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Messages - ylo

#1
I too bought a Lab Series L5 earlier than 1979.  As I recall, it was '77.  I will try to confirm this and get back to this forum.

I have compared the L5 to my 1971 Fender Twin Reverb in terms of sound and circuits. It sounds remarkably like a Twin Reverb in side by side comparison, but provides a little more note separation and clarity. The Normal channel of the L5 is a clone of the Fender Twin Reverb in many ways.  The tone stack has the same corner points, but is designed to work at lower impedance to match opamps instead of tubes, so the R and C values differ.  I have rigged the reverb tank to run off of the Normal channel, and in this configuration, the amp excels at doing the surf music & twang thing.

The Limiter control seems to emulate the tendency of Fender BF and early SF amps to hit the wall when cranked past 4 or 5.  The distortion circuitry in the L5, which comes into play if you crank the volume but reduce the master volume, seems to be an attempt to emulate the 12AX7 / 7025 preamp distortion that you can get if you dime some of the old Fender, but of course it sounds a bit harsh and "solid state" compared to the real thing.

By the way, you can get a reasonable bluesy sound by setting the controls so that the amp just begins to distort when the limiter engages, although this takes quite a bit of tweaking.

The Reverb channel on the L5 is another story.  I'm not sure what the designers were going for here.  With the Mid control at "0" and the Multifilter at "0", the treble does not provide very much brightness.  You have to add Multifilter to get the amp into brighter territory.  The sound with the Multifilter turned up is interesting and different, but not particularly my cup of tea for most songs.  I think the Multifilter is either an attempt to make a solid body guitar sound "woody" like an acoustic or archtop, or else it is an attempt to emulate the standing wave nodes and sound of a 4 x 12 cabinet as in Marshall.  It would be interesting to get some info from the original designers about the design philosophy behind the Reverb channel.

I know a guy that distributed Lab Series amps in the late 70s, and will contact him and ask him whether he can provide some more insight on these amps.