Manley Labs Stereo Amplifier SE PP 300B User Manual

MANLEY  
LABORATORIES, INC.  
OWNER'S MANUAL  
MANLEY SE / PP 300B  
"RETRO" 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 SE / PP 300B TRIODE Monoblock Amplifiers. Designed by David Manley, the Manley  
SE / PP 300B TRIODE Amplifiers use only the best available components, with the shortest and cleanest signal  
path possible. These amps have the unique ability to switch from Single ended to Push-Pull topologies and the  
ability to adjust the amount of negative feedback in 1 dB steps. This amp is designed to provide our customers  
with a versatile little amplifier that can do it all.  
Let us start out by stating our opinions about amplifier topologies. Historically, we have been manufacturing very  
highly regarded tube amplifiers since before tubes were considered the best option for hi-fi music lovers. We have  
manufactured a very wide range of amplifiers with power ranging from 15 watts to 800 watts and with a  
corresponding variety of tubes. This is not our first amp to feature 300Bs nor our first single ended triode amp.  
We build a $15,000 70+ watt single ended amp on a custom basis. In our experience, the more power an amplifier  
is capable of - the better it will be at providing acceptable low frequency quality. It is not easy to produce a very  
powerful amp with highs of the same quality as the lows. To do that we had to start manufacturing our own  
transformers. This is the major development that allowed us to produce an amplifier that could switch from  
single-ended to push-pull. We had to design and build a very unusual transformer first.  
When several other manufacturers started selling single-ended amps with 5 to 9 watts of power, we understood  
subjectively and objectively the good part of the story - the superb mid range - the delicate transient detail - the  
inherent simplicity. The bad news was that there were almost no speakers efficient enough to be a dynamic viable  
system. The worse news was that either these single-ended amps cost more than the condo or they had specs that  
could only be a joke. As the triode fans increased, more efficient speakers became available and several fanatics  
began to dismiss push-pull as a bad thing to be avoided at all costs. We objected to such blanket generalities and  
stressed that the push-pull done right with truly balanced transformers, quality parts throughout and a well  
designed circuit has proven to be a superb technique. We also like single ended amps, but few and far between,  
mostly because we prefer a flat frequency response and low distortion. We knew could do it better.  
We set out to design an amplifier that would appeal to us and to you and to the critics. It would be single-ended  
with more power than most for fans of that topology. It would be switchable to push-pull for fans of that school  
and for those who want it both ways - to compare for themselves, and to use each mode depending on the music.  
We decided to further extend our own feature of variable negative feedback to a greater range - from none to 10  
dB. Some prefer zero negative feedback and some prefer more. The advantage of a little negative feedback is  
better specifications in general. Williamson, in 1947, not only described the advantages but described the loss of  
some transient information with greater than 20 dBof feedback. We typically use 3 to 6 dB in other amps. Even  
with zero negative feedback, this amp is cleaner and flatter than any single-ended amp we know of. One  
interesting aspect of negative feedback is it gives a higher damping factor. Conventional wisdom would have us  
think that the higher the damping factor - the better. Our experience is that the optimum damping factor is not  
infinity and that it depends on the speaker, the room, and the taste of the listener. In other words, the optimum is  
variability, and this we provide. This amp satisfies us as long time amplifier builders, amazes the critics in several  
well known magazines and is bound to satisfy the you with the ability to fit into your system and your  
expectations.  
We offer two versions of this amplifier. One version uses a 5V4 tube rectifier and 6SL7 & 6SN7 input stage. The  
chassis is more rectangular. This retro-look has appeal in the far-east and this version is only built for that part of  
the world. We also build a more conventional looking amp for our American and European customers. These use  
a solid state rectifier and12AT7 / 7044 input stage similar to our other amps. Otherwise the amps are brothers  
both in circuit and performance. Both amplifiers have a highly polished look thanks to the gold and chrome  
finishes. These new metal technologies were not available a few years ago. Built to last a lifetime. Designed to  
look elegant. Engineered by David Manley who happens to love music enough to be his lifes career.  
 
READ THIS PAGE BEFORE YOU SET UP THE AMPS, PLEASE  
IMPORTANT Never operate this amp without a speaker or load connected. Never drive this amp into a short  
circuit. Most solid state amps can be operated without a load or speaker and some can drive a short circuit because of  
protection circuitry. These are different - Like most tube amps the output power is less affected by changing the load  
impedance within the range of 4 to 16 ohms, however extremes like a short or open circuit are to be avoided. The result  
could be damage to transformers, tubes. The warranty does not cover this damage if it occurs.  
INSERTING TUBES  
We ship these amplifiers with the 300B tubes boxed separately because they are fragile and expensive. You will have to  
insert these before turning the amplifier on. Carefully upack the 300B tubes from their box and ensure they have not  
been physically damaged. We have labelled each tube and its corresponding socket. Notice that there are two thick pins  
and two thinner pins on the base of the 300B. The two thick pins MUST be alligned and oriented to go into the two  
larger holes in the socket. It is possible to plug this tube in the wrong way - so pay careful attention to the pin alignment  
on these tubes. Now plug the right tube into the right socket the right way. This is easy but important.  
Pa y sp ecia l a tten tio n to p in  
a lign m en t ! Th e 2 sm a ll p in s m u st  
go in to th e 2 sm a ll so cket h o les.  
Th e tu b es m u st b e in ser ted  
ca r efu lly a n d sp ea ker s  
co n n ected b efo r e tu r n in g th e  
a m p o n .  
GENERAL NOTES  
LOCATION & VENTILATION  
The Manley SE/PP 300B 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 amplifiers, such that a constant flow of air can flow. Do  
not place amplifiers directly on high pile carpet or any other surface that will block the ventilation vents underneath the  
amplifiers. If you have small children or pets, you should consider placing the amplifiers out of reach to prevent damage  
to the amplifier or damage to your small children or pets by the amplifier as the tubes  
WATER & MOISTURE  
As with any electrical equipment, these amplifiers should not be used near water or moisture. If liquid enters the  
amplifier, it must be immediately returned to your dealer for servicing.  
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  
SPECIAL NOTES  
Before turning the amps on - Connect your preamp to the amp inputs then turn the preamp on. Tubes may become loose  
during transit. Straighten and press down each tube before plugging the amplifier into the mains socket. Furthermore,  
do not touch the tubes after the amplifier has been switched on, as the tubes become very hot during operation and  
should only be handled after the power has been turned off and the tubes have cooled.  
HUM  
As with most monoblock amps with the 3 pin IEC power connectors, you may need one or two "3 pin to 2 pin" power  
adapters or "cheaters". This will stop ground loop related hum. Usually only one amp will need this.  
WARNING!  
TO PREVENT THE RISK OF ELECTRIC SHOCK DO NOT OPEN THE CABINET.  
REFER SERVICING TO QUALIFIED PERSONEL.  
 
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 coloured wires should be connected  
to the appropriate plug terminals in accordance with the following code.  
GREEN/YELLOW  
BLUE  
BROWN  
EARTH  
NEUTRAL terminal  
LIVE terminal  
terminal  
As the colours of the wires in the mains lead may not correspond with the coloured marking  
identifying the terminals in your plug proceed as follows;  
The wire which is coloured 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 coloured GREEN or GREEN  
and YELLOW.  
The wire which is coloured BLUE must be connected to the terminal in the plug which is  
marked by the letter N or coloured BLACK.  
The wire which is coloured BROWN must be connected to the terminal in the plug which is  
marked by the letter L or coloured RED.  
DO NOT CONNECT/SWITCH ON THE MAINS SUPPLY UNTIL ALL OTHER  
CONNECTIONS HAVE BEEN MADE.  
 
CONNECTING YOUR AMPLIFIER  
Setting up your amplifiers 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 amplifiers.  
3. Connect the hot or "+" speaker cable to the red binding post and the common  
or "-" speaker cable to the black binding post (See diagarm 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 break the connections inside the amplifier.  
4. Ensure that the "mains" switch on the front panel is in the "off" or "0" posi-  
tion. If the 300Bs are not inserted - do it now - the instructions are on page 4.  
5. Turn on Preamplifier and any source components you plan to use.  
6. Plug Amplifiers into wall outlets.  
7. Set both amps up at the same settings. A good place to start is both amps set  
to S / E 18 WATTS and 3 dB of FEEDBACK.  
8. Switch the square mains power switch to the ON or "1" position and allow  
the amplifier a minute or so to 'warm up'. The glowing panel and glowing  
tubes will indicate that the amplifier is on.  
9. Turn up the volume on the preamp and enjoy. If something is "humming"  
don't panic. All you need to do is use a "3 pin to 2 pin AC adapter" or  
"cheater". If you don't have one they are available at most hardware stores  
for about a dollar. Usually one amp will need it but sometimes both. This is  
because a ground loop exists in the system. Too many grounds - You should  
only have one.  
10. Now, while music is playing, try switching to PUSH / PULL. The differ-  
ence may or may not be subtle. Choose the mode you like best with this  
music. Turn the FEEDBACK switch to 10. The volume has become quieter  
so compensate for the difference at the preamp. Listen a bit until you are  
used to this, then turn down the volume and turn back the FEEDBACK to 0.  
Adjust the preamp for the same volume as the previous test. Now, you  
should have a reasonable opinion of the effects of the FEEDBACK. You can  
turn this control step by step to the position that best matches your speakers  
and tastes. We suggest also experimenting with speaker placement now that  
the "system" has changed. Another very important area for experimentation  
is acoustic treatment. All too often a good system will sound mediocre due to  
acceptance of the surface treatments. Usually a mix of a little broadband  
absorbtion and diffusion is a major improvement. Carpet and other thin  
treatments only absorb highs and can "unbalance" a system.  
 
MANLEY SE / PP 300B TRIODE MONOBLOCK  
AMPLIFIER  
A
B
Q
R
J
N
O
F
H
I
L
C
D
E
K
M
G
P
Amplifier Overhead View  
A
B
C
D
E
F
RCA Input Jack  
XLR Balanced Input Jack ( pin 2 positive )  
Speaker Terminals  
IEC Mains socket  
Mains fuse - Replace only with same type and value  
Tube 5U4 Rectifier  
G
H
I
Tube 5U4 Rectifier  
Power Tube 300B  
Power Tube 300B  
J
K
L
Bias trimmer ( for H & N )  
Bias trimmer ( for I & P )  
Input Tube 6SL7  
M
N
O
P
Q
R
Driver Tube 6SN7  
Bias test point for 300B (H)  
Variable Feedback Switch  
Bias test point for 300B (H)  
Single-Ended / Push- Pull Switch  
Power Switch  
 
OPERATIONAL NOTES  
SWITCHING SINGLE-ENDED 18 / PUSH-PULL 36 This amplifier has the unique feature of  
being able to choose between two circuit topologies. You are able to switch between each mode  
while the amplifier is turned on and playing music. In SINGLE-ENDED mode the amplifier uses  
both 300Bs in parallel. The advantage is a minimalist circuit requiring no "phase splitter",The  
disadvantage is a less efficient circuit that produces half the power of PUSH-PULL. In PUSH-  
PULL mode each tube works in opposite phase to the other and relies on the output transformer to  
make the polarities work together. This has advantages in efficiency and in the distortion and noise  
cancellation properties of a balanced circuit. Both ways are operated in "Class A" bias throughout  
and both are PURE TRIODE and both modes have a similar short signal path.  
SWITCHING VARIABLE FEEDBACK The variable feedback can be changed in 1 dB steps  
from zero to 10 dB. The most obvious effect of changing the amount of negative feedback is the  
gain change. The more feedback - the less gain but also less distortion and a flatter frequency  
response. You should be able to hear that with less feedback, the tonality is more aggresive but the  
imaging may have greater detail. As you increase feedback, the amp gets smoother and softer and  
slightly brighter. Towards the maximum amount of feedback, the amp may begin to sound like a  
good solid state amp. Virtually all solid state amps need large amounts of feedback in order to  
sound acceptable. Maximum feedback also corresponds to maximum damping factor. This control  
not only affects the tonality of the amp but also of the speaker. The optimum setting depends on the  
speaker, the room, and your tastes. Experimentation will be necessary but also fun and educational.  
ADJUSTING BIAS This does more for tube life than it does for sound quality. You will need a  
DC voltmeter and a small flat screwdriver. This should be checked every few months but does not  
need to be necessarily checked and adjusted unless the 300Bs are replaced.  
1) Let the amp warm up in SINGLE-ENDED mode for about an hour, then with no music  
playing.... Set the volt meter to a low DC range.  
2) Put negative or black probe of the voltmeter to a chassis screw (ground) and the red or positive  
probe in the small black socket near the FEEDBACK switch below the tube to be adjusted.  
3) It should read 740 mV or .74 volts DC. If not -then you can adjust the trimmer without opening  
the chassis. It is located in the hole in front of the 300Band is blue.  
4) Now adjust the other 300B bias. Use the other black probe socket and the right side trimmer and  
adjust the same way. A little "drift" is normal .  
5) Switch to PUSH / PULL - you should measure each tube again. The meter should now read  
640 mV but more important should measure the same as the other tube. If not adjust one tube to  
match the one closest to .64 volts. This cancels hum in PUSH-PULL mode. If a 300B will not  
trim as described - then replace it and adjust the bias.  
TUBE LIFE  
You should expect many years of life from the tubes in your MANLEY SE / PP if you adhere to  
the procedures described above and check your bias at least once every 2-3 months. We stock all  
the tubes in these amplifiers should you ever need replacements (and at very reasonable prices too!)  
FUSES  
The fuses used in your amplifier are standard 1/4" x 1 1/4" SLO-BLO types. The correctly rated  
fuse has been installed at the factory for your country's voltage. If replacing a fuse, always unplug  
the amplifier's power cord from the wall outlet and always use the exact same type and ampere  
rating fuse as the one you are replacing. Failure to do so will void your warranty and can be a  
dangerous fire hazard. For 240 volts the correct fuses are MDL1 for the mains.  
 
SPECIFICATIONS  
Vacuum Tubes:  
2 x 300B (Output), 1 x 6SN7 (Driver),  
1 x 6SL7 (Input) 2 x 5U4 (Rectifier)  
Output Power @ 3% THD  
SINGLE-ENDED: 0 dB FB - 18 Watts  
SINGLE-ENDED: 10 dB FB - 25 Watts  
PUSH-PULL: 0 dB FB - 36 Watts  
PUSH-PULL: 10 dB FB - 42 Watts  
Frequency Response +/- .5 dB  
(measured at 5 watts)  
SINGLE-ENDED: 0 dB FB - 15 Hz - 6 KHz  
SINGLE-ENDED: 10 dB FB - 15 Hz - 28 KHz  
PUSH-PULL: 0 dB FB - 10 Hz - 12 KHz  
PUSH-PULL: 0 dB FB - 10 Hz - 60 KHz  
Input Sensitivity  
Input Impedance  
Load Impedance  
1 V nominal, depends on feedback setting  
75 KOhm unbalanced, 220 Kohm balanced  
4 to 12 Ohm appropriate for 4 & 8 ohm speakers  
12 to 20 Ohm appropriate for 16 ohm speakers  
S/N ratio @ 33 watts  
Power Consumption  
Mains Fuse  
Typically 100 dB or a -76 db noise floor 10Hz-30K  
216 Watts  
100, 110, 120V  
220, 240 V  
2 A (Slo-Blo)  
1 A (Slo-Blo)  
Lamp  
1/4 X 1 1/4 Fuse lamp - 8 volt, 0.3 amp  
W=8, D=21, H=7 inches  
30 lbs EACH  
Dimensions  
Shipping Weight  
 
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.aManleyLaboratoriespreamplifierisusedwithaManleyLaboratories amplifier,and  
2. thewarrantyregistrationcardisfilledout.  
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  
withoutchargeforpartsandlabour.Theproductwillthenbereturnedviaprepaid,insuredfreight,  
methodandcarriertobedeterminedsolelybyManleyLaboratories.Allreturnstothefactorymust  
beintheoriginalpacking,(newpackingwillbesuppliedfornochargeifneeded),accompaniedby  
awrittendescriptionofthedefect,andmustbeshippedtoManleyLaboratoriesviainsuredfreight  
atthecustomer'sownexpense.Chargesforunauthorizedserviceandtransportationcostsarenot  
reimbursableunderthiswarranty,andallwarrantees,expressorimplied,becomenullandvoid  
wheretheproducthasbeendamagedbymisuse,accident,neglect,modification,tamperingor  
unauthorizedalterationbyanyoneotherthanManleyLaboratories.  
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: MANLEY SE / PP 300B MONOBLOCK  
SERIAL No. ______________________________  
PURCHASE DATE ______________ SUPPLIER _______________________  
NAME OF OWNER _______________________________________________  
ADDRESS ______________________________________________________  
CITY, STATE, ZIP________________________________________________  
TELEPHONE NUMBER ___________________________________________  
Comments???? ___________________________________________________  
________________________________________________________________  
 

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