The first professional review of the Music First Audio Ref. MM Phono Amplifer can now be downloaded and read on the HiFiPig website.
Designed to be the best MM phono stage with no compromise performance. Used with a SUT for optimum effect. A demo unit is now available to audition. Please enquire if you are serious about extracting as much of the information in those vinyl grooves as possible!
Why use a step up transformer, please see why at the bottom of this page ###
The Music First Audio reference MM phono pre-amplifier has been 10 years in the making, it is designed to give the best possible sound quality from vinyl. Used with a MF Audio step up transformer or any high end SUT the music will be so life like it will reach out and touch you. We are writing from experience having heard this phono stage in action, it really is set to become a landmark product.
Music First Audio’s new Reference MM Phono Stage is a high end, premium priced valve phono pre-amplifier. The result of years of development, it combines vacuum tube and solid state circuit topology to bring the beauty of valve sound with the long term stability that transistors afford.
The front end of the Reference MM Stage employs a very low noise pentode originally designed for the demanding European communication industry, combined with a dual triode to provide the ideal characteristics of high gain, low noise and low impedance drive.
This first stage, then drives an inductive equalisation network showcasing Music First Audio’s many years of coil winding expertise. The accurately equalised signal is then amplified and passed through Longdog Audio’s signature line driving stage. Power for the dual mono circuitry is provided by an isolated and regulated power supply which feeds, via high quality locking connectors, four discrete high voltage, low noise regulators that power the active circuitry.
The Reference Phono Stage is housed in superlative quality non-ferrous aluminium casework and is designed and built exclusively in the United Kingdom. The result is a phono pre-amplifier of exceptionally high ability, offering unparalleled transparency, harmonic accuracy and reliability.
Some notes from the designer of the phono amplifier……………………………
The Music First Reference Phono Amplifier is an all valve moving magnet phone stage, employing innovative (possibly unique) circuit design, careful component selection and LCR RIAA equalisation.
Whilst on paper, the requirements for a phono amplifier are simple, in practice, they are far from it.
We start with a signal from the cartridge or step up transformer of only 1mv, then apply enough gain to convert that to a line level signal while at the same time applying a accurate RIAA equalisation curve. while at the same time providing a low impedance drive to the following system. Firstly, the 1mv signal. If we want to aim for the best signal to noise ratio, we need to look at at least 80dB S/N here. For a 1mv signal, then that means the noise needs to be below 100nv (0.0000001v). But it goes further that that, the RIAA curve means that the low frequencies will be 20dB (10 times) lower. That means we are looking for an input stage that can give us a 100dB S/N ratio, we are down to 10nV. But to prevent surface noise, clicks and pops from affecting the sound, we need a stage that will not be disturbed by these impulse signals. The reason why many phono stages seem to make records sound noisier than other is down to how well (or not) they handle these signals. This is one of the reasons why valve phono stages can often be better sounding than solid state ones, the power rails of a typical valve phono stage are in the 250v area, this gives far more headroom than the typical 18v supply in a solid state unit. So, we need to handle impulses which can be up to 40dB (100 times) above the normal level. So we need a front end that can handle signals from 100mv to below 10nv, a 140dB S/N ratio. Not a simple task.
To provide the huge dynamic range required of a signal from a cartridge we use an innovative circuit that makes use of the best of the valve and solid state world in conjunction. An ultra low noise pentode (D3a) from when the last days of valve technology, was at its peak, is used. This combined with an active load and output buffer with self adjusting stabilisation circuity means that super low noise, low distortion (good as most solid state designs), wide bandwidth (DC to over 1Mhz), high slew rate (can swing 60v at 300kHz), stability from component ageing and large overload margins makes it the ideal front end for any phono stage.
Once we have amplified the delicate signal from the cartridge, we now have to apply the RIAA equalisation. While many designs split this EQ over two or more stages, or use it as part of a feedback loop. We believe that the best sounding RIAA is done in a single stage, using no overall feedback loops. Further to that we believe the best sounding RIAA can only be achieved by the use of a LCR T-Network. Unlike most RIAA stages that employ just resistors and capacitors an LCR design adds carefully chosen inductors to the mix. By the addition of these inductors, it becomes possible to create a network that provides the accurate equalisation needed, while also (and most importantly) provide a fixed impedance load to the driving stage. It is this constant impedance characteristic that allows LCR based phono stages to produce the uniquely realistic and transparent midrange and detailed bass response that only they can achieve.
While the LCR network provides an idea solution, driving it from the preceding stage has often been the problem area in previous designs. In the case, the innovative first stage we have already described, provides the ideal solution to driving the LCR network.
Once our precious signal has been through the LCR network, its up to 100 times smaller than before. So we again need to amplify it and make it ready to drive the following system. Now we use one of the best sounding 9 pin valves, the 6072a dual triode, we use this valve for the same reason many other top designers use it, it provides good gain, low noise, and good sounds. In this case its used in a active load (SRPP) configuration. This stage then feeds an output buffer. We use a 5687 triode for this job. This is just one of the best output buffers around, and we make no apologies in using it once more in this design.
So, that’s the amplification part of the design, but anyone who knows our previous award winning products will know that at least 50% of the sound of any design is down to the quality of the power supply (well, maybe 75%). So we have not skimped in this area. Each channel board in the phono stage contains two independent low noise high voltage shunt regulators to provide the cleanest, quietest power to the circuit. We don’t forget the heater supply either. Two stages of heater supply regulation is provided on each phono board, each with a dedicated supply for the input valve.
Given that we are dealing with such minute signals, it would be foolish to put all this circuity next to the mains transformer (and the box would have to be huge, as it is, its full). So we have made this a two box design. Not wishing to allow any noise into the phono casework, the power supply contains first stage high voltage and heater regulation, reducing the power rail noise and ripple to the sort of levels that would normally be accepted for many traditional designs, but here is just the input to the primary regulators.
To connect the two boxes, we use industrial connectors designed for the purpose, with voltage and current ratings that exceed what is needed here, so will provide long lasting service. The casework of the two boxes are non magnetic to avoid interaction with the circuit, while providing shielding for the precious signal. All the components are chosen with their sonic characteristic as well as their electrical suitability. Charcroft Z Foil resistors provides the cartridge loading, and Takman carbon and metal film resistors are used through the signal circuity. Elna electrolytic and Mundorf film capacitors are used throughout the circuitry.
Two Box LCR Valve Reference Phono Amplifier:
Valve line up:
D3a * 2
6072a * 2
5687 * 2
Input sensitivity 1mv at 1kHz
EQ: Within +- 0.1dB 30-20kHz
Input impedance 47k + 75pF (designed for MM, high and medium output MC and low output MC with a step up transformer).
Overload margin 300mv at 1Khz
Power consumption 100W
The Music First Ref. MM Phono Stage is supplied in 120V or 230V versions with an IsoTek power cable to suit your country, standard warranty is 2 years.
### The Music First MM Phono Amplifier is designed to be a no compromise design to be used with a step up trasnformer, why use a SUT.
Why use a separate moving coil step up transformer?
This is two questions in one, the first is why use a step up transformer (SUT) and if using one, why its better to have it separate and not built into the phono amplifier.
The first question: Why use a SUT?
There are two good reasons why a properly constructed SUT is the best way of listening to a low output moving coil cartridge. The first one is distortion (well, so is the second, but not so obviously). Both a solid state gain stage and a SUT will introduce distortion to the tiny signal, but its the nature of that distortion that is important. A transformer will distort most at low frequencies, becoming increasingly perfect as the frequency increases. By the time the all important mid range of frequencies are reached, the level of distortion is vanishingly small (approaching the mythical straight wire. Because it is basically just that, a wire). A transistor gain stage on the other hand will have a lower level of distortion at low frequencies than a SUT, but that distortion level will stay constant as frequency increases, so by the time the all important mid range is reached, the transistor gain stage will be audibly distorting the signal whereas the SUT will be completely clean. The difference is easy to hear, even the best solid state device will sound edgy and grainy, whereas the SUT will sound like nothing, it will just let the music through.
The second reason is similar to the first, but relates to the rest of the phono amplifier. There is no point is dodging the truth here. A good valve phono stage will sound better than a good solid state phono stage, and a great valve phono stage will sound better than anything else (we are ignoring the bad examples that are out there of both types, the fact that you are on this web site shows that you are only interested in the best). By its nature a valve phono stage is that its at its best with the signal level of a typical moving magnet cartridge, so to get the best from a valve phono stage with a low output moving coil cartridge (considering the previous facts about distortion) the best solution is to use a SUT.
The second question: Why use a separate SUT?
Well, its perfectly possible to build the SUT in the same casework as the phono stage. But to do so we either limit the size of the step up transformer or we have a huge phono stage. Small step up transformers can be made, but remember the discussion about distortion and low frequencies? Well, the solution to get that distortion as low as possible even at low frequencies is to use as large a core to the transformer as possible (there are limits, beyond a certain size other problems start to be introduced). While its possible to make a SUT smaller than the size of a box of matches, doing so will severely limit the potential performance. At Music First Audio, we know that a large core gives audibly better results. So that is what we make. And that is why we make it in its own casework.
Review of MFA Reference MM Phono Amplifier
I should declare from the outset that I am a fan of Music First Audio hi fi equipment and so I viewed the prospect of trying out the new Reference MM Phono Amplifier with great anticipation. Whilst the MFA is described a Moving Magnet Phono Amplifier it is not really intended for use with moving magnet cartridges. The MM simply refers to the fact that it will accept the voltages (c.5mv) normally associated with moving magnet cartridges. In reality its partners are more likely to be a low output moving coil cartridge and high quality Step Up Transformer (SUT).
For this review I used it with a Denon DL-S1 MC cartridge (output 0.15mv) and Music First Classic SUT.
The recordings I selected were:
1. Poulenc – Gloria / French National Radio Orchestra & Chorus / Georges Pretre on HMV 1961
2. Holst, Handel & Bach / Cleveland Symphonic Winds / Frederick Fennel / Telarc 1978
3. My Fair Lady / Film Soundtrack Recording / CBS 1964
4. Gerry Mulligan Meets Scott Hamilton / Mobile Fidelity Soundlab 1986
There was no particular rationale for their selection apart from the fact that they were readily to hand and with the exception of the MOFI were all normal commercial recordings. I feel you sometimes learn more about the performance of equipment when playing commercial recordings that are less than perfect particularly in the way that it handles the imperfections, than you do by playing audiophile recordings of consistently high quality.I like to listen at concert hall levels in my music room so with vinyl replay low intrinsic circuit noise is essential. The first thing that was apparent with the MFA was that it was vanishingly quiet in use leaving the music to shine through unimpeded.
I was struck by the fact that the sound had a remarkable tonal accuracy, transparency and naturalness. Instruments existed in a real acoustic which gave a three dimensional effect to the sound. It opened up performances making them thoroughly involving. Dynamic contrasts were most impressive with the MFA able to move from the merest whisper of sound to huge crescendos of orchestra and chorus with total control. I found myself being pulled into the music and had to consciously force myself to step back in order to analyse what I was hearing.
The Telarc recording can sound a bit sharp and edgy on some systems. With the MFA woodwinds were smooth and silky, trombones and tubas had genuine rasp, presence and weight, likewise trumpets had precision and power. Cymbals shimmered. The soundstage was very large with real width depth and height. It was as impressive in very soft passages of music as it was when playing very loudly which is not always the case.On the Poulenc Gloria the choral sound was beautifully sweet and airy and the MFA showed a remarkable ability to cut through the densest of musical textures. Given the long reverberation of the church of St Etienne du Mont, Paris in which it was recorded this was no mean achievement. Rosanna Carteri’s solo parts were beautifully presented.
The MFA was very strong in the midrange presence region giving crystal clarity and transparency without ever becoming hard or strident. This is a very old recording with some surface noise and some obvious tape editing but the MFA seemed be able to deal with the imperfections and set them aside. The MOFI recording sounded very pleasing and beautiful. The saxophones of Gerry Mulligan and Scott Hamilton had a real swing and presence and I felt that I could reach out and touch the players. Previously this record could sound a little harsh and the saxophones a bit too woody and stark. Not here. On the MFA they were presented in a highly detailed and smooth fashion.The My Fair Lady soundtrack recording also was handled impressively.
The original recording is not as good as some and is showing its age now. Once again as with the Poulenc the MFA managed to overcome the obvious defects and somehow convey the essence of the music.All in all I found the MFA Reference MM Phono Stage a sonic gem and a complete delight. At nearly £10k it is expensive but if your pockets are deep enough and you have a good enough system in which to accommodate it this unit will give many hours of listening pleasure. It could be the last phono stage you will ever buy.