Transcendent Sound       Vacuum Tube OTL Audio Amp Kits

♦ 1 Watt Stereo-4 Watts Bridged

♦ Dead Quiet

♦ Unbelievable Clarity and Realism

♦ Simplest OTL Circuit

♦ No Bias Adjustments Ever

♦ No Calibration Required

♦ Much Lower Heat

♦ Top Performance- Entry Level Price

The New Mini Beast

Pure Single Ended Class A OTL

Full Kit $649, Two for $1199 Without Tubes

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The original design has been completely revisited.  It has been made simpler, very easy to build, much lower cost, and quieter.  Distortion levels are very low.  There is nothing to adjust or go out of calibration.  Heat has been dropped to only 180 watts which is much easier to live with.   Perfect for use with Horns and Ear Speakers.  Also excellent for use in smaller rooms with more typical speakers.    

The design went from three tubes per channel to two and the idle current through them has been reduced which will allow them to last much longer.

Consequently, power has been reduced but most people use these types of amps with speakers that only require one watt.  Power doubles into 16 ohms and distortion cuts in half.  It does surprisingly well with 8 ohm speakers with a 95 dB sensitivity such as the Tangband designs shown on this website.  To maximize performance, we have designed a low cost 16 ohm matching speaker that you can build.  Full plans are here.  This is a top performing speaker that works extremely well with all Transcendent Sound amps.  Coupled with this amp, fairly large rooms will be filled with sound.  If more power is desired, the amp can be bridged into mono which will yield 4 watts into 8 ohms and 5 into 16.  (Power does not double in bridged mode because the amp runs out of voltage.)  If you build the matching 16 ohm speaker, monoblocks will not be necessary except in very large rooms.

Transcendent Sound has always strived to bring the audiophile top notch performance at low, affordable proces.  Mating the new Mini Beast with the Slider, building the Raspberry Pi DAC and the matching 16 ohm speaker, will create an outstanding system for less than $3000.  In todays Hi-end world, that is a super bargain.

The most critical parameter for an amp like this is noise.  Sensitive speakers not only reveal the delicate nuances of music, they reveal any system noise.  Here is a plot of the A weighted amp noise with no input into 8 ohms.


Notice that the bulk of the noise lies below the 12.5 micr0volt RMS line.  (On this program "n" means microvolt.)  This is well below detection.  The largest noise spike is 56 microvolts at 180 Hz.  This is the the only noise component that may be possible to detect.  The second biggest spike is at 60 Hz at 47 microvolts, too low to hear and most of that is ambient noise bleeding into the test setup.  The program calculates a net full bandwidth noise of 142 microvolts, but that is misleading becase it is spread out over the full bandwidth.  The noise is vanishingly low.  

Above is a plot of harmonic distortion with 5.5 volt PP, 1 kHz fundamental, 0.5 watt into 8 ohms.  The peak is at the third harmonic at 14.66 millivolts.  That's 0.26 %.  The next is at fourth harmonic at only 5.6 millivolt which is 0.1%.  Into a 16 ohm load, distortion products are basically cut in half.

The amp is blazing fast.  This is a plot of a 10kHz square wave at 0.5 watt into 8 ohms.  There is no ringing or overshoot.  Below is a plot of a 200 kHz sine wave at 0.5 watt.  The amp is flat from 20 Hz to well beyond 200 kHz.


Power output- 1 watt/ch into 8 ohms.  2 watt/ch into 16 ohms, 4 watts bridged into 8 ohms.  5 watts bridged into 16 ohms.

Signal to noise ratio- greater than 86 dB into 8 ohms and 90 dB into 16 ohms referenced to one watt.  See above for greater detail.

THD- less than 1% at one watt into 8 ohms and 0.5% into 16 ohms.

Bandwidth- flat from 20 Hz to beyond 200 kHz.

Gain- 12 dB or 4 times.

Minimum signal required for 1 watt into 8 ohms- o.7V RMS.                  For 2 W into 16 ohms, 1.4 V RMS

Output Impedance- 2 ohms from 50 Hz to 20kHz, rising to 3 ohms at 25 Hz.

Power consumption- 180 watts.  115V or 230V, 50-60 Hz

Tubes- 4-EL509 and 2-ECC99.  Matched output tubes preferred but not necessary

Size- 10 by 17 inch footprint.

Weight- 18 pounds