Bass Gear Issue 7 : Page 341.6dB, compared to the “all controls at noon” response of +/-4.6dB ( Fig. E ). For both measurements, Ultra Hi was switched on, and Ultra Lo was off. For the optimally flat response in this passband, set the tone controls as illustrated in Fig. F . To see the effect of the Ultra Hi and Ultra Lo switches, we compared the full-range, all controls at noon, setting with both switches engaged, compared to both switches disengaged ( Fig. G ). The Ultra Hi is capable of adding 15dB of treble boost centered around 6 kHz. However, the natural low-pass filtering of the tone circuit keeps this high frequency boost behaving more like a bell curve than a high shelf, which keeps hiss under control. The Bass sweep is illustrated in Fig. H . The Mid sweep is broken down into two charts, where positions 1, 3 and 5 on the midrange dial are shown in Fig. I , midrange sweeps 2 and 4 on the midrange dial are shown in Fig. J and the Treble sweep is shown in Fig. K . Output Power On the bench, the SVT-7Pro tested well. At 8 ohms, we measured 457 watts continuous, with bursts reaching 483 watts. At 4 ohms, we measured 763 watts continuous, with burst reaching 914 watts. All tests at 5% THD+N, filtered 20Hz-20kHz. The amplifier consistently output just shy of 48dB gain and a linear response in view of varying level ( Fig. L ). The amplifier burst response is shown in Fig. M . In this test, we deliberately push the amp into limiting, and this result shows the signal gracefully entering and exiting the limiter. Conclusion To challenge the Hughes-Cox Law, I looked back to our 1974 Ampeg SVT, reviewed in issue #4. If our math is correct, our test SVT7-pro sees an 83% reduction in weight, a 92% reduction in tube count, and a 185% increase in output power, compared to our ’74 SVT. The tests suggest that this amp performs like you would expect an SVT to perform. Yep, the SVT is alive and trending well. Now go forth and make music, no back brace required. Fig. K Fig. L Fig. M  %&& !$%# Publication List Using a screen reader? Click Here |
