McIntosh MX110 Tube Tuner Preamp - Modafferi Upgraded & SkyFi Restored

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One of the cleanest MX110's we've seen to date. Stunning to look at and great sounding too.

And we have the paperwork to prove this MX110 was serviced by McIntosh legend Richard Modafferi.

This example also has a Z series serial number indicating it was the improve later production model. 

Restored in-house and working as it should throughout, plus check out the included custom clear-top wood cabinet!

The chrome is as good as it gets with only the slightest signs of pitting. 

This SkyFi restored MX110 will ship in a modern factory fresh double McIntosh box to ensure safe travels worldwide. The custom cabinet will ship in a separate box.

And here's an MX110 walkthrough from our YouTube channel from a previous MX110 listing:

SkyFi Restoration Notes:
This example was previously serviced by Richard Modafferi himself at Audio Classics in 2004.

The service receipts show that modifications were made to the internals of some of the IF transformer cans for better reliability. The transistor responsible for the stereo beacon indicator was also upgraded at the same time.

When we received this MX110 it had developed some new power supply issues related to a couple of the multi-section capacitor cans. We decided to put this unit through our in-house restoration process which included a full power supply rebuild.

All multi-section capacitors  were replaced with custom made equivalents. The Main power supply's selenium rectifiers were replaced with a single silicon bridge rectifier with proper compensation to match the original schematic voltages.

All remaining electrolytic capacitors were replaced, and the tuner received a touch up alignment to the dial tracking and stereo separation. We also cleaned the glass and installed new lamps.

This example was thoroughly tested on our bench and listening room tests and performs very well on phono, line level, and tuner functions.

The only issue that we observed was a slight frequency response discrepancy between channels which can be resolved by sightly rotating one of the treble controls. These dual concentric tone controls develop drift over time which results in minor channel discrepancies. During our testing we had all controls set to flat and did not see any noticeable difference between channels on our bench or on listening review.

Cosmetic Notes:
The chrome chassis shows a bit of pitting and the glass has minor paint blemishes. Specifically in the upper left corner (See Images).

Please see our photos or the manual linked below for full specifications. 

McIntosh MX110 - Owners Manual

Click below to add our recommended matching cables from Kimber Kable, all brand new as SkyFi is an official Kimber dealer.

Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

Kimber Kable - Phono Interconnects - Better

Kimber Kable - Flagship Tonearm Interconnects - Best

The SkyFi Testing Process for Preamplifiers:
We start with a visual inspection of all internal components to make sure that there are no signs of heat stress or damage. Capacitors are checked for telltale signs of predictive failure including bulging, shrunken wrappers, or physical leakage. We also inspect the PCBs for discoloration from resistors or transistors that may have been running hot. On vintage units we often spot check select capacitors for value and ESR.

When we first power on a preamplifier we connect its RCA output to a Sencore PA81 Power Analyzer which simulates real world loading conditions and gives us an oscilloscope interface. The first order of business is checking that the volume control works smoothly throughout its entire range with acceptable channel balance. This is accomplished by feeding a 1KHz sine wave into one of the preamp’s line level inputs while monitoring the preamp’s output on an oscilloscope. We then switch to a 1KHz square wave to test the tone controls, loudness function, and filters where applicable. During this step we are watching for equal alteration of the test signal by both channels. This also helps us identify dirty controls that will need treatment. Once the basic line stage functions are verified, we test each input individually. This is especially important for devices that use relays to select their sources. If the preamp is equipped with a phono stage we test that as well. We use an inverse RIAA filter which allows us to feed a reference test signal into the phono input with the proper RIAA equalization and level. A square wave or sine sweep is used to verify that the device’s phono stage is faithfully reproducing the RIAA curve. If the preamp under test has balanced inputs and/or outputs these are tested as well.

We finish up our bench testing with a listening test with our bench amplifier and reference speakers. During this test we check for hum or hiss that may not have shown up in earlier testing. We also check that all of the tone controls and filters perform as expected. If the preamplifier has remote control functions these are also tested. Preamps with tube circuits or complicated power supply topologies are connected at our long term test rig for extended stress testing under real world conditions.

The SkyFi Testing Process for Tuners:
We start with a visual inspection of all internal components to make sure that there are no signs of heat stress or damage. Capacitors are checked for telltale signs of predictive failure including bulging, shrunken wrappers, or physical leakage. We also inspect the PCBs for discoloration from resistors or transistors that may have been running hot. On vintage units we often spot check select capacitors for value and ESR. Vintage analog tuners also have moving parts related to the tuning gang and dial string. These parts are inspected for smooth operation.

If the unit passes visual inspection it is bench tested for a handful of key performance parameters using a Sencore SG80 AM/FM Stereo Analyzer. The SG80 allows us to “simulate” an ideal radio station using precision test signals instead of music. This device, in conjunction with an oscilloscope allows us to properly evaluate the following parameters:

1. AM Reception (Where Applicable)
2. FM Mono Reception & Tuning Meter Function
3. FM MPX Reception (Stereo)
4. Dial Tracking - How accurately the tuner dial or display indicates the actual frequency of the broadcast being received.
5. Stereo Separation - A properly working stereo tuner will have minimal crosstalk between the left and right channel.
6. Sensitivity & Signal Strength Meter Function - By lowering the output of the SG80 we can simulate weak stations and determine how well the tuner will be able to pull in weak distant stations. This adjustment also helps us verify signal strength meter function.

If the tuner has acceptable performance related to the parameters above we connect the unit for listening tests with a simple dipole antenna. We listen for audio reproduction quality of local stations and evaluate how many stations the tuner can receive while we sweep through the dial. We are looking to verify that the tuner can decode stereo on strong local broadcasts and pick up a wide variety of local stations at the bottom, middle, and top of the frequency band. At this point we also test convenience features such as muting, filters, built in oscilloscope function, etc.

We finish up with an extended listening test on our long term test rig. We tune in a strong local station and monitor for drift over a 2-3 hour period.