This one: https://phils-lab-shop.fedevel.education/
Also, you should check out those YT channels:
https://www.youtube.com/@AltiumAcademy
https://www.youtube.com/@RobertFeranec
https://www.youtube.com/@PhilsLab
Thanks, I'll take a look
Hi Bernhard,
I'm not going to get into a discussion about what some folks say we can sense or not. Current evidence clearly rules hypersonic sensing out. My own experience and observations bear this out as well. Believe me, I have been extremely open minded about this.
I'm actually getting very tired of arguments suggesting our human bodies can sense things we clearly do not have sensory organs to detect, and those we have are limited both by noise floor and frequency limits. Thinking about this, it makes perfect sense. We were evolved to survive and extraneous noise is detrimental to survival. Bats would drive us nuts, as would insects. So we evolved to filter that stuff out. Same for our internal body functions. Our sensors are all bandpass limited for good reason.
Humans are excellent survivors through evolution. Nature wastes nothing. We do not have super sensory abilities - period. A romantic notion to get around the notion of test instruments. Or, "we can play too - and better than folks who measure things". The trick is, we measure and listen - carefully. If an amplifier does not output extraneous signals, they do not exist. No magic involved.
I'm not going to get into a discussion about what some folks say we can sense or not. Current evidence clearly rules hypersonic sensing out. My own experience and observations bear this out as well. Believe me, I have been extremely open minded about this.
I'm actually getting very tired of arguments suggesting our human bodies can sense things we clearly do not have sensory organs to detect, and those we have are limited both by noise floor and frequency limits. Thinking about this, it makes perfect sense. We were evolved to survive and extraneous noise is detrimental to survival. Bats would drive us nuts, as would insects. So we evolved to filter that stuff out. Same for our internal body functions. Our sensors are all bandpass limited for good reason.
Humans are excellent survivors through evolution. Nature wastes nothing. We do not have super sensory abilities - period. A romantic notion to get around the notion of test instruments. Or, "we can play too - and better than folks who measure things". The trick is, we measure and listen - carefully. If an amplifier does not output extraneous signals, they do not exist. No magic involved.
I don't know about -20dB, and frankly I think it would have to be a repetitive sound in order to be picked up. If we are talking about enjoying music, often times the media itself may further raise the noise floor (records for example), and certainly enviromental sounds. I had at least one customer that would turn off all HVAC and refrigerators and anything else that made noise.while listening to music. He ran into system noise as an issue.
To be honest, enthusiast's have to come to terms about physical realities. There will be system noise. They may possibly be a hum component, or buzz maybe. In a system properly put ogether with good audio components, this noise floor will normally be below the level of enviromental noise. In other words, not normally a problem for a reasonable person. Often I measure 120 Hz components below -100 dB below 1 watt. Inaudible in other words in a real setting. Audio amplifiers delivering this performance have modest values of filter capacitance. Higher levels of capacitance do not seem to affect the levels of hum and 120 Hz components. It turns out to be more dependent on internal wiring and lead dress, ground layout and overall PCB layout.
I find the entire argument for extremely high amounts of filter capacitance an isolated examination that ignores the real world. In fact, the negative aspects of very high filter capacitance alone outweigh any possible benefits. If we are talking about overall performance, or engineering, we have to recognise that we are balancing off various aspects to achieve the best overall perfomance and reliability. I won't add in cost as it would be in a commercial venture. There simply is no valid case for a capacitance larger than a certain value depending on design and power level. I feel that arguments for high capacitance ignore the entire picture. When I was young I accepted the high capacitance idea to some degree, but as I actually measured performance and experienced amplfiers over many years, reality crept in and I had to then accept an engineering view.
More is seldom better. That view unbalances overall considerations as you optimize one factor at the expense of others. I really wish that engineering was as easy as "the highest amount of capacitance you can use". If this was true, where does it end, and how do you make the call? I have seen amplifiers with a separate chassis full of nothing but capacitors and a rectifier. They were not stellar performers for hum and 120 Hz output in case you were wondering.
To be honest, enthusiast's have to come to terms about physical realities. There will be system noise. They may possibly be a hum component, or buzz maybe. In a system properly put ogether with good audio components, this noise floor will normally be below the level of enviromental noise. In other words, not normally a problem for a reasonable person. Often I measure 120 Hz components below -100 dB below 1 watt. Inaudible in other words in a real setting. Audio amplifiers delivering this performance have modest values of filter capacitance. Higher levels of capacitance do not seem to affect the levels of hum and 120 Hz components. It turns out to be more dependent on internal wiring and lead dress, ground layout and overall PCB layout.
I find the entire argument for extremely high amounts of filter capacitance an isolated examination that ignores the real world. In fact, the negative aspects of very high filter capacitance alone outweigh any possible benefits. If we are talking about overall performance, or engineering, we have to recognise that we are balancing off various aspects to achieve the best overall perfomance and reliability. I won't add in cost as it would be in a commercial venture. There simply is no valid case for a capacitance larger than a certain value depending on design and power level. I feel that arguments for high capacitance ignore the entire picture. When I was young I accepted the high capacitance idea to some degree, but as I actually measured performance and experienced amplfiers over many years, reality crept in and I had to then accept an engineering view.
More is seldom better. That view unbalances overall considerations as you optimize one factor at the expense of others. I really wish that engineering was as easy as "the highest amount of capacitance you can use". If this was true, where does it end, and how do you make the call? I have seen amplifiers with a separate chassis full of nothing but capacitors and a rectifier. They were not stellar performers for hum and 120 Hz output in case you were wondering.
I agree with Chris many hobbyist go overboard on ecap sizing, there is a point where more don't make much difference other than to your wallet.
Folks go more for looks than function. What can I say some like big cans
In the book, chapter 4, the BC-1 PS uses a CRC design. It worked out rather well. My first attempt at wiring it all up, I was quiet surprised it was dead silent. I did not even bother or need to shorten the rather long transformer wires. I used a 10mF, 0.22R, 12mF setup. I winged it since I was unsure if I should put the 12mF before or after the 10mF. The 10mF are by far the cheapest for the build. Its debatable if separate supplies for each channel are of any advantage. Helps if the design has good PSRR.
I am having a hard time measuring the noise on the BC-1 reference amp. My Amber 3501 shows nothing on lowest scale 1mV.
So I built Mr. Groner's LNA in LA vol3 to use for testing. Its was a fun refresher in my smt soldering skills. I've been doing smt since the 80's its the first time I have assembled using MELF 0204. Just so happens I had enough BF862,235 to use for one build. If am bored I could build another one using the available 2SK3557-6-TB-E and compare. The fab files he posted are fine once you sort out whats what. Need a gerber viewer to figure that out. I have a zip file for jclpcb upload if anyone wants it. I also figured out all the necessary subs to use since many parts were either EOL or out of stock. There is a Mouser project for buying parts. I need to package it up to complete the build.
Measurements aside, your ears are pretty good noise meters held closely to an efficient speaker
I am using what's left of my ole rust bucket Ford 4x4, a 6x9 speaker, it works great for me
If I don't hear a damn thing it basically passes the test or I am going deaf . Next test headphones, I guess, wired directly to the speaker jacks, more cheap test speakers Would a hearing aid help
Folks go more for looks than function. What can I say some like big cans
In the book, chapter 4, the BC-1 PS uses a CRC design. It worked out rather well. My first attempt at wiring it all up, I was quiet surprised it was dead silent. I did not even bother or need to shorten the rather long transformer wires. I used a 10mF, 0.22R, 12mF setup. I winged it since I was unsure if I should put the 12mF before or after the 10mF. The 10mF are by far the cheapest for the build. Its debatable if separate supplies for each channel are of any advantage. Helps if the design has good PSRR.
I am having a hard time measuring the noise on the BC-1 reference amp. My Amber 3501 shows nothing on lowest scale 1mV.
So I built Mr. Groner's LNA in LA vol3 to use for testing. Its was a fun refresher in my smt soldering skills. I've been doing smt since the 80's its the first time I have assembled using MELF 0204. Just so happens I had enough BF862,235 to use for one build. If am bored I could build another one using the available 2SK3557-6-TB-E and compare. The fab files he posted are fine once you sort out whats what. Need a gerber viewer to figure that out. I have a zip file for jclpcb upload if anyone wants it. I also figured out all the necessary subs to use since many parts were either EOL or out of stock. There is a Mouser project for buying parts. I need to package it up to complete the build.
Measurements aside, your ears are pretty good noise meters held closely to an efficient speaker
I am using what's left of my ole rust bucket Ford 4x4, a 6x9 speaker, it works great for me
If I don't hear a damn thing it basically passes the test or I am going deaf . Next test headphones, I guess, wired directly to the speaker jacks, more cheap test speakers
Would a hearing aid help
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The magic is that by measuring THD with sinusoidal signals, we can measure what the amplifier has added, but we cannot measure what it has lost.
Then we wonder why an amplifier without negative feedback added more low-order harmonics and a total THD = 0.1%, but sounds much better than an amplifier with THD = 0.01%, and on a speaker system with THD> 1%. It would seem that they should sound the same.
Much more important is the lost information! And to measure it, completely different testing methods are needed.
I'm listening (pun intended). Which objective tests (instrument based) beyond freq.response & THD would reveal the lost information?
Not really. An instrument is a mechanical device which is subjected to the usual physical laws. That means, no infinite acceleration of matter, thus no infinite fast transient, thus no infinite spectrum.
Those transients build up amplitude relatively leisurely.
That means if you test or simulate an amp with infinitely fast signals, like a sinewave that starts from zero to something in zero time, you are using a signal that does not exist in real world audio.
Jan
Hi petr_2009,
I'm sorry, but you can't even seem to use logic chasing your views.
"Information lost" is distortion and will be measured by current tests quite easily. Any deviation from the original signal is easily measured and quantified.
I'm going to politely suggest you bow out to avoid embarrassing yourself any further. This is not going well for you.
-Chris
I'm sorry, but you can't even seem to use logic chasing your views.
"Information lost" is distortion and will be measured by current tests quite easily. Any deviation from the original signal is easily measured and quantified.
I'm going to politely suggest you bow out to avoid embarrassing yourself any further. This is not going well for you.
-Chris
Translation of ...may produce a infinite spectrum... : To a certain degree...
I thought that was clear in the context of my post.
The point was that even if it would exist, it could never pass the audio chain to challenge the amp in any way.
lol!
This could get amusing.
Anyway, signals with infinite spectrum can't possibly even make it to whatever media you play, and if you want to argue live sound, it would never get past the mic element and input RF filters in the mic amp. In any event, we can't even perceive signals like that, nothing in our human body will. Each of our senses have a defined spectrum they respond to. Thank goodness I can't hear light!
So why not limit our discussions to signals that are likely to pass through the audio chain for starters?
-Chris
This could get amusing.
Anyway, signals with infinite spectrum can't possibly even make it to whatever media you play, and if you want to argue live sound, it would never get past the mic element and input RF filters in the mic amp. In any event, we can't even perceive signals like that, nothing in our human body will. Each of our senses have a defined spectrum they respond to. Thank goodness I can't hear light!
So why not limit our discussions to signals that are likely to pass through the audio chain for starters?
-Chris
OK, you asked for it. Bob's book 1st Ed. pg 369 fig 17.4 shows his Klever Klipper, a soft clipper add on to an amp.
Pg 370 fig 17.5 shows THD-1kHz as a function of output power with and without the KK.
What bothered me was that with the KK, the THD starts to rise already at about half power.
So I did some sims and tests to vary the clip level and look at what point the THD starts to rise. It turns out that when you set the clip level higher, the THD starts to rise later. Of course that also means that signal levels are higher at clipping, so this needs to be taken account of in the amp design.
The attached has clip levels set at 1, 2, 3, 5 and 7 volts peak. You will see that with higher clip levels, the THD stays low longer; at 1V it already starts to rise at 0.75V; set at 7V, the rise starts at, well, 7V.
Comments?
Jan
Pg 370 fig 17.5 shows THD-1kHz as a function of output power with and without the KK.
What bothered me was that with the KK, the THD starts to rise already at about half power.
So I did some sims and tests to vary the clip level and look at what point the THD starts to rise. It turns out that when you set the clip level higher, the THD starts to rise later. Of course that also means that signal levels are higher at clipping, so this needs to be taken account of in the amp design.
The attached has clip levels set at 1, 2, 3, 5 and 7 volts peak. You will see that with higher clip levels, the THD stays low longer; at 1V it already starts to rise at 0.75V; set at 7V, the rise starts at, well, 7V.
Comments?
Jan
LOL
By the way, the term infinitely is often used literally, like the central banks are printing money infinitely, would you jump in and argue that this is not possible ?
If you want nitpicking:
You can not produce that signal in the real world either, because DACs & output stages have limited risetimes and electrons have a mass, so how would you like to test an amp with infinitely fast signals if you do not have them ?
There, fixed it for you.