September 2004

Ayre K-1x Pre-Amplifier With Phono Stage
A Formula 1 Race Car
Review By George Papadimitriou (Pappas)
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  What is this, a tube lover reviewing a solid-state pre-amplifier? Absolutely! The reason I decided to do a review on the Ayre Acoustics K–1x is that for a few years I have owned an Audio Note Meishu phono integrated 300B amplifier that produced eight watts per channel. This has provided me with great sound, as well as plenty of enjoyment throughout the years. However the tubes go bad, the tubes arc, and the most frustrating part is that sometimes the gain of one tube is higher than the other thus resulting in an off-centre stereo image. (Editor Steve sez: Time for George to pony up the Canadian dollars and get properly matched high quality tubes, eh?). Maybe it’s my age (50), but I want to tweak less and listen to music more so I decided to give the K-1x a listen. I was very interested to see how good solid-state has become compared to about a decade ago.

Send The Unit Over, Gary!

So I placed a call to Ayre Acoustics and spoke to Gary Mulder who is a sales and marketing guy of the company. Gary was absolutely wonderful and a great pleasure to deal with. He was very helpful and knowledgeable, not only about Ayre Acoustics products, but about audio in general. If the rest of the people at Ayre are as accommodating as Gary, the entire company must provide great customer service.

The K-1x is Ayre’s top of the line pre-amplifier and can be purchased with or without a phone stage. The small "x" represents the latest update. All of Ayre Acoustics’ products are fully balanced designs from input to output and have no feedback in the circuits. The phonostage inside the K-1x is an option as is the remote control. By the way, the remote only performs a few of the functions and thus is not a full-featured unit. It controls volume up and down, mute and switches on/off the companion V-1x power amplifier.

The most interesting feature about this pre-amplifier is its stepped attenuator volume control, which is located directly on the circuit board. This control is a Shallco-type attenuator with 46 discreet settings. Because this is a fully balanced design, there are four of these stepped attenuators all connected with a series of belts and wheels that enables one volume control to turn on all the four attenuators. The stepped volume control has unity gain when the volume control is ten steps below the maximum setting, roughly at the 3 o’clock position of the volume control.

Controls And Features

The Ayre K-1x comes in two pieces, the main unit as well as a separate power supply. The main amplifier is housed in a heavy-duty (mostly aluminum) case that is very sturdy, well made, and appears to have minimal resonance. The philosophy of Ayre is to create products that are very minimal in features in order to preserve the greatest amount of fidelity. The front panel, therefore, has just the basic features. There is the main volume control that activates the stepped attenuators mentioned above, a "listen" as well a "record" knobs that are self-explanatory. At the right of the front faceplate there is the infrared remote control receiver followed by a mute button and then a status indicator lamp. The indicator light glows red for a warm-up, green for mute and blue for listen.

The K-1x also has three pairs of balanced inputs (XLR) and three pairs of unbalanced inputs (Cardas RCA). If the phono option is chosen, it connects to one of the balanced inputs, namely input number two. This pre-amplifier also has two sets of balanced outputs as well as one set of unbalanced outputs. The manual states that the unbalanced outputs is 6dB down as compared to balanced and also inverts the absolute polarity. If you are using the unbalanced RCA outputs, a good suggestion is to reverse the loudspeaker leads. If there is not enough gain in stock form, an authorized dealer (or the factory) can increase the gain of the K-1x.

Built-In Phono Stage

The optional phonostage accepts XLR balanced inputs only. The manual states, "as the phono cartridge is an inherently balanced device, the phonostage is also balanced, using XLR jacks at the input." It goes on to say that since most phono cables are terminated with unbalanced RCA’s, you have two options. The first one is to use RCA to XLR adaptors, available from Ayre, and the second option is to convert your phono cables to XLR connectors. The manual says that the latter is, "the preferred solution and offers the highest level of sound quality." Because my cables have RCA connectors, Gary Mulder sent along the RCA to XLR adaptors for me to use. He stated that he has tried this himself and the connectors that they make little effect on the sound. This then, was how I used the phonostage for this review.

This phonostage is extremely flexible in that it allows you to use one of three gain settings as well as to configure the resistive loading to almost any value. The gain of the phono stage can be either set for 40dB, 50dB or 60dB. Removing and reinserting the appropriate gain resistors on a small terminal block on the actual phonostage board changes the gain. The resistive loading is adjusted by inserting the appropriate resistor in another terminal block. Several loading resistors are included (100, 249, 499, 1,000 and 50,000 ohms) and you can also specify any other loading resistors to suit your needs. The Ayre K-1x pre-amplifier includes a transferable warrantee against defects in workmanship and materials for a period of five years from the date of the purchase.

How Does It Sound?

The first thing I noticed about the Ayre pre-amplifier is that it is like a Formula 1 racing car. It is very sensitive to setup, cables, support feet, as well as components upstream and downstream. It is also very sensitive to A/C plug orientation and, to my ears in my system, sounded better (sweeter, less strained and edgy) with the polarity reversed. I have added many plugs, all in a row, and have wired some of those plugs with reverse polarities so I do not have to use the dreaded cheater plugs. This allows me to hear the difference between reversed and normal polarity without the sonic degradation of the cheater plugs. The K-1x can sound a little stressed, strained, and a touch harsh and irritating to listen to if not set up correctly. This is not to criticize the unit in any way. The fact that you can hear the difference between interconnect cables or support feet so quickly and so easily is a testament to the transparency of the unit. Minute changes in setup or associated components make a larger-than-average difference. In that way it is like a Formula 1 racing car, where small changes in the suspension or the tires, or several other factors, make a dramatic difference to the performance.

I Tried Several Setups

Because this unit is sensitive to setup, this makes it easier to select power cords or establish the best feet support for the unit, and all this can be heard very quickly -- sometimes in a matter of fifteen seconds.  The Ayre K-1x is that transparent. I’ve tried several types of the feet to support the K-1x preamp. I’ve tried the smaller Ayre myrtlewood blocks, which are made by Cardas by the way, for Ayre, the large Cardas myrtle blocks as well as the K-1 x’s own feet, and finally I tried it on a small bicycle inner tube which sort of float the unit on air, so to speak. This is a very cheap version of an air suspension system, and even though it sounds very hoaky, it is very effective for about the cost of three dollars for a bicycle inner tube.

The sound of the Cardas large myrtlewood blocks and the smaller Ayre myrtlewood blocks are very similar. Generally the sound was more open with a higher frequency extension. However, there was a noticeable spotlighting of the upper- mid and high frequencies, making the music a little thinner but more open, sharper focused, with better-defined images. On the other hand, this was at the slight expense of musical ease, naturalness, warmth and an integration of the harmonics and the fundamentals. There was also less meat on the bone, so to speak. Less warmth, less body. Using this preamp on its own feet produced a sound that was less sharp and less focused, slightly smoother with a greater ease to the music and harmonically more correct. The entire musical tapestry seemed to move down in pitch and frequency, which gives the music better body, a blacker background and generally made the music easier to listen to.

How About The Inner Tube?

Suspending the main preamp on the above-mentioned inner tube gave more of the sonic effect of using the K-1x with its own internal feet. It produced an even blacker background and a more natural, warmer presentation. As well, the soundstage was more expansive with greater instrumental hall decay. All of this is to point out to you that the K-1 x preamp is very open and transparent and is very sensitive to setup. The advantage of this is that you can actually dial in a sound to match your listening preferences as well as to match with the rest of your system. I noticed that with all the above feet treatments, when the energy of the music was at a crescendo as well as when voices were really belted out, the preamp had a very small tendency to break up, like the preamp was not better damped. I noticed this tendency more with the myrtlewood blocks and less so when the preamp was supported on an inflated inner tube. Perhaps placing this preamp on a full "Bright Star" support system, which includes a damping of the chassis both at the bottom and the top as well as the whole unit being supported on air, would severely reduce or eliminate this tendency. I’m only speculating here.

A/C Line Quality

The K-1x was also very sensitive to the quality of the AC line coming out of the wall. I noticed that later at night the sound was much more natural and substantially less stressed. This is because later on in the evening the quality of the AC is generally better and this is certainly the case in my house in Toronto. Earlier in the day, the sound was noticeably sharper and harsher with an edge to the music between the afternoon hours of 4 PM to 7PM.  This is generally when electricity consumption is at its highest and therefore the quality of the electricity is at its worst. After about 10 PM, the quality of electricity in Toronto improves substantially and listening to the Ayre K-1x preamp after this time was very enjoyable, very engaging and very involving. Substituting a warmer, richer power cord also helps here. When I substituted the Cardas Golden Power Cord I noticed that it smoothed out the sound and the musical presentation was warmer and less harsh sounding.

Lots of Ayre

The real strength of the Ayre preamp is contained in its name.  The sound was very open, very airy, and very transparent. The soundstage was h-u-g-e and the front to back depth was extremely well extended. The whole soundstage and the performance were so incredibly open, wide and deep. It was almost holographic. If you are a lover of walkaround imaging and soundstaging, this may very well be your preamp. I have never heard a solid-state product be as open and with a huge soundstage as this preamplifier. It rivals, and in many cases exceeds, the soundstaging of even a really good tube preamp in my experience. In fact the sound stage was more open and definitely better defined with more air and space between the instruments than even some of the best tube units. The openness and the incredible 3D soundstage of this pre-amplifier was noticeably and substantially increased when it was partnered with its brother, the Ayre Acoustics V-1x power amp. This combination produced probably the most open, gigantic sound stage that I can remember hearing. For your information, the V-1x power amp is also fully balanced from input to output and uses no negative feedback as well. It produces 200 watts per channel at 8 ohms, which is plenty of power to drive most rationally designed loudspeakers on the market today.

Another strength of the Ayre pre-amplifier is its speed and quickness and its great renditions of the attack and leading edge of the music. The attack notes, whether from a trumpet or a snare drum, for example, are quick, tight and fast and have great pace and energy. On the other hand, the music is not as fleshed out as some other preamps. The music has less weight, less body, less meat on the bone, so to speak, than other preamps, for example the Jeff Rowland Synergy IIi. With the Synergy Iii, the music is less open, less airy, but there is a warmer flavor to the music with more mass and body to the sound. The Synergy was, most of the time, easier to listen to, had a more relaxed, more calm and less stressed quality. This sound quality is, to a large extent, a personal preference. The Synergy also produced a less direct, more distant presentation of the music.

The K-1x is the more transparent, more direct, clearer and more open of the two preamps. The Synergy IIi was quieter, less grainy, and produced very dark backgrounds because of its incredible quietness and lack of noise. Here’s an example: on the Jacintha album called "Autumn Leaves", with the Jeff Rowland the drums were deep, full, and had excellent weight. The quick hits on the drum however, were somewhat muted and did not have those quick, lightning-fast shots that that the K-1x so easily produced.  However, the K-1x doesn’t reproduce the actual drum skin sound or the resonance of the drum barrel as well as the Synergy IIi. Also on the same disc, the piano had better mass, body, power and energy with the Jeff Rowland preamp. Alternatively, the K-1x produced better instrument attack, better percussive effects and a more realistic sound of the guitar.

The Jeff Rowland Synergy IIi is the warmer, more yin-like of the two. The Synergy is a cinch to set up and it is way more forgiving in its setup. Yet you can still hear the differences in setup, cables, AC orientation, but it is always easier to listen to. It is a better late night sounding preamp, so to speak. Also with the Synergy IIi, the mid-range and the lower mid-range have more energy and volume which gives weight and impact, mass and solidity to the music. On piano, for instance, you hear the power of the instrument, its weight as well as the resonance of its wooden frame and body. However, the K-1x counters with the attack of the instruments being quicker, faster and the leading edges of the music are better reproduced, while these are someone softened by the Synergy IIi in comparison to the K-1x.

Overall, I would say the Jeff Rowland preamp sounds closer to the sound of good tubes. It is more relaxed, a touch laid back and a little indirect. Its very low noise floor allows you to hear small influctions in the music very easily. The K-1x sounds closer to a  state of the art solid state  product  in that it has great clarity, transparency and a directness to the music. The K-1x produces better clarity as well as greater energy and drive to the music. The K-1x is generally, and I do mean generally, better at pop music, blues and jazz and in general, and I do mean in general, the Synergy IIi is better suited for symphonic works, folk and softer jazz music.

Playing Around With Cables

Because the K-1x is very transparent or very revealing, the choice of interconnects and loudspeaker cabling make a larger than normal difference in the sound of this product. You can, to a great degree, dial in the sound that you like by substituting a different interconnect into the system, for example. I found by substituting an interconnect which is a little warmer, sweeter and easier to listen to, I could tailor the sound of the K-1x to be closer, but not the same as, the sound of the Jeff Rowland Synergy IIi preamp. When I installed the Cardas Golden Cross interconnect, the slight audible grain in the K-1x was dramatically reduced. The preamp now became easier to listen to, slightly (and I do mean slightly) less direct and transparent, but overall the sound was more relaxed and less stressed sounding. You can finally go "ahhhhhhhh" and sink into the music and relax and be moved by the music as opposed to being somewhat antsy and unsettled.

With the Cardas cable, I also noticed that there was more body to the mid-range and upper base providing more substance and mass to the music. There was more meat on the bone, as I said before. For most people, I believe his is a good compromise between easy to listen to and clear and transparent.  The point here is you can tailor, to a large degree, the sound of this preamp. I got the same benefits, although to a lesser degree, when I installed the Cardas Golden Reference interconnect.  The Golden Reference is more airy, more open and more extended than the Golden Cross, however, it does not have the Golden Cross’s body, warmth and sense of weight to the music. Also, I found that the Golden Cross is more cohesive and continuous from top to bottom. The integration of the music is better than with the Golden Reference.

Using an A/C Power Filter

The people at Ayre Acoustics advise to plug the preamp directly into the wall. As a comparison, I also tried the Foundation Research LC1 power cord with its own built-in filter. This power cord is designed as a combination power conditioner as well as a power cord, only serving one component at a time.  With the LC1 used as a power cord on the K-1x there was a greater easiness to the presentation. Brass sounds took on more of the warmth of that instrument and not just the quick attack and bite. There was also better separation of the instruments and a sense that the music just "settled in". The sound generally was not as clear or transparent as without the LC1, but the music was sweeter, less stressed and more relaxing to listen to. For example, Andrea Bocelli’s voice had a greater chest, throat and head contribution, not just singing that comes only from the mouth (Andrea Bocelli, Sogno, Polydor, 547222-2). With this power cord/conditioner, there was less breakup and harshness of the sound when the music really got loud or when the singer was really belting out the tunes. Substituting the Foundation Research LC1 power cord/filter is another example at fine-tuning the sound of this preamp to better suit your system and your sonic preferences.

With the LC1 installed, at first listen, the transient seemed more softened and the clarity of the music did not seem as good, the immediacy was reduced. However, after extended listening, I had the opinion that this transient speed, clarity and immediacy were likely artifacts or colorations to the music due to the noise of the AC line. After longer listening sessions, the music just felt more natural and less hi-fi-ish with the LC1 power cord/conditioner.  One drawback of the LC1 was that the bass was not as deep as it was using the Cardas Golden power cord, for example. Also, the dynamics and the oomph and punch of the music were somewhat less than with the Cardas Golden  power cord.

Even though the people at Ayre Acoustics suggest you plug their K-1x preamp directly into the wall receptacle, I suggest that you, at least, try  plugging the unit into a really good power conditioner or the Foundation Research LC1 power cord/filter combination. One of the things that is unique to the Foundation Research filter is that it is a two-way filter which filters not only the electricity coming into the component, but also filters the line going back from the component into the wall as well. This prevents noise that is generated by the component to be greatly reduced as it goes back into the wall socket to feed the other components. In the final analysis, try different power cords, try different interconnects and speaker cables as well as feet and supports to tailor the sound to your liking.

Final Wrap-Up

I believe that the Ayre Acoustics K-1x preamp is a world-class solid-state pre-amplifier. It is one of the best preamps I have heard. It has the advantage of also having an optional phono stage that is also first-class. What this preamp does with soundstaging as well as presenting an airy, open, clear quality is absolutely astounding. It is probably the most open, transparent preamp that I have heard and it produces a h-u-g-e soundstage. The soundstage extends well beyond the outside of the speakers and also has great front to back depth. There is a sense of immediacy and clarity that, at times, it feels like there is a real person and a real band in the room. This preamp also excels at speed and quickness. The attacks of the instruments are quick, fast and articulate.

These great strengths come at a slight cost in warmth, musicality, as well as ease of presentation. There is also a slight, and I do mean slight, sense of grain and transistor harshness to most of the music most of the time when the music gets loud, especially to vocals when the singer is belting out the tunes. Some listeners will prefer the clarity, transparency and openness of the sound and won’t be affected, as much, by this preamp’s slightly drier, slightly more analytical presentation. You can also substitute a really good power conditioner, a good power cord, as well as different interconnects and loudspeaker cables to bring the sound of this preamp to a closer match with your components and your listening preferences. The comparison between the Ayre K-1x versus the Jeff Rowland Synergy IIi preamp is very interesting. The K-1x is like a Ferrari sports car, quick, nimble responsive, and precise. The Synergy IIi, on the other hand, is like a Jaguar XK 8 sports car which is a little bit rounder, a little bit softer, smoother and more relaxing to drive. Both of these cars are excellent, just different.

All in all, the Ayre Acoustics K-1x is an exceptional preamp. Its fully-balanced, no negative feedback circuitry makes it very open, clear, transparent, and allows the music to come through with the realism and clarity very close to the real thing. Well done, Ayre Acoustics, for providing a truly exceptional preamp and phonostage!

Specifications

Gain - Line:
16 dB to balanced outputs
10 dB to unbalanced outputs

Gain - Phono:
Adjustable: 40dB, 50dB (factory setting), or 60dB

Input Impedance - Line:
10 kohm (each phase)

Input Impedance - Phono:
Adjustable--- 50 kohm (factory setting) to 100 ohm

Output Impedance: 300 ohm (each phase)

Volume Control: solid-silver contact stepped attenuator

Inductor-input audio power supply filtering

Ayre Conditioner power line RFI filter

Remote control option

Power Consumption: 20 Watts

Dimensions ((WxDxH in inches):
Main Unit 18 x 12 x 6.25

Power Supply 13 x 8 x 3.75

Weight: 45 pounds

Company Information

Ayre
2300-B Central Avenue
Boulder, CO 80301

Voice: (303) 442-7300 x 233
Fax: 303-442-7301
E-mail: info@cragdesign.com
Website: www.ayre.com