L-8500 OTL/OCL Tube Preamplifier

In an OTL/OCL preamplifier, there is no coupling device between the preamplifier and the power amplifier , that is, the preamplifier’s final output tubes are directly connected to the power amplifier. Normally, an Output Capacitor or Output Transformer for separating AC music signal from the DC operating potential; if this is not done, the latter will destroy the power amplifier or loud speakers.

But these two types of coupling devices are effectively obstacles to transmission that add their own character (color), increase distortion, and consume small signals according to physical efficiency theory. In addition, they limit signal dynamics.

Because of all these adverse effects, OTL/OCL has been considered the best solution for amplifiers in order to maintain signal purity.

* Removing these two coupling devices from the signal path, gives the best results.

* No coloration is added to the musical signal.

* Extremely detailed expression, natural harmonics and subtle musical decay are achieved.

* There is the lowest distortion possible due to the absence of coupling parts.

* The widest musical dynamics are attained.

* Some circuit experts might worry about DC potential in the music signal, but there is no need to worry. Allnic uses a “floating power supply circuit” which prevents the creation of any DC potential in the first place.

*The OTL/OCL circuit is basically SEPP, “Single Ended Push Pull”, so we need a “cancellation circuit”, which adjusts the balance of signal between the upper and lower power output tubes’ input grids.

Allnic uses the most sophisticated “Active Balanced Positive and Negative Feedback Circuit”, in which a 6AN8 pentode perfectly controls all the circuit’s entire operation with extremely low distortion and the greatest speed.