Audio Horizons TA 18 SET tube amp

http://www.audio-horizons.com/pages/TA18.html

Audio Horizons’ First Amp—A Lovely NEW SET Amp

Now after six years, Joseph Chow introduces his first amp, a superb SET amp of stunning sonic beauty and clarity.

How fine is this amp? So fine that the first pre-introduction auditioner—an owner of a 150 wpc Mark Levinson 27.5 amp that he had spent several hundred dollars having Joseph extensively upgrade, bought one on the spot. Here are Drt’s unsolicited comments after he took the amp home:

“The TA 18 Tube Amp really sounds great. I thought the Mark Levinson 27.5 which you extensively upgraded for me was already outstanding. But the TA 18 is significantly better than the ML 27.5 or any other amp I have heard, up to $20,000. It truly transforms the sound of my system, making it much more natural, open, very pure sounding and just really musical. Of course it is a perfect match to the Audio Horizon Tube Preamp. But it does wonders for solid state preamps as well.

“It even made my Proceed AVP-2 processor sound much more musical even without the Tube Buffer [The Audio Horizons TB 5.0cv].

“If people still like a solid state preamp for convenience (remote control of volume, changing inputs, programming settings, etc.) I highly recommend matching it with this tube amp to bring more warmth, musicality, naturalness and just aliveness to the music."

If you would like more information about the TA 18 please visit our website at the address above. Highlight the web address above and then right click your mouse and it will provide a direct link to our website.

The TA 18 comes in two versions, a basic 8 ohm TA 18 version with somewhat smaller transformers, and a more sophisticated 4 or 8 ohm TA 18b version with more options and larger transformers capable of delivering about 25% more power and high Sound Pressure Levels without clipping.

Like all of Joseph’s components, the TA 18 is very open and transparent sounding, with excellent bass, a finely textured high end, and a sweet smooth midrange.
Because this amp is a SET amp, it performs like a push-pull amp with a power rating four times higher than its nominal rating—5.5 watts per channel in the basic version, 7 watts per channel in the more sophisticated higher powered version.

Like all of Joseph’s designs it has excellent bass--surprising in its power for such a low powered amp, and for its power rating remarkable dynamic headroom. Over Joseph’s 89 dB Wilson Sophia speakers in his 13’ x 26’ x 9’ LR we had no trouble playing a large orchestral work like Scherazade at 90 dB without strain, compression or breakup.

In order to see how loud the TA 18 would play we designed the following test: we set up out test equipment 1 meter from Joseph’s 89 dB Wilson Sophia speakers and ran a test signal through the speakers until just before the amp went into clipping. The Sound Pressure Level registered 93 dB in stereo. We then played a superb recording of Rachmaninov’s Symphonic Dances, which has a lot of deep bass energy to see how the amp performed music at this sound pressure level. Frankly, other than sounding too loud, it sounded wonderful, with plenty of bass energy and no sense of dynamic compression. Then we turned the dial up a turn, and sure enough everything fell apart as the amp went into clipping. Thus the test and our experience of a live performance reinforced each other. This amp, on speakers of moderate sensitivity, will play plenty loud without any loss of bass energy or any sense of dynamic compression.

But words will only convey so much. You have to hear this amp to believe what it can do, which is why as with all our components we offer customers an opportunity to audition the TA 18 at home over their own sound system FREE.

The TA 18, with oiled oak wood sides, is priced at $4295, and the larger more sophisticated TA 18b is priced at $5500. Add $395 for balanced mode. But now, in celebration of the introduction of Audio Horizons first amp and in order to gain the widest exposure for this amp, between now and June, we are offering the TA 18 to customers for $3295 and the TA 18b for $4250. Add $350 for balanced inputs as well as RCA inputs.

Special Features

Like all of Joseph Chow’s designs, the TA 18 is a zero feedback design, resulting in sound that is extremely open, transparent and dynamic. Again, like all Joseph’s designs, the TA 18 uses only Hi Q materials. For example:

• The wiring employs only Hi Q wire and is point to point throughout for a more direct and transparent circuit design.
• The coupling capacitors on the TA 18a are polypropylene for much greater transfer efficiency, and on the TA 18b, film V Caps.
• On units ordered in balanced mode, the input connectors are Neutrik RF shielded.
• The tube sockets are made of Teflon and have machined gold pin contact points for superior conductivity.
• Premium quality output transformers
• The speaker binding posts are heavy duty and made by Cardas.
• The TA 18a and TA 18b come with a Furutech gold plated IEC plug and for smoother performance, on the TA 18b we have installed the highly rated HiFi Tuning fuse.
• Finally, in order to extend the life of the tubes, the TA 18 employs a soft start on the high voltage.
• Additional Refinements include:
o high voltage filter employs a choke
o Point to point star grounding
o Indirect HV tube rectifier to prolong the life of all tubes and power capacitors
o Hi quality hot wiring throughout
o Expensive solid silver-copper bi-metal wiring in signal input paths (18b only)
o AN silver RCA jacks in the TA 18b and gold plated Teflon jacks in the 18a for superior performance
o Acme cryoed fuse holder
o Premium rotary power switch
o Welded chassis for most solid resonance control
o CNC solid panel.
o Optional upgraded tubes and performance enhancing tube shield-dampers are available for a modest extra cost

But finally, audio is about sonic performance and not about features or specs. These are mere indications, but never definitive. So how does the TA sound? The answer: Lovely. And more powerful than you ever imagined a low powered amplifier could.

But the TA 18 is not for everyone. If you speaker is 87 dB or less, or if your room is very large—say larger than 14’ x 27’, or if you like to listen to music at 90 dB all the time, then the TA 18 may not be for you. But if your speaker sensitivity is 88dB or higher, if your room is medium sized, and if you are comfortable listening to music at 85 dB or less, then you really should listen to this superb new amp by Joseph Chow. You’ll be surprised at how beautiful it sounds—and how big.

Free Audition Program

To ask for a free 10 day home audition, you must have an Audiogon positive score of 30 and no negatives. Or you can purchase the TA 18 on Audio Horizons’ freight prepaid 20 day money back guarantee. If within 20 days, you decide the TA 18 is not right for you, ship it back to Audio Horizons and we will, no questions asked, refund your full purchase price.

Specifications

Power rating:
TA 18 5.5 Watts per channel
TA 18b 7 Watts per channel
Impedance:
TA 18 8 ohms only
TA 18b 4 or 8 ohms, by accessible jumper spades
Voltage gain: 22 dB
Frequency response at -6 dB point:
TA 18 20 Hz to 60 kHz, +0, - 3dB
TA 18b 5 Hz to 45 kHz +0, - 3 dB
Total Harmonic Distortion:
Less than 1.3% at 1 kHz
Less than 1.5% at 25 Hz
S/N ration: 87 dB
Noise floor: Less than 0.3 mVrms
Dynamic range: 75 dB
Tube complement: 6EM7(2), EL34(2), 5AR4
Self biasing or fixed bias.
Voltage: 120 volts 60 Hz
Dimensions: 17” w x 8.5” h x 11.5 » d
Weight: 30 lbs