Legacy microphone connectors

I could do with some help. We have 100' of microphone cable from around the 1960's (together with an old ribbon mic and transformer).

The ribbon mic + transformer are not sufficient for our needs and I bought a modern mic which has XLR type connection. I thought the cable we had would fit but the cable connectors are a little larger and have a collar which the modern mic doesn't have.

Did the standards change? Were the old connections proprietory or standard? How do I get from one to the other?

Thanks for any advice.

Reply to
AnthonyL
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At one time most mics used their own specific connectors. These can be obsolete.

If say your mic cable has non XLR at both ends simply cut it and fit XLRs. You can then either plug those together and it will work as before, or insert an XLR extension. Ebay is quite a good source of 3 pin XLRs.

Note mic cables don't follow normal practice in that the mic input on the amp is female. This is because of powered mics which normally run on 48v DC - so prevents you touching live pins. In other words the XLR on the mic has pins, a male.

XLR connections are thus

1 3

2

And marked as such.

1 is screen 2 is cold 3 is hot (often red)
Reply to
Dave Plowman (News)

I'm an idiot - should be

1 2 3

The whole point in posting it is it doesn't look logical. ;-)

Reply to
Dave Plowman (News)

Dave, with swapping the pin config I think the hot/cold got swapped too. XLRs are normally:

1 screen 2 hot 3 cold Although (just to be contrary) some older US gear has the opposite phase

Charles F

Reply to
Charles F

Yes. Sorry about not correcting that too.

The idea of that pin configuration is being able to link 1 (screen) and 3 (cold) easily for unbalanced connection. I think.

Reply to
Dave Plowman (News)

In article , Dave Plowman (News) scribeth thus

But if the other end is wired the same then no difference;)...

Reply to
tony sayer

Indeed - but not good practice, when you may not be able to see or check the other end of a cable, esp. in fixed installantions.

Charles

Reply to
Charles F

In article , AnthonyL writes

Back on topic, what you have sounds like a Reslo connector, used by them and Grampian (IIRC) and a few others in the 1960s and 1970s.

They're identifiable thus:

- the pins are fatter than those of XLRs, but still in a fairly even triangle

- there's a clamping ring with a screwthread, and

- a fat indexing lug on the side of the connector (around 1/16"), and a slot cut in the side of the mic receptacle (not a groove per XLRs).

It's just possible that it's a Coles connector - that has the three pins in a flatter triangle, almost a straight line. There's no clamping ring, but a slot at right-angles to the connector (there's a pin in the mic that catches in this to lock the connector in place.

The Reslo/Grampian style were common in the BBC and elsewhere for lower-grade mic uses such as talkback. You often found them on the end of goosenecks. Mics using that connector were in production well into the 1980s, pretty much all were unpowered, moving coil.

The Coles ones are still current, for a very small range of mics (4038s), as they're retro-styling and buyers like that consistency.

As others have suggested, you can simply cut the cable and insert XLRs to extend it or shorten it as much as you wish.

Ribbon mics were often made to 30 Ohms. This was for two reasons: it was an early mic impedance standard, because it worked well on long twisted-pair cable runs (lower losses), and, because ribbons have an extremely low resistance, the impedance-converting transformer at the mic end could be cheaper (the bigger the impedance change in one jump, the harder it is to make a suitable audio-grade transformer).

Prior to XLR ubiquity, BBC studio wallboxes used to use Cannon EP-8 connectors for mic cables. The eight pins included connections to an impedance matching transformer built into the wallbox, specifically for low-Z mics, so the mixer only saw around 300 Ohms. So the mic cable wiring went to different pins on the EP-8 depending on its impedance!

If your (Reslo?) mic still works, there's a good market for it on eBay, but you'll need to sell it with the transformer, otherwise the buyer will probably wonder why the output is low and covered in hum!

S.

Reply to
SpamTrapSeeSig

I remember by saying to myself 'Screen-Line-Return', Pins 1-2-3, 'SLR', which is pissed talk for 'XLR' :-)

And the Japanese use the opposing sex, males for inputs, females for outputs. A few OB companies use the same sex for everything on their tailboards and external cable reels, that way they can never have the cables the wrong way round !

Reply to
Mark Carver

Wouldn't that correctly be called an STC connecter? Coles being the later owner of the brand?

FWIW, that connector is called a thistle at the BBC as it first appeared on the STC moving coil apple and biscuit or thistle mic. 4021? Also used on the classic 4038 ribbon and 4033 'guiness bottle'.

Reply to
Dave Plowman (News)

In the early days of XLR, they were used in the conventional way. Ie, the output being a female. It was only when phantom power arrived that it was changed round for mics, for H&S reasons. Using XLR for things like 100v line speakers followed the original convention - as did some line level things like tape recorders. Basically rather confusing. ;-)

Reply to
Dave Plowman (News)

Also, a female 'Telefunken figure of 8' power connector is a perfect fit for the two 'horizontal' pins in a 3-pin XLR male.

A colleague had to attend to the charred remains of a cheap mixing desk that had the lethal (literally) combination a figure of 8 power connector, and someone plugging it up blind, by reaching over the back.

Reply to
Mark Carver

In article , "Dave Plowman (News)" writes

Probably, but available from Coles now. I'm not sure if the latest 4038 incarnation is that or XLR - I suspect it's still the old one.

Yes. There's one on the 4021 I own. Time was when they were 'bowled' up over the girders of the stand roofs at football grounds for crowd FX* - handy to have a strong plug-socket combination in that context.

S.

  • usually the version with the integral windshield - can't remember the type #.
Reply to
SpamTrapSeeSig

Luckily that figure of 8 mains connector was never used on pro gear. Which would have an earth too.

Reply to
Dave Plowman (News)

I do remember the changeover in the BBC Film Units which was in the

1970s. I think the Nagra IVS recorders started it, coming with female sockets on the recorder to provide phantom powering for Sennheiser mics. But it took a time for all of the industry to change and you could often get the "wrong" sex on hired equipment which meant carrying around several back-to-back XLR sex adaptors just to be safe.

Jim.

Reply to
Jim Guthrie

Well there is no excuse anyway:

"Always run away with the female"

or for female sound assistants:

"The male end goes in".

Reply to
Dave Liquorice

Far worse was Anglia TV - they used the wrong sex for LNE mains. So OB types had to carry adaptors for use on shared sites.

Reply to
Dave Plowman (News)

So in the late 60s did BBC RD.

Reply to
charles

In article , Charles F scribeth thus

No course not but I have seen them wired with just white cables so a continuo check was needed to determine polarity...

Reply to
tony sayer

I think you meant "Gender Benders". In fact, you seem to have misused 'sex' for 'gender' elsewhere in your post. :-)

Reply to
Johny B Good

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