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Positive Feedback ISSUE 67
as reviewed by Michael Wechsberg
If you remember the distinctive EDGE Amplifiers then you will be interested in the Maker Audio G9 solid-state amplifier. Tom Maker was the founder and one of the original designers for EDGE. He and his partners sold the company in 2008 and signed a non-compete agreement with the acquiring company. In the intervening years he started a speaker company called Maker Audio where he developed a high-end design that can be customized for the user. Recently, the legacy EDGE Electronics went into bankruptcy, and the amplifier designs reverted back to Tom Maker. The Maker Audio G9 is a rework of the EDGEG8 stereo single-chassis amplifier, but with a 20% boost in power and some important updates to enhance the sound and look of the amp. Also, the new amplifier, together with other Maker Audio electronic products, are offered at significantly lower prices compared to similar components for sale under the EDGE name a few years ago. Ain't that sweet? I heard the EDGE amps at shows where they always sounded great, but only stood out for their impressive looks. After spending a few weeks at home with the updated G9 amp, which has more understated looks than its predecessor, I'm happy to say the sound is now more impressive than the looks. Keep reading for the details.
The G9 kicks out 225W per channel into 8 ohms (compared to 175W in its predecessor). The power supply has a 1250 kVA toroidal transformer with 68,000 mf capacitance, and 14.3 amp current capability. There are both single-ended RCA and balanced XLR input connectors on the rear panel, but in the baseline configuration that I reviewed, only the single-ended jacks were active. Balanced operation can be ordered as a $530 option which uses a different hand-wound high-nickel content core transformer. The rear panel also has a sturdy set of output binding posts, the power switch, and a pair of fuses. The amplifier is housed in an attractive stainless steel chassis with laser-cut markings and rounded edges (hate those sharp edges on some amps). The transistor heat sinks are internal with artistic cutouts in the top of the chassis for ventilation. The amplifier weighs a hefty 68 lbs, and comes in at 17.75" wide by 17.5" deep and 6" high. In my opinion, it looks much nicer than the similar EDGE amplifier it replaces. Maker Audio components are all made in the USA.
According to the Maker Audio web site, the original EDGE amplifier design has been updated with some new technology including, "more efficient transformers- 5% better transformer efficiency and 20% better transformer shielding. Also a new filtering power supply is included based on the original EDGE ACF-1 and 2 designs. It is built right into the amplifier and removes any noise and unwanted DC components from the AC line, eliminating the need for external line filters or AC conditioners." I asked Tom Maker to elaborate on some of these changes and he sent me the following information that I thought would be of interest to PFO readers:
"One of the things that sets the G9 apart is the use of our ACF2 line conditioner that is built into the G9 power supply. As you know toroid transformers are very sensitive to DC and noise over the incoming AC line. It only takes a quarter volt or so of DC to saturate the core of the transformer. So we treat the incoming AC line as a balanced input or a differential of the 2 lines, neutral and hot. We first filter any DC component from the line and then we remove any noise coming in through the line with a 2-stage Pi filter. Once the AC has made it through the filter it is into our new transformer. The new transformer uses quad-filar windings and an electrostatic shield as well as complete Mu-metal shielding around the entire toroid, not just the sides of the core. We also have added more capacitance to the filter board as the new transformer is capable of replacing that energy much faster than in the past. The capacitors are also "preformed" by use at the factory before they are assembled. By heating the capacitors for 24 hours, and varying the voltage, we are able to extend the life and lower the break in time period for the capacitors. The output stage has been improved through the use of some new [mil-spec] resistors specifically manufactured for our use in the G9 and NL14 amplifiers. They [are] manufactured from an Alumina ceramic material and incorporate a nickel chrome core and a 0.1% tolerance. This allows the matched output transistors to all work at the same load and output impedance. We also cryo-treat the wire for the output section of the amplifier which realigns the crystalline structure of the wire and makes it a much better current conductor."
I found the power supply updates to be particularly effective. When I first received the amp I plugged it into my system power conditioner, a PS Audio Power Plant Premier. Every amplifier I have had in house over the past five years has benefitted from using this conditioner vs. plugging directly into the wall. However, in the case of the Maker Audio amp, I thought the sound I heard initially was not as fast and dynamic as I expected. So, I brought out a longer power cord and plugged the unit directly into the wall outlet. I was rewarded with much better dynamics and a more forward image presentation. I decided to keep the amplifier connected directly to the wall for the remainder of the review process, and I applaud Maker Audio for including effective power conditioning inside their amp. I should note here that I did recently install a dedicated AC line for my audio system and that may have helped the amp perform well even without a separate line conditioner. As I have written in other reviews, the quality of the AC power in our households is inconsistent, so all audiophiles who care about sound need to experiment with power conditioning and cords to find the best solution for their systems.
Also worth mentioning is that Maker uses all NPN-type bipolar transistors in the output stage instead of complementary NPN and PNP types as in most type-AB power amps. Tom Maker contends that it is almost impossible for N-channel and P-channel devices to perform the same way over their operating range because they are manufactured and doped differently. By using all N-channel devices in the output stage that are prescreened and matched by hand to within 1% for current gain, Maker believes he gets the best power handling and lowest crossover distortion. The same meticulous care is used for the input differential pair of transistors as well.
This is my first review for PFO in several months due to the time it took to make some big changes in my audio world. First, I moved to a new city and house, and my listening room went from a moderate-sized dedicated listening room to a much larger multi-purpose room. Second, I swapped speakers from the Marten Miles II to the larger and newer Marten Django XLs. Bob Levi reviewed the Djangos for PFO a few months ago. My E.A.R. electronics and CD player remained the same as did my Townshend Rock 7 turntable with the London Reference cartridge. However, it has taken quite a while to find the right location for the new speakers, break them in, and re-calibrate my ears to how things sound in this new environment. I have to admit to you that I'm still scooting things around and trying various tweaks, but I thought I was far enough along to give the Maker Audio amp a try.
As I mentioned earlier, I inserted the G9 into my reference system in place of the E.A.R. 890 tube amp (70W per channel). I plugged the G9 directly into my dedicated AC line outlet using a 12-foot XLO Signature 3 power cord in place of the Kubala-Sosna Emotion cord that I normally use (it was too short to make it to the outlet). Since only the single-ended RCA inputs were active on the G9, I used a pair of XLO Signature 3 interconnects between the amp and my E.A.R. 868 preamp. This was in place of the balanced Kubala-Sosna Elation interconnects I normally use. Other cabling in the system was all Kubala-Sosna. Later in the review process I set up a smaller scale system using the stand-mounted Fritz REV 7 speakers from Fritz Speakers (review in process) and using a pair of Harmonic Technology Pro9 Reference speaker cables between the amp and speakers.
The first thing I noticed about the G9 was its tuneful and tight bass response. It did a masterful job of controlling the six woofers in my Django XL speakers, providing all the extension and clarity these excellent speakers are capable of. This provided a solid foundation for all the music I played through this amp. The firmness and control extended through the upper bass and lower midrange giving the music natural drive and rhythm. I found the midrange to be very neutral on voices, strings, horns, and other instruments. Good piano recordings sounded like good pianos. Male voices came across with power and nuance, while female voices sounded balanced and tender when needed. Lyrics were notably easy to follow revealing a neutral frequency balance and low distortion, even at low signal levels. I can understand why some reviewers referred to the predecessor EDGE amplifiers as "sweet" as that is a good way to describe how this amp portrayed the upper midrange and highs. It has none of the thinness, glare, or grain of some other solid-state amps, nor the syrupy fullness of some tube amps, i.e. not too hot not too cold, but just right. Highs were extended and clear without sounding harsh, even on some overripe material. Although I fronted the amp with a tube preamp, I feel it would be compatible with decent solid-state preamps or line stages as well. I already mentioned the outstanding dynamics this amplifier had in the low end, but this performance extended also into the midrange, giving the music exceptional forward drive. The G9 has plenty of power and remains clean sounding even at high volume levels. Microdynamics were also excellent over most of the frequency range.
The G9 amp is also a soundstaging champ. It provided a wide soundstage with nuanced depth, if the recording allows, and images are distinct and stable. I found the presentation a bit more forward than I am used to with my reference electronics, but this could be due to the different cables I was forced to use with the G9. I did not do too much cable swapping with the G9, but it certainly had sufficient resolution to differentiate between alternative cable types. If you try out the Maker Audio G9, I believe you will be rewarded if you make the effort to find the right combination of cables to use with your other equipment.
The G9 really came into its own when I inserted it into the small-scale system fronted by the Fritz REV7 speakers. These speakers, with just a single 7-inch woofer, don't go as low as the Django XLs, and are better suited to smaller rooms than the one I am using, but with the G9 amp they delivered great bass and an exciting sonic experience. The rhythmic drive was terrific, and it was hard to sit still while listening to multiple CDs. The neutral balance of the amplifier complemented the speakers well.
I really have to nitpick to find something to complain about in this amplifier, but that's part of my job as a reviewer. The shortcomings of the G9 are all at the edges of the performance envelope. Maybe the definition and clarity are not as good at the edges of the sound stage as in the middle. The extreme high end (as high as I can hear anyway) is not as transparent, delicate, and airy as I hear with my reference amplifier. While small-scale music, like jazz combos, come across really well, in larger scale works it is a bit harder to pick out individual instruments playing in space. I also did not get as good a sense of hall sound as I hear on some more expensive amplifiers.
EDGE Electronics, and now Maker Audio, are known for the innovative use of what they call "laser biasing" in their top of the line amplifiers. This was not implemented in the amplifier I reviewed, but is available for the G9 as a $680 option, it is standard on their other power amp, the NL14 at a cost of $9875. Again according to Tom Maker what they do is saw off the top of the can for the transistor that drives the output stage and insert a 730 nm laser diode with the output of the laser shining directly into the silicon transistor junction. The laser output tracks the DC rail voltage and effects the operation of the driver transistor in a positive way, giving the sound extra "air" among other things. Maker says the company put together a blind listening test last summer with 10 listeners who were able to switch the laser biasing circuit in and out without knowing which position was which. Eight out of 10 listeners consistently preferred the sound with the circuit in the "in" position. Not definitive but promising. It could be that the laser biasing scheme enhances the amplifier in just the areas where it has weaknesses and turns the G9 into a real sonic champ at an attractive price. I have asked Maker Audio for a second sample of the G9 with laser biasing, and if they come through I will write up a follow-up review.
I never heard the EDGE G8 amplifier that is the basis for the design of the Maker Audio G9, however, the newer amp has 50W/ch more power, a bigger and better power supply, better parts, and a nicer package, yet it costs over $3000 less. Wow! Even more important the G9 is an outstanding sounding amp that is powerful enough to drive all but the most inefficient speakers, and provides a driving and exciting sound that is neither too dry nor too syrupy, but right down the middle. It does everything well and has very few shortcomings. The price range between $2500 and $7500 contains many fine amplifiers, both solid-state and tube, and it is difficult to place the G9 in context in this range. All I can say is that I really enjoyed my time with the G9 and believe it would do a great job with many speakers. I strongly recommend you contact Maker Audio for a dealer in your area to try it out for yourself. Michael Wechsberg
Maker Audio G9 Amplifier