atma-sphere
Who makes the highest quality tube amps?
One scale of 1-10, 10 being best designed and constructed technically, personal sound preferences aside, who are the 8s, 9s, and 10s?
VAC, ARC, Atmasphere would seem like likely candidates I can think of. Are they ?
Where does Decware rank? Rogue? How about others?
SOme technical facts to help support any claims is appreciated please.
Durability and reliability matters to me here as much as anything. I would want my tube gear to continue to work as reliably as designed years down the road as well as up front.
THanks.
Thanks.
VAC, ARC, Atmasphere would seem like likely candidates I can think of. Are they ?
Where does Decware rank? Rogue? How about others?
SOme technical facts to help support any claims is appreciated please.
Durability and reliability matters to me here as much as anything. I would want my tube gear to continue to work as reliably as designed years down the road as well as up front.
THanks.
Thanks.
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- 81 posts total
All tube OTL amplifiers use SEPP, cyclotron or Mr. Futterman’s variations. All these are push-pull amplification stages. They can claim single ended, but they are push pull topologies. Feedback is mandatory in this designs to cancel out the artifacts generated by the problems of not true complimentary driving of the signal, and of course cross-over distortion. Some clever variations have been presented on the market during recent years, but they are nevertheless push pull topologies with many dbs of negative feedback, some of them use up to 60db of degenerative feedback. Of course, these amplifiers are not Class A devices.@believehifi Just so you know, the statements in the post above are mostly false. Here's why: There are in fact single-ended OTLs (which don't make much power) and they are **not** push pull. Here's one:https://www.transcendentsound.com/mini-beast.html We don't use feedback in most of our amps (MA-1, MA-2 and MA-3) and those that do use it run only 2-4 db. Even then we have customers that have us add a switch so they can switch it out which is no problem. We rely on other methods to minimize distortion; this is in order to keep higher ordered harmonics at bay because the ear is so sensitive to higher ordered harmonics. I can't speak for others, but in our case we have a completely symmetrical design and don't have the need for complementary output devices. We do that through the use of the Circlotron, and were the first manufacturer to use that circuit after EV discontinued its use in the 1950s. For several decades we were the *only* manufacturer using it. 60 db of 'degenerative feedback' sounds impossible to me (I suspect you are referring to loop feedback??). Can you provide a link? And finally, we can and do build our amps to be class A (A2, to be specific). The class of operation is somewhat load specific; a higher load impedance is needed on the smaller amps to remain in the class A region. We don't have crossover distortion problems since we don't employ an output transformer and we paid special attention to making sure that every part of the amp (voltage amplifier, driver and output section; there is no dedicated phase splitter) have operating points that simply prevent any sort of crossover issue. As a result, distortion linearly decreases to unmeasurable as the power level is decreased. Usually the only kind of amp that can do that is single-ended. I own Dyna. I go with Dyna. So did old man Johnson of ARC, who copied Dyna. (RIP) And others.Bill Johnson modified Dynaco amps (the ST-70 that ARC had on display in their museum was recently sold) but he didn't copy them (the ARC ST-70 used a driver circuit that had a lot of balanced circuits in it). He did also use the Dynaco output transformer in the D-50, D-51, D-75 and a few others, which adds to the confusion. |
- 81 posts total