MYTH: The protection circuit in Phase Linear amps is responsible for 80% of all failures and should be removed.

FACT: BS! The protection circuit protects against output stage failures by shutting down current drive to the pre-drivers in the event of short circuits or excessively low impedance loads. It works very well and should NOT be disabled. In fact, Bob Carver obtained a patent on the design (#3,727,148). Fuses alone are not good enough. Series I designs with germanium protection circuit transistors work best. Germaniums were replaced with silicon transistors in SeriesII designs strictly because of the cost and availability of germanium transistors. Other design changes accompanied the change to silicon protection circuit transistors.

MYTH: Bridge rectifiers have a high faiure rate and should be replaced with a higher current rectifer.

FACT: The stock 25A bridge rectifiers have a very low failure rate, even in amps such as the D-500 which has a very high turn on surge current. I don't recommend replacing them as a matter of course. I would wait until the stock part fails (be prepared to wait a long time!) at which time a higher rated rectifier may be substituted if so desired.

NOTE: Some bridge rectifiers could cause interference in nearby AM radios. A .22 uF /400V capacitor was installed across the AC terminals to prevent this. Another factory remedy was to install a Motorola MDA990-3 bridge which had lower switching noise.

MYTH: Never short the output of a Phase Linear amp or it will blow up.

FACT: More BS! The short circuit test is one of the most important reliability tests you can perform (the other is current sharing). At the factory, the goal was to "weed out" weak output transistors before the amp was shipped. Amps were vigorously and repeatedly shorted at full power in an effort to break them before being shipped.

MYTH: The VU meters used in Series I amps degrade the sound quality and should be disconnected.

FACT: The meters present a VERY high impedance to the output compared to the speaker load. The effect of connecting a meter to the output is immeasurable and highly debatable.

MYTH: It is possible to do distortion analysis by ear, therefore, distortion analyzers are unnecessary.

FACT: While some types of distortion are audible, a good distortion analyzer is absolutely necessary in testing Phase Linear , as well as other amplifiers. It is also essential that the output of the distortion analyzer be viewed on a scope. This can reveal high frequency oscillations riding on the output which are not be audible but can cause the amp to run warmer than normal and increase distortion percentage.

Distortion analyzers typically have very good built in voltmeters which is useful for measuring signal to noise ratio.

MYTH: The original Phase Linear 400 was designed by David Hafler and Bob Carver.

FACT: David Hafler had NO connection with Phase Linear and had nothing to do with the Phase Linear 400. David Hafler was involved with Dynaco which built the Stereo 400 which may be the origin of this myth.

MYTH: David Hafler and Bob Carver were partners in Phase Linear.

FACT: David Hafler was never partners with Bob Carver. Bob Carver's original partners were Steve Johnston (later of Hart Interface and Trace Engineering) and Jack Goodfellow, a successful local car dealer who provided financial backing.