PSE took three top
DI’s into the studio and put them through their paces. Here’s
what we learned.
Left to right: The A Designs
Reddi, Manley Labs’ All Tube Direct Interface, and Demeter
Labs’ VTDB-2B.
Direct boxes are often
the unsung heroes of a recording session, allowing a high impedance
source such as an electric bass, keyboard, or guitar to be played
directly into the recording chain without the use of a microphone.
Over the years, a number of manufacturers have developed tube DI's,
offering a variation from the traditional solid state DI in respect
to tone color.
We tested three of the leading tube DI's to learn just what these systems
offer and where they excel when it comes to recording direct. The
test subjects include DI's made by Manley Labs, Demeter Labs, and A
Designs. They were tested first on electric bass, and then on an acoustic
guitar with a pickup system.
Nacnud Sound owner and
session bassist Rick Duncan laying down a bass part through
the test DI's.
We chose Nacnud Sound (a DI'sc Makers Studio Partner) located about
45 minutes south of Sacramento, CA for our session. Not only is studio
owner Rick Duncan a fine engineer – with more than 20 years
experience working with artists such as Tesla, Tower of Power, and
Bill Champlin of the band Chicago – he’s also a talented
bassist who volunteered to play for the first test session.
The set up
After arriving at the studio and DI'scussing our approach, Rick pulled
out his 1962 Fender Jazz Bass reissue and we got to work. Two local
engineers, Spencer Johnson and Mike Tompkins, joined us to provide
additional ears for the evaluations.
I asked Rick what he normally uses on electric bass on a session and
he pointed to a stack of Countryman FET Type 85s, a ubiquitous studio
and live sound DI known for its reliability and smooth performance.
We agreed to do a test track using the solid state Countryman as our
baseline sound. Rick had prepared a 60-second drum loop to play along
to, so we got ready to lay down the test track.
Inside the control room
at Nacnud Sound.
Nacnud has a D&R Orion
32-input console, but it’s used primarily for monitoring from
his Pro Tools HD rig. He has a variety of high-end preamps, and we
selected a Martinsound MSS-10 to patch the DI into. From there, we
went directly into his ProTools HD system.
Monitoring was done through a pair of Genelec 1030 A speakers. We
recorded the bass part through the Countryman to use as a reference
to a “regular” session at Nacnud and proceeded from there.
Throughout the bass test, all pots on the Jazz Bass were set to full
on.
Bass Test 1. Manley All Tube
Direct Interface
First up was the Manley tube DI. It’s a one-rack unit using
a 12AX7 tube with 1⁄4” input jack on the front panel and
XLR out on the back. Controls are well laid out and easy to access.
The build quality is excellent, the unit feels solid and is easy to
set up and use. The manual is informative, written in a conversational
tone, and helps to understand the features and options of the unit
nicely.
Manley All Tube DI during
the test session.
A unique feature of this
product is the five-position low frequency roll off selector, designed
to reduce unwanted resonances in the lower range. It also allows you
to shape the tonal response of the All Tube DI to suit your recording
goal. For bass, we used the recommended settings: “Bass Full,”
which provides the flattest response, and the toggle switch set to
“Unity.” The manual includes frequency response charts
showing exactly what the EQ curves are doing when engaged.
The tone was similar to the track recording using the Countryman.
The mids and highs were clear, though the low end didn’t seem
to be quite as open. Rick said the sound seemed a little compressed
and asked us to give him more bass in the cue mix. We double-checked
the Manley’s controls to make sure we were in the recommended
setting for bass (we were) and laid down the track one more time with
identical results.
We then used the EQ control and tried out the various settings. As
advertised, each one gave a different EQ curve which affected the
sound of the Jazz Bass by moving the low frequency roll off up the
spectrum, a feature that we didn’t find helpful for bass.
2. Demeter VTDB-2B
The Demeter VTDB-2B looks like a typical direct box, housed in a rugged
case, suitable for work on stage or in the studio. Controls are extremely
simple and well labeled. Like the Manley, it offers switchable output
level (Unity or Boost) and also features the 12AX7 tube. Build quality
was similarly solid. We set the output at Unity, set levels to match
that of the first two units, and were ready to begin testing.
Demeter VTDB-2B during
test session.
Everyone commented immediately
that the instrument sounded more open and fatter than the Manley,
and richer than the baseline Countryman DI. With the Demeter in the
loop, the Jazz Bass exhibited a richness and presence we had not heard
before. Overall tonal response was very smooth, especially in the
lower register of the Jazz Bass which was full and round. I actually
asked Rick if he also had a subwoofer behind the console, to which
he laughed and replied, “No!”
A Designs Reddi during
test session.
3. A Designs Reddi
The first thing we noticed about the Reddi occurred before we even
set eyes on it. The shipping box is large and it is heavy in comparison
to the other units. Once unveiled, the 10-pound Reddi looks like a
red bar of steel (one you would not want to drop on your toe!). The
fire engine red DI features a purple pilot light that emits an eerie
glow into a dimly lit studio.
As with the other two
DI's, the build quality is exceptional, with all front panel controls
well marked and easy to access. Unlike the two previous units, the
Reddi has a potentiometer, which affords up to 16 dB of gain should
it be needed. Another difference is that it runs on a 6NI-P tube,
rather than the 12AX7s found in the other units.
After setting levels we got down to recording. The first impression
of the Reddi was that the bass sound was tight and focused with plenty
of punch. The Reddi was clean and natural and had the warmth typical
of tube circuits. In fact, all four engineers felt that it was very
similar in sound to the VTDB-2B.
Bass test analysis
After we were done recording the final tests, we set out to compare
the three DI's in back-to-back listens. The Countryman and the Manley
sounded good, with the expected additional tonal warmth in the Manley
track. However, there was a marked difference when either of the first
two (Countryman or Manley) was compared to the Demeter or the Reddi.
The latter were bigger, fatter, and rounder sounding tracks. The similarity
in tone and response between the Reddi and the Demeter was verified,
however, a slight edge had to be given to the Demeter, as the lowest
range of the Jazz Bass sounded a bit more open and rich.
Tube DI's for Acoustic Guitar
Mike Tompkins (seated)
and Spencer Johnson in the control room tracking the bass DI
tests at Nacnud Sound.
The Manley’s switchable
low frequency roll off feature got us talking about testing it on
an instrument other than the bass. A few nights later, Mike and Spencer
ran all three tube DI's through their paces as local guitarist Peter
Gothold played his Larrivee LV 03R acoustic guitar with a built-in
B band A5 pickup system. The location was Mike’s apartment using
his Pro Tools LE rig with and M-box 2 interface.
We began with a baseline recording, plugging right into the M-box
2. All tone controls on the B-band were set flat. Then, using each
of the tube DI's, we DI'scovered how each would perform on acoustic
guitar. Here’s the report.
1. Manley All Tube DI
Although we didn’t find the low frequency roll off EQ useful
when recording the Jazz Bass, on the acoustic guitar with built-in
pickup, it was ideal. The roll off points are 12Hz, 42 Hz, 100 Hz
and 250 Hz, which meant that as Peter played the guitar, we flipped
through the EQ settings and found the one that gave us the best results.
We didn’t hear much difference on the 12 and 42 Hz roll off
settings (“Bass Medium” and “Guitar/Synth”
respectively), but the last two settings (Guitar Medium and Guitar
Bright) worked nicely to eliminate the Larrivee’s bass boominess.
This resulted in a transparent, open sound with loads of natural warmth.
We settled on Guitar Medium as the best fit for the Larrivee’s
sound.
2. Demeter VTDB-2B
Right away, we found that we didn’t have enough level coming
into Pro Tools, so we engaged the “Boost” switch. That
gave us a bit too much, and we had to turn down the input to avoid
DI'stortion. The guitar’s tone was noticeably warmer than plugging
it straight into the M-box, but the mid frequencies of this instrument
seemed to be pushed out front a bit too much for our liking.
That mid boost reduced the apparent level of the highs and lows, which
none of us liked. We recorded flat, but it should be noted that with
judicious use of EQ, a usable tonal balance would be fairly easy to
achieve.
3. A Designs Reddi
Once we set levels, the Reddi had a smooth overall sound from high
to low. With both of the other DI's, when Peter played very aggressively,
we had some overloading, especially when he played with a muted, heavily
percussive attack. It was apparent that the Reddi handled these high
transients much better than the other two DI's. In fact, there was
almost no overload when he played at the same intensity, demonstrating
the headroom of this DI. The overall tone quality was very good, sounding
natural and strikingly similar to the instrument’s own unamplified
sound we heard before we powered up the studio.
And the Winner Is…
Overall, the Manley was the most versatile DI in the acoustic guitar
test. Having the option to shape the guitar’s sound, and reduce
the boominess was a big plus. The Reddi was nice, too, in that its
overall response was smooth and natural, though it lacks the option
to shape the low frequencies. Depending on the instrument and player,
some EQ would likely be needed to tailor the low end.
Although the Demeter’s tube improved the guitar’s sound
noticeably over the straight-to-M box, it also boosted the mids in
a way that jumped out a bit too much for our liking, (that could be
tweaked in practice with some EQ). With regard to overall headroom,
the Reddi was the clear winner, at least in the acoustic guitar test.
For bass, all four engineers liked both the Demeter and the Reddi,
with a very slight edge going to the Demeter for its tonal response
in the very lowest register of the bass. In terms of flexibility,
the Demeter was the smallest of the three, and could readily be tossed
in a gig bag or shoulder bag to bring to a remote. The hefty Reddi
would be best suited to staying at home in your studio, awaiting your
next session. The flexibility of the Manley All Tube DI, which made
it the winner in the acoustic guitar test, wasn’t a factor on
the Jazz Bass test, making it the least favored of the three tube
DI's for bass.
It should be noted that each bass has its own tonal characteristics,
and different models are likely to get slightly different results
than our tests. Be sure to demo any exotic audio gear in your own
studio whenever possible before making a purchase. Almost all dealers
offer a trial period as part of the purchase. Hearing the gear in
your studio is always the best way to know if it will work for you.
What’s the Price Tag?
As might be expected, custom-designed, made in the USA, hand-built
tube direct boxes are going to carry a higher price than a mass produced,
solid state box found at a local store. Correspondingly, expect the
sound quality and longevity to be much better for these high-end DI's.
The manufacturer’s list prices are:
Demeter VTDB-2B – $599
Manley All Tube DI – $575
A Designs Reddi – $795
Special thanks to
Peter Montessi at A Designs, James Demeter at Demeter Labs, and EveAnna
Manley at Manley Labs for providing the equipment for the test sessions.
