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Meridian 551 integrated amp

The Voice Of Experience

[Meridian 551]
[Italian version]

Product: Meridian 551 integrated amp
Manufacturer: Boothroyd-Stuart - UK
Approx. price: US$-Euro 1400
Test sample: loaned from distributor
Reviewer: Dejan Veselinovic

A long, long time ago, in a galaxy far, far away ... British company Lecson produced an amplifier in the early 70-ties. It was odd shaped for the time, being a cylindrical column. It offered lowish power, around 30-40W or so, yet inside, it was advanced for that time, offering a fully complementary architecture in days when that was a rarity. By sheer accident, I had the opportunity to hear it not long after it was featured in a then-new Italian audio publication, called "Suono" (issue No. 20-something), which kindly also provided circuit diagrams (from which you could see that the power was provided by 2N3055/BDX18 complementary pairs). That unit was designed by a man I first heard of then, one Robert (Bob) Stuart.
Well, Mr Stuart has come a long way since those early days. In 1977, with his partner, Mr Boothroyd, he founded a company called not surprisingly Boothroyd-Stuart. One of their early lines was called Meridian, and as time passed, they became better known by the Meridian monicker than by their full name.

Today, Mr Stuart is the chairman of just about every committee dealing with digital sound you can think of and he occasionally finds the time to write highly instructive articles on digital sound for reputable magazines such as America's "Audio". But still better than that, Mr Stuart devotes much of his time making some quality audio gear, and we look at his smallest and only integrated amplifier model here, memorably named 551.

Manufacturer's specifications

The amp is of precisely the same width and heigth as the recently reviewed 506 CD player. From the outside, it even looks the same, save for the power on/off rightmost bar - it's yellow on the CD, but red on the amp. Of course, the text on the fascia proudly declares this to be model 551 integrated amplifier. On the front, just below the dark perspex cover of the LED matrix display, you'll find, left to right, serelectors for source, copy, speakers, mute, display, volume up and down and power on/off. That's it.

Actually, the power on/off is really a standby mode on/off switch, as the proper power on/off switch is located at the back, as part of the switch, IEC socket and spare fuse holder package. Below it, you'll find two DIN sockets labelled "Comms"; they are intended for connection to other Meridian equipment, one being the input and the other being the output serial line. Next come 8 pairs of gold plated RCA Cinch sockets, from left to right: Pre-amp Out (for biamping), Tape Out, Tape 2 (these being the input sockets, while Tape Out are the output sockets for this full Tape Monitor loop), TV, Tape 1, Radio, CD and LP. No phono RIAA equalization is provided as is, but it is an after-market option, or tyou can have the dealer install it right away - a nice touch.

Above the Cinch sockets, you'll find a 6.3 mm headphones jack (Halleluyah! There are still some sane people left!!!), two fuse sockets and speaker binding posts for one pair of speakers. It seems Mr Stuart doesn't believe in biwiring, or perhaps thinks biamping is much better - so do I, but I also know it's soooooo much more expensive. The binding posts will accept 4 mm banana plugs, but will not accept bare wire over 3 mm - strange and not very clever, I'm afraid.

The top of the substantial case is again covered with dark glass, lending the unit a very neat appearance. However, instead of smooth sides, this time round the sides are in fact heat sinks - and generous ones, at that. They are all of 300 mm wide, 82 mm high and 40 mm deep; off hand, I'd say their radiating area is no less than 1,900 sq. cm of radiating area per channel. Not at all bad for what is notionally a 65W per channel integrated amp.

As for the remote, well, the same remote is NOT supplied with the unit, but is an optional extra. This is rather a strange decision at first glance, but it has a certain logic behind it - Meridian expects you to purchase at least the CD player and the amp as a system, and a remote is included with the CD player, so why charge you twice for what you need only once?
And if you should go for the amp by itself, well, you can always buy the remote as an extra. And you will indeed have to buy it, since much of the unit's programming is best done from the remote - sometimes, it's the only way to do it.

Program? Yes, program. This is a programmable integrated amplifier. You can decide what you want your input sensitivities to be like, so you don't have changes of relative loudness when switching from one source to another, and you can avoid overloading the amp from uncommonly active outputs of upstream electronics. So, to quote Meridian's literature:

MM input (if available): 0.5 - 3 mV for 5 cm/sec @ 1 kHz
Overload at 47 mV @ 1 kHz
Load 47 kOhms // 100 pF
MC input (if available): 38 - 210 uV for 5 cm/sec @ 1 kHz
Overload ?
Load 220 Ohms // 10 nF
Line inputs: 27 - 150 mV, 20 kOhms
Output: 65W per channel into 8 Ohms
100W per channel into 4 Ohms
Headphone output: 2V maximum
Distortion: Less than 0.05%
Noise and hum: < -90dB high level analogue inputs
< -70dB for MM input
< -60dB for MC input
Dimensions: 88 x 321 x 332 mm (Height x Depth x Width)
Weight: 10 kg
Consumption: 30 VA quiescent, 300 VA maximum.

As you can see, the power consumption is rather healthy, which is indicative of circuits not likely to run out of power supply juice.

No pictures of the inside, I'm afraid - it would appear Mr Stuart doesn't want anyone to see how he makes his stuff. For the first time in my audio life, I ran against hexagonal screws I had no driver for, in spite of my rather generous supply of tools, metric and otherwise. Now, I consider this a bloody stupid thing to do, a very, very British thing, I've had this sort of thing happening before on house appliances from UK, which is why I have exactly none at this time. What do they hope to achieve?
If anyone really wants to get inside, he'll do so no matter what they stick on, if in no other way, then by tearing the screws apart. So what's the point? To force technically inapt users to go to the appointed service agent, who beside the tools, is also equipped with a skinning knife? Poor show, Mr Stuart, one would expect something a little more intelligent and less cheap from such a company.

Anyway, ...


As expected, the 551 produced some very fine sounds when playing quietly. The level and more important, the quality of the details were top notch in every respect. One could hear right into the middle, say a band playing together well, but one is able to hear into the mix and listen to just one player among them all. Noise was far from audible, despite relatively modest specifications - it makes one wonder how other manufacturers manage to make such bold claims and keep their faces straight?

Anyway, the bass lines were well moderated, deep and with power, yet not overblown, neither leading not following, they were just there. While in truth they lacked neither extension nor real weight needed to be convincing, they were a little too well behaved for my liking. That was just fine with classical music, even chamber and lighter acoustic music, but began to be noticable with rock, and especially very hard rock. Not bothersome, not wrong, not out of place, just a little too gentlemanly for my liking.

The midrange was just right to a fault - absolutely nothing to say there and stay honest. Just the right tempo, just the right weight and speed, in fact, all of it is just right. Much the same could be said of the treble as for the bass - it's all there, it's light and airy, but a touch too controlled.


With my JBL Ti600, Meridian's 551 was at home all the way, and then some. I think they complemented each other exceptionally well, quite out of the ordinary. Ti600 are relatively efficient at 91 dB/1W/1m and are a well behaved load. This means that they will not stress much lesser amps than the Meridian, who in turn drove them all the way up to ear shattering levels without so much as blinking.
The speakers are full of life, perhaps unusually so, and seemed to compensate for 551's slightly sedate character well, and as a team they produced some impressive sounds. Classical music seemed to especially benefit from this fortituous marriage, joined together and blessed by Reverand van den Hul's 352 Hybrid cables. Rock was very good too, but somehow not as impressive as classical music.

The AR94s were a somewhat different story. They are very neutral in character, but are far from being an easy load. The stress showed on 551 insofar that its heatsinks turned from lightly to pretty warm (while still not hot). Also, some of the transparency of the amp appeared lost, as if the strain of driving the ARs was a little too much for both power and finesse. Let me put it in another way - H/K's 680 is merely 1dB more powerful, yet drives these speakers with much more ease, even if it also turns warmer than usual.

The 551 however remained perfectly in control of all three speaker pairs I tried it with, including the AR94s. It simply showed that it lacked the true grit needed for these speakers. Also, I must add that in all honesty, the small changes in finesse noted above were indeed small and one had to really listen for them to catch them. In other words, if you're not very experienced, you're not likely to notice them, and even if you do, they are small enough to be negligible.

Overall sound

Meridian's 551 integrated amplifier is an obviously competently constructed unit. Its only subjective failing in my view is a little too much control, reminding me of an English gentleman in full Burberry suit coming to a summer beach party. But his disposition is such that he blends in.

Perhaps that's 551's most important characteristic - it blends in, fits itself square in the middle and plays music. It seems it isn't as load tolerant as one might hope from such a company and at such a price, at least judging from its slight stress driving AR94 speakers and in comparison with H/K's 680 model at just under one half the price, but this should not be taken too literally - it isn't load sensitive, it just isn't as tolerant as I would have liked it to be.

It will produce a seamless soundstage from top to bottom, its only subjective failing being that it seems a little too laid back, too restrained.

In many ways, it reminds me of Electrocompaniet's ECI-2, however, ECI-2 is a little more open, but also not quite as fast the the 551. Quid pro quo.


So, let's sum up. This is a small, neat and very tasteful package, a rarity these days. It will fit in almost anywhere and be in good company. It needs a remote to be able to work as conveniently as it can, but you have to pay extra for it - a moot point, both sides have equal odds at being right or wrong. Anyway, remember you'll need it if you're buying only the amp and don't hesitate.

You cannot open up the box because you need special tools to do that - possible reasons for this are many, like the need to go over the procedure in exact steps thus eiliminating the amateurs, or the desire of the manufacturer that you not see what's inside (in Meridian's case, I'd say this is the least likely reason), the desire to force you to use the appointed mechanic to service it, etc. Whatever it is, I don't like this approach, I never did and I never will, and I fault Meridian for taking this route, no matter what their reasons may nominally be.

Its sound is transparent and relaxed, well controlled, and perhaps a little too well controlled - in my view, it could do with a little more gusto. Yet, you can listen to it for days on end and never feel any listener fatigue, so common with lesser products. Its control of speakers is very good, but it seems not to like difficult loads with very loud performances. It will not be stressed in the usual manner, it will just abandon some of its sound quality in favor of power.

In my view, while this is a good unit, I feel that it's ultimately overpriced for what it offers. It's well made and therefore cannot be cheap, but I think that for less than this money, you can do better, or at least just as well, elsewhere (possible candidates could be NAD 317 new version, Pioneer's Precision amp, Harman/Kardon's HK 680, etc).

So, in a nutshell - good, but overpriced.

© 2000 Copyright Dejan Veselinovic - http://www.tnt-audio.com

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