If you mean: do you, Andrew, do an excellent job regarding "putting in few words,and in a clear manner" the subject of grounding ? imo, yes. Does everybody understand what you are saying regarding grounding ? Probably not everybody. But this world isn't perfect Andrew, we both know that.
With kind regards,
Klaas
AndrewT said:
Thanks Andrew,
please note that my statement was formed as a question, as I am not sure. The question continues....
What if your sec. ground were not tied to chassis, and one of your secondary live wires touched chassis? Wouldn't this either cause a hazard or at the very least other gear to smoke instead of just popping the equip. fuse? Although the secondaries are isolated, would not the shield on an interconnect to a pre-amp etc. cause a path, and a possible issue? As soon as you plug something else in, isn't the isolation very likely eliminated, especially if the architecture of the second device is not known? Thanks!
As long as your deivices either have the UL or similar label there is little to worry about... Also if you are concerned about your own DIY devices then I would reccomend that you research the UL codes and wire them to that standard. But you are right in your assumption of even a secondary live wire touching a non-grounded chassis. I'm thinking tube gear of older days where the transformer secondaries have 400 to 500 volt or more secondaries! That is a very dangerous situation indeed... thats just another way that folks get electrocuted! Also keep in mind that almost all devices with a "live" chassis are in plastic cabinets and that the switches and anything else protruding into the cabinet or chassis also has to be UL or equivelent... or better... approved.
Mark
P.S. A very good example of that are all of my early pre-1950 television sets. These sets have multiple lethal voltages in them with some voltages not even refrenced to the main power supply ground. They had neither a polorized plug nor a grounded chassis(they do now though!). Most of them also lacked any type of safety fuse! (they have that now too!) Most old radios are also like this.....
Mark
P.S. A very good example of that are all of my early pre-1950 television sets. These sets have multiple lethal voltages in them with some voltages not even refrenced to the main power supply ground. They had neither a polorized plug nor a grounded chassis(they do now though!). Most of them also lacked any type of safety fuse! (they have that now too!) Most old radios are also like this.....
Hi,
a lot later than pre 1950.
Our first TV bought in 1959 was all valve and used a large mains connected multi tapped resistor to generate the various voltages needed to run the TV. This was to save the cost of a large mains transformer. This practive went on into at least the 60s and maybe even the 70s. It has disappeared with the advent of SS electronics.
Some current (2006) low power equipment follows a similar practice of avoiding the cost of an isolated transformer secondary. eg. resistor and capacitor connected direct to mains feeding a diode to generate DC to run small amps (computer speakers), detectors, LEDs, relay drivers, etc.
A secondary that is isolated from chassis is exactly that.
Connect one end, by accident or deliberately, to chassis and that end is then referenced to safety ground and the other end is then pulled to the secondary output voltage. The equipment may not operate properly linked up this way and may blow a fuse. But it should not blow up any connected equipment and certainly must not endanger the user.
This isolation is why so many designers do not connect audio ground to safety earth. That includes the RCA ground which should also be isolated from chassis.
a lot later than pre 1950.
Our first TV bought in 1959 was all valve and used a large mains connected multi tapped resistor to generate the various voltages needed to run the TV. This was to save the cost of a large mains transformer. This practive went on into at least the 60s and maybe even the 70s. It has disappeared with the advent of SS electronics.
Some current (2006) low power equipment follows a similar practice of avoiding the cost of an isolated transformer secondary. eg. resistor and capacitor connected direct to mains feeding a diode to generate DC to run small amps (computer speakers), detectors, LEDs, relay drivers, etc.
A secondary that is isolated from chassis is exactly that.
Connect one end, by accident or deliberately, to chassis and that end is then referenced to safety ground and the other end is then pulled to the secondary output voltage. The equipment may not operate properly linked up this way and may blow a fuse. But it should not blow up any connected equipment and certainly must not endanger the user.
This isolation is why so many designers do not connect audio ground to safety earth. That includes the RCA ground which should also be isolated from chassis.
Marc, asking why is what people do to learn.I value Andrew's opinion because his reasoning makes sense to me, nothing else.
If Albert Einstein would tell me to take a bath and throw in a mains-connected wire to create some nice extra bubbles, i would tell him to take a hike.
Andrew and Mark, i basically know what "proper galvanic isolation from AC mains" means. Thats why i treat the AC voltage coming from a Variac as if it were 220v .
With kind regards,
Klaas
If Albert Einstein would tell me to take a bath and throw in a mains-connected wire to create some nice extra bubbles, i would tell him to take a hike.
Andrew and Mark, i basically know what "proper galvanic isolation from AC mains" means. Thats why i treat the AC voltage coming from a Variac as if it were 220v .
With kind regards,
Klaas
HI Bikehorn,
Sorry, I did not. For some reason I'm not sure of when I delete any DUY mail it places the mail in the spam mailbox. I have to keep taking it back out of the smap mail box fomr time to time. So far Yahoo has not had any good answer for this glitch.
Try ksa50ampatyahoo.com and see if that works...
Mark
Sorry, I did not. For some reason I'm not sure of when I delete any DUY mail it places the mail in the spam mailbox. I have to keep taking it back out of the smap mail box fomr time to time. So far Yahoo has not had any good answer for this glitch.
Try ksa50ampatyahoo.com and see if that works...
Mark
Finally,
I was able to listen to my 'krell' is progress. Aside from a little buzz and some wierd on-off noises...wow! Great control, super bass, and great highs. It's best when biased hard (there's a surprise). I can see why this is a 'slightly' popular project.
regarding my issues; The buzz I think is due to a crappy toroid. The on/off squeal is a mystery to me though....
I was able to listen to my 'krell' is progress. Aside from a little buzz and some wierd on-off noises...wow! Great control, super bass, and great highs. It's best when biased hard (there's a surprise). I can see why this is a 'slightly' popular project.
regarding my issues; The buzz I think is due to a crappy toroid. The on/off squeal is a mystery to me though....
on/off squeal...transformers...
Hi,
A couple of times in the past with other amps I built I've had the 'off' squeal. While I never really found the specific cause, it showed up as a low voltage instability, and seemed strongly correlated with the 2 rails collapsing at different rates. Sometimes the cure was as simple as laying out I/O/Power cables 'just so', shielding etc.
In any case beware, the low squeal you can hear is not that big a deal, but it could hide a higher level ultrasonic component...if you have a scope I'd check it out...you probably have some nice speakers...
Transformers buzzing drives me nuts, they should be seen and not heard. Distortion in the mains is often a culprit, but not always...I've rewound an unpotted toroid before, it had a couple of turns that had been left too loose and were moving under load...if I were braver I'd figure out how to vacuum pot the darn things, at least then nothing can change. Adcom seems to like potting theirs, some sort of epoxy, all enclosed in a soft steel case, works quite well in my experience.
Ultimately the transformer, along with the rectifier diodes it is in series with the output. Presumably it has as much influence on the sound as any other ~100ft long run of wire.
HTH
Stuart
Hi,
A couple of times in the past with other amps I built I've had the 'off' squeal. While I never really found the specific cause, it showed up as a low voltage instability, and seemed strongly correlated with the 2 rails collapsing at different rates. Sometimes the cure was as simple as laying out I/O/Power cables 'just so', shielding etc.
In any case beware, the low squeal you can hear is not that big a deal, but it could hide a higher level ultrasonic component...if you have a scope I'd check it out...you probably have some nice speakers...
Transformers buzzing drives me nuts, they should be seen and not heard. Distortion in the mains is often a culprit, but not always...I've rewound an unpotted toroid before, it had a couple of turns that had been left too loose and were moving under load...if I were braver I'd figure out how to vacuum pot the darn things, at least then nothing can change. Adcom seems to like potting theirs, some sort of epoxy, all enclosed in a soft steel case, works quite well in my experience.
Ultimately the transformer, along with the rectifier diodes it is in series with the output. Presumably it has as much influence on the sound as any other ~100ft long run of wire.
HTH
Stuart
OK,
Thanks to all. I got my issues worked out and I gotta say, WHAT A GREAT AMP! I had issues in the front end board grounding. Once I found it all the problems went away! I still like my a30 better in the mids/highs but this is a great all-around amp (when biased hard).
How can I get my hands on another set of Pinky boards? I want to build one for a friend as a housewarming
gift. I know he'll like it. I only ask about the pinkmouse boards because I know then pretty well now . If there are no pink boards out there I certainly wouldn't mind a set of Mark's.
Thanks
Marc
Thanks to all. I got my issues worked out and I gotta say, WHAT A GREAT AMP! I had issues in the front end board grounding. Once I found it all the problems went away! I still like my a30 better in the mids/highs but this is a great all-around amp (when biased hard).
How can I get my hands on another set of Pinky boards? I want to build one for a friend as a housewarming
gift. I know he'll like it. I only ask about the pinkmouse boards because I know then pretty well now . If there are no pink boards out there I certainly wouldn't mind a set of Mark's.Thanks
Marc