Premium Tested and Precision Matched Preamp and Output tubes for the Discriminating Musician and Audiophile

A WORD ABOUT OUR PRECISION MATCHED TUBE SETS:

SRS offers premium, fully tested preamp, rectifier and output tube sets to the discriminating musician and audiophile, for the ultimate in richness and tone. Our carefully tested and grouped sets will definitely improve the sound and tone coming from your tube amplifier. Our premium precision matched tubes are equally at home in vintage guitar amps, modern high-gain amp circuits, as well as state of the art high-end, high fidelity stereo tube amplifiers- you won't find a better set of matched tubes anywhere, period.

SRS Premium matched output tubes are tested a minimum of 8 ways before being grouped into pairs and quads:

1. Visual- a close visual inspection of the internal components, glass, flashing, and pins. Tubes which fail this initial visual inspection are discarded immediately.

2. Shorts- our tubes are tested on two different machines for shorts: a preliminary test for apparent dead shorts from pin to pin, and then a dynamic short-circuit test under full power. Tubes which fail either test are discarded immediately.

3. Gas- all tubes are fully tested for a good, tight vacuum, on two separate machines during the pre-matching stages of our process. A "gassy" tube will draw excessive current and/or fail prematurely. All tubes which fail either test are discarded immediately.

4. Shock test- every tube is subjected to minor shock/vibration while under full operating conditions, to weed out potential failing tubes due to structural integrity- while fully warm and under full plate voltage, each tube is subjected to a mild bump and vibrations similar to what could occur in "real world" conditions, to ensure no loose connections or intermittent shorts- any tube which fails this test is immediately discarded, *before* it happens in your amplifier. This insures that not only will your tubes sound great, but will adhere to a high standard of ruggedness as well!

5. Plate current- this test is performed under normal operating circumstances, using the proper high plate voltage that exists in most tube amplifiers- a lot of tube testers do not put enough voltage on the plates during testing, which can affect test results dramatically. Our state of the art equipment tests our tubes at normal(475+ VDC) working voltages, giving much more accurate "real world" performance results.

6. Dynamic Mutual Conductance- Most folks who "match" tubes only measure the cathode current draw, grouping tubes which draw similar current into sets. SRS Premium matched tubes go much further, testing the conductance of the tubes as well, ensuring that all tubes in a group will function in a like fashion, with regards to how much current they draw from the circuit, and what is coming out the other side.

7. Noise/Microphonics- All of our tubes must pass a strict audible noise and microphonics test- tubes which ring, buzz, or hum excessively are immediately discarded.

8. Real-world audio tone test- as the last step in our testing process, SRS Premium matched output tubes are tested in actual amplifiers for proper tone and harmonics- occasionally, tubes can pass *all* of the above steps but still not have that special rich tube sound- each and every set is auditioned for proper DYNAMICS, HARMONICS, AND TONE.

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