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Greetings All,I'm a relative noob to tubes. I have a Herron VTPH-1 phono amp. I've had it for about 5 years. Recently the right channel developed a white noise rumble. I figured it was a tube and emailed the manufacturer who told me which one it was and had a section of his website that covered where/wht tubes to get.
So my question is more for the future. I assume if the left channel developed the same rumble I could figure which tube to change. But I don't know what what other symptoms would indicated problems with the other tubes. There are 4 12AX7W A/B, and one 12AT7WC. I imagine the 12ax7s are for RIAA correction and gain, not sure what the lone 12at7 does. But I don't know what I'm talking about. When it comes to electronics I am like a green belt in Karate, I know just enough to get my ass kicked.
Edit: Just FYI, I went ahead and bought a replacement set of tubes.
Nate
You can't cheat an honest man, never give a sucker an even break or smarten up a chump -- W.C. Fields
Edits: 04/06/21Follow Ups:
You also should determine how the RIAA cure is implemented - Active or Passive?
If it is active, then as the gain falls (as the tube ages the gain will be reduced) the eq will change , this will be harder to detect /measure...
if you have a passive EQ, then as the gain fails, the eq will not change, but if you are using lower output cartridges there will be a noticeable reduction in 'volume'...
Happy Listening
make sure you buy extra tubes for whatever you have. If something is noisy pull one tube at a time and replace it with a known good tube. If you think you found the one put it back in to verify because it could be oxidation on the pins or socket.
It's a pita that all tube lovers have done since the dawn of civilization. If there is no conclusion then it's something in the circuit
Ptolomy Almagest
Good idea on the deoxit, I figured the tubes would have lasted longer. I've had it for about 5 years but it has had a very inoffensive existence, and Heron Audio is careful to not drive the tubes very hard. But, I also bought a complete replacement set which arrives today. So hopefully it will be solved today!.
You can't cheat an honest man, never give a sucker an even break or smarten up a chump -- W.C. Fields
This maintenance guide can be found in the FAQ at the top of the Tube Asylum Page. Reading it will save you a lot of grief(and $$$)
It sucks to get old. It really sucks to get old and bitter.
Excellent resource, thank you!
You can't cheat an honest man, never give a sucker an even break or smarten up a chump -- W.C. Fields
You made the proper decision.
Thanks! I knew this would happen eventually.
You can't cheat an honest man, never give a sucker an even break or smarten up a chump -- W.C. Fields
If you know which tubes are for L/R channels, I would swap them over one at a time. If the noise carries over to the other channel then you've found the offending tube.
Only way to know if the tubes are 'good' is to test them with a tube tester, unless your pre gives indication of a failing tube. However if you don't have access to one, if all sounds okay then leave them be. I've had the same 12AX7's in my DAC for decades - pulled and tested them recently and both are still good.
"Only way to know if the tubes are 'good' is to test them with a tube tester"
Only problem with that is that most tube testers do not test for noise. A tube can test strong, and be noisy.
nt
nt
Thanks, I'm certain it is contained in the phono amp and I'm certain it is the right channel. I've been able to troubleshoot that far. The manufacturer told me which tube to replace but it got me thinking how would I know which to to replace if the symptoms were different. I guess swapping them out one by one would be an effective poor man's solution.
Nate
You can't cheat an honest man, never give a sucker an even break or smarten up a chump -- W.C. Fields
From what I see on the web, once you get inside the unit you'll see left and right markings next to the trim pots for the respective channel. Looks like V1 and V3 are left channel 1st and 2nd gain stages. V2 and V4 are right channel. V5 is the output tube for both. Looks like there is also some discussion on the Asylum if you did a search. Fine looking phono pre!Cheers!
Jonesy
"I know just enough to get into trouble. But not enough to get out of it."
Edits: 04/07/21
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