Recording - March 2018 - 37

500TDI Tube Direct Box

The newest piece in the LaChapell line is the similarly-styled 500TDI, a 500 Series
tube interface for the direct injection of instruments-most typically bass, but also
electric guitar, some acoustic/electric guitars, and even synths
and electric pianos.
Visually it shares a layout with the preamp,
although its input and output knobs are
black. Instead of a row of toggle switches, you get a single toggle switch that
engages a highpass filter to get rid of
low rumble. There's a pair of 1/4" Hi-Z
jacks; the top one is the input, and the
bottom is a Thru to send signal on to
an amp or pedals. Note that the Thru
can act as a parallel low-impedance
input if needed.

A Tube DI, not a line level pre

The big thing to be aware of is that
this is a tube DI unit, not a line-level
box. It can be used to direct-inject
instruments into your mix, but like a
true DI, it also loves being used in front
of a standard microphone preamp...
like the 583s mk2! It's a very clean design with
zero ICs in the audio path. It has a transformerless input
and a transformer-balanced out, and makes use of a 12DW7 (ECC832) tube.
It offers 24 dB of gain, THD+N 0.10%-25% (@+2 dBV), an 8 Hz-28 kHz frequency
response, an EIN of -100 dBu, and an input impedance of 1.5MΩ-high enough for
most instruments aside from the most finicky piezo pickups on acoustic instruments.

Sounds like

The best word that comes to mind with the 500TDI is solid. It yields a strong clear
capture of the source, but it's not clinical, boring or anemic. Like its mic pre cousin,
you have full control of the tube saturation, so it can move from clean to smooth and
gently sweet at the twist of a dial.
If you want channel drive, this is where you would want to place the 500TDI
before another preamp. If you know you will be re-amping the signal, it works best
on its own. One mistake I often encounter with many instrument tracks recorded
through the inputs on many microphone preamps is that it's too easy to slam the
signal as hot as possible into the DAW. This can cause issues if you decide to
re-amp, whether in the box through plug-ins, or worse yet, back out into an amp and
external pedals. With the 500TDI on its own, even signals pushed to the max from
a bass or guitar are never overbaked or too loud.
I used the 500TDI with my Rickenbacker 4003 bass, a 1970s Rhodes MKII electric
piano, and a Fender Telecaster. In each case I was very pleased with the results, both
in its own or even before clean preamps like a Millennia Media HV3D. If you want
darn near set-it-and-forget-it, great-sounding direct instrument tracks that require little
fixing or diddling around, then it's the 500TDI all the way. LaChapell should consider
making a standalone DI box version, as this could make a great live rig box.
It's great to hear new devices and hear new sounds from the tube wizards at
LaChapell Audio; both of these boxes are seriously impressive!

PRICE: 583S mk2, $945; 500TDI, $700
MORE FROM: LaChapell Audio/Digital Audio Labs,
www.digitalaudio.com
RECORDING March 2018

http://www.digitalaudio.com http://www.adkmic.com

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