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Balanced Audio Technology VK-31SE Stereo Tube Preamplifier

Part II - On the Bench and Conclusions

January, 2004

Jason Victor Serinus

 

On the Bench (JEJ)

Tests were performed using the RCA unbalanced inputs and outputs.

With a 1 kHz sine wave, THD+N was a very low 0.007% and only two peaks could be seen, one at 2 kHz and one at 3 kHz. The noise floor is also very low.

IMD with 1 kHz and 1.5 kHz sine waves was very, very low.

IMD was also very low, using 5 kHz and 6 kHz input sine waves.

At 10 kHz, again, only two harmonics could be seen, with the second harmonic larger than the third. Compare this with the harmonics seen with many solid state products, and you will know why tubes are still a popular item.

Using 10 kHz and 11 kHz, IMD and THD were extremely low.

The measured frequency response is ± 2 dB 20 Hz - 20 kHz. The response might flatten out a bit with higher impedance inputs on power amplifiers. The input impedance of our sound card with the unbalanced connections is 12 kOhms.

Conclusions

As an equipment reviewer whose opinions affect consumer choices, I feel it essential to have as a reference system a set of components that excels at revealing small differences. Thus, my system includes such statement products as Nordost Valhalla cabling, cabling whose transmission speed, neturality, and transparency enable me to hear deeper into recorded music. I also feel impelled, within my limited financial means, to continually upgrade my components, using as my ultimate reference live unamplified sound in a variety of venues.

Over the past six months, I have had the opportunity to compare four different preamps: three tube and one solid state. The differences I can hear between these products have increased as my system has improved. This paradoxically leaves me in a situation where I hear things that other listeners may either not hear or not find of concern.

The BAT VK-31SE is an excellent preamp, one whose build, bass slam, and midrange fullness will please many readers. Paired with the right components, especially those that will benefit from its strengths, it will prove an excellent addition to one’s system.



- Jason Victor Serinus -

Associated Equipment:

Digital Front End:
Sony 707ES transport modified by Alexander Peychev
Audio Alchemy DDS-Pro transport
Theta Gen. 5A single-ended DAC (to be replaced with the Gen. VIII);
Perpetual Technologies P-1A with Modwright modified Monolithic Power Supply and Revelation Audio umbilical power cable

Amplification:
Bruce Moore 100W dual mono tube power amp with Electro-Harmonix KT-88s and Siemens Cca tubes
Monarchy Audio 100W SE-100 deluxe solid state monoblocks

Preamp:
Bruce Moore Companion III tube preamp with Electro-Harmonix gold pin 6922s and Jan Philips 12AU7 equivalents;
Reflection Audio Om-1 Quantum battery-powered preamp in non-battery mode

Loudspeakers:
Talon Khorus X speakers (with latest modifications that make its response even across the spectrum and greatly improve the bass)

Cables:
Digital: Nordost Valhalla interconnects and digital interconnects
Nordost Valhalla bi-wired speaker cable
Powercables: Elrod EPS-1, 2, and 3 and EPS Signature-2 on main chain plus Harmonic Tech, Nordost, and AudioPrism Super Natural S2 elsewhere

Accessories:
PS Audio P600 Power Plant power synthesizer with MultiWave II
PS Audio Ultimate Outlet; PS Audio Power Ports
Michael Green Deluxe Ultrarack, Basic Racks, room treatment, and Audiopoints
Black Diamond Racing Cones
Inner tube, maple cutting boards, bags of sand
Shakti stones on Amp and Monolithic/P-1a
Bedini Quadra Beam Ultraclarifier
Audioprism Stoplight and Blacklight, Marigo Disc
Gryphon Exorcist
Sheffield/XLO degmagnetiser and break-in disc and Ayre demagnetizing disc

 

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