Nagra Pyramid Power Amps

I've known the name Nagra for decades, but only in the realm of professional audio, especially field recorders. Recently, I learned that the Swiss stalwart also offers a line of high-end consumer electronics, such as the Pyramid Monoblock Amplifier (PMA) and Pyramid Stereo Amplifier (PSA).

Where the names come from is obvious, but it's what's under the pyramid that counts. Both models offer solid-state class-AB operation—the PMA provides 200 watts RMS into 8Ω with a frequency response from 10Hz to 70kHz (+0/-3dB), THD under 0.09% at full power, and SNR typically 104dB, while the PSA divides the power between two channels (100Wpc) with otherwise identical specs. In addition, both feature Nagra's Power Factor Corrector (PFC) power supply, which "follows" the current coming from the input transformer and cleans it up before sending it to the amplification circuitry.

You can configure the PMA to accept balanced or unbalanced inputs, while the PSA is limited to balanced inputs. A switch on both enables or disables the auto-on function, which turns the amp on when it receives a signal and shuts it down after 15 minutes of silence. This is especially helpful when the amps are inaccessable—though they are attractive enough to want them visible.

Nagra gear is anything but cheap—the PMA goes for $12,300/pair, while the PSA costs somewhat less per channel at $7300. I'd love to hear five PMAs in a surround system, which would carry a price tag of $30,750. And as Nagra's US service manager told me, having all those pyramids around might generate some new-age spiritual energy in addition to outstanding music.

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Jarod's picture

Hello Scott. I have question about inputs. What is the difference between balanced and unbalanced inputs?

Scott Wilkinson's picture
Unbalanced connections carry the audio signal on one conductor, while the second conductor is connected to ground; for example, with RCA connectors, the central pin carries the signal and the outer ring is connected to ground. By contrast, balanced connections carry the same audio signal on two conductors and a third conductor is connected to ground. The type of connector used for balanced cables is called XLR, which has three pins...two for the signal and one for ground.

The signal in one of the two conductors is 180 degrees out of phase with the other one, and its phase is flipped at the receiving end so the two signals are in phase. Why do this? Because any noise that pollutes the signal en route, say from stray electromagnetic fields, will be in phase on both conductors, so when the phase of one is flipped, any noise on that conductor will be exactly out of phase with the noise on the other conductor and thus be cancelled out. This effectively eliminates any induced noise in a balanced connection.

Jarod's picture

Thank you very much Scott for the great explanation! I now understand XLR inputs as well and there advantage.

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