Sign in to follow this  
Followers 0
Alex 54

Ovation Model 1721 Power Amplifier

1 post in this topic

Super Wammer

Untitled-1.jpg.0fc1c72a5af3ae8a5ebc9da6f386b32c.jpg

 

Ovation 1721 Power Amplifier

By Alex Colburn

 

Introduction:

Ovation High Fidelity are a relatively new UK based designer and manufacturer of hand built audio products pitched towards the higher end of the market who sell directly to the end user. I was asked to review their most recently released flagship product, the Model 1721 power amplifier. The amplifier arrived in a substantial tri-walled carton packed with custom expanded polyurethane foam. Some care is required during the unpacking process as the unit weighs in at a substantial 24kg. Also in the case was a 2m IEC power cord with suitable mains plug, user manual, Ovation High Fidelity brochure, customer service contact sheet and test report with the final test measured parameters for the amplifier (which in this case generously exceeded the manufacturers published specifications).

The 1721 case is of predominantly silver appearance and of conventional design with black anodised vertical cooling fins running the full length of both sides and black anodised rear panel. Internal ventilation is achieved through a custom machined top plate with individual vents covered with stainless steel mesh. Overall, the case gives the general impression of high quality sturdy construction with extensive use of stainless steel cap-head screws. Four 40mm diameter polished stainless feet support the case some 15mm clear of any surface it is placed on. Ovation state the amplifier should not be operated on a carpet or where air circulation to ventilation slits in the baseplate of the case will be restricted as this will lead to overheating. External dimensions of the case are 450mm wide x 450mm deep x 130mm high (excluding the feet). It is refreshing to report on a product where the manufacturer has chosen not spend an unreasonably large proportion of the manufacturing costs on an “Arty” case to house the most important bits (the capital A is intentional).

The front panel is a simple natural brushed aluminium affair with black push-button power switch and red/green coloured LED whose colour and flash state indicates which mode the amplifier is in. At the centre of the rear panel sits the IEC mains connector, strategically positioned to minimise wiring between the socket and the main transformer. On the far left of the rear panel two RCA sockets allow connection of unbalanced inputs and alongside two XLR sockets cater for balanced inputs. A small push button switch mounted between the two pairs of sockets is used to select balanced or unbalanced input operation. Speaker connections on the right side of the panel consists of 4 gold-plated heavy-duty CMT binding posts that will accept 4mm plugs, large spades or generously proportioned bare wires. A standard 3.5mm jack 12V trigger input is available for remote control of the amplifier from a preamp or other ancillary equipment.

 

Untitled-2.jpg.b7972a4614658f4ce151548e347c124c.jpg

 

Technical specifications:

The RMS output power is specified as 250W into 8Ω or 480W into 4Ω with less than 0.003% distortion at full power and all frequencies. This particular example could push out 288W into 8Ω at 0.002% distortion. Frequency response is quoted as 20Hz to 20kHz 0dB to +0.1dB or 2Hz to 250kHz +0dB to -3dB, signal to noise ratio better than -100dB referenced to 1V output or -120dB referenced to full output power. Input sensitivity for rated output is 1V for unbalanced and 0.5V for balanced inputs. At 36.6dB into 10kΩ, the overall gain is somewhat higher than the more usual 26dB quoted for many power amplifiers so should be easy to drive but be careful with that volume control!

The beating heart of the amplifier is a high quality 1200W toroidal transformer custom wound with an inter-winding screen to minimise mains noise injection. Throughout the review period, I could detect no significant hum or other mechanical noise from the amplifier during operation. Cooling of the amplifier is entirely convective so there are no pesky fans to power up during your favourite quiet passage. Although the 1721 is capable of delivering powers in excess of 1kW, this class AB design consumes just 100W under idling conditions. At normal listening levels, I found the casing runs at a temperature of approximately 42°C when mounted in my Apollo open frame rack unit.

For those who may be interested in the technicalities, the amplifier topology is built around a fully symmetrical current feedback gain stage with a “Locanthi T” (triple emitter follower) output stage having the properties of low overall feedback, wide bandwidth, high slew rate (250V/μS) and low distortion. In the case of the 1721, this has a paralleled output stage featuring 12 matched transistors for each channel and capable of delivering instantaneous currents in excess of 60A into the loudspeaker load.

A comprehensive microprocessor controlled loudspeaker protection system monitors the amplifier for DC offsets, output overcurrent and over-temperature, disconnecting the output within 100μS. Ovation has achieved this by using a solid state rather than the usual electromechanical relay, which is much slower. If the condition that initiated the trip clears of it’s own accord, the amplifier will automatically re-connect to the speakers and continue normal operation.

 

Untitled-3.jpg.cd3a71de433532b8595516cd2d9ef7c3.jpg

 

Audition:

To take best advantage of the fully balanced topology of the amplifier, Ovation recommend using the balanced input so I decided to drive the unit using the balanced transformer output from my Linn Klimax DSM Mk3. Ovation also recommend a 5 to 10 hour burn-in period for their amplifiers so I ran it continuously for four days to be on the safe side before any serious listening tests.

From casual listening during the burn-in period, I already knew the 1721 was a good amplifier so I wanted to jump straight in and get some serious current flowing through those numerous output transistors. Having attended a number of concerts by the Kodo Drummers of Japan at a number of different venues, I am well placed to evaluate the quality of reproduction of the Taiko drums they are masters of. The Taiko drum has a very distinctive sound signature being constructed from skins stretched over a wooden carcass using traditional techniques dating back to the 6th century and with fundamental modes reaching down to 30Hz. Though a very large instrument, the Japanese musician will use his “Bachi”(Taiko drum sticks) to strike the drum across its entire diameter from centre to rim. Faithful reproduction requires a system with the ability to reproduce the lowest notes with good control, definition and timbre while also retaining the dynamic range and attack of the drum strike. No HiFi system is capable of portraying a perfect rendition of the Taiko but the 1721’s contribution to the illusion was very good. Deep notes were presented with well-controlled power and a real perception of the decaying vibrations of the drum skin. At the other extreme, rim shots were fast, dynamic and tonally textured. Overall, a very credible representation of a complex and challenging instrument (Kodo: Heartbeat 16bit/44.1kHz CD rip).

Another of my favourite test tracks is Michael Murray’s Bach: Toccata & Fugue in D Minor (16bit/44.1kHz Telarc CD rip), an excellent performance on the organ of the First Congregational Church in Los Angeles. The 1721 managed to create a great image of this instrument with good breadth and depth and all the gravitas, power and acoustics you would expect from such a magnificent location.

Moving on to some progressive rock, my favourite live Yes album is: Keys to Ascension 2 (16bit/44.1kHz CD rip). Chris Squires’ distinctive Rickenbacker bass playing was a delight, as I’ve come to expect from a quality system. Jon Andersons’ high register voice is difficult to record well and ruthlessly exposes any tendencies towards sibilance but the 1721 had no trouble on this front. I was able to sit back and simply enjoy the music.

My most recent music acquisition was Bear’s Den: Red Earth & Pouring Rain (24bit/96kHz Qobuz download) so was naturally keen to hear this on new equipment. This a fine example of modern sound engineering and production techniques and a pleasure to listen to if folk-rock floats your boat. The 1721 produced a pleasingly expansive soundstage that was relaxed and never forward or pushy. Voices were clear and uncluttered even on complex passages while cymbals were fast and shimmered cleanly. The atmospheric feel of “Roses On A Breeze” and “Love Can’t Stand Alone” were beautifully portrayed as intended by the artists.

Conclusions:

Having listened to a wide variety of music over more than a week, my overall impressions of the 1721 are that of neutrality, transparency, depth, control, power and effortless detail. Some may call the 1721 lean sounding but that’s because many other amplifiers tend to be designed with a “house sound” which can sound overblown IMHO. Though my speakers are not particularly efficient, I never felt the 1721 was going to run out of power any time soon even on very demanding loud material so I suspect it will make light work of driving those very difficult speaker loads.

Ovation’s mission statement claims their products are “Engineered for Art” and I’m not sure exactly what this means but to quote Peter Walker of Quad, the definition of the ideal amplifier is “a straight wire with gain” and I think Ovation may have had this in mind when they designed the 1721. When an amplifier is this good everything seems to just work and it disappears from the conscious mind and allows you to immerse yourself in the music, which is what it should do.

Ovation offer a five year parts and labour warranty on all their products. With a retail price tag of £6699 including VAT and UK shipping the 1721 power amplifier is not cheap so would represent more of an aspirational product for most HiFi enthusiasts. That said, if you are looking for a power amplifier at this performance level I believe the 1721 is competitive and a serious contender to be considered.

 

Associated review equipment:

Speakers: Modified Townshend Glastonbury Tor Mk1/Townshend Maximum Supertweeters

Interconnects: Nordost Tyr 2 balanced XLR

Speaker cables: Nordost Heimdall bi-wired Z-plugs

 

Images © Ovation High Fidelity.

 

Edited by George 47
0

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.
Sign in to follow this  
Followers 0

  • Recently Browsing   0 members

    No registered users viewing this page.