[Ted Fletcher]

Yes, that’s the ‘Joe Walsh’ Alice…… I remember it well because I delivered it personally to Boulder Colorado and was able to ‘hang out’ with Joe and the band.
The channels operate on 15-0-15, I advise against pushing them to 18V, they may stand it but it affects reliability.
The meters are probably 24V, but we always run them on 15V AC nowadays, it makes them last longer.
I’m afraid I don’t have any drawings for that series (It was a ‘Trackplan’ mixer) but the circuitry is very simple…. nothing over-clever…. It was a good design and sounded great, mainly because of the simplicity and plenty of headroom.

[Ted Fletcher]

So now people are finding them on the side of the road!!
I’m sending you the circuit diagrams that I have by email direct.
When you clean the pots, DONT use switch cleaner! Those Omeg pots tend to wear badly when they are cleaned by a fierce cleaner…. use WD40, and if you have any of the new synthetic spray-grease, use a tiny squirt of that as well. Using switch cleaner can wreck the pot track!
😯

[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. 😯

[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.

[Ted Fletcher]

Hi Alex,……. Well, I’m the same age as you except that the numerals are in a different order!

Yes, I think that one is a ‘brick’….. they are very good, and yes, they do have the effect of pulling the voice forward and yet keeping it clean and fresh sounding.
There were only about 50 ‘bricks’ made, and they did vary quite a lot, as I was experimenting with the design, but basically they were just very accurate mic amps with transformer inputs and with amplifiers that had a huge overload margin. The compressor was very simple, but the best thing was the ‘enhancer’ which worked like a dream.
The P110 is the successor to the ‘brick’ and it does sound just as good.
It’s unlikely that you will find a ‘brick’ at a price less than about £600; they are very rare as engineers tend to hang on to them!
But don’t get fixated about it! The most important thing is the voice you are recording, not the gear.

[Ted Fletcher]

Yes, I’m happy to have a look at that one!
Just send it to me at the Sound House and email me direct with the return address. As you have seen before on the forum, I charge £25 as a fixed charge to service/fix anything (except mixers!) plus the cost of returning the unit to you.
It will be a pleasure to fix a VC7.

[Ted Fletcher]

That’s quite a rarity… I designed the VC7 to be the very best quality mic amp that it was possible to build. It’s very conventional, with a high quality transformer input, and with switching to match different microphones; it was well ahead of its time. I remember the design very well…. it was a problem to keep the mic transformer in channel 2 far enough away from the mains transformer; I did it by putting both mic transformers together at the left hand end.
I knew it would never be a big seller, but it was for my own benefit rather than purely commercial.
I don’t think we built more than 10 of those…. but it’s a brilliant mic amp.

[Ted Fletcher]

No, the VC3 never had a transformer…. it was always a solid state input, using the regular SSM mic input chip. The very early ones had a harmonic enhancer and the later ones had the EQ instead. I’m afraid I don’t have a record of when we changed the models.

[Ted Fletcher]

In common with all those smaller designs, I standardised on 12VAC as the power requirement…. this makes it easy for replacement.
We have these power supplies in stock at £14 plus postage (inc VAT). Please email me direct at [email protected] to tell me where you are located….. we have UK, Euro and US versions. I can then let you know the postage and you can pay by paypal.

[Ted Fletcher]

There’s a nice simple answer to this one…. If it’s my design, then any balanced output can be treated as unbalanced if you like.
It’s a good rule to try to keep everything balanced , but if you have unbalanced ins or outs on other gear, then it will all work fine.
The only thing to watch, when going from balanced to unbalanced, always make sure that the -ve leg is connected to ground…. never leave an input or output pin floating around connected to nothing.

Regarding the transformer in the VC1 V2.01 I think I recall that it is the same as the brick…. the circuitry is certainly similar. It was shortly after the V2.01 that we changed to a transformerless input, and it was not as good.

BTW, I always said that the C2 was the neatest one of them all…. It was as good as the SC2 but very few people bought it…. it was too compact and neat! 🙄

[Ted Fletcher]

OK, got the pictures! This is a really nice mixer!
It was made basically from 828 channel modules with a special group section incorporating talkback. It was built originally as an outside broadcast mixer for small live events…. I wish I could remember the radio station it was built for…… possibly Edinburgh, or Tyne/Tees, or may even have been Cardiff.
The giveaway is the back panel where there are sockets for external battery input! There is one oddity…. it’s fitted with VU meters; most of our radio station mixers had PPMs. It would be interesting to know its history.
‘B-check’ is an input for checking the output of tape machines.
It looks in pristine condition and I’m sure it will work well. The circuitry uses ICs and it’s likely that the outputs will be balanced, although I can’t be sure…. I don’t have the circuitry information for this one…..
The inputs will certainly be Sowter transformers. The direct channel outputs will be unbalanced, as will the aux inputs.
The faders look like 100mm Penny and Giles….. this was a very expensive mixer in its day.

[Ted Fletcher]

Sorry, your pic did not resolve on my computer….. can you try emailing direct ([email protected])?

[Ted Fletcher]

I need to know a bit more about the mixer…. we built a number of mixers using 828 technology, and I have the circuitry for that, but there were a number of others that are lost in the mists of time.
If you can post (or email) a pcture of the mixer top, I can probably work out what it was….. most were unbalanced unless they were for use in radio stations.

[Ted Fletcher]

Yes, that sounds very much like a fault in the 4016…. this is used as the change-over switch in the PFL circuit, so that would be it. 😥
But you are getting there!

[Ted Fletcher]

Hi Thomas, the IC you talk about is the Harris 4741 and it is probably difficult to source now. It is simply a quad version of the 741 and has the same connections as the TL074, and you could probably replace it directly with the TL074.
I will email separately with the circuit diagrams.

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