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Groove
Tubes
Groove Tubes has always been
associated with making outstanding sounding products
over the years. The company started out back in
the late 70's and gained their reputation by manufacturing
tube guitar amplifiers that were known for their
amazing tone. Groove Tubes has always had a loyal
following and once any of their products are used,
chances are you'll become a fan too.
Groove Tubes and Aspen Pittman
have recently redesigned and reintroduced their
microphone line with M Audio as their new distributor.
One of the newest features of these condenser microphones
is that they contain a disk resonator. This resonator
extends the frequency response of the microphone
up to 20kHz, whereas most microphones have a steep
drop-off around this frequency. For purposes of
the review, these microphones were tested out in
a few professional and home-based studios. The microphones
worked extremely well in both environments, with
very little variation in their sonic performance.
GT-33
The Groove Tubes GT-33
is referred to as mid-diaphragm condenser microphone.
The GT-33 employs the use of a hand assembled
.75-inch gold plated diaphragm with Class A FET
electronics. FET stands for Field Effect Transistor
and is a type of transistor that is used to amplify
a signal. This is commonly used in place of tubes
since they are said to exhibit fairly similar
characteristics to tube based amplifiers and are
cheaper to manufacture and implement. The GT-33
comes with a Cardioid capsule, but you can purchase
a separate Super-Cardioid or Omni Capsule.
The GT-33 is an extremely versatile
microphone that can be used to capture a number
of instruments with great clarity. I tested this
mic on a number of sources like acoustic guitar,
banjo, drum overheads, tablas, percussion, bass
guitar cabs, guitar cabs.
I used the GT-33’s on
the Larrivee acoustic guitar with a TL Audio tube
pre-amp and the results were outstanding. The GT-33
has replaced my old stand-by for recording acoustic
guitars. The GT-33 also had great results with drum-overheads.
The 33’s gave great depth and detail to the
drums while still remaining natural. The exact same
held true with percussion. I wasn’t totally
pleased using the 33 on a series of guitar cabs
and bass cabs, but using small to medium sized condenser
microphones is typically not the best choice for
recording these sources.
Overall, I think that the GT-33
is one of the best sounding small/mid sized diaphragm
microphones you can purchase, especially if you
need a matched pair of microphones for recording
any acoustic instruments.
GT-44
The GT-44 is a mid-sized diaphragm
condenser microphone that uses a miniature pentode
tube, where as most tube microphones are using a
triod tube. The GT-44 implements a .75 inch hand
assembled evaporated gold diaphragm and has a –15dB
pad and a low frequency roll off switch (75Hz).
Just like the GT-33, you can purchase separate capsules
that allow you to change the pattern to Omni or
Supercardioid. The GT-44 comes with its own power
supply (a requirement for a tube mic), a really
nice proprietary multi-pin XLR cable to connect
the 44 to the power supply and a shock mount.
A nice feature on all of the
GT microphones is that they are all transformer
coupled. It is commonplace these days to find a
number of transformerless condenser mics. The reason
for using a non-transformer-based design is that
is usually lowers the self-noise of the microphone
and gives a “cleaner” signal. The disadvantage
to transformerless microphones is that some people
describe them as being “harsh” and “brittle”.
GT has somehow managed to get the best of the both
worlds. The GT-44 is has a notably low noise floor
for a mic that incorporates a tube and transformer
in its design. When used properly can give a certain
color to your recording that some engineers prefer
.
I tested the GT-44 with the
same instruments as I tested on the GT-33, yet got
slightly different results. On the acoustic guitar
the GT-44 sounded like it was missing some of the
midrange detail that the GT-33 had. I also thought
the GT-33 sounded better than the 44 when recording
banjo, yet I preferred the GT-44 for drum-overheads
and percussion. The GT-44 has a slightly more “compressed” sound
than the GT-33, which I usually prefer for overheads.
The 44 also gave the whole drum kit great “presence” and “depth” and
the same held true with percussion. I also tried
the 44 on an old beat up upright piano. I ended
up tracking the piano using the 44 and an Avalon
737 and the results were amazing. Every single nuance
of the piano came through in sparkling detail. The
44 also gave good results on a clean electric guitar.
I used the 44 with an old Fender Twin amp and a
Les Paul. While this is a common guitar and amp
combination the results with the 44 were really
good and we actually ended up using this sound on
a number of tracks.
If you are looking for a well-rounded,
well-manufactured tube mic that won’t break
the bank, yet will give you great performance, you
should take a serious look at the GT44. I would
recommend the GT44 for anyone who is recording modern
pop, rock, to even blaring hard rock. The slightly
compressed and minimally colored sound will add
to the overall effect of the recording.
GT-57
The GT-57 is a multi-pattern
large diaphragm condenser microphone that uses a
rather large 1.10” evaporated-gold diaphragm
and FET electronics that is transformer coupled.
The GT-57 features 3 different polar patterns: Cardioid,
Omni, and Bi-directional (figure 8). The 57 also
has a –10dB pad, for those singers who are
just always too loud and a 75Hz roll off filter;
which would come in handy if your singer has a problem
kicking the mic stand.
The GT-57 is assembled solidly
with a rather heavy build, and is housed in a black
case. It is so heavy, in fact, that it takes some
serious tightening of the mic-clip to get the microphone
to stay stationary. The 57 has a tendency to tip
over cheap microphone stands, so be careful!
I tried the GT-57 on the all-same
the same instruments that are listed above, yet
tossed in a few more sources including, male vocals,
a small choir and different array of percussion.
The 57 gave good results on the acoustic guitar
and banjo, but I preferred the sound the GT-33 for
these instruments. The 57 was a touch muddy in the
low-mids, but this is common when using large diaphragm
condensers. However, some recording engineers prefer
this sound. I did get amazing results with the male
vocalist and the choir. The 57 beat of a number
of other microphones that are more expensive and
generally more revered. A keynote on the 57 is that
the proximity effect sounds amazing on male vocalists.
The choir was recorded in Omni mode in a medium
sized room and the 57 I felt as though it captured
the exact sound that was occurring in the room.
I also tried the 57 on a floor tom, since I’ve
never been happy with the standard dynamic mics
that are usually used with toms. This was done with
the pad engaged through a UA 610 pre-amp. The 57
captured the exact nuances of the tom and sounded
HUGE. It was almost as though a cannon was exploding.
The drummer was also happy with the sound of his
toms, which is a rare occasion. The 57 also sounded
great on percussion. I ended up using the 57 to
record a few cabasa and tambourine tracks. Once
again the 57 captured the instruments exactly. If
you are looking for a large diaphragm condenser
microphone that is built to last, sounds great and
is inexpensive you should take a serious look at
the GT57.
GT-67
The GT-67 uses the same capsule
as the GT-57, but amplifies signal with the help
of a miniature Pentode instead of a Field Effect
Transistor. Like all of the GT microphones, the
67 is transformer coupled. The 67 has a number of
selectable polar patterns which makes it an extremely
versatile microphone. On the back of the 67 you
will find Cardioid, Super-Cardioid, Bi-directional
(figure 8) and Omni. Switching polar patterns also
changes the frequency response of the mic, and this
gives a number of different timbral options while
recording. You will also find a (–10dB) pad
switch and a 75Hz roll off filter on the front of
the mic.
The 67 comes in a “flip-top” box
with a rather heavy power supply, a nice shockmount
and a multi-pin XLR cable that connects to the power
supply. Tube mics require their own power supply
since tubes due top the need for more than 48 volts
to power the plate. Condenser mics also need power
that is dedicated to power the diaphragm.
I mainly used the 67 to record
male vocals and clean to moderately distorted guitar
amps. On male vocals, I fell in love with this mic
and ended up using it a number of times. With this
vocalist, the 67 actually beat out a number of other
well-known microphones. This mic maintains amazing
detail throughout its frequency response yet had
enough highs to cut through dense mixes, without
sounding harsh or muddy in the low-mids as is common
in many large diaphragm tube mics. I also got great
results with the 67 on a Vox AC30. It gave a lot
more detail than the dynamic mics we tried and also
captured small amounts of the room we recording
in. Capturing the room, in this case, gave the guitar
a more natural sound than you normally get by placing
a microphone 2” away from the speaker. The
67 also had great detail while recording a mono
drum overhead and a drum room.
The 67 is a great microphone
for male vocals and I would not hesitate to use
it with any female vocalists. When matched with
a good pre-amp the 67 shines. Returning this microphone
to M Audio was a rather painful experience. I am
planning on picking one up for my next recording
session!
Overview
All of the GT microphones are
manufactured with great quality using high quality
electronic components, something you don’t
always find in microphones these days. More importantly
all of the GT microphones sound great and I would
recommend them to anyone who is looking to purchase
a microphone for a home studio or even larger studios
looking to outfit their “closet”. One
thing that caught me off guard is that all the GT
microphones come in plastic flip-top boxes, while
some of them have the mics placed in a plywood case.
I assume this was done to keep the costs down. Barring
the funky case, GT has manufactured some amazing
sounding mics.
To find out more about
mics in general and GT's line specifically, check
out Record
Now. M-Audio
and Aspen Pittman have teamed up to offer this
educational resource, stuffed full of useful info
for choosing and using microphones.
Have questions regarding this
review...email Greg
Ripes
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GT
Microphone Overview