Nagra BPS Bipolar Transistor Phono Stage, MM/MC, Mint and Complete - Battery or DC Powered
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Nagra BPS Bipolar Transistor Phono Stage, MM/MC, Mint and Complete - Battery or DC Powered
479 South Broad Street
Glen Rock NJ 07452
Don't be fooled by its compact size, Nagra has been making exemplary audio components for decades - all in Switzerland- all in about 1/2 the weight and space as others without sacrificing a bit.
This BPS is no exception. When it comes to a phono preamp, keeping the noise level down is one of the biggest challenges since the signal coming from the cartridge is so low.
Nagra has solved this issue by allowing several different power configurations with the best being internal batteries. That's right the BPS can run on internal batteries for 100 hours. You can also run it from a standard 9 Volt power supply (not included but we can facilitate one), and finally utilizing the power channel from a Nagra MPS or similar.
Available loadings for MC are 100, 150, 220, 330, 470, and 1000.
This BPS is in mint condition with every bit as it come from the factory including the loading modules.
More from Nagra:
The appearance alone of the Nagra BPS phono preamplifier expresses the philosophy behind the development of the unit.
Compact: The BPS measures only 110 x 27 x 160 mm (4¼ x 9∕16 x 6¼ inches) and can easily be integrated into any set-up, as close to the tonearm as possible. It is a concentration of state of-the-art technology.
Simple: Easy connections and a single switch on the front face to enjoy the very best of vinyl records.
Solid, reliable: A typically Nagra construction and finish. Finely brushed anodized aluminium, Swiss build precision.
Once again, timeless Nagra electronic design.
A NEW PINNACLE FOR VINYL DISCS
A very compact link aimed at the most exclusive installations, the BPS phono preamplifier opens the door to quality vinyl listening of the highest order. Never before has the technology linked to this timeless support achieved such transparency, so naturally in perfectly silent operation. Designed in the same manner and by the same engineering teams as for the renowned recorders, the Nagra BPS preamplifier is the result of engineering pushed to the limits in every respect. From the conception of the electronic circuits to the final test procedures, everything is done to assure the same goal: a lively reproduction as close as possible to the true original sound.
IN THE SAME LINE AS THE PRESTIGIOUS PREDECESSORS
The Nagra BPS benefits from successive developments of the previous Nagra preamplifiers, the PL-P and more recently the VPS – both tube based units. The Nagra BPS uses the same principle circuit design, but with transistor technology giving extremely low power consumption, allowing a miniaturization and rationalization of the device. Thanks to this approach, the Nagra BPS is positioned in a competitive place amongst the other preamplifiers of the Nagra range. Associated to the Nagra PL-L line preamplifier and one of the company’s power amplifiers, the Nagra BPS serves as a system entry offering unequalled neutral and transparent qualities. End-to-end clarity in the pure Nagra tradition.
ELEGANCE OF THE CONCEPTION, INTEGRITY OF BEHAVIOUR
The preamplification of a signal coming from a turntable is a delicate operation. It requires managing an extremely low level and particularly vulnerable audio signal. This is a problem that Nagra engineers are confronted with on a regular basis with professional recorders, of which the microphone inputs are also extremely sensitive. The Nagra BPS preamplifier incorporates a group of proven solutions that give it the highest possible integrity in signal management. Sources of potential disturbance have been taken into consideration from the outset. The schematics have thus been drawn using in-house methods, concentrating on the essential elements and avoiding any superfluous components. An elegant approach benefitting the final behaviour of the unit.
THE HIGHEST POSSIBLE PERFORMANCE
Thanks to the minute consumption of the circuits, the Nagra BPS was able to be fitted with a power supply based on a simple battery. An ideal situation in terms of operational silence.
The unit escapes from the traditional mains power supply problems: residual background noise, electromagnetic interference, extra weight and bulky size. The entire electronics of the Nagra BPS are on a single high quality board, with the shortest possible tracks to carry the signals. The connections are all soldered directly on to the circuit. The electronic component placement has been particularly studied to avoid interactive disturbances. All these cumulative measures assure reaching the highest possible performance and reliability.
INPUT TRANSFORMERS “MADE BY NAGRA”
The inputs of the BPS preamplifier are equipped with very special transformers, with a magnetic glass-metal core. As with the recorders, it is one of the key pieces of the unit, that the company designs and winds entirely in their own laboratories. Nagra is one of the rare manufacturers in the audio world to have the particular know-how, which they have perfected for decades: one of the “secrets” leading to the inherent Nagra quality. Thanks to these transformers, which are mounted inside μ-metal magnetic shielding, the Nagra BPS preamplifier has excellent characteristics in terms of linearity, saturation level and low frequency management.
A TOTALLY PROGRAMMABLE UNIT
The market offers a wide range of cartridges designed for turntables, and of differing technologies: Moving coil (MC) and moving magnet (MM). These cartridges have widely varying characteristics. This diversity is no problem for the Nagra BPS preamplifier, as the unit is totally programmable by the user to obtain a perfect correlation between the load of the cartridge and the circuit. A set of jumpers and loading modules are provided, used depending on the different cartridge characteristics. The inputs can also be switched to floating, that is to say disconnected from the earth, thus avoiding all earth loop problems generating parasitic noise.
Nagra is a brand of portable audio recorders produced from 1951 in Switzerland. Beginning in 1997 a range of high-end equipment aimed at the audiophile community was introduced, and Nagra expanded the company’s product lines into new markets.
Originally a product of the Kudelski Group, Nagra recorders are now developed, produced and sold by independently-owned company Audio Technology Switzerland S.A., based in Romanel-sur-Lausanne.
The machines were initially designed by Polish inventor Stefan Kudelski, and his company won numerous technical awards for their precision and reliability. Nagra means "[it] will record" in Polish, Kudelski's mother language.
Nagra-brand tape recorders were the de facto standard sound recording systems for motion picture and (non-video) single-camera television production from the 1960s until the 1990s
Input connections: RCA-Cinch (gold-plated), Output connections: RCA-Cinch (gold-plated)
Accurate to the recording
9/10 = Excellent. Perfect physical condition, gently used.. See our detailed rating description here.
Working perfectly and tested in our lab and listening room.
Exactly as pictured and described above.
Original Manufacturers Packing
20 Hz (+1dB) at 30 kHz (0dB) RIAA conform
> 77 dB (ASA A)
Typically 60 dB
Input circuit load:
47 kΩ without load module installed
6 modules supplied (100, 150, 220, 330, 470 Ω and 1kΩ)
Transformer gain (MC input):
Ratio 1:3.54 (+11 dB) RIAA stage gain 53 dB
64 dB, switchable to 49 dB with internal jumpers
2V Power consumption:
1 x battery 9V type 6LR61 (PP3)
12,6 W (in 1.6W stand-by mode)
Power supply External:
94-132 V or 188-264V / 44 to 66 Hz
Estimated battery life:
Approx. 100 hours
4-¼" x 9∕16" x 6-¼"
Kimber Kable - RCA Interconnects - Better
Kimber Kable - Phono Interconnects - Better
We start with a visual inspection of all internal components to make sure that there are no signs of heat stress or damage. Capacitors are checked for telltale signs of predictive failure including bulging, shrunken wrappers, or physical leakage. We also inspect the PCB’s for discoloration from resistors or transistors that may have been running hot. On vintage units we often spot check select capacitors for value and ESR.
When we first power on a preamplifier we connect its RCA output to a Sencore PA81 Power Analyzer which simulates real world loading conditions and gives us an oscilloscope interface. The first order of business is checking that the volume control works smoothly throughout its entire range with acceptable channel balance. This is accomplished by feeding a 1KHz sine wave into one of the preamp’s line level inputs while monitoring the preamp’s output on an oscilloscope. We then switch to a 1KHz square wave to test the tone controls, loudness function, and filters where applicable. During this step we are watching for equal alteration of the test signal by both channels. This also helps us identify dirty controls that will need treatment. Once the basic line stage functions are verified, we test each input individually. This is especially important for devices that use relays to select their sources. If the preamp is equipped with a phono stage we test that as well. We use an inverse RIAA filter which allows us to feed a reference test signal into the phono input with the proper RIAA equalization and level. A square wave or sine sweep is used to verify that the device’s phono stage is faithfully reproducing the RIAA curve. If the preamp under test has balanced inputs and/or outputs these are tested as well.
We finish up our bench testing with a listening test with our bench amplifier and reference speakers. During this test we check for hum or hiss that may not have shown up in earlier testing. We also check that all of the tone controls and filters perform as expected. If the preamplifier has remote control functions these are also tested. Preamps with tube circuits or complicated power supply topologies are connected at our long term test rig for extended stress testing under real world conditions.