Ref post #7552
I was very disappointed reading this post, in particular the statement
"so I concluded that there was no great risk in dispensing with this wretched plug fuse"
The concern here is SAFETY.
It is totally irresponsible putting this kind of statement on a DIY
(or any other) site. In fact this breaks the forum rules (number4).
In the UK we have a 230 Volt system that requires that the mains plug has a fuse up to 13 Amp rating, the fixed wiring is protected by a 30Amp or 32Amp HRC fuse or circuit breaker.
To short out the 13A plug fuse leaves a 32Amp protection device as the only protection against overload, these HRC type fuses or breakers are meant to carry the rated current X 1.6 for half an hour, (45Amps or so).
Such a high and prolonged current on relatively small domestic equipment and flex is obviously a serious fire hazard.
Further this kind of prolonged fault condition can be a serious shock hazard, as the earth potential on the local circuits within the Premises can be elevated to dangerous levels.
Prolonged fault condition, here meaning the time delay before the
protection device (fuse or breaker) disconnects.
It is not acceptable to state further in the post
"Returning to the unit's mains input protection, which I believe
Should be retained whatever (unfortunately), especially if most other protection is dispensed with"
As some sort of very weak disclaimer, what you need to do is rethink this post and edit it accordingly. I see visions of DIYers with little experience/knowledge following this advice, as a tweak, or connection of their latest possibly unsafe projects in this way, and here I am not just talking about the UK mains, but fuse protection in general
I was very disappointed reading this post, in particular the statement
"so I concluded that there was no great risk in dispensing with this wretched plug fuse"
The concern here is SAFETY.
It is totally irresponsible putting this kind of statement on a DIY
(or any other) site. In fact this breaks the forum rules (number4).
In the UK we have a 230 Volt system that requires that the mains plug has a fuse up to 13 Amp rating, the fixed wiring is protected by a 30Amp or 32Amp HRC fuse or circuit breaker.
To short out the 13A plug fuse leaves a 32Amp protection device as the only protection against overload, these HRC type fuses or breakers are meant to carry the rated current X 1.6 for half an hour, (45Amps or so).
Such a high and prolonged current on relatively small domestic equipment and flex is obviously a serious fire hazard.
Further this kind of prolonged fault condition can be a serious shock hazard, as the earth potential on the local circuits within the Premises can be elevated to dangerous levels.
Prolonged fault condition, here meaning the time delay before the
protection device (fuse or breaker) disconnects.
It is not acceptable to state further in the post
"Returning to the unit's mains input protection, which I believe
Should be retained whatever (unfortunately), especially if most other protection is dispensed with"
As some sort of very weak disclaimer, what you need to do is rethink this post and edit it accordingly. I see visions of DIYers with little experience/knowledge following this advice, as a tweak, or connection of their latest possibly unsafe projects in this way, and here I am not just talking about the UK mains, but fuse protection in general
Hi,
I am not going to argue here, but this is simply not stating the matter fully or correctly, unfortunately.
The high value consumer-unit protection you refer you is followed by an individual circuit MCB or RCD (of which there are usually many in a domestic unit) usually of a max of 16A, or in other cases 6A.
Dedicated cooker and water-heater circuits (which are not in discussion here) are higher current protection, though.
My comments will only affect the short cable between amp and wall socket, and will then be protected by these individual breakers, which will doubtless fire long before any 13A plug fuse would have as I well know, as they are such slow devices in reaction.
This puts us on a similar risk basis to the majority of the rest of the world, and I also advised that individuals should consider their own position, but this is what I have carried out.
Regards,
I am not going to argue here, but this is simply not stating the matter fully or correctly, unfortunately.
The high value consumer-unit protection you refer you is followed by an individual circuit MCB or RCD (of which there are usually many in a domestic unit) usually of a max of 16A, or in other cases 6A.
Dedicated cooker and water-heater circuits (which are not in discussion here) are higher current protection, though.
My comments will only affect the short cable between amp and wall socket, and will then be protected by these individual breakers, which will doubtless fire long before any 13A plug fuse would have as I well know, as they are such slow devices in reaction.
This puts us on a similar risk basis to the majority of the rest of the world, and I also advised that individuals should consider their own position, but this is what I have carried out.
Regards,
Burbeck, I tend to agree with you in principle. However, Bobken, I also note and understand more fully what you actually do, and I tend to agree as well.
The problem is casually dismissing fuses and what they do well. They tend to prevent fires.
Products have not really improved since I worked at UL, 46 years ago, because what is REALLY guarded against is human mistakes and folly, not just equipment breakdown. This remains about the same at this time, and this can cause fires, IF there is no good way of detecting a sustained overcurrent, beyond what the equipment can handle.
Of course, circuit breakers, which we have used in pro audio designs since the early '70's or even before, are actually better than fuses in domestic equipment as well, as long as you learn to work around the limitations of the circuit breaker itself. For example, a typical circuit breaker will have a nonlinear inductance of 2 UH or so. This will ring, if not damped, especially in DC circuits. Thermal breakers are not very fast, BUT they seem to have less compromise internally, more like a dissimilar metal connection, than much else. Both are better than fuses and what we have used when able in our audio designs, as well.
So long as SOMETHING is used, I am happy, without being a 'safety wonk' and crying about the removal of a 3rd wire or something, in order to break a ground loop. I always thought that this was 'overkill' in most audio equipment, just like some in England find the connector fuse. Most Americans would think so, as well.
The problem is casually dismissing fuses and what they do well. They tend to prevent fires.
Products have not really improved since I worked at UL, 46 years ago, because what is REALLY guarded against is human mistakes and folly, not just equipment breakdown. This remains about the same at this time, and this can cause fires, IF there is no good way of detecting a sustained overcurrent, beyond what the equipment can handle.
Of course, circuit breakers, which we have used in pro audio designs since the early '70's or even before, are actually better than fuses in domestic equipment as well, as long as you learn to work around the limitations of the circuit breaker itself. For example, a typical circuit breaker will have a nonlinear inductance of 2 UH or so. This will ring, if not damped, especially in DC circuits. Thermal breakers are not very fast, BUT they seem to have less compromise internally, more like a dissimilar metal connection, than much else. Both are better than fuses and what we have used when able in our audio designs, as well.
So long as SOMETHING is used, I am happy, without being a 'safety wonk' and crying about the removal of a 3rd wire or something, in order to break a ground loop. I always thought that this was 'overkill' in most audio equipment, just like some in England find the connector fuse. Most Americans would think so, as well.
john curl said:
Hi John,
I couldn't have said this better myself, and have never intended to indicate otherwise.
I knew that my 'fuse revelations' would ruffle some feathers (it has done before here), which is why I took a day or so to carefully consider my remarks, together with any affect they might have, before I posted anything.
Indeed I said clearly up front that I take this subject very seriously from the safety and the sonic effects aspects, and unlike some others I have NEVER suggested that all fuses (or proper alternative protection) should be dispensed with, so I was a little surprised that my comments were pounced upon, somewhat out of full context, when some others appeared to go 'unscathed'.
I carefully separated out the peculiar UK 'mains plug fuse' issue when I wrote, and did not make any suggestions/recommendations relating to this topic at all, and I even advised affected readers (ONLY in the UK) to consider this particular matter for themselves as the consequences would be theirs to bear. I simply and quite factually related what I had discovered in this respect, in case it was of interest to anyone, and I do not believe that I offended against any Forum rules in doing this on a worldwide Audio forum.
My other specific suggestions did arise from the fact that some posters on this thread (and several private mails I received) requested me to 'expose' these thoughts based on my listening and observation experiences, which few will ever have the time or inclination to conduct for themselves, so that is what I did. Having already received some words of thanks privately, it seems that my time was not entirely wasted.
I am not advocating recklessness as I also said before, and I am sorry if my sincere efforts and a few hours of my time have resulted in someone being upset or "disappointed".
Regards,
Bobken, your posts was very informative and I don't see anything wrong with what you said.
Thank you.
Thank you.
hi Bobken,
with regard to your statment
"The high value consumer-unit protection you refer you is followed by an individual circuit MCB or RCD (of which there are usually many in a domestic unit) usually of a max of 16A, or in other cases 6A."
this is not correct, the vast majority of final circuits in the UK are ' ring main circuits', and such are fused/breaker at 30Amp or 32Amp. that is double what you say along with the corresponding fault current.
what I have said are facts and are required by 'code'. IEE Wiring Regulations.
i do not wish to carry this on any further in this thread, if you must continue then please make it within a private communication, I think that would be the best thing to be fair to everyone.
This is not to distract from your valuble input on this forum, having personaly given me advise in the past.
hi John,
I thought I would apolagise to you regarding the above posts ETC, as it dont hurt to creep to the right people either, and may I offer a thank you for your many contributions here too.
with regard to your statment
"The high value consumer-unit protection you refer you is followed by an individual circuit MCB or RCD (of which there are usually many in a domestic unit) usually of a max of 16A, or in other cases 6A."
this is not correct, the vast majority of final circuits in the UK are ' ring main circuits', and such are fused/breaker at 30Amp or 32Amp. that is double what you say along with the corresponding fault current.
what I have said are facts and are required by 'code'. IEE Wiring Regulations.
i do not wish to carry this on any further in this thread, if you must continue then please make it within a private communication, I think that would be the best thing to be fair to everyone.
This is not to distract from your valuble input on this forum, having personaly given me advise in the past.
hi John,
I thought I would apolagise to you regarding the above posts ETC, as it dont hurt to creep to the right people either, and may I offer a thank you for your many contributions here too.
as i have said,
everythingback to the mains generator is in the audio signal path.
but, we have opportunity to engineer solutions at the power supply, thus isolating/mimising the fuse/other effects.
everythingback to the mains generator is in the audio signal path.
but, we have opportunity to engineer solutions at the power supply, thus isolating/mimising the fuse/other effects.
myhrrhleine said:
Including things like earth magnetism or generators fueled by U235? 🙄
Anyhow, if someone experiences any effect of the main fuses on his audio equipment, then something is terrible wrong with either that piece of equipment (most unlikely) or someone's psyche (most likely).
Cheers,
Edmond.
myhrrhleine said:
Edmond Stuart said:
I agree with you both, especially post by myhrrhleine
My own interesting solution of current sensing of power supply wires
+ a good low resistance relays in power supply path
would be one such solution.
We do not often see this way.
It is a bit advanced compare to putting ordinary fast fueses in power supply / output.
Like John Curl prefers it 😉
Edmond points out our limited hearing / the minute effects of a fuse.
I second your opinion that no man alive would notice
if there is a fuse in the path .. or not.
Anyone claiming other opinion ( like our very valuable member John Curl maybe )
- you go do your homework and some controlled ABX Blind Test.
Then we will ba able see if your subjective opinion was valid.
I have posted already one little ABX Testing apparatus you can do alone, at home:
http://www.diyaudio.com/forums/showthread.php?postid=1567815#post1567815
quoting myself, i am
beecause i am good, after 3.000 posts in this forum i have learned something 😉
It always reduces to 'double blind' with some people. They just don't trust their ears. It doesn't matter whether it is fuses or circuit breakers, just SOMETHING to detect a potential fire producing short. This is what I am concerned with as far as safety.
However, I believe that fuses make a significant difference in most audio equipment. This is the sort of thing that separates the serious from the indifferent listener. It is just these sort of things that make a Blowtorch separate from a Dyna preamp. If you cannot accept differences such as this, then why bother with audio at all?
However, I believe that fuses make a significant difference in most audio equipment. This is the sort of thing that separates the serious from the indifferent listener. It is just these sort of things that make a Blowtorch separate from a Dyna preamp. If you cannot accept differences such as this, then why bother with audio at all?
Everyone,
Please be safe.
Just a couple notes on freightening things I've seen:
Typically, tweeters in pro audio and music insrtument speaker cabinets are protected with 12V automotive dome lamps. Just about the perfect non-linear resistor. We would use two in parallel for just the right protection level in bass guitar cabinets. If the cat on stage was wailing on his rig, you could see the lamps lighting up the insides of the cabinets through the surounds and vents. On two occasions I've seen the lamps burst and light the stuffing in the cabinet on fire. Poly fill damping material burns fast, and both times the cabinets were put out with fire extinguishers. I never ever, ever put flamible stuffing in a cabinet-fiber glass only.
I was working on a 500W amplifier that wasn't working right. I opened the schematic to try and figure out what was hapening, and a few seconds later -bang- a capacitor blew a perfect wad cutter hole where the can went through the paper draped over the amplifier. I wear safety glasses all the time when working on circuits now.
UL, CSA, Semko, TUV are all basically insurance underwriters. If you pay them to underwrite your product, they'll make you modify it until they think it's safe. If you get sued, they come to court with you to vouch that your product was safe, and the user was the idiot.
In Europe the safety concern is electrocution with those scarry 220-240VAC mains. Here in the States, where currents are twice as high, fire in the building wiring is the main concern. Those wacky UK folks have loop mains (both ends of the wire go back to the fuse box) so they can have the high currents of US circuits with 240VAC. Yikes! That's why they put fuses in the plug ends of the power cords there.
As good as somthing sounds without mains protection, please think about what can happen if somthing goes wrong. Mabye you're a horible ugly bachelor, but how about the kids upstairs, etc.
Regards,
Mlise
Please be safe.
Just a couple notes on freightening things I've seen:
Typically, tweeters in pro audio and music insrtument speaker cabinets are protected with 12V automotive dome lamps. Just about the perfect non-linear resistor. We would use two in parallel for just the right protection level in bass guitar cabinets. If the cat on stage was wailing on his rig, you could see the lamps lighting up the insides of the cabinets through the surounds and vents. On two occasions I've seen the lamps burst and light the stuffing in the cabinet on fire. Poly fill damping material burns fast, and both times the cabinets were put out with fire extinguishers. I never ever, ever put flamible stuffing in a cabinet-fiber glass only.
I was working on a 500W amplifier that wasn't working right. I opened the schematic to try and figure out what was hapening, and a few seconds later -bang- a capacitor blew a perfect wad cutter hole where the can went through the paper draped over the amplifier. I wear safety glasses all the time when working on circuits now.
UL, CSA, Semko, TUV are all basically insurance underwriters. If you pay them to underwrite your product, they'll make you modify it until they think it's safe. If you get sued, they come to court with you to vouch that your product was safe, and the user was the idiot.
In Europe the safety concern is electrocution with those scarry 220-240VAC mains. Here in the States, where currents are twice as high, fire in the building wiring is the main concern. Those wacky UK folks have loop mains (both ends of the wire go back to the fuse box) so they can have the high currents of US circuits with 240VAC. Yikes! That's why they put fuses in the plug ends of the power cords there.
As good as somthing sounds without mains protection, please think about what can happen if somthing goes wrong. Mabye you're a horible ugly bachelor, but how about the kids upstairs, etc.
Regards,
Mlise
I’d like to turn discussion to a preamp signal wiring scheme.
Most volume pots are not installed on PCB and wired a few inches away from the main gain stage assembly. The same usually applies to input/output connectors.
The RF wise, correct way to connect component (volume pot) is to run a coax and tightly twisted signal and return wires. This way the electro magnetic field created between them is minimized. Also, minimized are chances of picking up some external fields or coupling EMI.
Most audio preamps do not do it and run separate signal and return wires to volume pots, input/output connectors. Theoretical negatives of this are, increased wire inductance and separate signal and return wires act a small loop antenna picking up external fields.
Since all: volume pot, input selector switch, input/output connectors are wired this way, we have multiple antenna loops talking to each other within the same chassis.
Does it mean this wiring issue is not important to high fidelity audio designs?
Thanks
Sergey
Dayton OH
USA
Most volume pots are not installed on PCB and wired a few inches away from the main gain stage assembly. The same usually applies to input/output connectors.
The RF wise, correct way to connect component (volume pot) is to run a coax and tightly twisted signal and return wires. This way the electro magnetic field created between them is minimized. Also, minimized are chances of picking up some external fields or coupling EMI.
Most audio preamps do not do it and run separate signal and return wires to volume pots, input/output connectors. Theoretical negatives of this are, increased wire inductance and separate signal and return wires act a small loop antenna picking up external fields.
Since all: volume pot, input selector switch, input/output connectors are wired this way, we have multiple antenna loops talking to each other within the same chassis.
Does it mean this wiring issue is not important to high fidelity audio designs?
Thanks
Sergey
Dayton OH
USA
Bobken said:
The "paper" former is most likely Nomex However the voice coil wires are glued to the cone on their way to the flex lead out wires. That is where the fires start. There is usually a place where the two ends of the coil cross and they can short if the assembly wasn't done right after a few months or years of use. And while most high end speakers don't use paper, many of the other materials are combustible.
Fuse distortion: just for ducks, I just measured the distortion contribution of a 1/2 A picofuse soldered in series with 5 Ohms of Caddock resistors (to get a signal in range). The distortion increased from -147 dB 3rd HD to -136 dB 3rd HD w/ 700 mV drive. The resistor measures approx .25 Ohm. I have not tried other resistors and I don't trust clips to give a good enough connection. There is a clear thermal response to the fuse as well as I can watch its resistance decrease after stressing it
Fuses have resistance, inductance & capacitance
as any other passive component
so have some more or less effect on signals or DC current
now PCB rails and wires have the same
they are passive devices with resistance, inductance & capacitance
when we simulate our amplifiers
we use IDEAL components
and the PCB rails are not very counted for ( are they PMA Pavel Macura )
I sometimes even use a simulated power transformer for my simulations, with rectifier diodes + electolytic capacitors
this is important especiall if you feed you input stage from same supply as output
( unwanted feedback & ripple through the supply lines )
----------
Here I post such a siumlated transformer circuit using my Real Measured Values from one of my own power supply trafos i have here in my room.
Enjoy, young boys.
And consider how you use your Simulation softwares 😀
Get a little bit more real.
Like those avarage diyaudio people are.
I say destroyer X, DX-Amp, is for real .. more real even than Lineup!
as any other passive component
so have some more or less effect on signals or DC current
now PCB rails and wires have the same
they are passive devices with resistance, inductance & capacitance
when we simulate our amplifiers
we use IDEAL components
and the PCB rails are not very counted for ( are they PMA Pavel Macura )
I sometimes even use a simulated power transformer for my simulations, with rectifier diodes + electolytic capacitors
this is important especiall if you feed you input stage from same supply as output
( unwanted feedback & ripple through the supply lines )
----------
Here I post such a siumlated transformer circuit using my Real Measured Values from one of my own power supply trafos i have here in my room.
Enjoy, young boys.
And consider how you use your Simulation softwares 😀
Get a little bit more real.
Like those avarage diyaudio people are.
I say destroyer X, DX-Amp, is for real .. more real even than Lineup!
Attachments
Maybe a better choice of words?lineup said:
😀No insult intended, possibly a non native English speaker.
Sergey -
on the contrary: wiring issues are VERY important!
Not only how one does the wiring but also what types of wires and what material (and how that material is manufactured) is of utmost importance.
But if one needs a coax cable or not can be debated. I do not use coax cables in line level equipment. I use twisted pairs in those audio equipment.
In RIAA amps I do use coax cables.
Not only signal carrying wires are important but of course all wiring in an amp is important. Be it power supply cables, AC mains wiring, or supporting circuitry wiring.
How wiring is done is also important regarding safety isssues. I keep the AC mains wiring separate from all other wiring and use double wrapping for AC mains wiring and also for other high voltage wires.
Ground wiring scheme affects sonics (and hum and noise levels) so utmost care has to be taken regarding GND schemes.
So, wiring issues are a main concern in an amp.
What the best scheme is and what cables ot use and why, seems to be an ever lasting debate.
I tend to use 0,5 mm diam solid silver core wires in unbleached cotton for the signal paths, and for the rest I use many other types of wire. Still trying to find the best types.....
Sigurd
on the contrary: wiring issues are VERY important!
Not only how one does the wiring but also what types of wires and what material (and how that material is manufactured) is of utmost importance.
But if one needs a coax cable or not can be debated. I do not use coax cables in line level equipment. I use twisted pairs in those audio equipment.
In RIAA amps I do use coax cables.
Not only signal carrying wires are important but of course all wiring in an amp is important. Be it power supply cables, AC mains wiring, or supporting circuitry wiring.
How wiring is done is also important regarding safety isssues. I keep the AC mains wiring separate from all other wiring and use double wrapping for AC mains wiring and also for other high voltage wires.
Ground wiring scheme affects sonics (and hum and noise levels) so utmost care has to be taken regarding GND schemes.
So, wiring issues are a main concern in an amp.
What the best scheme is and what cables ot use and why, seems to be an ever lasting debate.
I tend to use 0,5 mm diam solid silver core wires in unbleached cotton for the signal paths, and for the rest I use many other types of wire. Still trying to find the best types.....
Sigurd
gurevise said:
Sigurd Ruschkow said:
this is, at least among beginners, the most common mistake
they get hum and mystical behavior in their amplifiers
and so they post and ask
For DC-Currents this is most often no problem in amplfiers
But for AC currents it means EVERYTHIIIINGG.
if your ZERO Reference = GROUND, is not clean ZERO
It will corrupt the whole AC performance of your amplifier.
See how important this is:
To have a correct grounding scheme
Sigurd.
🙂 have a look at basic layout I did for my 'new audio site'
notice one category and notice where I put it .......
Top Priority, man 😎
http://lineupaudio.freehostia.com/
lineup said:
I also thought it will have no effect until I've tried high quality fuses, all of them in the power supplies. Perhaps you can try it too.
Andre Visser said:
Do your self a favour.
And make a simple ABX Blind Test, with some friends.
When you still notice the 'fuse sound' come back and tell me again.
Or keep it strictly secret from me.
See my post above about a ABX Comparator of recorded sound files.
Make it myfuse.wav 16 bit CD quality .. just for validity sake 😉
Lineup
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