Mike -
Couple of things.
1. The L-4 never was sold with 4-400s. I assume you mean 3-400Zs.
2. Electrically, yes, you can replace the 3-400s with 3-500Zs. The problem is that the '500s are a
little taller and won't fit in some of the chimneys Drake supplied. There really isn't any reason
to replace 'good' 3-400s with 3-500s as long as you stay within the original power specs. This is
about the limit of the power supply anyway. Yes, you can get close to today's legal limit, if you
really need that one quarter of an S-Unit increase.
The main 'significant' difference between the two is that the "B" moved the ALC level control from
the rear panel, and made it a 'push-pull' switch control to put the amplifier in standby. Pushing
the knob "IN" takes the amplifier off line without turning it off. With the L-4, you have to switch
the AC power off to bypass the amplifier. The 3-400/500Zs are 'instant on' tubes so not an
operating problem, but you could argue about turning the amp on and off multiple times.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
m coffey wrote:
Can anyone tell me the difference between the L4 and L4B ? Can one replace the 4-400s with
3-500s? Mike
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