Since I gave this presentation at the Rocky Mountain Audio Fest in October 2012, based on one of the topics in my Richard C. Heyser Memorial Lecture and mentioned in my March 2013 "As We See It," I have repeated it at Music Matters evenings at Definitive Audio in Seattle and Listen-Up in Denver, and at audiophile society meetings in Minneapolis, California's Central Coast, and Connecticut. I will be repeating the presentation at a Music Matters event at Georgia retailer Audio Alternative, Wednesday April 24, at 6pm, at T.H.E. Show Newport…
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Immedia introduced the German Audio Physic speakers at the 1994 Winter CES. As I mentioned in my Show report (Vol.17 No.4), I felt the price:performance ratios of the three models displayed was an indirect one: the least-expensive—the Step—sounded best (footnote 1). Since I'm always looking for products that offer great bang for the buck, I arranged to receive a pair of review samples.
The speakers looked innocuous at first glance: typical minimonitors with two drivers—a ¾" metal-dome tweeter and a tiny woofer with a chassis just 4" across—and a rear-firing port 1.25" in diameter. But the…
Sidebar 1: Specifications
Description: Two-way, ported, stand-mounted loudspeaker. Drive-units: 4" (102mm) plastic-cone woofer, 0.75" (19mm) metal-dome tweeter. Measured frequency response: 60Hz–20kHz ±3dB. Measured sensitivity: 84dB/W/m. Measured impedance: 5 ohms nominal; 3.3 ohms minimum.
Dimensions: 13" (330mm) H by 5.5" (140mm) W by 9" (229mm) D.
Serial numbers of review samples: 416A/416B.
Price: $1395/pair (1994); no longer available (2013). Necessary stands were available from Sound Anchors for $210/pair (1994). Approximate number of dealers: 15.
Manufacturer:…
Sidebar 2: Measurements
The Step was moderately sensitive for a tiny speaker, at an estimated 84dB/W/m (B-weighted). Its impedance characteristic, however, will make demands on the partnering amplifier, as shown by the plot of impedance magnitude and phase against frequency (fig.1). The magnitude drops below 4 ohms throughout the lower midrange, reaching a minimum value of 3.4 ohms at 200Hz. In the treble, however, the impedance stays above 10 ohms. The shape of the plot suggests that tube amplifiers with high output impedances will make the Step sound up-tilted. There are a few wrinkles…
In April 1987, Anthony H. Cordesman had mixed feelings about the Mod Squad Passive Line Drive System Control Center. (Read his review here.) Introduced in 1984, the Line Drive offered volume and balance controls, five line-level inputs, and switching and monitoring for two tape decks. You didn't plug it into the wall; it provided no gain. Was it even a proper preamp? (footnote 1)
AHC demurred. "I'm not sure that I'm ready to advise anyone to take the risk of not buying a unit with a top-quality phono stage, no matter how well CD or DAT perform," he concluded, between commenting on Middle…
I've also tried various so-called passive preamps—including those that use transformers. These are usually called transformer volume controls (TVC), or magnetic passive preamplifiers. Generally speaking, they use an auto-transformer designed so that the user can tap in to different sections of its windings via a switch. As each section is engaged, the voltage level swings up or down, as does the output impedance.
There are several advantages to this. A transformer acts to isolate your power amp from whatever radio-frequency interference (RFI) your source components are trying to send it…
Sidebar: Specifications
Description: Passive control preamplifier. Standard fittings: two balanced XLR inputs, four unbalanced RCA inputs, and one pair each of balanced XLR and unbalanced RCA outputs.
Dimensions: 9.75" (250mm) W by 3.4" (88mm) H by 10.1" (260mm) D.
Fimishes: Black, clear anodized, blue, or red faceplate.
Price: £5000 ($7800 at time of writing).
Manufacturer: Music First Audio, 20/23 Innovation Centre, Highfields Drive, Churchfields, St. Leonards on Sea, East Sussex TN38 9UH, England, UK. Tel: (44) (0)1424-858260. Web: www.mfaudio.co.uk. US Distributors:…
With Peachtree Audio's new nova125 integrated amplifier, most decisions are made for you.
Need a DAC with three S/PDIF inputs (two coax, one optical)? An asynchronous USB DAC? A line stage? A tubed output buffer? A power amp that should be able to drive even difficult speaker loads? Remote control? You've got them all for $1499. Just add speakers. (I assume you have a laptop computer and several disc spinners.) You may want a separate phono stage, because there is none onboard.
While well furnished with digital inputs, the nova125 has only one pair of RCA line-level analog inputs…
Class-D amplifiers for serious audio listening are now offered by the likes of Cary Audio, Mark Levinson, Micromega, and Jeff Rowland Design Group—not to mention newcomers like Nuforce. And there's no reason a switching power supply can't be used with tubed amplifiers—even single-ended ones such as the MiniWatt N3 integrated ($349). I'll leave it to the tech types to carry on the discussion.
I'll take mine on the rocks
Peachtree Audio's nova125 uses an ASX250 module from ICE, who developed it in Denmark. The company is part of Bang und Olufsen. The folks at Peachtree Audio love the…
Sidebar : Specifications
Description: D/A integrated amplifier with three S/PDIF inputs (two coax, one optical), one USB port (Asynchronous up to 24/192), one pair of analog inputs, one pair preamp outputs. Preamp tube: 6N1P. Maximum power: 125Wpc into 8 ohms (20.25dBW), 220Wpc into 4 ohms (20.2dBW). Frequency Response: 20Hz–20kHz, ±0.5dB. Voltage gain: 24dB. Dynamic Range: 121dB. Sensitivity for maximum output: 1.2V. Input Impedance: 50k ohms. Output impedance: 18m-ohms. Minimum Load: 2 ohms. Damping Factor: >1000 (100Hz. 8 ohms). Max Output Current: 30A; Channel Tracking: <0.2dB…