Manley MAHI MONOBLOCK AMPLIFIER - Manual (Page 5)

GETTING STARTED
PREPARATION FOR INSTALLATION
Budget a suitable space in which to place the amplifiers and associated interconnect and mains power cables. This space
should be free of strong external magnetic and RF fields, and reasonably removed from strong loudspeaker-generated
acoustical fields. This space should also be free of excessive heat or dust and large enough to permit easy flow of cool air
to the top, bottom and sides of the amps. Do not connect the MAHI's to the AC mains until the other interconnections and
items outlined below have been completed.
Keep other associated equipment some distance away from the amplifiers. This will help keep airflow unrestricted, and cut
down interference from radiated magnetic hum fields that can eminate from certain power supplies. Notice that the output
tube’s glass envelopes are capable of reaching high temperatures, depending on operating circumstances. As with other
equipment of this sort, it is best to keep the MAHI out of reach of pets or children, or be careful to keep children and pets
away from the amplifier when in use.
People sometimes ask us why we don't supply a cage to protect children and pets from the scary exposed tubes. I always
answer that I grew up with a tube receiver and survived ok and a cage would look ugly. The only physical harm that came
to any of my family growing up from that tube receiver was once The Moving People dropped it on my mother's toe and
broke it. (Broke the toe, not the receiver. It worked fine for many years after that. And Mom's toe is fine too.) And so did
my little nephew who had one of my amps with scary exposed tubes from the time he was a wee lad. He not only survived
and is in college now, but when he was three years old he knew how to fire up the whole hifi even before his mom did. So
don't under estimate how smart your kids or pets are unless they are already prone to burning themselves on light bulbs. Or
just put these little amps up on a tall shelf out of the way. Actually I'd be more worried about little kids breaking my $3000
moving coil cartridge needle. Or The Cleaning People...
Before plugging in your interconnects, take a quick visual inspection of the tubes. Sometimes either through shipping or
unpacking things get jostled. Make sure all tubes are firmly in their sockets. You might also verify that none have turned
white inside. That indicates that air has leaked inside the tube (or the vacuum leaked out!). Though it is rare, a tube is
sometimes cracked or broken in shipping. It would need to be replaced before powering up the unit. Give us a holler if this
happens to you.
RCA INPUT
The MAHI has a single-ended input stage and therefore only accepts an unbalanced RCA input. Balanced XLR inputs are
not provided as that would necessitate adding more "stuff" such as IC's or transformers to the existing circuitry and for this
amplifier, we are going by the "less is more" philosophy. If you only have balanced XLR outputs on your preamplifier,
please check with its manufacturer as to how it would prefer to be hooked up into an unbalanced load. Some transistor
balancing circuitry wants to see Pin 3 of the XLR lifted while other circuitry, such as transformer-coupled line stages must
have their Pin 3 grounded. XLR female to RCA male adaptors are available if you need to make a conversion. The MAHI
does not invert polarity.
The MAHI is a sensitive amplifier. (It's soooooo sensitive.) With the Feedback switch set at MIN, less than 175 millivolts
RMS into the RCA jack will produce full output power. And there is no mute switch. So make your connections before
you power up the MAHI. Otherwise you'll get a big loud noise. That might scare your kids or pets. And keep them away
from your scary exposed-tube amplifier. Ah!
SPEAKER CONNECTIONS
Never operate the amplifier without a speaker load, or suddenly disconnect the speaker load
while the amplifier is producing a signal. This risks punch-through of the enamel insulation
covering the transformer’s internal magnet wire. Permanent damage to the output transformer
may result and for that, you will be made to pay dearly, dear.
So there you have it. The beautiful WBT binding posts fitted to the MAHI are for hooking up your speakers cables. RED
is positive and WHITE is negative. Get these to your speakers by way of nice speaker cabling terminated with bare wire,
bananas, or spades. The WBT's feature a nice slipping clutch action which will clamp down on your terminals without
spinning them. No need to tighten them like a gorilla or you might break something. Consider yourself well warned.
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