John Curl's Blowtorch preamplifier part III

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Yes, some of us scrounge a living from audio design. It is not usually a lucrative one, except for a few marketeers who luck out with a specific product. We designers are usually seriously underpaid, so why do we stick with it? Because we love what we are doing, and we hope to improve the audio experience. The rest of you who have your government or industry jobs, probably make a better salary, so I hope it keeps you satisfied. I found that I could not happily work, except for short periods, like 1 year or so in anything but audio, but that is just me. Of course I have tried several times, over the many decades of my work (more than 55 years) to work in industry, and I found it both interesting (up to a point) and informative (useful for audio too), but I can't even easily remember the exact schematics that I developed for servos, RF amps, control circuits, etc. It just did not matter that much, and I knew that I was just a person hired to help with the development of a product, such as a video recorder or a medical laser. It just did not sustain me, like a lower paying position in audio design.
Now, does this bias me in some way toward selling audio to unsuspecting customers? I don't think so. I could care less if anyone here would ever buy one of my audio designs, as my royalties are so far removed from any one person or persons, but I DO care about learning MORE as to what is WRONG with digital, so that I can be able to enjoy it further. That is what I get from this thread at the moment, and keep those LINKS coming!
 
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Look at the (audible?) GDelay approaching the cut-off freq.

However, their IS insufficient atten of the filter output. Significant HF energy level is being sent to the amp/speaker. NOT a good idea. It is only -70dBv down and if sent to a preamp/PA with some total gain X ... a lot of HF PA energy is going thru amp and tweeter.


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Conjecture --> It may be one reason a faster SR and lower distortion at HF of CFA or current-mode amp reduces some of the IM generated from the high levels of HF present.

Thx-RNMarsh


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Yep, i can and i could in the past........

Good, can you identify one for me? Not holding my breath for an answer :D.

As stated before it is a fairly trivial exercise to convert a CFA to H-bridge VFA with identical performance with respect to slew and distortion.

In the eyes of certain Believers, a H-bridge would still be a CFA (or a "Current Mode Amplifier", whatever that is). Arguing about is futile, you will be assimilated.
 
Good, can you identify one for me?

There are a couple that I know of, one posts in this thread at times depending on the topic under discussion. The other one hasn't posted in this thread for quite awhile. I believe Jakob identified one of them.

One or more that used to be here has or have found another forum dominated by like minded people and where non-conforming speech by non-believers is quickly suppressed.

Obviously, it works the other way too, I am told there are audio forums where anything goes except advocating for more reliance on measurements, physics, and college level engineering analysis.

No interest in either type of extreme myself. I certainly believe in established physics and engineering, but remain skeptical about a lot of old research into human perception where brain processing plays a very large role.
 
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There are a couple that I know of, one posts in this thread at times depending on the topic under discussion. The other one hasn't posted in this thread for quite awhile. I believe Jakob identified one of them.

You guys must have the extraordinary ability to read each other minds, I have no idea what/who are you talking about.

Myself, I suppose I don't spend enough time on this forum to be entitled to a qualified opinion regarding other members. Shame on me :D
 
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As stated before it is a fairly trivial exercise to convert a CFA to H-bridge VFA with identical performance with respect to slew and distortion.

Great but so what? Thats not the point. I am talking about how well some circuits handle HF better than others and there is good need for it to do so.
Those that do not... most ? ...will produce audible artifacts. The filters are not removing enough of the HF junk moved upward in freq from DAC output.

Any VFA with typical low OL BW and rising THD with freq above 20KHz is going to sound worse than a typical CFA. This HF presence is one of the reasons. Otherwise, both VFA and CFA would do about as well, audibly, without the HF presence. Most if not all CD player of recent vintage has significant HF on its output.



THx-RNMarsh
 
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You guys must have the extraordinary ability to read each other minds.

That is probably the least likely possibility, which no doubt you know. This place has a long history much of which is only related to me in incomplete bits and pieces, but the history of the two is not a secret, just not something currently talked about. In some ways maybe it is like the method I know of to 'peek' at foobar ABX. I have described it in the past so that a few people know that I know how, but there is no reason to keep describing it. Enough has been said, no need for more.
 
There are a couple that I know of, one posts in this thread at times depending on the topic under discussion. The other one hasn't posted in this thread for quite awhile. I believe Jakob identified one of them.
But something is keeping you from disclosing the forum names. Could it be because you aren't sure?
No interest in either type of extreme myself. I certainly believe in established physics and engineering, but remain skeptical about a lot of old research into human perception where brain processing plays a very large role.
The skepticism you are referring to would apply to sound played but not to replayed sound. You still can but you would be reinventing the wheel. IOW, it's been done already.

That is probably the least likely possibility, which no doubt you know. This place has a long history much of which is only related to me in incomplete bits and pieces, but the history of the two is not a secret, just not something currently talked about. In some ways maybe it is like the method I know of to 'peek' at foobar ABX. I have described it in the past so that a few people know that I know how, but there is no reason to keep describing it. Enough has been said, no need for more.
You've joined this forum in July of 2016 and you are saying something about long history of the forum to someone who joined in August of 2005? :scratch:
 
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