Manley Labs Stereo Amplifier 50 WATT MONOBLOCK AMPLIFIER User Manual

MANLEY  
LABORATORIES, INC.  
OWNER'SMANUAL  
MANLEY 50 WATT  
MONOBLOCK AMPLIFIER  
Manley Laboratories, Inc.  
13880 Magnolia Ave.  
Chino, CA. 91710  
tel: (909) 627-4256  
fax: (909) 628-2482  
 
INTRODUCTION  
THANK YOU!...  
for choosing the Manley 50 Watt Monoblock Amplifiers. Designed around the concept that less is  
more, the Manley 50 Watt Monoblock Amplifiers use only the best available components, with the  
shortest and cleanest signal path possible, and with the use of our own milling equipment we can  
provide you with an amplifier that looks as good as it sounds. We have developed a magnetics  
winding department right here at Manley Labs where we design and wind the audio transformers.  
David Manley has invented a brand new winding technique for the output transformer which exactly  
preserves equality in the push-pull halves of the output stage. This breakthrough has once again put  
Manley Labs on the leading edge.  
Thank you again, and please enjoy!  
GENERAL NOTES  
LOCATION & VENTILATION  
The Manley 50 Watt Monoblock Amplifiers must be installed in a stable location with ample  
ventilation. Allow a minimum of 2 inches of clearance on the top and sides of the amplifier, such  
that a constant flow of air can flow throughout the ventilation openings. We also recommend that  
the amplifier and preamplifier be placed at least 10 inches apart. Do not place amplifiers directly on  
high pile carpet or any other surface that will block the ventilation vents.  
WATER&MOISTURE  
SERVICING  
The user should not attempt to service the amplifier beyond that described in the owner's manual.  
Refer all servicing other than biasing and tube replacement to Manley Laboratories  
SPECIALNOTES  
Tubes may become loose during transit. Straighten and press down each tube before plugging the  
amplifier into the mains socket. Furthermore, NEVER touch the tubes after the amplifier has been  
switched on, the tubes become very hot during operation and should only be handled after the power  
has been turned off and the tubes have cooled.  
WARNING!  
!
TO PREVENT THE RISK OF ELECTRIC SHOCK  
DO NOT OPEN THE CABINET  
REFER SERVICING TO  
QUALIFIED PERSONNEL  
 
MAINS CONNECTIONS  
Your amplifier has been factory set to the correct mains voltage for your country. The voltage  
setting is marked on the serial badge, located on the rear panel. Check that this complies with your  
local supply.  
Export units for certain markets have a moulded mains plug fitted to comply with local requirements.  
If your unit does not have a plug fitted the colored wires should be connected to the appropriate plug  
terminals in accordance with the following code.  
GREEN/YELLOW  
BLUE  
BROWN  
EARTH  
NEUTRAL  
LIVE  
terminal  
terminal  
terminal  
As the colors of the wires in the mains lead may not correspond with the colored marking identifying  
the terminals in your plug proceed as follows;  
The wire which is colored GREEN/YELLOW must be connected to the terminal in the plug which is  
marked by the letter E or by the safety earth symbol or colored GREEN or GREEN and YELLOW.  
The wire which is colored BLUE must be connected to the terminal in the plug which is marked by  
the letter N or colored BLACK.  
The wire which is colored BROWN must be connected to the terminal in the plug which is marked  
by the letter L or colored RED.  
DO NOT CONNECT/SWITCH ON THE MAINS SUPPLY UNTIL ALL OTHER CONNEC-  
TIONS HAVE BEEN MADE.  
 
CONNECTING YOUR AMPLIFIER  
Setting up your amplifier is rather easy.  
1. Connect all source components (turntable, CD, Tuner, Tape DAT, etc.) to your preamplifier.  
2. Connect the interconnects from the output of the preamplifier or switching center to the  
RCA input on the top rear of the amplifier.  
3. Connect the hot or "+" speaker cable to the red binding post and the common or "-"  
speaker cable to the black binding post (See diagram 2). Ensure that the other end of the  
cable is connected correctly to the speaker. Tighten the binding posts by hand. If you  
use a nut-driver (3/8") do not over-tighten the posts or you may breaak the connection  
inside the amplifier.  
4. Insure that the "mains" switch on the front panel is in the "off" or "0" position.  
5. Turn on Preamplifier and any source components you plan to use.  
6. Plug amplifier into wall outlet.  
7. Turn on the amplifier and allow it to 'warm up' a minute or so before playing any audio  
signal.  
8. Turn up the volume and enjoy.  
 
BIAS PROCEDURES  
The Manley 50 Watt Amplfier is a fixed bias system that requires very little attention. If you wish to  
adjust or check the bias, complete the following steps. For this procedure you will need a multimeter  
to read millivolts (less than 2 volt range) and a small flat screwdriver.  
1.  
Looking at the front section of the top plate of the amplifier, you can see 4 red tip jacks and 1  
black tip jack. To measure the current draw of each output tube place the positive probe (red) into  
the red tip jack for the tube you wish to measure and the negative probe (black) in the black  
(GROUND) tip jack and set the meter to read 'millivolts'.  
2.  
Each of the four (4) output tubes can have its own bias adjusted by altering its own bias  
adjust pot. The numbering sequence for the 4 output tubes runs from left to right, as do the  
corresponding tip jacks (measurement points). The bias adjust pots are located on the top side of  
the amplifier, therefore it will be NOT be necessary to remove the bottom cover to changing the  
bias. They also read left to right.  
3.  
The first step to setting the bias is to turn on the amplifier and insure that there is zero signal  
input. Also, leave your loadspeakers connected as these provide an ideal load on the output. Never  
operate your amplifiers without a suitable load or speakers attatched. It is recommended that you  
leave the amplifier on long enough to ensure that the tubes have reached their stable current draw.  
5.  
Set your meter to read VOLTS DC. You will be measuring less than 1 volt so set your meter  
for a low range if it is not an autoranging meter. Place the probes in the first red tip jack (negative  
probes remains in the black tip jack for whole biasing procedure) and adjust the first bias trim pot  
located on the left side top deck of the amplifier until you measure approx. 200 mVDC (0.2VDC).  
Since you are measuring across a 10 ohm cathode resistor, this would correspond to a 20 mA bias  
current.  
6.  
If you are unable to bring the bias voltage down to 200 mV on any tube then we recommend  
that the tube be carefully watched or replaced.  
7.  
Follow step five with the remaining tubes. Once they are all set, your amplifier should be in  
perfectoperation.  
 
OPERATIONAL NOTES  
SWITCHINGON  
The power switch is located on the lower left hand corner of the front panel. Push the top of the  
rocker switch (1) to turn on the amplifier and the bottom of the rocker to turn off the amplifier. The  
LED on the right side of the front panel will illuminate indicating that the amplifier is operating. Do  
not turn on and off the amplifier in rapid succession.  
RUNNING  
It is not recommended that you leave your amplifier permanently switched on. This only wastes  
electricity and tube life. Your amplifier has solid state rectification and reaches peak operating  
condition in approximately 30 minutes.  
TUBELIFE  
As with all tubes, their quality degrades with age. This is due to cathode emission, a natural process  
found in all tubes. We recommend that you have your amplifier checked every 3-4 years, depending  
on usage, sometimes the amplifier will require re-tubing after this time has elapsed, although we  
have many cases of extreme long life recorded-- 40,000 hours and still counting!.  
SPECIAL NOTE  
The Manley 50 Watt Monoblocks are equipped with a voltage change-over switch located under the  
bottom cover. Insure that this switch is set at 110 if your mains voltage is 100,110,120, or 127  
Volts. Set this switch to 220 if your mains voltage is 220, 227, or 240 Volts.  
Changing the light bulb:  
The lamp which back-lights the Manley insert on the faceplate is a fuse-lamp style lamp. Should it  
burn out, turn off and unplug the amplifer from the mains first. Then remove the bottom cover.  
Carefully pry out the old lamp from its clips and replace with one of the same type. Although it  
looks like a fuse, it is really a light bulb!! Don't put a fuse in there!!  
The fuse lamp is 1 1/4" x 1/4" 8Volts, 300mA.  
Fuses:  
Always replace with same type and rating. Should the B+ fuse blow (the fuse nearer to the output  
binding posts) this usually indicates a tube has blown. One should visually inspect the pcb to look  
for any burnt resistors a blown tube may have taken out. Also a good test is to measure the resistance  
of each catode resistor. This is done in a similar fashion to checking the bias, except do this test with  
the amplifier turned OFF, and set your meter for Ohms. Each cathode resistor should measure 10  
ohms.  
 
SPECIFICATIONS  
Vacuum Tubes:  
4 x EL84, 1 x 12AT7WA, 1 x 6414  
53 Watts  
Output Power  
Frequency Response, +/- .5 dB  
Input Sensitivity  
20 Hz - 20 KHz  
460 mV  
Input Impedance  
100 KOhm  
Load Impedance  
S/N Ratio @350W  
5 Ohm. Factory preset for 5 Ohm  
-80 dB  
Power Consumption  
Mains Fuse  
100 Watts  
168 Watts  
Quiescent  
Full Power  
100, 110, 120V  
220, 240 V  
3 A (Slo-Blo)  
2 A (Slo-Blo)  
Dimensions  
Weight  
W=11, D=8, H=4.5 inches  
11 lbs  
 
WARRANTY  
All Manley Laboratories equipment is covered by a limited warranty against defects in materials  
andworkmanshipforaperiodof90daysfromdateofpurchasetotheoriginalpurchaseronly.A  
furtheroptionallimited5yearwarrantyisavailabletotheoriginalpurchaseruponproper  
registrationofownershipwithin30daysofdateoffirstpurchase.  
Properregistrationismadebyfillingoutandreturningtothefactorythewarrantycardattachedto  
this general warranty statement, along with a copy of the original sales receipt as proof of the  
originaldateofpurchase. Only1cardisissuedwitheachunit, andtheserialnumberisalready  
recordedonit.  
Ifthewarrantyregistrationcardhasalreadybeenremovedthenthisisnotanewunit, andis  
therefore not warranted by the factory. If you believe this to be a new unit then please contact the  
factorywiththedetailsofpurchase.  
Thiswarrantyisprovidedbythedealerwheretheunitwaspurchased,andbyManleyLaboratories,  
Inc. Underthetermsofthewarrantydefectivepartswillberepairedorreplacedwithoutcharge,  
exceptingthecostoftubes.Nowarrantyisofferedontubes,unless:  
1. A Manley Laboratories preamplifier is used with a Manley Laboratories amplifier.  
2. The warranty registration card is filled out.  
In such a case a 6 month warranty on tubes is available with the correct recording of the serial  
numberofthepreamplifieronyourwarrantyregistrationcard.  
IfaManleyLaboratories productfailstomeettheabovewarranty,thenthepurchaser'ssole  
remedyshallbetoreturntheproducttoManleyLaboratories, wherethedefectwillberepaired  
without charge for parts and labor. The product will then be returned via prepaid, insured  
freight, method and carrier to be determined solely by Manley Laboratories. All returns to the  
factory must be in the original packing, (new packing will be supplied for no charge if needed),  
accompanied by a written description of the defect, and must be shipped to Manley  
Laboratories via insured freight at the customer's own expense. Charges for unauthorized  
service and transportation costs are not reimbursable under this warranty, and all warrantees,  
express or implied, become null and void where the product has been damaged by misuse,  
accident, neglect, modification, tampering or unauthorized alteration by anyone other than  
Manley Laboratories.  
Thewarrantorassumesnoliabilityforpropertydamageoranyotherincidentalorconsequental  
damagewhatsoeverwhichmayresultfromfailureofthisproduct.Anyandallwarranteesof  
merchantabilityandfitnessimpliedbylawarelimitedtothedurationoftheexpressedwarranty.  
AllwarranteesapplyonlytoManleyLaboratoriesproductspurchasedandusedintheUSA.  
Somestatesdonotallowlimitationsonhowlonganimpliedwarrantylasts, sotheabove  
limitations may not apply to you. Some states do not allow the exclusion or limitation of incidental  
orconsequentialdamges,sotheaboveexclusionmaynotapplytoyou.  
Thiswarrantygivesyouspecificlegalrightsandyoumayalsohaveotherrightswhichvaryfrom  
state to state.  
 
WARRANTYREGISTRATION  
We ask that you please fill out this registration form and send the bottom half to:  
MANLEY LABORATORIES  
REGISTRATION DEPARTMENT  
13880 MAGNOLIA AVE.  
CHINO CA, 91710  
Registration entitles you to product support, full warranty benefits, and notice of product  
enhancements and upgrades. You MUST complete and return the following to validate your  
warranty and registration. Thank you again for choosing Manley Laboratories.  
MODEL ____________________ SERIAL No. ______________________  
PURCHASE DATE ______________ SUPPLIER ______________________  
--------------------------------------------------------------------------------------------------------  
PLEASE DETACH THIS PORTION AND SEND IT TO MANLEY LABORATORIES  
MODEL ____________________  
SERIAL No. ______________________  
PURCHASE DATE ______________ SUPPLIER _______________________  
NAME OF OWNER _______________________________________________  
ADDRESS ______________________________________________________  
CITY, STATE, ZIP________________________________________________  
TELEPHONE NUMBER ___________________________________________  
Serial #'s of Associated Manley Laboratories Equipment ___________________  
________________________________________________________________  
 

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