VC7 – Manual

[crimsonsounds]

Hi Ted !

I just bought a VC7 and I’m looking for a manual if there’s one around.

I’m wondering how the M&S works on it – and also, how to switch between impedences without sending phantom to the wrong mic by accidents !

I only found out these existed last week when I came across one on Ebay and I bought it this evening

Thanks for any help,

Kind regards,

Al.

[Ted Fletcher]

Hi Al, I don’t have very much info on the VC7…. it was a unit that I designed when I started experimenting with MS recording.
The MS system on it is simple…. the ‘M’ output is simply the sum of the 2 mic amps, the ‘S’ is mic amp one mixed with a reverse polarity output of mic amp 2. So, if you drive a cardioid mic into mic 1 and a figure-8 mic into mic 2 (with the fig-8 mic at rt angles to the cardioid one,) the MS outputs become right and left. (Read it up on the airSOUND websight.)
You should not have any problems using the mic amps… they are transformer balanced, and very high quality.

[crimsonsounds]

Hi Ted,

That’s great – I’ve been reading up on the M&S and I get it now. I haven’t seen the back of the unti properly yet so I’ll probably understand once I see it.

What about the Phantom Power when switching between the impedence variables ? When using a non phantom mic, Is it possible to send Phantom out the output when switching past a value that applies the phantom – or should I switch the unit off if I have to sweep past a phantom enabled setting before I get to a non phantom one ?

Phantom makes me nervous – that’s all

Thanks again,

Al.

[Ted Fletcher]

Phantom shouldn’t make you nervous! It’s perfectly safe as long as you know the rules….. With the VC7 (and with any other mic amp) it’s a good rule to turn down the output gain before plugging or unplugging a microphone, for the comfort of your monitor speakers! And it’s sensible on the VC7 to select the mic impedance setting before plugging in, although I must admit, I am very cavalier about such things, and I happily switch through the impedance range without unplugging. All professional microphones are perfectly happy with phantom power being applied to them; the only warning is DONT use phantom power via a conventional jackfield…… plugging in a jack with phantom power applied can put 50volts across the mic which could cause damage…. particularly with ribbons! The BBC used to do this and it caused mayhem for several years. With XLR connections the problem is eliminated.
The most serious problem that can happen with phantom power is to accidentally plug an equipment output into a phantom powered mic input…… this can and does wreck some expensive output stages…. I had one here for repair 2 weeks ago. 😯

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