I know that the claimed magic of SET has not revealed itself in my system when played over an extended listening period at a range of levels. I know that the SET I built and listened to sounded very similar to the PP amps I built and listened to. There are particular reasons why that might be - specifically related to my choice of OT (parafeed) which allows me to have an informed opinion on the impact of OT's on sound.
That is my personal experience which is all I can give - what is your personal experience of comparing like for like SET to PP - because that obviously all you can give and you haven't done so yet,
Shoog
Depends on the design. It would be worthwhile for you to read about the design for one type here: The Amity, Raven, and Aurora
Essentially, as has been noted earlier, the input and driver stages are relatively speaking perfect when compared to the output stage. This was verified by measurement. The capacitor from plate to cathode helps alleviate the need for close tube matching. So when pushed hard, the PP does start to distort on the output stage (doesn't every amp?). However, this distortion does not really get significant until you run into the 10W range or so. I don't run my amps anywhere near this hard, nor would I say most SE people do (if they can even get 10W). Transients are not a critical discussion point, IMO, because the transients that would require 10W would normally be in the bass region, where the audibility of distortion becomes almost irrelevant (most bass drivers have 10 to 100 times more distortion than the average amp). Besides, my PP runs 100Hz and up, so I don't worry about requiring 10W.
Essentially, as has been noted earlier, the input and driver stages are relatively speaking perfect when compared to the output stage. This was verified by measurement. The capacitor from plate to cathode helps alleviate the need for close tube matching. So when pushed hard, the PP does start to distort on the output stage (doesn't every amp?). However, this distortion does not really get significant until you run into the 10W range or so. I don't run my amps anywhere near this hard, nor would I say most SE people do (if they can even get 10W). Transients are not a critical discussion point, IMO, because the transients that would require 10W would normally be in the bass region, where the audibility of distortion becomes almost irrelevant (most bass drivers have 10 to 100 times more distortion than the average amp). Besides, my PP runs 100Hz and up, so I don't worry about requiring 10W.
'Depends on the design' you say...
This is an example of what makes me shake my head in disbelief. Who, when, how - came to irreversible conclusion that the above designs are the summit of what's possible with tube PP? I'd like to know that. I'd like to see - in this thread - those 'in the know' show, without any trace of doubt left - by comparing all existing tube PP topologies and different tubes used - that it is so. And then, only then, can be 'the PP champion' put against 'the SE champion' to claim the crown of blissful aural presentation. But. Hold. On. The SE crowd themselves cannot agree... Which design? Which tubes?
'Depends on the design'...
My 5 cents: not having 'the champion design' is a blessing, not a curse... I don't get it when people are trying to prove/convert/live and not let others die...
Last edited:
No one claims that these specific designs are the ultimate, but by measured and subjective performance they rate very highly among all who have listened to them. The dpt300B has won many best product awards over a number of years. Lyn Olsens designs are not commerically available so it is the few who have DIYed them who have worthwhile things to say.
Its worth at the very least building one based on the same design principles and comparing them to the best you already have. There is absolutely nothing to lose other than the conviction that your own chosen topology is better. What annoys me is when people refuse to countenance that they might be in something of a ghetto of their own making. I tested the claim's made for SE and found them overstated, thats an informed opinion based on building a very pure high performance SE and comparing it to amps based on Allan Wrights, Lyn Olsen and Gary Pimms approach to building high spec PP amps. If you don't like that opinion please ignore it - but don't claim you know better if you haven't made similar comparisons yourself.
Let me remind people that the only reason this whole side track started was because an SE advocate stated that crossover distortion was inherent within PP designs. I corrected them for their misunderstanding. A number of other PP myths have also been stated here. This sort of misapprehension prevents people from taking PP seriously and it needs to be corrected whenever they are falsely claimed.
Shoog
Its worth at the very least building one based on the same design principles and comparing them to the best you already have. There is absolutely nothing to lose other than the conviction that your own chosen topology is better. What annoys me is when people refuse to countenance that they might be in something of a ghetto of their own making. I tested the claim's made for SE and found them overstated, thats an informed opinion based on building a very pure high performance SE and comparing it to amps based on Allan Wrights, Lyn Olsen and Gary Pimms approach to building high spec PP amps. If you don't like that opinion please ignore it - but don't claim you know better if you haven't made similar comparisons yourself.
Let me remind people that the only reason this whole side track started was because an SE advocate stated that crossover distortion was inherent within PP designs. I corrected them for their misunderstanding. A number of other PP myths have also been stated here. This sort of misapprehension prevents people from taking PP seriously and it needs to be corrected whenever they are falsely claimed.
Shoog
Last edited:
Hiraga reported by someone else and quoted by dhsettim:
Those pursuing hi-fi get their distortion sufficiently low, then rely on masking to hide the little which remains. Those pursuing a nice sound just choose whichever distortion profile sounds nice to them.
This might be true if you could switch off the internal distortion. You can't, so it isn't true. Applying a distorted signal to a distorted channel just gives higher order distortion, unless the predistortion exactly matches the inverse of the distortion function. Note that finite order distortion requires infinite order pre-distortion, and infinite order distortion will almost always require infinite order pre-distortion too. The chances of getting an amplifier (SET or anything else) to exactly match the ear at different signal levels (yes, distortion always varies with signal level) is exactly zero.
Those pursuing hi-fi get their distortion sufficiently low, then rely on masking to hide the little which remains. Those pursuing a nice sound just choose whichever distortion profile sounds nice to them.
Same old:
ascetics (or should we say masochists)
vs
hedonists
or
should we trust our ears (in front of speakers)
vs
should we trust our eyes/mind (in front of analyzer screens or doing math)
Which one is more beneficial to our audio experience? Which one is more beneficial to *my* audio experience? I sure do know the answer, and I sure will not take my answer to be better/higher than anyone else's...
It doesn't have to be an either or. There are poor designs which mask their sound with copious amount of gNFB. There are poor designs which do nothing about the distortion.
Then there are the good designs
To me throwing a blanket of 2nd harmonic over the output seems as bad, or worse, than masking it with copious amounts of gNFB. I don't see how you can make it your objective to increase the overall distortion and think that it will sound better, but that just personal taste.Shoog
Last edited:
I know which is more beneficial to my audio experience. As to 'better' vs. 'higher' I did not comment on that, but I will now. 'Better' implies some form of value system or means of evaluation, which engineering certainly implies. 'Higher' may simply mean more expensive, or accompanied by a good story.fullrangeSR said:
Let's go back to post #1 and reask the question in a clearer way.
Example for 7189 (6BQ5 similar).
From the data sheet, typical SE operation at 250v gives 10% THD.
For PP class AB1 for 2 tubes also at 250v it says 3% THD.
What's in the SE THD that's not in the PP AB1 THD, or what's not in the PP THD?
Then, if the PP amp's power was pulled back into Class A only, by lowering the input signal, what would the THD fall to or would it rise to something similar to the SE since the tubes are now conducting for 100% of the cycle?
20
Example for 7189 (6BQ5 similar).
From the data sheet, typical SE operation at 250v gives 10% THD.
For PP class AB1 for 2 tubes also at 250v it says 3% THD.
What's in the SE THD that's not in the PP AB1 THD, or what's not in the PP THD?
Then, if the PP amp's power was pulled back into Class A only, by lowering the input signal, what would the THD fall to or would it rise to something similar to the SE since the tubes are now conducting for 100% of the cycle?
20
Quoting THD without mentioning power does not tell us very much. However, it is reasonable to suppose that the figures given are for near maximum power, a bit below clipping. This probably means the PP figure is for somewhere between 2 and 4 times the SE power. Let's be generous to SE and assume just 2. Let's be generous to PP and assume little or no crossover distortion. Then halving the PP power mean sqrt(2) less voltage so the 3% THD becomes about 2% or about 1.5% (depending on whether 2nd or 3rd dominates). So at the same power level PP will have at least 5 time less distortion than SE. The harmonic balance will be different, with SE having much more 2nd and other even-order terms.
Let's look at even smaller signals, more like normal listening levels, by halving the signal voltage. Then SE (mainly 2nd) will be 5% THD. PP will be somewhere between 1% (if 2nd dominates) to 0.4% (if 3rd dominates).
All very rough calculations, but they show that PP has significantly less distortion. People can't have it both ways: if they object to 2nd then they must prefer PP; if they object to 3rd then they simply have to run a PP at a similar power level to SE and get less 3rd and much less 2nd. SE only scores for people who prefer 2nd over no 2nd.
Let's look at even smaller signals, more like normal listening levels, by halving the signal voltage. Then SE (mainly 2nd) will be 5% THD. PP will be somewhere between 1% (if 2nd dominates) to 0.4% (if 3rd dominates).
All very rough calculations, but they show that PP has significantly less distortion. People can't have it both ways: if they object to 2nd then they must prefer PP; if they object to 3rd then they simply have to run a PP at a similar power level to SE and get less 3rd and much less 2nd. SE only scores for people who prefer 2nd over no 2nd.
We don't have to assume anything. The data sheet gives the power consumption, output, drive levels, currents... for the P voltage. The 7189-A data sheet gives very nice distortion graphs for both SE and PP.
The answer isn't even that relevant in this case since the design will be employing significant levels of local feedback around the output tube.
The main consideration has to be - does the input pentode have enough balls to not be the dominant source of distortion.
The answer can only be found by measurement or modeling.
Shoog
The main consideration has to be - does the input pentode have enough balls to not be the dominant source of distortion.
The answer can only be found by measurement or modeling.
Shoog
Last edited:
The answer to post #1 isn't "in front" of anyone from the data sheet.
I'm just getting the thread back on track.
The wild difference in THD was the basis for post #1.
20
Its interesting,
That the large SE amps like 211 and 845 etc that are thought by many to be the ultimate Audiophile nirvana are now tied to a post and burnt alive.
So the next question is whats missing from recorded material if people prefer tube amps? Or is it the recorded material contains harmonics from the studio that people don't like?
If an amp was just an amp (SS or tube) why do people keep going back to tube or looking for better SS or tube pre<<the excuse is it takes the harshness off the sound??? (Harshness)<<<
Regards
M. Gregg
That the large SE amps like 211 and 845 etc that are thought by many to be the ultimate Audiophile nirvana are now tied to a post and burnt alive.
So the next question is whats missing from recorded material if people prefer tube amps? Or is it the recorded material contains harmonics from the studio that people don't like?
If an amp was just an amp (SS or tube) why do people keep going back to tube or looking for better SS or tube pre<<the excuse is it takes the harshness off the sound??? (Harshness)<<<
Regards
M. Gregg
Last edited:
Its interesting,
That the large SE amps like 211 and 845 etc that are thought by many to be the ultimate Audiophile nirvana are now tied to a post and burnt alive.
So the next question is whats missing from recorded material if people prefer tube amps? Or is it the recorded material contains harmonics from the studio that people don't like?
Regards
M. Gregg
Very few people actually prefer and stick with SE amps long term. Most people bring them out for a bit of nostalgia and then plug their PP amps back in for real world use. This is a statistically provable fact.
Those who actually prefer SET are a tiny minority of a relatively tiny audio club.
Shoog
Its a pretty expensive small club if bought as a commercial amp..
I will agree that some people say they want a tube amp because of the (warm sound). That includes PP.
Regards
M. Gregg
Last edited:
Its a pretty expensive small club if bought as a commercial amp..
I will agree that some people say they want a tube amp because of the (warm sound).
Regards
M. Gregg
Which speaks to DF96's point more than anything else.
Shoog
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.