Fair comments Newbee.
I've owned ARC tube gear for almost 10 years. Perhaps I'm lucky, but the only maintenance issues I've experienced related to blown bias resisters. Fortunately, there's an ARC authorized service tech near my house who also happens to make house calls for a small extra fee.
Can't speak about other tube amp models, but I think ARC gear is extremely well built and dependable. So except for the periodic replacement of tubes and occasional bias adjustments, no problems.
Your point about electrical matching has been a vertical learning curve for me. For others who may be interested in tube gear, pull some of my more recent posts. I've raised most of the relevant questions. And our more tech knowledgeable and savvy members have explained in plain English most of the key issues and theory.
Let me at least respond to one point you just raised. It's true that electrical impedance matching between a tube amp and speakers is a key consideration. Having said that, at least ARC uses some local negative feedback (partial cathode follower) to achieve low'ish output impedance.
For example, in the case of my amp, the ARC Ref 150, output impedance off the 4 ohm taps is just .55 ohms; and 1.1 ohms off the 8ohm taps. That corresponds to relatively tight output voltage regulation: +/- .4 ohms off the 4 ohm taps; and about +/- .8 ohms off the 8 ohm taps.
What that means in plain English is that my tube amp can perform somewhat like a SS amp. According to Ralph Karsten's white paper, SS amps typically have very low output impedances and present a constant voltage source to the speakers, a/k/a Voltage Paradigm amps. They produce power by generating current, have high damping factors and tight voltage regulation.
So, going back to my example illustrating the ARC Ref 150, while not a true low output impedance, constant voltage source type amp, it performs somewhat like one. Hence, the Ref 150 may have greater utility in driving a wider range of speakers than a tube amp that has higher output impedance, a low damping factor and a wider range of output voltage regulation.
So ..., as Newbee says, a little more homework is needed when going the tube route.
Happy Holidays.
Bruce
I've owned ARC tube gear for almost 10 years. Perhaps I'm lucky, but the only maintenance issues I've experienced related to blown bias resisters. Fortunately, there's an ARC authorized service tech near my house who also happens to make house calls for a small extra fee.
Can't speak about other tube amp models, but I think ARC gear is extremely well built and dependable. So except for the periodic replacement of tubes and occasional bias adjustments, no problems.
Your point about electrical matching has been a vertical learning curve for me. For others who may be interested in tube gear, pull some of my more recent posts. I've raised most of the relevant questions. And our more tech knowledgeable and savvy members have explained in plain English most of the key issues and theory.
Let me at least respond to one point you just raised. It's true that electrical impedance matching between a tube amp and speakers is a key consideration. Having said that, at least ARC uses some local negative feedback (partial cathode follower) to achieve low'ish output impedance.
For example, in the case of my amp, the ARC Ref 150, output impedance off the 4 ohm taps is just .55 ohms; and 1.1 ohms off the 8ohm taps. That corresponds to relatively tight output voltage regulation: +/- .4 ohms off the 4 ohm taps; and about +/- .8 ohms off the 8 ohm taps.
What that means in plain English is that my tube amp can perform somewhat like a SS amp. According to Ralph Karsten's white paper, SS amps typically have very low output impedances and present a constant voltage source to the speakers, a/k/a Voltage Paradigm amps. They produce power by generating current, have high damping factors and tight voltage regulation.
So, going back to my example illustrating the ARC Ref 150, while not a true low output impedance, constant voltage source type amp, it performs somewhat like one. Hence, the Ref 150 may have greater utility in driving a wider range of speakers than a tube amp that has higher output impedance, a low damping factor and a wider range of output voltage regulation.
So ..., as Newbee says, a little more homework is needed when going the tube route.
Happy Holidays.
Bruce