Product Review - Cinepro 3k6 SE Gold Six-Channel Fully Balanced Power Amplifier - June, 2001
John E. Johnson, Jr.
Power: 425 Watts RMS Per Channel x 6 at 8 Ohms, 20 Hz - 20 kHz; 700 Watts RMS at 4 Ohms; 1200 Watts RMS Per Channel x 3 Mono Bridged
MFR: 3 Hz - 185 kHz ± 3 dB
THD: 0.15% at Full Output
Input Impedance: 30 k Ohms; Balanced XLR and Unbalanced RCA Input Jacks
8" H x 19" W x 16" D
Weight: 86 Pounds
Cinepro, 1030 Vicente, San Francisco, California 94116; Phone 415-564-6300; Fax 415-564-6324; E-Mail email@example.com; Web http://www.cinepro.com
These days, it is easy to spend a ton of money on a processor, receiver, power amplifier, cables, and speakers. And, I mean you can spend six figures. The problem is how much improvement do you get for the top dollar item vs. mid-hi-fi stuff? In some cases, you get plenty, while with others, maybe not so much. Sometimes, even the chassis of a high-performance product can be thousands of dollars in the MSRP. Well, Cinepro is here with a fantastic muscle amp that is a top performer, with parts quality of products costing several times more, and maybe even a few things the others don't have, such as gold plated circuit boards.
The Cinepro 3k6 SE Gold is a six-channel, 425 watt per channel (into 8 Ohms), power amplifier that just begs to be in your home theater. Their multi-channel amps have been very popular with professional installers for some time, hence the name Cinepro, which does have the ring of the pro market. At 425 watts per channel, the 3k6 is probably the most powerful multi-channel amplifier in the world. And, these 425 watts have the power supply to back them up. A huge 4.2 kW toroidal power transformer delivers ± 95 volts to six 25,000 µF capacitors, for 677 joules of energy storage. That is one big power supply! There are three voltage gain stages, and the output stage of each channel has fourteen 250 watt bipolar transistors. LEDs on the front panel light up for each channel when there is a signal, and there is an additional LED for each channel in the situation where you overdrive the amplifier. I never encountered such a situation, even with electrostatic speakers, so I think the only purpose they would serve is to make you feel more secure when cranking a Stallone movie.
Below is a photo of the inside of the chassis. The monster toroidal is at the bottom right corner, and next to that on the left is the power supply circuitry. At the top of the photo can be seen one of the three two-channel amplifier PC boards. Each channel has 14 output devices. The rear panel (top of photo) has a dual fan, which runs very quietly all the time. This keeps the amplifier cool whether or not it is being driven hard. When the amplifier is first turned on, a special circuit turns on the fan at a mid speed level, then powers it down to a point it is barely audible even when standing close to the amplifier and no music is playing.
A close-up of the power supply board (below) shows the star grounding system (red arrow), which helps give the Cinepro its incredibly low noise floor. Instead of having ground wires from various circuits go to the nearest ground buss, or to the chassis, all ground wires lead back to the same point. This means no difference in ground potential from circuit to circuit, and thus, lower noise. The power supply capacitors are underneath this board. The yellow color of the boards is due to gold-plating, on top of nickel, on top of the 4 ounce copper traces (4 ounce means that the circuit board has 4 ounces of copper plate before the circuits are etched into it). This eliminates any oxidation of the traces. Wiring is solid silver. Absolutely nothing has been spared in quality here.
The rear panel has balanced XLR and unbalanced (gold-plated) RCA input jacks for each channel. You can see from the photo, below, that the fans are really pretty big. I have no problems with fans as long as they are quiet, which these are. I could not tell that they were on, even with my head very close to the amplifier.
A close-up of the input jack set on the right side of the panel (below) shows that each pair of channels can be run balanced, unbalanced, dual (each channel separate), or mono (the two channels bridged). You can also lift the ground (toggle at bottom of photo).
The output sets of jacks are on the left side of the rear panel (shown below), which are five-way binding posts. Although this would not affect the sound quality, I suggested to Cinepro President Eric Abraham that he add solid metal, gold-plated binding posts for the speakers, just to match the rest of the package. That will probably happen shortly.
I tested the 3k6 SE Gold with a Toshiba SD-6200 DVD player, Yamaha DSP-A1 Receiver (pre-outs to the Cinepro), Krix Esoterix Speakers, Threshold ES-500 Full-Range Electrostatic Speakers (ESLs) , and Nordost Cables. A PS Audio P1200 served for clean AC supply.
The first thing I discovered is that the 3k6 is so powerful, it could overdrive the low frequencies (~ 40 Hz) on our ESLs, which we used for the front main channels. From my past experiences with these speakers, I know that this takes massive power capabilities. Many amps just can't handle this. They clip, and the low frequency voltage just does not get delivered. So, in order to use the ESLs with movies and deep bass, I had to reconfigure them with the receiver's bass management so that they crossed over at 80 Hz. We are replacing the DSP-A1 with a Theta Casablanca II, which will let us use a lower crossover frequency, and still not have the panels overdriven.
Usually I can hear a hiss in the speakers from a power amplifier under test, but the 3k6 is absolutely quiet. No hum either. The low noise is partly a result of the star grounding, but also because the 3k6 is fully differential (balanced circuits). If you use the balanced inputs (the Theta Casablanca II version we ordered is fully differential, with balanced outputs), you have a fully balanced amplifier system. The RCA input jack connects one of the balanced legs to ground. Even so, I could detect no noise when I used unbalanced interconnects.
The sound quality of the 3k6 is spectacular! It is one of the cleanest amplifiers I have ever heard, and it plays with this clarity at very high volumes. The mid-range remained un-congested no matter how loud we went with it. Our surround sound music CDs and music DVDs just sizzled with excitement. Of course, we need to remind you that it is not good for your ears to play a movie at a level where the 357 magnum is as loud as it would be in real life. But, what is important here is that even when you watch the movies at a safer (80 dB) level, the 3k6 has the power to reproduce transients that occur at the beginning of sounds at proper levels with respect to the rest of the sound. Nevertheless, for those times when your friends are over, and you just can't resist showing the 3k6 off, their jaws will drop when they hear what this amplifier can do. We use a Sony LCD front projector on a 90" Stewart screen, and having a sound as big as the picture sure does make a difference! You might wonder what to do with that sixth channel. Well, with THX Surround EX, DTS ES, and DTS Discrete 6.1 rearing their heads, the 3k6 is right in step. You could also bridge two channels for higher power to the center, or bi-amp the center channel speaker.
The ultra quiet background coupled with a large overhead in power reserve give the 3k6 an unheard of dynamic range of 124 dB. The dynamic range is the difference between the softest sounds (which require a low background noise) and the loudest sound (which require lots of power). It means that very subtle details can be heard, along with the high demand transients. This sort of capability is what will give you a real movie experience.
One of the most beautiful aspects of the 3k6 is that it is not a complicated design. The chassis is not stuffed with boards and chips. There are just a few gain stages. What Cinepro has done is simply build an enormous power supply using the best parts, and the rest is easy. Not much negative feedback has to be used, and yet, the bandwidth is large. Lots of big Motorola transistors, Rel-Caps, Vishay resistors, etc. It's so simple this way. Massive raw high quality power. That does not mean it will be inexpensive to keep it simple, but at $7,500, this is one of the great products out there. Although there is a no-questions asked money back guarantee, I can't imagine anyone letting this thing go once they have it. Multi-channel sound doesn't get any better than the Cinepro 3k6 SE Gold.
- John E. Johnson, Jr. -
© Copyright 2001 Secrets of Home Theater & High Fidelity
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