PRODUCTS AND SERVICES
- VINTAGE TUBE AMPLIFIER REPAIR AND RESTORATION: MARANTZ,
McINTOSH, SCOTT, FISHER, HARMAN-KARDON AND OTHERS
- SOLID STATE AMPLIFIER REPAIR, RESTORATION AND MODIFICATION
- POWER AMPLIFIER DESIGN AND PROTOTYPING
-
NOW OFFERING NEW MAKE TUBE AMPLIFIERS!
Contact North Reading Engineering at: audio@northreadingeng.com
WELCOME TO NORTH READING ENGINEERING
North Reading Engineering is all about audio amplifier engineering
offering new make, USA manufactured tube amplifiers, restoration
services for vintage tube classics and replacement PC board assemblies
for first generation McIntosh solid-state amps.
MODEL 219, 2-CHANNEL, PUSH-PULL
AMPLIFIER
Super heavy duty chassis, extreme build quality, very low distortion,
broad bandwidth and high reliability make the MODEL 219 a basic tube
amplifier you must have! Click on either photo below for
additional information on this beautiful amplifier.
For amplifier builders, the Sallen-Key module provides two, 4th order, band-pass small signals to amplifier inputs. Designed to accept a wide range of capacitor values to implement band-pass filtering for woofer, midrange and tweeter applications. On-board +/-15VDC regulated on-board supply, Sallen-Key filter topology USA made, through-hole PC boards with clear, bright silk screened component IDs are also available to allow amp builders to evaluate and modify the design to suit specific filter requirements. For more information including performance data and ways to use this module is found HERE.
BALANCED 2-CHANNEL, BUFFER / 3-WAY ACTIVE SPLITTER FRONT END MODULE
EMI/RFI hardened amplifier front-end, XLR/TRS combination inputs, +/-15VDC
regulated on-board supply, ultra-low distortion, super quiet buffer/splitter accepts
inputs from any small signal source and splits them into three independent
signals, each capable of driving an amplifier
in a bi- or tri-amplified loudspeaker system. Op-amp sockets
enable users to evaluate different packages or replace a blown device.
High quality, USA made, through-hole PC
boards with clear, bright silk screened component IDs are also available to allow amp builders to evaluate and
modify the design to suit specific buffering requirements. For more
information including performance data and ways to use this module is found
HERE
(webpage) and
HERE
(video).
VINTAGE McINTOSH AMPLIFIER SERVICING
North Reading Engineering has the experience,
tools and test instrumentation to properly assess the condition of your vintage, first gen solid state amplifier
and make it a whole lot better. More information on amp servicing can be found
HERE.
A complete
rework of an MC2100 amplifier is shown on the forum website
HERE.
MC2105/2100, 2505/250 and 2300 PREAMP BOARD UPGRADE /
REPLACEMENT
First generation McIntosh solid
state amps can be
upgraded to make better sound. This isn't a "re-cap" or "update"
of the original design. It's a re-engineered preamplifier section, designed as
a direct swap for the 043-795 and 044-331 preamplifier boards (lower
left). The
new preamplifier board (lower right) provides a significant, measureable performance upgrade to these vintage
classics. More information on the preamplifier section can be found
HERE.
A beautifully done customer MC2105 install
HERE.
(Note: Bare PC boards are no longer sold for
customer assembly, only fully assembled and tested boards are
available.)
MA6100 INTEGRATED AMPLIFIER
POWER SUPPLY BOARD REPLACEMENT
The MA6100
restoration package replaces the thermally distressed, old school,
turret board supply (lower left) with a completely new, drop-in, PC
board fabricated from a high current capacity, dual-trace, USA
manufactured board (R1.1). The board and component selection have been
engineered to manage the excessive heat generated by regular amplifier
use. The supply section has demonstrated superior heat management and
excellent reliability. The assembled and tested power supply board is also
available for purchase for installation by the customer. A high resolution image of the board top shown
HERE and bottom
HERE.
The development process of
the power supply board showing the prototype R1.0 and final R1.1 version
with installations shown
HERE. (Note: Bare PC boards are not sold for customer assembly, only fully
assembled and tested boards are available.)
MA6100
RESTORATION
Factory polyester replaced with WIMA MKP polypropylene caps in preamp, phase inverter and voltage regulator boards (photo lower right).
Large filter caps replaced, small-signal by-pass caps replaced with low DC leakage, solid Tantalum electrolytics.
Power output driver
complimentary pair and voltage amplifier stage removed, heat sinks and mica insulators cleaned, thermal compound applied
and reassembled. All output stage power transistors
replaced. Amplifier is dismantled and chassis cleaned and polished (lower left).
Previous repairs are identified, reworked as required. Blown transistors can be matched and installed. Chassis fasteners replaced
with stainless steel, new plastic chassis feet attached, panel lamps replaced with LEDs, glass faceplates, NLA Amphenol card edge connectors and
multi-can caps can be sourced and installed (pending inventory).
Reworking MA6100 PC boards is shown
HERE.
MC250/2505 RESTORATIONS
Preamplifier, Power Supply and Output
Stages
Factory preamplifier replaced with the R2.3 preamplifier assembly.
Power supply and output power board capacitors replaced, output
transistors replaced, potentiometers, RCA jacks, rockers switches
replaced, chassis stainless steel cleaned, polished with new stainless
steel chassis hardware. Chassis bottom, prepped and painted (lower right).
A reworked MC250 is shown
HERE.
VINTAGE VACUUM TUBE AMPLIFIER RESTORATION
MARANTZ, McINTOSH, SCOTT, FISHER, HARMAN-KARDON AND OTHERS
Power supply rebuilds, power supply transformers replaced with new
replacement units, power supply/bias supply recaps, board
replacements, RCA jacks, barrier strips, potentiometers, meters replaced, chassis top sections replaced with
new make reproductions
(McIntosh), chassis bottom covers refinished. Powder coating, metal refinishing, sheet metal fabrication,
CNC machining services
available.
McIntosh vacuum tube restorations!
MODELING THE KLIPSCHORN BASS HORN (Part I) - The Beranek Model, LTSPICE and a slew of measurements.
MODELING THE KLIPSCHORN BASS HORN (Part II) - Extending the model to simulate factory filter responses.
PHOTOGALLERY OF A KLIPSCHORN REPLICA BUILD - Building a Klipschorn is not for the faint of heart!
A KLIPSCHORN NETWORK FOR BUILDERS - A measured design you can build yourself.
UNDERSTANDING IMPEDANCE - Resistance, Reactance, Nyquist and Excel all in one place.
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No part of the above may be copied and published, in part or in total, without permission.
Contact: audio@northreadingeng.com
Phone: (978).795.7172
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