Troubleshooting Apex 460 Mod

mpedrummer · Post by **mpedrummer** » Thu Dec 03, 2009 6:33 am

Hello, all!

Earlier in 2009, I did an Apex 460 mod, very, very pleased with the results. However, it's developed an issue recently, and I've reached my limit of "knowing where to start"

Granted, it didn't take long to get there

Here's the deal: it's omni. All the time. I was expecting that this meant one of my solder joints had come undone and disconnected one side of the capsule - that would make it omni only. Unfortunately, my solder joints are all holding true.

I still need to verify that the 7-pin cable is passing signal on all 7 pins, but after that, I'm not sure where to begin.

Tips? Tricks? Books I should buy/read/attempt to understand on my own before asking people on the internet to think for me?

Thanks
Tim

Nate Dort · Post by **Nate Dort** » Thu Dec 03, 2009 6:45 am

if it's something that's cropped up recently, the most likely culprit is the cable. it gets the most wear and tear. one of those 7 pins is used to send varying amounts of voltage to the rear of the capsule. i'm guessing that pin has an open somewhere along the length of the cable, probably right near one (or both) of the connectors. or a cold solder joint that has finally worked it's way loose.

mpedrummer · Post by **mpedrummer** » Thu Dec 03, 2009 6:49 am

That's my hope - the cable seems a little shoddy (it's the one that came with the Apex 460) especially at the ends. Just feels like the connector isn't doing much in terms of "strain relief"

antilog · Post by **antilog** » Sun Dec 06, 2009 9:45 pm

What mod?

mpedrummer · Post by **mpedrummer** » Mon Dec 07, 2009 6:07 am

There are much better components available for that particular Chinese mic. I replace the capsule with a Peluso CEK-12, replaced the transformer with a BV11 from Dave Thomas of AAMicrophones, replaced the tube with a NOS 12AY7, removed some filtering capacitors (C5 and C6, maybe?) and replaced another cap (C8?)

There doesn't seem to be a single writeup of what I did...I sourced my ideas from a large number of forums, etc, and ironed out some troubles I had here on TOMB.

The difference was HUGE. The capsule made a hige difference, the transformer made a big difference, the capacitor changes made a subtle-but-worth-it difference, and the tube made a surprisingly (to me) difference. Someone who knows what they're talking about may not find the tube part to be surprising, I dunno

Tim

mpedrummer · Post by **mpedrummer** » Wed Dec 09, 2009 1:15 pm

Huh...weird.

Pin 2 is not exactly broken...but sure doesn't work. Checking resistance from pin 2 input to pin 2 output, it jumps all over the place - probably just because it's intermittently losing the connection completely, and my multimeter is showing me a rolling average? It goes from ~3ohms, which is what the other pins show, to 200ohms, and sometimes just breaks completely.

So, resoldered the end that looked dodgy.

The weird bit here...it's reliably 3ohm from the solder side, but still jumpy on the pin side. Er...?

So, I'm thinking the connector itself is dodgy, and I should either buy a new 7-pin XLR and redo the whole thing, or just buy a new cable?

Tim

mrc · Post by **mrc** » Wed Dec 09, 2009 3:24 pm

There ya go! You might just look at Redco and get what you need.
mrc

rodabod · Post by **rodabod** » Thu Dec 31, 2009 4:47 am

You could also check the correct polarising voltages are being sent from the PSU. I can't remember the schematic off the top of my head though.

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Troubleshooting Apex 460 Mod

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