All MTR products are made in England

HPA-6                                                                                         Headphone Amplifier

 Photo MTR HPA-6 headphone amplifierPerhaps the most high powered and reliable headphone amp available.  There are two separate main stereo inputs on ¼" jacks, plus a stereo Auxiliary input feeding stations 1 and 2 (or any combination of all six by simple internal re-wiring).  This Auxiliary signal is added to the main inputs, and can be used for click tracks, talkback from the control room for more effective communication between the engineer/producer and musicians, or silent rehearsing to an mp3 player/CD, etc.  A two-colour led is fitted to each of the three inputs, showing green for signal present, and red when approaching input overload.   The Main Input 2 also has bass and treble boost and cut.  Each of the 6 headphone outputs has its own volume control, an input 1 or 2 selector button, and a mono switch sums the left and right signals.  The rear panel has duplicate input sockets for easy rackmounting.  Very solid all-steel construction, and volume is more than ample with headphones ranging from 8 to 2,000 ohms.

A,B & Aux Input Imp:  20Kohms unbalanced stereo     
A,B & Aux input sensitivity:   0.25 volts nominal
Max Output:   2v, 500mW into 8 ohms - 4.7v, 35mW into 600 ohms - 4.8v, 10mW into 2,000 ohms    High / Low e.q: 10kHz / 100Hz ± 13dB.   System Gain: 28dB, e.q. flat.   Hum & Noise: -85dB unweighted.    T.H.D.:  0.07% @ 1KHz    Freq. Response:   10Hz-20kHz ± 3dB   Max Consumption:  100mA    Dimensions:  44x483x205 mm     Weight: 4 Kilos

Link to MTR HPA-6 headphone amplifier press review

HPA-2_____________________________________________________2 Channel Headphone Amp

Photo MTR HPA-2 Headphone AmplifierDerived from our HPA-6 model, this smaller stand-alone version has one stereo input and one Aux. input on ¼" jacks, a Loudness button, and two headphone outputs, each with a volume control and a mono button. It is mains powered, with a rear panel on/off switch and fuse.

Multiple units can be scattered around the studio, and the Aux. input allows the electronic musician to set his own level relative to the foldback. Also used by club DJ’s with mixers having an inadequate headphone amp.

Specifications are as the HPA-6 except the Loudness button, which gives 6dB boost at 160Hz and 10kHz. Weight: 2 kilos. Dimensions: 225mm wide, 162mm deep, 70mm high.  As used by the BBC, Associated Press Television News, Television Systems Ltd (ITV Anglia, Tyne Tees, ITV West (Bristol), etc.

"If you only need 2 pairs (as I do) the MTR HPA-2 is a superb piece of gear - if you need more, they do a similar 6-way 1u rack box. This gear is bombproof and sounds great - and works with pretty much any headphones and you will get oodles (?) of level".  Phil Leigh, SOS, 10.3.01


SPA 200/400b                                                                                   Power Amplifiers

Two high quality power amplifiers offering 100, and 200 watts RMS per channel.  Both have peak led's warning of possible overload, mono bridging which doubles the RMS power in mono, a ground lift to eliminate hum loops, plus full thermal and open/short circuit protection.
The 1u SPA 200 has an all-aluminium chassis (no fans, so ideal for control room monitoring), jacks in and out, and twin torroid transformers.  The SPA 400b gives 200 watts per channel, still in a 1u package, and features soft start, very quiet twin cooling fans, balanced XLR inputs, Speakon and XLR outputs, and DC protection.
Photo MTR Power Amplifiers

  Specifications:       SPA 200
  Input Imp./Sens:   47 ohms / 0.8v RMS
  Power Output:       100w RMS per chan, 4 ohms
                             200 RMS Mono Bridge, 8 ohms
  Freq. Response:    20Hz-20kHz ± 1dB
  T.H.D & I.M:         0.01% full power, 4 ohms
  Hum & Noise:       -90dB unweighted
  Slew Rate:           150v/µS
  Damping:             Better than 300, 4 ohms @ 100Hz
  Separation:           -104dB @ 1KHz
  Dimensions:         483x44x280/483x133x346 mm
  Weight:                6.5Kg

  Specifications, SPA-400b:    As above, except:
Power Output:  200w RMS per channel, 4 ohms.     DC Protection:  ± 4 volts     Soft Start:  approx. 2 sec.    Thermal Cut:  95°.    DC fuses:   10 amp internal.   Dimensions:  483x44x305 mm.   Weight:  9Kg 

Link to Press Review of MTR SPA-400b amplifier


PPS-48____________________________________________4 Channel 48v Phantom Power Supply

Photo MTR PPS-48 phantom power supplyWith a built-in Mains power supply (no 'wall-wort'), this British designed and made unit offers 4 channels of rock-solid 48 volt phantom power, a ‘phantom present’ led and a rear panel ground lift.  With it's superb build quality, reliability and transparent operation - at the most critical stage of the audio chain - it is without doubt the best value for money phantom power supply available.  See also the PPS-248 below.

Inputs: Balanced XLR 48v Pins 2&3.
Outputs: Balanced Male XLR.
Input Level: 500mV max.
Freq. Res: 20Hz-25kHz ±1.5dB.
Fuse: Internal 100mA.
Weight: 1.3Kg net.
Dimensions: 260x110x48mm.

PPS-248___________________________________________2 Channel 48v Phantom Power Supply

Responding to requests, MTR now offers a two channel version, the PPS-248, also mains powered and with the same rock solid and ultra quiet 48v, housed in a smaller RF screened heavy gauge steel box.

Perfect for all those older, well loved desks out there without phantom power, for one or two condenser mics in computer project studios, schools, houses of worship, etc.

Specifications are as the PPS-48 above except two channels, dimensions are 172 x 130 x 45mm, net weight is 1.1Kg.  Minimum 25 pieces.




DC-8DUAL and DC-412______________          ________________Multi-Way Power Supplies

MTR DC-8DUAL keyboard power supplyFor multi-keyboard players, teaching schools, music classrooms etc., the DC-8DUAL is a safe, solid and reliable British-made unit with eight 9v DC outputs for powering Yamaha or Casio keyboards. A current rating of 4.2 amps ensures there is ample power to drive big keyboard

This unit comes factory-set to Yamaha polarity, but can easily be changed to suit Casio keyboards either by our warehouse (free of charge) prior to dispatch - please request this at the time of ordering - or by the user.  A dual colour red/green led confirms the polarity setting. Should a fault occur, an ‘overload’ led will illuminate, and a safety cut-out will shut down the unit: re-setting is automatic.  Includes eight x 3 metre DC-DC leads for Yamaha keyboards.

    Please note:  Casio keyboards using the AD-5 power supply have a different size DC     socket.     Leads are available for these keyboards at an additional charge, please specify when ordering.

If the DUAL is to be used with the new 32 key Casio SA-47 keyboards, they too will need special DC leads.  Note that Casio are using the Yamaha polarity on these particular keyboards.  The Casio adapter is the AD-95.

We can supply replacement leads for this range at an additional charge if needed, or include them with new purchases - please specify when ordering.

MTR DC-412 hi current 4 way keyboard power supply


The DC-412 has been designed to cope with large keyboards with disc drives and large LCD screens, that require a higher current and voltage.  Each of the four outputs provides 1 amp of current at 12v DC, and the unit comes complete with four 3 metre DC leads and the same current-sensing safety protection as the other models.

For schools particularily, these two products offer a far safer, more reliable and robust alternative to 8 separate "Wall-Worts" (which often don't pass OFSTEAD inspections), remove the need - and cost - of two 4-way plugboards, and the reduction in wiring means less Health and Safety issues.  Environmentally superior, and easily fixed 'in situ' for security.

Dimensions (both models): 190x135x75mm. Nett Weight: 2.9Kg     Minimum 25 pcs.


DI-3 & DI-2_________________________Active Direct Injection Boxes/Signal Splitter (DI-2)

Photo MTR DI-3 active DI box Quality direct boxes are hard to find in today's disposable marketplace - either quality products are too expensive or the economy version is too fragile.  The excellent quality DI-3 single channel D.I. box has a mono jack input and link out socket, a ground lift to eliminate hum loops, a three position attenuator for accurate level matching, and a balanced 600 ohm XLR output. The active electronics have a purely resistive high input impedance, and so do not colour the sound.  Both models can be powered in 3 ways: by a 9 volt battery, phantom power from the desk (or an MTR PPS-48), or an external 9v regulated power supply.

Photo MTR DI-2 active 2 channel DI boxThe DI-2 is a two channel version in the same sized box, for use with stereo keyboards or two separate mono signals. It can also be used as a balanced signal splitter by connecting a short jack-to-jack lead from the link socket of channel 1 to the input of channel 2.  Channel 1's signal will then be available on both balanced XLR's, and channel 2's link socket.  The attenuation switches remain working independently.

  Specifications -
  Freq. Res: 20Hz-20kHz ±3dB.
  Distortion: (THD) < 0.005% at 1kHz, 0dBu
  Output Noise: <-100dB unweighted
  In/Link Impedance: 1MOhm, jack.
  Output Impedance: 600 Ohms balanced XLR.
  Atten. Switch: -40, -20, 0dB.
  Ground Switch: Lifted/connected.
  DC Input: 9vDC, 100mA, neg. centre pin
  Phantom Power: +18 volts DC to +48 volts DC
  ‘Low Bat’ led: glows @ approx. 6v
  Weight: 0.5Kg

"I have a number of the MTR active DI's, and the newest of them has given over 6 years trouble free service - the oldest is nearer 20" - Peter John Chivers

"Another happy user of MTR active DIs. Note these DIs do not have transformers in them, so they have an interesting set of tradeoffs; they have extended frequency response compared to lesser transformer equipped DIs, so bass gtr is not a problem. It also means they never truly ground lift, and it means they never get inductive coupling from the mains or output transformers of the amp they are sitting on. All that said, in practice, they work, and work well". - David Buckley.

"Thanks for a couple of excellent pieces of kit: just got two D1-2s to add to my DI-3: a 15-year old veteran that is still going strong! " - Mike Willoughby - melodeon, bouzouki, guitar, harmonica with Ceilidh band Striding Edge,

"I have been using MTR DI boxes for over 10 years now with flawless performance and these dual passive ones are no exception. I have always found them to be well built. You get the feeling you could drop them from a lighting rig and they'd still work. The sound quality is also very good. The features are very user friendly with a ground lift, a -10dB and -20dB level reduction switch for hot signals and a link output for connecting a separate amp or monitor. The value of these are very good as well. I have used cheaper brands but the quality just isn't as good.

Reviewed By: Matt Rowbottom, c/o Absolute Music, Poole

DI-1 & DI-2P______________________________________ _Passive Direct Injection Boxes

 Photo MTR DI-1 passive DI box A single channel very high quality passive D.I. box, housed in the same all steel box used for our active models. It features a 47Kohm jack input socket, three position attenuation, and link output for connection to an on-stage combo etc.

Uniquely, it is fitted with two wide band low distortion transformers, one on each leg, providing a totally isolated, balanced 600 ohm output to an XLR.MTR DI-2P 2 channel passive DI box   A ground lift switch is fitted, and the unit can also be used in reverse to unbalance a balanced signal - useful when feeding a phantom powered balanced mic into a mono input such as an unbalanced mixer-amplifier.  Another application: if you like the sound that your guitar/bass/vocal learning device gives (e.g. Tascam CD-GTMkII) you can connect it to the DI box input, and the output to your guitar/bass/PA amp, to retain the sound of the trainer. Weight: 0.4Kg

The DI-2P is a two channel version in a slightly larger sized box, for stereo keyboards etc., or two discrete signals.  Weight: 0.5Kg



PS-4, PS-4v and PS-8, PS-8v_____________________________4 and 8 way Passive Splitters

Photo MTR PS-4 passive stereo 4way splitterA tough plastic box houses one stereo jack input feeding 4 stereo jack outputs. The sockets are pcb-mounted, and there is an internal link to mono the unit. Used for example, for splitting headphone signals in music rooms, computer music recording systems and hi-fi systems, it will also work in reverse as a 4 into 1 passive combiner. Dimensions are 120x75x39 mm., weight 12 grammes.

Another version, the PS-4v, right, has two additional volume controls, operating on channels 1 and 4.


Photo MTR PS-8 stereo 8 way splitter

The PS-8 is an 8 output version in an all-steel, RF shielded box. Dimensions: 208x73x44.  Weight 60g.


The PS-8v has volume controls on channels 1,4,5 and 8, better for use with headphones of differing impedances. All outputs on all models are fully protected by a 10 ohm resistor.  Weight 65g.


AL-22S_________________________________________________________Cable Splitter

If it is only necessary to have a two-way split with very light duty use, the AL-22S is a short splitter lead to enable two pairs of headphones to connect to a single output.  It is generally agreed that rigid 'Y' adaptors put considerable strain on the output socket and that a short, flexible lead is less likely to cause problems over time.


Technical Information:

6.3mm stereo jack plug to 2x 6.3mm stereo jack sockets. Length:200mm


AE-2___________________________________________________________Audio Signal Extender

AE-2 Audio Extender

Another simple, cost-effective idea; on computers without a break-out box, instead of constantly diving round the back to connect mics, guitars, headphones etc, use the AE-2 to bring one mono and one stereo socket out to a convenient box.

The sockets on the box are a standard mono and a stereo 6.5 dia jack, connected to 75cm of cable, terminating in a mono standard jack (for guitar/mic inputs) and a stereo minijack (for stereo line or stereo headphone inputs or outputs). Other plugs, such as a mono minijack, can be fitted to order. Minimum 25 pieces.



Proline & Studioline_______________________          _Acoustic Foam Sound Absorption Panels

MTR's acoustic foam panels are simple to use, attractive in appearance, and a highly effective method of reducing unwanted sound - the direct resonance and reflections in the room are dampened, and sound penetrating to and from outside the room is substantially reduced. Proline panels are 1 metre square, Studioline are 1.2m, both can be tacked or glued using a proprietary adhesive to walls, doors and ceilings.

Photo MTR Proline soundproofing panel

Proline                  143/153/173

The Proline range offers optimal qualities of damping at very sensible prices. The profile is domed-shaped, and panels are available in thicknesses of 40mm, 50mm and 70mm. Material density is 30Kg per cubic metre, and the colour is a mid to dark grey. Since the method of cutting means that the edges of adjacent panels may not have an identical profile, a wooden bead strip can be used across the joins.

Photo MTR Studioline soundproofing panel


Studioline              253/273/293

This pyramid shaped range has a striking appearance, and is used for its visual appeal as well as sound absorption. It is very efficient at sound damping because of a greater surface area is exposed to the sound. Thicknesses available are 50mm, 70mm and 100mm, again in mid to dark grey. Adjacent panels align exactly.
Recording and broadcast studios, clubs, discos, distance learning classrooms, architectural acoustics, houses of worship, theatres, auditoriums, gymnasiums, home theatre, residential, teleconferencing and videoconferencing environments, as well as all types of industrial noise control, and even office environments and noisy, hard-surfaced restaurants will all benefit from using Proline and Studioline.

All MTR panels are fire-retardant to the following specifications:
BS4735 or ASTMD 1692, FMVSS 302, ISO 3795.

 Typical Profiles

            Absorption Graphs

Profile of Proline 153 soundproofing panel

Profile of MTR Studioline 293 soundproofing panel

MTR acoustic foam Absorption Graphs

Minimum order quantity for delivery in 10 working days:  Proline 143: 26 panels, 153: 22 panels, 173: 16 panels.  Studioline 253: 20 panels, 273: 14 panels, and 293: 12 panels.  As these panels are made in pairs, please always order an even number.

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