TFPRO E82 (replacing the TFPRO P9) Now in Development

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The TFPRO E82 is a dual channel fully switched precision mastering equaliser with 5 stages of response tailoring and level control, in 2U rack mount form.

TFPRO E82

E82 Front panel design draft

It is designed primarily for detail sound correction of precise frequencies with particular attention to response extremes and is assembled and tested in the UK.

The new E82 EQ joins the original P9 in offering exceptional sound quality; a sound that can be described as ‘luxurious’ and with unbreakable headroom.

INPUT STAGE

The line level XLR and jack input goes via a balanced transformer with an input impedance of 10Kohms designed to operate at a level between -10dBu and +8dBu and with a flat response from 8Hz to above 25KHz . The unique design of input circuit eliminates low frequency distortion and retains flat response far beyond digital equipment.

THE EQUALISER

The EQ sections operate in frequency bands that that are important to musicality; this EQ brings together the physics of sound reproduction and ‘what sounds right’, it is a harmony of experience and careful design.

LF SECTION

This is an inductor-based equaliser with switchable ‘shelf’ or ‘peak’ response. Frequencies covered are 20Hz to 125Hz in 6 steps with switching lift and cut in 23 steps with 0.5dB resolution from -15 to +15dB. Care must be taken as lifts of extreme low frequencies are possible. Alteration of sub-sonic balance has a profound effect on the spaciousness of sound.

MF1 SECTION

This is similarly inductor based but with switchable ‘sharp’ and ‘broad’ resolution. Frequencies covered are 125Hz to 700Hz in 6 steps with switching lift and cut in 23 steps. With small amplitude changes the phase shifts in the music are kept under control producing a harmonious sound.

MF2 SECTION

This is also inductor based with switchable ‘sharp’ and ‘broad’ resolution. Frequencies covered are 700Hz to 4KHz in 6 steps with switching lift and cut in 23 steps. These frequencies are normally thought of as ‘high’ and must be treated carefully to retain smooth sounds, the ear is most sensitive to these frequencies. Small lifts and cuts affect the apparent ‘depth’ of sound.

HF SECTION

This is ‘Baxandall’ type with shelving response. Frequencies at 3dB down, 2.8KHz to 12KHz with switching lift and cut in 23 steps. The HF section is used to control the clarity of the sound without affecting depth too much.

AIR BAND SECTION (extreme HF)

This is capacitor based with shelving response. Frequency at 3dB down, 16KHz with lift and cut from -8dB to +8dB in single sweep. The purpose of adjustable ‘air-band’ is to introduce or control the extreme high frequencies; what we used to call the ‘fairy dust’.

HIGH PASS FILTER

12dB/8ve switchable filter at 25, 50 and 100Hz. This is a safety feature to minimise danger to monitor loudspeakers! The EQ is not for beginners to play with and is capable of extreme performance changes in both low and high frequencies.

GAIN SETTING STAGE

Switched gain adjustment from -15dB to +15dB in 12 steps to set the correct audio level and allow room for volume level adjustment.

METERING

A precision LED meter shows peak levels in 8 steps up to +12dBu with a separate ‘overload’ indicator operating at +18dBu.

An IN/OUT by-pass switch bypasses the 5 EQ stages but maintains the set gain setting and filter setting.

OUTPUTS

A low noise output stage provides floating balanced outputs via XLR and standard jack. Additionally, digital output at 96KHz 24 bit appears on USB.

POWER

The E82 is mains powered with an internal supply working at any mains voltage.

STATUS

Development is not yet complete although all circuitry has been built and tested with excellent results. After studio testing the aim is to see a product release towards the end of the summer 2021.

2 Comments. Leave new

  • Ted Fletcher
    March 6, 2021 5:57 pm

    I’m very familiar with M/S systems going back as far as the 1960s with the elliptical equalizers in the Neumann cutting lathes.
    More recently I have studied and experimented with the effects of M/S circuitry in loudspeaker development with exciting results; a work that is being continued by my son Daniel.
    I’m more cynical about trying to implement frequency limited M/S systems in equalisers as the results can be unpredictable and such things are generally much easier to achieve in the digital domain.
    I try to stick to areas where analogue circuitry is a significant advantage and where small changes are unlikely to produce disasters. However, these comments are interesting and I shall certainly consider introducing some M/S facility in the LF section, and possibly some ‘width’ control in the upper mids.

    Reply
  • Alan Watters
    March 6, 2021 12:15 pm

    Hello Mr Fletcher,

    I am a longtime fan but this is my first time posting. Very much interested in this mastering EQ but I have a question on customisation.

    Would it be at all possible to add a mid side matrix to the LF and MF1 bands? It would be pretty nice to have this EQ close to the end of my chain and the ability to put the lower frequencies in mono would be very useful and would allow me to avoid doing this in the digital realm.

    The same could be said for the upper frequencies using the EQ to expand the sides but I don’t know if this would add an exorbitant amount in terms of pricing afterwards?

    I hope this finds you well,

    With Best regards,

    Alan.

    Reply

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