News
Welcome to the new Reno Hi-Fi
website. Thank you for your patience as we continue to build the website and add
exciting new content. The site will be updated periodically
with postings about new
products and developments at Pass Labs and First Watt. There will be much more
information forthcoming so the site can be a helpful resource and answer
frequently asked questions. Your comments and suggestions are welcomed at:
mark@renohifi.com.
Pass Labs XP-30 in Production
- Pass Labs new flagship, three-chassis, ultimate, high-end, audiophile
preamp is now in production. The XP-30 features “slave” outputs and level
controls to make bi-amping or controlling a sub-woofer easy. The sound is
incredibly revealing while at the same time being smooth. And that’s just the
beginning. The blacks are blacker in the sound, imaging is fantastic, and top
and bottom are extended with amazing refinement and control. The XP-30 produces
a life-like emotional connection to the music with artful dynamics and warmth.
Here’s how current owners of the XP-30 describe it:
“A game changer!”
“I didn’t know a preamp could make this much difference.”
“Absolutely the best preamp I’ve ever heard!”
Trade-in’s are welcome, and Reno Hi-Fi
will facilitate a head-to-head comparison between a new PASS preamp and your
present preamp. Please ask for details.
The brand new XP-30 product literature is here:
http://www.passlabs.com/xp30.htm
First Watt News - The much
anticipated First Watt SIT/ Static Induction Transistor amps will be
available in early January. The S-2 is a stereo amp with 10 WPC will list
for $5000. The S-1 monoblocks are 10 WPC with control knob and meter for a
list price of $10,000 a pair. A short but extremely exciting 6moons article
is here:
http://www.6moons.com/audioreviews/firstwatt12/1.html
As of the moment, there is no other information about First Watt SIT amps,
but more information will be released when the amps are in regular
production.
Pass Labs Monster Concept Amps to be Released
March 2012 - Nelson Pass,
Wayne Colburn and the Pass Labs crew are now putting the final touches on the
greatly anticipated Pass Labs four-chassis, MONSTER, pure class A,
extremely-low-negative-feedback, concept amps to be called the “Xs” series. Reno Hi-Fi
will be keeping the less-large of the two models in stock. The largest amps will
be available by special order, and everything from Reno Hi-Fi is always
Satisfaction Guaranteed with an in-home demo. Pass Labs list price for the
Xs-150 is $65,000 a pair, and the Xs-300 is $85,000 a pair. Reno Hi-Fi makes every effort to
provide very generous trade-in allowances. Please ask for a quote. The
information paper below contains more details about the Xs line.
Pass Labs Information Paper about the Exciting New Xs Amplifiers:
Oct 17, 2011
Introduction
It seems like only
yesterday. Surprisingly the Pass Labs SuperSymmetry design is 18 years old. In
the last few years we have embraced the fact that designs must move forward;
there are still improvements to be made in amplifiers. SuperSymmetry serves as a
good start, but plus ultra, certainly there is more beyond. Nelson calls
his new amplifier designs Xs. The first piece shipping is
the Xs-300, 300 watt mono-blocks.
Excellence is a virtue, but
it will be sound that determines the long-term success of a design after
the novelty wears off. The audio marketplace is littered with products that
measured spectacularly well but failed to become “classics” because they lacked
the subjective qualities that kept listeners happy beyond the initial
excitement.
With this in mind we set out
to create a new generation of amplifiers that measure well, in a manner which
serves the subjective perception of listeners. Oscilloscopes and distortion
analyzers are excellent tools, but unsatisfactory customers. Real customers care
most about the experience they receive when they sit down and listen to music.
The Role of Distortion
Numbers
A simple survey of
successful audio products shows that distortion numbers by themselves are not
that important. Obviously there is some level at which harmonic distortion is
subjectively intrusive – we could probably stipulate that 10% distortion is too
much, and would probably accept that 1% would be quite audible.
We accept that distortion
becomes inaudible below some arbitrary level. Inaudible at 0.1%? 0.01%?
0.001%? We actually don't know, because there has to be a much larger context
of performance to which a single test only alludes.
Objective measurements are
helpful, and they certainly are important to insure conformity in the
manufacturing process, but once a product is delivered to the customer, these
measurements only serve the customer's listening experience, which is primarily
subjective.
Which is to say that at the
moment a customer listens, all objective measurements become subjective
perceptions. All objective characteristics of the amplifier at that moment
become subservient to the customer's subjective experience.
The Process
We began with a group of
listeners and upgraded the uniformity of their playback systems with components
chosen for the ability to reveal subtle differences between amplifiers.
We built modular amplifier
prototypes, which allowed us to alter any given part of the amplifier – the
heaviest parts, the heat sinks and transformers and such, stayed relatively
static so that one person could easily make major changes, in situ
At the same time we began an
examination of the characteristics and sound of gain devices; tubes, SITs) and
conventional / alternative versions of the FETs which comprise our current
products.
The process took three
years: The first year we settled the power supply and physical package. The
second year we finalized the output stage and front end. The third year we
refined the front end and biasing of the output stage.
Harmonic Structure
We paid careful attention to
the harmonic structure of the amplifier's transfer curve. It is generally agreed
that concentration of this harmonic structure into the second and third
harmonics is best, and the reduction or elimination of higher order harmonics is
desired. What has not been so clear is the best relative second and third
harmonic amplitude and phase.
Emphasis on Output Stage
While every part of the
amplifier is important, playing with developmental tube and SIT designs, we
concluded that it is the character of the power output stage itself which is
most influential in shaping the sound of the amplifier. This is not a radically
new idea – the output stage does the most work, generally has the most
distortion, and is the interface to the complex variable and reactive load which
is a loudspeaker.
In the end, we found that
adjusting the values for push-pull Class A biasing, and also the amount of
single-ended bias in the output stage, gave us a major improvement. Pass Labs
started with single-ended Class A bias in 1991, and current product still uses
some of these techniques, but the new design increases the value of single-ended
bias by an order of magnitude over the XA.5 series of amplifiers. This bias is
supplied by newer, improved constant current sources with tightly regulated
values and high dynamic impedances.
Most importantly, we adjust
this output stage for a particular subjective character. It is helpful that the
output stage transistors have an aggregate capacity well over 10 KW, and that
the massive heat sink assemblies are capable of 2 KW all day long. No cute
little heat sinks here!
The Front End
Initially we designed a new
front end that could be tweaked to produce arbitrary ratios of low order
harmonics. Ultimately we found that it worked better to have the front end
simply complement the output stage in a largely neutral manner.
The new front end is not
complex. It still uses cascoded matched Toshiba Jfets (NOS from our large cache)
for the input devices which drive complementary Mosfets. However we have
increased the heat sinking so that this stage can be biased with 2.5 times more
current and brought in higher quality Toshiba Mosfets (also NOS).
This changes dramatically
increase the linearity and bandwidth of the front end, and with the proper
adjustment of each part of each stage and balancing degeneration with loading
gives us an amplifier front end which by itself has low distortion, a 100 Khz
bandwidth and a fairly low output impedance – all without feedback.
The new front end has a 200
Kohm input impedance (balanced) with very small capacitance. Anything will
drive it.
Feedback is not essential
for this front end, but we have left it with enough open loop gain to allow some
feedback around the output stage. This is strictly in service of the sound of
the output stage, which already specs exceptionally well.
What else would you want
to know about the new power supply?
-
Separate chassis for lower
electromagnetic noise
-
Twice as much storage
capacitance
-
Banks of redundantly
parallel high speed / soft recovery rectifiers
-
Improved high frequency
noise filters
-
Bigger, better transformer
-
Improved passive decoupling
-
Lower standby current
In Conclusion
The new amplifier has a
nicer faceplate designed by Desmond Harrington.
© 2011 Pass Labs
