by bordonbert Thu Mar 16, 2023 1:56 am
Yes the amp will take that punishment all night long. People worry because the top of the enclosure gets hot to the hand. Hot to the hand as in, just short of actual pain, is only around 45-50degC. If you can keep your hand on the top for a few seconds before you have to take it off then you are running at about that. Components will live a long long time at those temperatures - despite what the internet will tell you.
I always check my estimating from the actual datasheets and the known theory surrounding them. For example, those nasty electrolytics which the internet tells you you need to change out every couple of years have working life projections of many thousands of hours in use with 8,000hrs being a reasonably common starting figure. For standard spec caps that is usually specified at 85degC. Arrhenius Law tells us that their lifetime will double for every 10degC they work at below that. So if you can keep the temperature down to 55degC for most of their working life, that is 3x10degC below 85degC, you have increased their lifespan by 2x2x2 which is 8x. And for better quality electrolytics to military spec they are specified at 105degC which increases it even more. But the internet tells you to swap out your major caps from between 6months to 2 years "just in case". None of that swap out frenzy makes sense to engineers.
Let me ask you where did you learn that valves wear out more quickly through heavier (louder) use? This is really a common internet myth. Yes valves will wear out but it isn't just high levels of signal which do that. It is more abuse and pushing them beyond their stated maximums in many areas. Using them the way we do is not particularly stressful for a valve. Preamp valves especially live for many many years before eventually going soft. I have some in my 1968 Marshall SL100 which are still originals and working fine. I know they are genuine originals because I have owned it since 1969. The real expertise in valve knowledge without the surrounding hype was around the 40s/50s/60s. That's when books like the Radiotronics and Mullard Handbooks were in print. None of them would see any need to swap out valves in such short periods. The class of valve which we use in our amps is a "radio receiving" type. These were the valve which were lying around and cheap to buy when the first guitar amps were designed. There is nothing special about them in the way we use them, they were just convenient and to hand. They are not quickly "worn out" by using them at high volumes. Much more damage is done by simply using the common design of Standby, (fortunately not the H&K circuit), and this is well documented.
Don't take my word for it, I know my pushing this sort of info is not liked by most guitarists. They prefer to live in a state of awe towards their guru tech who knows everything there is to know about guitar amps. We-e-e-ell, that's a bit of a stretch in reality. Here is a link to an old school genuine expert in valve technology.
The Valve Wizard His site will have anything you would want to know about valves. It is highly technical for the most part, much more than a guitarist would need, but it has some really interesting reading if you scan. Take a look at his page on "Power And Standby Switches" to see what sort of thing really kills valves. And most experts are completely in denial about the use of the Standby though the theory behind it is well documented and sound, yet I still have to be made aware by any of them what process is the cause of this short term valve death in normal use!
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