Amp info in the JGO Guitar Gear section

[Christian Miller]

The big difference is that every part of the valve amp is replaceable, while the printed circuit boards are unique.

*you mean hand-wired I think? Some of the valve amps have PCBs, for example the mainline Fender Reissues and are correspondingly less easy to repair.

[sgosnell]

We fought wars with flintlock muskets, too, because that was all that was available. The drones taking out tanks in that unpleasantness near the European/Asian border don't use tubes. Every army in the world abandoned tubes as soon as transistors became available, because reliability lowers casualties. Tubes are only used in applications that don't require reliability. If your tube amp dies, you don't die, you can finish the gig with a backup solid state amp.

[Alter]

Yes, in the 60s, many amp components had military grade reliability, unlike today. That's why many old Fender amps still work fine, whereas current amp components, tubes etc fail after only a few years.

[John A.]

Yes, in the 60s, many amp components had military grade reliability, unlike today. That's why many old Fender amps still work fine, whereas current amp components, tubes etc fail after only a few years.

Except that a great many 60's amps have had many (if not most) of their components replaced multiple times over the years. It's common for basically nothing but the chassis and the transformers to be original in a vintage amp.

[Cavalier]

My 65 Gemini 1 has a newer reverb tube but that is it. My silver face twin has been retubed a couple times.
There are probably a fair amount of people replacing things they don't need to because they think they are supposed to. I've had these amps for decades and they are regularly used.

[Rickco]

JJ valves are made in Slovakia.

I stand corrected, JJvalves from Slovakia along with most modern manufacturers from Asia are very much hit and miss bottom line is its hard to find good tubes and I hate to say it if your under a certain age probably never heard one either. One of my favorite KT88s went south last nite as I was just getting ready to shut it down, it had been in the amp since the early '70s...shit!

[Doctor Jeff]

I will go back and read all the responses in detail, I promise.

I will be going down to 2 amps--an Epiphone Valve Jr., which is for me THE perfect living room tube amp; and a Fishman Artist, which I use for acoustics and would take to gigs if I had any gigs. The Artist is clean, clean, clean, but can take a pedal if needed. And loud and light.

Here's a question--what do jazz or jazz-adjacent musicians play with these days? I haven't seen a Fender Twin in like forever. Even the rock artists I see often play into a smaller tube amp that's miked or DI'd. Real working guitarists it seems don't necessarily feel that bigger is better.

[Litterick]

*you mean hand-wired I think? Some of the valve amps have PCBs, for example the mainline Fender Reissues and are correspondingly less easy to repair.

I was referring to the amps in the photos.

I have two hand-wired amps, and no others. I sleep easily, knowing they are not rotting away in the night.

[Cavalier]

I will go back and read all the responses in detail, I promise.

Here's a question--what do jazz or jazz-adjacent musicians play with these days? I haven't seen a Fender Twin in like forever. Even the rock artists I see often play into a smaller tube amp that's miked or DI'd. Real working guitarists it seems don't necessarily feel that bigger is better.

That is funny, it doesn't matter if you like forever or if you have lick fervor if you don't read the posts. Leg work pays,.lots of posts about what people use. It does make sense to have different rigs for different sized places. If I'm in any doubt about the room, PA, band volume I take the Twin because it has saved me from those occasions where there aren't enough inputs to the PA or it sounds terrible etc....

[yebdox]

Many good opinions expressed here, often with a depth of time and experience. Thank you!

Big tube fan here, but I don't gig much over the last few years. May finally pull the trigger on a Quilter head, as I stare at my 2 favorite amps, waiting silently for repair (don't worry, I have 4 other tube amps, including my Twin with Celestion 1265's), but the big issue for me is tube reliability and expense.

And, even though I, too, am slowing descending into geezerhood (turning 70 this summer), I'm grateful that years of regular, moderate weight training have left me still capable of easily moving a Twin out of the basement, into the back of the suv, up some stairs, etc. without causing any more harm than a spate of grumbling and strange looks from the dogs. For many, many reasons, strength training is a fabulous investment in one's future yielding many benefits, including the option of power tube amplification. It's literally never too late to invest in your physical strength, even if you are strictly in the solid state micro amp lane from here on out.

Putting a Twin or Super chassis into a custom built head cab and using head/cab combos is a great way to stay in the anti-geezer lane, although I'm not sure who to use at this point, as the famous cab builder, Larry Mather of Nashville, died a year or two ago, but there must be other builders out there.

Solid state, though significantly improved and surely with more progress to come, is still a tonal compromise for me, personally, but clearly, many great players still sound great with solid state. (Hey, I think I stumbled on some ad copy, or political slogan, there!).

Two of my biggest influences, however, Bernstein and Van Ruller, still seem to insist on tubes for their sound, and Kreisberg is mostly a tube believer. And don't get me started with the blues and fusion guys....Ford, Hinds, Scofield and Schofield, Henderson, so many others, insist on that as a necessary tone component. That's hard to miss for that kind of expressive tone and playing.

If you want a rig that sounds great in both realms, you may struggle (and still be fine) with making solid state work for both. Apparently, many of the touring pro sidemen rely on Kemper, etc for convenience, FOH control and balance, quick preset changes, but most I've read would still prefer tubes, if they had their druther.

Anyway, nice to have choices. Physical fitness, head/cab combos, dollies and perhaps a disabled parking permit can all contribute significantly to staving off geezerhood as long as possible.

And finally, if I may gently suggest to you all:

"Tubes rule, microchips drool!"

[DawgBone]

I stand corrected, JJvalves from Slovakia along with most modern manufacturers from Asia are very much hit and miss bottom line is its hard to find good tubes and I hate to say it if your under a certain age probably never heard one either. One of my favorite KT88s went south last nite as I was just getting ready to shut it down, it had been in the amp since the early '70s...shit!

I put 250-300 gigs plus about 150 rehearsals on my last set of JJ' 6L6's. A lot of those gigs were loud gigs. The tubes were still working fine when I replaced them though the plates had all turned white and they had kinda lost their luster tone-wise. JJ's are very reliable tubes IME and I have a set in a Twin now, along with some Tung-Sol's in my other Twin. I've never actually had a power tube failure.

[nevershouldhavesoldit]

I've never actually had a power tube failure.

My one and only was in the summer of 1964 in the middle of a gig - a 6L6 went belly up when I took it off standby after a break. I've carried spares ever since, and I've never needed one. My original '78 Boogie went over 30 years without a tube failure. I replaced them once at about 20 because I thought I should - but that was a waste of money.

The main reason tubes fail is abuse. Here's some general info that will help tube amp users keep their babies alive and healthy:

• Knocking an amp around is bad for tubes. As a general rule, the more gently you handle a tube amp, the longer the tubes will last and the more stable they will be.
  
  • The old saw about never touching the glass is most probably wrong, and many experts agree (e.g. this one). It will not harm tubes to touch them with your fingers unless you have some mighty nasty stuff on your hands.
  
  
• Bias voltage needs to be set correctly in amps that don't have auto-biasing. Bias that's out of the designated range for a given circuit will cause overheating. The telltale sign of this is cherry red plates, AKA "red plating". Cathode biased amps can need bias adjustment, especially those running class A/B (for which cathode biasing is not ideal - it's most stable in pure class A circuits).
• Overheating from any cause will shorten tube life and increase the risk of failure. There's a reason you see cooling fans in many top quality high powered tube amps (e.g. there was a Rotron "WhisperFan" in my 100W Boogie).
  
  • Tubes need air circulation to stay cool. This wasn't much of a problem in old school wide open back cabinets. But as partial back panels grew and there was less space into and through which air could flow by convection alone, operating temps rose.
  • Heat was a potential problem even when tubes sat in top mounted sockets on chassis that were in the bottom of the cabinet. The shift to hanging the tubes beneath a top mounted chassis was another factor in higher chassis, tube, and component temps. This made it even harder for circulating air to flow around the tubes, since hot air rises. Removing the back panel(s) from open back amps helped to let that hot air escape, but acooling fan was and still is one of the best things you can do for your tube amp.
  
  
• There's a lot of hype around standby switches, which interrupt high voltage to the power tube plates. It's true that hitting the tubes with high voltage when they're cold can cause damage to the cathode. What's not true is that the tubes we use are subject to this. Modern 6X6s, ELX4s etc are resistant to this and are not likely to suffer at all whether or not you use the standby switch. But prolonged periods (probably hours) during which the filaments are heated but there's no conduction through the tube can cause "cathode poisoning" whether the standby switch is on or off. From the Music ProductionGlossary":
  
  • "Cathode poisoning, in the context of vacuum tube amplifiers, is a phenomenon that can severely impact the performance and lifespan of the tube. It’s a result of chemical processes that occur at the cathode, which can lead to the deterioration of the tube’s performance over time. There are several forms of cathode poisoning, but one of the most detrimental to amplifiers is the growth of interface resistance. This phenomenon occurs when a vacuum tube’s cathode is fully heated, but no anode current is allowed to flow for extended periods (several hours). This might happen, for instance, if a tube amplifier is left powered on without being played for a long time.
    
    In such a situation, a high-resistance chemical layer can form between the actual metal cathode tube and the oxide coating on the cathode’s surface. This layer acts much like an unbypassed cathode resistor, leading to an increase in noise and a reduction in the useful gain of the tube. It’s as if a barrier has been created that impedes the efficient flow of electrons from the cathode, and as a result, the tube doesn’t perform as well as it should.
    
    Another form of cathode poisoning is the absorption of gas into the oxide coating of the cathode. Over time, gas molecules within the vacuum tube can become embedded in the cathode’s oxide coating, hindering its ability to emit electrons.
    
    What makes cathode poisoning particularly problematic is that once the high-resistance chemical layer is formed, it cannot be removed. So even though the oxide coating (which is responsible for emitting electrons) might still have plenty of life left in it, the tube’s overall performance will still be compromised. The best way to avoid cathode poisoning is to ensure that the vacuum tube is operated under proper conditions. This includes not leaving the amplifier powered on for extended periods without use, and making sure that the tubes are correctly biased to prevent undue strain on the cathode."

[garybaldy]

My one and only was in the summer of 1964 in the middle of a gig - a 6L6 went belly up when I took it off standby after a break. I've carried spares ever since, and I've never needed one. My original '78 Boogie went over 30 years without a tube failure. I replaced them once at about 20 because I thought I should - but that was a waste of money.

The main reason tubes fail is abuse. Here's some general info that will help tube amp users keep their babies alive and healthy:

• Knocking an amp around is bad for tubes. As a general rule, the more gently you handle a tube amp, the longer the tubes will last and the more stable they will be.
  
  • The old saw about never touching the glass is most probably wrong, and many experts agree (e.g. this one). It will not harm tubes to touch them with your fingers unless you have some mighty nasty stuff on your hands.
  
  
• Bias voltage needs to be set correctly in amps that don't have auto-biasing. Bias that's out of the designated range for a given circuit will cause overheating. The telltale sign of this is cherry red plates, AKA "red plating". Cathode biased amps can need bias adjustment, especially those running class A/B (for which cathode biasing is not ideal - it's most stable in pure class A circuits).
• Overheating from any cause will shorten tube life and increase the risk of failure. There's a reason you see cooling fans in many top quality high powered tube amps (e.g. there was a Rotron "WhisperFan" in my 100W Boogie).
  
  • Tubes need air circulation to stay cool. This wasn't much of a problem in old school wide open back cabinets. But as partial back panels grew and there was less space into and through which air could flow by convection alone, operating temps rose.
  • Heat was a potential problem even when tubes sat in top mounted sockets on chassis that were in the bottom of the cabinet. The shift to hanging the tubes beneath a top mounted chassis was another factor in higher chassis, tube, and component temps. This made it even harder for circulating air to flow around the tubes, since hot air rises. Removing the back panel(s) from open back amps helped to let that hot air escape, but acooling fan was and still is one of the best things you can do for your tube amp.
  
  
• There's a lot of hype around standby switches, which interrupt high voltage to the power tube plates. It's true that hitting the tubes with high voltage when they're cold can cause damage to the cathode. What's not true is that the tubes we use are subject to this. Modern 6X6s, ELX4s etc are resistant to this and are not likely to suffer at all whether or not you use the standby switch. But prolonged periods (probably hours) during which the filaments are heated but there's no conduction through the tube can cause "cathode poisoning" whether the standby switch is on or off. From the Music ProductionGlossary":
  
  • "Cathode poisoning, in the context of vacuum tube amplifiers, is a phenomenon that can severely impact the performance and lifespan of the tube. It’s a result of chemical processes that occur at the cathode, which can lead to the deterioration of the tube’s performance over time. There are several forms of cathode poisoning, but one of the most detrimental to amplifiers is the growth of interface resistance. This phenomenon occurs when a vacuum tube’s cathode is fully heated, but no anode current is allowed to flow for extended periods (several hours). This might happen, for instance, if a tube amplifier is left powered on without being played for a long time.
    
    In such a situation, a high-resistance chemical layer can form between the actual metal cathode tube and the oxide coating on the cathode’s surface. This layer acts much like an unbypassed cathode resistor, leading to an increase in noise and a reduction in the useful gain of the tube. It’s as if a barrier has been created that impedes the efficient flow of electrons from the cathode, and as a result, the tube doesn’t perform as well as it should.
    
    Another form of cathode poisoning is the absorption of gas into the oxide coating of the cathode. Over time, gas molecules within the vacuum tube can become embedded in the cathode’s oxide coating, hindering its ability to emit electrons.
    
    What makes cathode poisoning particularly problematic is that once the high-resistance chemical layer is formed, it cannot be removed. So even though the oxide coating (which is responsible for emitting electrons) might still have plenty of life left in it, the tube’s overall performance will still be compromised. The best way to avoid cathode poisoning is to ensure that the vacuum tube is operated under proper conditions. This includes not leaving the amplifier powered on for extended periods without use, and making sure that the tubes are correctly biased to prevent undue strain on the cathode."

Standby mode is not good in a break.

[nevershouldhavesoldit]

Standby mode is not good in a break.

AFAIK, there’s no evidence to support this. Cathode poisoning occurs when a tube is hot for hours with no signal passing through it, whether or not there’s plate voltage applied. Since the standby switch on most guitar amps turns plate voltage on and off, it has no effect. Leaving the amp on for hours with no signal applied is what causes cathode poisoning, whether the standby switch is on or off. If you have gigs with breaks that long, turn the amp off during them

Cathode stripping only happens at operating voltages above about 10kV. It’s a problem in RF transmitting tubes, not small signal audio tubes.

[garybaldy]

AFAIK, there’s no evidence to support this. Cathode poisoning occurs when a tube is hot for hours with no signal passing through it, whether or not there’s plate voltage applied. Since the standby switch turns plate voltage on and off, it has no effect.

Cathode stripping is only a problem with plate voltages over about 10kV. Our tubes are essentially immune. Stripping occurs when stray electrons from the cathode strike molecules of the tiny amount of gas present in every man made vacuum - no one has yet created a truly complete vacuum. The collision has to be powerful enough to knock off an electron. This creates a positively charged ion that then slams back onto the negatively charged cathode, damaging the surface.

Only if your breaks are hours long do you need to worry about this.

Since the early days when I had my first amps with standbys I religiously went through the standby ritual. In the last couple of years an old friend, guitar player and pickup winder suggested I read up on the so called pros and cons. The 'idea' that they are bad in guitar amps had been unbeknown to me all those years. We can all make up are own mind what we think from what we read. I've read the likes of what you are saying regarding the technical stuff and I've read contradictory stuff (I've read it all!). It all comes from experts in the field. I currently (sorry) turn my amp on and then immediately bypass the standby and to turn off, first standby mode then immediately mains off. I never leave it on standby for more than about 5 seconds. No probs so far. I may try leaving the standby off and just turn my amp on and off like I did with my AC30s.

[Tal_175]

It funny that general artificial intelligence is almost here yet we still don't have a definite answer to what standby switch on tube amps achieve. The analog world really needs to get it together.

[nevershouldhavesoldit]

Since the early days when I had my first amps with standbys I religiously went through the standby ritual. In the last couple of years an old friend, guitar player and pickup winder suggested I read up on the so called pros and cons. The 'idea' that they are bad in guitar amps had been unbeknown to me all those years. We can all make up are own mind what we think from what we read. I've read the likes of what you are saying regarding the technical stuff and I've read contradictory stuff (I've read it all!). It all comes from experts in the field. I currently (sorry) turn my amp on and then immediately bypass the standby and to turn off, first standby mode then immediately mains off. I never leave it on standby for more than about 5 seconds. No probs so far. I may try leaving the standby off and just turn my amp on and off like I did with my AC30s.

The most convincing fact for me is that there are no standby switches on any low voltage (ie plate voltages under 1 kV) tube powered equipment I’ve ever seen except for audio amplifiers. I’ve been using top quality lab equipment (B&K and HP scopes, rectifiers, signal generators etc) with SS rectification and tube circuitry for 60 years with no evidence of tube damage or shortened life. SS rectifiers hit the plates with their rated DC voltage on cold startup, and the equipment runs for many hours at a time. I trust B&K, H-P etc to have used standby switches if they served any purpose.

Fender is widely believed to have put standby switches in his amps as a service aid. What’s odd about that is that he put them after the PS caps to switch only DC to the plates. The charged caps are at least as dangerous to anyone working on an amp as the plate voltages. There are also known instances in which someone thought the amp was off because the SB switch was off so there was no output. Fender’s version of a SB switch isn’t exactly a safety aid.

Some amps put a standby switch on the signal path between preamp and power amp stages, so all it does is mute the amp.