Ad200 manualwritten by Grzegorz Sawa-Boryslawski (boro@dustblow.com)
 



I N T R O D U C T I O N
I’ve written this manual for AD200 users, beacue Orange do not provide one with 
their amplifiers (e.g. mine came with manual from Rockerverb!:). Also, there’s 
no manual on their website... and there are billion questions. Informations on 
this site are not authorised by Orange Amplification, these are my thoughts and 
my point of view at this amplifier – from musician – to musicians all over the 
world! There are billion questions worldwide about his amp, basically – the same 
over and over again, so maybe this one will answer most of them (I hope so!:). 
This user’s manual was written for MK3 model, but there’s a lot sommon things 
here with MK1 & MK2 models... so sit and enjoy!


B A S I C S : P L E A S E  R E A D !
Orange AD200B is a tube amplifier. There are hunderds of volts inside that may 
hurt you or kill you! Mind this! Don’t unscrew the amp if you’re not sure about 
what you’re doing or you’re doing it for the first time. Don’t touch anything 
inside EVEN WHEN THE AMPLIFIER IS OFF! Capacitors are charged for some time 
after dsiconnecting from AC. To discharge them, disconnect power cable and turn 
power and standby switch on/off few times. We’re talking about HIGH VOLTAGE 
inside that goes up to 700V! Mind that again! Next, don’t touch the tubes, 
THEY’RE SUPER HOT, even after disconnecting the amp! You can burn your skin 
easily. Wait ½ hour and let the tubes cold a bit. Always remove tubes with clear 
cotton cloth - if tube breaks you’ll not cut your hands - also – you’ll not 
leave your salty fingerprints on them which damages the glass when the tubes are 
working. Do not power AD200B without speaker load. You should always have your 
head connected to the speaker. Even if you just record to your computer with the 
slave out – you must connect AD200B to the speaker.

I will not take any responsibility of damaging your amplifier - 
you can read it and all that you do with your AD200B, you do it on your own 
risk. Right? 


H I S T O R Y
Orange AD200B MK3 is all-tube British bass amplifier designed in the late 90’s 
when the “AD” series began. Advertised as 200W power, 4x6550 (or KT88) tubes, 
2xECC83, 1xECC81 (driver) preamp tubes. There were 3 versions of this head, 
AD200 MK1, AD200 MK2 – these two models ran a total of 200 pieces and were 
handcrafted, point-to-point wired amplifiers. They also differ in cosmetics from 
current production MK3 model (which is a PCB-constructed). As users tell – there 
is probably no difference in the sound of both, PC-Board MK3 and previous 
limited series, MK1 & MK2 (also, MK1 and MK2 had only two preamp tubes – 1xECC81 
and 1xECC83). Point-To-Point is a method of construction when every electronic 
piece is soldered to the wire (and to another piece), sometimes using “turret 
boards” which are plates with holes to put there resistors, capacitors, etc. 
PC-Board are like mainboards in computers – huge board, printed conductive 
pathways, everything soldered to it (faster and easier to make it in automatic 
processes, like factories)
      inside AD200B MK1 (left)  vs  AD200B MK3 (right)
 
F R O N T  P A N E L : T W O  I N S T R U M E N T  I N P U T S

PASSIVE is considered as NORMAL input for most basses, 
ACTIVE – for these which uses active EQ/Pickups (e.g. Fender Jazz Bass Deluxe) 
or have very high output from the pickups (e.g. Fender Telecaster Bass). If you 
put active instrument in passive input you’ll probably hear overdriven tone, 
even when the GAIN knob is set low. If you put passive instrument into active 
input, you will have less headroom (amplifier will be quieter) but you can crank 
up GAIN and MASTER and make your amp sound better on lower volumes (e.g. when 
you play in practice room with the band).


F R O N T  P A N E L : P O W E R I N G  T H E  A M P L I F I E R
As most tube amps, AD200 have two switches. At first – hit this one on the left, 
labeled POWER - this will start the amplifier and power up the tubes. Hit 
STANDBY after min. 30 seconds (better few minutes, I tell ya) and start playing 
:) The orange LED should light up when you hit power. If it’s not – call Orange 
and get a replacement. Also when you hit power, you can hear (and feel) some 
minor buzzing and shaking for a second – this is all normal and tube amps does 
things like that when the voltage is applied to the huge transformers.

2-switch patent is made for the tubes to last longer (c’mon, we all want that!) 
– 
when you hit standby, very high voltage is applied to the power tubes and you 
can play the amp. 

When you switch power and standby at one time (e.g. you want to start playing 
immediately) is like applying high voltage to the tubes that aren’t warm enough 
and of course that shortens their life a bit. If you’re doing a break or you’re 
after soundcheck at your gig – hit standby to the off position, but keep the 
power on! Tubes will stay warm and when the gig starts just put standby on and 
you have that sweet warm tone again, without warming the amplifier from the 
beginning. Get it? :)
F R O N T  P A N E L : C O N T R O L S
MASTER – this knob controls overall, master volume of the amplifier, 
TREBLE – controls amount of treble, 
MIDDLE - Controls amount of mid tones
BASS - Controls amount of bass freq
GAIN – Control amount of gain/overdrive
If you want some dirty tones crank GAIN up and set MASTER to control your 
overall volume. If you want some cleaner tones – set GAIN on lower setting 
(below 1/3) and crank MASTER up. This is probably the best and more versatile 
setting for this amplifier. With MASTER set high you’ll also hear amplifier 
distorted but that are the sweetest overdrive tones coming from power tubes.  
Also, EQ controls on the AD200B are passive, which means that they are 
subtractive - when treble, middle and bass are turned full-up that means they’re 
set factory flat (no EQ, no correction). So when we turn knobs down from “all 
the way up”  we cut these frequencies. AD200B is advertised as the simplest and 
purest bass amplifier probably according to short signal path – less electronics 
inside – which means less loss of signal & more transparency, giving the best of 
your bass guitar own character rather than coloring the sound.


B A C K  P A N E L : S P E A K E R  C O N N E C T I O N S

There are 3 speaker outs: 2x 4ohm, 1x 8ohm
WHEN YOU HAVE: ONE 2ohm CABINET:
There is no way to connect a 2ohm cabinet to AD200B.

WHEN YOU HAVE: TWO 2ohm CABINETS:
This can be done if your cabinets are wired in serial (remember that most of 
them are
wired in pararell) and you will have probably rewire them to work in serial.
If you do this, connect 1st cabinet to 2nd cabinet and then to 4ohm output in 
AD200B (no matter which one).

WHEN YOU HAVE: ONE 4ohm CABINET:
Connect the cabinet to the 4ohm output (doesn’t matter which one)
WHEN YOU HAVE: TWO 4ohm CABINETS:
This can be done if your cabinets are wired in serial (remember that most of 
them are
wired in pararell) and you will have probably rewire them to work in serial.
If you do this, connect 1st cabinet to 2nd cabinet and then to 8ohm output in 
AD200B (no matter which one).

WHEN YOU HAVE: ONE 8ohm CABINET:
Connect cabinet to 8ohm output.
WHEN YOU HAVE: TWO 8ohm CABINETS:
Connect 1st cabinet to 4ohm output, 
connect 2nd cabinet to the second 4ohm output
OR
when your cabinets support parallel chaining: 
Connect 1st cabinet to 4ohm output, then connect 2nd cabinet to 1st cabinet.
WHEN YOU HAVE: ONE 16ohm CABINET:
This can be done only by pulling out a pair power tubes (1 and 3 or 2 and 4), so 
the output transformer will send 2x higher impedance to the speaker jacks. Of 
course, if you pull out these tubes, you’ll loose some power (headroom), but you 
will not damage your speaker cabinet. 
So if you do this – connect your cabinet to 8ohm output.
WHEN YOU HAVE: TWO 16ohm CABINETS:
This can be done only by pulling out a pair power tubes (1 and 3 or 2 and 4), so 
the output transformer will send 2x higher impedance to the speaker jacks. Of 
course, if you pull out these tubes, you’ll loose some power (headroom), but you 
will not damage your speaker cabinet. 
So if you do this – connect 1st cabinet to 4ohm output, connect 2nd cabinet to 
the second 4ohm output
OR
when your cabinets support parallel chaining: 
connect 1st cabinet to 8ohm output, then connect 2nd cabinet to 1st cabinet.


REMEMBER! USE ONLY HIGH QUALITY PROFESSIONAL SPEAKER CABLE!
YOU CAN’T USE MONO JACK/JACK GUITAR CABLE! IF YOU DO THIS YOU CAN BLOW YOUR AMP 
OR CAB!

B A C K  P A N E L : F U S E S


AD200B MK3 has 4 fuses which controls voltage being applied to the electronics. 
Two of them are main and HT fuse which will blow if there’s wrong voltage around 
the inpute/IEC cable, and the other two are power tube fuses, deafinitely not 
frequently seen in the amplifiers. This is part of the Orange’s Tube Failure 
Protection System. AD200 has four power tubes. Before something bad will happen 
– e.g. when the tube breaks down - the amp will blow a fuse - which means that 
it disconnects a 1 pair of tubes (one of them is that tube that went wrong) and 
continue working on the other pair, giving less power, but man, you can finish 
the gig! Pairs are written below the fuses: 1) first and third tube, 2) second 
and fourth tube. The red light above the fuse will tell you that something was 
wrong and the fuse blew. Go to the nearest Radio Shack or electronics shop and 
buy at least few of each fuse – always keep it with the amplifier – voltage 
around the world is tricky and can do bad things :) Don’t worry, they will cost 
you together less than a can of Coca-Cola! 

Fuses are: 2x Fast-Blow 500mA, 1x Time-Blow 1A, 1x Time-Blow 250mA and 1x 
Time-Blow 3,15A (220-250V countries) or 1x Time-Blow 6,3A (100-120V countries).

Please note that MK1 and MK2 models have slightly different fuses (check your 
amps back plate) and do not have Tube Failure Protection. 
 
B A C K  P A N E L : S L A V E  O U T
This is a mono out to link a external power amplifier (e.g. Orange SLAVE unit 
produced in the 70’s). Basically, it’s direct out from the preamp section, with 
no speaker emulation. It beaves like “PREAMP OUT” or “EFFECTS LOOP IN” when we 
speak about other amps. Dry signal. I’ve used it once in a gig, connected to the 
mixing console and then to PA. Results was quite nice but we put a DI between 
slave out and a console and it was a way better. 

I N S I D E : T U B E S
AD200B MK3 operates 4 power tubes and 3 preamp tubes.  When you buy the amp new, 
it will be probalby equipped with 4 Svetlana 6550 power tubes (although not 
labeled) and some chinese preamp tubes (1xECC81, 2xECC83) – note that MK1 and 
MK2 models have only one ECC83 and one ECC81 on preamp! 

Power tubes give the amplifier power/wattage, preamp tubes shape the sound 
(gain, overdrive, tonality). MK3 model can handle also KT88 tubes (you can 
change instead of 6550) – they differ in construction & size and have slightly 
more power than 6550. Some may prefer KT88 due to later break-up and less 
“driven” tone. They also tend to last longer than 6550’s. MK1 and MK2 can’t 
handle KT88 tubes because of tighter spacing between them (KT88’s are wider than 
6550’s). Orange is advertised as 200W output power, but speaking seriously, it 
cannot produced more than 184 watts RMS due to lower plate dissipation of the 
power tubes (184w RMS is calculated for KT88 tubes. 6550’s has slightly lower 
wattage, about 168 watts).

I N S I D E : R E T U B I N G ?
Your amp needs retubing when: something’s wrong with the sound, microphonics, 
strange noises, hum, cracking, low dynamics, very early distortion, little 
headroom, no sound... and many more reasons. These things are mostly one thing: 
BAD or USED tubes. As any lightbulb (which tubes are too), these ones also break 
and stop working in some time. It’s very hard to detremine life of your tubes. 
This depends on a brand, construction, usage, voltage, heat inside amplifier, 
etc. I can tell that if you put there a set of good current production tubes 
into AD200B, and if you play two times a week for 3-4 hours and ocassionally do 
some gigs, your power tubes will last about 2 years, pre-amp tubes about 4 
years. But hey, this is only my calculation. If you play really loud and really 
hard they may last less than a year.. If you play at lower volumes like one time 
a week, they will last for years.


I N S I D E : C H A N G I N G  P R E A M P  T U B E S
You can change preamp tubes by yourself, those are three (MK3 model) small 
tubes, usually covered by a metal shields (these prevent from getting 
microphonics and other noises from electronic components inside). V1 and V2 are 
ECC83 (12AX7) tubes, V3 is ECC81 (12AT7). These tube sockets are the same and 
you can experimtent putting other tubes in all places to get “your tone”. 
(ECC81/12AT7, ECC82/12AU7, ECC83/12AX7, E83CC, ECC803s... if you want to try 
other tubes, better ask a tech if that tube you want is compatible with these). 
You’ll probably notice major change in sound when changing V1 (first gain stage) 
and V3 (phase inverter, giving big meal to power tubes:). For more informations 
about phase inverter, gain stages and specification (gain) of the tubes above, 
please search the net – tons of useful stuff there.
   
I N S I D E : C H A N G I N G  P O W E R  T U B E S  /  B I A S I N G
And this is more complicated... You CAN’T change your power tubes in AD200B if 
you don’t have special hardware (e.g. Weber Bias Rite, Amptone BIASCOM or 
similar). Let me explain ths a little bit... This is 200W tube amp. This is a 
lot watts for a tube amp! Lower-powered tube amps are cathode biased, which 
means that you can change power tubes to a new set without changing BIAS (bias 
is voltage which is applied to power tubes - amplifier do this automatically, 
there’s not pot or switch). So you ask – why AD200B isn’t a cathode-biased amp – 
tech’s say that cathode-bias system in a 200W amp will eat a lot of watts 
(headroom) and probalby you’ll have about 100W in the same amp. So, you must buy 
a quartet of good tubes. 6550’s or KT88’s – depends on what you like. 

You must measure current voltage flowing into your tubes – I bought Amptone 
BIASCOM, carefuly unscrew chassis, placed amptone between V4 socket and the 
tube, connected to the speaker, then powered the amplifier (I let AD200B warm up 
for 15 minutes), then I hit standby, set all controls to zero. On the stock 
(old) tubes it measured 27,5mA. It was a little on the high side, because 
according to Orange technicians, best results are between 18-22mA. Look at the 
picture below. Take a small screwdriver and adjust bias pot (when the amplifier 
is on). Adjust it carefuly! You’ll see that very minor change in adjusting the 
pot result in huge change of the voltage. If you want your tubes to last longer, 
you may bias it on a colder side (~18mA), but you the sound may be a little less 
open, less driven and less dynamic. If you want full sound with great, creamy 
overdrive, rock, dynamic tone, bias it on the hot side (~22mA). Tubes will be 
running hot and they will probably last shorter. If you dig the natural, “stock” 
tone of this amp, bias it near 20mA. Nothing’s for free! 
One more thing - because power tubes in AD200B work in pairs, placing Biascom on 
the first tube socket, we’ve measured just the first pair (1st and 3rd tube). 
Now we must check that the other pair (2+4) is good – it should be the same or 
very close to to first pair (should be no more than ~2mA difference). If the 
difference is greater than 2mA, you bought wrong matched quartet (no the same 
parameter on each tube) or some of them was damaged during the shipment (or 
something like that).  I bought new TungSol 6550’s quartet – and one tube was 
probably damaged. I cannot adjust the trim pot for correct 18-22mA range, 
because the lowest setting I can do was about 30mA... Then I bought JJ KT88’s 
(no major difference in sound comparing to 6550’s) and had a range of 7-35mA to 
adjust so it stuck on about 21mA. That works for me. Bias will drift on sides 
when playing amp for a long time or it can drift just because of shaking during 
the transport. So, check bias every half a year if you use it heavily and gig 
with it. 

  
T H E  E N D
If you have any questions you can e-mail me at boro@dustblow.com or catch me on 
the Orange forum (“boroman”)
Thanks for Sooner and other members of Orange Forum for correcting my mistakes.