PMA, the best part of hi end is to do things the best way possible. Mid-fi is making things the easiest and cheapest way possible.
Also, I spoke today with Charles Hansen who is part of 'AudioXpress'. We discussed resistors and his account was virtually the same as mine. OF COURSE, the military and industrial firms used many more 1% resistors, even in the 1960's, which was my first 5 years of experience in the industry. After all, we could not have purchased 1% resistors made in the 1960's, IF they had not been produced for the military-industrial complex.
Also, I spoke today with Charles Hansen who is part of 'AudioXpress'. We discussed resistors and his account was virtually the same as mine. OF COURSE, the military and industrial firms used many more 1% resistors, even in the 1960's, which was my first 5 years of experience in the industry. After all, we could not have purchased 1% resistors made in the 1960's, IF they had not been produced for the military-industrial complex.
I guess the next thing we'll hear that the solder mask add "a certain air" to the sound?
I've been working 30 yrs+ in instrumentation and small scale prototyping, using all the "worst amateur technology" there is, and probably some more. Most of them works OK. If the question is about durability and reliability of circuit boards, that's something totally different. Production prices of small scale PCB series have dropped radically the last years, and are now accessible to everyone using PCB CAD systems. That does not mean there is anythting wrong with producing your own one offs or prototypes using "amateur technology", provided it's done properly with a certain minimum of equipment. As for for PCB durability, the selection of spray can chemicals is truly overwhelming.
As for the gold plating of boards, it most certainly looks impressive. If it helps the sound quality, I just can't tell. What is for certain, though, is that soldering on gold plated PCBs, it is actually not recommended, and is discouraged according to among other things, mil spec soldering procedures.
EDIT: OTOH - even I do know there is a lot of boards out there, with gold plated pads.....
I've been working 30 yrs+ in instrumentation and small scale prototyping, using all the "worst amateur technology" there is, and probably some more. Most of them works OK. If the question is about durability and reliability of circuit boards, that's something totally different. Production prices of small scale PCB series have dropped radically the last years, and are now accessible to everyone using PCB CAD systems. That does not mean there is anythting wrong with producing your own one offs or prototypes using "amateur technology", provided it's done properly with a certain minimum of equipment. As for for PCB durability, the selection of spray can chemicals is truly overwhelming.
As for the gold plating of boards, it most certainly looks impressive. If it helps the sound quality, I just can't tell. What is for certain, though, is that soldering on gold plated PCBs, it is actually not recommended, and is discouraged according to among other things, mil spec soldering procedures.
EDIT: OTOH - even I do know there is a lot of boards out there, with gold plated pads.....
Gold plating is one good way to reduce corrosion and remove the 'possibility' of DA problems.
This is how we did it:
The first Vendetta boards were FR-4 and solder plated traces.
The second Vendetta boards were gold plated.
The third Vendetta boards were made from something better than FR-4, but not as exotic as teflon, and gold plated
Today's Vendetta boards will be made of Teflon and coated with an 'ADVANCED' low DA coating, only on the non-soldered areas of the board. This is how we made CTC 'Blowtorch' boards and we are not going back.
We will clean each board and hand scrape every component, some of which are more than 20 years old, just before mounting and soldering.
Decades ago, I experimented with acrylic and better coatings, virtually everything from M S. I could not determine the DA contribution.
This is how we did it:
The first Vendetta boards were FR-4 and solder plated traces.
The second Vendetta boards were gold plated.
The third Vendetta boards were made from something better than FR-4, but not as exotic as teflon, and gold plated
Today's Vendetta boards will be made of Teflon and coated with an 'ADVANCED' low DA coating, only on the non-soldered areas of the board. This is how we made CTC 'Blowtorch' boards and we are not going back.
We will clean each board and hand scrape every component, some of which are more than 20 years old, just before mounting and soldering.
Decades ago, I experimented with acrylic and better coatings, virtually everything from M S. I could not determine the DA contribution.
Schweinerei.
Such reasoning makes a 250 dollar computer eligible for the title.
Production perfectionism may have been a standard up to 10, 15 years ago, but some have moved on.
By these standards, a number of truly hi end manufacturers would not be alive today.
For instance FMAcoustics, a brand i personally had great difficulty with for some time because of lacking stuff like soldermasks, doublesided boards and the attic hobbyroom general appearance of the insides.
Seems to me that is still what this thread is about: looks aren't everything, honey.
(Cramolin cleaner is readilly available overhere for about $8 the can)
Such reasoning makes a 250 dollar computer eligible for the title.
Production perfectionism may have been a standard up to 10, 15 years ago, but some have moved on.
By these standards, a number of truly hi end manufacturers would not be alive today.
For instance FMAcoustics, a brand i personally had great difficulty with for some time because of lacking stuff like soldermasks, doublesided boards and the attic hobbyroom general appearance of the insides.
Seems to me that is still what this thread is about: looks aren't everything, honey.
(Cramolin cleaner is readilly available overhere for about $8 the can)
Now WHY did I change my board construction? Remember, the original board LAYOUT is exactly the same in each rendition"
First, solder plate turns grey to black over time, just sitting around. It oxidizes. Is this OK?
Gold plating, 20+ years ago was pretty darn good! A 'thick' gold plating looks good, stays looking good, and can be easily cleaned.
However, gold is VERY touchy to solder splashes, and we always had cosmetic problems and shorts. Later, about 18 years ago, my last batch of boards did NOT have the same gold plating thickness, and the copper would spot through. It looked like a case of measles, even when the boards were stored.
Still, I resisted, because of potential DA problems. Finally, when we started the CTC boards , about 10 years ago, Carl Thompson convinced me that a NEW group of conformal coatings were made for high speed computers, with low DA. We used it with the CTC line amp and we still got good results. It was MUCH easier to solder the board, as well. We also improved the substrate from FR-4 to 'Nylon' to Teflon. No use inviting
circuit hook' described by Tektronix 33 years ago or so.
First, solder plate turns grey to black over time, just sitting around. It oxidizes. Is this OK?
Gold plating, 20+ years ago was pretty darn good! A 'thick' gold plating looks good, stays looking good, and can be easily cleaned.
However, gold is VERY touchy to solder splashes, and we always had cosmetic problems and shorts. Later, about 18 years ago, my last batch of boards did NOT have the same gold plating thickness, and the copper would spot through. It looked like a case of measles, even when the boards were stored.
Still, I resisted, because of potential DA problems. Finally, when we started the CTC boards , about 10 years ago, Carl Thompson convinced me that a NEW group of conformal coatings were made for high speed computers, with low DA. We used it with the CTC line amp and we still got good results. It was MUCH easier to solder the board, as well. We also improved the substrate from FR-4 to 'Nylon' to Teflon. No use inviting
circuit hook' described by Tektronix 33 years ago or so.
'Circuit hook' was a term coined by Tektronix in the early '70's. It had to do with the DA in the FR-3 or FR-4 circuit board material to change the waveform in the attenuators. DUH! Once you think about it. It was the first serious article on this subject and it was in one of the professional (free to engineers) magazined in the '70's. Charles Hansen of Aire probably has a lead on this so please don't push him away from this thread if you can help it.
Did everyone come to understand that 'circuit hook' is a property of dielectric absorption? You know, change in capacitance with frequency. They CAN'T compensate for this with a regular cap. This caused problems in their attenuators and probes. Think about it. Then think about potential audio problems as well. You never know!
For the 'silent majority': I might not have given enough info as to how and why this is interesting and important.
With RF frequencies, there is a problem with the parasitic capacitance of the resistors and the circuit boards they are wired on.
For example the input of a typical osicilloscope is something like 1meg ohm and 20 pf.
Usually, for high frequency work, we put a passive 10:1 reduction probe with 9meg ohm and 2 pf across it. Do you see the correlation? The caps cancel each others effects at high frequencies and the bandwidth can be many hundred mega-Hz.
It is the same with the internal attenuators that change the range of the input of the scope.
Now, when the parasitic capacitance (in this case, 20pf) changes its value with frequency, because of DA effects, then it is virtually impossible to compensate it with a capacitor of higher quality, because it has the same capactance with frequency, and it will NOT track!
Now think of a circuit board made of cheap materials, with 10's to 100's of resistors, each adding a changing capacitance with frequency. Then, even at audible frequencies, who knows if this could be harmful to the sound.
Remember, 'circuit hook' was visually observable on a scope with one or two resistors. We never see audible distortion in amps until it is too late. We typically look at and measure effects 100-10,000 times lower than this. Now think again at the number of connections to a circuit board, as well as its traces.
With RF frequencies, there is a problem with the parasitic capacitance of the resistors and the circuit boards they are wired on.
For example the input of a typical osicilloscope is something like 1meg ohm and 20 pf.
Usually, for high frequency work, we put a passive 10:1 reduction probe with 9meg ohm and 2 pf across it. Do you see the correlation? The caps cancel each others effects at high frequencies and the bandwidth can be many hundred mega-Hz.
It is the same with the internal attenuators that change the range of the input of the scope.
Now, when the parasitic capacitance (in this case, 20pf) changes its value with frequency, because of DA effects, then it is virtually impossible to compensate it with a capacitor of higher quality, because it has the same capactance with frequency, and it will NOT track!
Now think of a circuit board made of cheap materials, with 10's to 100's of resistors, each adding a changing capacitance with frequency. Then, even at audible frequencies, who knows if this could be harmful to the sound.
Remember, 'circuit hook' was visually observable on a scope with one or two resistors. We never see audible distortion in amps until it is too late. We typically look at and measure effects 100-10,000 times lower than this. Now think again at the number of connections to a circuit board, as well as its traces.
It is almost impossible to completely compensate the R//C - R//C divider. It is much easier to do it for the R-C//C - R-C//C structure. I have known this for at least 25 years 
Regarding that Rogers PCB materials - another thing that helps ...... ....... not pure PTFE, so it is easier to drill and mill .........
Regarding that Rogers PCB materials - another thing that helps ...... ....... not pure PTFE, so it is easier to drill and mill .........
PMA, I am not allowed to be rude to you, so please try not to be rude to me.
Personally, I make a living as a CONSULTANT. That means that I am normally paid for conveying my knowledge of audio electronics. IF I were inclined to GIVE everything away that I normally convey to my clients, then my clients would just 'tune in' and not pay me. I try, with a minimum of words, to convey some of the important aspects of audio design that might not be well known to everyone. I try to back up 'controversial' things, like cleaning leads, etc with my own experience.
I might add that I did NOT start this thread. Others did, and I came in only after much misunderstanding of one of my designs was put here by others. Now, I am trying to add some small, but important, aspects in making (in my opinion) successful audio products. Everyone has the perfect right to use the cheapest solder, the cheapest circuit board, the cheapest caps, resistors, and semiconductors and TRY to make a really successful audio product, due to your brilliant design topology and artful SPICE simulation. Go for it! I have, over the decades, and each and every time, I am pulled back to addressing issues would normally be discounted as unnecessary as a design engineer. When I do pay attention to some details, then extra successful audio products come forth, such as the 'Blowtorch' or the JC-1 power amp.
I can assure you that topology sophistication and simulation alone will not separate the great products from the just-OK products.
Personally, I make a living as a CONSULTANT. That means that I am normally paid for conveying my knowledge of audio electronics. IF I were inclined to GIVE everything away that I normally convey to my clients, then my clients would just 'tune in' and not pay me. I try, with a minimum of words, to convey some of the important aspects of audio design that might not be well known to everyone. I try to back up 'controversial' things, like cleaning leads, etc with my own experience.
I might add that I did NOT start this thread. Others did, and I came in only after much misunderstanding of one of my designs was put here by others. Now, I am trying to add some small, but important, aspects in making (in my opinion) successful audio products. Everyone has the perfect right to use the cheapest solder, the cheapest circuit board, the cheapest caps, resistors, and semiconductors and TRY to make a really successful audio product, due to your brilliant design topology and artful SPICE simulation. Go for it! I have, over the decades, and each and every time, I am pulled back to addressing issues would normally be discounted as unnecessary as a design engineer. When I do pay attention to some details, then extra successful audio products come forth, such as the 'Blowtorch' or the JC-1 power amp.
I can assure you that topology sophistication and simulation alone will not separate the great products from the just-OK products.
john curl said:
John,
I'd like to respectfully point out that all circuit nets are not as affected as others by this and similar effects. This is one of the reasons I keep mentioning that understanding and controlling the layout is a prominent driver of any designs performance.
Regards, Mike.
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