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Product Review
 

Sherbourn PT-7000 Surround Sound Processor and 7/2100 Seven-Channel x 200 Watts Power Amplifier

January, 2004

Yongki Go

 

Specifications:


PT-7000 (SSP)

7.1 Operation

Bass Management: Crossovers at 40 Hz to 150 H

Input Impedance 26 kOhms

MFR: 10 Hz - 20 kHz - 0.5 dB

Component Video Bandwidth: 55 MHz - 3 dB

Rated Output: 2 V RMS

THD: 0.0035%

Dimensions: 4.6" H x 17.12" W x 14.76" D

Weight: 17.6 Pounds

MSRP: $1,500 USA

7/2100 (Amplifier)

Power output per channel: 200 W into 8 ohm, 300 W into 4 ohm
THD: <0.05% at 8 ohm, <.075% at 4 ohm
Output load impedance: 8 or 4 ohm in normal mode, 8 ohm minimum in bridged mode
Input load impedance: 20 kohm (balanced or unbalanced)
Input sensitivity: 1.1 V (balanced or unbalanced)
Power bandwidth: 5 Hz to 75 kHz
S/N ratio: 100 db wideband, 110 db A-weighted
Power requirements: 120 V, 2 x 15 A
Dimensions (W x H x D): 19" x 7"x 17.7"
Weight (in carton): 115 lbs
MSRP: $ 2,850 USA

 

Sherbourn Technologies

 

www.sherbourn.com 

Introduction

Sherbourn Technologies is a young company that has been known for its affordable high quality power amplifiers. In fact, Sherbourn was the first to introduce a five-channel amplifier incorporating monoblock design, with each monoblock having its own toroidal transformer (the model 5/1500 amplifier).

As an extension to that design, Sherbourn has introduced a seven-channel monoblock amplifier, the 7/2100, which is one of the products reviewed here. Recently, the company has expanded its product line to also include a preamp/processor/tuner, the PT-7000, which is the other product in this review.

The PT-7000 preamp is 7.1 capable and was designed to match cosmetically with the 7/2100 amplifier. Both the PT-7000 preamp and the 7/2100 amplifier are finished in black with anodized faceplates. There is nothing fancy about the appearance of this matching pair, but they do possess a clean no-nonsense look. They seem to be solidly built as well.

PT-7000 Features

First of all, you may be aware that there are other surround processors from other companies that look very similar and have similar features to the PT-7000, such as the Outlaw Model 950 and the Atlantic Technology P-2000. I found out that they are indeed based on the same design, as they are outsourced from the same Asian OEM company. Besides their faceplates, the main difference among them is the components used inside.

Note that many companies outsource their product manufacturing to OEM suppliers who simply build the products to that specific company's specifications.

The PT-7000 preamp uses a Cirrus Logic chip for its surround processing. It is capable of processing most of todayís surround formats, which includes DD, DD-EX, DTS, DTS-ES, Dolby Pro Logic (DPL), DPL II, and DTS-Neo:6.

In addition to these modes, the PT-7000 also offers the so-called Cirrus Extra Surround, which is a decoding algorithm to create 6.1 or 7.1 output from matrix encoded or discrete audio signals. The Cirrus Surround in this preamp is available as an enhancement to DPL II and DD modes.

The PT-7000 is equipped with 24 bit/192 kHz DACs and 24 bit/96 kHz ADCs from Crystal Corporation. The crossover settings are selectable in the 40 Hz to 150 Hz range (in six increments) and can be adjusted independently for the front, center, and surround speakers. The capability to independently adjust the crossover of the three speaker groups is a very nice feature, but it has to be used with caution. If one has small surround speakers, one might tend to use higher crossover frequency for the surrounds. This is all fine, but beware that bass frequency higher than 80 Hz can be localizable. So the use of higher than 80 Hz crossover frequency, especially for surrounds, could mess up the overall surround effect. I suggest using 80 Hz or lower crossovers all around, which also means that the satellite speakers used should have lower than 80 Hz frequency response.

The input output connectors on the back of the PT-7000 are neatly arranged and should be more than sufficient for a typical home-theater setup. On the audio side, there are nine stereo analog inputs, six digital inputs (four optical and two coaxial), and one 5.1 analog direct input. All the stereo analog inputs can be bypassed through a push of a button on the front panel or on the remote control. This stereo bypass mode defeats the DSP processing section of the preamp, but the main speaker crossover remains active. So in the bypass mode, you can still use your subwoofer to augment your main speakers if necessary.

Basic bass management feature is provided for the 5.1 input, which can be activated from the switch on the back. Setting this switch in the ON position activates an 80 Hz high pass filter for the 5.1 direct input, except the subwoofer. This feature sends signals of 80 Hz and lower from the five channels to the subwoofer. In the OFF position, full range audio signals will be sent to all channels. This preamp has a set of 7.1 analog outputs to drive your amplifier and also two digital outputs (1 optical and 1 coaxial). A stereo second-zone output is also provided. With it, you can send a second source signal to another amplifier in a different room or another device (e.g., for recording).

On the video side, the PT-7000 can accept five composite, five S-Video inputs, and two sets of component video input. The component video switching has a bandwidth of 55 MHz, but 100 MHz would have been preferable. This preamp converts automatically from composite to S-Video or vice versa, which can be handy in some situations. One set of outputs is provided for each type of video connection. Other types of connections on the back panel of the PT-7000 include FM/AM antenna terminals, DC triggers, and remote extension jacks.

The front panel of the PT-7000 is relatively clean, but functional. You can set up and operate the PT-7000 from the buttons on the front panel alone. The display in the middle of the front panel shows the operating status of the preamp in green lettering. Depending on the mode, this two-row display indicates the program source, surround mode, tuner frequency, volume level, and some other preamp operating information. This display is dimmable by changing the brightness level in the setup menu.

The PT-7000 comes with a programmable remote control. I have encountered the exact same remote several times, bundled with other equipment that made a stop in my audio rack. But even though I have had some experience with this remote, I never grew accustomed to it. It is quite a versatile remote, and probably one that could replace your other componentsí remotes, but in my opinion, the layout of its buttons is not very logical. Your mileage may vary though. The nice thing about the remote is it is back-lit, so using it in the dark is not a problem. Pretty much all the functions of the PT-7000 can be accessed using the remote control.

7/2100 Amplifier Features

Let me start by saying that the Sherbourn 7/2100 amplifier is a heavyweight monster (100 pounds). It packs seven monoblock amplifiers capable of delivering 200 W each into an 8 ohm load (300 W into 4 ohm) in a single chassis. Some people use the raw measure that the heavier the amplifier, the better. If you are from that school of thought, then you will be very happy with this amplifier. But Iím not sure if your back is with you on this. Lifting this amplifier is an adventure, not only because of its weight, but also because no lifting handles are provided. To think of it positively, burglars will think twice about taking this thing.

The 7/2100 amplifier uses two power chords, which should be connected to two different electrical outlets. This is because the 7/2100 may draw more current than a single outlet could provide (a typical outlet could handle up to 15 A of electric current), especially when it is used to drive low impedance speakers. In my opinion, this is a more elegant solution than requiring one to install a dedicated 20 A outlet, as some high-current amplifiers from some other manufacturers require.

The 7/2100 amplifier can accept balanced or unbalanced inputs. High quality five-way binding posts are used for the output terminals. All the input and output connectors are gold plated and seem to be very robust, so I have nothing but praise for the build quality of this amplifier. While the spacing of the input terminals is nice, the between-channel spacing of the binding post output terminals is a little too close. The spacing was fine if banana plugs are used, but with spade plugs, I found that the spacing was too tight.

One of the nice features of the 7/2100 amplifier is that it is bridgeable. Three pairs of the input channels on the back are separately grouped, and a bridging switch is provided for each group. Each bridged pair can produce up to 400 W into 8 ohms. With the bridge capability, you can configure this seven-channel amplifier into a six-, five-, or four-channel one depending on your need.

Another nice feature of the 7/2100 amplifier is the inclusion of the Load Detection System (LDS) switch for checking the correctness of the speaker connections. This switch can show the status of the speaker connection for each channel through a colored LED without needing an ohmmeter or a walk through. Green LED indicates a good speaker connection and correct speaker impedance, orange indicates an open circuit or high speaker impedance, and red indicates either a short circuit or a too-low speaker impedance. When the indicator shows orange or red for a channel, it is suggested that you check the speaker connection for that particular channel.

Except for the power on/off button, a small blue LED indicator, and the Sherbourn logo, nothing else clutters the faceplate of the amplifier. This amplifier can be put in always-ON mode or remotely triggered in two ways: using automatic signal sensing or 12 V DC voltage.

Use and Performance

The setup of the parameters in the PT-7000 to get the best out of your speaker configuration is relatively easy, and the procedure is quite logical. If you have some familiarity with a multi-channel surround processor and can navigate yourself through the PT-7000 menu system, then you need only minor help from the manual, which by the way explains everything in good detail and is clearly written. The on-screen display capability of the processor just makes the setup process easier. The PT-7000 menu is simple, but covers all the necessary basics, such as speaker configuration, speaker delay (by distance from the listener), and level calibration. In addition, you can preset the default settings for each input, which adds to your convenience, because you donít have to change the settings every time you change input. Once you have it setup and running, you can just use the preampís front panel display to check its operating status. My only complaint about the display is that the lettering is too small. I sat about 10-12 ft from the preamp and at that distance in full brightness, the display was still readable but not without some effort. The display is dimmable to half brightness, but you cannot turn it off altogether.

I evaluated the performance of the combo PT-7000 and 7/2100 in a two-channel setup, as well as 5.1 and 7.1 setups. First, let me say that in any of those configurations, this combo always displayed solid performance and never disappointed.

The PT-7000 preamp is not only feature-laden, but it also performs admirably. As far as Iím concerned, it didnít possess a serious operational quirk. Sure there were some operational features which I found to be not to my liking, but they were relatively minor. For example the speaker distance adjustment is only in 1 ft increments, not in 0.5 ft as Iíd rather have, and it didnít provide separate adjustments for the side and rear surrounds (if you have an odd setup where the difference in distance between the side and rear surrounds is large, this might be a problem). Also I would prefer finer channel volume level adjustment than just the 1 dB steps provided in the PT-7000. The lock-in to digital signal was also not immediate, usually took about 2 seconds. My biggest complaint was on its channel trim feature. When the channel levels were changed using the on-the-fly level trimming, my saved calibration levels were also changed. And to get back to the intended calibration level again, one has to change it manually. If you forget what your calibration values were, you apparently have to calibrate it again. On-the-fly channel trim feature is of course nice to have to quickly adjust to various soundtrack mixes, but I prefer one that does not interfere with my saved calibration.

The tuner section in the PT-7000 was not as good as some others that I have tried in receiving FM signals. I used my Terk powered antenna with the tuner and tried to tune in several FM stations that I often listen to. I could not get clear reception with some stations that normally I could easily get with my mini-system or my car FM radio.

Once set up correctly, the PT-7000 delivered solid all around performance. This preamp did not add any harmful artifacts to the sound, such as harshness or edginess. In stereo mode, I noticed that the presentation through the PT-7000 was slightly forward compared to my stereo preamp, the Adcom GFP-750. Details and balance were quite excellent. Vocals might not be as lush as through my Adcom, but it was not something that you could easily notice without doing a comparison. The soundstage through the PT-7000 was also somewhat shallower, but this was only obvious on some recordings.

On multi-channel music through its 5.1 direct input, the PT-7000 did what a good multi-channel preamp should do, which is to deliver clear and transparent sound. With the current state of multi-channel recordings, the standards of which vary significantly from one recording to another in terms of the portrayal of the listener position with respect to the soundstage, those were the only things one could ask for to get good multi-channel music playback at home. The provision of bass management for its 5.1 channel input is something that I applaud and I think all surround processors should have some sort of bass management feature on its multi-channel direct input. Manufacturers should remember that most of us donít have the space or resources for accommodating full-range speakers all around.

In a home theater application, I was very pleased with what PT-7000 delivered. I never felt the lack of clarity or impact in my movie watching experience with this preamp functioning in the centerpiece of my system. Its surround performance, in my opinion, could hold the ground well against the competition in its price range. The Cirrus Extra Surround processing included in the PT-7000 was a nice bonus. Not only it lets you use all your speakers in 7.1 channel setup, for less than 7.1 signals, but it also enhances ambience surround envelopment. Although I still prefer the effects created by the Lexiconís Logic 7, nevertheless the Cirrus Extra Surround is a nice enhancement to have.

The PT-7000 was also no slouch in handling video switching. It was relatively transparent and it did not cause any noticeable degradation in picture quality.

Part of the reason why the performance of the Sherbourn combo never disappointed me was the 7/2100 amplifier. Regardless of how good your surround processor is, without a good multi-channel amplifier to match it, you wonít get a good result. And the 7/2100 amplifier is more than just good, it is monstrously great! Delivering clean sound with excellent clarity was never a problem with this amplifier, neither was playing loud without strain or delivering bass punch when called for. The 7/2100 sound was quite neutral, but might tip ever so slightly towards bright.

During my evaluation, I had a chance to compare the 7/2100 with another great multi-channel amplifier, the ATI AT-1505 (5x150 W into 8 ohms), which Iíve owned for many years. Through the same set of source, preamplifier, speakers, and cables, the sound with the 7/2100 was brighter (not necessarily bright) than with the ATI. The Sherbourn played slightly cleaner with ďdarkerĒ background than the ATI, which might be attributed to its monoblock design. Both amplifiers did well in the bass department, but with some noticeable differences. The ATI delivered more bass output than the Sherbourn, but the bass of the Sherbourn seemed to be punchier and more controlled. In terms of other sound attributes, such as soundstage, image, and detail, both amplifiers performed very similarly. I would be happy with either of these amplifiers, but if I had to choose one now, I would give an edge to the Sherbourn because of its slightly cleaner sounding and more controlled bass. But as with any audio equipment, your taste and your other equipment should be the deciding factor in choosing the right amplifier for you.

The bottom line is the Sherbourn 7/2100 is a lot of amplifier for the money. Its $2850 asking price may sound expensive, but when you consider that you get more than 1400 W of amplification with it, then it is not. For the wonderful performance it delivers, this product represents one of the best values in a seven-channel power amplifier available right now.

Conclusions

Sherbourn has produced a solid combo in the PT-7000 preamp/processor/tuner and 7/2100 seven-channel amplifier. The PT-7000 preamp packs extensive features and delivers respectable performance. It can definitely hold its ground well against the competition in its price class. The 7/2100 is a great amplifier that Iím sure will complement many home theater systems nicely. This superb sounding amplifier has ample power to satisfy even the most power hungry system. At $4350, the combo is not cheap, but in the world of separates, its price is very reasonable, especially considering you get so much bang for the buck.

 

- Yongki Go -

 

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