Operetta Review
I was enjoying the sound from Dali Helicon 400 floor-standing speakers with an Arcam AVR300 receiver
and Arcam DV79 DVD player. However, I wanted more slam and dynamics on some of the music
material that I was listening to. Given that I had the Krell Theater Standard 7.1 Surround Sound
Preamp/Processor and the Krell Theater Standard Amplifier nearby, I thought I would take the Krell
amplifier and hook it up to the pre-outs on the Arcam receiver. My hope was that this would drive the
Dalis better and give them more control, slam, and dynamics. Not that the AVR300 was lacking in any
way, but I just wanted more.
After having everything hooked up and playing the same music material again, there was an improvement in
the sound. However, there was not as much as I thought there would be given that I was adding an $8000
amplifier to the mix. The amplifier didn’t seem to have the power and authority as when it was hooked up
to the Krell preamp/processor. When the Krell was hooked up to the Arcam, it was as if the sound was
thin and a little dry. It was certainly not worthy of adding $8000 to your system. I wondered why this
was. The Krell amp sounds great when paired with Krell’s preamp/processor. Why such a big difference
when pairing the Krell amp with the Krell preamp/processor versus pairing the Krell amp with the Arcam
AVR300 receiver’s pre-outs? I was expecting there to be a small difference but not this big. It was almost
not worth adding an additional amp to the pre-outs of the AVR300. So I did some investigating.
It turns out that there is a dilemma with most receivers on the market today. Most receivers are trying to
do quite a bit of tasks at a low price point. As the saying goes, “You get what you pay for.” But that
could be kind of frustrating to the consumer who may be on a budget and purchases a surround sound
receiver for his/her home theater with modest power and hopes one day if he/she needs more power that
they can simply use the pre-outs to a high-powered outboard amplifier, and they will have all the power
they need for their system.
Here’s where the problem lies. While there are great amplifiers out there like the Krell Theater Amplifier
Standard, these amplifiers have low input impedance (10k Ohm) and require preamp/processors with high
outputs to drive them. Today, most surround sound receivers don’t have high enough pre-outputs to drive
these amplifiers to their fullest potential. This is where Jaton Corporation’s new Operetta AP5140A
amplifier comes in to save the day.
A couple of months ago, Ronnie at Jaton Corp. contacted me about auditioning the Operetta, their brand
new amplifier that was a showstopper at this year’s 2007 Consumer Electronics Show in Las Vegas,
Nevada. When I received the specs on the amplifier, I was very curious. It was 70 watts x 5 into 8 Ohm
and 140 watts x 5 into 4 Ohm. This didn’t seem like a whole lot of power as you see most receivers
having 100 plus watts per channel x 5 or even 7 these days. I didn’t understand why anyone would make
a stand alone 5-channel amplifier with no more power than what you can buy in a receiver for about
$300.00. I replied to Ronnie and agreed to audition their new amplifier.
Upon receiving the package, I was initially shocked by the weight of the Operetta. This amplifier weighs in
at 50 lbs., more than twice as much as most surround sound receivers. Now, I was even more curious, so
I took the amplifier up onto the test bench and took the top off to look inside. What I found were 5
individual amplifier modules, each with their own heat sink, and a power supply with 2 large turroidal
transformers and counted
180,000 uf of filter capacitance at 35v. Wow, this amplifier has some power behind it!
I quickly put the top back on and decided to try it out with the Arcam receiver’s pre-outs and drive the
Dalis with two of its’ channels. After hooking everything up, I turned the system on and let it warm up for
about 30 minutes. I then tried some of the music material that I had been listening to previously. And now,
I had the slam and dynamics I was looking for when adding an external amp to a receiver such as the
Arcam AVR300. While this wasn’t quite up to the Krell Theater Standard 7.1 preamp/processor and
Krell Theater Standard Amplifier combination, it was a definite sonic upgrade over using the AVR300’s
internal amps, and was much better than coupling Krell’s amp with the AVR300’s pre-outs.
Why did this work so much better? Here are a few of the things I found. First, the Operetta’s input
impedance is very easy to drive at 55k Ohms. This amplifier can be driven easily with most tube preamps
and modestly priced receivers. Second, this amplifier has a power supply that is equal to other amplifiers
that have 200 watts x 5. This amplifier is very conservatively rated. Like the Krell amplifier, it will double
its power into 4 Ohms. Not too many other amplifier manufacturers can make this claim as they have big
amplifier specs but limit their power supply. This combination limits the output power to your speakers
when they need it most when dropping in impedance.
In conclusion, while not quite the Krell Theater Amplifier Standard, it’s also not $8000. If you’re on a
budget, the Operetta will deliver the goods. It’s an excellent amplifier for someone who needs an upgrade
on their surround sound receiver or needs a good solid state amplifier to couple with their tube preamp..
Dynamic, detailed, and an open sound stage at normal listening levels with reasonably efficient speakers is
how I describe the sound of this amplifier. Hook the Operetta up to a power regenerator like the PS
Audio Power Plant Premier, and it sounds even better!
Bernard Vooght, President
Vooght Custom Audio/Video Systems