalanced output = 320 ohms
- Balanced output = 660 ohms
- Gain, balanced I/O, volume at maximum:
- Instrument loading, Lch/Rch = 3.52X, 10.9dB / 3.30X, 10.4dB
- IHF loading, Lch/Rch = 3.50X, 10.9dB / 3.27X, 10.3dB
- Gain, unbalanced I/O, volume at maximum:
- Instrument loading, Lch/Rch = 1.77X, 5.0dB / 1.74X, 4.8dB
- IHF loading, Lch/Rch = 1.71X, 4.7 dB / 1.68X, 4.5 dB
- IHF Sensitivity, input volts for standard IHF output of 0.5V, IHF loading:
- Balanced I/O, Lch/Rch = 143mV / 153mV
- Unbalanced I/O, Lch/Rch = 292mV / 298mV
- Output noise versus bandwidth and volume-control position:
- Balanced output, at maximum (103), Lch | Rch, wideband/A weighted =
56.7uV / 9.5uV | 88.8uV / 10.3uV - Balanced output, at unity gain (80), Lch | Rch, wideband/A weighted =
114.2uV / 11.9uV | 164.3uV / 12.7uV - Balanced output, at typical listening level (20dB below unity gain (34)), Lch | Rch, wideband/A weighted =
48.2uV / 8.7uV | 68.7uV / 9.7uV
- Unbalanced output, at maximum (103), Lch | Rch, wideband/A weighted =
320uV / 36.0uV | 224uV / 35.7uV - Unbalanced output, at unity gain (93), Lch | Rch, wideband/A weighted =
338uV / 37.4uV | 255uV / 36.2uV - Unbalanced output, at typical listening level (20dB below unity gain (53)), Lch | Rch, wideband/A weighted =
341uV / 36.2uV | 243uV / 34.7uV
General
The Audio Research Reference 3 line-level preamplifier is the newest version of the Reference series of tube preamplifiers. A physically large but not particularly heavy unit, it features balanced and unbalanced connections for all inputs and outputs. The front-panel display is large and easy to read from across the room -- a very nice feature. The setting of volume to known reference numbers via the front-panel display is now a reality --- much nicer than the earlier reference units, where volume setting was by guess and by God.
Chart 1 shows the frequency response with the volume control set for unity gain for 0.5V input with instrument and IHF loading and balanced I/O. The two channels are tracking within 0.12dB at this point on the volume control. The bandwidth at this volume setting (as defined by the -3dB points) is less than 10Hz to about 80kHz. Note: with the IHF loading, there is some low-frequency attenuation starting to show due to the size of the output coupling capacitors and their low-frequency cutoff frequency against the 10k of the IHF load.
Now, as with most preamplifiers, especially tube designs, the high-frequency response is usually some function of the volume-control setting. In Charts 2A and B the frequency response of the preamp is shown for both channels with the volume at maximum and at a typical listening position, set at 20dB below unity gain. For these volume settings, the high-frequency bandwidth is about 200kHz. In Chart 2C, for volume set for 40dB below unity gain, the HF bandwidth is even wider yet. And at the last volume position, 1, before mute, the high-frequency response actually starts to boost being up some 5-6dB at 200kHz. Volume-control tracking is very good over the working range, generally being better than 0.2dB. The frequency-response behavior with unbalanced I/O (not shown) is essentially the same.
Chart 3A shows how total harmonic distortion varies with input level and frequency for both IHF and instrument loading for balanced I/O and unity gain. The IHF loading has a bit more distortion, but, like the instrument loading, the distortion is essentially independent of frequency. Charts 3B and 3C illustrate how distortion varies with level and frequency for unbalanced I/O connections. In these charts, 20Hz and 1kHz are essentially the same and overlaid, but the 20kHz distortion is a bit more.
A spectrum of the distortion and noise residual of a 1kHz test tone at 0.5V output at unity gain with instrument loading is plotted in Chart 4A and 4B for unbalanced and balanced I/O, respectively. The unbalanced I/O condition seems to have a low-frequency rise compared to the balanced I/O case. Furthermore, the overall noise level is lower in the balanced I/O mode. Hum harmonics are typical in level for other preamps measured. The dominant signal harmonic is the second for both I/O conditions.
| Chart 1 - Frequency Response at Unity Gain with IHF and Instrument Loading |
IHF loading
Blue line = left channel
Cyan line = right channel
Instrument loading
Red line = left channel
Magenta line = right channel | Chart 2 - Frequency Response as a Function of Volume Control Setting |
Chart 2A - gain at maximum
Instrument loading
Red line = left channel
Magenta line = right channel Chart 2B - gain at -20dB below unity gain
Instrument loading
Red line = left channel
Magenta line = right channel Chart 2C - gain at -40dB below unity gain
Instrument loading
Red line = left channel
Magenta line = right channel | Chart 3 - Distortion as a Function of Output Voltage and Frequency |
Chart 3A - Balanced I/O
Red line = Instrument loading (20Hz, 1kHz, and 20kHz)
Magenta = IHF loading (20Hz, 1kHz, and 20kHz) Chart 3B - Unbalanced I/O
Instrument loading
Magenta line = 20Hz and 1kHz
Red line = 20kHz Chart 3C - Unbalanced I/O
IHF loading
Magenta line = 20Hz and and 1kHz
Red line = 20kHz | Chart 4 - Distortion and Noise Spectrum |
Chart 4A - Unbalanced I/O
Instrument loading
Red line = spectrum of 1kHz test signal distortion and AC-line harmonics at 0.5V input and output at unity gain. Chart 4B - Balanced I/O
Instrument loading
Red line = spectrum of 1kHz test-signal distortion and AC-line harmonics at 0.5V input and output
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