Hi Guys
TUT3 explains this in detail and provides layout drawings for eighteen improved iconic amps to show how it looks in real amps. Intermodulation is exactly the thing avoided by Galactic Grounding and the thing encouraged by a star.
As I said before, if your amps are low gain then you can commit sins of grounding etc and get away with it. I prefer the lowest noise possible as that gives the best tone for hifi and MI.
many things are taught for eons that are simply wrong. For example, the charge of an electron has been known for over 100 years but we still have archaic "conventional current flow" being taught. I only use "real current flow" and that is what is presented in my books. It makes sense.
Have fun
TUT3 explains this in detail and provides layout drawings for eighteen improved iconic amps to show how it looks in real amps. Intermodulation is exactly the thing avoided by Galactic Grounding and the thing encouraged by a star.
As I said before, if your amps are low gain then you can commit sins of grounding etc and get away with it. I prefer the lowest noise possible as that gives the best tone for hifi and MI.
many things are taught for eons that are simply wrong. For example, the charge of an electron has been known for over 100 years but we still have archaic "conventional current flow" being taught. I only use "real current flow" and that is what is presented in my books. It makes sense.
Have fun
TUT is for The Ultimate Tone, a series of books he has written and published for the guitar amplifier hobbyist. Check them out, they hold a world of information, and are well respected.
I hate to be snippy, but next time you think of buying a Gerald Weber book, buy one of Kevin's instead.
I hate to be snippy, but next time you think of buying a Gerald Weber book, buy one of Kevin's instead.
It is often said that, at a star ground, various currents are ‘mingled together’. This has no effect, as I hope the following example shows.
One current loop contains a current of 1 amp. Another loop contains a current of say 0.001 amp. Both loops are initially ‘floating’ (i.e. they have no common voltage reference).
Now connect the two loops together at one arbitrary point (call it a star point) – no change in either current (no effect from 'mingling') – all that happens is that the two loops now have a common reference voltage at the star-point.
One current loop contains a current of 1 amp. Another loop contains a current of say 0.001 amp. Both loops are initially ‘floating’ (i.e. they have no common voltage reference).
Now connect the two loops together at one arbitrary point (call it a star point) – no change in either current (no effect from 'mingling') – all that happens is that the two loops now have a common reference voltage at the star-point.
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If there is an objection to pure star grounding (apart from the obvious physical difficulty of stacking multiple connections) I think it could be along the following lines:
Ground connections provide a common voltage reference for signal voltages, but they also provide signal current return paths. In a pure star ground scheme the small signal return currents for the sensitive early stages of an amp are forced to travel some distance to the star point and back. This makes them susceptible to unwanted interference signals, coupled by mutual induction or stray capacitance, from other circuits in the amp.
Ground connections provide a common voltage reference for signal voltages, but they also provide signal current return paths. In a pure star ground scheme the small signal return currents for the sensitive early stages of an amp are forced to travel some distance to the star point and back. This makes them susceptible to unwanted interference signals, coupled by mutual induction or stray capacitance, from other circuits in the amp.
Controlling the loops for the various groups of circuitry is better than star grounding, only really used in audio... Horowitz and Hill have an interesting view on star grounds as do many others.
Also having lots of spokes from a central point is not the best idea for EMC these days with our RF rich environment.
Also having lots of spokes from a central point is not the best idea for EMC these days with our RF rich environment.
A nice name for marketing purposes, but really a bus ground. I prefer bus grounds. Star grounds tend to be used by people who think they can do grounding without thinking.Struth said:
You just need to ensure that the feedback and the input have the same reference point. In a valve amp this is easy: just ground the OPT secondary at the input stage, not the output stage.Bob Richards said:
That is an ideal star. No real star is a single point. Now take your two loops and connect them together at two nearby points. There will be non-zero resistance and inductance between these two points, so you get a non-zero voltage transfered from one circuit to the other. They become coupled, not merely joined. Star grounding works fine in theory (naive theory, that is, not realistic theory). Real life means that all 'stars' are actually busses, so why not use a well-designed bus instead of a poorly-designed bus?Malcolm Irving said:
That is one way your 'star' is actually a bus. How many people think about the exact order of the tags? How many people realise that the one place your 'star' should not be is right on the chassis?
When building valve RF stuff I use local stars - one per stage - attached to the chassis. When building valve audio stuff I use a bus, with a wire from that to the chassis. Different problems, so different solution.
Hi Guys
Enzo: Thanks for your kind support!
Bob: TUT Guitar Amp Books
DF96: Galactic Grounding is not simply a "bass" ground.
Malcolm: You are incorrect in thinking that the loops do not interact or that this does not happen in a star ground. Real world experience in real amplifiers proves my point, so I am not going to debate with you here.
Just as people railed against the first person to say "the Earth is round", so do people everywhere when they are presented with an idea that is not their own. Galactic Grounding works exactly as I say it does and is universally applicable. A star ground works for certain things but is NOT universally applicable.
Electrically equivalency of schematic connection does not translate in physical connections to "all connection orders being equal". You can demonstrate this for yourself by simply swapping two connections for the rectifier and first filter and have a 10dB change of hum and buzz (two different types of noise).
Horowitz-Hill is disappointing if you want real design info about audio amps. They try to cover all-things-electronic, so do not go very deep into any one area.
I've written about grounding and wiring in detail in TUT3 so that I do not have to rewrite it on an individual basis. That volume has been out since 2003 and all the MI builders have it and have changed some of their techniques for the better. There is still the lethargy of not-invented-here that is endemic and is part of the same nature that resists the round Earth.
Have fun
Enzo: Thanks for your kind support!
Bob: TUT Guitar Amp Books
DF96: Galactic Grounding is not simply a "bass" ground.
Malcolm: You are incorrect in thinking that the loops do not interact or that this does not happen in a star ground. Real world experience in real amplifiers proves my point, so I am not going to debate with you here.
Just as people railed against the first person to say "the Earth is round", so do people everywhere when they are presented with an idea that is not their own. Galactic Grounding works exactly as I say it does and is universally applicable. A star ground works for certain things but is NOT universally applicable.
Electrically equivalency of schematic connection does not translate in physical connections to "all connection orders being equal". You can demonstrate this for yourself by simply swapping two connections for the rectifier and first filter and have a 10dB change of hum and buzz (two different types of noise).
Horowitz-Hill is disappointing if you want real design info about audio amps. They try to cover all-things-electronic, so do not go very deep into any one area.
I've written about grounding and wiring in detail in TUT3 so that I do not have to rewrite it on an individual basis. That volume has been out since 2003 and all the MI builders have it and have changed some of their techniques for the better. There is still the lethargy of not-invented-here that is endemic and is part of the same nature that resists the round Earth.
Have fun
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Don't quite follow that bit. If that is the only place that the audio ground connects to the chassis, what problem is caused?
For me, forums such as this are vehicles (1) for sharing knowledge and (2) for increasing understanding. Posts from ‘gurus’ stating ‘this is how it is’ but unwilling to discuss ‘why it is’ may serve the first objective but don’t help much with the second. 🙂
I have no idea what you mean by bass ground.Struth said:
A set of solder tags on a chassis bolt is not a place, but a set of places. It doesn't connect to the chassis at one point, but a set of points so is sensitive to chassis currents. Much better, if you want a star, to have a star separate from the chassis then connect one wire from the star to a single tag on the chassis; this ensures your 'star' is a better approximation to a genuine star.Malcolm Irving said:
Not that I ever use feedback in any of my guitar amps (I don't), but I hadn't thought of this when I built my Hi-Fi tube amp. Thanks for the info.
And thanks to Struth for the pointer to TUT 3. I sounds like a worthwhile book.
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SY:
"This video is not available from your location"
Perhaps they meant to say not available to or at my location?
"This video is not available from your location"
Perhaps they meant to say not available to or at my location?
Hi Guys
BUSS - should twig from your own post that it was a typo.
I'm no guru, just a guy with minor skills of observation and synthesis. I explained the Galactic Ground above (which is succinct and clear to those with comprehension skills or basic electronics knowledge) and also gave an example of application in a thread about grounding in a power amp. Search my posts.
People like to debate things to show that they DO know something. I don't debate. It is pointless. I can tell you what my experience has shown me and/or what conclusions I've drawn from it but you have the choice to disregard it and reinvent the wheel or try it for yourself. So, I feel that I "know" a few things but that this is practically nothing compared to what others know let alone to what there is to know. I learn a lot from everyone I talk to and from the forums - it is always a two-way street.
There are things that I feel very strongly about as fact, like the tube aging and life expectancy points - those were established long before I was born but I recognise their truth and relay that truth to others to save them spending time and money on such a thing. I abhor the hypocrisy of "experts" who tout the popular view, like that tubes only last six months, just so they can sell tubes to less knowledgeable people.
There is a tonne of free information on my site and a lot more that I've posted on this forum and others. I am trying to make a living from this too, so excuse me if i have to a walk a line sometimes. People who call me for advice get a lot more than they ask for and as I said above, i really do not like having to retype the contents of my books for individual consumption. Call me during my business hours and you can ask anything.
Bob: You were most of the way to having good grounding.
Have fun
BUSS - should twig from your own post that it was a typo.
I'm no guru, just a guy with minor skills of observation and synthesis. I explained the Galactic Ground above (which is succinct and clear to those with comprehension skills or basic electronics knowledge) and also gave an example of application in a thread about grounding in a power amp. Search my posts.
People like to debate things to show that they DO know something. I don't debate. It is pointless. I can tell you what my experience has shown me and/or what conclusions I've drawn from it but you have the choice to disregard it and reinvent the wheel or try it for yourself. So, I feel that I "know" a few things but that this is practically nothing compared to what others know let alone to what there is to know. I learn a lot from everyone I talk to and from the forums - it is always a two-way street.
There are things that I feel very strongly about as fact, like the tube aging and life expectancy points - those were established long before I was born but I recognise their truth and relay that truth to others to save them spending time and money on such a thing. I abhor the hypocrisy of "experts" who tout the popular view, like that tubes only last six months, just so they can sell tubes to less knowledgeable people.
There is a tonne of free information on my site and a lot more that I've posted on this forum and others. I am trying to make a living from this too, so excuse me if i have to a walk a line sometimes. People who call me for advice get a lot more than they ask for and as I said above, i really do not like having to retype the contents of my books for individual consumption. Call me during my business hours and you can ask anything.
Bob: You were most of the way to having good grounding.
Have fun
Your on the money there. V1 in my main harp amp is about 50 years old and been in use for it least 25 of those years (all be it in a radiogram) it's just run in nice now. 😀
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