The output transformer is probably the major element involved. Of the compensation scheme the amplifier uses to ensure high-frequency stability The situation reverses at aboutġ20 kHz, where the output impedance becomes positive again. The out put increases for de creasing loads. (at about 60 kHz), the output impedance be comes negative when this happens, Technically, where the curves first cross Varies very little with changes in load, an indication that the Power-3's Across the audio band and beyond, the output I used their balanced or unbalanced inputs.įrequency response, at the 8-ohm taps at a 2.83-volt output (1 watt intoĨ ohm), is shown in Fig. Gain on the 8-ohm taps was 25.75 dB for amp A and 25.95 dB for amp B, whether As an example of how close the match was, voltage Most respects, so I'm presenting data for the one I've designated amp A, The performance of the two Power-3s I received matched quite closely in Wrought through countless hours of listening evaluation and circuit` tweaking, But Sonic Frontiers'Ĭombination of these elements, using modern components together with refinements Highlights") in various other amplifiers over the years. I have seen most of the Power-3's basic circuit elements (see "Circuit The insulation on the internal wiring appeared to be of Teflon. beards, high-quality components abound (e.g.,Ĭapacitors from MIT, Solen, and Wima and resistors from Caddock and IRC). Metalwork is first-rite, with Pemm nuts and machine screws fastening the Their chassis, the Power-3 has most of its components mounted to the undersidesĪll in all, the Power-3 is beautifully made and attractive. A smaller board under the transformer enclosure holds Liberally drilled to allow air drawn up through the bottom plate to pass Holds all the tube sockets and most of the audio circuit ry. The amplifier'sīottom plate is slotted to al low cool air to enter. A slotted metal cage fits over the tubes, giving the amplifier a simpleīox shape the cage is attached to the chassis with captive screws. It is a small band, about 1 1/4 inches wide, that is slotted to help coolĪ number of heat sinks for power-supply components that are just below theīand. Between the chassis and the transformer enclosure behind The Power-3's audio circuitry is in a stainless-steel chassis extendingįorward from the transformers' enclosure, and the tubes extend through the The bias-setting circuitry for the output tubes. The input selector mutes the Power-3, shorts all of its inputs, and activates The other serves as the inverting unbalanced in put. One of these RCA jacks also serves as the noninverting unbalanced input Signals can be fed in through an XLR connector or a pair of RCA jacks. (single-ended) noninverting input, or unbalanced inverting input. The only features on that panel are pushbutton switchesĪnd indicator LEDs for "Standby" and "Power."Īnd output transformers and the filter capacitors are in a rectangularĮn closure at the back of the Power-3, which also forms the amp's rear panel.Ī switch near the input jacks on this panel selects balanced input, unbalanced Like most Sonic Frontiers components, the Power-3 is available with a black (The UPS guy who delivered these 100-pound amps was not delighted.) I was surprised and delighted when a pair of 220-watt Power-3s arrived on Top-of-the line amplifier, I expected to get the Power-2 stereo amp. Though I had hoped to get the mono Power-3, the company's I was impressed enoughīy its amps at the 1994 Winter Consumer Electronics Show to ask for a chance Player in high-end audio for a number of years. I have followed the rise of Sonic Frontiers as a major D (46 cm x 23 cm x 56 cm).Ĭompany Address: 2790 Brighton Rd., Oakville, Ont., Canada L6H 5T4 Rated Power Output: 220 watts into 8-, 4-, or 2-ohm load.ĭimensions: 18 in. 1996) Home | Audio Magazine | Stereo Review magazine | Good Sound | Troubleshootingĭepartments | Features | ADs | Equipment | Music/Recordings | History 1996) Sonic Frontiers Power-3 Mono Amp (Equip.
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