Transcendent Sound

Making Music Better



Nothing sounds better than an OTL.  No transformer coupled amp, no solid state amp can match the sound.  It cannot be imitated.  Striking imaging causes instruments to be layered in a three dimensional sound stage that recreates the experience of a live performance. The music "opens up" and leaps out of the loudspeaker eliminating any box like sound. The most minute and subtle sounds are revealed producing uncanny realism. Musical voices are warm and lifelike yet completely neutral with a razor sharp focus. Nothing else can compare.  Don't just listen to your music.... experience it.

In an OTL, the loudspeaker is directly coupled to the output tubes. There is no output transformer.  There are many practical limitations that have kept the transformer-less output from becoming widely used. Our patented design has finally solved all of these problems.

Low power OTLs are much more difficult to design than high power units, especially when low cost must be maintained.  Bass performance is where low power OTLs have traditionally been deficient.  Not this one.


By applying patented Transcendent Sound technology, this amplifier has no reduction in bass performance.  It maintains all of the slam, punch, and transient attack that Transcendent amps are famous for in a lower power, low cost configuration.  We have eliminated the characteristic "weak bass" and "light weight" sound that plague other OTL designs. The amp has a solid bottom end with lots of punch.  Output impedance measures a low 1.0-ohm (0.7 ohm for monoblocks), allowing it to easily drive 8-ohm speakers.

See article on importance of low output impedance

The output tube used is the Russian military 6C19PI.  This is a 9-pin miniature base triode.  Tube consistency and stability is high making it suitable for a kit application.  It’s rugged, inexpensive, and best of all, has great sound, particularly in the bass region.  Tests were run with the 6AS7G and it was found to be unable to produce the sharp transient attack required for the best performance.  Percussive sounds were rounded off which was unacceptable.  The 6C19PI, on the other hand, does not exhibit these shortcomings and equals the bass performance of the EL509.  The midrange and high frequencies are likewise lightning quick with all of the detail and realism of live music. 

Not only is the performance there, this kit is easy to build.  All circuitry is on printed circuit boards.     This is additional value that Transcendent Sound gives its customers, saving your time and helping to ensure a satisfactory project.

The chassis is a very attractive, heavy duty (18 gauge) brushed stainless steel.  Most other manufacturers supply kits with a thin, painted steel chassis.  The front panel is hand brushed aluminum.  These features provide a great appearance that will never deteriorate at an affordable price.     

All driver stages have their own separate voltage regulation for each channel.  Bias supply is regulated and incorporates an improved adjustment allowing for a wider tolerance of output tube variations.  Separate output stage fusing makes finding a bad tube much easier to do for simplified maintenance.  Power supply incorporates a two-stage inductor/capacitor filter section for lower noise.  Separate power transformers are used for filament, output stage, and driver circuits.  Soft start eliminates the hammering of current-inrush thereby protecting internal components.  This amp is built to last.

The idle current for the amplifier is only 1.6 amps!  This is no more than many solid- state amplifiers.  It can be operated in the hottest climates with no discomfort.  The waste heat output is less than two-100 watt light bulbs. 

See article on OTL class of operation, A or AB

Ultra Low Noise Upgrade



By adding a second choke/capacitor filter section, the signal to noise ratio can be improved to over 95 dBA.  This makes the stereo amp perfectly suited to drive the highest efficiency horn speakers available.   The upgrade is highly recommended for the stereo amp.  Customers with speakers that have over 93 dB sensitivity should consider the upgrade.  The upgrade can be added at any time.

The amp has a small footprint of only 10 inches deep and 17 inches wide and fits on many bookshelves.  Now people who live in small apartments can enjoy OTL performance.  Also, the chassis is designed to accept a standard 10-inch by 17 inch Hammond cage (optional-not included) for those customers that require one.  The amp fully protects itself and your speakers from any possible component failure.  There is nothing to worry about.  Bias is very stable and rarely needs adjustment.  Just plug it in and use it. 


Stereo Unit
Voltage: 110-120V, and 220-240V, 50-60 Hz.
Power Output:  15 watts per channel into 8 ohms, 8 watts into 4 ohms 
THD: 1.0%
Output impedance: 1.0 ohm
S/N ratio: 85 dBA,  with Ultra Low Noise Upgrade: 95 dBA
Bandwidth: -3dB from 5 Hz to 60 kHz
Gain: 20 dB

Tube compliment:

Voltage: 110-120V, and 220-240V, 50-60 Hz.
Power Output:  40 watts into 8 ohms, 25 into 4 ohms.
THD: 0.5%
Output Impedance: 0.7 ohm
S/N ratio: 90 dBA, with Ultra Low Noise Upgrade: 95 dBA
Bandwidth: -3dB from 5 Hz to 60 kHz

Tube compliment:

Size overall:  17 1/2 wide by 11 1/2 deep by 6 1/4 inches high
Size overall with optional lid:  17 1/2 wide by 11 1/2 deep by 9 inches high
Weight: 21 pounds, with optional lid 25 pounds
Shipping Weight: 25 pounds each unit.
Protected by U.S. patent  5,604,461


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Outstanding Bass

Very Low heat

Solid Reliability

Incredible OTL Sound





Optional Lid- Not Included

Available from any Hammond Dealer.