Zesto Audio 2015 9 |
P a g e
Hookup, Settings and Adjustments
Before you start you will need:
RCA or XLR Interconnect cables to your system
Proper Care of your Leto Preamp
Very Important Read First
The simple rule to remember is to “turn on the preamp before turning on your power amp and turn off the power
amp before turning off the preamp.”
Not doing so may create a very loud noise that could damage your speakers or other equipment.
It is customary for vacuum tube equipment, when it is first turned on, while the unit is powering up, to have a brief initial
“hum” coming from the unit, not from the speakers.
It is very important that all of your audio equipment is
turned off
or unplugged from the main power before attempting to
install this unit.
Allow at least 30 minutes of warm up to get the best performance from the preamp.
Turn it on
Turn on the preamp using the ON/OFF switch located on the front left side. After a short time (about two minutes) the four
tubes should start glowing. The amber glow will be the only visible indication that the unit is turned on.
If they don’t, turn off the unit at the power switch and unplug the power cord. After waiting a few minutes unplug each
vacuum tube in turn (using the glove provided) and make sure that none of the pins are bent. If they are please contact
Zesto Audio for instructions.
Caution:
Tube electronics should not be turned ON, then OFF, then ON again quickly. This could blow a fuse or create a
hum. Once the unit is ON, it is safe to wait a minute before switching OFF. If you do get a hum, leave the unit off for 15
minutes.
Power
carefully plug in the AC power cable to the preamp first then to your main power.
Burn-in
Like all high end audio equipment, this Vacuum Tube Preamp can take
200 hours to
break in
. For circuit testing and
quality assurance, Zesto Audio ships all the Leto Preamps with at least
50 hours of factory burn-in.
Vacuum Tubes
Important!
First identify the two types of tubes as they are
NOT INTERCHANGEBLE
. Your input tubes are ECC83s
(12AX7) and your output tubes are ECC82 (12AU7). Please note that failure to follow this warning can cause considerable
damage.
Find the tube layout on page 8 in this manual in order to correctly plug in the right tube in the right socket. Using the glove
provided, unpack and carefully plug in the four vacuum tubes making sure they are firmly pushed in all the way in their
sockets. They can only go in one way.
Output
Using RCA or XLR interconnect cables; connect both the left and right outputs to your power amp.
Input
Using RCA or XLR interconnect cables; connect your sound sources to the inputs of the preamp.
Feet
Your unit is installed with four feet using #8-32 screws.
