Tube Watts vs. Solid State Watts - Any credence?

10-10-15: Bifwynne
Thanks Bombaywalla ... but what is the purpose of partial cathode coupling. Is it a form of local negative feedback?? Does it ameliorate some of the adverse affects associated with NFB that Ralph has written about, e.g., TIM distortion that raises the level of odd ordered harmonics??

ARC has used this type of topology for many years.

Search & you shall find!!! (this is note to self)
Look what I found:
* an article in Stereophile where the late William Z Johnson was interviewed by John Atkinson. WZJ talks a wee bit about partial cathode coupling & gives the credit to QUAD as the initial inventor since QUAD used it in their Quad30 amp some 30 yrs prior to that interview. See para #3 from the top:
http://cdn.stereophile.com/content/william-zane-johnson-1926%E2%80%932011#mX6ilT78dampubmG.97

* next, I found William Zane Johnson's patent application on the partial cathode coupling (must have been an enhancement of the Quad's version?). This is publication US3566236 A that was filed in 1968 & published in 1971. Yeah, you are correct - ARC has been using this for a long time in all their products.
http://www.google.com/patents/US3566236

You can read this stuff but here is the crux (cut & pasted from the patent application)
"Still another object of the invention is to provide an improved amplifier output stage coupling with partial cathode coupling, while maintaining classic tetrode operating parameters with substantially the same efficiency and drive requirements."

hope this provides some more insight, Bifwynne.

"Tube amps have no bass" seemingly doesn't address the countless tube bass amps like the amazing Ampeg SVT that's been around since 1969…Mesa made an astonishing sounding tube head in 1983 or something that a dude in my band back then used. Also note that tube hifi watts have been proven in many scientific studies using sine waves, pink noise, grunge music, various speaker loads, various bong loads, yo mama, and luddite resistors to illustrate the fact that tube watts are more fun. My Jolida 502p sounds best using the 4 ohm tap…it's a fave. Another note about tubes…the Woodstock ('69) sound was powered by piles of McIntosh tube amps under the stage, a fact I recently discovered that makes me happy.

Thanks Bombaywalla. I really enjoyed reading the 1983 Atkinson and Messenger interview of Mr. Johnson. It was like taking a trip back in time.

IMO, since that time, ARC has made many significant refinements to their technology that have taken its product line many level beyond where ARC was holding back in 1983.

Wish I could say I understood the patent app stuff ... but I didn't. I'm not a EE.

I think Mr. Johnson wisely commented that trying to judge the quality of an amp by throwing around cold stats like slew rate, phase angle shift, bandwidth, and so forth is a fool's errand. It made perfect sense to me when he said many technical factors are taken into consideration when designing an amp that sounds good. To even think that a perfect amp can be viewed as "gain on a wire" is an absurdity.

Thanks again.

well some of them isn't most of them. it's nature of tubes and output transformers. they're weak when impedance of speaker goes down on low frequencies.

Some actually think that only tubes can make the bass sound right. Or at the vey least something like Lamm hybrids.
This is probably a slight exaggeration and a matter of taste and speaker choice, but I can see a strong point.