EUVL, you ask an interesting question. IF I could do it over again, I might choose 20 or even 10 ohms instead of 47. I originally designed this preamp for 5K+ loads, so 47 ohms is OK, but Stereophile tested it with a 600 ohm load at one point. 20 ohm resistors would have allowed more idle current and somewhat better performance, but I was unsure of the heatsinks I would get, 10+ years ago, so I opted to lower the idle current to 20ma or so. Actually 50-100 ma would have been slightly better, but a lot hotter.
You know guys, REAL ANSWERS are tough to formulate, and even understand. Most engineers and many non-PhD physicists, like myself are kept from the REAL knowledge as a matter of course, or 'need to know'. I don't even have to really understand how a transistor works in order to use it properly. An so it goes!
Ed
I just wouldn’t like to see a series of posts that turns into an unproductive waste of energy.
To quote you
"Emotionality does not belong here, it is better expressed while listening to music".
On the other hand I fully understand that fundamental concepts are the hardest to understand and the most difficult to explain.
George
P.S. Jacco, which amp (brand, model) was this ?
Attachments
George
It has been an interesting week.
Now my late maternal grandmother and her lineage have a way to draw out what could otherwise be a succinct story. So I call this process in their family name honor to "Busis" a story. (Pronounced Byu-Cis not Bus-is.)
The best example of this is one night at a family dinner, just as my father took his first bite of the main course my grandmother looked at him and said "You don't have to worry about the fire."
Not surprisingly he began to gag on his first mouth full. So my grandmother added "I told you, you don't have to worry."
It has been an interesting week.
Now my late maternal grandmother and her lineage have a way to draw out what could otherwise be a succinct story. So I call this process in their family name honor to "Busis" a story. (Pronounced Byu-Cis not Bus-is.)
The best example of this is one night at a family dinner, just as my father took his first bite of the main course my grandmother looked at him and said "You don't have to worry about the fire."
Not surprisingly he began to gag on his first mouth full. So my grandmother added "I told you, you don't have to worry."
Last edited:
To continue, today about the only slightly unusual thing was on my way home as I was driving home on old route 28 I passed a bicyclist wearing no helmet, a black coat riding a red what we used to call an English racer, just about to enter the road construction zone.
The road work has narrowed a four line road to two and because this congestion causes poor merging, drivers fixated on preventing that proceeding well and all the rest I did not stop to yell at him.
The road work has narrowed a four line road to two and because this congestion causes poor merging, drivers fixated on preventing that proceeding well and all the rest I did not stop to yell at him.
Last edited:
Now yesterday just before leaving work I looked out the door to see my parking lot obscured by very thick smoke.
Now my parking lot used to be a small stream. When the new route 28 was built they filled in the stream. It quickly became a dump because the building I now own used the other end of the building for the front door.
When I bought the property a survey done for the previous owners showed that filled in stream belonged to someone else. Now as a great uncle on my father's side was a surveyor of note (laid out half of the path from LA to the dam at Boulder, Grand Canyon National Park, Israel etc.) who came to live with us for a bit after he retired. He would always ask we kids questions and provide the answers. A good number of these were about surveying.
So when I saw the plot the errors popped out. With the internet the research was easy to do.
Now the town my building is in is called Sharpsburg, named after the fellow who started it in 1846. Town legend has it he was helped to settle by Seneca Indian Chief Guyasuta. So there is a statue of the chief, a Boy Scout camp and a road named in his honor.
Of course a bit of looking showed Chief Guyasuta had died in 1798.
Seems the chief had been a scout for the British and during colonial times worked with George Washington. When the revolution came the chief and the Seneca Nation sided with the British. After the war a treaty was signed and they moved north to Canada. Today they run a casino on their sovereign territory in NY state.
Well the department of war gave their land to a former revolutionary war quartermaster probably instead of the money they owed him. The reason why he was such an important figure is that as a colony manufacturing was prohibited. But as this area was so deep in the woods and far away from civilization, illegal irons works had set up shop. So the bright fellow associated with the criminals and was able to secure muskets, rifles and cannon!
Well it was a bit of his estate that was sold to Mr. Sharp. His family kept some and the dividing line was the stream that became my parking lot due to one of those laws that should be known to surveyors.
That is that when a right of way is abandoned the owners of the adjoining property split it. In my case the other side was a railroad that had a right of way not ownership. So technically the parking lot is mine but it is only half in Sharpsburg and the other half in the next town named Etna.
So when the truck from the matress store down the road started smoking the driver pulled into the lot.
Now my parking lot used to be a small stream. When the new route 28 was built they filled in the stream. It quickly became a dump because the building I now own used the other end of the building for the front door.
When I bought the property a survey done for the previous owners showed that filled in stream belonged to someone else. Now as a great uncle on my father's side was a surveyor of note (laid out half of the path from LA to the dam at Boulder, Grand Canyon National Park, Israel etc.) who came to live with us for a bit after he retired. He would always ask we kids questions and provide the answers. A good number of these were about surveying.
So when I saw the plot the errors popped out. With the internet the research was easy to do.
Now the town my building is in is called Sharpsburg, named after the fellow who started it in 1846. Town legend has it he was helped to settle by Seneca Indian Chief Guyasuta. So there is a statue of the chief, a Boy Scout camp and a road named in his honor.
Of course a bit of looking showed Chief Guyasuta had died in 1798.
Seems the chief had been a scout for the British and during colonial times worked with George Washington. When the revolution came the chief and the Seneca Nation sided with the British. After the war a treaty was signed and they moved north to Canada. Today they run a casino on their sovereign territory in NY state.
Well the department of war gave their land to a former revolutionary war quartermaster probably instead of the money they owed him. The reason why he was such an important figure is that as a colony manufacturing was prohibited. But as this area was so deep in the woods and far away from civilization, illegal irons works had set up shop. So the bright fellow associated with the criminals and was able to secure muskets, rifles and cannon!
Well it was a bit of his estate that was sold to Mr. Sharp. His family kept some and the dividing line was the stream that became my parking lot due to one of those laws that should be known to surveyors.
That is that when a right of way is abandoned the owners of the adjoining property split it. In my case the other side was a railroad that had a right of way not ownership. So technically the parking lot is mine but it is only half in Sharpsburg and the other half in the next town named Etna.
So when the truck from the matress store down the road started smoking the driver pulled into the lot.
When I called the emergency telephone number 9-1-1 (The second time in two days) the county emergency center asked where I was located so they could notify the correct department.
Now as both Sharpsburg and Etna have volunteer fire departments, I asked for the local police department, as they know the lot well as it is one of their rally places.
I mentioned the smoke and that the driver exited the truck and thought it might bare further clarification.
The officer showed up, left and a few minutes later both fire departments showed up along with two police vehicles.
Now at this time the truck driver's assistant decided it was time to get out of the burning truck. (Insert your own comment on the intelligence of the assistant.)
Now for those familiar with the WWII PT boats they used to spray diesel fuel on their engines exhaust manifolds to make smoke. So I was aware a bit as to how much smoke diesel fuel could make without an actual fire.
That was the case here, so as the non-fire was not as exciting as the day before I went home with the full crowd still in my parking lot.
Now after my father finished choking my grandmother's story finally came out. A building they jointly owned had a dry bearing in the HVAC blower and someone saw the smoke and called the fire department. So as there was no fire there was nothing to worry about.
Which brings up the more interesting part of the story. Why I called 9-1-1 the first time this week.
Now as both Sharpsburg and Etna have volunteer fire departments, I asked for the local police department, as they know the lot well as it is one of their rally places.
I mentioned the smoke and that the driver exited the truck and thought it might bare further clarification.
The officer showed up, left and a few minutes later both fire departments showed up along with two police vehicles.
Now at this time the truck driver's assistant decided it was time to get out of the burning truck. (Insert your own comment on the intelligence of the assistant.)
Now for those familiar with the WWII PT boats they used to spray diesel fuel on their engines exhaust manifolds to make smoke. So I was aware a bit as to how much smoke diesel fuel could make without an actual fire.
That was the case here, so as the non-fire was not as exciting as the day before I went home with the full crowd still in my parking lot.
Now after my father finished choking my grandmother's story finally came out. A building they jointly owned had a dry bearing in the HVAC blower and someone saw the smoke and called the fire department. So as there was no fire there was nothing to worry about.
Which brings up the more interesting part of the story. Why I called 9-1-1 the first time this week.
Last edited:
Tuesday morning I got up early to drive to Buffalo. It was just about sunrise as I lined up on the bridge to turn right onto old route 28 north. Three cars ahead if me turned right and then two left.
So as the four of us headed north with my car in the rear by about 300' I noticed the first car passed a black object that began to wobble. It fell over as the second car passed it. The third car moved over to avoid the object which cleared my view of it. Looked like a bit of tree had been downed in the previous nights storm.
So I moved over to avoid it also. When I got about 25' away the low morning light from the east reflected off the spikes of the bicycle's tire.
So as the four of us headed north with my car in the rear by about 300' I noticed the first car passed a black object that began to wobble. It fell over as the second car passed it. The third car moved over to avoid the object which cleared my view of it. Looked like a bit of tree had been downed in the previous nights storm.
So I moved over to avoid it also. When I got about 25' away the low morning light from the east reflected off the spikes of the bicycle's tire.
Heraclitus would remind us that you can never step in the same parking lot twice.
I've been wondering why the concept of weighted THD has never caught on. I read about the audibility of different harmonics in a white paper by…John Curl. I believe it's easily verified that human hearing is far more sensitive to certain harmonics than others. So given that we now have software-based analysis that easily determine the levels of different harmonics and weight them, why aren't people doing this? Then we could have a measurement that is more applicable to auditory perception than just THD.
because there's better research, metrics with greater predictive power?
GedLee Metric, some work using the psychoacoustics, controlled human listening testing that went into lossy codec development
because competent electronics, transducers really only have lower order nonlinearities - anything producing measurable 17th harmonic is grossly clipping or snapping across a dead-band
because negative feedback around circuits that don't have open loop dead bands, aren't clipping/limiting in some way actually works
GedLee Metric, some work using the psychoacoustics, controlled human listening testing that went into lossy codec development
because competent electronics, transducers really only have lower order nonlinearities - anything producing measurable 17th harmonic is grossly clipping or snapping across a dead-band
because negative feedback around circuits that don't have open loop dead bands, aren't clipping/limiting in some way actually works
Last edited:
There's the work of Earl Geddes, among others. The concept is too subtle to be understood by most marketing types, I'm afraid. But it is not unknown.
And IM distortion, although closely related, is more important to most.
edit: late notification of jcx post
Last edited:
- Status
- Not open for further replies.