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Post by copperx on Jun 23, 2024 14:22:27 GMT -6
Hi!
I recently went to Mexico to record a band and took a few items, among them a Demeter tube preamp, and a bunch of 1173 clones. When I tried to record with the Demeter, I heard a hum of about -60db, which was constant in both channels and was not dependent on the input or output gain, and also independent of the microphone, and the DI had the same static hum. All of my other preamps were hum-free even at max gain.
When I came back to the US, I tested the Demeter again and it's clean as a whistle, even at max gain.
Does anybody know what could be happening here? One thing that I know about a lot of old Mexican wiring is that even though there are 3-prong outlets, the ground is not connected to anything (there is no ground). Could that be a cause? Or could the preamp be faulty in some way that is only seen when there is no ground?
Thanks a lot!
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Post by Tbone81 on Jun 23, 2024 14:25:24 GMT -6
I have a good friend who is an engineer in Mexico, he’s told me more than once that the biggest issue they face is with wonky power grids. It’s a problem all over the country. His preamp choices are mainly determined by what works well the power at any given studio… the noise you got is kinda par for the course.
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Post by mjheck on Jun 23, 2024 18:25:10 GMT -6
We lived there for three years - the power was extremely inconsistent - drops, surges and just plain outages. We had all kinds of protectors and shit on everything and it still caused strange behavior.
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Post by doubledog on Jun 23, 2024 21:59:45 GMT -6
why do they hum? Because they don't know the words!
(just wanted to beat someone else to it...)
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Post by copperx on Jun 24, 2024 1:07:59 GMT -6
So it's for sure dirty power and not a grounding problem, right?
If so, is there anything that I can do to ameliorate this? An isolation transformer?
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trappist
Junior Member
Posts: 73
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Post by trappist on Jun 24, 2024 1:19:11 GMT -6
I’ve played in Mexico City a few times and have waited outside Sala Nezahualcoyotll for hours waiting because the power grid failed. We had a good time though. In Mexico, things start when they start and they end when it’s over. Maybe bringing a Honda inverter generator along to the gig  |
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Post by doubledog on Jun 24, 2024 7:58:15 GMT -6
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Post by EmRR on Jun 24, 2024 10:10:28 GMT -6
So it's for sure dirty power and not a grounding problem, right? If so, is there anything that I can do to ameliorate this? An isolation transformer? Well....it'd be a grounding problem where they were plugged in. Could be one equipment on one ground path and something connected on another. |
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Post by svart on Jun 24, 2024 11:51:01 GMT -6
Hi!
I recently went to Mexico to record a band and took a few items, among them a Demeter tube preamp, and a bunch of 1173 clones. When I tried to record with the Demeter, I heard a hum of about -60db, which was constant in both channels and was not dependent on the input or output gain, and also independent of the microphone, and the DI had the same static hum. All of my other preamps were hum-free even at max gain.
When I came back to the US, I tested the Demeter again and it's clean as a whistle, even at max gain.
Does anybody know what could be happening here? One thing that I know about a lot of old Mexican wiring is that even though there are 3-prong outlets, the ground is not connected to anything (there is no ground). Could that be a cause? Or could the preamp be faulty in some way that is only seen when there is no ground?
Thanks a lot!
100% because of ground. What you're hearing is some kind of ground loop, probably through the preamp chassis and the interface. |
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Post by chessparov on Jun 24, 2024 13:14:03 GMT -6
Their infrastructure must have.... Loco motives. Their Electrical Engineers need more training. |
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Post by copperx on Jun 24, 2024 15:28:46 GMT -6
Hi! I recently went to Mexico to record a band and took a few items, among them a Demeter tube preamp, and a bunch of 1173 clones. When I tried to record with the Demeter, I heard a hum of about -60db, which was constant in both channels and was not dependent on the input or output gain, and also independent of the microphone, and the DI had the same static hum. All of my other preamps were hum-free even at max gain. When I came back to the US, I tested the Demeter again and it's clean as a whistle, even at max gain. Does anybody know what could be happening here? One thing that I know about a lot of old Mexican wiring is that even though there are 3-prong outlets, the ground is not connected to anything (there is no ground). Could that be a cause? Or could the preamp be faulty in some way that is only seen when there is no ground? Thanks a lot!
100% because of ground. What you're hearing is some kind of ground loop, probably through the preamp chassis and the interface. Ahh! That's good to hear. If I use this grounding spike, could it help? Or am I going to die?
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