Klark Teknik : 3-pin hot interface

[TBird]

I recently discovered that Klark Teknik was originally a British firm; not a German one, as I had previously assumed. So why did they use the '3-pin hot' convention on all of their XLR sockets and not '2-pin hot' like the rest of the UK?

How do I safely interface a Klark Teknik DN360 dual channel graphic EQ (3-pin hot) to the rest of my system (2-pin hot)?

[Drew Stephenson]

Make up a short pair of converter cables, clearly label them, and leave them plugging into the back of the KT unit?

[James Perrett]

If everything is fully balanced then it doesn't matter.

[Hugh Robjohns]

I recently discovered that Klark Teknik was originally a British firm; not a German one, as I had previously assumed.

Amusing assumption!

Founded by Phillip and Terry Clark in 1971, initially selling equipment under the Klark brand name. Later, their products adopted the Teknik name, and then Klark Teknik by the mid 70s. But they were always based in the UK midlands, in Kidderminster near Birmingham.

So why did they use the '3-pin hot' convention on all of their XLR sockets and not '2-pin hot' like the rest of the UK?

There was no globally defined standard for XLR wiring until the early 90s, believe it or not!

In America, Ampex decided back in the 1950s to use pin-3 hot in XLRs for a couple of reasons. First, it was convention back then to order balanced signal connections on barrier strip terminals as screen, cold, hot, and hence pins 1,2,3.

Secondly, pin 3 in the XLR is the most easily identified (being the middle one!) so making it the hot terminal kind of made sense...

Consequently, most US equipment settled on pin-3 hot, and I guess since US outboard gear dominated recording studios at that time, KT simply followed suit.

However, in Europe, the IEC officially defined pin 2 hot in 1975 in its Standard IEC268 document, specifically in the context of microphones. But this formal standard was rapidly adopted for other balanced equipment in Europe and the UK, and then all around the world too (in America first by the SMPTE).

The Audio Engineering Society confirmed the pin-2 hot convention in its AES14 standard in 1992!

How do I safely interface a Klark Teknik DN360 dual channel graphic EQ (3-pin hot) to the rest of my system (2-pin hot)?

Assuming balanced connections in and out, there are no special interface requirements in a notionally pin-2 hot system. The signal will be inverted going into the KT box, and inverted again on the way out, so overall it makes no difference. It's just that the signal is 'upside down' inside the box... which makes zero difference to anyone!

The pin 2/3 hot issue is really only relevant when connecting in an unbalanced system.

If it really bothers you, rewire the KT unit's XLR connections to conform with the pin-2 hot standard... but in a fully balanced connection system there's really no point.

I dont recommend making up polarity inverting cables because they'll make no difference to the operation of the KT, but may cause confusion if used accidentally with microphones or loudspeakers!

[ef37a]

https://www.technicalaudio.com/pdf/Klar ... manual.pdf

Floating, transformer balanced James!

(Oh! Those were the days!)

Dave.

[James Perrett]

https://www.technicalaudio.com/pdf/Klar ... manual.pdf

Floating, transformer balanced James!

(Oh! Those were the days!)

Dave.

Looking at page 5 of the manual, it seems they were supplied with unbalanced outputs as standard with transformer balanced outputs as an option but in the next paragraph they made the same point as I did - it doesn't matter which is which in a fully balanced system.

[TBird]

Thank you for all of your replies. That was very illuminating. Mystery solved.

[tacitus]

Indeed. That information won’t ever make me richer, warmer, safer, less hungry or more desirable, but it still makes me happy!