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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