Gentlemen (and any ladies present) please continue here:
I see several problems in this discussion.
First off we don’t seem to be talking the same language or terms.
I’ll define a hypothetical scenario and hope we can go from there. Or just take off as you were but please keep it in this thread.
I design three amps. I’m a competent engineer or DIY hobbyist who understands tube theory and can read the tube specifications so I do a good job. I use the same tube in all three amps, and my output transformers are wonderful.
1. SE 6L6GB 6.25W at 10%thd
2. PP 6L6GB class a 12.5W at 2%thd
3. PP 6L6GB class AB1 25W at 2%thd
They are driving nearly identical speakers in that the frequency response, distortion, etc are identical, only the efficiency varies (by 3dB/WM) such that all three produce the same acoustic pressure levels with the same input signal.
Which has the lower distortion?
Which sounds better?
Why?
Personal ramble starts here so jump to the next post as you wish.
In the early 70s as I remember it, bigger was always better. Bigger engines, bigger amplifiers, bigger speakers, bigger everything. Then the gas shortage in 74 pushed people to start thinking (at least temporarily) about efficiency and power consumption.
Push pull amps were bigger (higher power output) and therefore they were better. They used less power for the same output as a SE amp (of which there were very few commercial versions) so from an efficiency standpoint they were better.
Distortion was reduced to a meaningless number by GNFB.
Stereo sales persons were told to crank up the volume to impress the customer, and mess with their hearing. (My room mate at Clemson University worked for one of the local up scale audio stores and had a lot of interesting stories to tell.)
Bose 901s are great because they take lots of power
(no wrech imacon).
The fact is that PP amps naturally produce more odd harmonic distortion than SE amps. While the total THD (without GNFB) may or may not be less than a SE amp, the undesirable distortion is worse.
I believe the real reason big tube PP amps ruled the late 60s and early 70s was that most speaker efficiency was not that great. To get the loud levels that rock and later disco (remember that fad?) promoted, one needed lots of power.
Transistor amps were not necessarily better as much as they allowed music to be played louder. It was all driven by marketing and floor sales people.
Out of probably 30 friends at Clemson, I only know of one who had what would be today good speakers. That was my room mate Phil. He convinced me to get my first set of Heresy speakers and taught me a lot (what little I know) about stereo and sound reproduction.
I think I had the smallest amp of any of my friends (Sony STR5800SD 56wpc). But I had the most efficient speakers so I didn't care. I seriously doubt that any of them still have any of their stereo equipment. I still have both the Heresys and the Sony. Although the only reason I use the Sony now days is for it's phono input to play records into my computer to digitize them.
I see several problems in this discussion.
First off we don’t seem to be talking the same language or terms.
I’ll define a hypothetical scenario and hope we can go from there. Or just take off as you were but please keep it in this thread.
I design three amps. I’m a competent engineer or DIY hobbyist who understands tube theory and can read the tube specifications so I do a good job. I use the same tube in all three amps, and my output transformers are wonderful.
1. SE 6L6GB 6.25W at 10%thd
2. PP 6L6GB class a 12.5W at 2%thd
3. PP 6L6GB class AB1 25W at 2%thd
They are driving nearly identical speakers in that the frequency response, distortion, etc are identical, only the efficiency varies (by 3dB/WM) such that all three produce the same acoustic pressure levels with the same input signal.
Which has the lower distortion?
Which sounds better?
Why?
Personal ramble starts here so jump to the next post as you wish.
In the early 70s as I remember it, bigger was always better. Bigger engines, bigger amplifiers, bigger speakers, bigger everything. Then the gas shortage in 74 pushed people to start thinking (at least temporarily) about efficiency and power consumption.
Push pull amps were bigger (higher power output) and therefore they were better. They used less power for the same output as a SE amp (of which there were very few commercial versions) so from an efficiency standpoint they were better.
Distortion was reduced to a meaningless number by GNFB.
Stereo sales persons were told to crank up the volume to impress the customer, and mess with their hearing. (My room mate at Clemson University worked for one of the local up scale audio stores and had a lot of interesting stories to tell.)
Bose 901s are great because they take lots of power
(no wrech imacon).The fact is that PP amps naturally produce more odd harmonic distortion than SE amps. While the total THD (without GNFB) may or may not be less than a SE amp, the undesirable distortion is worse.
I believe the real reason big tube PP amps ruled the late 60s and early 70s was that most speaker efficiency was not that great. To get the loud levels that rock and later disco (remember that fad?) promoted, one needed lots of power.
Transistor amps were not necessarily better as much as they allowed music to be played louder. It was all driven by marketing and floor sales people.
Out of probably 30 friends at Clemson, I only know of one who had what would be today good speakers. That was my room mate Phil. He convinced me to get my first set of Heresy speakers and taught me a lot (what little I know) about stereo and sound reproduction.
I think I had the smallest amp of any of my friends (Sony STR5800SD 56wpc). But I had the most efficient speakers so I didn't care. I seriously doubt that any of them still have any of their stereo equipment. I still have both the Heresys and the Sony. Although the only reason I use the Sony now days is for it's phono input to play records into my computer to digitize them.
