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In Reply to: RE: the BUF-03's have no gain... but its most definately 'active'! posted by Ralph on November 08, 2024 at 08:32:54
In 1991, we didn't have AI. We didn't even have smart phones.
Follow Ups:
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Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
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It says it's passive with a buffer stage. Buffer stages are active. I think everyone knows that.
I must have missed something in this thread.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Not everyone, apparently, meaning me. I read Greenberg's article back in 1995, and took the 'passive' part of his 'Aunt Corey's Homemade Buffered Passive Preamplifier' title at face value, assuming he simply meant the absence of gain in the circuit. I never gave it much thought beyond that. Mia culpa, although 'Aunt Corey's Homemade Active Passive Preamplifier' would have been even more confusing. In retrospect, perhaps calling it a buffered line stage would have been a better choice
As I recall, there was bickering in the letters section about whether it should be called a 'preamp', since there was no amplification, but if there was an 'active vs passive' argument because of the buffers, I must have forgotten it.
...but your "Buffered Volume Control" really does accurately sum it up!
It is a passive preamp followed by a buffer. There is nothing wrong with Corey Greenberg's article.
Edits: 11/09/24
-to quote the mages of the Firesign Theater.
If its a passive control its not a preamp.
Any preamp manufacturer could claim they make a passive control using your terminology.
Whether the buffer afterwards has gain or not isn't so important, as the active circuit is there either way. The real question is how much damage is done.
I think I like Tre's definitions better.
When the source being used outputs more signal voltage than it takes to drive the power amp to full power, then all "preamps" are just attenuators.
If it's just a pot or a TVC/AVC with no active circuit involved then it's passive. The unit in question is a passive attenuator with an active buffer stage following it.
I think the term "preamp" should be reserved for phono preamps. The rest (active or passive) are line stages. But that's just how I look at it.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
True. And when that's the case, in theory at least, getting all the 'unnecessary' gain components out of the circuit ahead of the power amp should [note the italics] improve the transparency of the sound, I would think. Nelson Pass, in his B1 article wrote:
"Think of it this way: If you are running your volume control down around 9 o'clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up."
If you've never read it, his First Watt B1 Buffer Preamp article is linked below. Note that Pass was calling it a 'preamp' back in 2008, and guys were arguing whether Greenberg's should have been called a preamp back in 1995.
Your 'line stage vs phono stage designation makes sense to me, Tre', but we're swimming against the tide.
.
Have Fun and Enjoy the Music
"Still Working the Problem"
Usually a preamp with no gain is considered as passive. But this one is special. It has active circuits inside.In 1991, Motorola rocked.
Edits: 11/08/24
A passive component is, simply, one that does not require an external power source in order to function. A transformer is a passive device even though it can provide a voltage gain (albeit cost of current).
w/o any circuit, you call it active or passive.Please do not fussy about words. It is meaningless.
Edits: 11/08/24
Let's take the example of what happens if the power supply is disconnected.
If a motorized pot it will still play. An actual active circuit such as the one that is the subject of this thread will not.
Kapish?
Words have a lot of meaning. You can build everything on words including bankrupt.
The whole point of this thread is BUF03 not the passive.
There are many companies went to bankrupt because they voted the wrong CEO.
Our preamp has a passive volume control, but has active circuitry after it.
So its considered 'active'.
Just because a regular volume control (which in itself is passive) does not mean the circuit is considered passive if active devices are involved! Kal is correct.
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BUF03 perhaps is the only opamp in class A mode on this earth.
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Do you remember the model number of the class A opamps you mentioned? I am very interested. Thanks a lot!
-just one, common, example.
It is good to know that NE5534 is a class A opamp. Wow!!!Which planet are you on?
Edits: 11/11/24
see link.
Good point so you can use any cheap opamp in your products.
Things like gain bandwidth product affect it more. Nice to have low noise too.
Very true. When all the people on this planet get used to the sound of class D. They do not miss class A a single bit.
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There are two kind of liars. Blink eyes/ do not blink eyes
I didn't miss Class A way before I started auditioning Class D amps. The Class A amps I had seemed rather smooth, polite, and dynamically challenged. I owned better sounding Class AB amps. To be perfectly honest I don't think it's a "Class" thing. There are good and bad sounding amps in all Classes.
I've had several different Class D amps in and out of my system over the past 25 years. Class D has improved incrementally over time and I find that there are a number of outstanding current generation Class D amps. I've been running a couple with excellent results for the past 5 years.
Wow, an old friend.
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The NE5534 is a low-noise, single operational amplifier (op amp) that is not specific to a particular class of amplifier. However, class AB amplifiers are a combination of class A and class B amplifiers that can be more efficient than class A while having less distortion than class B.
From what I've seen most opamps operating in Class A or one leg of the output biased Class A (single ended), can't dissipate much power. I suppose one can add a transistor buffer at the output - a FET or even an old school bipolar darlington configuration.
Edits: 11/09/24
and output impedance down to 2ohms. Is that enough?
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