Manley Neo-Classic SE/PP 300B Monoblock
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Manley Neo Classic SE PP Front Manley Neo Classic SE PP Right Side 

Product Details

Beautiful simple, the 300B directly heated triode was one of the very first 3-element piece tubes, comprising just filament, input grid and anode output. Brought to reliable perfection by Western Electric USA and later by Standard Telephones UK as the 4300B, the 300B was very much intended and widely used for telephony amplification. But audio enthusiasts of old knew a good thing when they heard it and the great love affair between the 300B and music began... and dwindled many years later as the American Western Electric 300B was taken out of production in the late 80s making the genuine ones extremely valuable and very highly prized as collectors' pieces. Asian audiophiles had a passion for these units and with the resultant revival of SINGLE ENDED topology, the call for the 300B to be put back into production was just too tempting for Chinese & Russian factories to resist. In turn the re-start of US manufacturing of genuine Western Electric originals has further expanded the selection. Basic thermionic simplicity. Directly-heated triodes. It's a holy grail for some people…

Reviews:   PF Magazine by Dr Harvey "Gizmo" Rosenberg
  A 300B inspired "Spiritual Woody" by Dr. Harvey "Gizmo" Rosenberg
  Enthusiastic testimonials from proud owners

With its decidedly and deliberately 'retro' physical proportions (deep front-to-back dimensions with a narrow side-to-side width) this layout closely follows design concepts from a bygone era. Keep the power supply as far as possible from hum and noise susceptible octal input tubes. The output tubes themselves require careful distancing from the mains transformer and, of course, require pure DC on their filaments. Again, in a nod to past times, the use of vacuum tube rectification with gentle voltage rise-time. To bring overall performance up to modern times, Manley use two rectifiers, enabling the use of substantial filter/reservoir capacitors. Over 1300 microfarads in the B+ rail. (4 or 8 back in the 1930s!)

When other manufacturers started selling single-ended amps with 5 to 9 watts of power, Manley's team clearly and objectively grasped the concept. Superb mid range, delicate detail, inherent simplicity. The bad news was that there were very few speakers efficient enough to help form a dynamically viable system. To make matters worse for afficionados, either these single-ended amps cost more than their houses or they had laugh-out-loud specs. As the triode fans increased, more efficient speakers became available and several fanatics began to dismiss push-pull as a bad thing - something to be avoided at all costs. Manley's take on this was that push-pull, when correctly done, with true phase-balanced transformers, quality parts throughout and well designed circuitry, is a superb technique. Single-ended topology sounds great but only when it's done right, mostly because users expect flat frequency response and low distortion from an amplifier. Manley knew they could achieve this in a properly conceived single-ended design and rose to the challenge, designing circuitry (understood to be unique in the industry) which could be switched "on the fly" From 18 watts in parallel SINGLE-ENDED to 36 watts in PUSH-PULL.

The Output transformer (again hand-wound in their own factory) is a complex design employing inordinately high primary inductance to compensate for the mandatory magnetic "gap" required for the uni-direction current and voltage flow of the single-ended output stage. Another factor in the single ended triode saga (currently enjoying a wide spread popularity) is demand for little (or sometimes zero) negative feedback. Manley's team believe in a judicious or sensible amount of feedback to refine and maximize performance. The Neo-Classic SE/PP300B gives you the choice in precision switched 1 dB steps to go from ZERO dB's to 10 dB's of negative feedback. Even with zero negative feedback, this amplifier is cleaner and flatter than any single-ended unit in its class.


Vacuum Tubes:
2 x 300B (Output)
1 x 6SN7 (Driver)
1 x 6SL7 (Input)
2 x 5U4 (Rectifier)
Output Power @ 1Khz with 5 dB FeedBack in SINGLE-ENDED: 11 Watts @ 3% THD
Output Power @ 1Khz with 5 dB FeedBack in
PUSH-PULL: 24 Watts @ 1.5% THD.
Frequency Response with 5 dB FB in
SINGLE-ENDED: 15 Hz - 15 Khz +/- 0.5 dB (measured at 5 watts)
Frequency Response with 5 dB FB in
PUSH-PULL: 10 Hz - 20 Khz +/- 0.5 dB
GAIN: 20db w/10dB FB setting; 30dB w/0dB FB setting in SE mode
Input Sensitivity with 5db FB SINGLE ENDED: 700mV
Input Sensitivity with 5db FB PUSH-PULL: 450mV
S/N Ratio:
SINGLE ENDED: 83.5dB Ref. 1W; 2.83v//8 ohms,20KHz BW; 5dB FB.
PUSH-PULL: 85.4dB Ref. 1W; 2.83v//8 ohms; 20KHz BW; 5dB FB.
Dynamic Range:
SINGLE ENDED: 94dB Ref. 3% THD; 20KHz BW; 5dB FB.
PUSH-PULL: 99.5dB Ref. 1.5% THD; 20KHz BW; 5dB FB.
Input Impedance: 100Kohm, direct coupled.
Load Impedance (switchable):
4 to 12 Ohms appropriate for 4 & 8 ohm speakers
12 to 20 Ohms appropriate for 16 ohm speakers
Power Consumption: 240 Watts max.
Mains Fuse:
100, 110, 120V use 3 A (Slo-Blo)
220, 240 V use 1.5 A (Slo-Blo)
B+ Fuse: 400 mA, (Slo-Blo) Ceramic Body.
Lamp: 1/4" X 1 1/4" "fuse- lamp" 8 volt, 0.3 amp
W= 8.5, D= 23, H= 9 inches, Including projecting controls and parts
Shipping Weight: 41lbs/18.60kgs each

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