Day Sequerra 25th Anniversary FM Reference Tuner - The Ultimate Tuner

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If you follow our store you've probably seen several of the vintage Sequerra tuners we've offered over the past few years.

It has always been *by far* our most revered tuner.

But we were left wondering how the vintage Sequerra would stack up against the latest version. So we sent one out to be officially upgraded by Day Sequerra to the latest and greatest spec!

While this cost us a significant amount of time and $$$, it sure was worth the effort. Not only did the tuner come back sporting a brand new display, but it performs better than it ever did. 

Plus there's a one year limited warranty on each FMR25 upgraded tuner, even covering the parts that are 25-years old!

This unit now looks brand new and will arrive at your door in the original packing.

More from Day Sequerra follows below.

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

Summit Series Silver Streak Analog Interconnects (PAIR) - BALANCED XLR Connectors

Summit Series Silver Streak Analog Interconnects (PAIR) - RCA Ultraplate or WBT Connectors

Kimber Kable - Base Series PK14 Power Cord - Brand New

From Stereophile:

DaySequerra is celebrating its 25th anniversary of the launch of its famed FM Reference by announcing an FMR 25 upgrade program for your tuner, available factory-direct for $3800.

The FMR 25 upgrade is designed to breath new life into every DaySequerra FM Reference by addressing head-on the two major challenges facing the 25 year-old high performance analog design:

Limited life expectancy of its cathode-ray tube (CRT) display used for tuning and audio displays

Reduced signal-to-noise performance caused by HD RadioTM OFDM sideband interference, commonly called HD Radio “self-noise”.

Other electronic components typically effected by old age, such as incandescent bulbs are also replaced with more modern solutions to extend the FM Reference’s useful life.

TFT to the Rescue. To replace the decades-old CRT display, DaySequerra engineers developed a synthesized VHDL file to configure a Xilinx Spartan 6TM Field Programmable Gate Array (FPGA). The analog IF and audio signals are digitized using a 64X oversampling TI Burr-Brown 24-bit, 96 KHz A-D converter; the FPGA then processes each respectively to provide the Tuning and Audio Vector displays. The user-selected display is output to high contrast 480 by 272 pixel ruggedized TFT display with a fast 20 mS response time.

The resultant front panel display has more contrast than the original CRT and its blue trace compliments the DaySequerra timeless industrial design.

Another benefit to eliminating the CRT is a substantial reduction in internal heat and electrical noise on the ground plane caused by the original high-voltage CRT drive circuitry.

HD Radio – Analog Radio Interference. HD Radio was approved by the Federal Communications Commission in October 2002 as the only system for digital AM and FM broadcasting in the United States. HD Radio In-Band On-Channel (IBOC) technology is developed and licensed by iBiquity Digital Corporation, and HD Radio broadcasts are available subscription-free but require specially designed HD Radio enabled receivers.

One negative side-effect of HD Radio IBOC broadcasting is an increase in the analog FM stereo noise floor caused by IBOC Orthogonal Frequency Division Multiplex (OFDM) sidebands; this is known in the industry as HD Radio “self-noise.” HD Radio self-noise negatively affects the performance of almost all analog radios in the U.S.

Stop. Here’s a message from our Legal Department.

1]. The term “HD” in HD Radio does not stand for “high definition” rather it relates to “hybrid digital” technology used in HD Radio.

2]. DaySequerra is the leading provider of AM-FM-HD modulation monitors and confidence monitors to radio broadcasters in the U.S.

3]. DaySequerra’s founder, David Day, speaking at a recent National Association of Broadcasters convention said “Taken as a whole, HD Radio delivers incredible dynamic range with a vanishingly-low noise floor. The HD Radio lossy-codec is quite good; and while not as transparent as the best closed-circuit analog FM broadcasts, its real-world performance and feature-rich user experience outweighs its shortcomings, and moves broadcast radio into the internet age.”

There are now over 3,000 FM stations broadcasting HD Radio in the U.S, meaning there are HD Radio stations on-the-air in every major U.S. market.

HD Radio Self-noise. As stated earlier, HD Radio self-noise and increased IBOC power provide for a lively dialog in the industry. Simply put, HD Radio self-noise substantially increases the FM analog stereo noise floor; this is caused primarily by the linear sum and intermodulation of the FM analog FM L+R (sum) L-R (difference) signals and IBOC OFDM sidebands. In most high-quality FM receivers, this means more than a 40 dB increase in stereo noise floor.

In the DaySequerra FM Reference in Wide IF Bandwidth mode this means a substantially decreased SNR: from -75 dB to -25 dB, meaning continuous hiss and white noise on every HD Radio FM station and on most analog FM stations adjacent to any FM HD Radio station.

Back to Basics. Luckily for DaySequerra, the solution to HD Radio self-noise in the 25-year old FM Reference design was fairly straightforward and has almost no side effects: a post-FM demodulation filter designed to remove noise energy starting at 53 KHz and above.

As illustrated below, if the post demodulation filter removes most noise energy above 99 KHz, there will not be any noise energy to translate into the audio band by the FM Reference’s stereo decoder. The challenge here however was to preserve the L-R response so that stereo separation was not negatively effected while eliminating the noise above 99 KHz. DaySequerra’s engineers employed a 7th order elliptical filter to maximize the attenuation of noise outside the pass band while minimizing group delay variation.

Recently upgraded FM Reference units have measured SNR of better than -78 dB (3 dB improvement over 25 years ago) and stereo separation of better than 50 dB – equal to pre-upgrade performance.

Other Improvements. The FM Reference 25 Upgrade includes a few other improvements as well: new hand-matched JFETs are installed in the IF filter amplifiers and in the input buffer for the Class-A biased audio outputs. And all incandescent bulbs are replaced with LEDs.

There is a one year limited warranty on each FMR25 upgraded tuners, even covering the parts that are 25-years old.

New shipping materials are available for safe shipment of units to and from the factory.

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.