Basic Amplifier Measurement Techniques Audioholics. An Overview to Audioholics Power Amplifier Measurements. There has been much discussion on the major audio forums lately regarding AV receivers and multi channel amplifier power output capabilities as well as their abilities to drive low impedance loads. Much of the controversy steams around the infamous All Channels Driven Test which simulates a best case test load in a worst case environment and by all intents and purposes an unrealistic real world scenario. For more information on this, the reader is encouraged to read the following articles All Channels Driven Test Does your Amp DeliverThe All Channels Driven Test Controversy. Product Managing Receiver Platforms With that, lets all first remember that receivers in the 1k price range from the leading companies today are an absolute bargain regarding their processing power, features, and performance. I like to think of them as an excellent PreampProcessor usually rivaling many costlier PrePros with a free amp thrown in. Whether the amp section within the said receiver is good enough depends on the following variables Loudspeaker Impedance Loudspeaker Efficiency Room Size Room Acoustics Listening Preferences Whether or not you apply bass management to your Loudspeakers and utilize a dedicated powered subwoofers. As you can see, there are a number of variables and the answer is simply not that straight forward. When conducting amplifier measurements, we tend to be a bit more forgiving with receivers than multi channel power amplifiers for obvious reasons. Yes, look for sweet potatoes that are labeled organic. Nonorganic sweets are often treated with a sproutsupressing chemical, and we want these sweets to sprout Issuu is a digital publishing platform that makes it simple to publish magazines, catalogs, newspapers, books, and more online. Easily share your publications and get. The Bughouse. By Daniel Swift. In 1945, the American poet Ezra Pound was due to stand trial for treason for his broadcasts in. Most arent designed to deliver rated power with all channels driven and most dont make any claims that they are. As a result of all this dialogue, we have come up with a fair and equitable way of measuring power amplifier performance that not only tests rated power, but other aspects which directly affects how it will sound when powering various loudspeaker loads. Before. I felt it relevant. I am the primary reviewer that measures amplifier performance for the Audioholics publication. My Background as an Electrical Design Engineer. After graduating college with my B. S. E. E. degree in Electrical Engineering, I went and worked for a. I designed analog front end and analog filters for DSL and phone applications. I also worked for a government defense. I designed audio communication systems for NAOC, Air Force One. White House.   I sleep well at night knowing if our President orders a nuclear strike from NAOC, all of the generals will clearly hear and understand his orders because of my design efforts on the audio products used in that battle airplane. My analog background. While doing design work, I always. I. learned as a degreed Electrical Engineer in college and a Senior Design. Engineer in my profession. Editorial Note on the Scientific Process Used for Product Development. Step 1 Hand Calculations amp. Circuit Analysis. I first started with a design concept on paper doing calculations based on. Step 2 Build Simulate Circuit. Models. I then simulated the circuits using a program called PSPICE. I often had to. build my own simulation models for parts that werent in the parts library. Step 3 Build and Measure Actual Lab. I then built up test circuits in the lab to measure circuit performance. Step 4 Correlate data from Steps. Once I had a positive correlation between my hand design, PSPICE simulation and. Lab performance, I then went on to spin a PWB to produce a full fledged prototype. The measurements I made in the lab had a. My bosses expected me to show. Audioholics Amplifier Measurements Overview Interview. Why Does Audioholics Measure Amplifier Performance Personally. Audioholics Amplifier Measurements. Evolution. When we first started Audioholics, we only had an analog oscilloscope. It was a rather tedious and crude. Then we became fortunate to acquire an Audio Precision SYS2. Audio Analyzers. Recently weve replaced the venerable SYS2. The Hindu Editorial 2013 Pdf. AP APx. 58. 5 HDMI Analyzer which tests up to 8 channels. Ever since using the APx. The APx. 58. 5 doesnt come cheap. In fact the version we have represents a 4. We dont know of any other AV publication that is this committed to having the very best hardware to do amplifier measurements and only one amplifier manufacturer to our knowledge Emotiva that has made such a significant investment in analog test equipment. The Measurements. Lets continue on and establish all of the relevant test criteria for gauging amplifier performance. Quantifying the measured results of the data below will directly determine just how well the amplifier performs and if it meets manufacturers specifications. Frequency Response. Hz to 2. 0k. Hz 0d. B. We test Frequency Response at all power levels and 8. We have seen poorly designed receiver amplifiers that simply lose power bandwidth when driving 4 ohm loads at full power. In such cases, we caution users to stick with 8 ohm rated speakers. Since we never know what speaker a consumer is using, we. The design goal for any good amplifier should exhibit ruler flat frequency response from 2. Hz to 2. 0k. Hz with less than. B of variation in that entire audio passband. We also check for channel to channel variation which to ensure each channel will play at similar volume levels given identical input source material. An amp. that exhibits frequency peaking at high frequency can sound bright. There are exceptions to this rule in cases. Class D amplifier output filters can cause varying response. Emotiva UPA 7 left pic Axiom Audio A1. Amplifier Gain this is a measure of how much output voltage you will get given a fixed input voltage where Av VoutVin. Amplifier gain Av is also measured to ensure it will be compatible with any. We like to see power amplifiers hit. Vrms or less as many AV receivers preouts have. If the power amp requires more than 2. Vrms to hit. rated power and the preamp cant deliver it, then the result will be a. If an amplifier has unbalanced and balanced inputs, we like to see that they follow the THX Guidelines which is adopted from the pro audio world where Unbalanced Av 2. B THX. standardBalanced AV 2. B 6 d. B lower. than unbalancedThe reverse should be true for preamps so that the output level when switching between balanced and unbalanced connections between the preamp and power amp remains constant. THD and IMD Distortion This is a measure of how well an amplifier can faithfully reproduce a signal without introducing any artifacts or harmonics. While this is an important metric to consider, most solid state amps these days boast pretty low figures here usually well below audibility and are rarely a real world problem for well designed amplifiers. In addition, distortion measurements into a resistive load are generally good on amplifiers. Reactive load distortion testing is rarely done, but of interest if a quality load could be constructed and not act as the distortion mechanism. This will be revisited at a later date and incorporated into this test procedure when appropriate. Emotiva UPA 7 1k. Hz. Power Sweep vs Distortion 1k. Hz PSweepWe do look at distortion at 1 watt and full rated power. We consider the fidelity firewall to be 0.