Originally Posted by firev1
Are we talking tube vs transistor or about impedance issues, I really don't know where this is going. Anyways I'm not answering as I can't verify any of those claims made, nor trust the word of a single company who sells tube amps without any watermarked graphs or proof.
This thread was originally started by Germanium to discuss (I think):
- Output Transformerless Vacuum Tube power amps
- low damping factors
- high output impedances
- zero feedback
- Class A operation
- mechanically damped loudspeakers (I think)
I agree, the Atma-sphere link is mostly unsubstantiated marketing fluff. The designers (like Jack) really seem to know what they are doing. Lik most audiophile marketing groups, they cloud the issue with obscurant articles.
Originally Posted by germanium
Many of the lower end Martin Logan speakers sound sick with the tipical amps used with them. Unfortunately I don't think that my friends tube amp would help them much as there is way too much discontinuity between the woofer & the electrostat panel with these. The lower end Martin Logans have builtin dynamic woofers & to my ears sound horrible at best with any amp driving them it seems. They look nice but to me that is where the nice ends.
High damping factors also waste power as power is used in the proccess of choking (braking) the driver This power comes from somewhere & that somewhere is the power supply of the amp. Zero feed back tube amps don't waste power trying to brake the speaker hence they play louder for a given wattage rating. Whie this does work against them with cirtain speaker designs that were designed with high damping factors in mind (acoustic suspension speakers in particularwith total Q's greater than .707 which most are) it works very well with most other speaker designs Horns, electrostats, many ported speaker designs & ribbons all benefit from low to zero feedback tube designs which have low damping factors.
Thanks for the tip, on garbage day I will throwing out my lower end Martin Logans.
BTW, I my opinion, they sound better with a solid state amp.
I used to use an Output Transformer Coupled vacuum tube power amp with a cascode differential pair input stage, I thought that amp and the MLs sounded sick. Just my opinion.
Mathematically, a high output impedance power amp is less electrically efficient than a low output impedance amp.
Originally Posted by xnor
Which is a limitation.
Nope, tubes waste a lot of power.
(Emphasis by me.)
Nope, has nothing to do with tubes. You don't need tubes for low feedback, nor for high output impedance.
Also, besides being inefficient, tubes are bigger, less rugged, require periodic replacement ...
I gotta agree with all of what you say except the part about rugged.
Not too sure if I have ever seen a tube power amp with short circuit protection, but I have seen a lot of solid state power amps with circuit limiting protection.
Generally speaking most tube power amps can withstand a momentary short circuit. I'm not sure, but I suspect this only holds true for Output Transformer Coupled tube amps.
If you are saying that tube are less rugged mechanically, well then, I agree.