Sanders Sound Systems Magtech Stereo Amplifier



May, 2012

For some reason there remain relatively undiscovered gems in the audio world. The Sanders Sound Systems Magtech amplifier is one of them. Certainly their designer, Roger Sanders, has been around the block several times and mention of the brand name often brings recognition but not familiarity. Someone may have read about Sanders Sound Systems loudspeakers and amplifiers in a show report or magazine but not actually heard them. 

I found the Sanders Magtech amplifier somewhat by accident myself. I was searching for an amplifier for my Quad ESL-2805 loudspeakers and I found the Sanders ESL Mark II amplifier designed specifically to handle the more complex load of electrostatic loudspeakers (ESLs). The Sanders Sound Systems website explains that ESLs are driven by voltage in contrast to magnetic speakers that are driven by current. All this occurs because a magnetic speaker is a resistive and inductive load while ESLs are a capacitive load. Since most amplifiers are designed to drive the more common magnetic speakers, Roger Sanders recognized the need for an amplifier more appropriate for driving both his own and other brands of ESLs.

Hang in there; I will get to the Magtech amplifier shortly. A little more information on the ESL Mark II amplifier is warranted here since it is the foundation on which the Magtech amplifier is designed and built. While they are designed with different loudspeaker demands in mind, neither amplifier is limited in its final application. Roger Sanders has assured me the ESL Mark II amplifier can perform very well on magnetic speakers as well as on ESLs. He further advises that the Magtech amplifier is the best amplifier for either application but the edge over the ESL Mark II amplifier is not as significant on electrostatic loudspeakers. 

To achieve optimum performance Roger has eliminated protective circuitry that causes the harshness frequently associated with solid-state amplifiers. One key to eliminating protective circuitry is the design of an output stage that is so powerful it is never stressed. The ESL Mark II uses twenty large output transistors capable of delivering 7,000 watts (64 volts RMS) into an ESL. The amplifier can drive a 1/3-ohm load. 

But there is more to eliminating protective circuitry than just “Tim the Tool Man Taylor” amounts of power. An amplifier must also be designed to prevent thermal runaway and maintain a stable bias at the appropriate level regardless of power-level demands or constantly varying load demands from loudspeakers at different frequencies. Both the Mark II ESL and Magtech amplifiers use Thermal Trak transistors. Thermal Trak transistors have built in temperature sensors to adjust bias much more quickly than conventional amplifiers. Most conventional solid-state amplifiers have temperature sensors mounted on the heat sinks, which results in inaccurate readings due to the time delay. The result is an unstable and inaccurate bias and the possibility of overheating, which ultimately demands protective circuitry. 

The above features are also incorporated into the Magtech amplifier, which is essentially a Mark II ESL amplifier with the addition of a linear voltage regulator. Line-level electronics typically use voltage regulated power supplies but regulated power supplies would run too hot for the larger power requirements of amplifiers. To solve this problem Roger Sanders has developed (patent pending) a voltage regulator that he claims is essentially 100% efficient. In addition, the regulator does not employ switching that could create radio frequency problems. Roger further claims the regulator maintains a stable voltage regardless of load or reasonable changes in the line voltage. This enables the maintenance of stable bias and unchanged distortion levels. 

After living with the Magtech amplifier for a couple months I spent some more serious time rereading the information on the Sanders Sound System website. A well-written white paper can always sound convincing to me. But what resonated with me as I explored the technical design of the Magtech was how much it confirmed my subjective observations. 

At first blush Magtech amplifiers are not that exciting. Seduction is more their style. One reason the Magtech amplifier does not call attention to itself is that it does not excel in (or exaggerate) any specific area. But rather, it performs equally well at all frequencies and never shows strain. Consistency was what I had written in my listening notes. Performance was uniformly good from top to bottom. The figurative light bulb was burning brightly above my head. Finally, something I read in a white paper could be confirmed by my actual experience.

It is easy to get Quad speakers to sound good. They are legendary for coherence and an engaging midrange. It is more difficult to get them to sound their best throughout their frequency range. I have tried various tube amplifiers on the Quads and found tube amplification provided extremely enjoyable sound but only within certain frequency range limits. The Quads are not as easy a load as one would be lead to believe by how good they sound with tube amplification. The Magtech further revealed the tube shortcomings (which I had already noticed) by expanding the peak performance range of the Quads. The “sweet region” grew to the limits of the speakers themselves. Meaning they suddenly didn’t have extended bass but what they did have was tighter and more refined. The top end was not more extended, just smoother and less brittle. The Magtech amplifier did not create new loudspeakers; it just let them be all that they could be. 

The amplifier also exhibited a rich tonal density with good soundstage depth and imaging. Performers and instruments were not exaggerated in size. Extended harmonic reproduction made piano and stringed instruments more realistic. 

While the Magtech is a solid Class-A/B design it provides more power and is more efficient than most A/B designs. It draws approximately 40 watts at idle and up to 2000 watts at full power. The Magtech does generate heat but significantly less than many other Class-A/B amplifiers. The heat sinks are small but effective. I measured the idle and operating temperature using a thermal probe. Operating temperature varied with how hard the amplifier was working. The outside edge of the heat sinks averaged about 82°F at idle and ranged from 89-95°F while operating when ambient temperature was 66°F. The low surface temperature makes Magtech amplifiers kid and kitty friendly.

Its size and weight (55 pounds) give it serious attitude but it will easily fit on an audio rack and one healthy male can handle it and bask in a prideful testosterone rush of accomplishment. If you want to feel even more manly, Magtech amplifiers are also available in a monoblock version that produce 1600 watts into an 8-ohm load and 2000 watts into a 4-ohm load. Although they have both XLR and RCA inputs, the stereo Magtech operates in single-ended mode while the monoblock version operates in balanced mode. 

I personally found the Magtech amplifier (black faceplate) quite attractive. The entire amplifier has a solid look and feel to it including the thick top and small heat sinks. Fit and finish are excellent. The faceplate was simple but somehow elegant. This is all in keeping with Roger Sanders’ more pragmatic attitude toward design. His intention is to design equipment that brings the best sound in realistically sized and priced packages. I quote Sanders from his website: “I believe in designing and selling products of real value for a reasonable price.” I applaud that attitude. Too many times I have seen equipment that is only available to the 1% with the biggest wallets, listening spaces, and egos. Ego aside, I don’t fit the other two criteria. I very much appreciate the more practical approach.

Sanders further stands behind his products (both amplifiers and loudspeakers) like no other manufacturer I am aware of. Sanders Sound Systems offers a 30-day, in-home, risk-free trial. That includes the unbelievable offer of free round-trip shipping anywhere in the world for any Sanders equipment. If that is not enough craziness, Sanders products also carry a lifetime warranty for the original owner. Sanders Sound System products are manufactured in Conifer, Colorado and sold both directly and through selected dealers. 

Pure Enjoyment on Quad ESL-2805s:
A consummate artist but not performer, Joni Mitchell was uncomfortable on stage but a master in the studio. She applied multiple layers to “The Tea Leaf Prophecy (Lay Down Your Arms)” from Chalk Mark in a Rain Storm [Geffen 24172-2]. Despite its brute strength the Magtech showed its sensitive side by gently reproducing each layer as the whole it was meant to be and capturing the surprisingly long, barely audible fadeout that would be lost on most systems. It also faithfully captured Joni Mitchell’s voice, mostly clear as a bell but sometimes exhibiting a slight tobacco-induced haze. 

The Magtech did an excellent job of revealing the nuances in Emmylou Harris’s voice on “Can You Hear Me Now” from Stumble Into Grace [Nonesuch 79805-2]. Again there were layers to be revealed including backup singing and soft guitars. And again the Magtech seemed particularly adept at revealing layers without losing the connectivity between them. Other amplifiers might etch each layer independently or smear them irretrievably. The Magtech made me enjoy this and other music to a level I had not previously experienced. I heard more, but not because I was trying. I heard more because it was presented so effortlessly and without drama. The seduction I previously alluded to. No One-Trick Pony:The Magtech had so much available power I turned down the output of my Laufer Teknik (formerly Nova Physics Group) Memory Player to protect my Quad ESL 2805 loudspeakers. When I rotated my Apogee Stage loudspeakers into service I increased the output slightly but still maintained it at a reduced level. I found the Magtech amplifier was equally at home on electrostatic and planar-magnetic speakers.

Although Apogee Stage loudspeakers are nominally rated at three ohms they can dip much lower. The Magtech appeared to have no care in the world; easily handing everything I threw at it. I was particularly impressed that at loud levels I could detect no discernable movement of the Apogee’s midrange tweeter ribbon (MRT). Lesser amplifiers can clip and cause the ribbons to dance with reckless abandon. Slight MRT motion is either a sign of imminent amplifier clipping or the speakers are being over-driven. With the Magtech, the MRTs were rock solid at uncomfortably loud levels. Visual confirmation of what I was hearing-no distortion.

The Sanders Sound Systems Magtech amplifier deserves more than just name recognition. It is well worthy of consideration in any system where its power would be appropriate for the loudspeakers in use. But don’t take my word for it. Find out for yourself by taking advantage of the unprecedented 30-day, in-home, risk-free trial offer.

don shaulis

Rated Output Power (RMS): 2X 500W into 8 ohms, 2X 900W into 4 ohms 
Operation: Class A/B
Frequency Response: DC through 100kHz
Signal to Noise Ratio: >110dB
THD: IMD: Input Impedance: 50kohm (both balanced and unbalanced)
Input Connections: operates single-ended via either RCA or XLR 
Gain: 26dB
Input voltage required for full output: 2 Volts
Slew Rate: 500 Volts/microsecond
Damping Factor: > 600 into an 8-ohm load
Binding posts: WBT 0763
Power Consumption: Approximately 40 watts at idle
Dimensions: (WxHxD): 17” x 5.5” x 16”
Weight: 55 pounds
Voltage: User selectable for use worldwide 
Manufactured in: Conifer, Colorado USA

Price: $5,000

12054 Deer Trail Road Conifer, CO 80433 USA
Phone: 303 838 8130 
Fax: 303 838 8130 


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