41–50 of 75 posts
I had a 1971 Marshall tube amp land in my lap, for free. I'm not a guitar player, but wanted to get it fixed it up before either selling it or learning guitar. There's a lot of "magic" there - the amp guy asked if I wanted to swap the tubes for some "more authentic" tubes that were used in England at the time. Pro tip - don't ask the internet for advice for making your tube amp sound nice, you'll get every opinion po…
I'd like to plug the YouTube Video by Jim Lill - "Tested: Where Does The Tone Come From In A Guitar Amplifier?" https://www.youtube.com/watch?v=wcBEOcPtlYk
The delivery style gets to some people (i.e. “I’m not ___ I just play guitar…”) but i find it absolutely fine.
I moved on from tube amps about 15 years ago and now really enjoy a variety of different solid state amplification stages with varying EQ and ‘dirt’ options at various places. Turns out a lot like were Jim’s Video goes.
> 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 :)
I 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?
Or do you mean why people who do period-authentic tube amps don't use SMPS? That's because tube-based SMPS is very complex, often as complex as amplifier itself, and needs unusual parts [1].
[0] https://www.sweetwater.com/store/detail/MicroTerror--orange-...
[1] https://www.righto.com/2018/09/glowing-mercury-thyratrons-in...
I 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?
Tangential 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.
Gives overview equations for MOSFET device simulations which are probably sufficient for most purposes in Section 3.5, and COMPLETE mathematical descriptions of the SPICE MOSFET implementation in Appendix A.3. Not for the weak.
Earlier quoted context omitted.
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?
I noticed the same thing. Like, why not at least use a fullwave rectifier with semiconductor diodes? Surely nobody believes that a tube diode in the power supply makes any audible difference.
There are quite a few effects like this. In a modern design this would be eliminated, but sometimes “bad” is good :)
Earlier quoted context omitted.
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?
I noticed the same thing. Like, why not at least use a fullwave rectifier with semiconductor diodes? Surely nobody believes that a tube diode in the power supply makes any audible difference.