128-165-PAE

Click here to order: Assembled, PCB Only

Click here to download the installation guide: Assembled, PCB Only

This is a new-production input preamp board for the McIntosh MC2100, MC2105, and MC2300 power amplifiers. This board follows the original component layout closely, and no changes were made to the original circuit design. Available assembled and tested, or as an unpopulated PCB.

The new PCB is double-sided and uses 2-ounce copper, plated through-holes, an immersion gold finish, and matte black soldermask. Silkscreen reference designators and symbols are provided on both sides. Robust wiring turrets replace the original hollow posts that cables solder to. All component footprints are sized to fit the original parts. In addition, all axial electrolytic capacitors have footprints for radial parts of various sizes, both input film caps support two different lead spacings, and both electrolytic output caps can be substituted with film caps of the appropriate physical size. A capacitor sizing guide is included with unpopulated kits.

Assembled boards are built using high quality components, including Vishay MRS25 series low noise metal film resistors (1% tolerance, 600 mW, 50 ppm TCR), Nichicon electrolytic capacitors (UPM series for supply filters, UKZ for audio stages), WIMA film capacitors, and new transistors. All assembled boards are burn-in tested for 24 hours and run through an Audio Precision analyzer to confirm that they meet the performance specifications listed below.

Parts Included (Assembled Board)

• Assembled and tested MC2100/2105/2300 input preamp board
• Anti-static bag for storing your original input board
• Two 22 kOhm resistors for MC2300’s below S/N 4Y426
• Installation guide with redrawn schematic, board layout, and parts list

Parts Included (Unpopulated PCB)

• Unpopulated MC2100/2105/2300 input preamp PCB
• 16 wiring turrets (one extra)
• Anti-static bag for storing your original input board
• Resistor lead forming tool
• Installation guide with redrawn schematic, board layout, and parts list

Typical Performance

Typical performance of both channels (Audio Precision analyzer, 2 Vrms output from DUT):

• Gain: 20.83 dB @ 1 kHz
• Frequency response: +0.01 dB, -0.25 dB from 20 Hz to 20 KHz
• Signal to noise ratio: -97.1 dB below 2 V output (20 Hz – 22 KHz analyzer fltr, unwtd)
• THD+N: Less than 0.007% from 20 Hz – 20 KHz (no analyzer fltr, unwtd)
• IMD: Less than 0.005% (DIN 250 Hz/8 KHz 4:1)

Note that these specifications apply to the preamp board by itself and do not reflect the overall performance of your McIntosh amplifier. We have tested an original MC2100 input board in the same manner and found that this new board slightly exceeds the performance of the original.

We recommend testing your unit first to ensure it is working properly. If you are repairing your unit, please make sure your symptoms are originating from the preamp board before you replace it. Replacing this board will not resolve problems present in the rest of the unit, such as the power supply or amplifier sections. If you have not replaced the original multi-section can capacitor in your unit’s power supply, we recommend doing so; we offer a replacement capacitor kit with a custom designed PCB for this task.

Please do not attempt to install these boards if you are not thoroughly familiar with safely diagnosing, repairing, and testing amplifiers at the component level with test equipment (signal generator, oscilloscope, load, etc.) and a current-limited power supply.