Phono Amplifiers

Welcome to the Music First Audio Phono Amplifier page

Email for a home demonstration

2 models of Phono Amplifier are available

Classic Phono Amplifier 632 March 2015 – present

Reference Phono Amplifier February 2015 – present.


 

Classic Phono Amplifier 632

“Music First Audio has another winner on its hands” Adam Smith HiFi News May 2016.

 

 

MF-632-step-up-&-phono
Phono amp 632 with step up transformer 632.

 

 

 

 

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XLR and RCA outputs. RCA inputs. Grounding post and 3 position ground lift switch.

 

Priced at £2100 GBP plus VAT if applicable

Priced at $2730 USD plus local taxes.

This new product is now available for shipping. Using an external +/- 18 v power supply. Using a pair of mu-metal cored output transformers to give both RCA and XLR outputs. The transformers with a 3:2 step down ratio enable the output to drive longer cable than a conventional phono amp. The use of high quality components throughout give a magnificent performance.

Music First Audio
Available in many front panel colors.

Music First Audio Dual Mono MM Phono Amplifier
Technical description:
Two identical boards each with it’s own power supply and amplification circuitry making the amplifier a true ‘Dual Mono’ unit.
An external power supply provides a +/- 18V AC voltage. There is a bridge rectifier comprising of 4 discrete ultra fast soft recovery diodes, a bank of audiophile quality Elna Silmic electrolytic capacitors and two high performance low noise voltage regulator circuits.

The main amplifier circuits comprise two active gain stages with passive RIAA equalisation. Each amplifier stage is biased into ‘class A’ with the use of constant current diodes. Mundorf ‘M-Cap Supreme’ capacitors and low noise metal film resistors are used as the main elements in the RIAA stage. High quality Polyproylene decoupling capacitors are use throughout.
The output transformers are each driven by a THAT1646 balanced line driver. Radio frequency noise is minimised by a filter between the THAT chips and the transformers.

 

Available with both XLR and RCA outputs as standard. RCA input as standard. XLR input available on request.

Designed, and manufactured in the UK, from a company with a family phonograph heritage going back to 1949.

Available at £2100.00 GBP plus VAT. Please contact Mr Billington for more information on a purchase or a home demonstration


 

Reference Phono Amplifier

HiFi Critic April – June 2017.  Read the Andrew Harrison review of the Reference Phono Amplifier. Click Pages from Vol 11 no1 MFA Reference phono amplifier to down load the PDF.

HiFi_Critic_award

 

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.

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Priced at £8200GBP plus VAT if applicable.

Priced at $10660 USD plus local taxes.

“… The separate power supply helps reduce noise…”

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“…frees up a wealth of detail…Providing a new sense of realism…OUTSTANDING- amongst the best…”

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!

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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 a 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 handles 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. A ultra low noise pentode (D3a) from the last days of valve technology was at 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 design), wide bandwidth (DC to over 1Mhz), high slew rate (can swing 60v at 300kHz), stability from component aging 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 look. 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 achived by the use of a LCR T-Network. Unlike most RIAA stages that employ just resistors and capacitors a 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 achive.
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 boards, 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

Gain 52dB

Input impedance 47k + 75pF (designed for MM, high and medium output MC and low output MC with a stepup transformer).

Overload margin 300mv at 1Khz

Power consumption 100W