Archive: McLaren A150B amplifier

The "little Mac"

By Charles Thomson

March 2005 (originally appeared October 1990)

McLaren A150B. $1599 in 1990

The original McLaren A150 integrated amplifier has been on the market now for nearly four years. In that time it has earned an enviable reputation for both performance and reliability.

When announcing a new product McLaren usually opt for a completely different model number, which certainly avoids confusion in a prospective purchasers mind. He/she knows that the new model will offer definite design and sound quality improvements over its predecessor.

What then should be expected of this "b" version of the A150? Minor cosmetic or circuit alterations, or a completely new product?

Unpacking the A150B immediately showed that the styling changes were not in the minor league. Wider, sleeker and to me, more elegant. The lack of any visible heatsinks also suggested that the amplifiers innards must have been reworked.

Measuring 432mm wide (an increase of 13mm) means that the A150B is now the same width as most other full size components and reduces the somewhat squat appearance of the previous model. While a reduction in size of the gold plated cap screws on the black front panel from 1/4" to 3/16" may seem small, it alters the visual look of the amplifier considerably for the better.

Other changes on the front panel include a two-colour LED power indicator (red while circuits are stabilizing after switch-on, yellow when operational) and repositioning of the rotary controls. Ergonomically this is an improvement for right-handed users, as the volume control, which is the most used control, is now located on the right hand side of the amplifier. Other rotary knobs are provided for balance, input and record selection. A headphone socket plus on/off switch complete the front panel.

So far my only negative reaction was that the silver colour of the headphone socket seemed out of place when surrounded by the gold McLaren logo, gold cap screws and gold lettering.

At first glance the rear panel seems fairly standard: two switches to select cartridge loading values of 47k ohms or 100 ohms and either moving coil or moving magnet cartridge. Eight pairs of gold plated phono sockets provide connections for phono, CD, tuner, aux, tape 1 and 2 - both play and record. Three pairs of binding posts allow speaker cables to be connected so that ones speakers are either switched off when a headphone jack is inserted in the front panel or not.

A delightful feature of the rear panel is that all labeling of switches and sockets are printed both the right way up and upside down. This means that when making connections to the amplifier while peering over the top it is easy to identify the correct socket etc. Conversely is one is able to get behind the amp, the second set of labeling is the right way up to be read.

Removing the top cover which is held in place by four machine thread hex bolts that locate into dunk nuts (no self-tappers to strip threads here), reveals typical McLaren attention to detail. There is one earth wire from this cover necessary because the bolts which fasten it pass through substantial grommet type washers which isolate the cover both mechanically and electrically.

The internal layout is very neat, superb PC board and quality components almost create a picture that makes one reluctant to replace the cover. Attention to detail is obvious with some features surprising to find in an amplifier at its asking price of $1599, such as separate earths for each channel of the phono inputs. Power transistors and their heat sink are tucked away at the bottom of the amplifier with cooling being effected in a novel manner. A tunnel formed in the chassis underneath allows cool air to be drawn over the heatsinks and the warm air to be dissipated through a concealed gap between the top cover and the rear panel. No mass of holes to spoil the appearance of this amplifier.

The power supply has not been neglected in the new design with the most obvious change being a slightly bigger toroidal transformer which has a higher VA rating. To quote designer Bruce Crothers, "From a technical point of view, everything is better - THD, slew rate and noise. All the things that you see on the test bench have improved."

Involving and dynamic sound

Initially the A150B was connected to a pair of Tannoy E11 loudspeakers and immediately from switch-on produced an involving, dynamic sound. This amplifier, brand new and straight from the box, proved to require no running-in period. After approximately 30minutes of use the treble appeared to "sweeten" ever so slightly. This was not a dramatic improvement, quite subtle in fact. The same thing happened each time the amplifier was used from cold.

All this was a pleasant change from some amplifiers which require to be left on for several days to start producing of their best and even then requiring an hour or so to warm up after each switch on before serious listening can commence. Personally I would leave the A150B switched on all the time, but for those who prefer to turn their equipment off, they would not be bothered by sound quality that is not up to this amplifiers potential during a warm-up period.

During the first listening session I had the feeling that I had heard this amplifier before. Not that it sounded like the original A150, but the feeling persisted. There was something about the tonal balance that was familiar.

Going back over my notes of previous reviews and listening sessions suggested to me that1 was listening to a McLaren 03 series sound. Direct comparison with a McLaren 603 pre and 903 monoblock power amps showed that this was indeed the case.

Similar tight, rhythmic bass, well defined midrange, no excessive sibilance, good portrayal of solo voices and small groups, slight blurring of detail on massed choirs, well controlled and detailed treble etc.

The 603/903 combination certainly had advantages over the A150B particularly in areas of soundstaging width and depth, the sense of "air" around instruments, greater sense of presence and more effortless sound when coupled to more demanding speakers. All the things one would expect from separate pre/power components, separate power supplies and three times the price.

Compared to the original

Compared to the original A150, the "b" proved itself able to handle a wide range of speakers. While the quoted output is similar in both models (75 watts) the "b" seems more powerful. In fact it was much more at home with the JBL L80T than its predecessor, which struggled to reproduce a kick-drum or go particularly loud when coupled to this speaker.

Driving my own Magneplanar MG3 speakers was well within the capabilities of the A150B. Maybe not as transparent and spacious as I am used to with my Audio Research, but certainly involving. The original A150 struggled with the MG3's.

Using speakers more in keeping with its price range, such as Epos and Rogers LS4a's allowed the "b" to perform up to its potential. It didn't matter what kind of music was being played, rock, jazz or classical, solo performers or symphony orchestra. It was a musical experience.

Worthy of special mention is the phono input on the A150B. It would rank among the best I have heard from an integrated amplifier. Some may argue in favour of the Naim Nait or Creek 4140, and personal preference may lean towards the transparency and sense of rhythm these amplifiers can display. However the McLaren is a worthy competitor in these areas and its extra power and a greater sense of authority will make it the choice of many.

Using the A150B is a pleasure. All controls have a positive quality feel about them. Switching is provided for just about every possible user requirement and adequate inputs allow for connection of most likely components to be found in a home system.

Some readers may feel disappointed that lengthy details about the sound quality of various aspects of the audio spectrum as heard on certain recordings are not reported in this review. I feel that the A150b does just about everything right when compared to its price tag, and my advice would be to go to ones audio dealer armed with favourite music and have a listen. If the McLaren is not for you, rest assured that you would be paying considerably more for an amplifier that is.

Bruce Crothers discusses the A150B

What was your design aim with the A150B?

Generally you could summarise it as a general improvement in both sonics and in technical qualities of the amplifier. Particularly the sonic area, as we had some complaints from customers in Europe about the sound quality of the A150. Fairly vague and general complaints such as "it doesn't sound any good", which doesn't tell you a lot. But it certainly gave us a prompt. It told us that we had to do something about the amplifier. Also, the sales were falling away for the A150.

We sat down and thought about it and decided that we had circuits available to do much better sonically and technically. And that it was worthwhile implementing them.

Is a phono stage important today in an integrated amplifier in general, and specifically with the A150B?

I feel that its importance is reduced in general terms. On the other hand there are still people who are quite keen to run high quality phono setups, and I still see it as being important. It definitely has been considered in the deign of the A150B.

There was a reduction I manufacturing costs required in the phono stage, but we've made no compromise in terms of sonics or performance. In fact we've made considerable improvements in that area.

Most of the improvement in the phono performance has come from a very major improvement in the line level performance of the amplifier. Everything that comes out of the phono stage of the amplifier then has to be processed by the line stage. Any improvement there will also improve the quality of the phono stage.

The original A150 had line inputs going directly into a high gain power amplifier stage, which used an IC (integrated circuit) as a major part of its circuit. What has changed with the B and why?

We moved away from the IC because we wanted to implement the 03 circuitry into the power amp stage because the sonic performance is far superior. It's been a bit of a juggling act in terms of costs, in that we have shifted the emphasis in cost terms from the phono stage to the power/line stage.

The philosophy of the first A150 has been kept in that it is still a high gain power stage and all of your high level inputs run directly into that stage without a specific line stage before it. I think that it's an exciting high level stage in that there are virtually no compromises made in its design. It's definitely a very high quality power amp and it has the huge advantage of not having a line stage, sonically it's of very high quality.

The power supply is very important to any amplifier. Normally there are a couple of large power supply capacitors bolted to the chassis and wired into the circuit board. Your design uses ten smaller capacitors directly on the board. Why did you use this approach?

It's a follow on from the A150, where that technique was used successfully. The technical and cost analysis that I did for the A150 still holds. Ten smaller capacitors gives you a slightly higher performance capacitor and a somewhat reduced cost, particularly in terms of installation. Bolting down capacitors and wiring to them is quite an expensive exercise. Being able to drop them straight into the board saves quit a lot of money.

The major advantage of using multiple smaller capacitors   is lower series resistance. That means that there is a slight reduction in power supply noise and a slight increase in the amount of current throughput that the power supply can handle. The overall result is an improvement in the sonics of the amplifier.

I'd also like to mention the power supply stages for the lower voltage stages of the phono input and power line stage. The predriver stages of the power amp and the phono stages are both on regulated power supplies - that's pretty normal these days.

Preceding that, another regulated power supply gives you mostly noise isolation from the main unsmoothed supply which runs the output devices. That has a very significant impact on the sonic qualities of the amplifier.