Sure! We need to look at the several fuses models available, each one with their specs.
And I would choose a fuse. with some extra margin, that will never blow if transistors don't short.
So, even with the amplifier severely clipping at the minimum speaker impedance (approaching square wave), the fuse would resist.
In addition, even if the output is shorted, fuses are not expected to blow. There must be a current limit (V-I limiter) and temperature protection to avoid the transistors to blow during a short in output.
I selected the fuses of the amp I shown for these conditions.
Clipped for hours, short circuit for hours etc. No fuse has blown during the extensive tests at that time.
And I would choose a fuse. with some extra margin, that will never blow if transistors don't short.
So, even with the amplifier severely clipping at the minimum speaker impedance (approaching square wave), the fuse would resist.
In addition, even if the output is shorted, fuses are not expected to blow. There must be a current limit (V-I limiter) and temperature protection to avoid the transistors to blow during a short in output.
I selected the fuses of the amp I shown for these conditions.
Clipped for hours, short circuit for hours etc. No fuse has blown during the extensive tests at that time.
Thank you so much Ron. I really appreciate you going through this so meticulously. What it tells me is thus: Fitting a correct size fuse is not going to affect the distortion in any way... But it shows so well that you should strive to keep power wiring and connections as low a resistance as possible (without going to extremes) if one doesn't want to lose the full power potential of the design. The drop is considerable. My use of 14AWG silver wire on these power connections seems to be justified. It would leave only the fuse resistance, and I have measured this at an average of just 0.01R0... Seeing is believing. Many thanks again Ron
Many thanks for your reply @anatech. All very sensible advice and facts. It really puts into perspective my thinking of what is going on in my amplifiers. I guess my style is the result of being a worrier. I do things in a way to thwart any chance of the things that I calculate (guess) actually happening. Knowing the reality is much better and very helpful. Much appreciate all what you have told me. Thanks again
Hi sonicles,
The silver wire has zero effect on anything, copper is more than fine. Silver is for switch and relay contacts, or jewellry.
Much of what you may read about on the internet is not written by people who actually know the truth. If you read a "white paper" by a manufacturer, or "our philosophy" section, that is pure advertising fluff. People always try to differentiate their products by any means possible. Others read this drivel and accept it as fact, then repeat it.
Then you have some things that make a miniscule difference under carefully controlled circumstances. Once you look at the entire system and environment, those tiny things are totally undetectable. At times they even bring negative aspects that do have an effect on the operating device.
What to do? Well, look at real life and design to minimise things you cannot reasonably eliminate as problems. I build, test and design real equipment and subsections every day. For audio, test and measurement and telecom. I have vastly improved performance of some very good commercial equipment, and not by using silver anything, or audiophile grade components. Just pure engineering backed up by empirical results.
There are some folks that are/were members who really pushed "magic wire and parts". Absolute nonsense even though one or more were famous. I won't point fingers, but time and truth eventually clear the air. Use common sense, everything obeys the laws of physics and factors at RF frequencies don't make as much of a difference at audio frequencies. Usually no difference unless you're talking about high frequency stability. Then we aren't talking about wire or a certain make of part.
The silver wire has zero effect on anything, copper is more than fine. Silver is for switch and relay contacts, or jewellry.
Much of what you may read about on the internet is not written by people who actually know the truth. If you read a "white paper" by a manufacturer, or "our philosophy" section, that is pure advertising fluff. People always try to differentiate their products by any means possible. Others read this drivel and accept it as fact, then repeat it.
Then you have some things that make a miniscule difference under carefully controlled circumstances. Once you look at the entire system and environment, those tiny things are totally undetectable. At times they even bring negative aspects that do have an effect on the operating device.
What to do? Well, look at real life and design to minimise things you cannot reasonably eliminate as problems. I build, test and design real equipment and subsections every day. For audio, test and measurement and telecom. I have vastly improved performance of some very good commercial equipment, and not by using silver anything, or audiophile grade components. Just pure engineering backed up by empirical results.
There are some folks that are/were members who really pushed "magic wire and parts". Absolute nonsense even though one or more were famous. I won't point fingers, but time and truth eventually clear the air. Use common sense, everything obeys the laws of physics and factors at RF frequencies don't make as much of a difference at audio frequencies. Usually no difference unless you're talking about high frequency stability. Then we aren't talking about wire or a certain make of part.
Hello anatech. Thanks for those thoughts.... I would say though, the reason I use silver plated wire nowadays is because, compared to the equivalent copper wire gauge, it offers lower resistance. Silver is 7% more conductive, DC wise. One other advantage is that it so much easier to solder. I use a silver doped LMP type solder and connection to spades and terminals is so much more reliable and faster. The price is not that expensive either. I'm a believer of little things adding together.... just to get the edge compared to basic construction. It makes me feel better/prouder about the end product if nothing else 🙂
Hi,
Let's consider the regular cable specs - reference Pirelli cables for residential installations.
14AWG is equivalent to 2.5mm2.
For 2.5mm2 cables, we see that the maximum AC current, when installed as 3 conductors together and inside a electrical pipe (worst case), is around 17.5A for ambient temperature of 30C (86F) and cable temperature 70C (158F).
Using a derating factor for ambient temperature to be 50C (122F), more typical for a inside temp equipment, we have a factor of 0.71 which reduces the maximum current to 0.71*17.5 = 12.4A
2.5mm2 cable AC (60Hz) resistance per meter = 0.0088.
Considering that connections within the cabinet will be maximum 30cm, we have 0.3*0.0088 = 0.0026ohms per cable.
For a 400W power amplifier @ 4ohms, we have output current = SQRT(400/4) = 10A RMS
Any other connection will drain less than that, since it will be half wave.
Skin effect at 20kHz and 14AWG will only marginally increase resistance and this can be decoupled by using capacitors right on the amp PCB.
Just buy cheap regular cables on your neighborhood electrical store.
Let's consider the regular cable specs - reference Pirelli cables for residential installations.
14AWG is equivalent to 2.5mm2.
For 2.5mm2 cables, we see that the maximum AC current, when installed as 3 conductors together and inside a electrical pipe (worst case), is around 17.5A for ambient temperature of 30C (86F) and cable temperature 70C (158F).
Using a derating factor for ambient temperature to be 50C (122F), more typical for a inside temp equipment, we have a factor of 0.71 which reduces the maximum current to 0.71*17.5 = 12.4A
2.5mm2 cable AC (60Hz) resistance per meter = 0.0088.
Considering that connections within the cabinet will be maximum 30cm, we have 0.3*0.0088 = 0.0026ohms per cable.
For a 400W power amplifier @ 4ohms, we have output current = SQRT(400/4) = 10A RMS
Any other connection will drain less than that, since it will be half wave.
Skin effect at 20kHz and 14AWG will only marginally increase resistance and this can be decoupled by using capacitors right on the amp PCB.
Just buy cheap regular cables on your neighborhood electrical store.
Hi sonicles,
Okay, time to think.
What is the difference in resistance over the longest length? What is the impedance of that circuit? What is the impedance of the external leads? What is the impedance of the load? The bulk of the low frequency current is carried throughout the entire conductor. Extreme high frequencies above our hearing (oscillation maybe?) is carried on the skin. AKA: the skin effect. This is more important at radio frequencies.
If soldering copper is too difficult I guess silver plated wire solves a problem for you. If you are searching for a miniscule improvement in performance, you are not getting any. It may help you feel better, so that's cool. But be honest with yourself.
Okay, time to think.
What is the difference in resistance over the longest length? What is the impedance of that circuit? What is the impedance of the external leads? What is the impedance of the load? The bulk of the low frequency current is carried throughout the entire conductor. Extreme high frequencies above our hearing (oscillation maybe?) is carried on the skin. AKA: the skin effect. This is more important at radio frequencies.
If soldering copper is too difficult I guess silver plated wire solves a problem for you. If you are searching for a miniscule improvement in performance, you are not getting any. It may help you feel better, so that's cool. But be honest with yourself.
About skin effect, her's the calculation in order to not be just an opinion.
14AWG @20kHz 1m cable will have 0.00971ohms, so very close to what I've calculated from Pirelli cable 0.0088ohms.
https://chemandy.com/calculators/round-wire-ac-resistance-calculator.htm
14AWG @20kHz 1m cable will have 0.00971ohms, so very close to what I've calculated from Pirelli cable 0.0088ohms.
https://chemandy.com/calculators/round-wire-ac-resistance-calculator.htm
Ok! I retired last year, so I'm plenty of time now to play with things I like such as this subject.
I've worked, based in Brazil, 13 years for canadians, Nortel, until its end in 2010 - good times there!
I've worked, based in Brazil, 13 years for canadians, Nortel, until its end in 2010 - good times there!
Add to the list: polished Silver plating is great at frequencies near a gigahertz.
The conductivity difference only applies to wires that have the exact same cross-section area and length.
So a 92 inch Copper wire has better conductivity than a 100 inch Silver wire of the same cross-section area.
Hi Speedskater,
Yup. That's why I often say that things that make a difference at RF frequencies don't have any real effect at audio frequencies.
Near a Gigahertz even the dielectric properties of PCBs and any other insulation matters. More so as the frequencies increase.
Yup. That's why I often say that things that make a difference at RF frequencies don't have any real effect at audio frequencies.
Near a Gigahertz even the dielectric properties of PCBs and any other insulation matters. More so as the frequencies increase.
I can solder as well as the best solderer. It's just that soldering silver wire with silver doped solder visibly runs better. It seems you need to attack and belittle people to make your point. It might say more about yourself than you realise..... it is obvious you need to put people down to make yourself feel better. Rise above this, just feel good about yourself regardless of others.🙂
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If you had ever tried to do the numbers, you must have recognized that your point was moot.
That is what Anatech tried to tell you.
Whether you like it or not.
That is what Anatech tried to tell you.
Whether you like it or not.
I was merely observing that silver wire has but one benefit from what you said. I wasn't trying to put you down, just illustrate what value silver wire actually has.
Back in October of 1970, Dan Meyer, a pretty smart guy, published the original SWTPCo "Tiger" mono amp design. Though it had some quirks, it proved to be quite popular. I always wondered why he fused only the negative supply rail. It also had a primary fuse and a thermal cutout switch. The early amp had no other protection what-so-ever. I'm not sure what was supposed to happen after that single fuse blew and the article made no mention of the logic behind it.