Solving A 21st Century Problem (non-PRS content)

[Tucson Thump]

I've been having my amp collection gone over by my tech. I had picked up the 1958 Gibson GA-40 Les Paul amp after service and suddenly started having pops and static, and while I thought it was a tube I replaced all of them but still had the problem. Finally I took it back over and explained the problem. We plugged in the amp there and it was as quiet as could be so I left it there. Tonight, four days later, he sent me a text saying that it had finally started making some noise. The V1 and V2 preamp tubes are 5879 Pentodes which are very sensitive tubes. It turns out that the second channel inputs weren't shielded and the amp was picking up digital EMI/RFI from my 5G phone and our router in the next room to where I had the amp. I never thought of that since the amp was plugged into a Furman strip. A little bit of shielding and the amp is quiet.

No other amp I know of uses 5879 tubes (matter of fact I think only this third version of the GA-40 uses them) but I thought I would post this experience so that if someone has a preamp tube that has become microphonic they might benefit from knowing that 21st century technology is causing the noises they hear.

 

[jxe]

5g also causes cancer and willful ignorance.

 

[JasonE]

My amps don't use those tubes but I can tell you that at a gig once I set my phone on top of my amp and it was not a good experience. It made some horrible noises when the phone would communicate with the tower. I have seen other guys make that same mistake. I have not had any issues with the WIFI in the venues I have played in buy putting the phone directly on top of the amp definitely caused many noises you don't want to hear coming from your amp.

 

[WEDGE]

I saw Dokken at the Monsters of Rock tour years ago and through most of their set you could hear the Tampa airport tower through his rig. Supposed it was from his wireless setup.

 

[JasonE]

I saw Dokken at the Monsters of Rock tour years ago and through most of their set you could hear the Tampa airport tower through his rig. Supposed it was from his wireless setup.

That is entirely possible. I had a Nady wireless years ago (don't remember if it was VHF or UHF) that during a gig I had a trucker on his CB come through. That was quite a shock because when he came through my amp, it was loud.

 

[Deleted member 5962]

That is entirely possible. I had a Nady wireless years ago (don't remember if it was VHF or UHF) that during a gig I had a trucker on his CB come through. That was quite a shock because when he came through my amp, it was loud.

I didn't know what truckers said on their CB's so naturally I asked the forum expert, @ScottR I just wanted to make sure he gets full credit for this, as I certainly couldn't do it on my own...

"Breaker 1-9, breaker 1-9. This is Snowman. Come in Bandit."

 

[László]

The Divided by 13 FTR 37 also uses one 5879 tube.

 

[Alnus Rubra]

I didn't know what truckers said on their CB's so naturally I asked the forum expert, @ScottR I just wanted to make sure he gets full credit for this, as I certainly couldn't do it on my own...

"Breaker 1-9, breaker 1-9. This is Speedo Bandit."

 

[Tucson Thump]

The Divided by 13 FTR 37 also uses one 5879 tube.

I had heard that but had forgotten. I wonder which tubes they use, as there seems to be a sound difference between the NOS tubes available.

 

[László]

I had heard that but had forgotten. I wonder which tubes they use, as there seems to be a sound difference between the NOS tubes available.

Beats me!

 

[alantig]

I didn't know what truckers said on their CB's so naturally I asked the forum expert, @ScottR I just wanted to make sure he gets full credit for this, as I certainly couldn't do it on my own...

"Breaker 1-9, breaker 1-9. This is Snowman. Come in Bandit."

"Bandit, you sumbitch...."

 

[shinksma]

I saw Dokken at the Monsters of Rock tour years ago and through most of their set you could hear the Tampa airport tower through his rig. Supposed it was from his wireless setup.

Yep, VHF and UHF (analog) wireless systems are notorious for picking up external signals, as demonstrated in Spinal Tap's moment when playing the Air Base. Military & even commercial aircraft radios don't care about trying to lower signal strength - they are designed such that no matter what, that signal is getting through!

That's part of the reason I use digital wireless. Anther reason is that the digital systems generally work or don't, vs analog which noisily fade or get other RF interference a bit too easily.

Also, those older VHF/UHF units might be using freqs that are now allocated to some other use, and therefore use of the transmitters would be illegal under FCC or European-equivalent rules.

 

[JasonE]

Yep, VHF and UHF (analog) wireless systems are notorious for picking up external signals, as demonstrated in Spinal Tap's moment when playing the Air Base. Military & even commercial aircraft radios don't care about trying to lower signal strength - they are designed such that no matter what, that signal is getting through!

That's part of the reason I use digital wireless. Anther reason is that the digital systems generally work or don't, vs analog which noisily fade or get other RF interference a bit too easily.

Also, those older VHF/UHF units might be using freqs that are now allocated to some other use, and therefore use of the transmitters would be illegal under FCC or European-equivalent rules.

This is why I am a huge fan of the Sennheiser wireless units for UHF. They use a PL tone (They call it something different but in the HAM radio world it is a PL tone.) to help filter out other transmissions. I have had good luck with those.