I'd like to plug the YouTube Video by Jim Lill - "Tested: Where Does The Tone Come From In A Guitar Amplifier?"
How Tube Amplifiers Work
31–40 of 75 posts
Re: How Tube Amplifiers Work
#32> WARNING: A tube amplifier chassis contains lethal high voltage even when unplugged--sometimes over 700 volts AC and 500 volts DC.
I promise you it does not contain AC when unplugged :)
Re: How Tube Amplifiers Work
#33I was a tube amp tech for several years, have built multiple guitar amps from scratch, and still dabble in it.
What may not be obvious is that modern tube amp designs are an evolutionary branch from 1930's technology, with only a little coming across from the transistor->digital tech tree. The amps of the 40s and 50s were pretty closely based on reference designs that came from RCA and other tube manufacturers.
Modern passive components (resistors, diodes and caps) are made to a far higher tolerance and are better understood, but tubes and transformers are a mixed bag. The older designs were somewhat overbuilt and can be more reliable or have tonal characteristics that are not available in modern parts.
Re: How Tube Amplifiers Work
#34This is an interesting topic, but the ads overlaying the content make this very hard to read :( * Please don't suggest I install an Ad blocker.
OK, have your {dad|fifth grader|IT manager} install an ad blocker.
Re: How Tube Amplifiers Work
#35This is an interesting topic, but the ads overlaying the content make this very hard to read :( * Please don't suggest I install an Ad blocker.
Firefox Reader View is really great. Worth giving a try if you use Firefox.
Re: How Tube Amplifiers Work
#36Excellent website, I'm an electrical engineer by trade, and play guitar. Back in college tube amps were long, long gone for anything other than microwave engineering.
My first real amp was a JCM800 2203 (technically a JMP "Mk 2 master model", which is just a cascaded JMP/Plexi, which Marshall then later re-released as JCM800 when their export deal expired...but I digress), and when I got into modding this website was my first real encounter with easy explained guides of the circuits.
Re: How Tube Amplifiers Work
#37I was a tube amp tech for several years, have built multiple guitar amps from scratch, and still dabble in it. What may not be obvious is that modern tube amp designs are an evolutionary branch from 1930's technology, with only a little coming across from the transistor->digital tech tree. The amps of the 40s and 50s were pretty closely based on reference designs that came from RCA and other tube manufacturers. Moder…
I always found fascinating the power section of valve amp for guitar will always be made of a very basic rectifier circuit to convert AC to DC that requires a expensive transformer and produce power with a terrible efficiency compared to more modern SMPS. Why is it nobody interested in valve amp never go the SMPS path? Is it all because sag is a desirable sound distortion?
Re: How Tube Amplifiers Work
#38very good article! i am surprised how such simple circuit was used in the 5f1!
Re: How Tube Amplifiers Work
#39Tangential question: Does anyone know of a basic large-signal equation for a triode (or any other vacuum tube type) like the simplified Ebers-Moll equation for BJTs or the square law equations for the linear and saturation regions of a MOSFET? It would really help my understanding, but whenever I google it I only see academic papers, like it's a weird thing to search for.
The Koren equations are the only thing I've found. "Improved vacuum tube models for SPICE simulations" https://normankoren.com/Audio/Tubemodspice_article.html The intractability of the Triode is part of the reason why the Pentode exists. And, you will note, the Pentode curves in certain modes looks a lot like your bog standard MOSFET. This also discusses how the "constants" ... well, aren't. https://www.john-a-harper…
That’s exactly what I’m looking for! Thank you very much!
Re: How Tube Amplifiers Work
#40Echoes of vacuum tubes in my memories: seeing tube testers in drug stores as a child (thinking they looked like either scientific equipment or else science-fiction props—and accidentally left just feet from the penny-candy), as well as peering into the back of our small B&W TV growing up (and marveling at the "city of light" inside there: all the orange glowing filaments from the tubes…). And gone by the time I was o…
>Anyone that likes to tinker in electronics I recommend they try their hand at at least one tube project (probably an amp of some kind).
Only if they are aware of the voltages and current often associated with tube setups. One bad move can be painful, or fatal in some cases.
I used to work on guitar amplifiers, doing modifications on tube amps. Messing around with the internals demanded my focus, a level of attention most "tinkerers" aren't likely ready for. Not trying to gatekeep here, just suggesting it may not be something for "anyone that likes to tinker".