The rare and beautiful Transcendent Sound SE-OTL amplifier. This is without a doubt one of the legendary Bruce Rozenblit’s best designs. Dead quiet, powerful and tight bass, silky smooth highs. The tubes are inexpensive and long-lasting. This is a true class A amplifier with 1.5 watts of power, so be sure your speakers are efficient. I have used it successfully with Klipsch Cornwall II (101db), Altec Lansing 846b Valencia (98db) and for near-field operation with my PC, Wharfedale Opus 2 M2 (88db) speakers.
I purchased this unit in November, 2012 from the original owner who built it from a kit. The construction was strictly per the book with no modifcations.
The amplifier was part of my office system, kept in a smoke-free environment. I used it with the Transcendent Sound Grounded Grid preamp and Klipsch Cornwall II speakers. It is in excellent working order and I am only selling it because I have recently retired.
From the manufacturer’s site:
OTL has proven to be the most musical and realistic method for push-pull amplification. We have applied all of the benefits of OTL to Class A Single-Ended amplification. The result is a higher benchmark of performance that has been unattainable until now. Experience your music for the first time.
High-efficiency speakers are known for extreme detail and dynamics. They can resolve the most minute characteristics and subtleness of the musical signal. For maximum performance, they should be driven with an amplifier that can render their qualities to the fullest extant possible. This is such an amplifier.
Just as with our push-pull amplifiers, eliminating the output transformer removes all of the sonic limitations and colorations of transformer coupling-allowing the music to achieve a level of realism not possible with conventional techniques. The benefits are many:
1) Speed: This amp is fast: Full power bandwidth is flat to well over 100 kHz. The high speed preserves all transient and dynamic information in the signal. Now, your speaker can finally work up to its full potential and really breathe life into the music. While being fast, the amp is velvety smooth and musical. There is absolutely no harshness or edge to the music. This is a single-ended amplifier and it sounds like a single-ended amplifier.
2) Great Bass: Because there is no output transformer, bass response is not attenuated in any way. The amp is flat ( -0.25 dB) to 10 Hz! Bass tones are full and lifelike. The amplifier is perfect for driving large full range horns with no loss of bass energy. Output impedance is a very low 1 ohm. This is much lower than most conventional single-ended amplifiers and provides excellent woofer control giving very clean and sharp bass transients. Percussive sounds are crisp and true.
3) Ultra Low noise: When driving high efficiency speakers, noise is a terrible problem. The speakers let everything through. Broadband noise measures less than 200 microvolts unweighted. This is extremely low and quite possibly the quietest tube amplifier on the market regardless of price. (Unweighted noise measurements are more conservative and always higher than commonly used "A" weighted noise figures.) No more irritating buzzes and hums during quiet passages. Many other single-ended amplifiers have noise levels well over 1000 microvolts.
4) Low cost: High quality output transformers for single-ended amps are extremely expensive as are the tubes that are required to drive them. By eliminating the transformers and super expensive tubes, a huge cost saving is achieved. The Transcendent Sound Single-Ended OTL amplifier is designed to outperform other single-ended amplifiers that cost many thousands of dollars. It is not a strip-down or budget-performance model. The cost savings are passed on the consumer with a much lower price. That's not perceived value, that's real value.
5) No Adjustments Ever: The sophisticated circuitry used in the amplifier has completely eliminated the need for any bias or balance adjustments. No meters to watch, no knobs to turn, no calibrations of any kind, and best of all, no worries. Just turn it on and enjoy your music.
6) Incredible Musicality: Audiophiles have known for years about the smooth, natural performance of single-ended amplification. By combining single-ended characteristics with OTL circuitry, a higher level of music reproduction has been achieved that is impossible to obtain with any other technique. This isn't High-End audio, this is the Highest-End.
7) Wide Speaker Compatibility: Not just for horn speakers! The amplifier has ample power for driving any 8 ohm high-efficiency speaker with a sensitivity of 95 dB at one watt. Power output increases with speaker impedance. At 12 ohms, it outputs 2.25 watts and reaches 3 watts into 16 ohms. It therefore can drive 16 ohm speakers with a sensitivity of just 92 dB at one watt.
8) Bridgeable: Need more power? The amplifier can be bridged from the outside of the chassis with no internal wiring changes if desired. Just use a Y connector on the input and connect a short jumper wire across the binding posts. Power will then increase to 4 watts into 8 ohms. This is enough power to sensibly drive 8 ohm speakers with an efficiency as low as 92 dB with one watt. Two amps will be required for bridged operation.
The output stage uses the rugged, great sounding and low cost 6C19pi triode. This tube has proved to be extremely reliable and consistent in our model T16 amplifiers. It is most dependable tube for OTL use without exception. Four are used per channel. A simple current sharing feature balances the load between all four. They are operated in a fully Class A, single-ended mode. There is no possibility of DC getting into the speakers as the output is AC coupled through a blocking capacitor. There is absolutely no possibility of any damage to your expensive speakers.
Massive inductor/capacitor filtering is used to supply the output stage with ultra clean DC current. Over 11,000 microfarads of capacitance is used in the power supply. Highly refined and sophisticated techniques have been employed to reduce noise levels to very near theoretical minimums. Like the old saying goes, "It just doesn't get any better than this." Well, in this case, "It really can't get any better than this." Power supply performance has been pushed to the limits off what is possible to obtain without spending thousands of dollars. Any further improvements would be totally inaudible.
The driver stage uses the magnificent 6H30pi tube. The big low impedance triode is the most linear voltage amplifier on the market. It easily drives the output stage with very low distortion. In, fact, total harmonic distortion is only about 0.7% maximum.
Gain is set at 9 dB. This is perfect for high efficiency speakers when driven from an active preamp or high level source. The Grounded Grid Preamp with a gain of 12 db, super quiet, and wide bandwidth is an ideal match. Operating the amplifier from a slower, noisier preamp will reduce performance.
The amplifier has the same footprint as our Grounded Grid Preamp, Phono Stage and Balanced Power Supply. They all match and are designed to work together as a complete system. The case is 15 inches wide and 10 inches deep.