Atlantic Technology System 250.1 Surround Sound System.

Manufacturer: Atlantic Technology, 343 Vanderbilt Ave., Norwood, MA 02062; 617/ 762-6300

Package Price: $1,826 (not including stands)

Source: Manufacturer loan

Reviewer: Robert Thompson 

It seems as though every time you turn around, someone, somewhere is developing a better mousetrap or a way of improving things so that they work better. Atlantic Technology has been such a company that has built a well-earned reputation on their ability to offer a lot of bang for the buck. Those of you who've been around for a while may remember the Atlantic Technology 250 Surround Sound System, which was a big success for Atlantic Technology and received many positive reviews in various audio publications, including my review in Issue 57. Atlantic Technology went back to the drawing board and revamped the 250 into System 250.1. In fact, by the time you read this, Atlantic Technology will be introducing the System 270, a system that promises to offer even better performance -- although in a higher price bracket (about $2,400). Based on the performance of the 250.1, the 270 promises to be one heck of a product. [We have been promised a System 270 for review in a future issue. - KWN]

Atlantic Technology says that the 250.1 system was designed to meet the greater power, bass, and surround-localization capability of Dolby Digital and other discrete format material. The ".1" designation is carried out throughout the entire 250.1 line, with the front left and right loudspeakers having the model number 251.1 LR, the center channel loudspeaker being the 253.1 C, and the rear surround channel speakers being the 254.1 SR. The only exception to the ".1" designation is Atlantic Technology's subwoofer which is entitled the 262 PMB, (it replaces the 252 PMB). The finish of all the speakers is a simulated wood (black ash) synthetic vinyl wrap.

Some of the improvements include more robust drivers, cabinets that are 50% denser, and new crossovers to handle the increased power demands of Dolby Digital. The long-throw woofers have been redesigned and now weigh more than twice as much as the originals. To meet the surround-channel-localization capability of Dolby Digital, the company developed a new full-range surround speaker, the 254.1 SR. According to Atlantic Technology, this speaker allows listeners to localize intentional rear channel sounds, while maintaining the diffuse spatial ambience on non-localized material. Additionally, Atlantic Technology chose to beef up the power amplifier section of their newer 262 PBM model subwoofer.

A pair of Atlantic Technology 251.1 LR model speakers handles the front left and right channels. The speakers are a straight-forward, sealed-box, two-way design sporting two long-throw 4" polypropylene midwoofer drivers and a ferrofluid-cooled dome tweeter, which is located directly between the midwoofers in a D'Appolito configuration. The drivers are magnetically shielded to prevent their possible interference with a TV's picture tube. The size of the cabinet is 13"H x 6"W x 8.5"D and its weight is listed as 12 lbs. The listed sensitivity is 90dB and the +/ -3 dB frequency response is listed as 50 Hz to 20kHz. The impedance is listed as being 8 ohms with a recommendation that the speaker be powered by an amplifier that is rated from 10-150 watts per channel.

The center channel speaker is the model 253.1 C. Like its siblings, the model 253.1 C is a sealed-box, two-way design. The speaker has two long-throw 4" polypropylene midwoofers and a ferrofluid-cooled dome tweeter, again located directly between the midwoofers. However, unlike the vertical placement of the 251.1 LRs, this speaker is designed for horizontal placement atop a television set. Two L-pads, which Atlantic Technology refers to as a "Midrange Timbre" and "Hi Freq Level" adjustment, are located on the back of the speaker. These L-pads allow for fine tuning of the speaker to the environment in which it is placed as well as equalizing the high-frequency response of the speaker to tone down overly bright center channel information. (An L-pad works like a volume control, maintaining more of a constant impedance on the amplifier as the level of its operation is changed then a simple potentiometer). The drivers are magnetically shielded. The speaker is also supplied with a base which allows users the option of aiming the center channel vertically depending upon the speaker's position relative to the listener. The size of the cabinet is 6.75"H x 15"W x 7.75"D and its weight is listed as 10.25 lbs. The listed sensitivity is shown to be 90dB and the speakers +/-3 dB frequency response is listed as 80 Hz to 20 kHz. Nominal impedance is 8 ohms, with a recommendation that the speaker be powered by an amplifier that is rated from 10-150 watts.

Each of the 254.1 SR surround channel speakers uses two 4" polypropylene woofers and two 0.5" dome tweeters. The drivers are angled and phased to produce ambiance without localization for movie and surround soundtracks. The listed frequency response is 80 Hz to 20 kHz +/-3 dB. The speaker measured 10.5"H x 9.5"W x 6.4"D and its weight is listed as being 8.4 lbs. Nominal impedance is 8 ohms with a recommendation that the speaker be powered by an amplifier that is rated from 10-150 watts.

The 262 PBM uses a 12" polypropylene woofer in a sealed enclosure (the older 252 PBM subwoofer was a bass-reflex design). The enclosure has a built-in 150-watt power amplifier. The max peak SPL is stated as being 105 dB. The listed frequency response is 35 Hz (low pass filter setting) up to 125 Hz. The subwoofer has a built in crossover that is continuously switchable between 60 or 125 Hz. The 262 PBM also has a number of ingenious configuration options built in that allow it to hook up to either line level, (preamp level), or high-level (power amp/receiver) outputs. The subwoofer measured 14.75"H x 19.75"W x 13.75"D and its weight is listed as 53 lbs., (compared to 40.65 lbs. for the 252 PBM).

The system came with two speaker stands, (model 166-ST). The stands are made out of a heavy gauge carbon steel and are painted black. The stands allow the 251.1 LR and the 254.1 SR speakers to be positioned at a height of approximately 28 inches (measured from the floor to the bottom of the speaker). Each speaker is securely mounted in place by means of a bolt that mates perfectly with the back of each speaker, (each speaker has a pre-threaded area to accept these bolts). Each stand tilts the speaker upward at approximately a 5 degree angle. The stand's center is hollow to allow the user the option of threading speaker wire up through the center of the carbon steel directly to the speaker.

The complete System 250.1 has a suggested retail price of $1,826 with one subwoofer or $2,475 with two subwoofers. Each model can also be purchased separately. The 251.1 LR front speakers cost $399 per pair in the standard black finish; 262 PBM subwoofer, $649 each; 253.1 C center channel speakers, $349 each; 254.1 SR surround speakers, $429 per pair. The 251.1 LR and 254.1 SR are also available in white for an additional $20 per pair.

Objective Evaluations: As per my normal evaluation standard, all objective measurements were made after the subjective evaluations were completed. I started the objective evaluations by measuring the frequency response of the loudspeakers. I measured the frequency response of the 251.1 LR (mains) and 253.1C (center) speakers both on-axis as well as at 15, 30, 45, 60 and 75 degrees off-axis horizontally. These same measurements were repeated for the same horizontal positions with the difference being that the microphone was positioned 15 degrees higher and subsequently 15 degrees lower as well (vertically). The purpose of all these measurements is to make a "Summed Response," (SR). The software in my measurement gear allows me to "average" a number of curves together to develop a composite curve. The SR that I obtain from these measurements gives me a better picture of the true frequency response characteristic of the speaker in question. My Summed Responses (SRs) are made by averaging both the on-axis and the +/- 15 degree measurements both horizontally and vertically, (five measurements in total are averaged). I also make SRs for other off-axis measurements as well, although these are not normally shown. The only frequency response graph shown is the SR of the on-axis +/- 15 degree horizontally/ vertically listening window, (with the only exception being the model 254.1 SR surround sound speaker, explained later).

Fig. 1 shows the frequency response of the 251.1 LR, 253.1 C, and the 254.1 SR speakers. Although it might not appear so, all speakers were measured at approximately the same output level. The difference one might notice in dB SPL on the left hand side of the graph in Fig. 1 between the three speakers relates to scaling. I simply chose to put three frequency response graphs on one graph paper instead of using three separate graphs to show the same data, (i.e., I scaled down the 253.1 C and the 254.1 SR relative to the 251.1 LR speaker). Putting all three speakers' frequency responses on the same graph also makes it easier for readers to compare frequency response data between the three different speakers.

[GRAPH OMITTED]

The uppermost curve in Fig. 1 is the SR of the Atlantic Technology 251.1 LR speaker. The curve fits approximately a +/- 5 dB window from about 95 Hz to 16 kHz. The dip one sees at approximately 2.7 kHz is probably caused by the crossover point between the woofers and tweeter. Even though the dip at this frequency can clearly be measured, it was not detectable during the subjective evaluation of the unit. It bears repeating that dips in a frequency response are generally not as objectionable as peaks are. In either case, what is audible is the broadness of the peaks (especially) and dips (to a lesser extent). If a peak occurs over only a brief portion of the audio spectrum, chances are that it will be inaudible, (of course, this is dependent upon many variables). The point is that this speaker sounded very good, even though its objectively measured frequency response might lead one unfamiliar with this type of data to believe otherwise.

At approximately 16 kHz, the response starts to drop off rapidly. This is really of little concern as most adults can not hear above this frequency, coupled with the fact that the speaker is handling the audible frequency spectrum well. The only area of concern to me was the peak centered at 2.076 kHz. This peak covered a fairly large portion of the midrange spectrum. Because this part of the frequency spectrum contains a vast majority, of musical information, (i.e., voice, strings, etc.) I was concerned that it would be clearly audible. Looking back at my subjective evaluation notes, I noticed that I had noted a slight coloration when listening to The Ultimate Test CD's track 49, which has a male voice counting from 1 to 99. This coloration was most evident with this particular track; due probably to there being no other musical instruments with which to mask the sound of the human voice.

The middle curve in Fig. 1 shows the frequency response of the 253.1 speaker. Even comparing the uppermost graph to the middle graph in Fig. 1, it is easy to see that these speakers mate well to each other, (you don't need an exact replica in order to have a good "match"). Note that the speaker's frequency response is also controlled by the two "timbre adjustments" on the back of the unit. I had adjusted both to the manufacturer's premarked positions, figuring that this would provide the best mate with the 251.1 LR main channel speakers. On both timbre adjustments a setting is clearly marked in for matching the 253.1 C center channel speaker best with the 251.1 LR main channel speakers. It is interesting to note that during my subjective evaluation of the complete system, I had adjusted the timbre adjustments on the 253.1 C speaker differently then the marked settings which "should have" mated the unit best with the 251.1 LR speakers. Although not shown in the graphs, I was able to get a closer objective frequency response match between the 253.1 C speaker and the 251.1 LR speaker, with different settings. So be forewarned, even if you own and/or plan to purchase this home theater system, spend some time with the timbre adjustments -- they work!

I also took additional horizontal off-axis measurements (not shown in the graph) at 30, 45, 60, and 75 degrees. I did this to verify that the speaker had no significant "off-axis lobing" errors -- it did not. This speaker did suffer from lobing errors; however, these are not atypical when compared to other center channel speakers using horizontal placement of drivers. All center-channel speakers with horizontal driver placement suffer from some type of off-axis lobing error to one degree or another. Lobing errors are caused by phase cancellation in the speaker's crossover region due to the horizontal placement of drivers as well as by the two woofer's off-axis response, (i.e., as one moves off-axis, the path length changes causing acoustic cancellation). THX-certified center-channel speakers normally get around this by requiring the speakers to have vertical driver placement (i.e., the drivers are mounted in the speaker box one above the other rather then side by side).

The bottom curve shown in the graph in Fig. 1 shows the "pseudo" power response measurement of the 254.1 SR surround speaker. This measurement is not a true power response measurement, per se. The curve is the result of an averaging together of over 40 different measurements taken at various horizontal and vertical angles of incident around the speaker. My opinion is that a surround sound speaker should have a smooth "power response" as opposed to emphasizing a smooth SAR (Summed Axial Response). My rationale for this thinking is that a listener is more apt to hear the total power radiated from a surround sound speaker as most of the speaker's acoustic energy is being sent to the room itself and the reflections from these surfaces arrive at the listener's ears. Compare this to the main front speakers and the center channel speaker which are aimed directly at the listening position and where the majority of the sound impression of the speaker is determined by the direct sound arriving at the listener's ears. The curve indicates that the 254.1 SR speaker has a smooth overall response. The curve fits an overall +/-5 dB window from approximately 132 Hz to 9.558 kHz.

Fig. 2 shows the near-field frequency response of the 262 PBM subwoofer with its crossover set to 125, 80, and 60 Hz. With the crossover set to the 125 Hz setting, the subwoofer reached its maximum output at 124 Hz. At this crossover setting the +/-3 dB frequency response was 73 to 181 Hz. When the crossover was set to the 80 Hz setting, the subwoofer reached its maximum output at 59 Hz. At this crossover setting the +/- 3 dB frequency response was 39 to 84 Hz. When the crossover was set to the 60 Hz setting, the subwoofer reached its maximum output at 39 Hz. At this crossover setting the +/-3 dB frequency response was 30 Hz to 57 Hz.

[GRAPH OMITTED]

Next I tested the speakers' impedance. Fig. 3 shows the impedance of the 251.1 LR, 253.1 C and the 254.1 SR speakers, (in order to reduce graph clutter, no phase information is presented). All three speakers reach their highest impedance of about 15.76 ohms at approximately 114 Hz. Generally speaking, (no pun intended) the resonance frequency of a sealed enclosure determines it lower output capability, below which it begins to roll off at a rate of about 12 dB per octave. This fact correlates well with the acoustic frequency response of the speakers as well. The 251.1 LR had a low impedance of 4.26 ohms at approximately 260 Hz, with a nominal impedance of 7.11 ohms. With both the timbre adjustments set to the "251.1" position on the 253.1 C speaker, it reached a low impedance of 3.92 ohms at approximately 266 Hz, with a nominal impedance of 6.45 ohms. The 254.1 SR speaker had a low impedance of 3.26 ohms at approximately 944 Hz, with an nominal impedance of 5.79 ohms. The information one should get from this graph is that all speakers present a fairly easy load for any well engineered amplifier/ receiver to drive.

[GRAPH OMITTED]

Setup and Subjective Evaluations: I can personally attest to Atlantic Technology's claim of increased weight for the new line of speakers. These speakers are a lot heavier then the older models they replaced. This is due to Atlantic Technology's efforts to reduce cabinet resonance by increasing the cabinet density. As is my standard practice, I conducted a quick and dirty "knuckle rap test" in order to determine how well braced the speakers were. All the speakers in this setup passed admirably. I expected nothing less, considering that I had felt the older models these replaced were well braced as well. What we're looking for on the knuckle rap test is a thick "thud," as opposed to a hollow ringing sound. If a speaker's cabinet resonates excessively, it can negatively affects the sound the speaker reproduces.

I positioned the 251.1 LR speakers approximately 2.5' to the left and right of my television. The 253.1 C center channel speaker was placed on top of my television. One of the nicest things about Atlantic Technology's center channel speaker, and a feature I would like to see incorporated by other manufacturers is the speaker base which it sits on. The base and center channel speaker combination are designed to allow the user to "aim" the speaker in the vertical plane in a number of various positions. This feature helped immeasurably by allowing me to position the center channel speaker so that its sound integrated well with those of the main two speakers. The 262 PBM subwoofer was placed in the corner of the room. The 254.1 SR speakers were placed approximately 6 feet high and positioned to either side of the primary listening position. I used the Rockford-Fosgate Perfect Interface PD-2 Impulse Generator and PD-1 Phase Detector to verify that all speakers were hooked up in absolute polarity relative to each other and that the drivers in each speaker were properly wired at the factory. I adjusted the stereo/Dolby Pro Logic outputs levels between the various speakers by using the Delos DE-3179 test CD (800/364-0645) and my Goldline DSP-30 RTA set to both 1/6 and 1/12 octave mode. Output levels for Dolby Digital playback were adjusted using the Delos DVD Spectacular (DV-7001) test disc. Final settings were made based on a combination of objective and subjective testing.

A Kenwood KM-X1 multi-channel amplifier was used as the main power amplifier for all the speakers, (minus the self-amplified 262 PBM subwoofer). The Kenwood KM-X1 multi-channel amplifier has a rated continuous output of 100 watts per channel into an 8-ohm load when operated in six-channel mode, (although my own testing shows it actually puts out about 145 watts continuous into 8 ohms prior to clipping). Note that the Kenwood KM-X1 amplifier was not used for the objective testing of the speakers. A Carver M 1.5t model amplifier was used for objective speaker testing, because of the Carver's higher output capabilities. Two different surround sound processors were used throughout this test. The first processor used was a Sony TA-E2000ESD Dolby Pro Logic processor/preamp. The second processor used was a Sony SDP-EP9ES for Dolby Digital decoding.

I first wanted to see how well the main/ sub system sounded together without the center and surround speakers playing. I therefore started my subjective evaluation by using the IASCA "Competition CDs" (the 1991, 1995, and 1997 editions). Listening to the track "Just Ahead" by Pat Coil, I was immediately impressed by the overall tonal accuracy and spectral balance the Atlantic Technology system reproduced. When listening to The Ultimate Test CD, track number 49, which has a male counting from 1 to 99, I did note a slight coloration that the AT 251.1 LR speakers imparted to the male voice. Note that I was evaluating in "stereo mode" and not listening to the entire home theater system during this portion of the testing, (i.e., only the 251.1 LR speakers and 262 PMB subwoofer combination).

When listening to both "Evolution" by the Usual Suspects and "The Vikings" by Pomp & Pipes, I felt the sub-bass (10Hz-60Hz) of the system was slightly lacking when listened to at very high volume levels. At more traditional listening levels, averaging around 90 dB, the sub-bass was rated as good. The mid-bass (60Hz - 200Hz) was rated as very good. The mid-range (200Hz-3kHz) appeared to have a slight nasal quality, but this was only slightly evident and then only during select passages within the track.

The spectral balance of this system really shone when I listened to "Agua de Beber" by Ana Caram. When listening to this track, each individual sound was well defined and separate with excellent clarity of the various instruments. I felt that the high-frequency range (3kHz to inaudibility) was ever so slightly "peaky" during select passages within this track, but was good overall.

To evaluate the staging capabilities of the system I listened to a DMP release titled "Truth in Love," by D. Charles & D. Friedman on the CD Junkyard. The Atlantic Technology system really was able to place each instrument in a truly three-dimensional space. To evaluate the speakers' soundstaging and their ability to portray a natural ambience, I listened to the selected tracks from the Test CD 4.1 from Opus 3. When evaluating the staging capabilities of a sound system it helps to shuts your eyes and to have a piece of paper and pencil in order to draw a diagram that correlates with what one is hearing, (i.e., placement of the instruments on the sound stage). When a person's eyes are open, their visual cues tend to cause confusion. During this phase of the subjective testing, I was awestruck by the ability of the speakers to "disappear" and let the music play through. The stage width, height, and depth were very convincing. I felt that the system was able to accurately portray every environment that it was called upon to reproduce.

The sound linearity of a system refers to its ability to accurately reproduce a recording's spectral balance and dynamics at various volume levels. To test this aspect of the speakers I listened to the track "Spyro Gyra" off the 1991 IASCA Test CD. Using a pink noise track from the CD and setting my Goldline RTA to SPL mode, I set the SPL level to 78 dB and listened to the this track, which contains a complex spectrum of musical sounds, (horns, drums, etc.) and is excellent for testing linearity. As I listened, I took detailed notes of the instruments involved, and judged my ability to distinguish the tonal balance between the various instruments, etc. After listening to this track I again played back the pink noise track in order to set the volume level for average playback to 90 dB. The rationale for changing the SPL is to determine whether at a 12 dB higher SPL level the speakers start to compress and change the tonal character of the same soundtrack that I had previously listened to at 78 dB. This same procedure is then repeated at a 103 dB SPL. The Atlantic Technology sounded very good at both the 78 dB and 90 dB levels. At these levels I was unable to notice any compression of the tonal character of the music. However, when I reset the level to 103 dB, the speakers started to compress and there was a smearing of some of the instruments. The compression/smearing was not overly excessive, but it was noticeable at this higher volume level. Remember that the 103 dB was an average level, the peak level hit was closer to around 109 dB. Therefore this is a severe test of a sound system -- 109 dB is pretty darn loud! Before anyone starts worrying about my hearing -- or my sanity -- please note that these are measurements taken at 1 meter -- at the listening position, average SPL levels at were around 74 dB (soft), 86 dB (moderate) and 98 dB (loud).

To test the surround-sound capabilities of the system, I started off with a newly released Telarc CD of Holst's The Planets,(CD-80466). This CD was recorded in "surround sound," [As I point out in this issue's Double Double, I think this phrase on the cover is marketing hype -- the fine print says it is "compatible with" surround sound processors -- as would be any other stereo CD. -KWN] and sounded superb with good envelopment when played back with standard Dolby Pro Logic decoding. I also tried out another surround sound encoded CD, the infamous woofer-killer by Telarc, The Great Fantasy Adventure Album (CD-80342). This CD has killer low frequency sound effects that cause all but the best subwoofers to cry out in pain. When playing back the "T. Rex!" and "Terminator: Theme" tracks of this CD at high volume levels, the 12" woofer of the 262 PBM subwoofer was not up to the challenge. This is not to say that a 12" woofer couldn't be designed to reproduce these tracks with full realism and authority (listen to the Hsu Research HRSW12Va if you're in doubt). When the volume level was turned up too high, the Atlantic Technology 262 PBM started to double and exhibit audible signs of distress. To be fair, there are not too many subs that can pass a torture test like this -- the ones that do tend to start at about $1,000 and go up from there. When playing back these tracks at more realistic volume levels, the 262 PBM sounded fine and unstressed and had sufficient deep bass to "shake the room." Just don't expect this sub to move the kind of air that a world-class sub such the Velodyne or Hsu Research subs can -- it can't.

Finally, I wanted to see how well these speakers could reproduce Dolby Digital musical recordings. I currently only own one such music CD, (the previously mentioned Delos DVD Spectacular test disc). This CD has Tchaikovsky's infamous 1812 Overture recorded in both standard PCM as well as Dolby Digital, (unfortunately for me, this music would not have been my first choice). When played back at more realistic levels, these tracks sound excellent when reproduced via the Atlantic Technology speakers. If the volume level was turned up too loud, the speakers could be made to double, (especially during the cannon shots). However, I must say that with Dolby Digital material, these speakers sounded very good indeed.

By this time in the listening process, I had a fairly good expectation as to what the speakers would sound like with DVD and Laser Disc movie tracks. In this regard, my assumptions were right on target. With good source material, and when played back at more "normal" listening levels, these speakers sounded excellent with whatever disc I feed them. I watched Twister, and was impressed by the ability of the system to "envelope" the listener in a soundfield. One of the friends I had over at the time was very impressed by the ability of these speakers to convey whatever environment they were called upon to reproduce, e.g., tornadoes, rain storms, etc. The "suspension of disbelief" that these speakers were able to create was indeed impressive. In my room, the surround speakers blended perfectly with the main front channel speakers and provided the necessary psychoacoustic cues with which to truly enjoy home theater to its fullest.

The only area that I found lacking was in the ultimate low frequency output and depth. To be fair, I'm used to reference-class subwoofers, e.g., Hsu Research, Velodyne, etc. When the Atlantic Technology 262 PBM subwoofer is compared to these types of subwoofers it comes up lacking. However, the Atlantic Technology 262 PBM costs substantially less then these subs, and when price is taken into consideration, this sub more then holds its own against its similarly-priced competition. As I stated before, don't expect this sub to move the kind of air that a world-class sub can. The only reason for bringing this aspect of the system's performance (or lack thereof) to our readers attention is that I personally feel a lot of the appeal of home theater is in its low frequency special effects channel(s). This is particularly true of "action" type movies. If you're the type of person who enjoys these types of movies and/ or TV shows, (e.g., Star Trek Voyager), then try out these subs in a direct comparison to some other reference-type subs. You may or may not be satisfied with the Atlantic Technology sub's capability, but it bears checking out firsthand via a direct comparison.

So the ultimate question is how much "bang-for-the-buck" does this system offer when compared to similarly-priced home theater speakers? I would have to give this system a "thumbs up," as it does a number of things very well and it has few faults. At this price point, Atlantic Technology is up against some stiff competition from other manufacturers as well. Even so, the Atlantic Technology system more then holds its own when ranked against similarly priced products. If I were shopping for a complete home theater in this price range, I would take the time to seek out and listen critically to a demonstration of what this system can do. Be forewarned to bring your credit card or checkbook, as you're likely to take this baby home once you've been seduced by its wonderful sound. And be on the lookout for System 270 -- if it improves on Sytem 250.1, even at a higher price, it will be quite a product indeed. By the way, Atlantic Technology may also be introducing a new system that will come in at a price just below 250.1. As I said at the beginning of this review, somebody, somewhere is always coming up with a better way of doing things. Atlantic Technology seems to have a few of these people on their payroll!

-- RT