I have a Darkvoice 332 and after warming it up and listening to it for about 3-4 hours, a constant rattling sound like machine gun fire or stove fire starter sparks started coming through my headphones. I've tested them on a couple of phones, removed the tubes and plugged them back in but as the tubes light up, the sound came back. What's wrong? I'm a complete tube amp novice.
Tube Amp Help!
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Alright... this is weird. I took my iphone away from the amp and the noise went away.
Stevesebastianb
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^^^Nothing weird, your iPhone is a RF device which emits radio frequency waves and the transmitted RF energy has entered into your audio amplifier. The two do not mix. This will happen with most audio amps if you place a strong RF source next to it!
This occurs when an audio amp has bad RF sheilding or the RF is picked up via cables which have bad shielding.
This occurs when an audio amp has bad RF sheilding or the RF is picked up via cables which have bad shielding.
Stevesebastianb
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The same thing can happen to SS amps, it is not an issue with your tube amp. Hope this helps?
atbglenn
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My cell phone makes one of my sub woofers go crazy if it's within a few feet. It's pretty much normal for cell phones to have this reaction on audio equipment
Skylab
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Yep - this is the "GSM noise". Note that 3G does not do this. Maybe an upgrade of your cell phone should be next
Uncle Erik
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Quote:
No, this is RFI noise and every cellphone makes it.
A cell phone is not really a phone. It is a small radio transmitter that puts out up to 0.25W of power. No matter the model or type, every cell phone transmits a radio signal to cell towers to communicate.
When your cell phone radiates radio waves - and it does this every minute or two just to check in - the amp and/or cables pick up the radiated RFI and it goes into the audio path along with whatever music you're playing.
The best fix is to just keep your cell away from your gear. You can also put an iPhone into airplane mode to stop it from automatically communicating. Shielded cables can also help.
The problem shielding against RFI, however, is that it's sort of like tryi g to waterproof something. RFI is invisible and it reflects off objects and gets in through the tiniest of openings. This is why distance is the best remedy - just put your phone on the other side of the room from your gear.
| Originally Posted by Skylab /img/forum/go_quote.gif Yep - this is the "GSM noise". Note that 3G does not do this. Maybe an upgrade of your cell phone should be next
|
No, this is RFI noise and every cellphone makes it.
A cell phone is not really a phone. It is a small radio transmitter that puts out up to 0.25W of power. No matter the model or type, every cell phone transmits a radio signal to cell towers to communicate.
When your cell phone radiates radio waves - and it does this every minute or two just to check in - the amp and/or cables pick up the radiated RFI and it goes into the audio path along with whatever music you're playing.
The best fix is to just keep your cell away from your gear. You can also put an iPhone into airplane mode to stop it from automatically communicating. Shielded cables can also help.
The problem shielding against RFI, however, is that it's sort of like tryi g to waterproof something. RFI is invisible and it reflects off objects and gets in through the tiniest of openings. This is why distance is the best remedy - just put your phone on the other side of the room from your gear.
Skylab
Reviewerus Prolificus
Uncle Erik - GSM is far, far worse a problem in this regard than 3G. You can easily search on this and read all about it. My Blackberry bold introduces NO noise when it's in 3G, which operates at different frequencies from GSM and does not make the same noise. When it drops to EDGE, the secific "GSM noise" is there. There is a very specfic issue related to GSM, and it's not the same with 3G. You can easily Google this if you're curious about it. A 3G phone (when in 3G mode) will not do the same thing.
Uncle Erik
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If the phone is transmitting radio frequencies, they can be picked up. Certain frequencies might not be attuned to your equipment (even things such as cable length can aid in receiving radio signals), but any time a phone transmits, there's a possibility that the transmission will be picked up.
| Originally Posted by Skylab /img/forum/go_quote.gif Uncle Erik - GSM is far, far worse a problem in this regard than 3G. You can easily search on this and read all about it. My Blackberry bold introduces NO noise when it's in 3G, which operates at different frequencies from GSM and does not make the same noise. When it drops to EDGE, the secific "GSM noise" is there. There is a very specfic issue related to GSM, and it's not the same with 3G. You can easily Google this if you're curious about it. A 3G phone (when in 3G mode) will not do the same thing. |
If the phone is transmitting radio frequencies, they can be picked up. Certain frequencies might not be attuned to your equipment (even things such as cable length can aid in receiving radio signals), but any time a phone transmits, there's a possibility that the transmission will be picked up.
Skylab
Reviewerus Prolificus
Quote:
Agree 100% with that of course - just pointing out that there is a specific problem with GSM and speakers (which would include headphone drivers) that goes well beyond normal RFI, and it makes that "machine gun" kind of sound described by the OP.
| Originally Posted by Uncle Erik /img/forum/go_quote.gif If the phone is transmitting radio frequencies, they can be picked up. Certain frequencies might not be attuned to your equipment (even things such as cable length can aid in receiving radio signals), but any time a phone transmits, there's a possibility that the transmission will be picked up. |
Agree 100% with that of course - just pointing out that there is a specific problem with GSM and speakers (which would include headphone drivers) that goes well beyond normal RFI, and it makes that "machine gun" kind of sound described by the OP.
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