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How We Test Preamplifiers 如何测量前级 [复制链接]

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leslie

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发表于 2011-04-25 12:50 |显示全部
Our preamplifier measurements are performed in the laboratory of Bascom H. King (BHK Labs), audio-engineering consultant and equipment reviewer. The various tests are done with an Audio Precision System Two Cascade, the premier piece of audio-measurement equipment. All measurements are performed separately from the subjective evaluation -- the body of the review.
A word about the IHF testing conditions:
The Institute of High Fidelity (IHF) came up with a set of standards for measuring audio equipment in 1978, later updated by the Electronic Industries Association (EIA) in 1981.
Bascom King has chosen to use a number of the IHF conditions for testing preamplifiers based on his experience testing many preamplifiers for the now-defunct Audiomagazine.

Additional Data Section

This section contains some ancillary measurements in tabular form. Measurements here include preamplifier gain and sensitivity, output noise, AC-line power draw at idle, input/output polarity, and input and output impedance at 1kHz.

Measurement Summary

The main purpose of this section is to give pertinent details that correspond directly with the charts and help readers interpret the visual data. Salient points about the chart results and additional measurements are included, along with other pertinent comments on the preamplifier’s behavior.

Chart 1 - Frequency Response at Unity Gain with IHF and Instrument Loading

  • Purpose: Gives an indication of how flat and uniform the frequency response of the preamplifier is and how this response varies with output loading.
    This test is done by setting the volume control for unity gain with IHF loading.
    A standard IHF input signal level of 0.5V is applied.
    What it tells you:
    The comparative response with IHF loading (10k ohms in parallel with 1000pF) and with the instrument loading (100k ohm in parallel with 300pF) gives an idea what to expect with different power-amplifier input impedances and interconnect capacitance.
    Some preamplifiers have relatively small film output coupling capacitors and if connected to a power amplifier with low input impedance, some loss of low-frequency response will occur.
    If a long run of high-capacitance interconnect from preamplifier output to power amplifier input is used, the high-frequency response with the
    IHF
    load will be relevant.

Chart 2A-D Frequency Response as Function of Volume-Control Setting

  • Purpose: Shows how the frequency response and channel balance vary with volume-control setting.
    Volume control is set to maximum and a reference level is established as 0dB.
    Output loading is IHF.
    Measuring the left channel, the volume is reduced to -6dB, to 15dB below unity gain, and then to the -70dB level.
What it tells you: With most designs, the high-frequency response will change with volume setting because the source resistance that the power amplifier sees is a function of the volume-control setting.
The highest resistance occurs at -6dB of attenuation, and, in most cases, this will cause the high-frequency response of the preamplifier to be less than with the volume at maximum or down at lower working attenuations of perhaps 15dB below unity gain, where most use occurs.
In many instances, the preamplifier can’t sustain linear output at high frequencies at the elevated output level with the volume control near full up with the standard input level of 0.5V.
In such cases, the high-frequency response will appear to roll off much sooner than at lower levels due to the phenomena of slewing, where the output waveform looks more like a triangle shape than the proper shape of a sinewave. For the reference input level of 0.5V, there may be output clipping or high-frequency slewing at the maximum clockwise level in some cases if the unit under test can't put out 5V with the usual preamp line level gain of 20dB (10x).

Chart 3 - Distortion as a Function of Output Voltage and Frequency

  • Purpose: Illustrates how preamplifier distortion varies with output voltage, frequency, and output loading.
    Measurements are made at frequencies of 20Hz, 1kHz and 20kHz as a function of preamplifier output voltage at unity gain and with IHF and instrument loading.
What it tells you:
With most solid-state designs, there is not much difference with IHF or instrument loading.
With most tube designs, there may be considerable difference in distortion versus output loading.

Chart 4 - Distortion and Noise Spectrum

  • Purpose: Shows a plot of the distortion and noise of a 1kHz test signal at an output voltage of 0.5V for 0.5V input and IHF loading.
What it tells you: At standard output of 0.5V and IHF loading, this plot shows how much hum and noise are present along with the distortion spectra of the 1kHz test signal.

Chart 5 - Tone-Control Characteristics (if tone controls present)

  • Purpose: To plot the tone-control characteristics.
What it tells you: The shape and range of boost and cut of the tone controls.

Chart 6 - Phono-Stage RIAA Equalization Error (if phono stage present)

  • Purpose: To plot the accuracy of the phono stage's’s RIAA equalization.
What it tells you:
How well the circuit design properly implements the RIAA equalization function.

Chart 6 - Phono-Stage Distortion vs. Frequency and Output (if phono stage present)

  • Purpose: Illustrates how the phono-circuit distortion varies with output voltage, frequency, and output loading.
    Measurements are made on a pre-equalized basis at frequencies of 20Hz, 1kHz and 20kHz as a function of preamplifier output voltage
    and with IHF and instrument loading at the tape output.
What it tells you: With most solid-state designs, there is not much difference with IHF or instrument loading.
With most tube designs, there may be considerable difference in distortion and low-frequency response with output loading.
In the case of these measurements at tape output, the loading effect would be relevant to the input characteristics of whatever recording device or other device connected to the tape output connectors.
我们的前置放大器测量是在巴斯科姆阁下国王（的BHK实验室），音频设备，工程顾问及评审的实验室。 各种测试已经完成了一个音频精密系统的两个梯级，音频测量设备总理一块。 所有的测量是分别从主观评价 - 该审查机构。
一个条件字有关IHF型测试：
该研究所 高保真（台湾）来注册（环评1981）与一组标准衡量音响电子设备于1978年，后来更新的行业协会。
巴斯科姆国王选择使用一些条件的IHF型为解散的正在测试基于前置放大器前置放大器的测试经验对他的许多 音乐杂志。

第附加数据

本节包含一些辅助以表格的形式测量。 这里包括前置放大器增益的测量和灵敏度，输出噪音闲置，输入/输出极性，以及输入和输出阻抗，在1kHz交流线路功率消耗。

观测综述

本节的主要目的是让有关的细节，直接对应的图表，帮助读者理解的可视化数据。 有关图表和额外测量结果的要点包括，以及对前置放大器的行为的其他有关评论。

图1 - F 在单位增益requency响应与IHF型和仪器载入

  • 目的： 给出了一个加载的一个指标，如何平整，均匀的频率响应前置放大器以及如何输出响应随。
    这项测试是通过设置加载与IHF型音量增益控制团结。
    一个标准IHF型输入信号电平为0.5 V的。
    它告诉你：
    比较）为响应IHF型负载（用10k欧姆并联在为1000pF），并与仪器加载（与100K的并行欧姆300pF一个想法所期待的不同功率，放大器的输入阻抗和互连电容。
    一些前置放大器具有相对小电影输出耦合电容，如果连接到功放的输入阻抗低，一些反应消失的低频率会发生。
    如果电容长期来看，高互连前置放大器输出到功放的输入使用时，高频率响应
    IHF型
    负荷将是相关的。

图2A的三维 控制体积响应频率为功能设置

  • 目的： 如何通道的频率响应和平衡各不相同。与音量控制设置显示
    控件设置为最大，建立一个参考水平。为0dB的音量
    加载IHF型。输出
    测量左声道，体积减小到- 6dB的，获得低于15dB的团结，然后到- 70dB的水平。
它告诉你： 在大多数设计中，高频响应会随设置音量，因为源抵抗，功率放大器看到的是一个设置功能的音量控制。
抗性最高发生在- 6dB的衰减的，而且，在大多数情况下，这将导致反应的前置放大器的高频率低于其最大音量或。下跌发生在较低的工作也许15dB的衰减使用下面单位增益，大多数
在许多情况下，前置放大器可以'吨维持0.5V的标准输入电平与线性输出接近全在高频率在提升的输出音量控制水平。
在这种情况下，高频响应会出现下线在较低水平相比，由于更快正弦波现象回转，其输出波形的形状看起来更象一个较合适的三角形。 对于0.5V的参考输入的水平，有可能会输出限幅或在某些情况下的水平高频率的最大顺时针回转时如果测试单位根据难救）提供5V通常的前置放大器（增益为10倍，线路电平为20dB。

图3 - 频率失真，和一个函数的输出电压

  • 目的： 说明如何前置放大器的失真随输出电压，频率和输出负载。
    测量是提出和加载频率为20Hz，1kHz的20kHz的功能作为乐器前置放大器的输出电压增益，并与国际赫尔辛基人权联合会和。
它告诉你：
由于大多数的固态设计，没有太大的区别与仪器载入IHF型或。
对于大多数管设计，可能有很大的差异，输出负载与变形。

图4 - 失真和噪声频谱

  • 目的： 显示装载情节的失真和噪声测试信号的一个1kHz IHF型0.5V的输入和输出电压为0.5V的。
它告诉你： 在国际赫尔辛基人权联合会载入标准输出0.5V和，此图显示了嗡嗡声和噪声是目前随着1kHz的测试信号的失真谱图。

图5 - 音频控制特性（如音调控制存在）

  • 目的： 要绘制的音频控制特性。
它告诉你： 增强的形状和范围，降低了音调控制。

图6 - 唱机级RIAA的均衡误差（如唱机阶段存在）

  • 目的： 要绘制的均衡精度唱机stage's的美国唱片工业协会。
它告诉你：
如何正确的电路设计和实现了RIAA的均衡功能。

图6 - 唱机级失真与频率和输出（如唱机阶段存在）

  • 目的： 说明了唱机电路失真随输出电压，频率和输出负载。
    测量是为20Hz，1kHz的频率和20kHz上预先在均衡的基础上作为前置放大器输出电压的作用
    ，并与国际赫尔辛基人权联合会和仪器载荷在磁带输出。
它告诉你： 由于大多数的固态设计，没有太大的区别与仪器载入IHF型或。
对于大多数管设计，可能有很大的差异，输出负载频率响应和低失真。
在这些测量案件在磁带输出，负载效应将是有关到磁带输出连接器的输入特性的任何录音设备或其他设备连接到。
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leslie

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发表于 2011-04-25 12:52 |显示全部

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
      • 待机时：0.03A
      • 操作：1.32A
    • 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：
      • = 320欧姆非平衡输出
      • 平衡式输出= 660欧姆
    • 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

    测量综述

    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

Measurements Summary

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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发表于 2011-04-25 12:53 |显示全部

Bryston BP 6 C-Series Preamplifier

Additional Data


    • 测量是在120V交流线路电压和左声道，除非另有说明。
    • 此前置放大器不颠倒极性。
    • 交流线路电流：0.12A。
    • 在1kHz输入阻抗：47.0k欧姆。
    • 在1kHz输出阻抗：75欧姆。
    • 增益最大音量：
      • 仪器装载，廖创兴/ Rch的= 3.366X，一十点五分贝/ 3.371X，十点六分贝
      • IHF型加载，廖创兴/ Rch的= 3.341X，10.5分贝/ 3.346，一十点六分贝
    • IHF型灵敏度，标准IHF型输出0.5V的IHF型负载，输入电压：
      • 廖创兴/ Rch的= 149.7mV / 149.4mV
    • 输出噪声与带宽和音量控制的位置，宽带/年μV的，1kHz的输入终端，LCH的加权| Rch的：
      • 在最高：132.1μV/7.5μV|132.8μV/8.3μV
      • 统一增益：132.8μV/8.4μV|138.5μV/8.4μV
      • 最低：133.1μV/9.0μV|133.5μV/9.0μV

    测量综述

    一般
    英国石油公司6的Bryston C系列线路级前置放大器，所以许多单位一样这些天，是一个简单，用最小的额外功能的基本设计。
    关于本单位的测量注：两个通道测量非常接近对方与该音量控制跟踪，异常的，而在其他一些测试，前置放大器，更好地仍然在各方面完全可以接受。
    图1显示了团结的装载与仪器0.5V的输入增益设置音量控制频率响应。 在此图表，显示两个通道。 作者：IHF型负载效应基本上是可以忽略不计。 这两个通道是在0.4dB的跟踪在此卷上的控制点。 该单位的带宽（如- 3dB点定义）低于10Hz的少约90kHz。 此外，由于频率响应没有改变设定为最大低至- 70dB的衰减量明显，没有图2显示这些变化。 音量控制，通道间是在大约0.7分贝跟踪低至- 70dB的衰减。
    图3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团结的增益设置音量控制仪表负载变动。 在这个设计中，没有使用仪器或者IHF型负载，电路性能最好的属性差异。
    一个对一个1kHz测试音失真和噪声与IHF型装载0.5V输出频谱中残留绘制图4。 交行的嗡嗡声谐波这里相对较低。 在这一产出水平，信号谐波得过低，不可见。
  • Measurements were made at 120V AC line voltage and on the left channel unless otherwise noted.
  • This preamplifier does not invert polarity.
  • AC line current draw: 0.12A.
  • Input impedance at 1kHz: 47.0k ohms.
  • Output impedance at 1kHz: 75 ohms.
  • Gain, volume at maximum:
    • Instrument loading, Lch/Rch = 3.366X, 10.5dB / 3.371X, 10.6dB
    • IHF loading, Lch/Rch = 3.341X, 10.5dB / 3.346, 10.6dB
  • IHF Sensitivity, input volts for standard IHF output of 0.5V, IHF loading:
    • Lch/Rch = 149.7mV / 149.4mV
  • Output noise versus bandwidth and volume-control position, wideband/A weighted in µV, input termination 1kHz, Lch | Rch:
    • At maximum: 132.1µV / 7.5µV | 132.8µV / 8.3µV
    • Unity gain: 132.8µV / 8.4µV | 138.5µV / 8.4µV
    • At minimum: 133.1µV / 9.0µV | 133.5µV / 9.0µV

Measurements Summary

General
The Bryston BP 6 C-Series line-level preamplifier, like so many units these days, is of a simple, basic design with a minimum of extra features.
A note on the measurements of this unit: Both channels measured very close to each other in all respects with the exception of the volume-control tracking, which, while better on some other preamps tested, was still quite acceptable.
Chart 1 shows the frequency response with the volume control set for unity gain for 0.5V input with instrument loading. In this chart, both channels are shown. The effect of the IHF loading is essentially negligible. The two channels are tracking within 0.4dB at this point on the volume control. The bandwidth of this unit (as defined by the -3dB points) is less than 10Hz to about 90kHz. Further, because the frequency response did not change noticeably with the volume set at maximum down to -70dB of attenuation, there is no Chart 2 to show these variations. Volume-control tracking between channels was within about 0.7dB down to -70dB of attenuation.
Chart 3 shows how total harmonic distortion varies with input level and frequency for both IHF and instrument loading with the volume control set for unity gain. In this design, there was no difference with instrument or IHF loading, a desirable attribute of circuit performance.
A spectrum of the distortion and noise residue of a 1kHz test tone at 0.5V output with IHF loading is plotted in Chart 4. AC-line-hum harmonics here are relatively low. At this output level, the signal harmonics are so low as not to be visible.

Chart 1 - Frequency Response at Unity Gain with IHF and Instrument Loading


Both channels shown with instrument loading
Red line = left channel
Blue line = right channel

Chart 2 - Frequency Response as a Function of Volume Control Setting



N/A

Chart 3 - Distortion as a Function of Output Voltage and Frequency


Instrument or IHF loading
Red line = 20Hz and 1kHz
Blue line = 20kHz

Chart 4 - Distortion and Noise Spectrum

Balanced output

IHF loading
Red line = spectrum of 1kHz test signal distortion and AC-line harmonics at 0.5V input and output at unity gain.
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4#
t T
发表于 2011-04-25 12:53 |显示全部

Conrad-Johnson ACT2

  • Measurements were made at 120V AC line voltage. Measurements made on the left channel unless otherwise noted.
  • Gain, volume at maximum:
        IHF loading, Lch/Rch = 10.49X, 20.4dB / 10.77X, 20.6dB
        Instrument loading, Lch/Rch = 9.98X, 20.0dB / 10.24X, 20.1dB
  • IHF sensitivity, input volts for standard IHF output of 0.5V:
        IHF loading, Lch/Rch: 50.1mV / 48.8mV
  • Output noise versus bandwidth and volume-control position, wideband/A weighted:
        At maximum, gain @ 99 = 557.9µV / 215.6µV
        Worst case, gain @ 99 = 557.9µV / 215.6µV
        Unity gain, gain @ 76 = 309.4µV / 20.6µV
        Listening level, gain @ 40 = 449.9µV / 5.4µV
  • AC line current draw at idle: 1.0A.
  • Output impedance at 1kHz: 516 ohms.
  • Input impedance at 1kHz:
        Gain at max (99), Lch/Rch = 67.1k ohms / 68.0k ohms
        Gain at 40, Lch/Rch = 12.0k ohms / 12.0k ohms
  • This preamplifier inverts polarity.

Measurements Summary

General
The Conrad-Johnson ACT2 preamplifier utilizes two 6N30P tubes in parallel for each channel, forming a single amplifying stage for its signal circuitry. A switched resistor network is used for the volume control. Solid-state regulators are employed to supply high voltage and heater voltages for the tubes.
Chart 1 shows the frequency response of the ACT2 with the volume control set for unity gain (76) for 0.5V input and IHF loading. The two channels are tracking within 0.25dB at this point on the volume control. Also shown in Chart 1 is the frequency response with an instrument load. The bandwidth with the instrument load is about 200kHz.
In Charts 2a and 2b, the frequency response of the preamp is shown for the volume at maximum (99) and at a typical listening position (40). Volume control tracking at these settings is also within about 0.25dB.
Chart 3 shows how total harmonic distortion varies with input level and frequency for both IHF and instrument loading. Unique in my experience is the identical nature of the distortion curves for 20Hz, 1kHz, and 20kHz. This is superb performance.
A spectrum of the distortion and noise residual of a 1kHz test tone at 0.5V output with IHF loading is plotted in Chart 4. AC line hum harmonics here are rather numerous. The signal frequency harmonics consist of just the second harmonic.

Chart 1 - Frequency Response at Unity Gain with IHF and Instrument Loading


IHF loading
Magenta line = left channel
Cyan line = right channel

Instrument loading
Red line = left channel
Blue line = right channel

Chart 2 - Frequency Response as a Function of Volume Control Setting

Chart 2A - gain at maximum (99)

IHF loading
Magenta line = left channel
Cyan line = right channel

Instrument loading
Red line = left channel
Blue line = right channel

Chart 2B - gain at 40

IHF loading
Magenta line = left channel
Cyan line = right channel

Instrument loading
Red line = left channel
Blue line = right channel

Chart 3 - Distortion as a Function of Output Voltage and Frequency


IHF loading
Magenta line = 20Hz, 1kHz, 20kHz

Instrument loading
Red line = 20Hz, 1kHz, 20kHz

Chart 4 - Distortion and Noise Spectrum


Red line = spectrum of 1kHz test-signal distortion and AC-line harmonics

  • 测量是在120V交流电压。 测量就左声道，除非另有说明。
  • 增益，音量开到最大：
        IHF型加载，廖创兴/ Rch的= 10.49X，二十○点四分贝/ 10.77X，二十〇点六分贝
        仪器装载，廖创兴/ Rch的= 9.98X，二十零点〇分贝/ 10.24X，二十点一分贝
  • IHF型灵敏度，标准IHF型的0.5V输出输入电压：
        IHF型加载，廖创兴/ Rch的：50.1mV / 48.8mV
  • 输出噪声与带宽和音量控制的位置，宽带/ A加权：
        在最大，增益@ 99 =557.9μV/215.6μV
        最坏的情况下，增益@ 99 =557.9μV/215.6μV
        单位增益，增益@ 76 =309.4μV/20.6μV
        听力水平，增益@ 40 =449.9μV/5.4μV
  • AC线在空闲电流消耗：1.0A的。
  • 在1kHz输出阻抗：516欧姆。
  • 在1kHz输入阻抗：
        在最大增益（99），廖创兴/ Rch的= 67.1k欧姆/ 68.0k欧姆
        增益为40，廖创兴/ Rch的= 12.0k欧姆/ 12.0k欧姆
  • 该前放颠倒极性。

测量综述

一般
康拉德-约翰逊ACT2的前置放大器每通道采用两个并联6N30P管，形成一个单一的信号放大电路，其阶段。 一个电阻网络交换用于控制音量。 固态稳压器是用来供应高压管，加热器电压。
图1显示了与增益为0.5V的输入和IHF型装（76）设置音量控制ACT2的频率响应。 这两个通道是在这个内跟踪0.25分贝卷上的控制点。 也显示在图1是负载与仪器的频率响应。 用仪器负载带宽约为200kHz的。
在图表2a和2b，该放大器的频率响应所示为最大（99）体积和一个典型的聆听位置（40）。 这些设置音量控制跟踪也是在大约0.25分贝。
图3显示了总谐波失真与输入水平和国际赫尔辛基人权联合会和仪器都加载频率各不相同。在我的经验是独一无二的失真曲线20Hz的，1kHz时，相同的性质和20kHz。 这是极好的表现。
一个对一个1kHz测试音失真和噪声残差在0.5V的输出频谱与IHF型装载在图4绘制。 在这里交流线路谐波，而众多的嗡嗡声。 信号的频率谐波只包括二次谐波。

图1 - 在单位增益频率响应IHF型和仪器载入


IHF型负荷
洋红色线条=左声道
青色线=右声道

装载仪器
红线=左声道
蓝线=右声道

图2 - 频率作为响应设置音量控制功能

图2A - 在最大增益（99）

IHF型负荷
洋红色线条=左声道
青色线=右声道

装载仪器
红线=左声道
蓝线=右声道

图2 B - 40的增益

IHF型负荷
洋红色线条=左声道
青色线=右声道

装载仪器
红线=左声道
蓝线=右声道

图3 - 频率失真，和一个函数的输出电压


IHF型负荷
洋红色线条= 20Hz的，1kHz时，20kHz的

装载仪器
红线= 20Hz的，1kHz时，20kHz的

图4 - 失真和噪声频谱


红线= 1kHz的光谱测试信号失真和AC -线路谐波
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5#
t T
发表于 2011-04-25 12:54 |显示全部

NuForce P-9

  • Measurements were made at 120V AC line voltage and on the left channel unless otherwise noted. Unity gain for instrument loading, balanced, and unbalanced output is 35 on front-panel display.
  • This preamplifier does not invert polarity.
  • AC line current draw
    • Standby: 0.11A
    • Operate: 0.13A
  • Input impedance at 1kHz:
    • Unbalanced input = 20.7k ohms
  • Output impedance at 1kHz:
    • Unbalanced output = 95.0 ohms
    • Balanced output = 95.0 ohms
  • Gain, balanced output, volume at maximum:
    • Instrument loading, Lch/Rch = 2.40X, 7.6dB / 2.44X, 7.8dB
    • IHF loading, Lch/Rch = 2.37X, 7.5dB / 2.41X, 7.6dB
  • Gain, unbalanced output, volume at maximum:
    • Instrument loading, Lch/Rch = 2.39X, 7.6dB / 2.43X, 7.7dB
    • IHF loading, Lch/Rch = 2.37X, 7.5dB / 2.41X, 7.6dB
  • IHF Sensitivity, input volts for standard IHF output of 0.5V, IHF loading:
    • Balanced output, Lch/Rch = 211.0mV / 207.5mV
    • Unbalanced output, Lch/Rch = 2.11.0mV / 207.5mV
  • Output noise versus bandwidth and volume-control position:

    • Balanced output, at maximum, Lch | Rch, wideband/A weighted =
      120.0µV / 42.4µV | 68.6µV / 16.0µV
    • Balanced output, at unity gain, Lch | Rch, wideband/A weighted =
      163.2µV / 64.2µV | 49.6µV / 7.8µV
    • Balanced output, at typical listening level (20dB below unity gain), Lch | Rch, wideband/A weighted =
      163.2µV / 64.2µV | 49.6µV / 7.8µV
    • Balanced output, at minimum, Lch | Rch, wideband/A weighted =
      148.6µV / 52.4µV | 44.0µV / 7.1µV

    • Unbalanced output, at maximum, Lch | Rch, wideband/A weighted =
      76.7µV / 15.9µV | 69.6µV / 15.6µV
    • Balanced output, at unity gain, Lch | Rch, wideband/A weighted =
      87.1µV / 12.5µV | 71.9µV / 12.2µV
    • Unbalanced output, at typical listening level (20dB below unity gain, Lch | Rch, wideband/A weighted =
      91.4µV / 8.0µV | 59.8µV / 7.8µV
    • Unbalanced output, at minimum, Lch | Rch, wideband/A weighted =
      92.3µV / 7.0µV | 54.8µV / 7.3µV

Measurements Summary

General
The NuForce P-9 line-level preamplifier is a new product offering from a company recently well known for its switching power amplifiers.
Chart 1 shows the frequency response in the unbalanced I/O mode with the volume control set for unity gain for 0.5V input with instrument and IHF loading. The closest front-panel gain setting for this is 35. In this chart, both channels are shown. The effect of the IHF loading is essentially negligible and the two channels are tracking within about 0.2dB at this point on the volume control.
The rise in high-frequency response is suggestive of a peak beyond 200kHz. Results were the same for the balanced outputs.
In Chart 2, for the gain set to maximum, the very high-frequency response now rolls off a bit. This change in response happens between the unity-gain and the maximum-gain settings. For all gain settings down to about –50dB, the response looks like in Chart 1. Volume-control tracking between channels was mostly within a few tenths of a dB down to –50dB, except at around –20dB, where the error was about 1dB. At volume settings greater than 50dB below unity gain, the channel tracking quickly deteriorated and was off by about 3dB at –60db below unity gain.
Chart 3A shows how total harmonic distortion varies with input level and frequency for instrument loading in the unbalanced I/O mode. With IHF loading, the results were the same. This circuit has some increase in distortion at the higher output levels at 20kHz that would be inconsequential at normal output levels. In Chart 3B, the results for the balanced output with instrument loading are shown. Again, there is no real difference with IHF loading. The actual signal distortion is very low in this design and is dominated by line harmonic and random noise up to about 2V output – enough to drive most power amplifiers to over 100W output power.
A spectrum of the distortion and noise residual of a 1kHz test tone at 0.5V output with instrument loading is plotted in Chart 4 for the balanced output. AC-line hum harmonics here are prominent, and no signal-frequency harmonic components are visible above the noise floor.

Chart 1 - Frequency Response at Unity Gain with IHF and Instrument Loading

Unbalanced output

IHF loading
Magenta line = left channel
Red line = right channel

Instrument loading
Red line = left channel
Blue line = right channel

Chart 2 - Frequency Response as a Function of Volume Control Setting

Gain at maximum

Instrument loading
Red line = left channel
Blue line = right channel

Chart 3 - Distortion as a Function of Output Voltage and Frequency

Unbalanced output

Instrument loading
Red line = 1kHz
Blue line = 20Hz
Magenta line = 20kHz

Balanced output

IHF loading
Red line = 1kHz
Blue line = 20Hz
Magenta line = 20kHz

Chart 4 - Distortion and Noise Spectrum

Balanced output

Instrument loading
Red line = spectrum of 1kHz test signal distortion and AC-line harmonics at 0.5V input and output at unity gain.

  • 测量是在120V交流线路电压和左声道，除非另有说明。 单位增益仪器装载平衡，非平衡输出和前面面板显示屏35。
  • 此前置放大器不颠倒极性。
  • 交流线电流
    • 待机时：0.11A
    • 操作：0.13A
  • 在1kHz输入阻抗：
    • 欧姆非平衡输入= 20.7k
  • 在1kHz输出阻抗：
    • 非平衡输出= 95.0欧姆
    • 平衡式输出= 95.0欧姆
  • 增益，平衡输出，音量开到最大：
    • 仪器装载，廖创兴/ Rch的= 2.40X，七点六分贝/ 2.44X，七点八分贝
    • IHF型加载，廖创兴/ Rch的= 2.37X，七点五分贝/ 2.41X，7.6分贝
  • 增益，不平衡输出，音量开到最大：
    • 仪器装载，廖创兴/ Rch的= 2.39X，七点六分贝/ 2.43X，七点七分贝
    • IHF型加载，廖创兴/ Rch的= 2.37X，七点五分贝/ 2.41X，7.6分贝
  • IHF型灵敏度，标准IHF型输出0.5V的IHF型负载，输入电压：
    • 平衡输出，廖创兴/ Rch的= 211.0mV / 207.5mV
    • 非平衡输出，廖创兴/ Rch的= 2.11.0mV / 207.5mV
  • 输出噪声与带宽和音量控制的位置：

    • 平衡输出，在最大，廖创兴| Rch的，宽带/ A加权=
      120.0μV/42.4μV|68.6μV/16.0μV
    • 平衡输出，在单位增益，廖创兴| Rch的，宽带/ A加权=
      163.2μV/64.2μV|49.6μV/7.8μV
    • 平衡输出，在典型的听力水平（低于20dB的增益），廖创兴| Rch的，宽带/ A加权=
      163.2μV/64.2μV|49.6μV/7.8μV
    • 平衡输出，至少，廖创兴| Rch的，宽带/ A加权=
      148.6μV/52.4μV|44.0μV/7.1μV

    • 非平衡输出，在最高，廖创兴| Rch的，宽带/ A加权=
      76.7μV/15.9μV|69.6μV/15.6μV
    • 平衡输出，在单位增益，廖创兴| Rch的，宽带/ A加权=
      87.1μV/12.5μV|71.9μV/12.2μV
    • 非平衡输出，在典型的听力水平（低于单位增益，20dB的症| Rch的，宽带/ A加权=
      91.4μV/8.0μV|59.8μV/7.8μV
    • 非平衡输出，至少，廖创兴| Rch的，宽带/ A加权=
      92.3μV​​/7.0μV|54.8μV/7.3μV

测量综述

一般
该NuForce的P - 9线级前置放大器是一个很好的从最近的开关功率放大器知名公司新产品系列。
图1显示了不平衡本人频率响应/与增益为0.5V的仪器和IHF型与装载量控制输出输入模式。最近的前面板增益此设置为35。 在此图表，显示两个通道。 作者：IHF型负载效应基本上是忽略不计，这两个通道是在大约0.2dB的跟踪在此卷上的控制点。
在高频率响应崛起是一种超越200kHz的高峰暗示。 结果是相同的平衡输出。
在图2，增益设置到最大，非常高的频率响应现在卷筒一点点。 这种变化发生反应之间的团结增益，最大增益设置。 对于所有增益设置下降到约- 50dB的，反应好像在图1。 音量控制通道之间的跟踪主要是在一个十分之几分贝下降到五○分贝，除了约- 20dB的，那里的误差为1dB的。 在大于50dB的增益音量设置下，渠道跟踪迅速恶化，并关闭了约3分贝以下单位增​​益在- 60dB的。
图3a显示了总谐波失真与输入水平和仪器加载频率在不平衡的I / O模式各不相同。 随着IHF型载荷，结果都是一样的。 该电路中有一些在较高的产出水平失真20kHz的，将在正常产出水平微不足道的增加。 在图3 B，对于与仪器负荷平衡输出的结果显示出来。 同样，也没有真正的区别与IHF型负荷。 实际的信号失真非常低，这种设计主要是由线路谐波和随机噪声高达约2V的输出 - 足以驱动器超过100W的输出功率最功率放大器。
一个对一个1kHz测试音失真和噪声与残留在0.5V的输出频谱仪装载在图4绘制的平衡输出。交流线路的谐波这里​​有著名的嗡嗡声，没有信号的频率谐波成分高于本底噪声可见。
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leslie

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  • 19720110
  • 27155
  • 28495
  • 2003-01-24
6#
t T
发表于 2011-04-25 12:55 |显示全部

Rogue Audio Metis

  • Measurements were made at 120V AC line voltage.
  • Gain:
    • Line section, Lch/Rch = 4.62X, 13.3dB / 4.36X, 12.8dB
    • Phono section (at 1kHz) = 76X, 37.6dB
  • Output noise versus bandwidth and volume-control position, wideband/A weighted:
    • Volume control turned CCW, wideband, Lch/Rch = 0.23mV / 0.24mV
    • Volume control turned CCW, A weighted, Lch/Rch = 0.032mV / 0.060mV
    • Volume control at reference (unity gain), wideband, Lch/Rch = 0.24mV / 0.27mV
    • Volume control at reference (unity gain), A weighted, Lch/Rch = 0.037mV / 0.058mV
    • Volume control turned CW, wideband, Lch/Rch = 0.74mV / 0.75mV
    • Volume control turned CW, A weighted, Lch/Rch = 0.057mV / 0.058mV
  • Phono referred input noise, 1k-ohm source impedance:
    • Wideband, Lch/Rch = 11.4µV / 3.0µV
    • A weighted, Lch/Rch = 3.7µV / 0.91µV
  • AC line current draw at idle: 0.27A
  • Output impedance at 1kHz:
    • Line section = 720 ohms
    • Phono section (at fixed outputs) = 39 ohms
  • Input impedance at 1kHz:
    • Line section = 150k ohms
    • Phono section (paralleled with 150pF) = 47k ohms
  • Phono overload at 1kHz = 106mV
  • This preamplifier line section inverts polarity; the phono preamp section does not invert polarity.

Measurements Summary

General
The Rogue Audio Metis preamplifier utilizes two octal-based 6SN7 tubes in its line-section signal circuitry. The phono circuitry is implemented with a dual op-amp.
Chart 1 shows the frequency response of the Metis for both channels with the volume control set for unity gain and with instrument and IHF loading. With the IHF load, the high-frequency response is unaffected, but the low-frequency response starts to roll off due to the size of the output coupling capacitors and the relation to the 10k IHF loading. Generally, this preamp’s high-frequency response is at its worst at full volume and gets better as the volume is turned down.
At full gain with the volume fully up, Chart 2A shows the most high-frequency roll-off. With the volume control set at an attenuation of about –30dB, which is where the volume would likely be set for typical listening, the response is much flatter, as shown in chart 2B. Volume-control tracking between channels was within 0.8dB down to –60dB attenuation. Note that in chart 2B tracking between channels is particularly close.
Chart 3 shows how THD+N (total harmonic distortion plus noise) varies as a function of preamp output level. The volume control is set for unity gain. In this particular case, the curves were only a little different for the three test frequencies of 20Hz, 1kHz, and 20kHz, and for instrument and IHF loading. This is good for the distortion to be essentially independent of frequency and loading. The curve shown in Chart 3 is typical for the various frequencies and loading.
With the volume control again set for unity gain, a plot of the 1kHz distortion at 0.5V output is shown in Chart 4. Results for this test were about the same for instrument or IHF loading.
Because this preamp has no tone controls, there is no Chart 5 to display the tone-control characteristics.
RIAA equalization error for the phono preamp is plotted in Chart 6. The two channels differ above 1kHz, but the overall error is quite acceptable.
Phono THD+N versus output voltage and frequency is shown in Chart 7 for instrument loading. With the IHF load, instability set in between 2-3V, which prevented getting the curve data for that condition.

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 - volume at maximum (0dB)

Instrument loading
Red line = left channel
Magenta line = right channel

Chart 2B - volume at -31dB

Instrument loading
Red line = left channel
Magenta line = right channel

Chart 3 - Distortion as a Function of Output Voltage and Frequency


Instrument loading

Red line = 20Hz, 1kHz, 20kHz

Chart 4 - Distortion and Noise Spectrum


Red line = spectrum of 1kHz test-signal distortion and AC-line harmonics at 0.5V input and output

Chart 6 - Phono-Stage RIAA Equalization Error


Instrument loading

Red line = left channel
Magenta line = right channel

Chart 7 - Phono-Stage Distortion vs. Frequency and Output


Instrument loading

Red line = 1kHz
Magenta line = 20Hz
Blue line = 20kHz

  • 测量是在120V交流电压。
  • 增益：
    • 线部分，廖创兴/ Rch的= 4.62X，13.3分贝/ 4.36X，一十二点八分贝
    • 唱机节（1kHz时）= 76X，三十七点六分贝
  • 输出噪声与带宽和音量控制的位置，宽带/ A加权：
    • 音量控制逆时针转，宽带，廖创兴/ Rch的= 0.23mV / 0.24mV
    • 逆时针转音量控制的加权，廖创兴/ Rch的= 0.032mV / 0.060mV
    • 音量控制在参考（单位增益），宽带，廖创兴/ Rch的= 0.24mV / 0.27mV
    • 音量控制在参考（单位增益），一个加权症/ Rch的= 0.037mV / 0.058mV
    • 音量控制转向顺时针，宽带，廖创兴/ Rch的= 0.74mV / 0.75mV
    • 音量控制变成连续的加权，廖创兴/ Rch的= 0.057mV / 0.058mV
  • 提到唱机输入噪声，1K的欧姆源阻抗：
    • 宽带，廖创兴/ Rch的=11.4μV/3.0μV
    • 一个加权，廖创兴/ Rch的=3.7μV/ 0.91 μV的
  • 交流线电流消耗在怠速：0.27A
  • 在1kHz输出阻抗：
    • 行部分= 720欧姆
    • 唱机部分（固定输出）= 39欧姆
  • 在1kHz输入阻抗：
    • 行部分= 15万欧姆
    • 唱机条文（与150pF并联）=有47K欧姆
  • 唱机超载在1kHz = 106mV
  • 该前放线部分反转极性;唱机放大器节不颠倒极性。

测量综述

一般
盗贼利用其前置音频梅蒂斯线区间信号电路两个八进制为基础的6SN7管英寸 唱机电路实现了双运算放大器 。
图1显示了与单位增益和仪器和IHF型加载设置音量控制两个渠道，梅蒂斯频率响应。 随着IHF型负荷，高频率响应不受影响，但低频响应开始下线，由于输出耦合电容的大小和对装载的10k IHF型的关系。 一般来说，这个前置放大器的高频响应是最糟糕的全量，取得了较好的音量被拒绝。
在与全增益量完全达到，图2a显示最高频滚降。 与AT约- 30dB的衰减，这就是量很可能会设置为典型的聆听音量控制设置，响应比较平缓，见图2b所示。 音量控制，通道间是在0.8dB的跟踪低至- 60dB的衰减。 请注意，在图2b通道之间特别密切跟踪。
图3显示了如何的THD + N（总谐波失真加噪声）作为前置放大器的输出电平的函数变化。音量控制设置为单位增益。 在这个特殊的情况下，曲线只有一个20Hz的三个，1kHz时，和20kHz测试频率略有不同，仪器仪表及国际赫尔辛基人权联合会和加载。 这很好，因为在本质的扭曲和加载频率无关。 在图3所示的曲线是由不同频率和负载的典型。
再次与音量控制设置统一增益，在1kHz的失真0.5V输出图在图4所示。 此测试结果进行有关仪器或IHF型加载相同。
因为这没有前置音调控制，没有图5显示音频控制特性。
美国唱片业协会的唱机放大器均衡误差在图6曲线。 两个以上不同1kHz的渠道，但总体误差是完全可以接受。
唱机的THD + N与输出电压和频率显示在图7仪器加载。 随着IHF型负载，不稳定之间设置2 - 3V的，这妨碍了这一条件得到的曲线数据。
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