Warranty Explanation
Recently we had to change our warranty for the LNPA 150 Monoblock Amplifiers.
Over the past few years we have encountered some tube pre-amps that can cause severe problems for the LNPA 150's as well as other solid-state amplifiers. During bench testing, we have seen measurements that indicate some tube pre-amps are destabilizing and acting as wide band RF receivers and transmitters. This means that the frequencies and the amplitudes of the frequencies transmitted from the pre-amps are so high that the standard RC low pass filters generally used in solid state amplifiers are overwhelmed. The result can cause internal destabilization in the circuitry of the LNPA 150 (and other solid state amps) resulting in failure. These very high frequencies must never be transmitted into audio equipment. They must be properly filtered out.
R.E. Designs had two choices to make to address this problem. We could design new input filters but this would require "specially adapted" pre-amps to drive the input of the LNPA 150, or we could qualify our warranty. For this reason we decided on our second choice: Qualify the warranty. R.E. Designs reached this decision on the basis that it would not effect the vast majority of R. E. Designs customers. R.E. Designs is not the only manufacturer who has concerns regarding the problems caused by certain tube pre-amps. Other manufacturers have privately voiced their concern also. R.E. Designs, however, may be the first to make this matter public.