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Post by jcoutu1 on Sept 22, 2014 13:21:37 GMT -6
I sold my Chander Germanium Tone Control EQ, and the guy that got it is having a problem. "Was playing with a direct bass and at one point turned the Presence on (any freq + any level of gain in that band) and got staggering ultrasonic feedback. (Attached -- please mute your speakers!)" Any ideas what would be causing something like this? tonycamphd or svart maybe? Any other techie guys? Make sure your volume is WAY down before playing. www.dropbox.com/s/mz8yyjjwzwn138a/Germ%20Tone%20Control%20Noise.wav?dl=0 |
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Post by svart on Sept 22, 2014 13:35:01 GMT -6
Sounds like oscillation of some type, not necessarily feedback.
I'd find out if it still happens if the buyer gets it to do this, then unplugs whatever they have plugged into it. If it goes away then it's either the source, or the combination of the source and EQ.
I'd also find out if it's an active bass. I've had random issues with active basses and DI inputs since the active bass has a much lower output impedance and is usually more well suited to be plugged into line impedances.
Other possibilities are ground loops and a power supply going bad. Downconverted switching from a power supply can sound like that if there is something wrong with it. Sometimes ground loops can spur oscillation or transfer switching noise from other sources.
The buyer might just have to do some investigation and narrowing down of possible sources, especially since it didn't happen until they got it..
EDIT: I just looked up the EQ.. it's just an EQ, no DI at all.. So I'd say we need more info about how the buyer has things set up. I'd still have them get the problem to happen and then unplugging the input.. Might still help narrow this down.
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Post by jcoutu1 on Sept 22, 2014 13:46:56 GMT -6
Sounds like oscillation of some type, not necessarily feedback. I'd find out if it still happens if the buyer gets it to do this, then unplugs whatever they have plugged into it. If it goes away then it's either the source, or the combination of the source and EQ. I'd also find out if it's an active bass. I've had random issues with active basses and DI inputs since the active bass has a much lower output impedance and is usually more well suited to be plugged into line impedances. Other possibilities are ground loops and a power supply going bad. Downconverted switching from a power supply can sound like that if there is something wrong with it. Sometimes ground loops can spur oscillation or transfer switching noise from other sources. The buyer might just have to do some investigation and narrowing down of possible sources, especially since it didn't happen until they got it.. EDIT: I just looked up the EQ.. it's just an EQ, no DI at all.. So I'd say we need more info about how the buyer has things set up. I'd still have them get the problem to happen and then unplugging the input.. Might still help narrow this down. Thanks man. Yeah, I assume he doesn't have his bass plugged directly into it, but I guess I don't know. I asked a few more questions. |
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Post by svart on Sept 24, 2014 7:51:13 GMT -6
You ever hear back from the buyer about this?
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Post by jcoutu1 on Sept 24, 2014 8:09:16 GMT -6
He was using a passive bass > Radial JDI > GML Preamp > Tone Control EQ. He's only getting the oscillation on the the presence band with any amount of boost or cut. No noise when it's flat. He said he's getting the sound independent of the source.
I emailed Chandler with the info and sound clip and they basically said they don't know and I gotta send it in. "It could be a number of different things including the amp, a capacitor or the power supply." I think the buyer and I have it worked out where he's going to pay to ship it to Chandler and I'm going to cover the repair and return shipping. Chandler's bench fee is $50/hour + parts and shipping.
It sucks because the EQ was working tip top before I shipped it out. I packed it well and paid $70 to ship it across the country insured via UPS and it arrived to him with an issue. He said the packing was great and the box wasn't damaged at all. Do you think I can make a case to UPS to have them cover the cost? I feel like I'm SOL if the package doesn't look physically damaged right?
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Post by svart on Sept 24, 2014 9:20:49 GMT -6
Well, I'm curious what Chandler finds out. It's unlikely that UPS would pay unless there was physical damage to the box itself. It's also unlikely that a drop or shock could damage a unit but not the box, unless it fell on a flat side from a great distance. From the pictures of the inside of the chandler products, they have some pretty good looking assembly, so I dunno if it's likely that anything would break loose.
It's possible that it had a problem develop or had one from the start, but your setup never showed the issue.
I had some Earthworks mics that were like that. Early models would only work correctly with certain preamps. I never noticed any issues until I got preamps with transformer inputs, then those Earthwork mics would oscillate like hell on those preamps, but not others. Strange.
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