This phono preamplifier was among those heard in a phono preamp comparison conducted by the San Francisco Audiophile Society in April 2015. Eleven phono preamps were heard, including excellent products such as ARC Reference 2, Zesto Audio Andros, Pass Labs XP-15, Merrill Audio Jens, and others. An opportunity for such comparison is extremely rare. The TP 8.13 musical performance stood out in this company.
Audio Horizons (AH) is a company that, for nearly 20 years, has created audio electronics and accessories which deliver the highest quality music playback. AH tube amplifiers are renowned for their low noise and wide frequency range, revealing the dynamics and the subtlest harmonies of the recorded performance.
AH products are designed to adapt to user system requirements . This particular phono preamplifier has been a platform for AH product development and testing. It incorporates the latest level TP 8.13 revisions of its features. It delivers outstanding resolution, soundstaging, and musical performance - a sensitive and readily integrated match to your turntable and amplification.
The power supply, always excellent in AH products, uses Mundorf film capacitors and multiple loaded chokes to deliver a smooth, ripple free high voltage supply to the filament and plates. Tube life is extended by a constant filament current supply. Current is rectified through an EZ80 tube, used also for a soft start cycle to allow the unit to power up fully before passing signal.
V-Caps (copper film type) couple the DC supply to AC. The output tubes (x2) are Siemens ECC88. RIAA equalization is achieved passively at +/-1 dB precision. An Audio Horizons Platinum Reference fuse (see http://www.10audio.com/audio-horizons_platinum-ref-fuses.htm) is used in the 120V circuitry. The internal wiring is in premium Mundorf wire.
The rear panel of the AH has two RCA female receptacles for MM input and two RCA female receptacles for MC input. The inputs are selectable by the toggle switch located between them. The selectable inputs allow you to connect two cartridges (an MM and an MC) on separate tonearms. Vishay metal film resistors accurately set the MM input impedance at 47K ohms. The MM section delivers 41dB of gain.
Two Lundahl LL9206 step-up transformers are on board for low gain cartridge amplification. The LL9206 is an amorphous core transformer. The amorphous core material does not store energy and rejects low frequency resonances. LL9206 frequency ranges are extended and the tolerances are tight: +/- 1dB from 10 Hz to 25 kHz +/- 1.5dB from 10 Hz to 90 kHz.
The Lundahl LL9206 can be wired to three different turns ratios: 5:1, 10:1, or 20:1, which provide gains of 14dB, 20dB, and 26dB respectively. In this unit the LL9206 is wired to a 10:1 turns ratio (20dB gain). This phono preamplifier is wired at the 10:1 ratio presently.
The impedance loading of your phono cartridge can be set precisely. The back panel of this unit has two female RCA receptacles wired to accept resistor loaded male RCA connectors as a joint impedance load with the step-up transformers.
I can provide a table of calculated values for the three turns ratios which will guide you to select the best resistor value to match the requirements of your cartridge. I'm ready to work with you to create a proper impedance load match for your cartridge.
If you have a favorite outboard step-up transformer you will be able to use it, too, with this phono preamp.
The TP 8.13 is a first rate phono preamp that will integrate readily into your system and improve its performance substantially. With it, you can enjoy the full performance of your turntable, tonearm and cartridge.