how large this ratio can be made because of the parasitic elements of the windings, and it is
difficult to make an output transformer with more than a 25:1 ratio.
With the ZOTL technology, the impedance matching is determined by the effective turns
ratio of the RF converter transformers. Without the parasitics of an iron transformer core to affect
the audio, these RF transformers can have much higher effective ratios, and actually provide the
correct turns ratio to properly couple to the tube. This is more than twice the maximum turns
ratio that can be achieved with an output transformer.
The ZOTL technology results in very wide, linear frequency response along with an uncolored
and detailed presentation of the recording.
Amplifier Maintenance
The amplifier is self-biasing, and has no adjustments.
The amplifier operates the tubes in a manner that maximize tube life. The tubes are expected to
give 10 to 20 years of service based on several hours of use per day. See the section on Vacuum
Tube Replacement.
Fuses
The ZOTL10 has three fuses, two of the 5x20mm type 3.15A, in the AC power input assembly.
There is a 5A 5x20mm fuse on the audio board in the power supply in the lower section of the
amplifier enclosure.
Vacuum Tube Replacement
The amplifier comes with Genalex Gold Lion, which are high quality tubes currently in
production. Changing or “rolling” the tubes is at your own risk. If you choose to change the
tubes, be extremely careful to ensure the unit is off for at least 5 minutes to allow voltages to
dissipate.
Avoid touching the board, as high voltages may still be present even if the unit is
off.
Ensure the pins of the tubes are aligned with the tube socket. The amplifier is self-biasing, so
there are no adjustments necessary. Any damage caused by changing the tubes is not under
warranty.
Troubleshooting
If the amp is not turning on immediately after going into protection, turn it off and wait 30-45
minutes before trying again. Occasionally the circuit takes longer.
