Allnic L5000 DHT User guide

ALLNIC AUDIO

L-5000 DHT LINE STAGE PREAMPLIFIER

OWNER’S MANUAL

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ALLNIC AUDIO
L-5000 DHT LINE STAGE PREAMPLIFIER

Thank you for purchasing this Allnic Audio L-5000 DHT Line Stage
Preamplifier. We are certain your trust in Allnic Audio and Hammertone
Audio, as well as your appreciation for the sound of this high-quality device,
will be rewarded by its excellent operation for years to come.

Please read this entire manual before you connect the L-5000 DHT Line
Stage Preamplifier to the other components of your system and the wall
outlet.

252 Magic Drive, Kelowna, British Columbia, Canada V1V 1N2
Direct Telephone: [phone]; Fax: [phone]
email: [email protected]
Website: www.hammertoneaudio.com

** Information and specifications for the Allnic Audio product

described in this manual are subject to change without notice.

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TABLE OF CONTENTS:

___________________________________________________________________

INTRODUCING THE L-5000 DHT LINE STAGE PREAMPLIFIER 4
___________________________________________________________________

WHAT’S IN THE BOX? 6
___________________________________________________________________

SAFETY 6
___________________________________________________________________

CLEANING
Chassis
Connectors 6
___________________________________________________________________

INITIAL SET-UP
Location, Location, Location
Power Connection
Inputs
Outputs
Phase Switch
Remote Control 6
___________________________________________________________________

INITIAL POWER ON 8
___________________________________________________________________

OPERATION 8
___________________________________________________________________

TUBES 9
___________________________________________________________________

SPECIFICATIONS 9
___________________________________________________________________

WARRANTY 10
___________________________________________________________________

FIGURES 11

Please read about SAFETY before you attempt to use the L-5000 DHT Line
Stage Preamplifier - we care about our customers and the equipment, and
we want you to enjoy this product for a long time!

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INTRODUCING THE L-5000 DHT PREAMPLIFIER

Allnic Audio and the Direct Heated Triode Breakthrough

In the early years of the last century, the directly heated
triode was invented independently, and almost
simultaneously, in the USA and Austria. This simple device,
an anode, cathode and a grid in a vacuum contained in a
glass bottle, transformed the world. With all the
applications in which it has been employed, and with all the
changes in electronic design for audio reproduction that
have occurred since its invention, it is remarkable that over
one hundred years later, the very first triode, the simplest
vacuum tube audio signal amplifier, despite the
imperfections ascribed to it, remains a favourite audio
amplification device of many devoted music lovers
worldwide.

Debate, on both subjective and empirical bases, about the
quality of the directly heated triode’s sound reproduction
potential continues even today. One of the interesting
aspects of these debates is the degree to which they ignore
analysis of common, fundamental assumptions based on
decades of circuit and mechanical design experimentation
and compromise, about the use of these devices. Indeed,
because of the difficulties in application of directly heated
triodes in audio circuits, many issues arising out of circuit
design problems related to them have evolved into
assumptions about the audio characteristics of the valves
themselves.

Allnic’s Mr. Kang Su Park has spent a lifetime studying and
designing circuits and transformers for application of direct
heated triodes for audio reproduction. By questioning basic
assumptions about the valves and re-examining the original
and many historical variations of circuit designs for them,
and experimenting constantly in a framework of rigorous
application of theory, Mr. Park’s work has resulted in some
remarkable audio power amplification devices. With the
300B, for example, his creations produce significantly more
power than is expected (without shortening valve life
because the power increase is not achieved by increased
bias), in conjunction with exceptionally low distortion and
wide bandwidth.

Now, Mr. Park has successfully combined elements of what
he has learned and invented over decades to the
development and production of a pure, direct heated
triode (DHT) based preamplifier. The main breakthrough,
which came after several years of work applying all he
knows, was the design of a circuit, valve and transformer

combination the measured results of which astounded
him. The purity of its square wave reproduction – as
perfect as anything he had ever seen from a DHT valve
amplification circuit – had him questioning what he was
seeing! Of course, he tested and re-tested, replicated and
recorded these results many times before assuring
himself that there was no mistake.

With such an unprecedented outcome for the circuit
design, Mr. Park could not be satisfied merely with
placing a DHT stage after one or two prior stages of
amplification using indirectly heated triodes. This
approach is used in a number of commercially available
preamplifiers using DHT’s, but it is a compromise. It does
not result in PURE DHT amplification; it necessarily
introduces the characteristics of indirectly heated triode
sound into the circuit, so the output DHT’s are only
amplifying a signal already affected by the indirectly
heated triodes in the prior stage or stages.
Mr. Park, though, has created a preamplifier that uses
DHT’s at each amplification stage. In his design, the
output stage DHT’s are not merely amplifying the signal
from previous, indirectly heated triode stages. The L-5000
DHT preamplifier is pure DHT - from input to output.

Of course, Mr. Park is not the only builder who has
accomplished this, but to our knowledge no other pure
DHT preamplifiers have been commercially available.
There are serious and significant reasons why such
preamplifiers could not be acceptable in the marketplace.
First among them has been the enormous problem of
microphonics. One of the many special elements of Mr.
Park’s design is reduction of microphonic influence on the

DHT’s. Where others have sometimes accepted the effects of
this problem because even with it they prefer the incredible
realism of the pure DHT approach, Mr.Park has succeeded in

creating a circuit and mechanical design that reduces the

DHTs’ susceptibility to microphonic influence to insignificance.

Like the Allnic L-3000, which is an indirectly heated triode
preamplifier, the L-5000 has a noise floor that is
effectively absent.

The Allnic L-5000 DHT preamplifier is THE WORLD’S FIRST
COMMERCIALLY PRODUCED, PURE DHT PREAMPLIFIER.

Currently, the L-5000 DHT’s large output tubes are very
rare items, produced many decades ago. Allnic has been
able to secure a limited number of these valves, enough
to produce an also limited number of the L-5000 DHT
preamplifier. ONLY A LIMITED NUMBER OF UNITS OF THIS
DESIGN WILL BE MADE. This allows for valve stock to be

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retained for replacements, should that ever become
necessary, something that is unlikely for a very, very long
time – unless one drops the tube! This is because the
qualities of the valves combined with the circuit in which
they function will extend their life to the utmost limits,
very, very much beyond 10,000 hours.

The L-5000 DHT is Allnic Audio’s best line stage
preamplifier. Like all Allnic Audio products, it uses
Permalloy (Iron and nickel alloy) for its transformer
cores. Allnic is grateful to Mr. G.W. Elmen of Western
Electric for inventing Permalloy for transformer core use,
and in so doing, providing an enormous service to
recorded music listeners everywhere.

The L-5000 DHT has the following features:

 Line output transformer coupling – The L-5000 DHT is

“transformer coupled”. In tube amp circuitry, there are
two coupling methods; one is capacitor coupling and
the other is transformer coupling. Capacitor coupling is
the traditional, low cost method. It is somewhat stable
but transfers only voltage, not wattage (i.e., not real
energy). With transformer coupling, about 90% of real
wattage is transferred (there is still a transformer loss
of about10% of wattage – voltage is not affected).

Transformer coupling is superior to capacitor coupling.
However, all the advantages of transformer coupling
depend on the quality of the transformer and on the
choice of tubes. Allnic Audio manufactures its own
transformers and uses what it views to be the best core
material, Permalloy. Allnic Audio's unprecedented,
wide (16Hz ~ 75kHz, -3db), low distortional, and ultra­ultra-flexible (up to 50kHz square wave response)
output transformer helps Allnic Audio to realize the
ideal transformer coupled preamplifier. Of course, gain
tubes are also carefully selected for three critical
factors for function with the Permalloy output
transformers: high gm, low internal resistance and high
mu.

 Constant and low output impedance – One of the

benefits of transformer coupling is that it facilitates
constant low output impedance. Low output
impedance is critical to the design of a good
preamplifier. The L-5000 DHT has a 120 ohm (120Ω)

constant output impedance at all frequencies. In
capacitor coupling (C-R coupling), a “cathode follower
circuit" is usually used to lower output impedance.
Unfortunately, this method of lowering output
impedance is accompanied by high distortion and has
an "L" shaped output impedance curve. Please
compare the two graphs below, especially for low
frequency response.

 No negative feedback design

 Advanced tube technology voltage regulation - For

quieter and more dynamic operation, the L-5000 DHT
has an ultra high speed automatic voltage regulation
circuit, utilizing vacuum tubes. This also protects the
amplifying tubes from change in the AC line supply
and copes with any abrupt, internal current demand.

 New vacuum tube damping technology – Allnic

Audio’s patented "Absorb GEL tube damper"
technology prevents harmful vibrations from
reaching the signal / gain tubes and, therefore,
prevents microphonic noise propagation in the tubes.
The Allnic Audio Absorb Gel damper technology
effectively solves a problem that plagues most tube,
and especially DHT, amplification systems. Provided
other tube components do not introduce
microphonic noise into your system, with the Absorb
Gel damping system, you will enjoy a degree of
transparent sound that will surprise and please you.

 Precision attenuator volume control – The L-5000

DHT does not employ a digital IC volume control or a
low-cost carbon film volume control with a motor.
Allnic Audio has developed a precision oil clutched
motorized attenuator; the L-5000 DHT has no (± 0db)
channel unbalance at any volume level.

 Pure Class A operation

 Pure balanced output stage

 As are all Allnic Audio products, the L-5000 is fully

RoHS (EU Reduction of Hazardous Substances
regulation) compliant in construction and materials

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WHAT’S IN THE BOX?

Please check that the shipping box contains the following:

 One (1) Allnic L-5000 DHT Preamplifier – in natural

aluminum or black, depending on your order
specification

 One (1) power cord
 One (1) remote control
 One (1) Gel socket tube puller and instructions
 Two (2) x AAA batteries for the remote control

(loaded in the remote)

 One (1) Owner’s Manual

Note:

1) The L-5000 DHT ships with the tubes installed.

2) The L-5000 DHT will work with most IEC type
aftermarket power cords. Of course, only you can
determine the power cord that works most
synergistically with the L-5000 DHT in your system.

We advise that you keep the box and other packing
materials that your L-5000 DHT came in. It will be useful if
you sell your L-5000 DHT or in the unlikely event you need
to ship it for service.

SAFETY

 CAREFULLY and SLOWLY remove ALL cardboard

and Styrofoam cushioning material inside the tube
chimneys before operation. DO NOT remove the
anti-vibration rings that are on all the tubes
except the small voltage regulator (6AK6).

 Disconnect the power cord by pulling the plug, not

the cable.

 Keep the power cord away from any heat source.
 Keep the unit away from liquids – do not allow any

liquid to enter the interior of the unit.

 When the unit is moved from a cold to a warm

 When the unit is moved from a cold to a warm

environment, allow sufficient time for any
condensation to evaporate before plugging the unit
into an AC connection.

 Do not attempt any repairs.
 Do not remove the chassis cover without specific

authorization from Hammertone Audio.

 See the notes on “Location, Location, Location”.

CLEANING

A. Chassis and glass

Use only a soft, lint-free cloth dampened slightly with
water only (NO cleaning fluids!) to clean the faceplate,
meter glass and chassis.

B. Connectors

You may use any good quality contact cleaner
recommended for such applications to clean the contacts
from time to time as you deem appropriate.

INITIAL SET-UP

A. LOCATION, LOCATION, LOCATION

Like all audio products using tubes, the Allnic Audio L­5000 DHT needs to be placed on a solid stand in a
location that provides for good air circulation around the
preamplifier.

 DO NOT cover the top of the preamplifier.
 DO NOT place the unit on carpet or foam.
 DO NOT subject the unit to knocks and shocks as

you move it around. This advice is meant
particularly for those who may want to place the
L-5000 DHT on a set of after-market isolation

feet or similar devices. Dropping one side of the L­5000 DHT, or the whole unit, is not a good thing.

Output
Impedance

Frequency

(Allnic LCR Output Impedance Curve)

Frequency

(Traditional CR Type Output Impedance Curve)

Output
Impedance

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 DO NOT place the unit near a strong light or heat

source.

 DO NOT place anything heavy on the unit.
 DO NOT allow rubber or vinyl materials to rest on

the unit’s chassis for long periods of time. This
could discolour the metal.

 DO place the unit on a shelf or stand that is stable

and not subject to vibration or sudden shock.

 DO consider using a high quality power cord and

inter-connects, both inputs and outputs. The L­5000 is a highly sensitive piece of electronic
equipment designed for neutrality and will output
what you put into it.

 DO try to place the L-5000 DHT away from major

sources of RFI and EMI; though well shielded, the L­5000 DHT will function best away from large power
transformers and other sources of such
interference.

B. POWER CONNECTION

The L-5000 DHT uses a standard three prong male IEC
connection for AC input. You need to use a power cord with
a female three prong IEC connector at one end.

To the left of the IEC connector (facing the left side of the
unit as in Figure 1), there is a power on-off switch. Leave
this switch in the OFF position – that means the switch is
pressed “down” at the bottom - while you make all initial
connections.

The L-5000 DHT you have purchased is set internally for AC
110/120 volt – 60 HZ operation. There is no way to change
this to another AC setting without return of the unit to the
factory for re-wiring, at the owner’s cost, including
transport both directions.

C. INPUTS

There are five (5) inputs. Line 1 and Line 2 are balanced
connections (XLR type connectors). The remaining 3 line
inputs are RCA type single-ended connections. None of the
inputs is intended especially for connection to any
particular device.

NO PHONO STAGE - The L-5000 DHT is a line stage
preamplifier and does NOT have a built in phono
preamplifier section. You will need a phono preamplifier if
you want to use a turntable with the L-5000 DHT. You can
connect your phono preamplifier to any of the five inputs,
provided you have the appropriate types of connections or
adaptors.

The L-5000 DHT has been designed and manufactured to
work most synergistically with Allnic Audio phono
preamplifiers, pre-preamplifiers, equalization and power
amplification products.

D. OUTPUTS

The L-5000 DHT has three pairs of outputs. Two (2)
output pairs are balanced (i.e., separate ground), using
XLR connectors; one (1) pair is unbalanced, using RCA
type connectors.

One pair of the balanced (XLR) outputs is a “Record Out”
(“rec out”). It is a straight pass-through, unaffected by the
L-5000 DHT’s circuitry, and provides no gain.

The other two pairs of outputs are intended for
connection to a power amplifier. On the back panel of the
L-5000 DHT there is a switch to select either the balanced
or single-ended connections. This selection switch is at
the top centre of the rear panel and labeled “unbalanced
output” (see Figure 2). Please set the output selection
switch to the output connection you are using. If you set
the switch to “balanced” (i.e., XLR – switch pushed to the
right, looking from the rear) and then connect your cables
to the RCA outputs (“main out 2”), audible hum will be
introduced.

You may use both the balanced and single-ended RCA
outputs at the same time; for example, if you run one
pair to your stereo amplifier and the other to a powered
subwoofer (or a pair of them). In such a case, set the
output selection switch to unbalanced (RCA – switch
pushed to the left). This will avoid the introduction of
hum.

E. PHASE SWITCH

On the right hand side of the top deck of the chassis,
there is a phase switch. This switch is a 180 degree phase
switch; phase is either normal or inverted one hundred
percent, depending on the switch position. On initial
connection, set the switch to normal. Depending on the
phase your sources output and their facilities with regard
to phase, you may want to switch to inverted phase
sometimes. Phase issues generally will result in lack of
bass and/or focus of the stereo image (See Figure 3).

F. REMOTE CONTROL

The remote control provides the ability to remotely:

 Select the line source input using either the

numbered buttons or the horizontal arrow buttons

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to each side of the Mute button (Please see Figure 4).

 Control the volume level using the up (louder) and

down (quieter) arrow buttons above and below the
Mute button. After about forty (40) seconds, the light
above the “operate”/”mute” button will illuminate.
The L-5000 DHT has a “soft start” delay for the tubes
in order to extend tube life.

 Mute the volume using the button labeled with a

speaker cone with an “X” across it, located between
the “CH” and “VOL” arrow buttons. Depressing the
mute button will run the volume control down to
zero. To raise the volume again after muting, press
the mute button to take the volume level to where it
was prior to muting.

 There is no power on/off on the remote. The L-5000

DHT on/off control is on the face of the chassis only.
This should help prevent accidental powering off of
the L-5000 DHT when the power amps are still on.

INITIAL POWER-ON

Once you have your L-5000 DHT in place and all
connections have been made to your sources and
amplifier(s) and the power cord is installed and plugged
into an AC receptacle, you are ready to turn on the power
for your L-5000 DHT. Before you power up the L-5000 DHT,
though, be sure you have:

 CAREFULLY AND SLOWLY removed ALL the cardboard

cushion materials from inside the tube chimneys

 ensured the batteries are in the remote control – if

not, insert the batteries (by removing plate on the
bottom of the remote control).

 selected the output connections that you want to use,

single ended (RCA) or balanced (XLR), on the switch at
top centre on the back of the preamplifier

 turned the volume down on or muted the L-5000 DHT
 checked that all your connections are snug

Also, be sure you have manually turned the volume control
on the front panel to the extreme counter-clockwise
position (minimum volume).

When the Allnic L-5000 DHT has powered up internally and
you have depressed the far left hand button marked
“power” on the front panel, the following will happen on
the front panel (Please see Figure 5):

 the light above the “power” button will illuminate.
 the meters on the front panel will illuminate.
 the light over the line source button that is

depressed will illuminate

 after about 40 seconds, the light over the mute

button will illuminate

The Allnic Audio L-5000 DHT is now ready for operation.
At this point, you can power on your stereo power
amplifier or mono-blocks.

OPERATION

From this point on, operation is straight-forward. All
functions are controlled from the front panel or the
remote control. Of course, BE CAREFUL about differences
in gain between your sources. Generally, disc players and
tuners will have greater gain than phono stages. That
means the volume setting for listening to your turntable
might be too high for listening to CD’s.

To avoid surges to the speakers, it is best to change from
input to input only with the “operate” button set to mute
(the light above the button will not be illuminated when
the button is in the “mute” position).

When you are finished listening, turn off your stereo
power amplifier or mono-block amplifiers. Then turn off
the L-5000 DHT, using the remote control or depressing
the power switch on the front panel. The power switch
on the rear panel should stay in the “on” position – this
will keep key circuitry warm, and your L-5000 DHT will be
ready to play when the soft-start turns on the L-5000 DHT
next time you want to listen. Turn off your sources last.

THE CURRENT METERS

These illuminated meters indicate the current supply to
the gain tubes in the L-5000 DHT. They are indicators of
failure or damage to the function of the unit. There is one
meter for each channel. The needle should be between
the two parallel lines just left of centre on the meter face.
Any failure of the tubes or circuits in one or the other of
the L-5000 DHT’s channels is indicated by the needle on
the meter for the respective channel moving out from
between those two parallel lines.

 If the needle has moved to the left of the parallel

lines on a meter, it means that one or both of the
gain tubes (3A/110A or 3A/109B) for that channel
is failing.

 If the needle on either meter moves to the right of

the parallel lines, it means that one or the other of
the rectifier or voltage regulator tubes (7233 or
6AK6) for that channel is failing.

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In the case of any failure indicated by the meter, please

contact Hammertone Audio for assistance.

TUBES

The L-5000 DHT uses the following tubes (see Figure 6):

 Two (2) x 6AK6 or 6485
 Two (2) x 7233
 Two (2) x 3A/110A (or MR0 PT8, if requested for

lower gain)

 Two (2) x 3A/109B

All consequences of changing or attempting to change
tubes are borne by the user unless by express agreement
between the owner and Hammertone Audio. Allnic Audio
and Hammertone Audio are not liable in any way
whatsoever for any injury or loss incurred by the user or for
damage to the L-5000, any of its parts, or tubes or
replacement tubes resulting from the user changing or
attempting to change tubes.

SPECIFICATIONS

FOR THE ALLNIC AUDIO L-5000 DHT LINE STAGE
PREAMPLIFIER

 Inputs: Line level × 5 pairs

(Balanced × 2, Un­balanced (RCA) × 3)

 Outputs: Balanced × 2 pair (1 record)

Unbalanced × 1 pair

 Input Impedance: 10kΩ Balanced/Unbalanced

 Frequency Range: 20Hz ~ 20kHz (FLAT)

16Hz ~ 75kHz (-3dB)

 Voltage Gain: +18dB

 THD (1kHz): Output 0.3V, 0.06%

Output 1.0V, 0.16%

 S/N Ratio: -90dB (CCIR, 1kHz)

 Tubes: 3A/110A or lower gain

stage equivalents MR0 PT8
or MR0 TS8 x 2 (1stgain
stage); 3A/109B × 2 (2nd–
output - gain stage –
equivalents are CV1671
and 4021a;
7233 (no equivalent) × 2
(Rectifier);
6AK6 (equivalent to
A4361, CV1762) or 6485
(similar to 6AH6, 6AH6WA,
6AH6S, CV2521) × 2
(Voltage Regulator)

 Fuse: 2A 250V slow blow

 Tube chimney

screws: 2mm Allen head

 Dimensions: 430mm (16.9291 inches)

(W)
351mm (13.811 inches)
(D)
211mm (8.3 inches)
(H)

 Weight:19.1 kg (42 lbs) unpacked. Packed

shipping weight in original shipping material is 21
kg. (46.2 lbs)

 Maximum Output: 20V RMS (Non-clipping)

 Output Impedance: 120Ω Constant

 Power

Consumption: 30W at 110/120V / 60 Hz

10

WARRANTY

All Allnic Audio amplifier products are warranted against materials and manufacturing defects
for parts, excluding tubes, and labour for two (2) years from date of purchase. Tubes are
warranted against materials and manufacturing defects for one (1) year from date of purchase.
The warranty is transferable for the balance of the original purchaser’s warranty period,
provided, as stated below, no unauthorized repairs or modifications have been performed on
the product. Date of purchase is the date indicated on the invoice for the product issued by
Hammertone Audio.

For the warranty to be valid, a defective product must be returned to Hammertone Audio for
service prior to any unauthorized attempt to repair. Any repair work on an Allnic Audio product
not specifically authorized by Hammertone Audio will void the warranty on the product.

11

FIGURES

Figure 1 – L-5000 DHT Left Side Panel View

Figure 2 – L-5000 DHT Rear Panel View

Figure 3 – L-5000 DHT Phase Switch

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Figure 4 – L-5000 DHT Remote Control

Figure 5 – L-5000 DHT Front Panel View

13

Figure 6 – L-5000 DHT Internal (Top) View

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52 Magic Drive, Kelowna, British Columbia, Canada V1V 1N2
Direct Telephone: [phone]; Fax: [phone]
email: [email protected]
Website: www.hammertoneaudio.com