Rane MA3 User manual

MA3
MULTICHANNEL AMPLIFIER
CONTENTS (in order of appearance)
Important Safety Instructions
MA3 Manual
MA3 Data Sheet
MT6 Data Sheet
Constant-Voltage Audio Distribution Systems
Sound System Interconnection
MA3 Schematics
Warranty
22472
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MA3
MULTICHANNEL
AMPLIFIER
3
CHANNEL OUTPUT HEADROOM
POWER
POWER

ATTENTION: RISQUE DE CHOCS ELECTRIQUE - NE PAS OUVRIR
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION
To reduce the risk of electrical shock, do not open the unit. No user
serviceable parts inside. Refer servicing to qualied service personnel.
e symbols shown below are internationally accepted symbols
that warn of potential hazards with electrical products.
is symbol indicates that a dangerous voltage
constituting a risk of electric shock is present
within this unit.
is symbol indicates that there are important
operating and maintenance instructions in the
literature accompanying this unit.
WARNING
IMPORTANT SAFETY INSTRUCTIONS
1. Read these instructions.
2. Keep these instructions.
3. Heed all warnings.
4. Follow all instructions.
5. Do not use this apparatus near water.
6. Clean only with a dry cloth.
7. Do not block any ventilation openings. Install in accordance with manufacturer’s instructions.
8. Do not install near any heat sources such as radiators, registers, stoves, or other apparatus (including ampliers) that produce heat.
9. Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized plug has two blades with one wider than the other. A
grounding-type plug has two blades and a third grounding prong. e wide blade or third prong is provided for your safety. If the provided plug
does not t into your outlet, consult an electrician for replacement of the obsolete outlet.
10. Protect the power cord and plug from being walked on or pinched particularly at plugs, convenience receptacles, and the point where it exits from
the apparatus.
11. Only use attachments and accessories specied by Rane.
12. Use only with the cart, stand, tripod, bracket, or table specied by the manufacturer, or sold with the apparatus. When a cart is used, use caution
when moving the cart/apparatus combination to avoid injury from tip-over.
13. Unplug this apparatus during lightning storms or when unused for long periods of time.
14. Refer all servicing to qualied service personnel. Servicing is required when the apparatus has been damaged in any way, such as power supply
cord or plug is damaged, liquid has been spilled or objects have fallen into the apparatus, the apparatus has been exposed to rain or moisture, does
not operate normally, or has been dropped.
15. e plug on the power cord is the AC mains disconnect device and must remain readily operable. To completely disconnect this apparatus from
the AC mains, disconnect the power supply cord plug from the AC receptacle.
16. is apparatus shall be connected to a mains socket outlet with a protective earthing connection.
17. When permanently connected, an all-pole mains switch with a contact separation of at least 3 mm in each pole shall be incorporated in the
electrical installation of the building.
18. If rackmounting, provide adequate ventilation. Equipment may be located above or below this apparatus, but some equipment (like large power
ampliers) may cause an unacceptable amount of hum or may generate too much heat and degrade the performance of this apparatus.
19. is apparatus may be installed in an industry standard equipment rack. Use screws through all mounting holes to provide the best support.
WARNING: To reduce the risk of re or electric shock, do not expose this apparatus to rain or moisture. Apparatus shall not be exposed to dripping
or splashing and no objects lled with liquids, such as vases, shall be placed on the apparatus.
NOTE: is equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules.
ese limits are designed to provide reasonable protection against harmful interference in a residential installation. is equipment generates, uses
and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio
communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful
interference to radio or television reception, which can be determined by turning the equipment o and on, the user is encouraged to try to correct
the interference by one or more of the following measures:
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and receiver.
• Connect the equipment into an outlet on a circuit dierent from that to which the receiver is connected.
• Consult the dealer or an experienced radio/TV technician for help.
CAUTION: Changes or modications not expressly approved by Rane Corporation could void the user's authority to operate the equipment.
CAN ICES-3 (B)/NMB-3(B)
WARNING: is product may contain chemicals known to the State of California to cause cancer, or birth defects or other reproductive harm.

ATTENTION: RISQUE DE CHOCS ELECTRIQUE - NE PAS OUVRIR
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION
An d’éviter tout risque de choc électrique, ne pas ouvrir l’appareil.
Aucune pièce ne peut être changée par l’utilisateur. Contactez un
SAV qualié pour toute intervention.
Les symboles ci-dessous sont reconnus internationalement
comme prévenant tout risque électrique.
Ce symbole indique que cette unité utilise un
voltage élevé constituant un risque de choc
électrique.
Ce symbole indique la présence d’instructions
d’utilisation et de maintenance importantes dans le
document fourni.
ATTENTION
INSTRUCTIONS DE SÉCURITÉ
1. Lisez ces instructions.
2. Gardez précieusement ces instructions.
3. Respectez les avertissements.
4. Suivez toutes les instructions.
5. Ne pas utiliser près d’une source d’eau.
6. Ne nettoyer qu’avec un chion doux.
7. N’obstruer aucune évacuation d’air. Eectuez l’installation en suivant les instructions du fabricant.
8. Ne pas disposer près d’une source de chaleur, c-à-d tout appareil produisant de la chaleur sans exception.
9. Ne pas modier le cordon d’alimentation. Un cordon polarisé possède 2 lames, l’une plus large que l’autre. Un cordon avec tresse de masse possède
2 lames plus une 3è pour la terre. La lame large ou la tresse de masse assurent votre sécurité. Si le cordon fourni ne correspond pas à votre prise,
contactez votre électricien.
10. Faites en sorte que le cordon ne soit pas piétiné, ni au niveau du l, ni au niveau de ses broches, ni au niveau des connecteurs de vos appareils.
11. N’utilisez que des accessoires recommandés par Rane.
12. N’utilisez que les éléments de transport, stands, pieds ou tables spéciés par le fabricant ou vendu avec l’appareil. Quand vous utlisez une valise de
transport, prenez soin de vous déplacer avec cet équipement avec prudence an d’éviter tout risque de blessure.
13. Débranchez cet appareil pendant un orage ou si vous ne l’utilisez pas pendant un certain temps.
14. Adressez-vous à du personnel qualié pour tout service après vente. Celui-ci est nécessaire dans n’importe quel cas où l’appareil est abimé : si le
cordon ou les ches sont endommagés, si du liquide a été renversé ou si des objets sont tombés sur l’appareil, si celui-ci a été exposé à la pluie ou
l’humidité, s’il ne fonctionne pas correctement ou est tombé.
15. La che du cordon d’alimentation sert à brancher le courant alternatif AC et doit absolument rester accessible. Pour déconnecter totalement
l’appareil du secteur, débranchez le câble d’alimentation de la prise secteur.
16. Cet appareil doit être branché à une prise terre avec protection.
17. Quand il est branché de manière permanente, un disjoncteur tripolaire normalisé doit être incorporé dans l’installation électrique de l’immeuble.
18. En cas de montage en rack, laissez un espace susant pour la ventilation. Vous pouvez disposer d’autres appareils au-dessus ou en-dessous de celui-
ci, mais certains (tels que de gros amplicateurs) peuvent provoquer un buzz ou générer trop de chaleur au risque d’endommager votre appareil et
dégrader ses performances.
19. Cet appareil peut-être installé dans une baie standard ou un chassis normalisé pour un montage en rack. Visser chaque trou de chaque oreille de
rack pour une meilleure xation et sécurité.
ATTENTION: an d’éviter tout risque de feu ou de choc électrique, gardez cet appareil éloigné de toute source d’humidité et d’éclaboussures quelles
qu’elles soient. L’appareil doit également être éloigné de tout objet possédant du liquide (boisson en bouteilles, vases,…).
REMARQUE: Cet équipement a été testé et approuvé conforme aux limites pour un appareil numérique de classe B, conformément au chapitre 15
des règles de la FCC. Ces limites sont établis pour fournir une protection raisonnable contre tout risque d’interférences et peuvent provoquer une
énergie de radiofréquence s'il n'est pas installé et utilisé conformément aux instructions, peut également provoquer des interférences aux niveaux
des équipements de communication. Cependant, il n'existe aucune garantie que de telles interférences ne se produiront pas dans une installation
particulière. Si cet équipement provoque des interférences en réception radio ou télévision, ceci peut être detecté en mettant l'équipement sous/hors
tension, l'utilisateur est encouragé à essayer de corriger cette interférence par une ou plusieurs des mesures suivantes:
• Réorienter ou déplacer l'antenne de réception.
• Augmenter la distance entre l'équipement et le récepteur.
• Connecter l'équipement à une sortie sur un circuit diérent de celui sur lequel le récepteur est branché.
• Consulter un revendeur ou un technicien radio / TV expérimenté.
ATTENTION: Les changements ou modications non expressément approuvés par Rane Corporation peuvent annuler l'autorité de l'utilisateur à
manipuler cet équipement et rendre ainsi nulles toutes les conditions de garantie.
CAN ICES-3 (B)/NMB-3(B)
Cartons et papier à recycler.

Manual-1
OPERATORS MANUAL MA3
MULTICHANNEL AMPLIFIER
Quick Start
Sure, you say, “it’s just a three channel amp, I'm in a hurry —
I don't need to read the manual.” But at least read this little sec-
tion so you really know what to expect, and your installation can
go even faster.
Be sure the amplier is o before making any connections.
Euroblocks make amplier connection easy. ey are just like
“snap on” terminal blocks that take up to 12 guage wire.
Driving the MA3 from a balanced source is recommended.
If you must drive the MA3 Input with an unbalanced source, we
recommend using a cable that has two conductors plus a shield,
and be sure to keep cable lengths as short as possible (under 10
feet [3 meters]). See the RaneNote, “Sound System Interconnec-
tion” (contained in this booklet).
Nominal speaker loads should be no lower than 4Ω per out-
put. If you are running series or parallel combinations, be sure
and check your total load impedance.
For constant-voltage distribution, consider using the op-
tional TF410 or TF407 transformers with the MT6 rack panel.
Transformers may be used on any number of output channels re-
quired, and one MT6 can be used with two MA3s. If you intend
to use constant-voltage distribution transformers, you may want
to read the RaneNote “Constant-Voltage Audio Distribution
Systems” (contained in this booklet).
If you are using small speakers that could overload with bass,
you may want to activate an internal 80 Hz Filter on each chan-
nel. e MA3 is shipped from the factory with the jumpers in
the “no lter” position, as shown in the diagram on page 4.
Once Input and Output connections are completed, be sure
all rear panel LEVEL controls are all the way counterclockwise.
Now ip the POWER switch on. After a couple of seconds,
slowly turn up each channels’ LEVEL control to the desired
gain. Maximum yields the most eective dynamic range control
for the built-in Limiter). If all is well, you will hear something
pleasant. If not, re-check connections, put on a better CD, and
read more of this manual.
WEAR PARTS: is product contains no wear parts.
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MA3
MULTICHANNEL
AMPLIFIER
3
CHANNEL OUTPUT HEADROOM
POWER
POWER
Speaker Connection
To reduce the risk of re, follow these instructions:
• Connect speaker wires with the amplier o.
• Use approved Class 2 wiring to connect speakers to the output
terminals.
• e recommended wire gauge is 12-18 AWG.
• Do not use damaged wires, and protect wires from damage.
• Strip wire 0.25 inch (about 6.3 mm).
• Twist the strands together.
• Fully insert the wire into the Euroblock connector.
• Tighten the screw.
• Make certain there are no loose wire strands.
• Use speakers with a power rating equal to or greater than the
rating of the amplier.
• Connection at the speaker depends on the type of connector.
Follow the instructions provided by the speaker manufacturer.

Manual-2
Front Panel Description
1Heat tunnel exhaust vents are located on the left of the unit. Large aperture vent slots are used for low noise. Air is taken in at
the back of the unit and exhausts out the front. When installed in a rack, make sure there is ample room for air to exit. e sealed
heat tunnel design does not require the use of an air lter.
2CHANNEL OUTPUT HEADROOM meters indicate the amount of remaining headroom (how much more signal can be ap-
plied before Limiting occurs).
0 dB remaining is indicated by a red indicator. When lit, any additional signal causes the Limiter to operate. It is possible to “com-
press” the signal as much as 20 dB with very little eect on sound quality. is gives the MA3 the overload characteristics of a
much larger amplier, without the use of external compressors. e MA3 was designed to be driven hard (heavily compressed
signal) so it is not necessary to buy extra power to obtain the headroom required to prevent overload.
3 dB remaining is indicated by a yellow indicator. When lit, 3 dB of additional signal may be applied before Limiting.
6 dB remaining is indicated by a green indicator. When lit, 6 dB of additional signal may be applied before Limiting.
12 dB remaining is indicated by a green indicator. When lit, 12 dB of additional signal may be applied before Limiting.
3POWER: is yellow indicator lights when power is applied to the unit. See 4below.
4POWER switch: is control obediently turns the MA3 on and o every time you poke it with your nger. Poking the top half
of the switch turns the unit on when it is o. Poking the bottom portion of the switch turns the unit o when it it on. All three
channels have turn-on and turn-o muting to reduce switching transients.
21 3 4
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MA3
MULTICHANNEL
AMPLIFIER
3
CHANNEL OUTPUT HEADROOM
POWER
POWER

Manual-3
Rear Panel Description
1INPUTS are balanced Euroblock connectors, one for each channel. We recommend the use of at least 18 AWG wire for reliability.
Driving the MA3 from a balanced source is recommended. If you must drive the MA3 Input with an unbalanced source, use a
cable that has two conductors plus a shield. Connect the (+) or “hot” source to the MA3 (+) Input, the ground to the MA3 (–)
Input and connect the shield to the MA3 shield input. Do not connect the shield on the source end. Shield connections go directly
to chassis ground and should not be used as signal ground. Shield connection to chassis occurs via the screw found between the
Input and Output connectors—keep this screw tight for improved EMI protection. When operating the MA3 with unbalanced
Inputs, be sure to keep cable lengths as short as possible. Refer to the RaneNote “Sound System Interconnection” (included in this
booklet) for additional information.
2LEVEL controls adjust the input sensitivity for each of the three Ampliers. e internal Limiters have maximum operating range
(most amount of limiting before input overload) when the LEVEL controls are set to maximum. For best system noise perfor-
mance, the input sensitivity may be reduced to send a “hotter” signal to the Amplier. Here we go again! You get nothing for free.
ere are always tradeos to be made (better overdrive capability or lower system noise). e choice depends on your application.
For additional information see the RaneNote “Setting Sound System Level Controls” available in the Library on our website.
3OUTPUTS: Connect the speaker(s) or transformer(s) to each of the three channels by means of the Euroblock connectors with 12
to 18 AWG wire. See Speaker Connection on page Manual-1.
4 IEC cord socket: is connector accepts a standard IEC 3-conductor line cord (included with 120V units). Plug this into a
grounded 3-prong AC outlet of 120 VAC (or 230 VAC if the MA3 is internally wired for 230V operation).
5Heat tunnel air intake: e fan draws air in through the nger guard on the rear of the unit. e air ow is directed down a
sealed heat tunnel and exhausts through front panel vents. No lter is required as air ow is directed through an unobstructed
sealed tunnel and will not contaminate internal circuitry.
OUTPUT POWER
PER CHANNEL
40 WATTS / 8Ω
60 WATTS / 4Ω
12-18 AWG
CLASS 2 WIRING
LEVEL
+
-
+
-
+
+
+
+
-
-
-
-
+
+
+
-
-
-
+
-
+
-
+
-
10
0
LEVEL
LEVEL
10
0
10
0
MA3
RANE CORPORATION
WARNING
TO REDUCE THE RISK OF FIRE OR ELECTRICAL SHOCK DO
NOT EXPOSE THIS EQUIPMENT TO RAIN OR MOISTURE. DO
NOT REMOVE COVER. NO USER SERVICEABLE PARTS
INSIDE. REFER SERVICING TO QUALIFIED PERSONNEL.
AVIS
RISQUE DE CHOC ELECTRIQUE — NE PAS OUVRIR
CH 3
CH 2
CH 1
OUTPUTS
INPUTS
CHANNEL 1
CHANNEL 2
CHANNEL 3
120 V
50/60 Hz 360 WATTS
COMMERCIAL AUDIO
EQUIPMENT 24TJ
R
34 21 5

Manual-4
80 Hz Highpass Filters
Internal jumpers allow independently selecting 80 Hz,
2nd-order Butterworth Filters for each channel. ese Filters are
useful when using small bookshelf speakers or small constant-
voltage distribution transformers.
e MA3 is shipped from the factory with the jumpers in the
“no lter” position, as shown in the diagram below. Moving the
jumper to the other position activates the 80 Hz lter. is op-
eration requires removing the top cover and should only be done
by qualied service personel with the unit unplugged.
©Rane Corporation 10802 47th Ave. W., Mukilteo WA 98275-5000 TEL [phone] FAX [phone] WEB rane.com
TF410 & TF407 Transformers
e MT6 rack panel holds up to six transformers installed on the
back, in any combination. Transformers are sold individually:
• e TF407 is a 40W, 70.7 V transformer with 0.5 dB insertion
loss at rated power and a frequency response of 50 Hz to 15
kHz, ±1 dB.
• e TF410 is a 40W, 100 V transformer with 0.5 dB insertion
loss at rated power and a frequency response of 50 Hz to 15
kHz, ±1 dB.
The MA3 is shipped with the internal 80 Hz High-
pass filters in the bypassed position.
DISTRIBUTED DISTRIBUTED DISTRIBUTED
70 V 70 V 70 V
ZONE 3
ZONE 2
ZONE 1
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MA 3
MULTICHANNEL
AMPLIFIER
3
CHANNEL OUTPUT HEADROOM
POWER
POWER
MT 6
MULTICHANNEL
TRANSFORMER
TF 410
LEFT RIGHT ZONE 2
OR
ZONE 1
OR
MONOMONO
EXPAND
8 Ω8Ω 70 V
DISTRIBUTED
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00
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dB
MA 3
MULTICHANNEL
AMPLIFIER
3
CHANNEL OUTPUT HEADROOM
POWER
POWER

Data Sheet-1
MA3
MULTICHANNEL AMPLIFIER
General Description
e MA3 is a three-channel amplier designed to operate reliably
in commercial environments. e MA3 was specically designed
for use in:
• Paging
• Foreground Music
• Background Music Distribution
e MA3 is an ideal amplier with Rane’s paging and music
products, the Rane CP52S, CP64S, CP66 and DA26S.
e MA3 uses a conventional linear power supply with a toroi-
dal transformer. is conguration minimizes the emissions as-
sociated with switching supplies and noisier transformer designs.
e power supply features independent secondary supplies for each
channel, minimizing load regulation interaction and crosstalk.
ermal management is accomplished with a sealed heat-tun-
nel design incorporating low velocity forced-air and large aperture
openings. is design minimizes the noise usually associated
with forced-air cooling and eliminates the need for an air lter.
Forced-air cooling allows the amplier to operate reliably in harsh
environments and avoid the buildup of heat in unventilated racks
associated with passive convection cooling.
e combination of a solid, conservative power supply and
forced-air cooling allows the MA3 to simultaneously deliver 40
watts of continuous average power into 8 and 60 watts into 4.
SPiKe®* dynamic protection circuitry completely safeguards
each channel against over-voltage, under-voltage, overloads,
transients from inductive loads, thermal runaway and instanta-
neous temperature peaks. Biasing is not allowed to occur when
an under-voltage condition exists, reducing turn on and turn o
transients.
Fast-response limiters allow the MA3 to tolerate up to 20 dB of
overdrive into 8 and 4 loads while holding THD below 1%.
is means no loss of speech intelligibility or harsh clipping. is
feature greatly increases the dynamic range of the system without
external limiters.
Peak-responding, load-adaptive meters accurately indicate the
remaining headroom. e meters are helpful in setting system
levels and indicating signal compression.
Balanced inputs with Euroblock connectors are provided. Eu-
roblock output connectors to speakers accept up to 12 gauge wire.
Rear panel Level controls allow amplier sensitivity adjustment.
Internally selectable 80 Hz highpass lters for each channel oer
protection against over excursion of small bookshelf speakers and
saturation of distribution transformers at low frequencies. ese
lters are shipped in the “o” position from the factory.
Features
• 3 Independent Ampliers
• 60W per Channel Continuous Average Power into 4Ω, 20-20k Hz
• 40W per Channel Continuous Average Power into 8Ω, 20-20k Hz
• Load Sensitive Dynamic Limiters and Headroom Meters
• SPiKe®Protection Circuitry
• High Capacity Linear Power Supply
• Sealed Heat-Tunnel Forced Air Cooling
• Input Level Controls (on rear panel)
• 80 Hz High-Pass Filter Selection
• Euroblock Connectors
*SPiKe is a registered trademark of National Semiconductor Corporation.
DATA SHEET

MA3
MULTICHANNEL AMPLIFIER
Data Sheet-2
Features and Specifications
Parameter Specication Limit Units Conditions/Comments
Input: Euroblock Connector
Impedance 20k min.  Each leg
Maximum Input Level +20 min. dBu
Sensitivity O to 0 dBu Input required for full power; 8
CMR 40 min. dB 20 Hz to 20 kHz
Highpass Filter 80 Hz (factory default is “o”) ±2.5% Hz 2nd-order butterworth
Amplier: Gain 27 ±0.5 dB 1 kHz
Power Output 40/60 min. watts 8/4  cont. avg. power, all channels driven
Frequency Response 20 - 20k Hz +0, -.5 dB
S/N 90 min. dBr re: 40W, 8, A-weighted
Crosstalk -60 max. dB 1 kHz, 4, all channels driven
THD+N 0.05% typ. 1 kHz, 40 W, 8, 80 kHz BW
0.1% typ. 1 kHz, 60 W, 4, 80 kHz BW
0.2% typ. 20 Hz-20 kHz, 35W, 8, 80 kHz BW
Slew Rate 10 min. V/s
Damping Factor 80 min. 8, 1 kHz
On/O Transient Muting Active Drop out 85 VAC (120 VAC unit)
Fan Cooling Active Constant-Current Sealed tunnel
Fan Noise 45.2 dB A-weighted, 6 inches from front of fan grate
Tunnel Power Dissipation 120W; 410 Btu/hr 60W / channel; 4 load; all channels driven
SOA SPiKe* Safe Operating Area
Limiter: Attack Time 10 typ. ms 10 dB step
Decay Time 3000 typ. ms 10 dB step
reshold 0.1% THD+N typ. @1 kHz
Action 1% THD+N max. 15 dB overdrive (max. level) @ 1 kHz
Meter: Attack Time 20 typ. ms 10 dB step
Decay Time 500 typ. ms 10 dB step
Indicators 0, 3, 6 ,12 +0, -2 dB 20log (Vmax/Vout) or 10log (Pmax/Pout)
Power Supply: Type Linear; Toroidal Transformer Independent secondaries for each channel
..........Input 100 to 240 VAC ±10% VAC C14 inlet uses C13 cord
..........Consumption 33.6W; 115 Btu/hr No load (idle)
..........Total Load & Unit 360W; 1200 Btu/hr 60 W/channel; 4 load; all channels driven
Unit: Conformity FCC, UL
..........Construction All Steel
..........Size 3.5"H x 19"W x 9"D (2U) (8.9 cm x 48.3 cm x 22.9 cm)
..........Weight 26 lb (11.8 kg)
Shipping: Size 4.25" x 20.3" x 13.75" (11 cm x 52 cm x 35 cm)
..........Weight 30 lb (13.6 kg)
Note: 0 dBu = 0.775 Vrms. *SPiKe is an acronym for Self Peak Instantaneous temperature (Ke) protection circuitry.

Data Sheet-3
MA3
MULTICHANNEL AMPLIFIER
Block Diagram
80 Hz HP
IN
OUT
SERVO
LIMIT
CH 1 LEVEL
MUTE
AMP
VCA
0 dB
3 dB
6 dB
12 dB
HEADROOM METER
CH
1 INPUT
CH 1 OUTP
UT
40 W/8 Ω
60 W/4 Ω
THD+N(%) & LEVEL(W) vs AMPL(dBu) 31 MAR 98 08:52:13
0.02
0.1
1
2
10
15
20
25
30
35
40
45
50
55
60
-5 0 5 10 15 20
Input Level in dBu
Output Power in Watts
THD & Noise in %
Power
THD & Noise
Features
Built to be driven hard
e MA3 Amplier drives all three channels at the continuous
average rated power, indenitely. It is specically designed to
operate in demanding commercial applications. Very low emis-
sions allow the amplier to operate in close proximity to signal
processing equipment without causing excessive interference. e
CP52S, CP64S, CP66 and DA26S may all operate next to the
MA3 in a rack. e high eciency “heat tunnel” design allows
the amplier to process severely compressed signals reliably even
when installed in a rack with elevated ambient temperatures.
Forced-air cooling keeps heat away from other equipment.
You won't hear the other Zones
e MA3 is designed to deliver foreground music, background
music and paging signals to three dierent Zones without an-
noying crosstalk. A quiet oce, for example, with a paging signal
only, will not hear foreground music playing in the lounge. e
high capacity linear power supply incorporates three independent
secondary supplies with independent bridge rectiers and lters.
e result is exceptionally good crosstalk gures even with mul-
tiple channels driving full power into 4 loads.
No bad “spikes”
e MA3 is designed to operate without interruption of signal
with as little as 85 VAC available (120 VAC unit). Even if the
Amplier is operating at full power, the signal will not breakup as
the AC line voltage drops to 85 VAC. If the AC line drops lower
than 85 VAC the signal mutes without “spikes.” Once AC power
is restored, the signal restarts quickly without “spikes” or signal
breakup.
The good “SPiKe”
e power ampliers in the MA3 are protected with National
Semiconductors’ proprietary SPiKe* protection circuitry. SPiKe
protection oers a level of protection not available in conven-
tional ampliers. It has the ability to instantaneously monitor the
temperature of the power device die, yielding a level of reliability
not achievable with discrete designs.
It’s OK to light the 0 dB Headroom indicator a lot
e high-performance limiter used in the MA3 means all the
available power can be delivered to the load and not simply held
in reserve to avoid overload. ere is no need to buy up to four
times the required power just to prevent occasional system over-
load. e MA3 can compress a signal with 9 dB of dynamic power
range down to a signal with 3 dB of dynamic power without loss
of speech intelligibility or excessive distortion.
With typical ampliers, when 40 watts is needed to achieve
a required average SPL of 80 dB, the contractor must buy an
amplier rated at no less than 160 watts just to maintain 6 dB
of headroom. e gure below illustrates the performance of the
MA3 limiter.
Channel 1 shown, other two channels are identical
*Spike is a registered trademark of National Semiconductor Corporation.
SPiKe is an acronym for Self Peak Instantaneous (Ke) protection circuitry.

MA3
MULTICHANNEL AMPLIFIER
Data Sheet-4 All features & specications subject to change without notice. 11-2014
Rear Panel
©Rane Corporation 10802 47th Ave. W., Mukilteo WA 98275-5000 USA TEL [phone] FAX [phone] WEB rane.com
MT6 Transformer Panel
Constant-voltage transformers may be purchased individually,
and up to six may be mounted in any combination on the back of
a 2U high MT6 rack panel:
• TF407 is a 40W, 70.7V Distribution Transformer
• TF410 is a 40W, 100V Distribution Transformer
Both transformers rated at 40 watts, 50 Hz to 15k Hz ±1 dB,
with 0.5 dB insertion loss. Each transformer comes with crimp-
on tabs, wire nuts, and mounting screws.
For applications, see the RaneNote “Constant-Voltage Audio
Distribution Systems: 25, 70.7 & 100 Volts.”
Architectural Specifications
e MA3 shall be a three channel amplier. It shall deliver
40 watts continuous average power into 8 ohms and 60 watts
continuous average power into 4 ohms. e amplier shall have
balanced inputs with Euroblock connectors and Euroblock
output connectors capable of accepting 12 gauge wire. Input level
controls shall allow adjustment of input sensitivity. An internal
means of selecting 80 Hz highpass 2nd-order butterworth lters
shall be provided. Load sensitive limiter circuits shall expand the
dynamic range of the ampliers and prevent clipping and the as-
sociated loss of speech intelligibility.
e power supply shall use a conventional linear supply with
means of operating from 120 VAC 50/60 Hz or 230 VAC 50
Hz. An IEC connector with integral fuse and IEC cord shall be
utilized. A front panel mounted power switch shall be provided
with a “power-on” indicator.
ermal management shall employ forced air cooling, allowing
the ampliers to operate reliable in unventilated racks at elevated
ambient temperatures. e design shall incorporate a sealed heat
tunnel with large aperture openings and low velocity air ow to
minimize noise and eliminate the need for air ltering and the
associated maintenance.
e design shall provide protection against overvoltage,
undervoltage, overloads, transients from inductive loads, thermal
runaway and instantaneous temperature peaks. Load sensitive
headroom meters shall provide indication of 0, 3, 6 and 12 dB of
remaining headroom.
e main chassis shall be constructed of 12 gauge, cold- rolled
steel capable of reliably supporting rack mount applications. e
unit shall be UL listed and cUL certied.
e unit shall be a Rane Corporation model MA3.
MT 6
MULTICHANNEL
TRANSFORMER
MT6 front panel
MT6 rear panel with six transformers installed.

MT6
MULTICHANNEL TRANSFORMER KIT
DATA SHEET
General Description
e MT6 is simply a 2U rack panel that can mount up to six
distribution transformers for Rane MA3 ampliers.
Constant-voltage transformers are purchased individually:
• TF407 is a 40W, 70.7V Distribution Transformer
• TF410 is a 40W, 100V Distribution Transformer
Both transformers rated at 40 watts, 50 Hz to 15k Hz ±1 dB,
with 0.5 dB insertion loss. e transformer wires have insulated
female tabs. To accomodate dierent installation preferences,
each transformer includes:
• Four insulated crimp-on male tabs
• Four wire nuts
• Two mounting screws and nuts for the MT6 plate.
For applications, see the RaneNote “Constant-Voltage Audio
Distribution Systems: 25, 70.7 & 100 Volts.” available at rane.
com.
MT 6
MULTICHANNEL
TRANSFORMER
Front Panel
Rear Panel
MT6 Specifications
Parameter Specication Limit Units Conditions/Comments
Unit: Panel Construction 12 gauge steel
..........Size: 2U 3.5"H x 19"W 8.89 cm x 48.26 cm
Shipping Weight 3 lb 1.36 kg

TF407 Specifications
Parameter Specication Limit Units Conditions/Comments
Transformer Rating 40 Watts Maximum average power
..........Connectors 0.187" Female Insulated Terminal Includes male tabs and wire nuts
..........Wire 10" length inch U.L., C.S.A., 90C grade
Output Tap: Voltage 70.7 Vrms
Frequency Response 50 Hz to 15 kHz ±1 dB 8Ω
Insertion Loss .5 typ dB
Shipping Weight 3 lb 1.36 kg
All features & specications subject to change without notice. PN 16910
©Rane Corporation 10802 47th Ave. W., Mukilteo WA 98275-5000 USA TEL [phone] FAX [phone] WEB rane.com
TF410 Speci fications
Parameter Specication Limit Units Conditions/Comments
Transformer Rating 40 Watts Maximum average power
..........Connectors 0.187" Female Insulated Terminal May be removed to use wire nuts
..........Wire 10" length inch U.L., C.S.A., 90C grade
Output Tap: Voltage 100 Vrms
Frequency Response 50 Hz to 15 kHz ±1 dB 8Ω
Insertion Loss .5 typ dB
Shipping Weight 3 lb 1.36 kg
BLACK
RED
BLACK
WHITE
8 Ω
Fr
om amplier outputs 70.7 VOLT LINE to loudspeakers
BLACK
RED
BLACK
WHITE
8 Ω
Fr
om amplier outputs 100 VOLT LINE to loudspeakers
MT6
MULTICHANNEL TRANSFORMER KIT
WARNING: is product may contain chemicals known to the State of California to cause cancer, or birth defects or other reproductive harm.

Distribution Transformers-1
Unwinding Distribution
Transformers
• High Voltage Audio Distribution
• Transformers at the Power Amp End
• Turns Ratio
• Saturation
• Insertion Loss
• Transformers at the Loudspeaker End
• Impedance Matching
• Isolation
Paul Mathews
Rane Corporation
RaneNote 159
© 2005 Rane Corporation
RaneNote
UNWINDING DISTRIBUTION TRANSFORMERS
Introduction
What could be more mundane than the transform-
ers and autoformers that are the backbone of audio
distribution systems? is article will show you that
there is a lot more going on with these chunks of iron
and copper than you ever suspected. Learn why trans-
formers are often the power bottleneck in distribu-
tion systems, learn how to interpret datasheets, believe
or disbelieve manufacturers’ claims, how to specify HV
components, and how to setup HV systems to deliver
the best possible power, fidelity, and bandwidth.
High Voltage Audio Distribution Systems
Although the term Constant Voltage is still in com-
mon use, this article adopts the less confusing High
Voltage (HV) terminology. HV systems are in wide-
spread use for these principal reasons:
•HV systems minimize power losses in low-cost
wiring.
• HV systems facilitate connection of multiple loud-
speakers without careful consideration of impedance
matching.
•Once an individual power adjustment on a loud-
speaker has been made, the loudspeaker continually
receives the same amount of power even when other
loudspeakers are added or removed from the system,
resulting in more constant and uniform coverage.
•Volume control by transformer tap at the loudspeak-
er end is more efficient than resistive pads.

Distribution Transformers-2
Transformers at the Power Amp End
Boosting the Output Voltage
Solid state power amplifiers usually need a volt-
age boost to get to the 70.7 volt and 100 volt levels of
most HV systems, and a transformer or autoformer
will do the job. e differences between transform-
ers and autoformers will be covered later (see the To
Isolate or Not to Isolate? section). In the meantime, the
term transformer will be used to refer to both types.
e transformer boosts the amplifier output by a fixed
ratio, called its turns ratio. e correct transformer will
provide the right amount of boost, which is simply the
desired HV system voltage, e.g., 70.7 volts, divided by
the amplifier full power output voltage.
Here is the basic procedure for selecting an output
transformer for an HV system where the amplifier
power required P has been determined using suitable
methods:
1. Determine TURNS RATIO to get proper HV level.
a) Measure the unclipped rms output voltage avail-
able from the power amplifier or calculate if from
Ohm’s Law:
VOUT = √P x R
For example, for an amplifier rated 100 watts at 8Ω:
VOUT = 28.3 Vrms
b) Calculate desired voltage boost ratio, aka turns
ratio,
N = VHV / VOUT, e.g., N = 70.7 / 28.3 = 2.5
Select candidate transformers with turns ratio
within 20% of calculated N and with datasheet
power ratings similar to amplifier output wattage.
2. Determine TRANSFORMER SIZE to prevent saturation.
a) VERY IMPORTANT: Decide on the lowest sys-
tem frequency fLC for good fidelity and full power
delivery.
b) Find datasheet ratings or conduct tests to deter-
mine voltage tolerance of candidate transformers at
fLC.
c) To qualify, a transformer must not saturate when
driven with VOUT at fLC. You may or may not be able
to determine this characteristic from datasheets.
Read on.
e low frequency voltage capabilities of the
transformer will be the primary limiting
factor in system power delivery.
TURNS RATIO: Finding It on the Datasheet
Turns ratio does not show up on many datasheets,
but you can usually calculate it from other specifica-
tions. From the information on a transformer data-
sheet, find any combination of specifications that
relates primary voltage, or primary power and imped-
ance, to secondary voltage. Use these equations, based
on Ohm’s Law and Joule’s Law, to calculate the missing
specification.
VPA = √P x R VHV = N x VPA N = ——
For example, from transformer datasheet specs
showing “300 watts at 4Ω” (amplifier/primary side) and
“70.7V output” (secondary), use the first equation to
calculate power amp output voltage VPA = 34.6V. en,
use the third equation to calculate
N = 2.04.
Some transformers have what their datasheets call
voltage taps. For example, a transformer might have 25
volt, 35 volt, and 45 volt primary taps, along with 70.7
volt and 100 volt secondary taps. For any combination
of primary and secondary taps, the effective turns ratio
is simply the ratio of the secondary tap value to the
primary tap value, as given in the third equation above.
Now that we have the Turns Ratio (Step 1 above),
let’s look at the other most important performance
determining characteristic, which is voltage capability,
usually determined by transformer size and weight.
SATURATION: What’s All the Flux About?
Transformers have saturation problems that limit
their capabilities at low frequencies. In fact, a trans-
former that is doing a great job at 100 Hz can be an
amplifier killer just an octave lower. What happens
when a distribution transformer saturates? What does
saturation sound like? Does this mean you have to high
pass all your HV systems? ese and other questions
are answered here.
VHV
VPA

Distribution Transformers-3
What Happens When a Transformer Saturates?
Transformers transfer power from winding to wind-
ing by coupling through mutual magnetic fields. is
transfer of power is amazingly efficient, and it happens
with or without a core. However, the iron core plays
two essential roles:
1. e core contains the magnetic fields. Without a
core, significant portions of the magnetic fields bal-
loon out around the windings, reducing mutual cou-
pling and potentially causing interference problems.
2. e magnetic field in the core itself opposes un-
coupled current flow in the primary. is is why
the transformer primary, even though it is made
of heavy copper wire, does not normally act like a
short.
Without a core, the primary does act like a short, and
a saturated core is not much better than no core.
is what happens when the applied voltage polarity re-
mains the same for too long.
Saturation has nothing to do with power delivery:
the onset of saturation depends only on the
voltage waveform applied to the primary.
To reinforce this point, the next graphic shows am-
plifier voltage and current with an unloaded (open cir-
cuit) secondary. e current waveform stays near zero
until the volt-seconds limit of the primary is reached.
Here are the primary voltage (top) and current (bot-
tom) oscilloscope traces for a distribution transformer
entering saturation toward the end of each half cycle
of input. Both waveforms should be sinusoidal, but
the spikes on the current waveform are due to satura-
tion. Notice that the power amplifier, in this case, is
still doing a good job of delivering a sine wave, in spite
of the current spikes. A less-robust power amplifier
would show noticeable distortion coinciding with each
spike. e coupling between primary and secondary is
not much affected by core saturation. However, during
saturation, the dc resistance of the primary suddenly
appears in parallel. e power amplifier tries to main-
tain its output voltage, but the load impedance has
taken a sudden dive.
Core saturation happens when the magnetic field in
the core reaches its maximum possible density, which
For audio signals, core saturation is more likely as
you lower the frequency and raise the applied voltage.
In the preceding photo, the input was 20 Vrms at 25
Hz. e onset of saturation depends on voltage and
time, so expect to see a similar problem for 40 Vrms
and 50 Hz.
e saturation voltage of a transformer rises
linearly with frequency. is means that
power handling capability declines with
the inverse square of the frequency.
It should be no surprise that DC voltages are a seri-
ous problem for transformers, since DC is like zero
frequency. Indeed, dc offsets of a few tens or hundreds
of millivolts can asymmetrically saturate a trans-
former, meaning that saturation current spikes will
occur primarily on one signal polarity. For this reason,
some power amplifiers are a poor match to distribution
transformers, is is also one reason why some manu-
facturers recommend installing resistors and capaci-
tors in series with distribution transformers, further
impacting low frequency response. Well-designed
power amplifiers have low offsets, and well-designed
transformers tolerate a reasonable level of offset.

Distribution Transformers-4
The Sound of Saturation
When power amplifiers suddenly finds itself having
to deliver massive amounts of current, most will pro-
tect themselves by throttling back their output voltage.
On the better amplifiers, Safe Operating Area (SOA)
circuitry kicks in. On less well-designed units, the
internal power supply voltages collapse, and the ampli-
fier circuitry is simply unable to continue to deliver a
faithful signal. Some amplifiers may blow fuses or sim-
ply fail. e sound that you hear depends very much
on how a particular amplifier responds to this type of
overload. Most likely, you will hear badly distorted bass
and/or signal drop-outs.
Size Matters
As with most things audio, you need larger com-
ponents to handle lower frequencies, and the same is
true for transformers. If other design elements are held
constant, the larger cores can tolerate higher primary
voltage levels, because magnetic fields produce lower
flux densities over their larger cross-sectional areas.
Another way to improve the voltage capability of a
transformer is to increase the number of turns in each
winding. However, unless the wire size is made smaller
(resulting in higher resistive losses), the core may still
have to be made larger to accommodate the additional
turns of wire.
Many of the distribution transformers we tested would
have much improved performance if their designers
had simply added a few turns of wire to their design.
Where Does It Say Saturation on the Datasheet?
Unfortunately, most transformer datasheets are not
much help in providing specifications for low fre-
quency performance. Some provide a vague ‘Frequency
Response’ range. Our tests indicate that this is usu-
ally hopelessly optimistic if not dishonest: the power
bandwidth at the low end is generally much lower than
the specification. Fortunately, since no secondary load
is required to observe saturation, bench measurements
are easy. Connect a sinewave source to the primary
with a small-value resistor in series. Measure the rms
voltage across the primary with a voltmeter or an
oscilloscope. Similarly measure the voltage across the
resistor. Start at 1 kHz and sweep downwards. Across
the resistor, you should measure a small voltage (pro-
portional to primary current) that increases slowly as
you decrease frequency. At some frequency, you will
observe an abrupt increase in resistor voltage, indica-
tive of the onset of saturation. Change the drive volt-
age and repeat the sweep. You should be able to derive
a graph like the one shown here. is particular ‘300
watt’ transformer has a datasheet indicating “Frequen-
cy Response: 20 Hz to 20 kHz.” How would you rate it?
"300 watt" Transformer Power Handling vs Frequency
10
100
1000
20 70 120 170 220
Frequency (Hz)
Power (W)
Pmax for THD = 0.1% Rated P
What About High Frequencies?
From the discussion about low frequencies and satu-
ration, you have probably guessed that saturation is not
a problem at high frequencies. However, other non-ide-
al characteristics come into play. Stray magnetic fields,
uncoupled between primary and secondary, show up as
leakage inductance in series with the windings. Leak-
age inductance reduces the voltage available to the load
at higher frequencies. Core losses are another phenom-
enon affecting high frequencies. e better cores use
more expensive steels and thinner laminations. Data-
sheet specifications are reasonably reliable indicators of
high frequency performance.
Toroidal (at right in photo) types of transform-
ers tend to have lower leakage inductance and better
high frequency performance than most E-core models
(at left in photo). However, excellent performance is
available from either type of core: it all depends on the
details of the design.

Distribution Transformers-5
What About Insertion Loss?
Insertion loss seems to be a mandatory specification
for distribution transformers, although we find it diffi-
cult to understand why. Losses in loudspeakers them-
selves totally dominate most audio systems, and audio
power is easy to find and cheap to buy. It is almost
impossible to overheat even very lossy distribution
transformers with audio program material: there is just
too much iron, copper, and surface area in a transform-
er that is large enough to couple at low frequencies, and
average audio power is so much lower than the peaks
that the transformer must accommodate. Finally, the
winding resistance that causes insertion loss can be a
desirable feature, since it improves the transformer’s
tolerance for DC offsets.
Insertion loss is not useful as distribution
transformer specification. Instead, focus on the
a transformer’s ability to deliver power at the
highest and lowest required frequencies.
Transformers at the Loudspeaker End
On the secondary side of the power amplifier distri-
bution transformer, we connect HV loudspeakers in
parallel (each with its own step-down transformer),
and adjust power taps as required to achieve required
loudness in each area. System designers usually specify
HV loudspeakers with integral transformers, so you
might suppose that the drivers and transformers are
well-matched, so why worry? It turns out that ten little
10 watt transformers in parallel can be just as trouble-
some as one big 100 watt transformer.
e transformer characteristics discussed
above apply equally at the loudspeaker end.
Loudspeaker Step-down Transformers and Saturation
e transformers at the loudspeaker end are prone to
saturation, just like their big cousins at the amplifier
end. Imagine the effect of 10 or more transformers
all reaching voltage saturation in parallel and at the
same time. Moreover, since saturation depends only
on voltage, each loudspeaker transformer should be
able to withstand full HV voltage levels at the lowest
system frequency, regardless of the amount of power
allocated to it. is is why most HV loudspeaker mod-
ules include a series capacitor to reduce the likelihood
of transformer saturation. Note, however, that these
capacitors are perfectly suited to carrying saturation
current spikes once those spikes begin to flow.
Is Impedance Matching Important?
For best results, adjust loudspeaker taps so that they
sum to either the power amplifier output rating or to
the power amplifier distribution transformer rating,
whichever is smaller. is will present the proper rated
load impedance to the power amplifier, allowing it
to develop rated power, while minimizing saturation
effects in the transformer at low frequencies.
If additional loudspeakers are added or power tap
settings are increased beyond the amplifier or trans-
former rating, load impedance for the power amplifier
will go down proportionately.
However, a smaller but
still linear load impedance is usually the preferred alter-
native to a highly nonlinear saturating transformer.
To Isolate or Not to Isolate?
Distribution transformers are available in both au-
toformer (non-isolating) and transformer (isolating
configurations), so you have the option of isolating the
loudspeaker wiring from the amplifier wiring. Here’s a
couple of reasons why you might want to.
Safety Isolation
Distribution transformers can provide an additional
barrier between lethal mains power potentials and ac-
cessible loudspeaker terminals. HV lines from isolat-
ing transformers have no potential relationship with
respect to earth ground, so that shocks are unlikely
except in the event of contact with both lines at once.
Some electrical inspectors require that HV lines be
isolated from power amplifier outputs.
Isolation to Break Ground Loops
For the many types of audio equipment that have
shielding potentials connected to safety ground, non-
isolated HV loudspeaker lines occasionally provide a
return path for ground loops with enormous extents.
In this era of plastic loudspeaker enclosures, this is
becoming more rare.

Distribution Transformers-6
©Rane Corporation 10802 47th Ave. W., Mukilteo WA 98275-5098 USA TEL [phone] FAX [phone] WEB www.rane.com
DOC 108874
Summary
1. Selecting a Distribution Transformer at the Power Amp End:
a) Select proper turns ratio to boost to HV system level and to present an acceptable impedance to the power
amplifier. You may have to derive turns ratio from other specs.
b) Select for adequate low frequency voltage capability to prevent saturation for good low frequency power
transfer. You may have to make your own measurements.
c) Verify sufficiently low leakage inductance and low core losses for good high frequency power transfer. It’s
usually OK to use datasheet information.
2. Transformers at the Loudspeaker End:
a) Suffer from the same problems and can equally become the weak link in a system.
b) Are often ‘matched’ to and included with loudspeaker modules, so be aware of inherent characteristics.
3.
Toroids versus E-cores: details are more important than shape.
4. Transformer isolation: can improve safety and eliminate ground loops.

Interconnection-1
Introduction
is note, originally written in 1985, continues to be
one of our most useful references. It’s popularity stems
from the continual and perpetual difficulty of hooking
up audio equipment without suffering through all sorts
of bizarre noises, hums, buzzes, whistles, etc.— not to
mention the extreme financial, physical and psycholog-
ical price. As technology progresses it is inevitable that
electronic equipment and its wiring should be subject
to constant improvement. Many things have improved
in the audio industry since 1985, but unfortunately
wiring isn’t one of them. However, finally the Audio
Engineering Society (AES) has issued a standards
document for interconnection of pro audio equip-
ment. It is AES48, titled “AES48-2005: AES standard
on interconnections —Grounding and EMC practices
— Shields of connectors in audio equipment containing
active circuitry.”
Rane’s policy is to accommodate rather than dic-
tate. However, this document contains suggestions for
external wiring changes that should ideally only be
implemented by trained technical personnel. Safety
regulations require that all original grounding means
provided from the factory be left intact for safe op-
eration. No guarantee of responsibility for incidental
or consequential damages can be provided. (In other
words, don’t modify cables, or try your own version of
grounding unless you really understand exactly what
type of output and input you have to connect.)
Rane Technical Staff
RaneNote 110
© 1985, 1995, 2006, 2007, 2011 Rane Corporation
Sound System
Interconnection
• Cause & prevention of ground loops
• Interfacing balanced & unbalanced
• Proper pin connections and wiring
• Chassis ground vs. signal ground
• Ground lift switches
RaneNote
SOUND SYSTEM INTERCONNECTION