Summit TD-100 Operating Manual

Summit Audio Model TD-100
Instrument Preamp and Tube Direct Box

Operation Manual

Summit Audio, Inc.
P.O. Box 223306
Carmel, CA 93922
[phone]
email: [e-mail]

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Introduction

The TD-100 is a single channel direct box and instrument
preamp featuring a hybrid signal path utilizing a solid state
output device and a 12AX7A/ECC83 vacuum tube. This
unique combination of of solid state and vacuum tube tech­nology gives the TD-100 the benefits of both worlds: the high
reliability and long life of solid state and the warm overtones
associated with vacuum tubes. Other great features such as
continuously variable input impedance, polarity switching, and
a headphone output make the TD-100 a great sounding tool
for the studio or the stage. Enjoy!

DANGER!

HIGH VOLTAGE

IMPORTANT: Check

the back panel to make
sure the TD-100 is
configured for the volt­age used in your coun­try. This is done at the
factory ONLY.

Features

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Ease of Operation

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Headphone Output
Variable Input Impedance
Direct Output for easy parallel connections
Balanced Outputs
Hand Crafted in the U.S.A.

Carefully unpack the TD-100 and it’s power cord. Save the
carton and packing material for possible future use. Before
powering up the unit, read this manual and observe the cau­tions for

HIGH VOLTAGE

.

Model TD-100 Tube Direct Box

2

Front Panel

Front Panel

GRO

UND

POLARITY

SIGNAL

LIFT

+-

DIRECT OUT

INPUT

1M

10K 2M

LOADING

SIGNAL

0

OUTPUT GAIN

Ground Lift Switch

This two-position switch removes the third prong of the
power cable from the circuit. Lifting the ground can some­times reduce the hum caused by a ground loop in your audio
system.

Polarity Switch

This switch changes the polarity of the outgoing signal.

Direct Instrument Output

This jack mirrors the instrument input. Plug your instrument
into the input and run a line from this ouput to the input on
your amplifier. This output is not affected by the Loading
control.

DRIVE

TUBE DIRECT

INSTRUM

24

TD-100

ENT PRE-AM

ON OFF

P

Instrument Input

Input for your bass, guitar, keyboard or other instrument.
The maximum input level is +24dB.

Model TD-100 Tube Direct Box

3

Front Panel

Loading Control

This knob controls the loading or impedance for the instru­ment input. The impedance can be set from 10K ohms to
2M ohms.

You can set this control to match the TD-100 to the imped­ance of your instrument or as a kind of tone control. In prac­tical use you’ll set this control to get the sound you like best.

Signal LED

This green LED lights to indicate a proper level at the input.

Drive LED

This amber LED lights to indicate clipping on the input.

Output Gain Control

This control varies the output gain. The XLR output can be
varied from -20dB to +4dB. The 1/4” TRS output can be
varied from 0dB to +24dB.

(0dB input level)

Power

This switch toggles AC power on and off.

Important - Please Read!

The TD-100 contains a vacuum tube which

generates heat.

Do not block the cooling holes on the top of the

TD-100 and always allow adequate ventilation when

mounting the unit in a rack enclosure.

4

Summit Audio, Inc.

Rear Panel

Rear Panel

FUSE

CLASS A -TUBE INSTRUMENT PRE-AMP
MODEL TD-100 20 WATTS MAX

115V 50/60 HZ

SUMMIT AUDIO INC. CARMEL, CA USA

PHONES

A.C. Receptacle

The TD-100 is factory wired for either 100, 115 or 230
Volts AC. Before connecting AC power make sure the
TD-100 is wired for the voltage used in your country.

Headphone Output

Use the TD-100 as a practice amp by inserting your head­phones here. Use the Output Gain control and the instru­ment’s volume control to control the volume.

1/4” TRS Line Level Output

This is a balanced/unbalanced 1/4” high level output
designed to interface with your recording device, compressor
or EQ without adding a preamplifier. Simply plug in a mono
phone plug to use this output unbalanced.

BALANCED

OUTPUTS

LINE

PIN2+

MIC

XLR Mic Level Output

This is a balanced low level output used for injecting the TD­100 into another preamplifier. This is most often used in a
live performance setting. Pin 2 is positive (+).

Model TD-100 Tube Direct Box

5

Basic Operation

Basic Operation

Important: For proper

operation of the
TD-100 (or any vacuum
tube device for that
matter), allow the unit to
warm up with power on
for 15 minutes before
use.

Important:

the cooling holes and
allow adequate
ventilation.

Do not block

Just Plug-in & Go

1.

Plug your instrument into the front panel input jack.

2.

Connect either the rear panel balanced Mic or Line output to
the input of your mixer or recorder. (An unbalanced cable can

be used with the Line Level output.)

3.

Adjust the Output Gain for an optimal signal level.

4.

Adjust the front panel Impedance control to match for the
best sound.

5.

Start playing!

6

Summit Audio, Inc.

Applications

Live Sound

A direct box or “DI” (direct input) is used to take a high
impedance instrument signal and transform it into a
balanced, low impedance output. In the example below, the
Direct Output feeds the Bass Amp and the low impedance,
balanced microphone output is sent to the mixing console.

Direct Box Connection

Applications

Model TD-100 Tube Direct Box

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Applications

Using the TD-100 as an Instrument Preamp

You can use the TD-100 to go directly to your recording
device for an ultra-quiet sound. The output is already ampli­fied so there’s no need to re-route through your mixer. The
line level output of the TD-100 is ideal for interfacing with any
other effects you wish to use.

8

Summit Audio, Inc.

Balanced

To Recorder Input

Using the TD-100 and TLA-50 together

For a great bass or guitar channel, try using the Summit
Audio TD-100 instrument preamp and tube direct box in
conjunction with the TLA-50.

Plug your instrument into the front panel of the TD-100 and
run an XLR or 1/4" cable from the output of the TD-100 to
the input of the TLA-50. Use the 1/4” output of the TD-100
into the TLA-50 to go directly from the TLA-50 to your
recording device, or use the XLR output of the TD-100 into
the TLA-50 and patch the XLR output of the TLA-50 into a
microphone preamp, then into your recording device.

Applications

(such as the Summit TLA-50)

Compressor

FUSE

CLASS A -TUBE LEVELER
MODEL TLA-50

100V 50/60 HZ

115V 50/60 HZ

SUMMIT AUDIO INC.

CARMEL, CA USA

OUTPUTS

+4 BAL. -10 UNBAL.

INSERT

SIDE

CHAIN

20
WATTS
MAX

PUSH

INPUT

LINK

+4 BAL. -10 UNBAL.

Balanced

To Recorder Input

Model TD-100 Tube Direct Box

Balanced

9

Circuit Explanation

INSTRUMENT

INPUT

IMPEDANCE

Circuit Explanation

12AX7A

AMPLIFIER

DIFFERENTIAL

OUTPUT

DIRECT

OUTPUT

GAIN

Tip

The Instrument Input to the TD-100 is directly connected to
the Direct Output. The Impedance control sets the input
impedance of the first stage input. The Impedance control
can be used to match the impedance of the instrument and
to provide subtle tonal coloration.

The TD-100 features a vacuum tube amplifier driving an elec­tronically balanced output stage. All the signal amplification in
the audio path takes place in the tube circuit. The balanced
output drivers provide a low output impedance for driving
cables and 600

Ω

loads.

Signal

Present

Peak
Hold

10

Summit Audio, Inc.

Electrical
Connections

Input

Unbalanced 1/4” jack

Sleeve - - Ground
Tip - - - - (+) Signal

Electrical Connections

Output

Balanced 1/4” jack Balanced 3-pin XLR

Sleeve - - Ground Pin 1 - - Ground
Tip - - - - (+) Signal Pin 2 - - (+) Signal
Ring - - - -(-) Signal Pin 3 - - (-) Signal

Model TD-100 Tube Direct Box

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Specifications

Specifications

Circuit Topology

High-voltage Class A

Gain

Switched 6dB steps, maximum gain +24dBu (at 1/4” TRS
output)

Maximum Output Level (Class A)

+24 dBu. The outputs are electronically balanced or
unbalanced. XLR type (pin 2 hot), 1/4” balanced TRS
(Neutrik)

Input

Input impedance is variable from 10K
Maximum input level is +24dBu unbalanced.

Ω to 2M Ω .

Noise 20kHz unweighted

-121 dBu minimum gain position

Distortion THD, IMD

0.07% at +10 dBu

Frequency Response

-/+0.01dB, 10Hz to 100kHz

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Summit Audio, Inc.

Power

Internal AC Supply
20 watts
115 volts
50 or 60 Hz
Fuse size is .5 amp, slo-blo for 100/115 V
Fuse size is .25 amp, slo-blo at 230 V

Dimensions

W:

8.5”, H: 1.75”, D: 8.5”

standard one-space rack shelf.)

(Two units fit side by side on a

Weight

Specifications

7 pounds (3.15 kg)

Model TD-100 Tube Direct Box

13

Summit Audio, Inc.
P.O. Box 223306
Carmel, CA 93922
web page: www.summitaudio.com
email: [e-mail]

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TD-100 Op Rev. A