John Curl's Blowtorch preamplifier

[stinius]

Re: re re re

Why on earth does everyone think of earth as earth
regards
max
ps aren't our nuts cracked by electrons

You are so right, we ( I have worms so I can say we, if you are a King you can also say we) think it's important to differ between signal ground "earth" AC ground "earth" and the "Earth"

Stinius

 

[albin]

I agree

yes

 

[jneutron]

Re: Re: Re: Re: Re: Re: Re: unanticipated benefit?

I'm not sure where you are driving.
Such gross mistakes, as you mentioned, may happen, however, they are not regularly, or often, arrived at by competent engineers and technicians, such as I worked with for the past 47 years.

Such mistakes are made by the best engineers and technicians.

That is why people like Tom Van Doren and Bill Whitlock are in such demand.

Anyhow, I fail to see what such mistakes and wrong conclusions have to do with the present thread. I'm under the impression that this thread is about better designing audio gear.

Designing better audio gear is not just about making a box that has excellent specifications but does not work in the real world. Unfortunately, in the real world, the equipment may be assulted by things such as ground loop currents. My discussion is about those currents as caused by induction, and the induction based coupling within the equipment by that current. So the topic is indeed relevant to the discussion at hand..

It is the first time you mention here "external" induction loops.

No it is not. If you go back ten, twenty posts, you will see I have referred to external loops many many times...if you go back far enough, you will see a drawing which shows an amp, a preamp, a duplex outlet, two power supply wires, and an IC (that'd be post number 10653).. It should be quite obvious that all of those components are part of an induction loop that is most certainly outside or "external" to the equipment. "Duplex outlet" is the name of the wall outlet on this side of the pond...

Again, I fail to see what it has to do with the present thread.

I repeat, if the equipment is not designed to handle the ground loop currents, then the alternative is to remove them at the source..or live with them.

Anyhow, when an audio setup operates below the expected performance, obviously the user should first locate the source, or cause, of the bad performance. Most intelligent high end sound setups are quite apt to it. Those are not should hire a competent engineer or technician to do it.

I've seen the results of real life with safety bonded equipment and ground loops. And I've also had to deal with engineers, technicians, sound engineers, physicists, scientists, many who did not understand the basic issue of induced currents.

That is why T Van Doren makes such a good living...he teaches this stuff to all the high level engineer type guys...

Cheers, John

ps..one of my biggest fears is the people who disconnect the safety ground...alas, sometimes they are not presented better options.

 

[john curl]

People like to talk about what they know about. We are off the subject of designing better audio circuitry specifically, although grounding certainly is important. I just don't find anything put forward here as being immediately useful. I live in an apartment that only has 2 wires actually working, and the third wire ground is floating. It seems to work OK.

 

[stinius]

People like to talk about what they know about. We are off the subject of designing better audio circuitry specifically, although grounding certainly is important. I just don't find anything put forward here as being immediately useful. I live in an apartment that only has 2 wires actually working, and the third wire ground is floating. It seems to work OK.

Yes, that is why it's important to differ betwen the different "earths" and "grounds"

Stinius

 

[jneutron]

People like to talk about what they know about. We are off the subject of designing better audio circuitry specifically, although grounding certainly is important. I just don't find anything put forward here as being immediately useful. I live in an apartment that only has 2 wires actually working, and the third wire ground is floating. It seems to work OK.

Well excuuuuse me...
Some people have all the luck...

While I understand the need for the safety ground, I certainly don't have to like it..yuk..And you certainly seem to have solved the safety ground problem, eh?

As I said before, you solved your problems with more supplies..certainly one way to skin a cat..

Getting the same performance via e/m trickery....that's the fun part..well, elegant also, but fun...

Cheers, John

 

[stinius]

Well excuuuuse me...
Some people have all the luck...

While I understand the need for the safety ground, I certainly don't have to like it..yuk..And you certainly seem to have solved the safety ground problem, eh?

As I said before, you solved your problems with more supplies..certainly one way to skin a cat..

Getting the same performance via e/m trickery....that's the fun part..well, elegant also, but fun...

Cheers, John

Don't be so angry.

I can see that you know what you are talking about, and I understand the frustration, but anyway.

Stinius

 

[Joshua_G]

Re: Re: Re: Re: Re: Re: Re: Re: unanticipated benefit?

Such mistakes are made by the best engineers and technicians.

Indeed, however, to my experience, only seldom. The exception is not the rule.

Designing better audio gear is not just about making a box that has excellent specifications but does not work in the real world.

Sorry, it is the other way around. The more home environment is polluted by EMI, HFI and RFI – the more important it is to better design the audio equipment box for shielding from such interference, along with all other aspects of the gear.

Unfortunately, in the real world, the equipment may be assulted by things such as ground loop currents.

Indeed, however this is no excuse for being sloppy in shielding the equipment from EMI and RFI.
External ground loops are to be dealt with at the set up.

My discussion is about those currents as caused by induction, and the induction based coupling within the equipment by that current. So the topic is indeed relevant to the discussion at hand..

To my view, what's relevant to this thread is the protection that can be given to the equipment at the stages of design and build. What you are saying is that there are phenomena that can't be dealt with at the stage of design. Indeed, there are such phenomena, however, their existence is no excuse for being sloppy in the shielding that can be done at the stage of design.

No it is not. If you go back ten, twenty posts, you will see I have referred to external loops many many times...

My apology. Indeed, in the past 3 weeks or so I browsed this thread from page 1, however, I don't remember what every participant here said in past messages. This is why I saved all text that I found usufel.

I repeat, if the equipment is not designed to handle the ground loop currents, then the alternative is to remove them at the source..or live with them.

Again, well designed equipment does not have inner ground loops and it is well shielded from external radiated and emitted interference. These are some of the marks of well designed equipment, along with sound quality considerations.

Yet again, equipment can be designed to avoid internal ground loops. External ground loops should be dealt with externally.

I do ask you, please be clear, as I fail to grasp your point – what does external ground loops has to do with the equipment design? Do you have any suggestions as to better design audio gear so that it will have better immunity from external ground loops? If yes – I'm all ears, as I'm here to learn. If not – what is your point?

I've seen the results of real life with safety bonded equipment and ground loops. And I've also had to deal with engineers, technicians, sound engineers, physicists, scientists, many who did not understand the basic issue of induced currents.

In the technical electronic culture I grew up to and worked in – such cases are the exception. Not the rule.

Anyhow, what are your suggestions as to how to better design audio gear in the light of the above?

 

[Joshua_G]

While I understand the need for the safety ground, I certainly don't have to like it.

So, what are your suggestions?

 

[stinius]

"I do ask you, please be clear, as I fail to grasp your point – what does external ground loops has to do with the equipment design? Do you have any suggestions as to better design audio gear so that it will have better immunity from external ground loops? "

You didn't ask me, but it's a lot of ways to exclude external ground loops to interact the sound and make hum.

And as I see it it's the external ground loops that course the big problems.

Stinius

 

[jneutron]

Don't be so angry.

I can see that you know what you are talking about, and I understand the frustration, but anyway.

Stinius

Angry?? Que??

I'm certainly not angry..guess I shoulda used a smiley or sumptin...😀 😀 😀 😀 😀 😀 😀 😀 😀 😀 😀 😀

I'd sprinkle em around my previous posts if I could...this isn't something to be angry about...

Cheers, John

 

[stinius]

OK 😀

Fine

Cheers

Stinius

 

[Joshua_G]

[B
You didn't ask me, but it's a lot of ways to exclude external ground loops to interact the sound and make hum.

And as I see it it's the external ground loops that course the big problems.
[/B]

Indeed, many times it is so.

My question is about what can be done about it at the stage of the equipment design?

Alternately, do you think that in the light of the above fact we should put less attention to the equipment box's design?

 

[jneutron]

Re: Re: Re: Re: Re: Re: Re: Re: Re: unanticipated benefit?

Sorry, it is the other way around. The more home environment is polluted by EMI, HFI and RFI – the more important it is to better design the audio equipment box for shielding from such interference, along with all other aspects of the gear.

That explains where we disconnected...we are agreeing.

Indeed, however this is no excuse for being sloppy in shielding the equipment from EMI and RFI.
External ground loops are to be dealt with at the set up.

I've already stated that. And if you look at the thread grounding, I've pointed out two very easy ways to do such.

The problem comes when those options don't fix it all. Then, it boils down to the equipment design.

To my view, what's relevant to this thread is the protection that can be given to the equipment at the stages of design and build. What you are saying is that there are phenomena that can't be dealt with at the stage of design.

No, that's not quite what I said. What I said is the equipment designer has little control over the external loops, and has to try to get the equipment to ignore the resultant currents.

My apology. Indeed, in the past 3 weeks or so I browsed this thread from page 1, however, I don't remember what every participant here said in past messages. This is why I saved all text that I found usufel.

What, you can't remember 90 posts back?? (whoa, it was quite a ways back, wasn't it...)

Again, well designed equipment does not have inner ground loops and it is well shielded from external radiated and emitted interference. These are some of the marks of well designed equipment, along with sound quality considerations.

I leave the "sound quality considerations" to others. Some designers believe that a pc trace that is not straight, placed over a complete ground plane, is well behaved....it is not. It has built in loops at low frequencies. And star grounds are certainly not the cat's meow.. They have their inductive issues.

I do ask you, please be clear, as I fail to grasp your point – what does external ground loops has to do with the equipment design? Do you have any suggestions as to better design audio gear so that it will have better immunity from external ground loops?

External ground loops force the equipment to have to deal with the induction.

There are methods to transport the currents without creating external fields or coupling. And methods to transport currents without generating internal fields...little hideaways you can place signal lines in..

Anyhow, what are your suggestions as to how to better design audio gear in the light of the above?

Ah, I've posted many that I've used...the problem is, people like you...

You require proof..😀

Hence the other thread, where I'm putting together the test equipment to force, find, and see what's going on..

So, what are your suggestions?

Tomorrow...outta time today..

Cheers, John

 

[Joshua_G]

I'm certainly not angry..guess I shoulda used a smiley or sumptin...😀 😀 😀 😀 😀 😀 😀 😀 😀 😀 😀 😀

I'd sprinkle em around my previous posts if I could...this isn't something to be angry about...

Good.

However, do you have any suggestion to deal with that problem at the stage of design?

 

[Joshua_G]

Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: unanticipated benefit?

Tomorrow...outta time today..

Good. I'll wait, since I'm here to learn.

 

[bear]

mr. neutron,

i am most interested in your take on this "ground loopy" thing, and look forward to reading everything you have to say on the subject. I do not think it is well understood in the main, and is oft quite confusing to even begin to think about properly... don't care where the thread is, as long as it bears fruit.

Btw, as I posted in ur thread, I think it properly belongs in this Solid State section, not the "parts" section, although it is labeled "electronics" as well - doubt if it gets the same readership as does this one?

joshua, please tell us more about what sort of area your experience is in? you've made a claim of 47 years of experience with nary a mistake by those with whom you work with? I think maybe there are things you can bring forward that might be interesting and good for all of us here regarding these design matters?


_-_-bear

 

[PMA]

People like to talk about what they know about. We are off the subject of designing better audio circuitry specifically, although grounding certainly is important. I just don't find anything put forward here as being immediately useful.

In my opinion and experience, grounding and EMI suppression are VERY important for the resulting sound (very high influence ranking 😀) .

People like to talk about what they know about, but the same people are easily able to bury an excellent audio circuit just for the reason they do not understand grounding and EMI issue.

 

[jan.didden]

Hate to admit it Pavel, but I actually agree with you 😉 .
If I build a Blowtorch, with all recommended parts and layout and wiring, I could still easily mess it up completely by getting the grounding etc wrong.

Jan Didden

 

[Joshua_G]

joshua, please tell us more about what sort of area your experience is in? you've made a claim of 47 years of experience with nary a mistake by those with whom you work with? I think maybe there are things you can bring forward that might be interesting and good for all of us here regarding these design matters?

Thank you, Bear, however I doubt that Ill have much to contribute here, as I'm a self-learned electronics technician, not a qualified engineer.
As for my background.
I studied in technical high school, but I didn't graduate, since I was I was interested in electronics much more than in all the other areas, like history and the rest.
In the army I served as a Teleprinter tech. Then I worked for the Israeli broadcasting service as a tech for about 10 years. Then for many years I worked as a tech, servicing audio and video consumer appliance for various labs. About 6 years ago I was hired as tech to a startup high-tech company which developed a wireless modem for satellite data communication. However, as I started work there, I was horrified by some gross mistake the development engineers did. I pointed out those mistakes and very soon my duties included both those of a tech and of an engineer. However, I don't have much experience in designing audio circuits.

Now I'm retired. Recently I upgraded my stereo and home theater system and I was looking for good DAC with a moderate cost. I found a DIY kit for a DAC which suppose to be very good. I ordered this kit, to be shipped few weeks later. While waiting, I thought about how to improve that's kit performance. I started looking for aluminum metal box, for a very quiet PSU (which I found on the net) and for a good I/V amp, better that the one included in that kit. I also ordered very good (and expansive) RCA and XLR sockets. So I googled for "low noise OpAmp" and landed here, in this thread. Now I started design I/V amp, based on the principles presented by John Curl, namely, folded cascode JFET first stage and JFET/MOSFET second stage with servo. I hope I'll manage to come up with something that will sound decent.