The conrad johnson LP66S vs. a modern ST70 kit
mebrat...@yahoo.com
more or less a Dyna Stereo 70 done 'right', though to be exact here,
it is somewhat heavier and must use heavier output transformers than
the ST70, which in reality is a 40 wpc amplifier from a output stage
standpoint (its inadequate power supply limits things to 35 wpc by
spec and about 28 in reality with bogey line voltages and an average
rectifier tube in place). In reality it's almost an exact analog for
an amplifier I built in or around 2001 with a pair of McIntosh MA230
output transformers and a power transformer from a Fender Super Twin
Reverb. I had about $400 in that amplifier and it was all new parts
except for some hamfest ceramic tube sockets and the chassis which was
a recycled telephone B-box cover I had a friend cut down and turn into
a chassis and base plate. It was every bit as attractive as the basic
c-j chassis when completed, save for the heavy faceplate.
The ST70 kits now available are in the $400 to $800 range. Again,
admittedly not a direct comparison, but what makes the c-j worth five
to ten times as much? it certainly, very certainly isn't sound. While
the original factory ST70 was a shitbox, the current ones do have many
if not most of thet unit's original problems fixed. They do have a
more substantial power transformer with a secondary to accomodate the
average voltage levels found in most homes in North America today, and
they do feature at least a circuit board made of good modern
materials, and most have at least some improvements to the original
highly flawed front end-or they offer you the option to simply use any
of a dozen aftermarket boards, none of which are as out-and-out fucked
up as the original.
c-j (I find it dificult to not capitalize here, but that's how they
want it) offer a halfway decent amplifier at a quite high price, but
they are not selling an amplifier so much as consumer confidence. When
you buy c-j, ARC, or Manley/VTL today you are buying approval from
snooty people with no electronics knowledge whatever who duffer no
shame for the loss. They are not interested in sound, or electronics,
or even "Tone" or "MUUUUUUUUUUUUSSSICCCC". They are after yuppie
affirmation. In not so many words, they want everyone to think they
have a big pecker.
The c-j website lists the weight of this unit at 45 lbs. I suppose
this does not include the attachnemt so one may, like Mr. Lifto, use
it for its real purpose.
LP66S Vacuum-Tube Amplifier
Consistent with conrad-johnson's design philosophy that circuits
should be kept as simple as possible, the LP66S works its magic with
just seven vacuum tubes. A composite triode input stage is direct
coupled to a cathode-coupled phase inverter – the same improved wide-
bandwidth driver stage found in our other, more costly LP amplifiers.
The output stage is comprised of a pair of 6550s (each channel)
operated in ultralinear configuration for an optimal combination of
high power and low distortion. Limited negative feedback is applied to
the circuit to reduce distortion and provide a sufficiently high
damping factor to control most real-world speaker systems. Discrete dc
power supply regulators are provided for the input and inverter
stages, in order to isolate each stage from the output signal.
As with all conrad-johnson tube amplifiers, the LP66S requires no
complicated adjustments or specialized equipment to maintain. To
assure continued peak performance, the owner need only make a simple
bias adjustment when new tubes are installed. Built in LED bias
indicators allow the user to make this adjustment using only the
supplied screwdriver.
Component parts quality is a signature strength of any conrad-johnson
product. Audio circuit and related power supplies feature precision
metal film resistors and high-performance polypropylene capacitors.
There are no electrolytic capacitors in the audio circuits or in the
related power supplies. Proprietary wide-bandwidth output transformers
contribute to excellent high frequency performance. Even the input/
output connectors and internal wiring have been carefully selected for
optimal sonic performance.
Conservatively rated at 60 watts per channel, the LP66S offers
sufficient power for most applications. Users who have not previously
experienced the dynamic range and lifelike timbre of tubed components
will find the LP66S an ideal introduction to the joys of modern tubed
amplifiers. Along with its tonal integrity, its ease of use, low
maintenance costs, and reliability will be a revelation for those who
have only experienced "entry-level" tube gear. For veteran
audiophiles, its modest price and size make it a great choice for
bringing conrad-johnson quality to a "second” system. A word of
warning if you are in this last group: whether in the den, library, or
bedroom, the LP66S’ wide bandwidth and low distortion will give your
main system a run for the money.
We invite you to visit conrad-johnson dealer to audition an LP66S and
perhaps rekindle your passion for enjoying great music in your home.
Specifications
Power:
LP66S - 60 watts per channel from 30 Hz to 15 KHz at no more than 1.5
% THD or IMD, both channels driven into 4 ohms (also available
connected for 8 or 16 ohm loads)
Sensitivity: 0.5 V to rated power
Frequency Response (at 10 watts): 20 Hz to 20 kHz, +/- .25 dB
Hum and Noise: 102 dB below rated power
Input Impedance: 100 kOhms
Tube Complement: 3 x 6922, 4 x 6550
Dimensions: 16D x 19W x 6.38H inches
Weight: 45 Lbs.
http://www.conradjohnson.com/It_just_sounds_right/lp66s.html
(Because the reviewer, some incompetent named Marc Phillips, included
not even the basic details in his so-called review, one must search
for the relevant basic numbers. Fortunately, your diligent scrivener
has found the essential data and includes it herewith. )