EZ1290: The Ongoing Saga pt.2

I was in the studio the other day recording guitars for a demo of some new Cabinets of Curiosity music. I had my Vox set up in the tracking room and I was pretty much ready to go. When I turned up the gain on my 1290 though, it seemed like my guitar tone was a lot more overdriven than it should have been.

I started to panic immediately. A few days prior I had been recording some acoustic guitar for the same project. I was using the built in preamps in my UA Apollo 8 so I could control the preamps functions from the tracking room. Unfortunately, I didn’t realize that I didn’t have the patch cable necessary to bypass the 1290 out of the signal chain. So I turned on phantom power without even really thinking about it, suffered a mild heart attack, and smashed the button to turn it off again. I then sat for what seemed like an eternity waiting for the phantom power to dissipate.

2017-09-28 10.05.11
It’s all your fault!

I thought I was in the clear until the other day when I started hearing the distortion. Later that same day, I had my good friend and Cabinets colleague Bran Blackmire over to record his guitar tracks. I patched him through my Warm Audio Tone Beast to avoid any headaches. But once he was done, I took the 1290 out of the rack and popped it open to try and diagnose the problem.

Unfortunately, I couldn’t. Everything looked pristine on the inside, but when we tested it again, we kept getting the same static noise from before. I ended up going to the GroupDIY forums for advice, and I’me very glad I did.

It was quickly pointed out to me that the phantom power couldn’t have caused any of the problems I was experiencing because of the way the preamp was designed. Because the 1290 utilizes big iron input and output transformers, anything between them is shielded from phantom power and other unwanted electrical nuisances.

Carnhill
Thanks, pal

But that raised another problem: If my problem wasn’t caused by phantom power, what was it caused by?

After about a half-hour of digging through forum threads, I finally found some user experiences that sounded similar to mine. Lots of popping and static, specifically when turning the rotary switch. So firstly, I reinforced all of the solder pads that the switch was connected to for good measure. Secondly (and this, I think was really the cause of my problems), I tightened a couple screws.

2017-09-28 09.59.56
It’s all YOUR fault!

That big transistor pictured above is responsible for a lot of the signal that comes out of the gain stages of the preamp. It’s held onto the PCB by two solder pads and a couple of nuts and bolts, those nuts and bolts in turn act as a sort of grounding bridge. As it turns out, the vibrations from my studio monitors had loosened the nuts and severed the grounding connection that they made, causing all sorts of nasty static. A few turns of the screwdriver and a couple dabs of loctite later and they’re back up and running, good as new!

A have to send a big thanks to the GroupDIY forums, as I would have never thought to check that, or that it would ever be an issue in the first place. But, I’m glad that my favorite preamp is back in working order. Now I just have to finish the next three channels!

 

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