passTM
SR-1 Owner’s Manual
R1.2 -April 16, 2009
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the driver itself makes non-ideal load for the crossover. To retain
performance comparable to the Rushmore something has to give,
and that something is the overall efficiency of the loudspeaker
system.
First off, the drivers must be intrinsically lower distortion and more
neutral in their character. For this purpose we chose the best pieces
that SEAS has to offer, Nextel coated cones in staggered diameters,
topped off with the Crescendo high frequency dome. The Nextel
coating provides for improved internal damping of the radiating
surface, and we made a point of operating each driver in the “piston
region” below the cone’s modal frequencies. The SEAS drivers
feature long linear excursion, overhung voice coils, and exceptionally
linear magnet assemblies and pole pieces.
These are exceptional drivers, the best we could find, but they
still appreciate being driven by a low impedance source to achieve
the most precise transient quality, the instantaneous “stop-start”
response necessary to impart musical realism. Unfortunately the
very nature of a passive crossover introduces reactive impedances
between the amplifier and drivers, degrading the transient
characteristics and creating lingering artifacts. The result is that the
sonic image is smeared and the little details are obscured.
We experienced these phenomena while comparing various prototype
passive networks against an actively quad-amped version used as a
reference, and the difference was enough to make us choose a brute
force solution – resistively shunting most of the amplifier current
around the driver.
This gives the amplifier a less reactive, lower impedance load. It also
gives the crossover network a less reactive, lower impedance load.
Finally it provides the driver with a less reactive, lower impedance
source.
There is a price to pay for this – instead of a speaker whose audio
band impedance varies from about 8 to 30 ohms, the SR-1 varies
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from 3 to 5.5 ohms. This means that the power amplifier will need
to be able to drive a 3 ohm load (we make amplifiers like that). On
the plus side, the amplifier sees a relatively flat impedance, and much
less of the reactance of the crossover and loudspeaker drivers.
After developing the initial versions of this crossover, we spent the
next two years refining the details of the sound with our five in-
house listeners and their individual environments. We established
the closest “average” desired response, and created adjustments in
mid-bass, midrange, and high end to accommodate a modest range
of room characteristics and taste. The final circuit contains only the
finest components – polypropylene capacitors from Kimber and
Solen, Mills resistors, and high current Erse inductors, all mounted
on thick heavily plated circuit boards. The wire is the same used in
the output stages in Pass amplifiers.
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Unpacking
Caution: These boxes are heavy and require two people using
proper lifting techinques and care when unpacking.
Your SR-1 system comes double boxed with each cabinet in it’s
own double box. Within the double box, each speaker sits in rigid
foam top and bottom trays. We do not suggest that you attempt to
separate inner and outer boxes.
Starting with the two large boxes: Carefully cut the tape securing the
top end-flap on the outer box. Repeat for the inner box. If you
have done this correctly you will now be looking at the bottom of
the speaker, the lower foam tray and a box of hardware containing 4
feet and a jumper cable. Remove and retain the foam tray for future
use.
Once the bottom tray is removed, install the four leveling feet with
the protective washers between the feet and cabinet. The “no-mar”
washers are essential to protect the wood surfaces of the cabinet
from the anodized surface of the leveling feet.
Once the feet are installed, unpack the large (bass) cabinet by tilting
the packing on it’s side first and then titling so the bass cabinet is
resting on it’s feet. At this time lift the outer and inner boxes straight
up and off of the speaker. Retain these boxes as storage containers
for all additional SR-1 packing materials. Remove and retain the
top tray and foam sock. Now place the bass cabinet aas close to the
intended and final location. Once the smaller top cabinet is in place
further movement other than minor positional changes of the large
cabinet will not be convenient.
The top cabinet will be unpacked in a similar fashion. Carefully cut
the tape securing the tops of the outer and inner boxes. Once the
boxes are open you should again be viewing the bottom surface of
the cabinet and a box of hardware.
The smaller top cabinets require that the user install several pieces of
adjustment and dress hardware. All of these pieces will be installed
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with common metric hardware on the underside of the upper
cabinet. The hardware and required tools are supplied with each
cabinet. Please retain the packing materials and supplied tools.
Customer will need to install the “Tilt Bar” and the “Nameplate”
and 3 feet. Like the larger bottom cabinet the feet on the upper
cabinet have “no-mar” washers between the aluminum hardware and
the cabinet finish. To preserve the wood finish on the cabinet, please
install these washers. Once this hardware has been installed you
may invert the smaller box, such that the top cabinet is now setting
upright on a secure surface. Once upright, lift and remove the outer
and inner box, foam top tray and foam sock. You may now place the
top cabinet upon the bass cabinet.
When stacking the small cabinet atop the large cabinet it is suggested
that this be done with the assistance of a second person. One
person should lift the upper cabinet and a second person should
direct and guide the upper cabinet so that the feet of the small
upper cabinet fit directly into the sockets on top of the large cabinet
without damaging the finish on any of the pieces.
The Upper and Lower speaker cabinet each have input connectors
and it is strongly suggested that the customer bi-wire the speakers
with wire of their choice. Speaker wire is a very personal choice,
please discuss cable options with your dealer if you do not already
own cables that you favor. Pass Laboratories has included a set of
jumper cables to allow temporary operation of the speakers with a
single run of speaker cable. Extended listening sessions with SR-1
favor bi-wiring or bi-amping. For those so inclined you are also free
to bi-amp with dedicated amplifiers allowing the freedom to select
separate amplifiers for woofer and tweeter.
On the large, lower cabinets the two pairs of speaker binding posts
are in parallel with one another. When wiring with a single pair of
speaker cables the lower pair are intended for the run back to the
power-amplifier and the upper pair are intended for the jumpers that
will connect the power amplifier supplying the lower cabinet to the
input connectors of the upper cabinet.
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If you are using the preferred method of bi-wiring with two pairs
of speaker cables from the power amplifier, then you may connect
the wire set from the amplifier to either pair of the lower cabinets
binding posts. If you bi-wire the speaker then remove the supplied
jumper wire. In either regard please keep in mind that the speaker
cabinets are polarity sensitive. The positive speaker terminals on
both pairs of speakers need to attach to the positive terminals
of the power-amplifier. The negative speaker terminals on both
pairs of speakers need to attach to the negative terminals of the
amplifier. Maintaining proper signal polarity is critical with all bi-
wired speakers. Failure to maintain consistent polarity between the
speakers and amplifier will be cause all manner of ills from collapsed
and diffuse soundstage to greatly marginalized frequency response.
It is difficult to provide absolute instructions for speaker placement;
but we can give suggestion as to good starting points. Optimal
results with the SR-1 as with most speakers are frequently achieved
with subtle changes of physical location.
Position and adjustment
The first rule however, is that the room in which you listen is perhaps
the most significant of all audio components in the reproduction
chain. Speakers can be made to work satisfactorily in poor sounding
rooms, but it is much easier to achieve success in an acoustically
correct room.
The ideal room is neither overly reflective nor overly absorptive.
In a good sounding room, the absorptive elements tend to be at
reflection points of the sidewalls, floor, ceiling and space behind the
speaker. High ceilings or at least absorptive ceilings lend themselves
to more natural sounding spaces. Diffusion generally is a good thing
and excellent listening rooms typically have diffusion in abundance.
Great sounding rooms are either large enough or absorptive enough
to discourage strong standing waves in the listening area. Good
sounding rooms that present a proper spatial image tend to be very
symmetrical in layout, left to right.
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Under these idyllic room conditions speaker placement is frequently
a simple task. In an idyllic world the speakers would be well out in
the room, typically about 1/3 the distance of the rooms front to
back dimension. The listener would be at mid point in the room
or slightly to the rear of mid-point. The listener and the speakers
would form an equilateral triangle, such that the distance speaker
to speaker would be identical to the distance from either speaker to
listener. The distance from speaker to sidewall would be unequal
to the distance from the speaker to the back wall. To solidify the
acoustic image placement in stereo or multi-channel recordings at the
listening position the speakers will typically be toed in slightly toward
the listening position, rather than square with the rear and sidewalls.
The tweeter height of the speaker will be either at the same height
as the listener’s ear or in some way angled as to achieve equivalent
result. The SR-1 cabinets have adjustable feet, front and rear to
optimize apparent driver height.
Lucky are the very few listeners who have well placed equipment
in a well-engineered dedicated listening space either by design or
happenstance. For the rest of us we have the Pass Laboratories SR-
1. The Pass Laboratories SR-1 Loudspeaker was built to address less
than perfect rooms and less than perfect speaker placement.
Of primary concern was a speaker that would be spectrally balanced
throughout the room rather than only in a very narrow and defined
“sweet spot”. The SR-1 was specifically built to those parameters.
Once the speaker position and upper cabinet tilt is optimized the
listener will need to adjust the level controls for optimal results. In a
symmetrical room, the adjustments for left and right cabinet would
be identical, asymmetrical rooms may require disparate settings of
level controls or left and right speakers. Optimal level settings will be
arrived at only by careful listening to a variety of source material.
On the rear of the SR-1 cabinets are 3 level controls. One level
control on the woofer cabinet and two level controls on the tweeter
/ midrange cabinet. All controls are 3 position switches that select
fixed values. Mid position is considered “Normal”, UP increases the
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level of the drivers associated with a control. DOWN decreases the
level of the drivers associated with a control.
The level control on the woofer module controls the mid-bass level
in the room. This control should be adjusted to optimize bass
in room while minimizing undesirable bloom and boom of low
frequencies.
The two level controls of the upper cabinet are somewhat
unconventional, having been designed to address less than ideal
speaker positions in less than ideal rooms, specifically the average
domestic environment. The upper of the two level switches, selects
one of three tweeter levels. Mid position typically for neutral rooms,
up or counterclockwise for rooms which are otherwise lacking in
high frequency and down or clockwise for rooms which tend to
sound too bright.
The lower of the two level switches adjusts the spectral balance
between the upper cabinet and the lower cabinet. This control
affects both tweeter and midrange drivers equally, raising or lowering
the overall level of the upper cabinet in relation to the lower cabinet.
If the listening room allows the listener to be directly on axis with
the drivers and the room is neutral in character then the most likely
setting of this control will be either the mid position or perhaps
the clockwise or lower position. Rooms that require the listener
to sit off axis to the speakers and rooms that have a surfeit of
absorptive surfaces frequently require this control be in the up or
counterclockwise position. Rooms that sound bright and those with
a multitude of hard reflective surfaces typically require this control
be set in the down or clockwise position.
The suggested settings are just that… suggestions. There is no
substitute for listening and personal judgment. We encourage users
of this product to experiment with level settings and fine movements
of speaker position until the most accurate or pleasant combination
of spectral balance and soundstage are achieved.
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Specifications:
Passive 4-way design, bi-amp enabled
Impedance:
Sensitivity:
3 to 5.5 ohms
86 dB @ 2.83 V @ 1 M
Floor space required: 16.5” X 25”
Overall height:
48”
Bass Cabinet mass:
115 Lbs
Treble Cabinet mass: 40 Lbs
Shipping weight: 400 Lbs / pair
Pass Laboratories
PO Box 219
24449 Foresthill Rd.
Foresthill, CA 95631
“Pass”, “pass”, “Pass Labs”, “Pass Laboratories”, Supersymmetery”,
“Aleph”, and “Zen” and are all registered trademarks of Pass
Laboratories, Inc., and all rights thereto are protected by law.
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How to connect SR-1 to your amplifier using single speaker cable
and short jumper cable.
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How to connect SR-1 to your amplifier for bi-wiring.
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Assembly instructions for upper cabinet
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Please note: Conditions of warranty service and customer rights for
product purchased outside the United States may vary depending upon
the distributor and local laws. Please check with your local distributor for
specific rights and details.
Warranty Information
All Pass Laboratories products purchased new from an authorized Pass
Laboratories dealer in North America are covered by a transferable, limited
3-year warranty. This warranty includes all parts and labor charges incurred
at the factory or factory specified repair facility, exclusive of any subsequent
or consequential damages. Damage due to physical abuse is specifically
excluded under this warranty.
For this warranty to apply the customer is responsible for returning the
product unmodified to the factory within the specified warranty period.
The customer assumes all responsibility for shipping and insurance to
and from the factory or a factory specified repair facility. The conditions
and stipulations of this Pass Laboratories warranty only applies to units
originally sold new through an authorized dealer. Warranty on factory
repair is 60 days and covers only the scope of the original repair.
Non-North America customers should consult with their original Pass Labs
dealer or distributor for warranty repair instruction prior to contacting the
factory or shipping product to the factory for repair. Non-North American
product must be returned to the country of origin for warranty service.
Foreign distributors are only required to offer warranty service on Pass
Laboratories product that they have imported, verifiable by serial number.
Any modifications to Pass Laboratories products that have not received
written factory approval nullify all claims and void all provisions of the
warranty and liability by the maker or authorized distributor. Should a
modified product be returned to the factory for repair the owner will be
required to pay all necessary charges for the repair in addition to those
charges required to return the product to it’s original configuration.
In the case of safety issues, no product shall be returned to the customer
without those safety issues being corrected to the most recent accepted
standards.
Removal or alteration of original Pass Labs serial numbers voids the factory
warranty. Product with altered or missing serial numbers will be suspect as
counterfeit or stolen product. Pass Laboratories will not repair or in any
way indemnify any counterfeit or cloned product. Pass Laboratories does
not offer products in voltages intended for international markets either to
authorized Pass Labs dealers or to third parties located in the United States
or Canada.
For more information please contact: Pass Laboratories Inc.
© 2009 Pass Laboratories Inc..
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