D.W. FEARN
VT-1 &
VT-2 Microphone Preamplifers
11
History of the VT-1 and VT-2
Vacuum Tube Microphone Preamplifiers
ONE D
AY IN 1991 I was going through some old masters in a closet at home and
came acr
oss a reel from 1968. It was one of the first studio recordings I ever made.
I pulled t
he tape box off the shelf and thought about those days. Although I suspect-
ed t
hat the recording might be a bit crude, I remembered that the music was pretty
good, so I made a cassette to listen to in t
he car.
I kept forgetting to put the cassette in my pocket for a few days, but finally I remem-
bered to take it. That old recording brought back memories of my first studio — and
how primitive a setup it was. But listening to that tape was a revelation; some of the
sounds w
er
e really nice. The vocals were full and warm but still punched through.
A
coustic guitars had a depth I don’t often hear in current recordings. And the sax
solo — w
ow! It ripped through with a grossly distorted but beautifully powerful sound.
That r
ecording was done on a 4-track Scully 280 and mixed to a 2-track Scully. My
prize micr
ophone was a Neumann U-87 and that’s what was probably on the featured
instrument or voice on each track. Nothing too unusual about that.
I couldn’t afford the Electrodyne board of my dreams back then. In fact, I built the
“mixer” myself. It consisted of half a dozen RCA tube microphone preamplifiers that
I salvaged from the junk pile of the radio station where I worked, an equal number of
old Da
v
en rotary faders, and key switches that “panned” the output to left, center, or
right.
It w
as the
tube preamps t
hat made that recording sound so good. There was no EQ,
no r
everb, but maybe just a touch of compression on some sounds, from an old broad-
cast type (tube) limiter.
These pr
eamps were 1940s vintage. They used octal metal tubes with a shielded grid cap, a
cylindrical output transf
ormer the size of a coffee can, and a huge power supply on a sepa-
rate chassis. They were a lot of trouble — the tubes were microphonic and the output was
often noisy. In addition to the hums and hisses, occasionally a take would be ruined by crack-
les and bangs from the tubes. I couldn’t wait to get rid of the things.
And so I did, not long after
. I got a beautiful console with IC op amps, linear faders, real pan-
pots, echo sends and returns, and EQ on every input. No more noisy tubes for me.
But now, 25 years later, I got to thinking about the sound of those tubes. Hit them with a bit
of ex
cessive level and the sound became real fat. Hit them with just the right level and they
sounded w
arm and intimate.
Could that sound be duplicated today? I dug out my old RCA Receiving Tube Manual and
se
veral other old reference books and reviewed the vacuum tube theory I hadn’t thought
about for years. A quick check in the supplier’s catalogs confirmed that tubes were still easy
to obtain.
(31 paginas)
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