AI-501DA OVERVIEW High-Quality Sound in a Modern Hi-Fi System – The Smarter Way Integrated Amplifier with 192kHz USB Audio Input and Low Power Consumption. The DMA-360 Monaural Reference Amplifier. The DMA-360 Monaural Reference Amplifier is the first limited production monaural amplifier from Spectral Audio. The all-triode REX II power amplifier represents a technological tour de force of modern engineering applied to vacuum-tube power-amplifier design. Basic Amplifier Measurement Techniques . For more information on this, the reader is encouraged to read the following articles: All Channels Driven Test - Does your Amp Deliver? The 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 Preamp/Processor (usually rivaling many costlier Pre/Pros) with a free amp thrown in. Whether the amp section within the said receiver is . Most aren't designed to deliver rated power with all channels driven and most don't make any claims that they are. I often had to. build my own simulation models for parts that weren't 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. My bosses expected me to show. Audioholics Amplifier Measurements Overview Interview. Why Does Audioholics Measure Amplifier Performance? Personally. we believe measuring amplifier performance for reviews has two purposes: ensures the manufacturer claims. 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 we've replaced the venerable SYS2. AP APx. 58. 5 HDMI Analyzer which tests up to 8 channels. Ever since using the APx. 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. There are exceptions to this rule in cases. Class D amplifier output filters can cause varying response. 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. We take it one step further and look at FFT Distortion of an amplifier at 1 watt and full rated power. THD Distortion Ratio vs Frequency - It's good housekeeping to sweep distortion vs frequency to see how the amplifier performs for the entire audio bandwidth instead of the typical discrete 1k. Hz single test tone. Some people prefer the distortion profile of a tube. It's not our place to judge. Emotiva UPA- 7 FFT Distortion. SMPTE Intermodulation Distortion We just started including SMPTE IMD multi- tone distortion tests to see how amplifiers react to non harmonically related signals. We tested power using three methods all of. THD + N: Continuous. Full Power Bandwidth (CFP- BW) from 2. Hz to 2. 0Khz into 8 and 4- ohm loads (up to. Hz. Power Sweep vs Distortion (1k. Hz PSweep) - popularized by the print magazines. Hz. This is the test most manufacturers (and many print publications) do when rating their amplifiers . It does provide an instant gratification number for. Our measurements are. A line with no Variac to regulate. Many amplifier manufacturers publish their SNR figures at full power, which can be misleading and hard to compare between different amplifiers at differently rated power levels. Many also apply weighting filters to yield better results such as A- wt or C- wt. This can make over a 1. B difference compared to unweighted measurements and should be noted when comparing various amplifiers. It is best to look at 1 watt levels (where the amp spends most of its time) and interpolate the SNR at the amplifier's full rated power. Unless we are measuring Class D amplifiers, we apply no weighting in our SNR measurements. We take it one step further and do All- to- One crosstalk measurements. This measures stereo separation. Usually lower is better, but some do prefer high output impedance tube amps for example since they can excessively roll off high frequency response and result in a warm sound. Note: sonically preferring something doesn't necessarily mean its more accurate or precise. We used to show these measurements in older reviews, but since we. We only now publish output impedance if we find it to. A very high output impedance such as those found in tube. Class D amps with minimal post filter feedback can drastically affect. A low output. impedance ensures an amp will sound more consistent regardless of the load. Axiom A1. 40. 0- 8 Output Impedance Damping Factor - This specification is somewhat overstated by most manufacturers and the reader is encouraged to reference our article: Damping Factor - Effects on System Response. In real world scenarios, cable impedance usually. I still like to check for this if we also measure output impedance, as. How we hear/perceive sound is a different. Sound is as much of an. That being said, it's important to note we do all of my listening tests of. BEFORE conducting any measurements. This ensures we are NOT pre- biased by a. In such instances that is. Our ears are far more forgiving than our test. Its because of our rigorous testing methodology that many of the big. Beta testing of their. I've also worked very. Audio Precision to devise better testing methods. I am still working on refining them even further. We hope to do reactive load. I am always evolving our testing procedure. I also recommend you watch the Audio Precision Seminar about measuring amplifiers they gave at our last annual SOTU event held at Disneyworld. Record these results in Table 1. Do NOT vary amplitude of the function generator, only Frequency. Rdc = 8. 0. 4 ohms ; Ls = 5. Rdc = 4. 0. 3 ohms ; Ls = 3.
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