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Wavelength Audio - Cardinal 300B SET (Single-Ended Triode) Monoblock Tube Amplifiers

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Pickup currently unavailable at SkyFi 479

Wavelength Audio - Cardinal 300B Set (Single-Ended Triode) Monoblock Tube Amplifiers Amplifier

Wavelength Audio - Cardinal 300B SET (Single-Ended Triode) Monoblock Tube Amplifiers

SkyFi 479

Pickup currently unavailable

479 South Broad Street
Glen Rock NJ 07452
United States


Great sounding low power amplifiers from Wavelength Audio. 

Both are in super clean condition, and both are fully tested and ready to rock and roll your high efficiency speakers.

Includes Electro Harmonix 300B type tubes installed as shown in our photos.

Both also include their original boxes.

From Sam Tellig and the January 1996 edition of Stereophile:

"The standard-edition Wavelength Audio Cardinal is priced at a mere $5250/pair. Each monoblock uses a 5AR4 to rectify the high voltage for the plate supply, a 6SL7 in the gain/driver, and a single 300B output tube. Brown-bottomed Golden Dragon 300Bs are standard. Various tube choices are available from the manufacturer, including original Mullard 5AR4s. The power is rated at 7+ watts per channel (Wpc).

Let's see...$5250/pair divided by two, divided by 7. That's $350 per watt per channel. We're talking bargain here, compared to Jadis."

Specifications - Single-ended class-A triode monoblock amplifier

Originally Equipped Tube complement, each amplifier):
Mullard 5AR4/GZ34 rectifier
Sylvania 5691 (black base) input/driver
300B VAIC VV30B Type 1 output

Power output:
8-9W depending on driver tube

Overall voltage gain:

Frequency response:
18Hz-15kHz, -1dB
10Hz-28kHz, -3dB

Dimensions, each:
9" H by 12" W by 14" D

38 lbs each

Original MSRP in 1995:

Wavelength Audio
Cincinnati, OH, USA

The SkyFi Testing Process for Tube Amplifiers:

We start with a visual inspection of all internal components to make sure there are no signs of stress or aging. Capacitors are checked for telltale sings of bulging or leaking, resistors are checked for signs of overheating or cracking, and tubes are inspected for signs of stress overheating or cracking.

We then power up the unit carefully and run a simple 1k sine wave while monitoring the output on an oscilloscope for signs of distortion or noise. Finally we run the amplifier to its full rated power into the appropriate resistive load provided by our Sencore amplifier tester. If there is an issue, it will usually be noticeable at this point. If it all looks clean we will often test for THD (Total Harmonic Distortion) measured by our Keithley distortion meter, and compare it against the original manufacturers specifications. The amplifier the remains powered on to "burn in" on our test bench for a few hours to make sure there are no heat related issues. If there are balanced inputs available they will also be tested.

We also test all tubes for output gain and leakage on our calibrated B&K 747 tester against the original manufacturers specifications. If needed, the tubes will be replaced from our vast NOS (New Old Stock) vintage or modern inventory.

Final testing involves pushing actual music thorough the amplifier. We've learned over time that some issues are only noticeable to a trained ear while listening to familiar source material. Our test bench has reference vintage KEF speakers that we're very familiar with which quickly reveal any discrepancies. Some amplifiers will then move into our listening room where they are tested with our in-house reference speakers of choice.

Please click here for detailed specifics regarding our specialized packing process that separates us from the rest.



Original Box





Not Applicable


Yes - Power

Physical Condition


Working Condition


SKU: 101995