Guitargonaut
Groovin' on a killer stump...
- Joined
- Oct 30, 2016
- Messages
- 20
Is anyone else experiencing this? I'm only using NOS tubes. I'm averaging a tube a year in the PI position of my Archon.
Archon 50 hard on PI tubes.
- Thread starter Guitargonaut
- Start date
D
Deleted member 5962
Guest
I bought mine used and am going on 2 years on a non-NOS tube that came with it. Don’t open it up often, which I realize would make a big difference.
elvis
Hamfisted String Banger
Gigged my 100 relentlessly. No issues.
elvis
Hamfisted String Banger
What is the actual symptom? Non functional, or not sounding quite how you want?
Guitargonaut
Groovin' on a killer stump...
- Joined
- Oct 30, 2016
- Messages
- 20
The first two went microphonic, the third would have a muted output for the first minute(ish) after power-up, pop, then operate normally.
elvis
Hamfisted String Banger
Seems like a tube issue, not an amp issue. If the tubes wore out, that might seem more like an over stress sort of thing. Microphones come from tube design and manufacturing. Also can come from vibration, like you might get running a Combo loud or a head on top of a cabinet loud.
All tubes are microphonic to a degree, but as Elvis notes, problem microphonics are mostly a mechanical problem caused or exacerbated by physical vibration.
In other words, the tube is picking up speaker vibration. Combo amps are notorious for this, because the speakers are literally next to the tubes, but even heads sitting on a cabinet are going to pick up the cabinets vibrations from the speakers.
In other words, 99.9% of the time, it ain’t the amp that’s the issue, it’s the tube. Changing tubes once a year is pretty common with lots of amp owners, though preamp tubes usually last longer.
Is your Archon a head or combo?
In other words, the tube is picking up speaker vibration. Combo amps are notorious for this, because the speakers are literally next to the tubes, but even heads sitting on a cabinet are going to pick up the cabinets vibrations from the speakers.
In other words, 99.9% of the time, it ain’t the amp that’s the issue, it’s the tube. Changing tubes once a year is pretty common with lots of amp owners, though preamp tubes usually last longer.
Is your Archon a head or combo?
Guitargonaut
Groovin' on a killer stump...
- Joined
- Oct 30, 2016
- Messages
- 20
Archon 50 Head - I learned my lesson about combos and microphonics a long time ago.
Having 30+ years experience owning tube amps I'm familiar with the intricacies of ownership and maintenance. I've seen NOS and NS tubes do some interesting things during that period. I'm assuming the PI is the tube closest to the power tubes. I also realize coincidence can play a part as well. I was just wondering if anyone else was experiencing the same issue.
The two tubes that went microphonic were JAN GE 12AX7s while the tube that "failed" was an Amperex 12AX7. The reason I put the word failed in quotation marks was because when I tested the tubes from the amp while trying to find the problem - the Amperex tested as good but incredibly high as far as gain on my VT-1000. Most 12AX7s test in the 8-10 range but the Amperex tested at 15. Way back when - when I first got the VT-1000 - the Amperex tested at a 9 for both triodes. That tells me something went wrong within the tube. The other tubes tested had the same ratings as when they were first tested about a year and a half ago. I didn't have the VT-1000 when the JAN GEs went microphonic so there's no way for me to do a comparison. (out of curiosity more or less) Disclaimer - the VT-1000 isn't the best tube tester out there but it serves a basic need.
The JAN GEs are a fairly robust tube and those that have given me issues always seemed to go microphonic at some point instead of outright failure - regardless of the amp. I'm hoping it's just coincidence because it was a different brand tube that failed and tubes tend to be unpredictable. Time will tell.
Seeing as to how others aren't experiencing the same problem - I'll keep an eye on things, try a different brand, etc.
Having 30+ years experience owning tube amps I'm familiar with the intricacies of ownership and maintenance. I've seen NOS and NS tubes do some interesting things during that period. I'm assuming the PI is the tube closest to the power tubes. I also realize coincidence can play a part as well. I was just wondering if anyone else was experiencing the same issue.
The two tubes that went microphonic were JAN GE 12AX7s while the tube that "failed" was an Amperex 12AX7. The reason I put the word failed in quotation marks was because when I tested the tubes from the amp while trying to find the problem - the Amperex tested as good but incredibly high as far as gain on my VT-1000. Most 12AX7s test in the 8-10 range but the Amperex tested at 15. Way back when - when I first got the VT-1000 - the Amperex tested at a 9 for both triodes. That tells me something went wrong within the tube. The other tubes tested had the same ratings as when they were first tested about a year and a half ago. I didn't have the VT-1000 when the JAN GEs went microphonic so there's no way for me to do a comparison. (out of curiosity more or less) Disclaimer - the VT-1000 isn't the best tube tester out there but it serves a basic need.
The JAN GEs are a fairly robust tube and those that have given me issues always seemed to go microphonic at some point instead of outright failure - regardless of the amp. I'm hoping it's just coincidence because it was a different brand tube that failed and tubes tend to be unpredictable. Time will tell.
Seeing as to how others aren't experiencing the same problem - I'll keep an eye on things, try a different brand, etc.
SteelHorse
New Member
- Joined
- Jan 8, 2015
- Messages
- 84
PI is not a notorious position for being hard on tubes. But I don’t run NOS in my PI as i had an amp cook the factory PI. Had it then turn two NOS microphonic. I run Sovtek 12AX7LPS in my PI positions now and could not be happier.
The Cathode Follower is notorious for cooking tubes in some amps. You want a robust tube in a CF position.
The Cathode Follower is notorious for cooking tubes in some amps. You want a robust tube in a CF position.
Last edited:
elvis
Hamfisted String Banger
The PI has to drive the power tubes. An amp design may run it at high volts and dissipate more power in the PI, burning it out sooner. Or it may run enough volts to damage any tube that is not OK with plate voltage near the reliability limit.
NOS may be built more consistently, or may be part of test selected high reliability populations. They may also be part of the test rejects. Note that the tube tester you use will check gain, but not max voltage or other reliability parameters. Tubes may be really good From a signal perspective but built to a lower plate voltage spec. Not every tube is a direct replacement in every way.
For followers, many amps use a higher plate voltage than some brands of tube can stand. This has become more common with the New Sensor brands.
In any case, be careful with NOS. They are not magical and they are often $$$. Choose your applications well. Check the absolute maximum specs of different NOS tube brands and models. Don’t rely on the general purpose 12ax7 datasheet.
NOS may be built more consistently, or may be part of test selected high reliability populations. They may also be part of the test rejects. Note that the tube tester you use will check gain, but not max voltage or other reliability parameters. Tubes may be really good From a signal perspective but built to a lower plate voltage spec. Not every tube is a direct replacement in every way.
For followers, many amps use a higher plate voltage than some brands of tube can stand. This has become more common with the New Sensor brands.
In any case, be careful with NOS. They are not magical and they are often $$$. Choose your applications well. Check the absolute maximum specs of different NOS tube brands and models. Don’t rely on the general purpose 12ax7 datasheet.
You’re like me, then; an NOS tube person. I didn’t realize you were very experienced with tube amps.
I’ve had great luck with the JAN GE 12 AX7s. I retubed a Mesa Lone Star with them, and it improved the amp, as NOS usually does IMHO. I think they’re pretty consistently good, so who knows?
I have had less good luck with NOS Brimar tubes. One was bad out of the box, and one in my DG30 went south pretty quickly. But the rest have been rock solid for 5 years.
My HXDA has NOS Mullards in the preamp section, and NOS Siemens in the power section. I had one Siemens get a little noisy last year, but I have a few sets, so it wasn’t a big deal.
Once the cabinet I ordered for my Fillmore comes, I have a set of NOS RCAs and JAN GEs to install in it. I’m still thinking about which power tubes I’ll install, and am leaning towards Sylvanias.
Whatever the cause, I hope you get your amp issue sorted.
Guitargonaut
Groovin' on a killer stump...
- Joined
- Oct 30, 2016
- Messages
- 20
Thanks for all the replies. I'll keep an eye on things and keep you posted.
The Dragonator
New Member
- Joined
- Feb 21, 2020
- Messages
- 25
I can't comment on the Archon use of tubes, but I can speak for decades of many tube amps used by me and others, and how long we had our tubes last.
First, great or even good preamp tubes can and should last for years, even cascade setups. I have friends playing pro who haven't had a preamp tube issue in a decade or more. Yeah, a rare one can go microphonic for no apparent reason, but at the voltages these tubes operate at, if you are having to change them out a lot there is something very wrong. Example -- I have this one beastly heavy Pro Tube Twin, on wheels thankfully, been across the US twice, bought in 2006 I think, put in some extra spec from Tube Dr in V1 and in another socket when bought. I have not needed to change any since. No issues.
Power Tubes? Rule of thumb is, if you gig hard with the amp, new power tubes needed every 6 to 9 months, depending how loud you play.
Bedroom use for power tubes at medium to low levels, you should get at least 2 years out of a set. Loud amp in your living room, at least 1 year.
I have used most of the popular brands, don't bother with NOS, and aside from some tonal differences, I find they are all about the same in lifespan and quality. Oh, I I run my power tubes only ever so slightly hot but not frying them.
First, great or even good preamp tubes can and should last for years, even cascade setups. I have friends playing pro who haven't had a preamp tube issue in a decade or more. Yeah, a rare one can go microphonic for no apparent reason, but at the voltages these tubes operate at, if you are having to change them out a lot there is something very wrong. Example -- I have this one beastly heavy Pro Tube Twin, on wheels thankfully, been across the US twice, bought in 2006 I think, put in some extra spec from Tube Dr in V1 and in another socket when bought. I have not needed to change any since. No issues.
Power Tubes? Rule of thumb is, if you gig hard with the amp, new power tubes needed every 6 to 9 months, depending how loud you play.
Bedroom use for power tubes at medium to low levels, you should get at least 2 years out of a set. Loud amp in your living room, at least 1 year.
I have used most of the popular brands, don't bother with NOS, and aside from some tonal differences, I find they are all about the same in lifespan and quality. Oh, I I run my power tubes only ever so slightly hot but not frying them.
