McIntosh MC3500 Mono Tube Amplifier Owner’s Manual
- June 4, 2024
- McIntosh
Table of Contents
MC3500
Mono Tube Amplifier
Owner’s Manual
Important Safety Information is supplied in a separate document “Important
Additional Operation Information Guide”
Thank You
Your decision to own this McIntosh MC3500 Tube Power Amplifier ranks you at
the very top among discriminating music listeners. You now have “The Best.”
The McIntosh dedication to quality is assurance that you will receive many
years of musical enjoyment from this unit. Please take a short time to read
the information in this manual. We want you to be as familiar as possible with
all the features and functions of your new McIntosh.
Please Take A Moment
The serial number, purchase date, and McIntosh Dealer name are important to
you for possible insurance claims or future service. The spaces below have
been provided for you to record that information:
Serial Number: ___
Purchase Date: __
Dealer Name: __
Technical Assistance
If at any time you have questions about your McIntosh product, contact your
McIntosh Dealer who is familiar with your McIntosh equipment and any other
brands that may be part of your system. If you or your Dealer need additional
help concerning a suspected problem, you can receive technical assistance for
all McIntosh products at:
McIntosh Laboratory, Inc. 2 Chambers Street
Binghamton, New York 13903
Phone: 607-723-3512
Fax: 607-724-0549
Customer Service
If it is determined that your McIntosh product is in need of repair, you can
return it to your Dealer. You can also return it to the McIntosh Laboratory
Service Department. For assistance on the factory repair return procedure,
contact the McIntosh Service Department at:
McIntosh Laboratory, Inc.
2 Chambers Street
Binghamton, New York 13903
Phone: 607-723-3515
Fax: 607-723-1917
IMPORTANT!
INSTRUCTIONS FOR REMOVAL OF FOAM INSERT OVER THE VACUUM TUBES PRIOR TO
CONNECTING THE A.C. POWER SUPPLY CORD START ON THE NEXT PAGE.
Unpacking the MC3500
WAR NING: To prevent damage to the MC3500 Vacuum Tubes during shipping,
there is a special foam insert surrounding the Vacuum Tubes of the Power
Amplifier. The Foam Insert must be removed from the MC3500 before connecting
the AC Power Supply Cord to the Power Amplifier.
Failure to do so is a Fire Hazard, which could result in damage to the MC3500
and the surrounding environment.
Follow these instructions for the removal of the packing foam before
connecting the AC Power Supply Cord to the MC3500.
In order to remove the foam insert surrounding the Vacuum Tubes on the MC3500,
it is necessary to temporarily remove the Tube Cover. After the foam insert is
removed, the Tube Cover must be reinstalled for the proper and safe operation
of the MC3500 Power Amplifier. The Tube Cover provides protection from the
hazardous voltages inside the MC3500. The MC3500 has no user-serviceable
parts, including the Vacuum Tubes. If repairs are needed, they must be
performed by an authorized McIntosh Service Agency.
-
Orient the MC3500 so the rear of the Power Amplifier is facing you and remove the Warning Sheet. Refer to figure 1.
-
Remove the four screws and the two Hot Surface Tags located on the top of the Tube Cover by using a #2 Phillips Head Screw Driver. Refer to figure 1.
-
Place the Tube Cover, Hot Surface Tags, and screws in a safe location, as the Tube Cover will be reinstalled.
-
Carefully lift up and remove the Tube Cover from the MC3500. Refer to figure 2.
-
Carefully lift up and remove the Foam Insert from the MC3500, exposing the Vacuum Tubes. Refer to figures 3 and 4.
-
Carefully place the Tube Cover back on the MC3500.
-
Place the Hot Surface Tags in the top corners of the Tube Cover. Secure the Cover to the MC3500 Chassis using the four screws. Refer to figure 5.
Note: Save the Foam Insert and Warning Sheet with the MC3500 Shipping Carton for future use.
Ventilation
Adequate ventilation extends the trouble-free life of the MC3500. Always allow
air to flow through the ventilation holes on the bottom of the amplifier and a
means for the warm air to escape at the top. Refer to figure 6.
Allow at least 19 inches (48.3cm) above the top; 6 inches (15.2cm) for the
Front, Rear, and Sides; allow 7/8 inch (2.2cm) below the Power Amplifier so
airflow is not obstructed.
General Information
- For additional connection information, refer to the documentation included with any component(s) connected to the MC3500.
- Apply AC Power to the MC3500 and other components only after all the system components are connected together. Failure to do so may cause a malfunction of system operations as the Microprocessor’s Circuitry inside the components is active when AC Power is applied.
- When discarding the unit, comply with local rules or regulations. Batteries should never be thrown away or incinerated but disposed of in accordance with the local regulations concerning battery disposal.
- For additional information on the MC3500 and other McIntosh Products, please visit the McIntosh Website at www.mcintoshlabs.com.
Connector and Cable Information
XLR Connectors
Below is the Pin configuration for the XLR Balanced Input Connectors on the
MC3500. Refer to the diagram for the connection:
PIN 1: Shield/Ground
PIN 2: + Output
PIN 3: – Output
Power Control Connector
The Power Control Input Jack receives Power On/Off Signals when a component is
connected. The Power Control Output will in turn provide a +12 volt Output
Signal with a current up to 25 mA. An additional connection is for
controlling the illumination of the MC3500 Power Meter when connected to a
compatible McIntosh Preamplifier or A/V Control Center Power Control Output.
A 3.5mm stereo mini phone plug is used for these connections.
Output Terminal Connector
When cables with spade lugs are used for Loudspeaker Connection, the spade
lugs need an opening of at least 3/10 inch (7.6mm) and 3/10 of an inch
(7.6millimeters) Introduction
Now you can take advantage of traditional McIntosh standards of excellence in
the MC3500 Tube Power Amplifier. The 350-watt power output will drive any
high-quality Loudspeaker System. The MC3500 reproduction is sonically
transparent and absolutely accurate. The McIntosh Sound is “The Sound of the
Music Itself.” Performance Features
Power Output
The MC3500 is a Tube Power Amplifier with a capability of 350 watts into 2-,
4-, or 8-ohm Loudspeakers with less than 0.3% distortion. Unity Coupled
Circuitry The MC3500 Power Amplifier uses the famous McIntosh Patented Unity
Coupled Circuit which provides low distortion, extended frequency response,
and cool operating output tubes.
Multifilar Wound Output Transformer
The MC3500 Output Transformer Windings are part of the Unity Coupled
Circuitry. There are three trifilar wound primaries, one for the cathodes, one
for the plates, and one for the screens. The secondary winding is wound
together with the primary windingsThis provides very close primary to
secondary coupling. The result is a flat frequency response and wide power
bandwidth.
Balanced and Unbalanced Input
Balanced connections guard against induced noise and allow long cable runs
without compromising sound quality.
Sentry Monitor Tube Protection
Sentry Monitor provides protection for the MC3500 by monitoring Output. In the
event of a large impedance mismatch, a short circuit at the Output Terminals,
or Tube failure, Sentry Monitor will activate to prevent potentially
destructive levels of current from flowing.
Vacuum Tube Sockets
Small Signal Vacuum Tubes Sockets have Ceramic Base construction with gold-
plated contacts, providing protection from atmospheric contamination. Output
Tube Sockets include Air-Pipe cooling at their bases for long-term operation.
Amplifier Gold Plated Connectors Gold Plated Input Jacks and Output Binding
Posts provide trouble-free connections.
Special Power Supply
A very large core Power Transformer and large filter capacitors ensure stable
operation. Power Guard Screen Grid Sensor (SGS) Power Guard Screen Grid
Sensor™ (SGS) helps prevent premature Vacuum Tube failure by monitoring the
screen grid current in the EL509S output Vacuum Tubes. If the current becomes
too high, a circuit in Power Guard SGS™ is activated which then dynamically
attenuates the input signal in real-time to keep the Vacuum Tubes operating at
safe levels. The right amber LED will flash when Power Guard SGS is engaged
in protecting the Vacuum Tubes.
Dimensions
Navigating the Rear Panel
- Balanced Input: Connect an XLR connector cable (see Page 6) from an external output device into this port to amplify a Balanced signal.
- Unbalanced Input: Connect an RCA connector cable from an external output device into this port to amplify an Unbalanced signal.
- Balanced Output: This port produces a signal from the Balanced Input using an XLR connector cable (see Page 6)
- Unbalanced Output: This port produces a signal from the Unbalanced Input using an RCA connector cable.
- Power Control Out: Sends an On/Off signal to a connected McIntosh component via a 3.5mm cable (see Page 6).
- Power Control In: Receives an On/Off signal from a connected McIntosh component via a 3.5mm cable (see Page 6).
- Input Mode Switch: Switch to toggle between Balanced and Unbalanced Inputs.
- Auto Off: Switch to Enable/Disable Auto Off function.
- Main Power: Connect to a power outlet using the included power cable to supply power to the MC3500
- Fuse Holder: Houses the fuse to power the unit.
- Loudspeaker Terminal Posts: Connect loudspeakers using speaker cable (see Page 10).
Connection Diagram
Connection Legend:
AC Power Cable:
Loudspeaker Cable:
Power Control Cable:
Audio Signal Cable:
How to Connect Loudspeakers
For the best performance and safety, it is important to always match the impedance of the Loudspeaker to the Power Amplifier connections. When connecting the Loudspeaker Hookup Cables to the MC3500 Power Amplifier Output Terminals please follow the steps below:
-
Rotate the top of the Output Terminal Post counterclockwise until an opening appears. Refer to figures A and B.
-
Insert the Loudspeaker hookup cable into the Output Terminal Post opening or the cable spade lug around the center post of the Output Terminal. Refer to figure C.
-
Rotate the top of the Output Terminal Post clockwise until it is finger-tight. Refer to figure D.
-
Place the supplied McIntosh Wrench over the top of the Output Terminal and rotate it one-quarter of a turn (90°) to secure the Loudspeaker Cable Connection. Do not over-tighten. Refer to figure E.
WAR NING: Do not connect the AC Power Cord to the MC3500 Rear Panel until after the Loudspeaker Connections are made. Failure to observe this could result in Electric Shock. The connection instructions below, together with the MC3500 Connection Diagram located on Page 9 is an example of a typical audio system. Your system may vary from this; however, the actual components would be connected in a similar manner. For additional information, refer to “Connector and Cable Information” on Page 6.
-
For Remote Power Control, connect a power control cable from the Audio Preamplifier Power Control Main Output Jack to the Power Amplifier POWER CONTROL IN Jack.
-
Connect XLR cables from the Balanced Main Output connector of the Audio Preamplifier to the Power Amplifier Balanced INPUTS. Place the INPUT Switch in the Balanced Position.
Note: An optional hookup is to use an unbalanced cable and place the INPUT MODE Switch in the Unbalanced Position.Unbalanced Position. This McIntosh MC3500 Power Amplifier is designed for Loudspeakers with an impedance of 2 ohms, 4 ohms, or 8 ohms. Connect a single Loudspeaker only to the Output Terminals. When connecting Loudspeakers to the MC3500 it is very important to use cables of adequate size, so there is little to no power loss in the cables. The size is specified in AWG (American Wire gauge). The smaller the Gauge number, the larger the wire size:
Note: The impedance of a Loudspeaker actually varies as the Loudspeaker reproduces different frequencies. As a result, the nominal impedance rating of the Loudspeaker (usually measured at a midrange frequency) might not always agree with the impedance of the Loudspeaker at low frequencies where the greatest amount of power is required. Contact the Loudspeaker Manufacturer for additional information about the actual impedance of the Loudspeaker before connecting it to the McIntosh MC3500.Loudspeaker Cable Distance vs Wire Gauge GuideLoudspeaker
Impedance| 25 feet
(7.62 meters)
or less| 50 feet
(15.24 meters)
or less| 100 feet
(30.48 meters)
or less
2 Ohms| 12AWG| 10AWG| 8AWG
4 Ohms| 14AWG| 12AWG| 10AWG
8 Ohms| 16AWG| 14AWG| 12AWG -
Prepare the Loudspeaker Hookup Cable for attachment to the MC3500 Power Amplifier: Bare wire cable ends: Carefully remove sufficient insulation from the cable ends, refer to figures 1, 2, and 3. If the cable is stranded, carefully twist the strands together as tightly as possible.
Notes: 1. If desired, the twisted ends can be tinned with solder to keep
the strands together.
2. The prepared bare wire cable ends may be inserted into spade lug connectors.
3. Banana plugs are or se in the United States and Canada only. Banana Plugs are for use in the United States and Canada only: -
Attach the previously prepared bare wire cable ends into the banana plugs and secure the connections. Refer to figure F.
-
Rotate the top of the Output Terminal Post clockwise until it is finger-tight. Refer to figure G. Then using the McIntosh Wrench, rotate the top of the Output Terminal one-quarter of a turn (90°). Do not over-tighten. Refer to figure E.
-
Referring to figure H, connect the Loudspeaker hookup cables with banana plugs into the hole at the top of the MC3500 Negative (-) and Positive (+) Output Terminals. The Positive Terminals are identified as 2Ω (ohms), 4Ω (ohms) or 8Ω(ohms) connections to match the impedance of the Loudspeaker, being careful to observe the correct polarities.
If the Loudspeaker’s impedance is in-between the available connections, use the nearest lower-impedance connection. WAR NING: Loudspeaker Terminals are hazardous live and present a risk of electric shock. For additional instruction on making Loudspeaker Connections, contact your McIntosh Dealer or McIntosh Technical Support. -
Connect the MC3500 Power Cord to an active AC outlet.
Spade Lug or Wire Connections: -
Connect the Loudspeaker hookup cables to the MC3500 Negative Output Terminal (-) and Positive Output (+) Terminal identified as 2Ω (ohms), 4Ω (ohms), or 8Ω (ohms) connection to match the impedance of the Loudspeaker, being careful to observe the correct polarities. Insert the spade lug connector or prepared section of the
cable end into the terminal side access hole, and tighten the terminal cap until the cable is firmly clamped into the terminals so the lugs or wire cannot slip out. Do not over-tighten. Refer to figures 4, 5, and figure E.
If
the Loudspeaker’s impedance is in-between the available connections, use the
nearest lower-impedance connection.
WAR NING: Loudspeaker terminals are hazardous live and present a risk of electric shock. For additional instruction on making a Loudspeaker For connections contact your McIntosh Dealer or McIntosh Technical Support. -
For a Stereo system, repeat steps 2-8 for the other channel.
-
Connect the MC3500 Power Cord to an active AC outlet.
Navigating the Front Panel
- Power Output Meter: Displays power output level in Watts and Decibels.
- Meter Control Knob: Select between the different Output Meter functions (see next page).
- Warmup LED: Illuminates to indicate when the Warmup state is active (see next page).
- Standby LED: Illuminates whenever the MC3500 is connected to a live AC outlet. Flashes whenever Sentry Monitor has activated (see next page).
- Power Guard LED: Illuminates to indicate when the power Guard is active.
- Power Knob: Turn MC3500 On/Off, or set to REMOTE position to have it be turned On/Off automatically by a Preamplifier (see next page).
How to Operate
Power Control
The POWER CONTROL is located on the Front Panel of the MC3500. Set the Control
to the REMOTE Position. Refer to figure 10. The MC3500 Power Amplifier will
turn ON or OFF as the Preamplifier it is connected to (via the Power Control
Connection) turns On or Off. For manual operation, place the POWER CONTROL in
the ON Position as desired. The LED indicator located on the Front Panel is
illuminated when the MC3500 is connected to an active AC Outlet.
When the MC3500 is first switched n, there is a Warmup period of time during
which no sound will be heard and the WARMUP LED will illuminate. During this
period, the Power Output Meter needle will gradually rise to show the warmup
percentage. After the needle reaches 100%, the MC3500 will begin playing
sound, the WARMUP LED will switch off, and the needle will return to
displaying the appropriate- POWER REMOTE OFF ON Figure 10 ate Output based on
the Meter Control Knob position (see below).
Meter Control
The Meter Control Knob changes how the Power Output Meter behaves. If the Knob
is set to WATTS, the Meter will continuously respond to and display the
current Output of the MC3500. Refer to figure 11. If the Knob is set to HOLD,
the Meter will display the highest peak Output in a series of peaks, until a
greater peak is read. If no greater peak is read, the Meter will begin to
lower at a rate of approximately 6dB per minute. Fig ure 11
While the Knob is set to either WATTS or HOLD, the Power Output Meter light
will be powered On/Off by a Preamplifier or A/V Control Center connected by a
Power Control Cable if that unit has Power Control capabilities. If the Knob
is set to LIGHTS OFF, the Power Output Meter light will be permanently off,
and the Meter will respond as if the Knob was set to WATTS.
Input Switch
The Input Mode Switch, which is located on the Rear Panel of the MC3500,
allows the selection of either the Balanced or Unbalanced Input. Refer to
figure 12.
Auto Off Switch
The MC3500 incorporates Power Save Circuitry to automatically place the MC3500
into the power saving Standby Mode approximately 30 minutes after there has
been an absence of an audio input signal. When there is a Power Control Connection between the MC3500 and a Preamplifier with Power Save Circuitry, the AUTO OFF Switch is bypassed (located on the Rear Panel of the MC3500). Refer to figure
- In the event there is no Power Control Connection and the Power Save
Circuitry is activating inappropriately relative to your specific use of the
MC3500, place the AUTO-OFF Switch in the DISABLED position. If the Power Save
Circuitry has switched Power to the
MC3500 OFF, place the POWER in the OFF Position and then in the ON position to reset the circuitry.
Sentry Monitor Reset
Sentry Monitor provides protection for the MC3500 by monitoring Output. In the event of a large impedance mismatch, a short circuit at the Output Terminals, or Tube failure, Sentry Monitor will activate to prevent potentially destructive levels of current from flowing. When Sentry Monitor is activated, the MC3500 will power off, and the Standby LED will flash. To reset the Sentry Monitor Protection Circuitry, turn the Power Control Knob to OFF. (See “Power Control” on the previous page). Then, turn the Power Control Knob to ON. If Sentry Monitor continues to engage, the problem must be fixed before continuing. Check that wires connected to the Output Terminals and the Loudspeaker Terminals are not shorted. If those connections are fine, and the Impedance of the Loudspeakers is close to the value of the connected Output terminals, the issue may be a defective tube. When the MC3500 doesn’t return to Normal Operation after the Power Switch has been switched back ON, then place the Power Switch in the OFF position and disconnect the AC Power Cord from the MC3500. Then contact your McIntosh Dealer for the repair of the Power Amplifier.
Amplifier Specifications
Power Output
350 watts into 2 ohm load
350 watts into 4 ohm load
350 watts into 8 ohm load
Rated Power Band
20Hz to 20,000Hz
Dynamic Headroom
2.4dB
Wide Band Damping Factor
Greater than 25
Frequency Response
+0, -0.5dB from 20Hz to 20,000Hz
+0, -3.0dB from 10Hz to 70,000Hz
Total Harmonic Distortion
0.3% maximum harmonic distortion at any power level from 250 milliwatts to
rated power, 20Hz to 20,000Hz
Intermodulation Distortion
0.3% maximum, if the instantaneous peak power output does not exceed twice the
rated power output for any combination of frequencies from 20Hz to 20,000Hz
Signal To Noise Ratio (A-Weighted)
120dB below rated output
Input Sensitivity (for rated output)
3.8 Volts Balanced
1.9 Volts Unbalanced
VoltageGain
29dB, 8 Ohms
26dB, 4 Ohms
23dB, 2 Ohms
Input Impedance
22,000 ohms Balanced
22,000 ohms Unbalanced
General Specifications
Power Control Input
5-15VDC, less than 1mA
Power Control Output
12VDC, 25mA (Delayed 0.2 seconds from power on)
Power Requirements
100 Volts ~ 50/60Hz at 7.2 Amps
110 Volts ~ 50/60Hz at 6.0 Amps
120 Volts ~ 50/60Hz at 6.0 Amps
127 Volts ~ 50/60Hz at 6.0 Amps
220 Volts ~ 50/60Hz at 3.3 Amps
230 Volts ~ 50/60Hz at 3.3 Amps
240 Volts ~ 50/60Hz at 3.3 Amps
Standby, less than 0.5 watt
Refer to the rear panel of the MC3500 for the correct voltage.
Overall Dimensions
Depth is 21-5/8 inches (54.9cm)
Width is 18 inches (45.7cm)
Height is 11-13/16 inches (30cm)
Weight
121 pounds (54.9kg) net
147 pounds (66.7kg) in the shipping carton
Shipping Carton Dimensions
Depth is 31 inches (78.7cm)
Width is 28 inches (71.1cm)
Height is 17-1/4 inches (43.8cm)
Packing Instructions
In the event it is necessary to repack the equipment for shipment, the
equipment must be packed exactly as shown below. It is very important that the
four feet are attached to the bottom of the equipment. This will ensure the
proper equipment location on the bottom foam pad. Failure to do this will
result in shipping damage.
To protect the tubes during shipment, the Foam Insert removed from the MC3500
needs to be re-inserted.
Follow the unpacking instructions on pages 4-5 in reverse order.
Use the original shipping carton and interior parts only if they are all in
good serviceable condition.
If a shipping carton or any of the interior part(s) are needed, please call or
write Customer Service
Department of McIntosh Laboratory, refer to page 2.
Please see the Part List for the correct part numbers.
| Quantity1 | Part Number | Description |
|---|---|---|
| 1 | 34105 | Shipping Carton Top |
| 1 | 34104 | Shipping Carton Bottom |
| 1 | 34680 | Tube Foam Insert |
| 2 | 34679 | Pad Top/Bottom |
| 3 | 34678 | Foam Ring |
| 1 | 241109 | Warning Sheet |
| 1 | 33739 | Poly Bag |
McIntosh Laboratory, Inc.
2 Chambers Street
Binghamton, NY 13903
www.mcintoshlabs.com
The continuous improvement of its products is the
the policy of McIntosh Laboratory Incorporated who
reserve the right to improve design without notice.
Printed in the U.S.A.
McIntosh Part No. 24113800
Documents / Resources
|
McIntosh MC3500 Mono Tube
Amplifier
[pdf] Owner's Manual
MC3500 Mono Tube Amplifier, MC3500, Mono Tube Amplifier, Amplifier
---|---
References
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