Tried and true: The Manley 500 and 250 Watt Monoblocks are our most powerful push-pull production-models. Both the circuit design and the selected componentry have been refined over years and years of development. Reliability that you can depend upon combined with musical accuracy and emotional authority is what these amplifiers promise- and deliver. They are able to switch operation modes allowing the listener to choose between the sonically seductive qualities of triode and the more powerful Ultra-Linear configuration. We use big, beefy reservoir capacitors in the high voltage supplies giving plenty of instant energy for dynamic performance of transient peaks and bass impact and weight which often exceeds that of rival solid-state amplifiers. We run high voltages on the plates of the output tubes but operate them at lower current which will result in their longer life. Although each output tube has its own bias-adjust, We carefully fit each amplifier with computer-batched tubes for optimum performance. The bias adjustment pots and measuring points are conveniently located behind the oval front panel insert.
To avoid a heavy power drain when the cold amplifier is first switched on, we conceived a "Soft-Start" mode which also functions as an "Ever-Warm" position allowing the amplifiers to be always warmed up for pleasurable listening. Each amplifier only consumes 30 watts of power in Ever-Warm mode. A blinking green LED reminds the user that the amplifier is in warm-up mode because as all the power supplies are at half-voltage, the amplifier will still operate at half power when the Ever-Warm mode is engaged, so the user should use the MUTE switch when in this mode.
The front-panel mute switch and angled-back chassis make it easier to hook up the interconnects, speaker cables, and IEC power cord.
In our own in-house magnetics department, our R&D team completely redesigned all of our output transformers in 1998 with the goal to reclaim that luscious rich mid-range of our vintage designs. In 2013 we reworked the output transformer to operate the output stage in Ultra-Linear mode which is a great sounding balance between the detail of triode and the brawn of Tetrode. We also specifically set out to achieve a deeper bottom register at higher power with lower distortion. Hours and hours of listening tests, measurements, and fine-tuning brought an exciting and stunning result to our ears. We hope you will agree.
- ALL-TUBE monoblock design 10 x KT90EH Electro-Harmonix Russian output tubes
- High current double 12BH7EH driver stage
- 12AT7EH large plate Electro-Harmonix Russian input tube
- BALANCED & UNBALANCED inputs
- MUTE switch
- TRIODE / Ultra-Linear switching
- SOFT-START/ EVER-WARM standby mode
- MANLEY Precision output transformer
- Factory set for 5 Ohms nominal
- Front panel bias measurement and adjust (hiding under the black insert)
- Large filter / reservoir capacitors 3800uF x 2
- Angled rear of chassis provides for easy connections
- WBT binding posts
- Input sensitivity: 1V
- Gain: 32dB tetrode; 30dB in triode
- Input Impedance RCA: 116 kOhm @ 1KHz
- Input Impedance XLR: 270 kOhm @ 1KHz; 20 kOhms @ 20KHz; 38 kOhm @ 20Hz
- Noise Floor: Tetrode: -67dB; Triode -65dB typical
- S/N Ratio: -80 dB
- Dynamic Range: 96dB
- FLAT frequency response: 10 Hz - 30 KHz continuous
- Power Consumption: 30 Watts in "EVER-WARM"
- Full power (tetrode): 500W
- Full power (triode): 275W
- Factory set for 100V, 120V or 220-240VAC operation for original destination country's mains voltage.
- Operating Mains Voltage changeable with power transformer re-wiring and fuse value change.
- Mains Voltage Frequency:
- Dims: W=19", D=13", H=9"
- Shipping weight: 82 lbs. each
FREQUENTLY ASKED QUESTIONS
What tubes should I get for my Manley 250's?
If you are retubing, we would suggest the stock original tubes. For the output tubes, we use the EL34EH (Russian Electro-Harmonix), and have found these to be quite good. We sell them at $14/ea in quantities of 20 (two matched sets of ten). At times we are also using the JJ Slovakian EL34's supplied to us by our good buddy Aspen Pittman at GT. I have also heard good things about the Svetlana EL34's but have not evaluated them extensively because factory supply from the Svetlana St. Petersburg factory is unreliable. It's tough to evaluate the lifespan of a tube until it dies so we stick with what we know works and sounds good. The 6414 driver tube is a bit of an oddball, with GE and Raytheon being the ones you will probably find (that's what we have here- $15/ea). The 12AT7 input tube is very common, and we use the Ei version here ($15) which most audiophiles are fond of. I am personally a little afraid of untested "new old stock" tubes at high prices. There may be a reason they have been kicking around for 30 years. And also as we run each and every tube we put in all of our gear through a battery of noise, operation, gain, and matching tests and purposefully select every tube specifically for best performance in that specific product and circuit, we think we are putting the very best tubes in Manley gear that we can possibly put in there.
Help! A tube blew!
Read this: Changing Cathode Resistors in Manley Amps
Also shows Cathode & Screen Resistor locations and PCB layout and tells you what to do if a tube blows. And even how to fix it without soldering!