Manley MAHI MONOBLOCK AMPLIFIER - Manual (Page 6)

MOVING RIGHT ALONG...
NOW THAT YOU HAVE ALL YOUR CABLES PLUGGED IN, you may now connect the IEC power cord to the
MAHI and to an energized power outlet. (Unless you live in California and are in the middle of a Rolling Greyout®™.)
Fire up all your upstream devices first: sources, preamplifier, and such and allow them all to finish their turn-on cycles
so your MAHI will not be amplifying any of their waking-up noises. My nephew was able to master that turn-on sequence
thing when he was a wee lad of only 3 years old. I swear.
Once your front end components are stabilized, you may now switch ON your MAHI's. The mains power switch is
located on the back of the chassis right at the IEC power inlet. You shouldn't need to turn the Mahi around or get
yourself behind it. You should be able to "feel" the rocker switch located next to the AC power cord. (We stuck the
power switch way back there to keep the noisy mains furthest away from the input circuitry.) Flip the switch away from
the power cord to turn on the Mahi or towards the power cord to turn off the unit. The MANLEY MAHI badge will light
up. Sometimes you might see a flash out of the little input tube's heater as it turns on. That's normal so don't worry about
it. I told you, stop worrying about it!
STOP WORRYING ABOUT EVERYTHING AND JUST GET LISTENING! Once audio is first heard from the
Mahi's, please notice that it takes about 45 minutes of warm-up time for the system to reach thermal equilibrium. During
this warm up time, go walk your dog, make dinner, or play some lite pop music. Some Elvis "Blue Hawaii" would be a
fun choice. Or even Don Ho. Well, what you listen to is up to you.
POWER DOWN (What? So soon?) (No silly, when you're done, unless you just wanna practice!) As a rule, power up
your amplifiers last, power down them first so they do not amplify any stray noises which could occur upstream from
source components powering up or down. Additionally, it is best to cut power to the Mahi when not in use rather then
leaving the power on indefinitely. This will enhance tube and system life. The tubes should last thousands of hours under
normal conditions. Especially if you check your BIAS every once in awhile. Keep reading to learn more about tubes and
then on page 8 you can learn about biasing your Mahi's.
TRIODE vs. UL vs. TETRODE: The MAHI output tubes can be switched to run in TRIODE mode or Ultra-Linear
mode. Number one thing though, we really recommend that you TURN OFF the amplifier and count to five BEFORE you
throw this switch. Triode is when the screen grids are hooked up to the plates of the EL84's. Triode mode is known to be
very sweet and seductive sounding, but alas, it is a more inefficient way to run the output tubes. You only get about half
the power in Triode as you would in Tetrode. Ultra-Linear, often called "partial triode," is when the screen grids are
hooked up to a special taps on the primaries of the output transformer. These UL taps are located somewhere special
between the center tap and the outside anode taps. Tetrode (or Pentode) operation is when the screen grids are hooked up
directly to the center tap B+ of the output transformer. We don't give you that choice here but we want to tell you about
it to help you understand more about UL. The sound of Tetrode mode is a little rougher and less refined than triode, but
way more powerful, and sometimes, you really need more power. What is great about Ultra-Linear is you get the best of
both worlds and how much of each world we choose to allow into the final result is dependent on where we choose to
put the UL taps when we are designing the output transformer. The closer we choose to put the UL taps to the outside
windings, the more triode-like the UL mode will be. The closer we put them to the center tap, the more powerful tetrode-
like they will be. For this little amplifier's UL taps, we found a place where we felt the best balance of the two extremes
would be so you still get lots more power, and it still is sweet, and it also has that driving and boogie-ing character that
makes your toe tap. And again, remember, it is best if you TURN OFF the amplifier, count to five, throw the Triode-UL
switch, and then power back on the amplifier if you want to compare between triode and UL modes. Most people find a
preference and stick to it. You are free to do as you choose. It's a free country.
VARIABLE FEEDBACK: Some global negative feedback is employed in the MAHI. A bit of the output signal is taken
off the final speaker outputs and is routed back to the input stage. The entire circuit, including the output transformer and
some loudspeaker back-EMF, is thus included in the feedback loop, all 3dB's (MIN), 6dB's (STD), or 10dB's (MAX) of
it, which ain't that much actually compared to some amplifiers we could mention. You can choose how much negative
feedback is applied with the Variable Feedback switch. Negative Feedback alters the slew rate or "speed" of the amplifier.
Feel free to experiment with this switch any time, even while playing tunes, even for different music. Use your ears and
pick whatever setting you like, whenever you like. Knock yourself out.
TUBES RULE! While we could lauch into a whole lecture about the technical advantages of vacuum tubes, such as high
headroom, big Joules, graceful overload characteristics and all this stuff, I'd rather get down to what's really important:
Music is an emotional thing. There's no "right" or "wrong." Whatever gets your toe tapping is what is "right" for you. We
enjoy working with vacuum tubes because we find we can get them to translate this emotional connection from the tunes,
through hunks of steel, through the air to your ear where it reaches the enjoyment central station of the brain and then
gives you those goosebumps. Try to measure THAT! Nah, don't. What we'd like you to really do is to enjoy years of
fabulous music through your Manley MAHI's.
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