Technical Questions Answered by Vic Lennard

Dear MT,

Early last year, I purchased a Moog Rogue analogue synthesiser which came without a MIDI to CV converter. Could you please inform me where I can purchase one?

D Bircham
Sheffield

A While you could buy a MIDI to CV converter 'off the shelf', you would be better to have your Rogue MIDI-retrofitted because of the extra facilities this would provide. The Kenton Electronics retrofit, for example, will provide you with MIDI In and Thru sockets - the former conveying MIDI note, pitch bend, modulation and sustain pedal information to the relevant circuitry in the Rogue.

Additionally, aftertouch from a MIDI keyboard can control either pitch bend or modulation and the filter cut-off frequency can be controlled via the velocity of a note, any MIDI controller or aftertouch. All settings are retained when the Rogue is turned off.

At £199.75 inclusive of fitting and VAT, the retrofit certainly isn't cheap, but if you like the sound of the Rogue and you want it to work properly over MIDI then it is certainly worth considering. More information from Kenton Electronics on 081-974 2475.

Dear MT,

I've a broken Oscar mono-synth which I bought off a guy in Harrow about five years ago. First it worked a treat but then it stopped and has spent the past four years in a repair shop in Leeds (they can't find a circuit diagram). Please could you tell me who could fix my Oscar?

Finn O 'Leary
Leeds

A Actually, Finn, what you've got is a broken Oscar duo-synth - but I suppose that's little comfort if it doesn't work. The Synthesiser Service Centre should be able to sort you out; call them on (Contact Details). Repair charge is £35 per hour plus VAT and there's a minimum charge of 1 hour.

Dear MT,

I shortly hope to be buying a 1040 ST with C-Lab Creator software. Whilst I realise that this isn't ST Monthly, what I'd like to know is whether Creator will only run on a mono monitor and what is the difference between Atari's SM124 and SM125 monitors?

John Topley
Lincoln

A While Creator claims to be able to run in medium resolution (colour - 640 x 200 pixels), it is fair to say that the screen layout suffers badly under these conditions and that you should really be running in high resolution (mono - 640 x 400 pixels). The reason for this is that with only half the number of vertical screen pixels it is impossible to accurately display the vertical aspect of the screen and so some words tend to 'overwrite' those above or below.

The SM124 and 125 are essentially the same in that they are both high resolution, mono monitors. The SM125 has a swivel base and controls on the rear to adjust the vertical height while the SM124 has these controls buried inside. Consequently you can increase the vertical clarity of a program on the SM125 although circles may then appear oval-shaped - which is fine for music, but not exactly useful for desktop publishing!

If you want an SM125, you are going to have to find a secondhand one because they are no longer produced. You may find the SM124 is still available but you'd probably be better off opting for Atari's new mono monitor - the SM144. Though a little more expensive, the screen is flatter - and so better to look at - and the size of the screen image can be increased in both directions.

Dear MT,

While there have been many articles in magazines about getting rid of mains hum by breaking earth loops, none of them ever mention altering the MIDI cables in any way. As a MIDI cable has a screen, which must be earthed, surely the MIDI cabling can cause earth loops as well?

Peter Robard
Swansea

A This problem was carefully considered when MIDI was first designed and a solution found to prevent the situation from ever occurring. Data received at a MIDI In is transferred to a MIDI device via an opto-isolator, literally using light pulses and so prevents any direct contact between two MIDI devices. Pin 2 of a MIDI socket carries the ground for the shielded cable, but only pin 2 for a MIDI Out or Thru socket is actually connected to ground - pin 2 of a MIDI In socket is not connected to anything.

The point here is that every MIDI cable must be connected between either a MIDI Out and a MIDI In or a MIDI Thru and a MIDI In. By ensuring that the pin 2 of a MIDI cable is only grounded at one end, it is impossible for a correctly wired MIDI lead to cause an earth loop.

Got a problem? Vic has an answer. Write to: Technically Speaking, (Contact Details).