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Amplifiers for Non-Bass InstrumentsCombo Amps

** Acoustic Image CORUS Series 4plus Combo Amplifier - LAST ONE!

         Manufactured by: Acoustic Image

Continental US - larger items may carry a partial shipping charge to AK, HI and PR

This Item SHIPS FOR FREE in the USA!
(Note that larger items may carry a partial shipping charge to AK, HI and PR.)
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FLAT RATE WORLDWIDE SHIPPING!14 Day Trial Period on Series 4 Acoustic Image amps and speaker cabinets

New owners have a fourteen day trial period during which they may return the amp in new condition -- NO QUESTIONS ASKED! -- for a full refund, minus our outgoing shipping cost and a small transaction fee to cover credit card or PayPal payment processing. Returns must be preauthorized; a restocking fee applies if the unit is not returned in new condition.

The Corus combo (and its matching extension cab) are a specially modified version of Acoustic Image's well-loved Coda combo amps. What's different? While the Coda (and its bigger brother, the Ten2) are truly full-range amps, with the bottom end to be excellent for low-pitched instruments like upright bass and acoustic bass guitar, the speaker array in the Corus combo is "voiced" for higher pitched instruments. Its output has a more "forward" sound, which makes it an excellent choice for instruments like acoustic and "jazz-box" guitar, violin, mandolin, cello, and more. It even works wonderfully with keyboards - check out this review of the Series III Corus (Dec 2008) from Keyboard Magazine!

How is this "more forward" sound accomplished? The difference is the special design woofer, which replaces the standard subwoofer-style speaker in the Coda. The Corus woofer is more efficient, and the crossover network is modified for a different balance between the woofer and the midrange/highrange front panel speaker (which remains the same as the one in the Coda). The Corus, thanks to the increased efficiency (more volume per watt) sounds louder than the Coda at a given level setting and its character sounds a bit more "in your face." The trade-off to the improvement in efficiency - there's always a compromise! - is slightly less bass response.

The Corus is designed to better match the needs for guitar and other instruments that occupy the sonic space above basses. Many keyboard/piano/organ players have found that they prefer the voice of the Corus to the Coda as well, despite the extended range of most keyboards. Frequency response: 60-16kHz (+/- 3 dB) versus 40-16kHz for the Coda, and Efficiency: 93 dB/m versus 90 dB/m for the Coda.

The Corus S4+ combo incorporates a 650W Clarus 2-channel head, mounted into the cabinet using the Cabrio Docking System, which allows you to separate the head from the cabinet for independent use.

A cool built-in "kickstand" mechanism allows the cabinet to be tilted to better direct sound to the player’s listening position. For larger venues, the Ten2 EX (Series 4) extension cabinet is an ideal match.

LOTS more detail below!

Bob's first Acoustic Image combo (a Contra) arrived in 1999, and we've been hooked on their incredible amps ever since. Its design was innovative, it was eminently portable, and its sound was unmatched by any other amp on the market. And the smart folks at Acoustic Image didn't rest on their laurels, they continued to hone the design by responding to the needs of their users; over the years, they made them lighter, smaller, and more powerful. Not to mention better-sounding, quieter, and more feature-packed.

They've come a long way since the first series of amps, and we're very proud to have made the journey along with them -- as a valued "partner" (not just a "seller") for Acoustic Image.

So now, we have the next generation of amps. With the advent of the new "Flex" system (see related links, below), Rick Jones -- the bassist and engineer behind the design of these fabulous amps -- seized the opportunity to improve on the design of the Acoustic Image preamps. As of now, all of the two-channel Acoustic Image models -- Ten2, Coda, Corus, and Clarus -- incorporate the new "Flex" design preamp, which features a new four-band EQ, improved effects, and more (see below.) These new models are therefore designated as "Series 4PLUS."

The Corus amplifier is an all-in-one "combo" amp, meaning that it contains a preamplifier, power amplifier, and speaker system in one compact unit. We've broken down our description below into sections so that you can understand the various parts of the whole.

The Preamp:

A key ingredient in Acoustic Image gear is the very careful design of the electronics. They have always been engineered to deliver the natural sound of your instrument, no artificial flavorings or colors. Please answer this question... do you want to hear your instrument or the amp??

Me, too. My specifications for an ideal sound is for a pickup/mic and amp to simply make my bass sound bigger.

Besides the amazing transparent sound, useful features have been designed into the Acoustic Image preamps to provide the most flexibility for various playing situations. For instance, you get -- on each channel -- a parallel effects loop, and a selectable low-cut (aka high pass) filter to help with feedback or “boominess” elimination (see explanation in features list below). Both channels have on/off access to the built-in digital effects. You also get a balanced direct out with ground lift, as well as pre/post setting, to allow connection to a mixing board for PA support, or for recording purposes. There's even a Phase Switch, which alters the phase by 180°, which can often help with acoustic feedback.

The front end also features the input options for either microphones (XLR) or instruments (¼"), and switchable 48v phantom power -- and a 10db gain switch (for low/high output mics) -- is available on the XLR input. Separate Input Level (gain) and Output Volume Controls allow for precise tonal vs. volume control, and a Master Mute Switch allows you to cut the output for silent tuning or for breaks.

The two-channel, Series 4PLUS Corus has two separate channels which can be used to blend two sources - two different pickups or mics (or a combination of the two), or two different instruments. The XLR and ¼" inputs are on separate jacks. Additionally, they are separately buffered, which means that you could effectively use both at once, on each channel. You would only have independent control if at least one of those sources had its own volume control (like a keyboard, or an instrument with an outboard active preamp) but it does open up the possibility of actually "mixing" up to four different sources.

The preamp features a new four-channel equalizer, as follows:
  • Low: Shelving, ±12dB at 50Hz
  • Lo Mid: ±12dB at 250 Hz
  • Hi Mid: ±12dB at 1200 Hz
  • Treble: Shelving, ±12dB at 8 kHz
The built-in Digital Effects can be assigned to either channel (or both/neither), and the amount of the effects in your mixed signal can be adjusted with the level knob. The rate setting is now configurable (!) and the effects include the following presets:
  • Reverb
  • Delay
  • Reverb PLUS Delay
One last new feature - illuminated on/off buttons for the front panel controls to indicate whether the button is on (lit) or off (unlit). This is really helpful on a dark stage!

The Power Amplifier:

More Power!! (please insert your own Tim Allen Home Improvement TV show grunts) Yes, it can put out up to 650 watts (at 4 ohms). That said, the combos are not rock and roll amps — a small combo shouldn't be expected to compete with your 4x12 Marshall half-stack! And it doesn't sound like a Fender Twin.

With that sort of power, this combo can get quite loud. But the wattage is there to ensure smooth, clean response. The somewhat percussive nature of stringed instruments can be very demanding. The "extra" energy (commonly called "headroom") is available to cleanly handle those peaks and percussive plucks and heavy strums, so you don't get that "squashed" sort of attack many amps often deliver when they run out of gas.

The wattage is certainly handy to have when you have larger gigs, too. Lots of players gig Acoustic Image Clarus heads (which is identical to the preamp/power amp section of this combo) along with a more conventional and larger speaker cabinet for bigger venues. And since the head "pops out" easily and quickly -- 30 seconds or less, no tools required -- you have that option available to you with this combo! I, myself, have taken the head out of my Coda combo, for use with a larger speaker setup, on electric bass/classic rock gigs. It did an admirable job driving a pair of Euphonic Audio Wizzy 10 cabs -- it makes for a formidible, yet still very light and highly portable, rig.

The Speakers:

The design and performance of the Acoustic Image speaker array is quite revolutionary. The lowest bass frequencies are omnidirectional. As we all know, our acoustic instruments do not radiate only in one direction — their sound moves about the room. The ten inch down-firing woofer in the Acoustic Image combos spreads that sound around naturally, as our ears might expect. There is still plenty of definition, it's just not as annoyingly directional as so many other amps can be. With other amps, you might walk across the front of the stage, and suddenly you walk into a small "zone" where THE guitarist's amp is SHOUTING at you. Not with this amp.

But that's only one of the differences between it and other bass amps. These combos have a complement of drivers that results in a full range speaker cabinet. In addition to the woofer, you'll find a five inch cone mid/high driver. Plug your MP3 player in and be amazed at the result! Nice tight bass response, with balanced mids and highs; real, uncolored sound. As pure and clear as the sound in front of your instrument, no added "shading."

What you get is flat frequency response across the spectrum, extended, tight, well-controlled natural bass sound, and omnidirectional output of the lows (so you can be heard, without monitors, all over the bandstand) — all in a package that's about foot tall and less than 23 pounds in weight! In fact, the amp virtually disappears on stage leaving behind the natural sound of your instrument - it's as if your instrument got a lot bigger and makes more acoustic sound!

About the 2-way cabinet (didn't AI Combos used to have a tweeter?)
Note: in late 2010, the Acoustic Image combos and speaker cabinets evolved from a three-way (Woofer + Midrange + Tweeter) speaker array to a two-way (Woofer + Mid/High Driver) arrangement. The original tweeter was crossed-over at such a high frequency that some folks couldn't even hear the difference when it was on or off! The new arrangement actually has several benefits:
  • The new proprietary extended range driver, exclusive to Acoustic Image, is smoother and more detailed than the previously used midrange and tweeter combination
  • Using fewer speakers to cover the full frequency range reduces phasing and amplitude anomalies caused by crossovers in multi-speaker systems (translation: all things being equal, two-way systems are better than three-way)
  • The new 5" driver has higher power handling, providing a bit more perceived volume and definition when needed
Is the Clarus the Ultimate Back-up Amplifier???
(The removable head in this combo amp is exactly the same, feature-wise, as the Clarus)

These days I actually gig electric bass more than upright (hey, the market dictates what pays, not taste, and I'm sure we both could name some artists that evidence that fact!), and I've been enjoying gigging with the Random Act of Blues this summer of 2011. Anyway, I was auditioning a new bass head that I didn't completely trust, so rather than lug my heavy rack case on this particularly hot day, I stuck a Clarus in one of our Gollihur Gig Bags just in case.

As it turned out, the guitarist's Marshall head died after the first song! I grabbed the Clarus as a temporary replacement; ok, it wasn't a Marshall but he plugged his pedalboard output into it, and it got him through the rest of the set. Thanks to this experience, it occurred to me that the Clarus may be the perfect "backup" amp! Think about it:
  • It is very compact and less than 5 lbs. -- so it's hardly any trouble to carry
  • It has plenty of power to cover bass guitar or URB requirements
  • The Clarus has effects on-board for guitar
  • The 2-channel model has two separate channels with EQ, so along with reverb or delay, so it can act a little PA or keyboard head
  • With its high-pass filter and EQ controls, it can make a solid stage monitor amp
How cool is that?!?

  • Cabrio Docking System allows you to separate the amp and speaker components for separate use!
  • 1/4" or XLR input; input impedances are 1 megohm or 600 ohms based on jack chosen, separately buffered
  • Effects Loops via 1/4" phone jacks for each channel
  • Phantom power (switchable) on XLR inputs
  • Channel Input and master level controls
  • Balanced XLR Line Output with Ground Lift
  • PRE- or POST- switch for XLR output
  • Mute switch
  • Headphone output
  • AC Power On/Off switch with LED Indicator
  • 650-Watt (@4 ohms) "Digital" Power Amplifier -- clean power! (Internal speakers are 8 ohms)
  • External Speaker Output (Neutrik Speakon)
  • Two-way Sealed Speaker System
    • 10" Long-throw Low-frequency Woofer
    • 5" Mid/High-frequency Driver
  • Detachable AC Input Connector with Built-in Fuse
  • Dual voltage operation (115v/230v, 50/60 Hz) via automatic switch (comes with USA Cable; to use in other countries, you can source an IEC-C13 AC Cable, also commonly used for computer power supplies.)

  • Molded polymer results in a stiff but light enclosure
  • Lightweight- less than 23 lbs! with Durable Molded Enclosure
  • 12" H x 15" W x 13" D
  • Molded Carry Handles
  • Fitted slip cover with cable pocket and shoulder strap included

Includes Vinyl Cover

Included with all of the combo and extension speaker (EX) models is a lightweight "dust cover" with shoulder strap and accessory pocket. Made of lightweight vinyl, it covers the top and sides of the cabinet, with openings to allow access to the amplifier's integrated handles. It also comes with a carry strap which loops through the openings and the amp handles, allowing you to "shoulder" the amp. The cover is handy - it even has a small pocket for cables, tuners, and other small gigging accessories. But don't expect it to substitute for a case, as it offers only minimal "protection" from slight bumps and other minor hazards.

The photo at left shows it with the cover on and carry strap ready for transporting. A zippered pouch is provided to carry the power cable and other small items, shown in the photo to the right (without the carry strap). This light-duty cover will not shield the unit from rain, and it does not cover the bottom of the cabinet.
Not 100% Sure? New owners have a fourteen-day trial period during which they may return the amp, in like new condition, for a full refund less actual shipping cost.

This item is made in USA! Click for more 'Made in America' items!

Is this product returnable? Click here for our return policy.
Is there a Factory Warranty? Click here to find Warranty Information for all of our manufacturers.
International customer? Click here for important information about ordering from outside the USA, and what to expect concerning taxes, VAT, delivery times, and more.

Check Out the FAQ Resources That Apply to This Product:
   ACOUSTIC IMAGE COMBOS/SPEAKERS: What's the difference between the Contra, Coda, Corus and TEN²?

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Some of our customers have told us what they think about this product.
Check out what they had to say!
I've had the AI Corus for about 2 weeks now, with probably 4~5 different gigs, and I have to say I am pretty impressed with it. It just sounds like my guitar, nothing else. I don't hear the amp at all! It's just my guitar louder.

I've tested a microphone, piezo, a magnetic pickup. Ran a violin through it, and vocals too... even a bass... it seems to always work no matter what I do. I didn't even spend any time fiddling with the settings yet.

Also I got rid of my (outboard) preamp. The levels are good enough to catch whatever volume my guitar produces. Thanks for your help and your advice! I've already recommended Gollihur to other friends, some who already called you.


I received (the Mooradian bag) yesterday... Like the amp, it looks tough built. I enjoy that. Thanks again for your help, you and Gollihur Music are fantastic. I will mention your services everytime I get the chance.
Stephan C (May 2012)
I just wanted to thank you guys - I just got my new Acoustic Image Corus, and it's just phenomenal. Light, easy to carry, and I'm very very pleased with it. I just wanted to let you know that I appreciate your help, always, and I hope to talk to you soon. Thanks again, and I wish you well.
Ramon Z. (April 2016)
Hi Mark I'm loving the new amp! Thanks for going beyond just answering my questions and actually taking a minute to relate some of your experience. That, plus the speed of the free shipping is some of the best service I've experienced. I will definitely be recommending you to whoever I know that's in the market for new gear. Thanks again!
James C. (October 2018)