The 8-slot API 500 lunchbox and the D-sub 25 connector

Cheaper than their 6-slot option, the API 8-slot 500 series lunchbox is a very good buy, making it even easier for home studio owners to join the 500 series bandwagon. But why is it cheaper? There are two reasons ..

1. Firstly it uses an external PSU power brick. Inconvenient if portability is your primary concern but no problem when installed in a studio. 

2. The second reason is that instead of using XLR connectors, all sixteen audio connections are on two d-sub 25 connectors (8 balanced connections per d-sub connector).

The API 6-slot lunchbox (bottom) with built-in PSU and XLR connectors
and the more affordable 8-slot version (top) with external PSU brick and D-sub 25 connectors

If you've shied away from this type of connector in the past, now might be the time to dip your toes in the water. Their compact size, affordability (yes, quality XLRs are expensive) and increasing popularity with hardware manufacturers are three compelling reasons to learn both how they work, and how to wire them and make your own looms. Providing your soldering is up to scratch, audio quality will be identical to using XLRs. Perhaps even superior if the d-sub connectors you buy have screw locking connectors.

Sure, you can purchase d-sub 25 to XLR looms but they are expensive, and if you plan to wire your API lunchbox to a patchbay you will want bare wires instead of XLRs at one end of the loom, and a cable length that is right for your needs. The solution is to buy two d-sub connectors, a length of 16-way balanced multicore, and get soldering.

RS sell an excellent quality connector which you can find here .. http://uk.rs-online.com/web/p/d-sub-connector-kits/7659508/

Studiospares sell an excellent 16-way balanced multicore cable .. https://www.studiospares.com/Cables-Leads/Cable-Multicore/Sommer-Mistral-MCF16-16-Way-Multicore-Cable_546340.htm

Yamaha and Tascam adopted the d-sub 25 pin connector in the 1980's for multi-channel interconnection between digital recorders and mixers but chose to specify different wiring schemes (so called pin-outs). Fortunately for us, today most manufactures use the Tascam pin-out arrangement.

In the Tascam pin-out only 1 of the 25 pins is left unconnected (pin 13), so each audio channel has ground, live and return (3 X 8 =24). This means full professional balanced connections for 8 channels of analogue or AES3 digital.

Tascam D-sub 25 8 channel pin-out (G=ground, C=cold, H=hot)

Soldering a d-sub is fiddly, but once you figure out the correct lengths to strip and tin your cable cores, you'll quickly get the hang of it. It goes without saying that you should use multicore cable with numbers clearly printed on the insulation.

So the message is, don't be put-off by D-sub connections on gear, if you can solder, you can solder a D-sub!

Thanks for watching and reading.

FairFax