The Musical Fidelity A1 was launched
in 1984, and its distinctive design attracted as much praise as it did
controversy. The electronic design was by Tim de
Paravincini. The amplifier remained in production until the early 90s.
Today, it is considered a classic.
The top cover is used as a heat sink and typically runs at 55-65°C - too hot to touch for more than a few seconds. This is caused by the output stage being biased with a standing current of around 800mA. If one applies standard class AB analysis, this results in the first 8 watts being delivered in class A - however, Tim argues that things are not quite that simple.
It does have a certain sound that has earned it praise over the years, but whether or not this can be attributed to class-A operation is open to debate. It is undeniably coloured - many reviews draw comparison with valved equipment.
Objectively, compared to its peers, the A1 has a generous power supply, uses some reasonable quality components and is quite well-made. Reliability is a thorny issue; there was no shortage of failures over the years. Facilities are minimal - you get an input selector and a volume control - apart from the power and tape-monitor switches, that's it. Well, apart from a phono stage that worked with MC as well as MM cartridges. But no other facilities were included - no tone or balance controls, no headphone socket or loudspeaker switching and don't even think about remote control - this was 1984!
You don't even get much of a manual for your money - a single sheet of A4 folded in half... Click on the thumbnails below to view...
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Model History
This section is sorely lacking as I only own one example! From old magazines and the promotional booklet that Musical Fidelity included in Hi-Fi News a few of years back, I've been able to put together the following:
The A1 was released in 1984 to rave reviews. Minor revisions occurred throughout its life - the earliest models didn't have ventilation holes in the side panels, and the top cover was in two sections. The power supply capacitors were axial (wire-ended) devices that laid flat across the PCB. There were also some component value changes over the the years. My 1990 example is regarded as a MKII, and has a one-piece cover, vented side panels, and radial power supply capacitors. I don't know if these changes were introduced together or at different times, and at what point in time each of those changes occured. You can see the differences on the next page.
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Opposite is an
extract from the 1990 brochure. The price is the sale-price that I paid -
normal retail price at the time (summer 1991) was £300.
Shortly after the MKII upgrade, the A1 was upgraded to Mark 3 status. This involved a minor power increase to 25 watts per channel, and several changes to the circuitry within. Reviews were as postive as ever.
There were a number of special editions over the years. In 1991 Musical Fidelity released the "Collectors Edition" - of which only 24 were made, apparently. In the same year, they also released the "Final Edition", another limited production (only 200). Please note that these dates were taken from the Musical Fidelity booklet referred to above, and seem slightly earlier than my recollections - of course it takes time for stock to move via the retail channels.
Both the Collectors Edition and the Final Edition had an external PSU, and the latter had an increased power output of 40 watts per channel. Amusingly, the Final Edition is actually a B200 - a completely different circuit with a MOS-FET output stage. Apart from the phono pre-amp, just about the only thing in common was the case!
In parts of Europe, the A1 was called the A1-X. I've been sent some pictures of this, and I can't really tell any differences apart from the model designation. Also, there was a version in Germany called the "David". This was a tuned version, apparently.
The "new" A1
In 2008 the A1 was re-launched, but this new model resembled the original in style only - electrically it is very different. The user interface is also radically altered, with electronic control of volume and input source selection - gone are the large rotary controls for those functions, replaced with small pushbuttons and a centrally mounted LCD alpha-numeric display module (Musical Fidelity used these a lot at the time, but I've always felt that they're not appropriate for a premium product, given their limited contrast and very poor viewing angles). Of course, there is a remote control - a "system" remote that can control other Musical Fidelity products, so it has a lot of buttons. A phono stage was provided, but MM only this time. Power output was quoted as 36 watts per channel, according to the user manual. And there is a USB DAC - that's a sign of the times!
This amplifier was joined by a CD player that used the same case, along with a preamplifier that used an outputboard power supply. However, none of these were in production for long - I'm not sure why, but perhaps sales didn't live up to expectations, or maybe it was always intended to be a limited production run. As even a casual observer will know, Musical Fidelity do seem to have a high "churn rate" in their product lines...
The "new new" A1
Musical Fidelity re-released the A1 again in 2023. This time, the amplifier looks much more like the original, with the same front panel layout, with two large rotary controls and two buttons.
The red power LED is now blue, which fits with the blue print on the front panel and their logo, but IMHO blue LEDs are a little passé these days - the world overdosed on them 25 years ago! In addition to the power LED above the power switch, the volume control and input selector knobs also get them.
This version gets remote control, but that's the only nod to modernity this time - there's no USB input nor any other digital options. There is a remote control, but it only has volume and mute funtions - compared to the 2008 version it is distinctly minimalist, which is no bad thing IMHO. The volume potentiometer is an Alps motorised type.
The tape monitor function has been removed, which isn't surprising in this day and age. The pushbutton that used to do that is now a pre-amp bypass button. Pressing this removes the pre-amp that is placed ahead of the volume control, reducing the overall gain of the amplifier by 10dB. I'll come back to this in a moment! Like the original but unlike the 2008 version, this one includes MC capability in the phono stage.
This time, Musical Fidelity are very vocal about the authenticity of this amplifier, stating they are using the same "circuits of the 1985 rendition". They then go on to say that "the pre-amplifier is the same as the original 1985 design". But this can't be true. As explained later, the original pre-amp is an active design which destroys the volume potentiometer because of DC currents passed through the wiper. But in the previous paragraph the operation of the Direct button was explained - everything written about this on the product page and in the user manual implies that there is a 10dB gain stage ahead of the volume control, which presumably is being used as a conventional potentiometer ahead of the power amplifier.
Of course, it's good that they chose not to use the original pre-amp, which was flawed in its design. But you can't can't claim to use the "original circuits" when you're not. It leaves me questioning the veracity of that claim elsewhere in the amplifier - are they really using the A1 circuit in the power stages, for example? From what I can see, it's quite possible, but I can't confirm nor deny that at this stage.
Shortly after writing that, I found an interview with the person responsible for this version of the amplifier - Simon Quarry - on the What Hi-Fi website. This confirms what I've concluded - he even concedes that the active pre-amp was indeed "problematic", though he only touches on the effect on channel balance rather than the DC problem (the relative tolerance of the resistance of the potentiometer tracks is not tightly specified, so a good design - active or conventional - will not use a dual potentiometer as a rheostat). He also states that the rest of the design is true to the original. And the width of the amplifier is increased to "standard" 440mm from the 408mm of the original, which should also help with cooling. Quotes because standard-width hi-fi gear is 430mm.
The power supply has been upgraded, using separate secondary windings for each channel, and I think I see a connection for an electrostatic screen. The unit is now Class 1, with a protective earth connection. The main PCB is a modern double-sided affair, using a blue solder-resist.
There are additional PCBs for the mains wiring, including the power switch; one holding loudspeaker muting relays; and also one between the front panel and the chassis for the remote control. I don't know if the mute function is acheived by those speaker relays or via some other means, but a review by Stereophile states that the mute function "operates on both the loudspeaker and preamplifier outputs", which means there must be some sort of muting circuit acting at line level. I can't seen any relays on the main PCB that could do that, so presumably they are using muting transistors.
I also don't know if there is DC detection to protect the loudspeakers from the amplifier failing - it looks like there could be some extra components on the relay board, including a couple of electrolytic capacitors that could be providing the necessary filtering, plus there's rather a lot of connections between that and the control PCB behind the front panel - 6 rather than the 2 you'd expect for just the relay coils - so it is quite possible. I haven't spotted any mention of this in the manual or on the website, but then few manufacturers make mention of it - while including DC fault protection is the responsible thing to do, no-one wants to draw the customer's attention to the possibility of such a catastrophic failure by stating there is protection in place for such an eventuality. And when that's combined with the poor reliability of the original amplifier, which is still common knowledge today, on balance it's probably best to say nothing...
There is also a review from Hi-Fi News, which includes test results from Paul Miller. They mention that the internal heat sink bracket is now secured to the chassis as well as the top panel, which presumably helps a little with heat sinking (while I assume the bottom panel is steel rather than aluminium, every little helps!). The original amplifier uses a U-section that is secured to the top panel with 3 M3 screws - no other mechanical connection is used. The TO3 output transistors were connected to the PCB via short wires; this version will use plastic transistors soldered directly to the PCB, so my working assumption was that the heat sink bracket would be mechanically attached to the PCB at the very least. I've yet to find a photograph that shows the detail of this, nor do I know what transistors are used.
Please note that I have deduced the above from information found on the product page, including the user manual, plus various reviews, including the ones cited above. Additionally, several pictures found online have been useful, including this one from the Hi-Fi News review. I have not seen one of these in the flesh, nor had the chance to audition one, so please regard this as a "desktop survey" - of course, if anyone wishes to lend me an example for an more in-depth - and quite possibly warranty-voiding - technical review, please do get in touch.
Despite my minor concerns about the claims of originality made in the marketing material, especially around the pre-amp stage, I am glad to see the return of the A1 in what appears to be a reasonable homage to the original, and will be interested to see how long it stays in production. I don't follow Musical Fidelity (nor the wider hi-fi market) closely these days, so honestly don't know if the product churn rate mentioned earlier is any different in the post-Michaelson era. But in the What Hi-Fi interview with Simon Quarry mentioned above, he speaks of how the new owner (Heinz Lichtenegger of Audio Tuning, the parent company of Pro-Ject) was keen to bring back the A1 for nostalgic reasons, and as it appears to have received nothing but positive reviews, it's likely here for a while yet.
Other models
There are a number of other Musical Fidelity amplifiers that are related to the A1 - more details later. In the meantime, the A1 is deconstructed on the next page...