Review: Green Mountain Audio Callisto Monitor

Category: Speakers

I love Green Mountain Audio speakers!!!

Okay, let me back-track for a minute. I stumbled upon GMA by chance. Visiting's Discussion area was a regular thing for me. You see, I was in the market for a higher-quality, audiophile speaker- a step up from the, now discontinued, Sound Dynamics RTS-3s that I'd been using for a few years. I'd just switched over to tube amps, and wanted to experience as much of the tube resolution and texture as possible. With a budget of $2500, I kept my eyes peeled for the future "star" of my system The Discussion area was full of supporters for the various brands of loudspeaker out there, but none seemed more vehement in their devotion than those to the Europa, Roy Johnson (the designer), and Green Mountain Audio. After much research on the Europa, I decided to get a pair, but this plan was soon derailed in favor of a new destination. There was talk of a "Europa II" in the works for awhile, but this model was put on hold in favor of an entirely new design, which came to be known as "Callisto".

What makes someone buy a product sight unseen, and unheard? Some Green Mountain Audio customers had before, and quite a few had orders in for the Callisto before a photo was up on the net, let alone samples in a showroom. Even with all the hoopla over the Europa's performance, and talk of great customer service, I still had a few reservations. One day, on the way home from work, I called GMA to get more in-depth info on the Callisto. I expected to be put in contact with a rep, but ended up talking to Janet (the company's new "Head Honcho" and a most gracious liaison of hospitality) and Roy himself- both great people! By the time it was over, we had Q & A'ed for nearly two and-a-half hours! Keep in mind this was at the end of their workday; customer service indeed! With an introductory price much lower than it's retail, I made my move.

After finally getting the Callistos home, I set them up downstairs for the 200-hour "break-in". Roy suggest that his speakers be played at moderate levels with a variety of music genres during this time period. I had them wired "out-of-phase" on 24" stands, facing each other, under a comforter. Mid-way through, I got hints as to what pleasures were to come from Callisto. You know how you can instantly tell when voices coming from another room are live or not? The Callisto will make that distinction much more difficult to discern. There were times when sounds coming from downstairs would make me come take a listen. Yeah, they're under a blanket and wired wrong, but still... you KNOW when you're in the presence of a great component, and the Callisto's were whetting my audiophile "appetite" something fierce! Before the end of the 200 hour "warm-up" though, I encountered a few bumps. After all was said and done, I had a new integrated amp (tube, of course), speaker wires, and interconnects.

From what I could tell, speed was the name of the game; transient reproduction and accurate timbres. Roy designs his loudspeakers for a time and phase-coherent sound, which will, as a welcomed byproduct, bring you focus, detail, and texture reproduction a-plenty. I chose the new components in my system based on that mantra, and by the time all were properly broken in to my satisfaction, I had near a eight hundred hours on the Callistos. Finally, with upstream components much more suitable, I sat down for some serious listening.

Let me digress for a moment. I was always into music and audio equipment. I had a stereo, but could never afford the really good stuff. Visiting the local hi-fi shops were my fix. They also served as tangible proof there was better to be had out there. I had no problem hanging out there for several hours listening- until it was time to leave. Fast forward to today's audio climate, and you see companies actually offering exceptional "Bang-For-Buck" products; Green Mountain Audio is at the top of that list. I've seen quotes where the reviewer says to pretend GMA's top-of-the-line Continuum 3 is $30,000, to better describe it's performance level. I'd guess that number should be, at the very least, twice that, because to my ears, the Callisto's overall audio quality surpasses the performance a lot of $10,000 speakers provide.

Back to the question at hand: how do they sound? WOW!!!

This speaker will make you pull out your LP/CD collection and listen to them all over again to get a fresh perspective on how they really sound. A major part in this equation is Roy's ingenuous incorporation of the tilt feature for "Soundfield Convergence". It's great to be able to "dial-in" the sound-stage for a detailed, open view into the music... and what a view it is! First off, definition in the lower octaves is an unexpected plus to world-class speakers the uninitiated might not expect. Most general purpose, consumer-level speakers I've heard merely provide "bump" in the bass region. Kinda reassuring you there's a woofer below. Once you've experienced a monitor that allows you to hear whether a particular synth is a Moog or a Pro One, and the bass guitar is Fender, not Rickenbacker, you can't go back. The AMOUNT of bass you get in the Callisto is also shocking. I've played hip-hop and electronic tracks with plenty of slam, and the Callisto reproduces it down to it's lower limits, loud and clear. As you can probably tell, the Callisto is not afraid of power. This speaker will go LOUD, from the top, all the way down 'til the mid/woofer bottoms out- which will require very low notes to force the issue. The tweeter just continues to soar; you'll probably fry the capacitors before this thing dies. Speaking of the other half, the midrange and treble of the Callisto is MADE FOR TUBES! One reason I chose this monitor over the Magnepan 1.6QR, was The Callisto's propensity for "wrap-around" sound. The Maggie, in contrast, has a "straight-shot" way of launching sound from it's panels. All you get is what's coming at you in front, and reflected sound from behind- like a figure-8 pattern on a microphone. The Callisto is closer to an omni mic presentation. The sound erupts out of the marble enclosure, down the walls, and over your head to engulf you. This is an excellent way to show off recordings with great ambience, like the Mapleshade stuff for example. These traits are realistically communicated by an excellent solid-state amplifier, or better still IMHO, a good tube amp, which is facilitated by the 90db rating.

The upper octaves allow you to hear just how good (or bad) the other components in the chain are. I recently upgraded my CD playback to the APL/Pioneer 563a universal player. SACD, DVD-Audio, and high-rez DVD video soundtracks are now added to the gauntlet this little GMA will go through. And guess what else? 500 more hours of break-in, but- and this is important- I got to hear the progress the player made throughout, thanks to the Callisto's extraordinary resolution. When the APL was thoroughly run in, I discovered i needed to fine-tune my speaker setup a little more. The APL is much, much more focused than my previous disc player, thanks to it's ultra-low jitter spec. This provided for a match made in heaven! For the first time, I can now hear a very distinct sense of depth in recordings. I have the Kimber Kable SACD "Iso-Mike" that is a test disc with several audio snippets to help diagnose your system. The track, "Choir Roll-call" is basically the choir announcing their names, one by one. The sense of space on this recording is ridiculous! Another track, "Janitor" actually has a guy walking around my stereo setup, giving a much better impression of "space" that the "Professor Johnson..." track on the XLO/Reference Recordings Test & Burn-In CD didn't. The more I listen to recordings such as these, the more I love these speakers. The Callisto seems to thrive on source and amp components that dare it to reproduce what they send; a "stare-down" of sorts. That damn Callisto hasn't blinked yet! I now have over 2000+ hours on these Green Mountain Audio gems, and they continue to impress me. The only way they leave me is if I get enough loot to upgrade... to another GMA product, that is (I can only imagine what the Continuum 3 would sound like with such a synergistic setup).

Roy is right on the money by making phase and time-alignment a top priority in his product designs. Now, whenever I listen to other speakers, I immediately hear what's missing. A full frequency response can't cover it up. Avant-garde styling won't draw my attention away from it. Plain and simple, if the music doesn't arrive at your ears the way live sound does, you're being short-changed.

In closing, I'll finish this like I started: I love Green Mountain Audio speakers!!!

Associated gear
Technics SL-1210 M5GSE (modified)
Cartridge Man Music Maker 3 Cartridge
KAB/Ortofon Pro S-40 Cartridge
EAR-Yoshino 834P (Modified)
APL/Pioneer DV-563A (modified)
Response Audio/Jolida REF-3205 (modified)
Verastarr Silver Reference Signature IC & Silver Signature speaker Speaker cable

Similar products
Magnepan 1.6QR, Gallo Reference
Great review and right on the mark. Everyone I know who owns the Callisto's, including myself, will never go back. "I love Green Mountain Audio". I only have one warning: Be prepared to upgrade every component in your system!!! The Callisto's make you strive for the best. The sound is so incredible and I have gone through every cd I own and purchased more. Thank you Roy Johnson and Janet!
Nice job on the review and the patience you have shown by not posting your thoughts until the 2000 hour mark! Mine have around 60 hours of break in and I'm honestly impressed with each listen. Perhaps the one point I relate to the most in your review is the soundstage... I sit in front of my system and I literally cannot tell the sound is comming from my speakers, it seem to be as wide as my room. I want everyone to hear what I am hearing, these truly are special.

I echo your comments about Roy and his team, they are super to deal with, I too have had lengthy discussions with Roy, this guy is the real deal in this business.
Thank you both for your kind words. This is my first review, and I tried my best to convey my feelings on this great product.


I've already given myself over to the notion that I'll be upgrading parts of my system. The only problem right now is moolah :) I must say what I have right now sounds very good, and when I do upggrade, I'll be sticking with the same brands.


If my system had come together as soon as I wanted it to, i would have commented at around the 600-800 hour mark.


As to the Callisto break-in period, I made two mono CD-Rs of varying styles, but I made sure at least 60% of each disc had robust bass information. I wanted to make sure thee woofer was well broken in. The tweeter would take care of itself in time, but I also made sure to include songs with heavy piano use, as well as those with horn, percussion, and great cymbal workouts.
Very nice review. One of the few reviews that someone waited a long period of time to make sure the break in is done. Too many times people give gushing reviews on a new product and then realize a few months later it wasn't so great! Bravo!

I love my Europas and hope to one day upgrade to the Callistos.
I am going to give these a listen when I get a little extra cash on hand (new business stuff going on). I just moved to CO and sent GMA an email and Roy replied right away. There is a guy that is pretty local here and I'm going to truck it to his house and give them a listen. They sure sound like they have a great product and I'm pretty itchin to get out of the home theater stuff and back into two-channel (although not as bad as when I decided to get rid of my music stuff and bought a Sony HT reciever and Bose AM-10's. Now that system stunk).

Great review!

(Tom Petty singing... "The waiting is the hard est part" :)

This is the first review I've written, for a goood reason. I've had feelings about products/music before, and changed my opinion of them later. Aside from giving equipment a good burn-in, time allows you to settle on what you actually feel about them.


I'll tell you now, you will grow to love them!!! One other thing: you may eventually go back to HT and surround, BUT it will cost you, 'cause you'll want every speaker to be a GMA -and need high-resolution components to drive them.
I'm curious to know if any GMA enthusiasts listen to much classical music. The Europa, which is the only GMA speaker I have heard, does very well with rock, but I'm less sure of its ability to do the "refined" thing, which I find is very important when I listen to classical.

I should have went more into detail on the music I listened to while reviewing these sppeakers. I have classical Cds, purchased some of the Mercury SACDs, and have been picking up vintage classical LPs of excellent sound quality. The GMA's being time/phase-coherent, aren't romantic-sounding; they provide the truth. If your classical doesn't sound good in the first place, these won't help it. That said, thay do classical music justice.

Dooes your Lexicon have a "Direct" or "Bypass" mode? Get an external phono preamp for those inputs.
Nope. All digital DC-2. Makes the old Systemdek sound pretty brutal. I just need to buy a new kit since I'm getting a bit tired of the HT thing. I do plan to visit the GM factory soon. They sound like a great bunch of folks.