Well, here's a starting point. I've been using this list for the last couple of years as a starting point for finding manufacturers.

http://www.musician…

ableton
access
adam
adamas strings
adgil monitor surround system
adk microphones
advanced media group
aguilar amps
airtools
akai products direct
akg acoustics
alcorn mcbride
alembic
alesis
algorithmix
all parts
allen & heath
allen guitars
allen organs
alphaton
altech systems
altus flutes
amek
amg
amina
amis
ampeg
ams neve
amx
analog devices
anchor audio
antares
antari
antex digital audio cards
apex
apg
aphex systems
apogee digital
apple itunes
applied magic
applied-acoustics
aptx
arbiter group
arboretum systems
aria
arkaos
armoured cable
ars nova
art
arturia
asc tube traps
ash
ashly audio inc.
atari
audio centron
audio engineering society
audio export
audio precision
audio toys
audio-technica
audiobro(hiwatt booker amps)
audiotrak
audix corporation welcome
aura pro audio
avalon design
avid
avm technology
axis
axon
az fachverlage ag
azden
aztech labs
b.c. rich guitars
b.p.m. studiotechnik
bach
bag end loudspeakers
band-in-a-box
barcus berry
basf
bassplayer magazin usa
bbe
be
bechstein
behringer
bellari by rolls
bellari
benchmark
bestservice
beyerdynamic
beyma deutschland
beyma
bgw systems
bias
big briar
big fish audio
biggagiggas
bill lawrence design
blue chip
blue
bms transducers
boehm
boesendorfer
bogner amplification
boing
boosey hawks
borsini
bose
boss
boss deutsch
botex
bpm tube-mics
brauner german tube mics
brian moore
brother
brownsville guitars
brueel & kjaer
bryston
bss audio
buchla
budda amps
c-audio
c-ducer contact pick-ups
c-mexx
cad
cae inc.
caig laboraties
cakewalk music software
calicchio
calzone cases
camac
case logic
casio
caspari software
cedar audio
celemony
celestion speakers
cerwin vega
chandler guitars
chapman stick
charvel by jackson
citronic
clavia
clay paky
cme keyboards
coda
community
compaq
composing recording mastering
cordial
corel
cort guitars
countryman
crate
creamware
creative labs
crest audio
crown
crystal river eng
d r strings
d&b audiotechnik
d&r
d'addario strings
d'aquisto strings
d.a.s. audio
danelectro
dap audio
dart llc
dartech
das musikinstrument
datasonics
dauz electronic drums
db technologies
dbs digital broadcast systems
dbx professional products
ddrum
de armond guitars
dean markley strings
demeter
denon
denon deutschland
denon
diacoustics
dialog 4
digidesign
digigram
digital audio labs
digital music corp
digital theater systems
digitech deutsch
digitech
dimarzio
dingwall
dirk brauner roehren
dk audio
dobro
dod
doepfer
dolby laboratories
doremi labs(digital video)
dpa
dr. schoeps mics
dramm
drawmer
drum workshop
drumtrax
duracell adam-hall
duracell batteries
duy
dw drum workshops
dynacord cobra
dynacord
dynaudioacoustics studio monitors
e-lab
earforce
early patches
east west
eastern acoustic works
ebow
echo audio
ecler
eden
edirol
eela audio
ees
egnater
egosys
eko
eks-software
electro voice
electronic theatre contols
elektron
emagic usa
emagic
emes products - a designe
emes
emg inc.
eminence speakers
empirical labs
emu
emulator archive
epiphone by gibson
epson
equitech
ernie ball
esp guitar company
eugen guitars
euphonic audio ea
euphonix
eurolite
eurotruss
event electronics
eventide inc.
evi audio deutsch
evi audio
evolution
eye & i productions - voice crystal
fane speakers
fatar master keyboards
fbt
fender
fernandes
fichter
fidelipac
final font solutions
fischer amps
fishman
fmr audio
focusrite
fodera
fohhn
fostex
framus by warwick
frantone
fret-king guitars
friendship
frontier designe
fulltone
furch
furman
future light
g prime
g&l
gabriel drums
gadget labs
galaxy guitars
galli
gallien krueger
garwood
gdt softworks
ge lighting
geerdes
gem
gema online
gemeinhardt online
gemini
genelec: the active approach
general communications
generalmusic
george dennis
german light products glp
gerriets
getzen
ghs strings
gibson
gigmate
gitarre bass magazin germany
godin guitars
gold line
gore music (elixier)
gorilla amps
grace design
gretsch drums
gretsch
greytsounds
griven
groove tubes
groovemaker
grotrian-steinweg
grundig
gsp-users archive
guild
guillemot
guitar world online
haagston
hafler
hal leonard
hall crystal
hama/fotoptical-gear
hamer
hammond
hannabach
hardcase
harmony central
harrison by glw
hart dynamics inc.
hartke
hartmann
haun
hauppauge
hdcd - high definition compatible digital
headspace
hearsafe
heritage guitars
hewlett-packard hp
hhb communications
high end systems
hildner
hipshot
hit bit
hiwatt
hk-audio
hohner germany
hohner usa
hoontech
hosa technology, inc.
hoyer
hughes and kettner
ibach
ibanez
ibm
iclock
ik multimedia
ilio cd rom samples
ilme
imaja
infusion systems
innovative quality software
intel
intelligent devices
international saxophone org
invision
iomega
j.d'addario & company
j.l.cooper
jackson guitars
jamo
jaspers
jay turser guitars
jb-lighting
jbl
jem
jim dunlop usa
jm audio
johannus
johnson amps
jomox
josephson engineering
jupiter
jvc canada
k&k sound systems
k&m koenig&meyer
kaba
kae labs
kaman music
kat percussion
kawai deutschland
kawai
keilwerth
ken smith
kenton
ketron it
ketron
keyboard central
keyboard magazin usa
keyfax
keys deutschland
keys
kiesel guitars
kind of loud
klark-teknik
klein hummel
klipsch
klotz cables germany
kme
koblo
koch
koenig meyer hardware
koenig&meyer english
korg deutsch
korg italy
korg pa80 page
korg uk
korg
krk loudspeakers
ks beschallungstechnik
kueng
kurzweil music
kustom
la audio
la bella
lab.gruppen
lakewood guitars
lakland
Landmark Audio Technologies
laney
larrivee
latin percussion lp
lawson
lds light design system
leasing(grenke) only for german customers
leatherman
lectrosonics wireless
leduc
lefima
lem
leopold mueller
levy's
lexicon
lighthouse digital systems
line 6 amps
lintronics
lite-puter
litec/manfrotto
litecraft
liveupdate
lmp lightcompany (germany)
logitech
logitek (china)
logitek
lowrey organs
lp music group - latin percussion
ltb procase
lucid
lucid
ludwig musser
luk guitars
lynx-studio
m audio deutschland
m audio usa
m-commerce
mach
mackie
macpherson
macromedia
mag-lite
magix
magix
mam(music and more)
manley labs on-line
mapex deutsch
marantz
mark of the unicorn, inc.
marleaux bass guitars
marshall deutsch
marshall
martin audio
martin guitars
martin light
martin professional
masterbits
masterbits
masterwriter
maxell
mbho mikrofonbau haun
mccauley
media dj
mediatrix
melton
merging technologies s.a.
meridian
merseburger verlag
mesa-boogie
metric halo labs
meyer sound
michael tobias design mtd
microboards cd duplication
microsoft
microtech gefell
midas
middle atlantic products
midisoft
miditemp deutsch
miditemp professional midi equipment
millennia media
miller freeman
mindprint
minnetonka
miraphone
mix magazin usa
miyazawa
mobolazer
modulus guitars
moebus
moeck
mogami
mollenhauer
monster cable
montarbo
moog bob
moog music custom engineering
morley
motion sound
motorola
msoft
mtu
muramatsu
music man
musicam usa
musicware
musikmesse frankfurt
musikmesse genf
musitek
mutec digital cards
mutec smart digitals
mxl microphones
mxr
mytek digital
nady systems
native instruments
nec
nemesys
neumann
neuser
neutrik
neve
nexo
niefer
nightpro eq's
njd
nobels
nokia
nordlead
notation software
novation synthesizers
novell
now software
nsi
numark online catalog
numerical sound
ohm
oktava
omnirax
omnitronic
on-line guitar archive olga
onkyo
opcode
optek
optifile
optocore
oram consulting
orange amplifiers
orla
ortofon
otari corporation
ovation deutsch
ovation
oz audio
paiste
palmer
panasonic
parker guitars
parts is parts
paul reed smith guitars
paxman
pearl corporation
pearl river
peavey europe
peavey uk
peavey
pedulla
pg music inc.
phil rees
philips
phl audio
phonic
piano disc
pignose amps
pintech
pioneer
power computing
power technology - dsp fx
powerjam
powersoft
prefer
presonus
prism media products
pro studio magazin
proaudio
procosound (the rat)
proel
progressive networks
promark
propellerhead
prosoniq
purple audio
pyramid strings
qdesign
qms
qsc audio products, inc.
qsound
qsp music
quadral
quantec
quantegy (=ampex)
quart
quiklok
radikal technologies
radio system
ramsa deutsch
randall amps
rane corporation catalog
rcf
rebirth
red sound
reloop
remo drums
renkus heinz
reussenzehn
rhythmtech
richmond sound-design
rickenbacker guitars
rico international
rio grand
rising software
ritter basses
rivera
rmc
rme
rme
rockinger
rocktron
rode
rodriguez
roger mayer effects
roland atelier organs
roland deutsch
roland digital pianos
roland drums
roland guitar products
roland in spanish language
roland keyboards
roland product-search direct usa
roland usa
roland-meinl
rolls
rosco
rosendahl
rotosound
rubisoft
ruby tubes
rupert neve
ryger
s&s industries
sabian
sabine
sabra-som
sadie
sadowsky guitars ltd.
samick
sampletank
samson deutsch
samson
santa cruz guitar
sanyo
sascom
schaller
schecter
schlagwerk
schnakenberg buehnenbau
schoeps
sd systems
se microphones
seagull guitars
seer systems
sek'd
selmer
sennheiser consumer
sennheiser france
sennheiser usa
sennheiser
sequential circuits tm spare-parts manuals
seymour duncan
sgm
shadow pickups
sharp
shermann filterbank
shermann loudspeakers
shs audio
shubb
shure brothers inc.
shure electronics
shure needlz
shure wireless
sibelius-software
sibelius
sidstation(new synth on commodore 64 chip)
siemens beschallungstechnik
silicon graphics
silver
sintefex
skb
slingerland drums
sm pro audio
smoke factory
soli-music
solid state logic ssl
solton craaft musik
sonic foundry
sonic imlants
sonic science
sonic solutions
sonic timeworks
sonor
sonorus
sontronics
sony (japan)
sound check magazin deutsch
sound factory
sound performance lab
sound quest inc.
sound sculpture
sound technology
sound web (bss)
soundblocker
soundcraft
soundfield
soundgraph
soundpool
soundscape
soundtech
soundtrek
spatializer
speck electronics
spector
spectral audio
spectral design
spectrum signal processing
speedball
spendor
spirit
spirit
spl
srs labs
sseyo
stage accompany
stage tech
stanton turntables
starcase (usa)
starclassic
steinberg japan
steinberg-nuendo
steinberg
steinberger
steingraeber
steinway & sons
stick
stoelzel
studer
studio 49
studio projects
studiomaster
swar systems indian music
swissonic
switchcraft
swr
sylvania
symantec
symbolic sound
symetrix audio
synchro arts
syncrosoft
synoptic
synrise
syntec
synthax
syntrillium
syquest
syrincs
systems development group
t-racks software
tad pioneer
takamine
tama
tamburo
tannoy
tapco
tascam usa
tascam
tastenwelt
taylor
tc electronic
tc helicon
tc works
teac/tascam deutschland
tech 21 website
technics keyboards pianos product search
technics musikinstrumente deutsch
telex
telos
terratec
terry rogers guitars
thomastik strings
thx
tl audio
tla
tobias
tom's haedware guide(guitars)
tomcat
toneworks deutsch
toshiba
trace elliot
tracer
transaudio
trident
trident
trigger perfect inc.
triggerhead
true audio
tubetech
turbosound
turtle beach
u&i software
ueberschall
ultimate support
umax
universal audio
ups tracking system
uptown automation systems
valentino production music
vandoren englisch
vandoren french
vari-lite
varta
verity systems
vermona/mephisto
vestax deutsch
vestax
vht amps
vic firth
vidikron
vintage guitar parts
vintage synthesizer spare-parts
virsyn
viscount
visu-lite
visual volume
vmi
voce
voggenreiter
voice crystal
vox
voyetra technologies, multimedia sound specialists
wadia digital
warner brothers
warwick
washburn
wavemechanics
waves
weiss engeneering
whc
whd
wheatstone
whirlwind
wieland
wildcat autoscore
wireworks
wohler monitoring
wybron
xing technology
yamaha amps
yamaha band & orchestral instruments
yamaha blockfloeten
yamaha clavinova series
yamaha concert-percussion
yamaha deutsch
yamaha drums
yamaha guitars basses
yamaha horns
yamaha portable keyboards
yamaha pro-audio
yamaha sax,clarinet etc.
yamaha silent strings
yamaha synthesizer stage pianos
yorkville netwerks
young chang
z-systems audio engineering
zaxcom audio (portable digital audio)
zeck
zefiro acoustics
zendrum
zero 88
zero g
zeta
ziljdian
zinner, hans
zoffmusic
zon guitars
zoom

Well, you'll find on this website some interestings PDFs for download :

Audio Media = Pro Audio Magazine