Pass Labs XA60.5 User's Manual
Contents
1. 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 12 For your protection please read the following XA60 5 Owner s Manual Water and moisture Electrical devices should not be used near water as per example near a bathtub washbasin kitchen sink laundry tub wet basement or swimming pool Care should be taken such that objects do not have the opportunity to fall and that liquid is never spilled onto or into the device enclosure through openings Power Sources An electrical device must be connected to a mains power source in strict accordance with the supplied product ownet s manual Please verify that the AC mains voltage specified in the product manual matches those requirements indicated on the unit and the AC voltage provided to your location by the power company Grounding Adequate precautions should be taken so that the grounding provisions built into an electrical product are never defeated Power Cords Pass Laboratories provides a power supply cord that meets all legislated requirements for the market in which the product was originally sold If you choose to substitute an after market product we urge you to choose one that is fully safety rated by the necessary local authotity Power Cord Protection Power supply cords should be routed so that they are not likely to b2. are electrically live neither is grounded and should not be treated as ground This is particularly important if you are using the output of the amp to also drive a subwoofer amplifier or other active component If there is any question please contact the manufacturers of the products involved both they and we will be happy to advise you If you happen to need a clean signal ground connection for any reason we provide a dedicated 5 way binding post just for that on the rear of the amplifier On the rear panel you will also find a pair of 5 way binding posts for external turn on control Applying 5 to 12 volts DC at this connection will override the front panel stand by switch and turn the amplifier on XA60 5 Owner s Manual So the amplifier is sitting there unconnected Make sure that the rear panel power switch breaker is off down Plug the AC cord into the back of the amplifier and then into the wall Then turn the power switch breaker on up The lights in your house will dim for a moment as the power supply charges the capacitors If your amplifier uses a circuit breaker and not a fuse please note that this circuit breaker is not a safety device or emergency disconnect for this product It will provide current limiting which will protect the amplifier but it does not provide personal shock protection in the manner of a ground fault interrupter One more reason why it is important not to defeat the Earth
3. channel amplifiers with half the output power per channel of comparable mono amplifiers and Class A amplifiers with half the output of Class AB amplifiers The X amplifiers deliver more output power per dollar and the XA amplifiers have a better subjective performance All of the amplifiers drive known loudspeaker loads without misbehaving and all are unconditionally stable into low impedance and reactive loads XA60 5 Owner s Manual All the usual performance metrics power distortion noise input impedance damping factor and bandwidth have all been improved in this latest generation The power supplies are larger with fast rectifiers gating to larger capacitor banks The increases in AC line noise worldwide have been addressed with heavier EMI filtering and dramatically quieter power transformers In addition through improved biasing regulation the circuits give much more consistent performance under varying AC line voltages and over a variety of ambient temperatures All this is very nice but only if it improves your listening experience We listen very carefully and critically to our amplifiers with a wide variety of associated equipment and we take our time with it Musical performance is most important and is the basis of our success over the years It s true that we also value the other things The design and manufacturing decisions have to balance subjective performance against reliability cost specs and ego in app
4. connection of your power cord On the front panel the Standby LED indicator should be glowing blue indicating that AC power is available and the capacitor banks are charged If the Power LEDs are lighting the meter use the front panel stand by button to go to stand by mode Now turn off the rear power switch and unplug the AC power cord from the wall while you connect the speakers and inputs Check to make certain that the loudspeaker cables aren t shorted at the loudspeaker end connect speaker cables to the output binding posts on the amplifiers observing correct polarity The output binding posts will accept either bare wire or spades Regulatory agencies in many countries have banned binding posts that will accept a banana plug forcing us to abandon this option Make sure that your speaker wires only attach to the outputs of the amplifier not to each other and never to the amplifier case Remember the warning about treating the output connections as ground particularly if you are using a powered subwoofer with this amplifier If you need a ground use the one provided specifically on the rear panel of the amplifier The amplifier may be driven single end or balanced your choice Single ended input will always occur through the RCA connector and balanced input will always occur through the XLR connector Again if you drive the amplifier single ended then leave the supplied jumpers in place between pins 1 amp 3 o
5. factory or a factory specified repair facility Non North American customers should consult with their original Pass Labs dealer or distributor for warranty repair instruction prior to contacting the factory or shipping product 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 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 information Any modifications to Pass Laboratories products that have not received written factory approval nullify all claims and void the warranty 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 its 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 suspected as counterfeit product Pass Laboratories will not repair or in any way indemnify any counterfeit or cloned product
6. some flexibility in choosing source interconnects without shields though shields ate usually a very good idea For long runs balanced cables ate highly recommended for their inherent rejection of noise We prefer speaker cables that are short and stout Oxygen free copper and silver are the suggested materials If you find any really exceptional cable made of gold please gift us a couple hundred feet Fortunately this amplifier is not sensitive to the capacitive inductive character of some of the specialty speaker cables so feel free to experiment We have found that about 90 per cent of bad sounding cables are really bad sounding connections and we recommend that attention be paid to cleanliness of electrical contact surfaces and proper connector fit Speaker cables should be firmly tightened down at the speaker output terminals but not with a wrench Output terminals will not withstand the levels of torque that may be easily applied by wrench Hand tightening without excessive force is plenty Cleaning contact surfaces with one of the commercially available electronic contact cleaners should be part of your annual system maintenance Product Life So how long will this hardware last It is our experience that barring abuse or the odd failure of a component the first things to go will be the power supply capacitors and from experience they will last 15 to 30 years Fortunately they die gracefully and are easily replaced by a good
7. technician After that the longevity will depend upon the number of operating XA60 5 Owner s Manual thermal cycles but we can say that we have had amplifiers operating in the field in excess of 20 years with no particular mortality and we don t have good information beyond that More to the point you should not worry about it This is a conservatively built industrial design not a frail tube circuit run on the brink of catastrophic failure If it breaks we will simply get it fixed so sleep well Pass Laboratories PO Box 219 24449 Foresthill Rd Foresthill CA 95631 USA www passlabs com sales passlabs co service passlabas co tel 530 367 3690 fax 530 367 2193 PAYS Pass Pass Labs Pass Laboratories Aleph and Zen and are all registered trademarks of Pass Laboratories Inc and all rights thereto are protected by law Supersymmetery 10 XA60 5 Owner s Manual 11 XA60 5 Owner s Manual 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 parts and labor charges incurred at the repair facility Consequential damages are specifically not covered and damage due to modification or physical abuse is also not covered The customer assumes responsibility for shipping and insurance to and from the
8. PASS XA60 5 Owner s Manual May 17 2007 1 XA60 5 Owner s Manual Nelson Pass has been designing audio electronics since about 1971 first with ESS remember Heil transformers and then forming a new company Threshold in 1975 Threshold pioneered the design of high power Class A power amplifiers and later high power amplifiers using only local feedback the Stasis series Pass sold Threshold and created Pass Laboratories in 1991 where he concentrated first on elevating single ended Class A power amplifiers to new power levels and performance the Aleph series Along the way he found the time to design successful lines of amplifiers for such companies as Adcom and Nakamichi and has contributed approximately 60 designs so far to the public Do It Yourself hobbyist community Over the years Nelson Pass has made power simplicity and performance his design signature The hardware tends to run heavy and hot but elicits high performance and reliability from simple circuits with little or no negative feedback In 1998 Pass Labs released the X series of audio power amplifiers based on the SuperSymmetric topology U S Patent 5 376 899 which elicits high power and performance from simple circuits with minimal feedback The first X amplifier the X1000 was intended as the premier example of the power of this principle delivering 1000 watts rms into 8 ohms at low distortion By itself of cours
9. e this is no miracle but you have to consider that products with comparable performance have complicated circuits with as many as nine consecutive gain stages and lots and lots of negative feedback The X1000 had only two stages and used only local feedback The difference was the unique balanced circuit topology in which circuit errors are replicated at both output terminals so as to cancel and disappear across the loudspeaker terminals The high quality of the sound reflects both the low distortion and simplicity of the gain path The SuperSymmetric circuit consists of two identical matched circuits arranged like the wings of a butterfly showing symmetry from left to right and operating balanced to the loudspeaker The amplified signal appears with opposing phase across the loudspeaker Most of the distortion and noise appears in phase across the loudspeaker and is not seen XA60 5 Owner s Manual We start with simple FET circuits already having low distortion and noise and arrange them in two symmetrical halves The two halves of the amplifier channel are closely matched eliminating a large portion of distortion and noise without feedback A small amount of feedback is also applied not so much for the purpose of reducing distortion but to make the distortion as identical as possible on both polarities of the balanced output It is easier to make distortions more identical than to remove them with feedback and this is the operati
10. e walked on abraded or pinched by items placed on or against them paying particular attention to cords where they enter plugs or exit from a device Never under any circumstance insert a cut or damaged power cord into a mains power socket Power and Signal Cables should never be connected disconnected with equipment powered up Failure to heed this warning may damage or destroy equipment Ventilation Power amplifiers run hot but you should be able to place your hands on them without discomfort You must allow for this heat in installation by providing for free air circulation around the product Electronics should not be subjected to sources of excessive radiant heat Excessive heat can shorten the life of the product and may cause the electronics to self protect and shut down Servicing To reduce the risk of fire electrical shock or other injuries the user should not attempt to service the device beyond that which is described in the operating instructions All other servicing must be referred to qualified service personnel 13
11. icated on the rear panel It will be either 230 volts 115 volts or 100 volts The larger amplifiers have a circuit breaker of the appropriate capacity The smaller power amplifiers use a slow blow 3AG type fuse The frequency rating of the AC line source is 50 to 60 Hz Please verify that the amplifiers indicated voltage requirements are consistent with the supplied voltage and current at your location On the rear panel you will find both RCA and XLR type input connections for single ended or balanced inputs If you use the RCA input be certain that the XLR connector has a gold shorting plug between pins 1 and 3 which connects the minus input to ground otherwise the amplifier will not operate properly If you lose this plug just contact the factory we give them away all the time The question comes up all the time are balanced inputs XLR better than single ended RCA The answer is that balanced lines generally give lower noise and slightly less distortion They are recommended unless your favorite source component has only RCA outputs Also on the rear panel are the output connections for the loudspeakers On stereo amplifiers there is one pair per channel and on mono amplifiers we provide two pairs wired in parallel to facilitate bi wiring a loudspeaker As you are probably familiar the red one is positive polarity and the black one is negative Please note that being a balanced output both of these terminals
12. n the input XLR On the XLR connector pin 1 is ground pin two is positive input and pin 3 is inverted negative input Pin numbers are marked on the XA60 5 Owner s Manual XLR If you re install the jumper incorrectly or leave it lying about the amplifier will not work properly and you will be able to tell Choose either XLR or RCA inputs If you run both at once from different components the sound is not likely to be optimal but it shouldn t cause damage anywhere Now that the source component is connected turn the volume all the way down Plug the power cord back into the wall and turn on the rear power switch Push the front panel button to activate the amplifier The lights will come on You are ready to play music With any luck you can now enter that blissful state and we won t expect you back for a while It s always possible that something may go wrong If so don t get excited We know It s really aggravating when a product doesn t work but it will get fixed and often it s something really simple We go to a lot of trouble to make products reliable and the failure rate of our amplifiers is very low This is small comfort to the few but take it easy and give us a call if you have problems People are interested in how long it takes for these amplifiers to break in Depending on the resolution of the rest of your audio chain you may or may not notice any break in of the amplifier beyond the first fe
13. ng principle of X amplifiers Since the X1000 Pass Labs products have continuously evolved toward higher performance The Class AB X series was joined by the Class A XA amplifiers Subsequent improvements to the Class AB X amplifiers resulted in the X 5 products and their phenomenal success has led to the Class A XA 5 series As always the goal has been the best musical and objective performance possible with minimal parts in the signal path and minimal feedback This process is not completely understood and many of the improvements are the result of trial and error and extensive listening Measurement of performance is important to us and we feel that well designed product sounds good and measures good Apparently it is possible to make an amplifier which measures well but which does not please the ears and so we let our ears be the final judge X 5 and XA 5 amplifiers utilize the same basic circuit topology and gain devices They differ in the sizes of the power supplies the chassis and heat sinks and the number of output devices The output stages of the X 5 series are operated in heavily biased Class AB with an idling dissipation similar to the rated output The XA amplifiers operate pure Class A with idling dissipation more than twice the rated output Within any given chassis size the X and XA amplifiers are designed to dissipate about the same power and it is not surprising that this leads to two
14. roximately that order That is why we make more than one amplifier but all are built with the same commitment to quality If you have purchased this amplifier we thank you for your confidence and hope that you enjoy it for many years If you have any questions or comments or if we can help you with your audio system pelase don t hesitate to contact us service passlabs co passlabs co Tel 530 367 3690 Fax 530 367 2193 Pass Labs PO Box 219 24449 Foresthill Rd Foresthill CA 95631 XA60 5 Owner s Manual SET UP X amplifiers run at about the same power as their output rating and XA amplifier run more than twice that The heat sinks on the side of the amplifier run hot to the touch about 25 to 30 degrees C above ambient so you can expect 50 to 55 degrees C temperatures on the heat sinks It is very important to the long life of the amplifier that they get good ventilation You can put this amplifier anywhere you want but it must have good ventilation Do not place it in enclosed cabinets or small closets without means for air to circulate freely Stacking these power amplifiers directly upon cach other is not recommended for the same reason You should have a minimum of about 6 inches clearance to the top and sides for adequate air circulation When not actually intending to play music the amplifier should be left in standby mode where it draws only a few watts of bias on the output stage If you wish
15. to reduce the power draw to 0 you can shut the amplifier off via the rear panel switch however we recommend that for minimum noise this switch should be toggled in stand by mode We have provided a standard IEC power cord that fits into the standard 15 amp IEC receptacle at the rear of the amplifier chassis With the exception of the largest of the X and XA series there is no difficulty running two amplifiers on a single 15 amp circuit Given the high current draw we generally do not recommend active line conditioners although they are unlikely to damage the amplifier This amplifier is equipped for operation with an earth ground provided by the users AC outlet Never defeat this ground connection The signal ground of this amplifier is connected to earth through a power thermistor which provides a safety ground but provides isolation from system ground loops For maximum safety we suggest that the power cord should be the last cable installed on your power amplifier You may if you wish substitute a 15 amp aftermarket power cord for the one we have supplied Only use power cords which meet all local safety standards and carry acceptance marks from the local regulatory authority The power cord should be attached to the amplifier prior to plugging into house power Place the rear mounted switch in the off down position before plugging in this amplifier XA60 5 Owner s Manual The amplifier s voltage and current rating are ind
16. w hours of operation You will very likely notice the difference in sonic character between cold and normal operating temperature over the first hour so we recommend letting these amplifiers warm up before any serious listening This generation of amplifiers warms up faster and is more bias stable during warm up than previous versions but we still recommend an hour for critical listening At the factory we adjust the bias and offset values initially and then after warm up and then again after 48 hours If necessary The sweet spot is a sink temperature between 50 and 55 degrees C but this is not critical and will vary with your room temperature You should be able to put your hands on the heat sinks without undue discomfort for 5 seconds or so The amplifier has a thermal cutout that will disconnect AC power if the temperature exceeds 75 degrees Centigrade This thermal cutout XA60 5 Owner s Manual should never occur in real life This is a very rare occurrence and would indicate a serious problem Interconnects and Speaker Cables We have a general recommendation about interconnects and speaker cables They should cost less than the amplifier and contain at least some conductive material We have tried a lot of products and most work well but as a practical matter we cannot make blanket recommendations The amplifier is not sensitive to source interconnects It is also not sensitive to radio frequency pickup which allows
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