Text preview for : VTL Book - Parte 3.pdf part of David Manley VTL Book The Vacuum Tube Logic Book - VTL - No Review
Back to : VTL Book - Parte 1.pdf | Home
Owner's Manual
Section
Vacuum Tube Logic of America thanks you for selecting our tube electronics
for your stereo system. In the interests of getting the best performance out of
your equipment, may we ask that you take the time to read through this manual
first, please? if you wish to know still more about us and all our equipment, you
might consider investing in a copy of The VIL Book: if so, please write enquiring
about ordering it.
Much of the information contained in this little manual has been accessible
only in technical literature long out of print. Some of the concepts and ideas
have never appeared in print at all. Most has been gleaned from 30 years in the
professional recording industry, wherein we have proven out our circuitry and
design philosophies. We hope therefore that you will find yourself both informed
and entertained.
This is about the exotic and beguiling hobby (art, one might say) of at-
tempting to create the illusion of live music in your home. Before going into any
technological details about Vacuum Tube Logic equipment, it might be in order
to state that our on-going goal is to offer discerning audiophiles premium-quality,
musically accurate equipment at a price that allows us to eam a conscienable
profit, and to produce this equipment with a fierce pride. It is this pride and
dedication to quality (and reliability) that makes it possible for us to offer our
(conditional) lifetime warranty quite possibly one of your major reasons for
choosing VTL equipment in the
-f,rst place.
We believe deeply that well-designed and executed vacuum tube electronics
have continuously demonstrated their musical superiority over other technological
breakthroughs. No question, the transistor is an invention that borders on the
miraculous; but we believe it has its best uses in computers and calculators,
radios and robots. Ask the musicians; hear the truly great recordings made with
68 THE VTL BOOK
famous tubed microphones; pay heed to the (oh so rare) knowledgeable reviewers.
But then just listen, and you'11 know.
True, tube equipment has never been inexpensive to buy; and true also
that a very good value-for-the-money deal is available to the consumer nowadays
when purchasing a $300 stereo rack from a depaftment store a direct result of
the low-cost transistor in mass-production. -
Such mass production, of course, is not without its price. Nothing will
demonstrate this more than actually listening to our equipment, and seeing (hear-
ing, feeling) this for yourself. Quite frankty, the difference is not subtle.
Power Requirements
All VTL equipment is designed to operate on the various AC voltages around
the world. The mains transformers in our units have multi-tapped dual primary
windings (for series or parallel connection) that use the following color coding:
Power Transformer Color Code
Volts Pnru,qnv 1 Pnruanv 2
0 Blacr OnrrvcE
100 BnowN Yr.llow
120 ReoAVurre BluEAVurrr
127 Reo Blua
Hence any line voltage from 100 to 254 volts can be configured; some exam-
ples: black and orange are joined together as 0 volts, with red/white joined with
blue/white as 120 volts to form the standard U.S. mains/power input, putting the
two transformer primary windings in parallel. For 240 volt operation, the pri-
maries would be connected in series, with black alone being 0 volts, red/white
( 120 volts) connected to orange (0 volts of the second primary) with suitable
insulation, and blue/white being the 240 volt termination.
From these examples, it can be seen how 100 volt operation (Japan) is
connected in parallel, and how 220 volt operation (most of Europe) is achieved
with the primaries in series. Of course, we do not classify this operation as a
modilìcation provided it is undertaken by a qualified technician or a competent
dealer.
However, we stress that the equipment should not be opened for any reason
by anyone other than experienced, qualified technical personnel. Tube equipment
OTHER ANCILLARY EQUIPMENT 69
contains extremely high voltages 400 to 600 volts Direct Current which
- long after the unit has been switched off
can cause a nasty or even lethal shock -
and disconnected from the mains supply. This is due to the inordinately high
capacity banks utilized in VTL equipment. A trained technician knows how to
safely discharge these capacitors before commencing any work on the unit. From
the user's viewpoint, our equipment is totally safe to operate and is extremely
reliable under normal conditions of usage, provided only that it is not tampered
with by unqualified persons.
General Operational Notes
We do not recommend that the equipment be left permanently switched on, only
for the reason that this is wasteful of both electrical energy (money, therefore) and
tube life. You will find that VTL equipment sounds excellent right after switch-on,
though of course we agree that all equipment improves sonically after a longer
warm-up period. Interestingly, it is not the tubes themselves that benefit from
the longer warrn-up (they come up to peak operating temperature after four or
five minutes) but the temperature settling of the capacitors, resistors and the wire
in the circuit itself, plus the transformer's wire and core material, that enhances
sonic performance after the equipment has thoroughly warmed up.
On the subject of mains/power, please do not be alarmed when some of our
larger power amplilìers emit an audible acoustical "thump" on switch-on. This is
caused by the residual magnetic energy in the power transformer as it undergoes
pole reversai. Likewise, the seemingly over-bright "flash-glow" upon switch-on
of the smaller (input) tubes is no cause for concern. This is the result of their
heaters being cold, and hence of lower initial resistance. Also, the 12- series
of tubes has a greater portion of the heater winding exposed (i.e., not inside the
cathode encÌosure).
Always install our (and other) equipment with sufficient air space around
it. We disapprove strongly of stacking, and the shapes and sizes of our various
models are specifically designed to prevent stacking.
If you prefer to see and commune with the warm, friendly glow of the
amplifler tubes (we do), there is no harm in operating the ampliflers open topped,
but we suggest then that you fit our finishing brackets (which are neither intended
to be used as nor called "handles") which serve the dual purpose of giving the
unit a finished look and affording some protection from feather-dusters or flapping
dust cloths. Also, we think it would be obvious not to floor-mount the amplifiers
if your family includes toddlers or pets. Strange, is it not, that some people who
would not leave a delicate instrument such as a fine camera lying around for fear
that a child or dog might damage it will exercise no such common sense when
that fine instrument might instead damage the child or dog.
70 THE VTL BOOK
Other Ancillary EquiPment
Though we dearly wish it otherwise, we cannot insist that our power amplifiers be
driven only from our own preamplifiers. We do not, however, think it requires a
great deal of understanding to conclude that our designs are conceived to perform
at their best in concert, so to speak. But for those who do, for reasons of their
own, choose to "mix and mismatch" various brands and designs, let us please
spell out parameters.
First, though this was not intended by design, most VTL preamplifiers will
drive almost all other amplifiers, even solid-state, to a lesser or greater degree
of success. Matters of impedance-matching and drive-voltage requirements do
have to be borne in mind, however, especially with some solid-state amplifier
equipment. In the latter instance, a coupling-capacitor is often part of lhe am-
plifters' input circuitry. Even though an acceptable impedance match (commonly
in the 5 k, l0 k, or 20 k vicinity) will occur, this capacitor may be of too low a
capacity to allow full low-liequency response from the very low (about 30 ohms)
impedance of our most senior models (SuperdeLUXE, Ultimate, and Manley
ReferenCe) of preamplifier. The only solution is to change the capacitor in the
'foreign' amplifier to one of higher value on the order of 10 microfarads. C)ur
Maximaf preamplifier was specifically designed to drive tube amplifiers and has
an output impedance of approximately 5 k, so it too can be used with many
(though delìnitely not all) solid-state ampliflers.
If you want to put a tube preamplifler in front of your favourite solid-state
power amplifier (and yes, we do commend your thinking) the best-suited to all
is our deLUXE preamplifier (available with and without MC stages) because its
main-buffered output is on the order of 300 ohms the ideal solid-state match.
All pure-tube amplilìers are upward of 50 k - input impedance' a so-called
"bridging input" in the sense that the amplifier presents little or no load to the
preamplifier output.
As regards input sensitivity, however, VTL amplifiers are somewhat more
sensitive (easier to drive) than others, requiring approximately 800 millivolts
rms tor full output. This thinking is planned around the "dBm Standard Scale",
whereas there are many amplifiers around (mainly of older design) that have a
full-power drive sensitivity of 1 volt up to as much as 1.8 and even 2 volts rms.
These are designed with the "dB Standard Scale" in mind. The point here is one
of gain scaling (sadly, an almost never discussed subject) wherein one learns to
apply rhe benefits of judicious component matching. Consider a (hypothetical)
worst case: a lower-output moving-coil cartridge with, say, only 0.3 mV output
chosen to drive a preamplifier that is optimised for cartridges of 0.5 mV upwards,
which is now interfaced with an amplilìer requiring, say, 1.8 volts of input to
drive it to full output.
THE VTL RANGE 71
Painting the picture even darker, let us say the preamplifier was optimised
to drive a I volt senstitive power amplifier of, say, only 50 watts power output
at 8 ohms (nominal) loudspeaker impedance. You can see where we're heading,
but let us worsen the proposition further by adding that the loudspeakers chosen
to complete this disaster were to be of the 4 ohms variety (not the 8 ohms the
amplifier was configured for, thereby reducing its power by 257o) and then let
us nominate that these loudspeakers were only of 84 dB efficiency at 1 watt at
I metre. There's a word to properly describe such a system, but the writer is
too refined a fellow to even think it. Now it can be plainly understood that this
system would suffer in the worst way from poorly chosen interfaces as regards
gain-scaling, as well as power/impedance/efficiency mismatches that would result
not only in disgusting sonic performance due to wrong (insufficient) excitation
voltages, but also in unacceptable noise levels.
To complete the topic of interfacing VTL amplifiers with other preampli-
flers, we must include sundry active gain-bearing crossovers, "equalisers" pro-
vided by some loudspeaker manufacturers (many of which should more accurately
by described as "design deficiency correction devices"). We need also to explain
one of the most worrisome problems often encountered with incorrectly chosen
"other brand" preamplilìcation equipment. This conccrns the matter of DC volt-
age present atlin the outputs. An alarmingly large proportion of preamplilìcation
equipment evinces this defect: the most common offenders are the more compli-
cated designs whcrein some foxy servo circuitry exists for the express purpose of
"servo-ing" the DC.
Just as bad (though this is a less well perceived and understood problem) is
the presence of instability, which manifests itself as oscillation at an extremely 1ow
frequency, usually under 10 Hz. Though small in magnitude, this is able to pass
through the coupling capacitors because of its ultra-low frequency (close therefore
to pure DC). This AC signal, now masquerading as quasi-DC, enters our VTL
amplifiers, whose design criteria specifically demand that the power band pass
be extraordinarily wide. As a result of this, we can promise our much-admired
tighter-than-solid-state bass. So this spurious oscillation progresses, with ever-
increasing amplification, right up to the output tube's control grids, whereupon
it "swamps" the essentially required negative DC bias voltage. Starved of bias,
the output tubes will glow cherry-red on their anodes (plates) causing them to
self-destruct.
Now do you see why we refuse to grant any kind of warranty on amplifier
tubes when the unit is not driven by a VTL preamplifler? You might not agree,
but you'll surely understand our reasoning.
{:
72 THE VTL BOOK
The VIL Range of Models
We take a fair amount of criticism for producing a large number of different
models, mainly from people who have a parlicular axe to grind. And yes, it's
true that we could make more money and have an easier life if we just made
one amplifier and one preamplifler. our reason for offering such a wide range
of models is based on our policy of making audiophile quality available at all
price levels. People tend to think of tube equipment as the highest of the High
End and priced as such. We take great pleasure in offering premium musical
reproduction to the disceming but less-affluent audiophile, as well as catering .to
those not restricted by budget.
The Maximal
The MaXimal has small screwdriver-adjustable potentiometers on its rear panel,
which gives an increase/decrease of almost 5 dBs on each channel to better
enable its usage with a wider variety of cartridges and amplifiers. As a secondary
function, this little pre-set helps adjust the balance contlol to be 'centled' in its
mid-position.
The topology of the Maxim?l is two 12AX7A triodes per channel for the
PuoNo section with 'active' RIAA and two 620ll12Nl7WA triodes per channel for
the LtNe section , with the selector switch and volume control being electronically
located between the phono and line stages. The 'line stage'has a tasteful amount
of overall negative feedback; this loop includes both the balance control and the
pre-set adjustment. Certainly, it was not designed for the very low-output moving
coils, but it will accept all but the extremely low-output cartridges (under,15 mV)
by the extension afforded by the rear pre-set adjustment. N.B.: The pre-set is
factory set in its "mid" position and also for accurate balance control positioning:
do not alter the settings inadvertently do so only when wishing to reduce or
increase gain for matching purposes.
-
The Maximat has an extremely "stiff" B-rail power supply (over 1000 mi-
crofarads), and a regulated 12 Volt DC supply for its tube heaters.
The deLUXE
Our second preamplifier is called the "deLUXE" in our literature, though many
call it the "AmeriCan deLUXE", because it was the first model we manufactured
in the USA, and to distinguish it from its older "British deLUXE" brother. It is
from the deLUXE preamplifier that the family topology starts to develop in our
range of four preamplifiers. In its standard and simplest form, the deLUXE offers
the following lacilities: Auxrlrnny, CD, Teps and TUNER as line-level inputs plus,
of course, the PrroNo input.
Let us examine the PuoNo input first as to its intended cartridge matching
and best utilization. The input here is designed to be pretty flexible as regards
THE DELUXE 73
moving-magnet and many moving-coil cartridges and, believe us, this was a
tricky problem to tackle [see Pnr,ruelrrrERs]. The PHoNo input is loaded with the
recognized standard 47 k Q load-resistor.
Impedance and loading considerations aside, the deLUXE has sufficient
gain when used with one of our amplifiers to handle most, but not all, moving-
coil cartridges down to about point-five millivolts, and even to point three, with
an acceptable noise-floor. However, we would call less than 0.5 mV distinctly
marginal; perhaps not for reasons of noise, but certainly of insufficient excitation
voltage.
Optional MC Step-Up. We believe the only proper way to deal with low-output
cartridges is to have a dedicated stage to boost them right at the input, which is
why we offer this as an extra option on all our true High End units, which
include the deLUXE. Note that this addition is not a retrofit option, because
in the deLUXE the MC step-up is hard-wired in (i.e., not able to be instantly
switched out/over to MM/high-output 'coil mode as in the Super deLUXE and
Ultimate).
So if a low-out MC is in your present or future, it is smart to order the
deLUXE with the MC stage built-in; even though it is hard-wired into the circuit,
a competent technician can by-pass the MC stage and put the unit into the MM-
mode. Equally, the MC step-up can be re-connected later with some precision
soldering.
Besides the input options, our deLUXE is pretty unique in that it offers
three oùtputs which can all be used simultaneously if desired:
a) The Recono out in the main socket cluster comes from the selector-switch,
so it can drive most high-impedance tape-decks. Since this point is also at the
"top" of (1.e., before) the volume-control you should disconnect your recorder's
input if you know it to be under 100 kQ input impedance when you are not
actually tape-recording, because it will load, and therefore impinge, on the sound
of the repro-system.
b) The HrcH-Irr.rpnoaNcE output (the last pair of sockets in the main cluster)
comes from the line-amplifiers final anode. It has therefore the fullest output
voltage available from the preamp, but at a relatively high impedance: approx-
imately l0 kQ. It is a very useful output indeed when used with high-quality
interconnect cables over a distance of no more than ten feet or so, but only into
a VTL tube or other tube amplifier of no less than 50 kQ input impedance.
This output should not be used with any solid-state amplifier. The reason we
offer this Hl-Z ovt is twofold. Firstly it is "good for sound" to avoid the cathode-
follower (buffer) stage if you can because cathode-followers have an insertionloss
of about ten percent, and this extra ten percent will improve the signal{o-noise
74 THE VTL BOOK
ratio; besides that, any stage that can be left out is a great stage to leave out.
secondly (nobody ever spots this), the HI-z out can be used with a specific
high-pass series-capacitol
- of a bi-amp'ed
16 fldys the mid/treble tuhe amplifier
system. thereby leaving. .
-
.
c) The Low IupeoeNce cathode-follower output (the pair of sockets on their
own at the rear right) available to drive the bass amplifier, which could be tube
or solid-state since the impedance at this output termination is of the order of
300 ohms. The Lo-z buffered output of the deLUXE can drive any amplifier
over any length of cable.
A unique feature of all the vTL preamplifiers is that the balance control
functions via the feedback loop and not by way of an additional half-set volume
control in the signal path, the more commonly used method of controlling balance
that certainly impinges itself on the signal. The separately-cased power-supply for
the deLUXE is mounted on the common l9-inch panel but offers the desirable
benefits of an outboard supply for EMI isolation (hum and other interference).
The power-supply for the deLUXE drives both channels; the 12-volt DC
rail for the heaters is fully regulatecl, while the high voltage (B rail: approxi-
mately 260 VDC) achieves its regulation through its massive capacity bank and
pi-f,ltering, which totals 1280 microfarads a Joule-content not found in many
power amplilìers, let alone preamplifiers.
-
The topology overview then for the deLUXE consists of (per channel):
a pair of triodes, in cascade with each channel in a separate envelope, which
comprises the phono-stage with the RIAA actively embracing the pair (by selec-
tive frequency feedback [see Pnr,rrrars]) entering the selector switch and volume
control, then into the line-stage which comprises another pair of cascaded triodes
also embraced in a discreet feedback-loop which contains the balance-control. At
this point the high impedance output is availabte before the signal enters the final
cathode-follower buffered (low impedance) output.
we intend the deLUXE preamplifier to be used in systems which are limited
only by the quality-cost, therefore, of the cartridge, arm and turntable. By this we
mean that we don't envisage a Lapis Lazuli cartridge on a Goldmund Reference
table driving a preamplifier in the thousand-dollar bracket: however, if someone
chose this match, we would neither laugh nor be embarrassed'
The Super deLUXE
our rhird unit is called rhe "super deLUXE" in our literature. The super
deLUXE is most closely related in topology to the smaller deLUXE and the older
British deLUXE. but with more features and refinement. The more important
of these are:
THE SUPER deLUXE 75
a) Each audio channel is complete on separate boards mounted several inches
apart.
b) The preamplifier has an outboard (single circuit) power supply interlinked
I
with an umbilical cord; the intention being to locate the power supply for lowest
noise pick-up by the PnoNo cables.
I
c) The Super deLUXE is standardly built and offered with a switchable (in
or out) MC step-up stage which has selectable cartridge loads. We list the Super
deLUXE as being available for MM only, at three hundred dollars less, but we
have had no call for this probably because users of not-the-most-expensive
- the deLUXE and those using the most costly MM
MM cartridges correctly choose
(or a pricey high-output 'coil) go for the MC Super deLUXE or Ultimate.
d) The Super deLUXE has a totally buffered (separate cathode-follower) low-
impedance RECORDING output capable of driving any recorder (even 600 ohm
studio-line) or outboard amplifier/surround-sound device (or even a dead short)
without loading the main signal path in any way.
Please do not attempt to engage the MC stage (on older SDL models
with internal switching) or even open the case unless you are somewhat
of an advanced amateur - technician. Dangerously high voltages are present
-
inside our preamplifiers, even many days after they have been switched off,
because of the energy stored in the extremely high-capacity banks. If you are
the kind of person who does not cope well with electrical matters like the changing
of a household fuse, please take the unit to your dealer to effect any change-ovcrs.
The Super deLUXE preamplifier is routinely shipped in a moving-coil mode set
to handle any MC cartridge.
The MC stage's selection and load-switching requires some careful under-
standing. First and foremost, please know that it is unique in that it does not
invert the phase; all step-up transformers do, as do other outboard tube set-up
pre-preamplifiers. Inside the case at the left and right rear of the mother board
there are two blue DIP switches with contacts numbered I through 8, selectable
as follows:
DIPS 7 and 8 (together): switch the MC stage into the circuit. In fact, either one
does this and the switch has very high quality gold contacts; we just use two to
increase the contacl integrit y.
DIPS 1 through 6 (separately and/or together): starting from 100 ohms (DIP 1)
and increasing in values up to 4700 Q (DIP 6) these switch in the loads which,
of course, also affect the gain. The loads are applied in parallel so that by, say,
switching all the DIPs to "on" you would have 100, 470, 1000, 1000, 2700,
plus 4700 ohms all combining in parallel which will bring the lowest value
76 THE VTL BOOK
(100 ohms) down to around seventy ohms an extremely low load indeed
- be used to determine the exact
lsee also Cenrnr»cesl. The following formula may
loading:
1
l)
t\tornt- t t
_:- _t- _:-- _r - I
Fr fi.., 1_
' R.r
So in the abovementioned example where all DIP switches are selected, the total
resistance would be
Rr orol = i1r1t1
roo' 4;o' looo' tooo' 2ioo' +;oo
This gives a total resistance of
I
Rr^+.r= =68Ohms;
0:01471
Notice that, since we're working with reciprocals, the larger values (e.9., 2700
and 4700 ohms) bring down the total resistance less than the larger values. The
above formula is included only for the sake of completeness; we recommend that
you let your ears decide what is best in your individual situation.
The point is that regardless of what any manufacturer offers as what they
know to be the optimum loading for a given cartridge, most audiophiles prefer to
disregard this information and go with what sounds best in their actual system. As
far as cartridges go, we actually agree with this philosophy, because cartridges
are delicate little devices that vary greatly from (new) sample to sample; they
age or "bum-in" differently, can be easily damaged in a marginal way that affects
their sound performance and produce totally different read-outs with various arm-
masses, VTA,tracking-weight et cetera.
So regardless of the stated load for a specific cartridge, the setting of the DIP
switch will be mainly chosen by ear. No harm can be done; we send the units out
selected for a load of approximately 400 ohms, which seems to us a reasonable
average for most MC's. Again, and we never underestimate this concept, let us
suppose that yours is an ABC cartridge which the maker and common opinion
agree is best loaded by XYZ ohms; but you happen to have a DEF amplifier
driving GHI loudspeakers via ZIP cable... The net result could easily be that by
switching in, say, 100 ohms of load to a cartridge designed for 1000 ohms that a
preferable overall sonic balance was achieved in that particular system and room.
Who could argue?
The Ultimate Preamplifier
fair amount of 'stick' for the immodest-seeming name we bestowed
Yes, we take a
upon this unit. But we can explain! By 'Ultimate', we mean that in the first
THE ULTIMATE 77
instance we have given our best shot at the actual electronic circuit design and
totally dual-mono execution. These very circuits and layout techniques have
been tested and proven in recording chains where price was of no consequence.
Furthermore, we explain that the intent of the word 'Ultimate' is to allow the
purchaser the choice of custom-specifying his requirements.
The board design of the Ultimate preamplifier has installation-ready op-
tions, which include a two-way crossover (at between 750 to 2500 Hz) for classic
bi-amplifying; separate or "Quad" outputs intended for driving four amplifiers
for surround-sound (altematively, the extra buffer-stage may be used for isolar
ing the Rrcono output); as well as our innovative "Floating Symmetrical Mode"
technology as an Òptional extra (approximately $700 and supplied with an XLR
cable).
The Ultimate's total dual-mono approach, with a fully-regulated and ultra-
high capacity power supply positively does enhance imaging, staging and posi-
tioning of lateral information. Please note that we did not (and never will) fit
two (highly inconvenient) separate volume controls; we feel this is unnecessary
enslavement to dual-mono after all, the 'marriage' is only by a mechanical
shaft commonly rotating the
- 'wiper' on the actual resistive traces with certainly
adequate separation to ensure zero channel-to-channel leakage at this point. Not
so with the selector-switch, which is why we use one for each channel.
Experience with mixing-consoles has taught us that compact rotary selector-
switches can leak within decks and deck+o-deck; larger ones are not available
with sufficiently good contacts, being intended for higher current rather than
higher signal-integrity purposes. Even so, we choose in the Ultimate to'double-
up' contacts, being over-conservative rather than allowing just one set of switch
contacts to handle the signal alone. Again, with the 'balance-trim' control we
felt that two separate controls were desirable. This was in the belief that, within
minor adjustment limitations, the balance-control largely remains at or near a
given setting.
' Also, our method of controlling or trimming the channel-balance is some-
what diftèrent from commonly-used circuitry in that ours is based .uound a smali
variation in the feedback loop. This is because we do not like either the insertion-
loss gain-wise of an additional volume control in the circuit nor its inherent dele-
terious effect on the signal path. If we can easily hear when a balance-control
of the 'pre-fade' variety is switched in or out of a circuit then we feel it is
not a permissible or desirable feature. Verily, we would like to omit any form
of balance-control but realise that this is an essential control needed for certain
recordings and sometimes for speaker position corrections (although we prefer
not to think too deeply about this extreme usage of a balance control!)
78 THE VTL BOOK
Another important feature of the Ultimate is its anti-microphonic neoprene
suspension of our non phase-inverting tubed MC step-up stage (also optional) and
phonoÀIeA circuit-board. Even the best tubes are not totally free of micro-
I
phonic sensitivity and this is even more understandable when you realise that the
maximum gain of the Ullimate can be set to some seventy-five-hundred-times
amplif,cation: i.e., one and a half volts rms from point two of a millivolt or
three-quarters of a volt form point one of a millivolt. Truthfully, this is stretch-
ing tube amplification technology to the absolute limit in noise terms, both from
microphony and the Miller/rush effect.
If you will pardon a little digression from the subject at hand, may wè
tell you why we do not feel that a point 08 or point I millivolt cartridge is
a good choice for any tube preamplifier? Quite frankly, we do not believe in
the viability of a point 08 cartridge for any kind of active amplifying device.
Can you contemplate the energy level emanating from such a cartridge at, say,
30 Hz with this frequency attenuated by roughly 18 dB in the RIAA procedure?
There is just not enough excitation energy present to dredge music out of the
grunge in any technology, except possibly with an expensively engineered step-
up transformer from the same manufacturer, which is normally their recommended
method of interface and which may exhibit a tendency to 'ring' besides requiring
extraordinary location-positioning.
Yes, we realise that a miniscule-output 'coil of around point 08 mV can
sound quite alluring to some; they can, like a sixteen-cylinder 500 c.c. engine,
go very fast (but not lor long, and then only with a team of grave-looking me-
chanics in constant attendance). This 'speed' is achieved or increased by the
ultra-lightweight armature/cantilever assembly with possibly only about 50-60
tums on the armature, making the construction a little more possible rather than
'easy
"Too, these units tend to vary greatly from specimen to specimen. With this
type of cartridge it is all too easy to get into the position of "I love this cartridge
for its smoothness but it needs so much damned ampliflcation that its smoothness
is lost in the amplification; therefore I need another ampliflcation system." No.
Sorry. What is needed is a cold beer and a hot(ter) cartridge, in our view.
When ordered with a MC step-up stage, the Ultimate is routinely shipped
with the MC stage engaged (on) and set for a load of 400 ohms, which suits a
large range of MC cartridges.
As to circuit topology of the Ultimate, two Class A triodes in cascade feed
a cathode-follower output stage whose output coupling is via series capacitors at
a very low impedance; the mid-point of these caps supplies the feedback retum
loop, which includes the frequency-selective RIAA circuitry and which returns to
the first cathode via an impedance 'lock-down' circuit.
78 THE VTL BOOK
Another important feature of the Ultimate is its anti-microphonic neoprene
suspension of our non phase-inverting tubed MC step-up stage (also optional) and
phono/RIAA circuit-board. Even the best tubes are not totally free of micro-
phonic sensitivity and this is even more understandable when you realise that the
maximum gain of the Ultimate can be set to some seventy-flve-hundred-times
amplification: i.e., one and a half volts rms from point two of a millivolt or
three-quarters of a volt form point one of a millivolt. Truthfully, this is stretch-
ing tube amplification technology to the absolute limit in noise terms, both from
microphony and the Miller/rush effect.
If you will pardon a little digression from the subject at hand, may wè
tell you why we do not feel that a point 08 or point I millivolt cartridge is
a good choice fbr any tube preamplifier? Quite frankly, we do not believe in
the viability of a point 08 cartridge for any kind of active amplifying device.
Can you contemplate the energy level emanating from such a cartridge at, say,
30 Hz with this frequency attenuated by roughly 18 dB in the RIAA procedure?
There is just not enough excitation energy present to dredge music out of the
grunge in any technology, except possibly with an expensively engineered step-
up transformer from the same manufacturer, which is normally their recommended
method of interface and which may exhibit a tendency to 'ring' besides requiring
extraordinary locat ion-posit ion ing.
Yes, we realise that a miniscule-output 'coil of around point 08 mV can
sound quite alluring to some; they can, like a sixteen-cylinder 500 c.c. engine,
go very fast (but not for long, and then only with a team of grave-looking me-
chanics in constant attendance). This 'speed' is achieved or increased by the
ultra-lightweight armature/cantilever assembly with possibly only about 5G-60
tums on the armature, making the construction a little more possible rather than
'easy'.
Too, these units tend to vary greatly from specimen to specimen. With this
type of cartridge it is all too easy to get into the position of "I love this cartridge
for its smoothness but it needs so much damned amplification that its smoothness
is lost in the amplification; therefore I need another amplification system." No.
Sorry. What is needed is a cold beer and a hot(ter) cartridge, in our view.
When ordered with a MC step-up stage, the Ultimate is routinely shipped
with the MC stage engaged (on) and set for a load of 400 ohms, which suits a
Iarge range of MC cartridges.
As to circuit topoìogy of the Ultimate, two Class A triodes in cascade feed
a cathode-follower output stage whose output coupling is via series capacitors at
a very low impedance; the mid-point of these caps supplies the feedback retum
loop, which includes the frequency-selective RIAA circuitry and which returns to
the first cathode via an impedance 'lock-down' circuit.
THE MANLEY REFERENCE PREAMPS 79
The grounded grid MC stage (or Floating Symmetrical Mode stage in appli-
cable models) precedes the regular 47 kQ PuoNo input and, as stated, all of this
phono circuitry is located on the suspended PCB. The phono output is led to the
selector-switch and on to the top, or high side, of the volume control, from which
point the separate 'record' buffer stage is also driven. The volume control feeds
into another cascaded Class A triode pair which drives the final output cathode
follower, giving a very low impedance, lowered still further by the splircap feed-
back method. The feedback loop contains the balance control, returning to the
line-stage's first cathode. N.B.: the feedback loop can be modified to optimise a
given cartridge/preamp/amplifier/speaker chain and, indeed, may well require to
be so modified to suit other than a VTL interface. Please see circuit schematics
in the appendices for further and more detailed information.
The Manley Reference Preamplifiers
The Manley Designer's Reference Series preamplilìer, though it shares a fair
amount of the Ultimatè's conceptual topology, has some outstanding and unique
features:
1) All audio boards are on our specially-suspended anti-microphony mounts.
2) The switchover between MC and MM occurs on the front panel. This
allows the use of two turntables if so required, or two arms on one turntable
which woutd allow comparisons between two cartridges for rcview or analytical
purposes. (Some people choose to use a moving-magnet for really oid LP treasures
sometimes mono only.)
-
3) The Moving-Coil section, a separate board, is supplied only with our "Float-
ing Symmetrical Mode" technology and entry is via XLR connectors only. Note:
it is vitally important that the arm-wiring for the cartridge connection is con-
nected correctly: red and white are the "high" sides and blue and green are the
"low" sides; above all, these wires must not "see" the arm or tumtable ground or
chassis.
4) The unit has two power switches for its outboard power supply.
Each switch
is adjacent to and linked to its own two-colour LED indicator. The two colours
indicate the power being switched over from "ever-on" (green) during warmup
to "operate" (red) for full-power operation.
5) The moving-magnet or high-output 'coil' stage (which is also in-circuit
when the moving-coil stage is in use) is a 'super-stage' paralleled double triode
which has extraordinarily low levels of distortion due to its huge headroom margin
for very high-output capacitor microphones in the
- a circuit actually conceived
recording chain.
=
80 THE VTL BOOK
6) A totally unique method of volume control found only in calibration in-
struments. For reasons of absolute sonic purity, the volume control itself is a
rotary switch with steps of gradation marked 'coarse'. But because we know
how infuriating it can be when one 'click' is just a tad too soft and the next a tad
too loud, we have fitted a 'fine' vemier-type control across the volume switch,
to make these precise settings possible.
By dint of this last innovation, you will realise that at no time does the audio
signal travel only via a volume-control 'wiper-on-track' mode; the signat path is
straight-through. Likewise, of course, the balance control is a parallel circuit to
the feedback loop.
These features, combined with out proprietary "Floating Symmetrical Mode",
bring a totally new horizon in the art of reproducing vynyl phonograph recordings.
THE VTL COMPACT MONOBLOCK AMPS 81
The VTL Stereo Amplifiers
There are two stereo models (i.e., both channels are on one chassis) in the VTL
range. They share an identical circuit board and can easily be discussed together.
The smaller of the two is the 45145 (which replaced the 30/30) and ir is built on
our 'compact-sized' chassis. We re-designed it in June of 1989, and were able
to "give more for less" defended VTL trait.
- a stronglypower supplies of 500New featurescapacity.
a chromed chassis and "stiffer" dual microfarad
include
The way in which we were able to offer more value was by the gaining of quantity
orders for mail-order and export markets; we were able to pass this efficiency on
to our customers. Old-fashioned, eh? We like old-fashioned values.
The stereo 90/90 (upgraded from our 75/75) offers 15 percent more power
at the same price as the previous 75, and also sports a chrome chassis, of the
larger deLUXE size, plus 1000 microfarads per channel in its power supply.
The 45145 uses Russian military KT66's, while rhe 90/90 employs 6550A's
as before. Both units are ulrralinear in their output configuration: the 45145 is set
for only 5 ohms, while the 90/90 is factory set for 8 ohms (easily reset to 5 ohms
by merely changing the green wire on the red or plus speaker terminal) for the
green/yellow wire.
In their new livery, both of these models have their BIAS test points and
corresponding pre-set trim-pots accessible from the top plate, thereby obviating
the need to open the amplifiers' bottom cover to measure or set the bias. Bias is
determined across l0 ohm cathode resistors which therefore require a DC millivolt
quiescent reading of 300 mv for the 45145 (corresponding to 30 milliamps stand-
ing current), and 350 mV for the 90/90 (conesponding to 35 milliamps standing
current). Their input-driver configurations remain unchanged and are common to
all our amplifiers under 120 Watts: both are 12AT7WA/6201's.
The VTL Compact Monobtock Amptifiers
These amplifiers are 80, 100, and 160 watt units. using a separate monoblock
for each channel really does move one into the best league of stereo reproduction
with demonstrable improvements in imaging and staging brought about by the
separate chassis and grourid paths. Also of course, a monoblock-based system
offers a completely different setup plan than is commonly used for dual-channel
units in that people like to place them very near the loudspeakers to take advantage
of the short path in the speaker cabling. Please take due care and consideration
of pets and toddlers when conremplating this kind of installation: it has become
common-place to site the amplifiers right on the carpeted floor.
We don't recommend this for the pets and toddlers. In addition, a high-pile
carpet will effectively close the vent-slots in the amplifiers' bottom cover, thereby
restricting the upward air flow. It is better to position the amplifiers on a small
82 THE VTL BOOK
stool or stand. If one has not got the pet and toddler factor to consider, it is
advisable to put the amplilìers on a square of wood or particle-board to protect
the carpet and allow air movement.
Our "compact" chassis is about one+hird smaller than our larger deluxe
chassis. We offer several power variants in the series. Constantly criticized for
having too many models, we realised that 50 and 65 Watts were a little close
to each other, and furthermore that higher power was most often wanted in a
monoblock. Accordingly, we developed the 80 Watt monoblock with the price
very close to that of our 65 Watt version. Yes, we will still build the 50 and
65 Watt versions upon 10-pair qùantity orders, which is also the status of our
35 Watt triode monoblocks. Rather than being in standard day-to-day production,
they are built in runs to suit export markets. We also added a 160 Watt monoblock
to the cost-effective Compacl series, built around the same common main board'
The differences between these units are in the tube complement, the power supply
capacity, and the output and power transformers.
The '80' has four Russian KT66 output tubes with a 6201 driver and a
6201 input, along with a 500 microfarad powcr supply and 5 or 8 ohm output
impedance. The'100' has four EL3416CA1 output tubes with a 6201 driver and
a 6201 input, along with a 1000 microfarad power supply and an under-chassis
adjustable output impedance. The '160' has four 6550A output tubes with a 128H7
driver and a 6201 input, along with a 1000 microfarad power supply with a higher
B-rail, and an under-chassis adjustable output impedance.
Yes, we realise that 80 Watts is very close to 100 Watts! The reason for
both models, apart from their price, is similar to that of ow 225 and 300 Watt
monoblocks, the key being the wonderful EL34l6cA1 tube: people who love that
tube will not settle for any other! This love of certain tube types occurs again
with our807-powered 120 Wan unit: we respect that love, and will not deny the
afficionados.
The biasing is by tube type: the 6550 runs at 35 milliamps standing cur-
rent (350 mV from the test point to ground) while the KT66 and EL34 requires
30 milliamps (300 mV from the test point to ground).
The 100 and 160 Watt "compacts" have the series-parallel style output
transformer with ABCDEFGH under-chassis tags while the 80 Watt version of-
fers 8 ohms (green wire) as standard with a possible change-over to 5 ohms
(green/yellow wire) under thc chassis.
Please note that the output impedance is not a change we envisage to be
performed by the buyer: a trip to the dealer is required. Only in rare cases is
this change desirable in any event; the unit as shipped will drive all loudspeakers
intelligently interfaced power-wise. For the record, the "rare cases" referred to
THE VTL DELUXE MONOBLOCKS 83
above concern ribbon and other known difficult-to-drive loudspeakers which are
actually better served by higher power.
The VTL deLUXE Monoblock Amplifiers
There are several models in this category: the 120, 150,225, and 300 Watt units
in the deluxe range, and the 150 and 350 Watt units in the Manley range. Let
us discuss the '120' first.
The 120 watt unit is unique in that it can be (instantly) switched into pure
Class A triode mode which yields 50 watts ourput instead of 120 watts in the ABI
tetrode mode. The unit employs four type 807 tubes in parallel push-pull. The
807's have their anode outputs in the form of top-mounted caps; we realise that
this feature plus the triode-switching facility make the 120 a somewhat esoteric
specialist amplifier and it is intended so. (However, the 120 is optionally available
with 6L6GC's for those who feel that the anode-capped, romantic-looking 807's
are just loo esoteric! The 6L6GC and the 807 are closely related beam-power
tubes with the 807 being closer yet to the British KT66; so close that the 807 was
chosen by D.T.N. Williamson for the American version of his historic amplifier.
But to our ears, the 807 has no eqtal in its triode configuration.)
Please note that the switchover to triode mode in the 120 must be made
with the power off it is nol intended for zippo-like
- the price of powered-flipover flipping. reducedknow
(But we
you'll try it; remember: is greatly tube
life don't say we didn't you!) The fbur triode/tetrode roggle-switches are
- on the top front edgetell the amplifier nominally in front of their respective
located of
tubes. With these four switches pointing ro the tubes the amplifier is set Trrnoon;
switching them away (forward) from the tubes engages the Tnrooe mode.
You might wish to hear the "Tri-Tet" mode also; this legitimate configura-
tion operates with each half of the push-pull phase having a triode combined with
a tetrode and produces about 75 watts output. In this mode the amplifier will stay
in Class A up to about 25 watts; to select the "Tri-Tef' status the extreme right
and ieft silver toggles must be left in the tetrode (facing rearward) position and
the other two pulled to the triode, or forward-facing, position.
Now we come to the fifth switch, which is centrally-mounted in front of
the (smaller) input triode. This switch allows you to decrease the negative feed-
back by 5 dB which a/.ra therefore increases the gain by a similar amount. The
5 dB feedback reduction position is with the central switch facing forward (same
as "a11 triode" position) and is, we feel, of benefit only rr the triode-mode; i.e.,
with all switches engaged/pulled to front. Even so, you will need to be using
an extremely accurate and low-distortion preamplifier because the amplifier will
greatly magnify any traces ofdistortion. And, yes, you can leave the extra 5 dB of
I
feedback (central switch pushed rearward) in the tetrode-position, if you prefer,
I
I
i
I
84 THE VTL BOOK
with no harm done; in this set-up the liquid smoothness of the sound is very
seductive.
Having read thus far, we feel sure you'll understand what we mean by the
terms esoteric and specialist. Our prayer for the utilization of the 1 20 is that
the audiophile who chooses it will know that he/she has ABC sensitive speakers
which require (or only require) xYZ watts and will leave the amplifier set in one
or other of its optimum modes; we hope that the switching facilities will not be
used for party-tricks in tetrode-mode, with reduced feedback, driven to near-clip
on Dire Straits.
There will be those people who will question the intelligence of making subh
an amplifier available at all. Well, the answer is to explain that as a specialist
audio manufacturer we want to offer almost-historical products to the disceming
audiophile (tubophile?) that advance both hisfter knowledge and standard of
musical-reproduction. It saddens us that there were audio products available
thirty years ago that were actually better than some of today's ""breakthroughs"
and moreso how few people know or remember or have heard this to be so'
You will note that on the 120 the protection-bar (please, not "handle")
is mounted directly over the 807 anode-caps: this is intentionally done both to
protect the tubes as well as to make the anode-caps a little difficult to remove.
Please remember that there is over 500 Volts present at these caps, and
therefore they should not be touched with the amplifier on for fear of a
dangerous electrical shock. We recommend that the amplifiers be mounted out
of reach. Better yet, we specifically do not recommend the deLUXE 120 as the
ampliflers of choice for a household which includes children and pets. It is a
specialized unit designed for the informed and careful adult.
The design of all our amplifiers is such that the user should neither be
constantly worrying about nor adjusting the bias voltages; it is only when con-
templating the installation of a full set of new output tubes, which may be of a
very different quality of manufacture, that the amplifier will need need to be fully
re-biased. The biasing procedure should only be attempted by trained personnel-
The method of bias measurement, similar to that used in all our power
amplifiers, differs only in that the the 5-pin 807 tube connections are totally
dissimilar to the standard octal. (Pin 4 is the cathode for the 807; pins 1 and 8
for the octal-base in our equipment. The bias is set by measuring 260 mV DC
at the cathode end of the cathode resistor and ground (or 0 volts)' This converts
to 26 mA of DC current being drawn in the quiescent state. Newer builds of
the 120 have their bias test points along the front edge of the chassis, which is
common to all deLUXE monoblocks. Other differences in the 120 are the 6 Volt
DC rail lbr the heaters of all tubes, including especially the output 807's; DC on
the heaters is mandatory to enable this mysticaì tube to perform its best.
THE VTL DELUXE MONOBLOCKS 85
The output transformer is set for 5,5 ohms, and we suggest and request that
this be left so; the unit already has a two-position feedback switch (providing a
5 dB range) and, within the power constraints of the 807's particularly when in
the triode position, no output impedance alteration is envisaged. As stated, this
is somewhat of a specialist amplifier best suited to very efficient loudspeakers,
commonly found in the triode-fans' systems the JBL and other circa 100 dB
types. -
The VTL 150 Watt unti is very closely related in layout to the 120, and
uses the same 1650 microfarad double-blank capacity network common to all
deLUXE monoblocks, as well as the dedicated power supply (including a separate
transformer) for the critical input tube. In the Manley version (cosmetics aside)
which relate to front-panel access of bias-check and, importantly, the ability ro
select feedback in 2,5 dB steps and to optimise the feedback 'slope' capacitor
for different loudspeakers. The 150 Watt units have four 6550A's as output tubes,
and have multiple secondary output transformers (commonly set for 5 ohms).
The VTL225 and 300 wafi deLUXE monoblocks are closely related to each
other, differing only in their output tubes and transformer type. The 225 uses
EL3416CA7's, while the 300 watt uses 6550A's; both models use eight rubes per
chassis. We used to consider the 225 a special-order unit but, as with the 120,
there has been so much groundswell demand that we now routinely produce this
model. Arthur Pfefler of The Absolute Sound is very fond of his 225's, and
the amplifier seems to be supremely suited to the excellent Martin Logan CLS
electrostatics; again, it is the use of the EL34 that seems to be highly desirable to
some folks.
The VTL 300 and 350 Manley deLUXE monoblocks conrinue to amaze
us in their never-slacking rate of demand and back-order; we realise that this is
due to their extraordinary sound, power, reliability relative to price ... easily able
to withstand industrial use in control rooms, these big fellows run cool and just
work, work, work.
'In the Manle! 350 watt version
we offer the increase in power (which
comes about via the additional dedicated supply for the driver and a slightly higher
rail) plus the feedback and 'slope' variability as mentioned in the preceding 150
section. The output transformers are configured for 5 ohms and are of the multiple
secondary type, easily reset to other impedances in an authorised workshop. The
bias test points and adjustment set is accessible from the top of the units, as are
the test points for measuring equal AC drive-input voltage to eachof the push-pull
output phases.
86 THE VTL BOOK
The 500 Watt and 1000 Watt Monoblocks
The 1000 waff Manley monoblock has recently joined the 500 watt VTL and
Manley monoblocks. These power-houses are also dual-chassis (per channel)
and are closesly related in topology to each other and the 300 watt units in that
they are 6550A-powered and are fully ultra-linear. The 500 was clearly inspired
by Harry Pearson, while the 1000 watt unit owes its 'birth' to the master cutting
room.
The 'birth' of our 500 Watt Monoblock has a human-interest (well, audio-
human anyway) story that we feel is worth the telling. We were at the conceptual
stage of design pre-thinking in power terrns. We wondered whether there was a
market desire for a 'super-power' tube amplifier (bearing especially in mind the
large quasi-ribbon speakers), rather like the 1000 watt units we have custom-built
for driving cutter-heads.
At precisely the same time, that master reviewer and standard-setting critic,
Harry Pearson, was apparently pondering whether anybody else felt such a need
existed, or whether anybody was interested enough and, indeed, capable of de-
signing such a piece. In a phone conversation with Mr. Pearson's right-hand man,
Frank Doris, the technical director of "The Absolute Sound", we voiced this mus-
ing of ours. After a perceptible silence, Frank said: "How extraordinary, for that
is what HP has been contemplating exactly; I was going to bring that up next!"
And so the '500' came into being. As a matter of interest for those readers
outside of the USA, can you see in the reporting of the above event how important
Harry Pearson's constructive criticism and creative suggestions have been to the
whole picture of High End audio? For he has steered many designers, besides
ourselves, into radically improving or totally initiating worthwhile products. We
thought you ought to know that we respect and are grateful for this kind of input
enthusiasm.
Besides its huge 500 watt power, derived from two six-pack (hexagon) pairs
of 6550's in push-pull parallel ultra-linear configuration, the immediately obvious
difference between the '500' and any of our other "deLUXE" monoblocks is
that the '500', like the lchiban, is built on two chasses per monoblock. The
amplifier is built on one, and the power supply on the other. They are interlinked
by a fat umbilical cord. Separating the power units from the amplifier has other
important benefits apart from making them both 'workbench-negotiable' and easy
to transport.
The idea goes all the way back to the early American Mclntosh, Brooks and
Western Electric units of the late thirties and forties: this is also how Mr. William-
son first presented his amplifier. It is Nth degree thinking; the desire for design
without compromise. The EMI fields of magnetism do radiate to the tubes to
some extent; more importantly, the minute vibrations mechanically generated by
THE ICHIBAN MONOBLOCKS 87
large transformers (and we're talking 2 kVA here) do permeate to some extent,
no matter how well they're built.
Further, like the lchiban, the '500' has on its separate power unit dedicated
supplies for the full input circuitry, thereby leaving the main monster power
transformer to cater for the output stage's needs exclusively. The other signilìcant
difference is in the driver-stage, wherein paralleled 128H7 triodes each drive half
the push-pull phase; that's live watts of audio power driving of each side of the
output section, by the way.
Because of the number of output tubes in the '500', we have made bias-
measuring easily accessible with standard resistor colour-coded 'tip-jacks' ap-
pearing in front of the tubes; as with other models the bias is not worrisome, and
is set for a cool-running 30 milliamps quiescent current.
The lchiban Pure Class A Triode Monoblocks
What? Why? Who? When? Wher:? are the usual preceding words to questions
about this inscrutable unit of ours. First, 'what' it means (in Japanese) is "Number
One". We refer to that in the sense of importance, for it is the (now) antique
triode that set, and itill sets, the the historical and current stanclard of audio
amplifier excellence. In simple language, triodes will always blow any other
form of amplifier far, far away (within their power capability, obviously). And
thercby cornes that efficiency thing again, for triodes certainly are outstandingly
ineffìcient. In pure Class A this is even moreso, where efficiency is deemed to
include heat, siz.e, weight and cost. Besides the triodes' need for high anode
voltage (for reasonable power) and high current for their filaments/heaters, they
have very little gain or amplification-factor (as low as 2 x) and are notoriously
hard to drive. Commonly, in bygone times, they needed inter-stage transformers
to help overcome this problem. In 'triode-mania' territories the use of a tetrode
strapped as a triode is termed 'pseudo-triode' , but we don't agree this should be
applied to the EL34 for the reason that a very select number of tube types, and
the EL34 is such an example, were specifically designed with triode-configuration
strongly in mind the 807 is another, by the way.
-
The double-chassis VTL and Manley versions of the lchibafl both are
supplied with rare South American redwood side-members. The Manley version
has large milled panels which house the variable feedback and slope controls, and
bias testing facilities. Other than thar, there are no differences between the VTL
and Manley versions; this is because the lchiban, like the 500 and 1000 watt
units, inherently have dedicated split power supplies for input and driver stages.
We use two Class A paralleled resistance-coupled triodes (what else!) sections
in the lchiban and in most other respects it is similar in topology to the '500'
described elsewhere. In its standardly-delivered build, the lchiban utilises twelve
88 THE VTL BOOK
EL34l6CA7's configured in triode mode. Its 200 watts of output power make it the
world's most powerful Class A amplifier in standard production. The Ichiban is
another case of something we thought might be only of interest to a select group
that tumed out to be popular enough to warrant keeping it in standard production
though with some lead-time which we are constantly trying to reduce.
- Elsewhere you have read our views on what smaller triode amplifiers can
do for music; we leave it to your imagination what rftis size of Class A triodes
can do modesty precludes our repeating all comments from lchiban owners.
-
Here is just one portion of a letter from a very disceming musicologisthwner,
Herman Ng:
The most arresting impression from these triode amplifiers was their ability
to reproduce the natural tonal qualities of the musical instruments, as well as the
harmonic decay within the particular hall regardless of the playback volume. This
goes for solo instruments, as well as the harmonic decay within the particular hall
as well as full comples symphonic music. Because of the faithful reproduction
(tonal and harmonically accurate frequency response) the illusionary sound curtain
is so real that it borders on the ,flreal.
Thank you, Mr. Ng; we could not have put it better ourselves.
The people who will settle for triodes only, (this is the 'where' and 'why'
part) are a select band of audiophiles who use very efficient loudspeakers (a
necessary counter-balance) and are found in the woodwork of Europe and Japan.
Eschewing sub-woofers and megabuck-megaspeakers, they 'trip' on triodes, often
as low as four and five watts worth, and will brook no argument about their pref-
erence. The lChiban with its 200 watts assumes the output status of broadcasting
and power-stations to them. Are they wrong in their audio thinking? No, not at
all. Nobody is wrong in their desire to listen to their studied preferences, in our
view. If we played you some Klipschoms being driven by gossamer-smooth tri-
ode amplifiers, you would probably be very agreeably surprised. Shaken, maybe.
You might even want to own some.
You don't believe this is possible? Your favourite audio-dealer does not
keep Klipschorns? We knew that. You find it very hard to swallow that older
technology can be good technology? Possibly even better technology? Don't bet
big on it. Doug Sax and Lincoln Mayorga of Sheflìeld Recordings went through
the same painstaking process of sifting through older equipment and methods
that had been steam-rollered by the great big truck sign-written 'NEW!' and re