Speaker Cable installed by Electrician

conax

The Ritz wrote:

The lack of that rancour has made this into an interesting discussion - post away.

Oh boy, Ive got the knives and forks out now.

I won't argue with your calculations about loss over cables or their electrical behaviour -

Somebody should

I guess the more general issue about the effect on the overall "sound" is more one of subjectivity. I know that when I upgraded the speaker wire in my own system I noticed a difference - there's no point in me getting into "wine tasting" language about it, the sound was simply clearer to me. Mind you, the "temporary - for two years ! - speaker wire I had for my rears wasn't great so maybe it's no surprise.

A change of cable nearly always makes a difference, whether good or bad, whether its solving a missmatch or creating one that solves a problem. what people do to solve a particular problem may cause a problem for others, at the end of the day as you say its a matter of subjectivity.

The issue of satellite speakers is particulrly interesting - with the Kefs going down to 70hz, there's very little overlap if the sub is set to cut off at 80hz.

This means that setting up the speakers can be quite tricky to make sure that the sub and the sats are well integrated. Room response and sub placement are also influencing factors, but that really has to be sorted out by the person in their own environment. I'm using MS Genies and I still have some work to do - I'd like to try room equalisation, but am rebuilding my system bit by bit at the moment so it'll have to wait until I can pick up the requisite equipment secondhand.
Ritz.

yep the satellites have a lot of work to do, I assume the 80hz you refer to is the crossover setting, I would be inclined to set this as high as I could.

The Ritz

Oh boy, Ive got the knives and forks out now

I can only assume that you were posting that while eating an extraordinarily early cooked breakfast....................

I assume the 80hz you refer to is the crossover setting, I would be inclined to set this as high as I could.

That's not always a solution - it depends on whether the response of the sub is useful above the normal crossover point for one. I'm a fan of subs being felt but not "heard" - it shouldn't be possible to locate a sub in a setup, you should just feel the sub-bass ini the air and the lower register should appear in the soundstage. Trying to get a sub to compensate for the satellites "unnaturally" for want of a better word is likely to lead to an unhappy mix.

Ritz

mossym

conax wrote:

yep the satellites have a lot of work to do, I assume the 80hz you refer to is the crossover setting, I would be inclined to set this as high as I could.

meahhh..not really...if the sub freq response fell away sharply above 80 and your other speakers were reasonably flat down to 70 setting it to anywhere above 80 is going to give you far from optimal response. it really depends on what your speakers and sub can do

i'm staying out of the cable debate this time...:D

conax

mossym wrote:

it really depends on what your speakers and sub can do

true, I havent heard them, so cant comment on personal experience, I would find it hard to imagine that at 70hz they would be able to transition smoothly from the sub and maintaine the dept in lower dialogue. small satellites often have this problem, they sometimes need a bit of help before they begin to stand out on their own.

Anybody have a response chart for these speakers?

bell wire for speakers....any takers?

ZENER

conax wrote:

Somebody should

Feel free to do the calculations yourself if you doubt mine.

ZEN

conax

this has died a death so......

ZENER wrote:

Feel free to do the calculations yourself if you doubt mine.

ZEN

ZENER wrote:

If you're familiar with IEEE regulations

Nope can’t say I’m familiar with IEEE regulations,

then you will be aware that a 1mm cable drops about 28mV per amp per meter.

I knew there was a relationship but never really bothered to look and see what it actually was, as it just as easy to work it out on the resistance of the total circuit.
But having said that I went and worked it out and came to more or less the same (.30mV per amp per meter actually the first time I did it I got .32mV) I would assume the IEEE have better actual copper resistance values than I could find.

Assuming a 10m 2-core speaker cable of this diameter then the total length of the conductor is 20m (10 to and 10 from the speaker) then this equates to .56V per amp carried.

With you so far

An amplifier delivering - say - 50 Watts RMS to a speaker may in fact deliver transients of up up to 10 Amps to the speaker.

OK so this is connected to a load, which is in series with the speaker cable, so the total resistance of the cable and the speaker is now .5 Ohms! and the voltage is 5 Volts.

This means a 1mm 2-core flex of 10 meters would drop .56 x 10 across the length of the conductor which is about 5.6 volts !!

So the conductor is dropping 5.6v and given the voltage above….. what is that percentage?

Considering the amplifier may have up to 35V at it's output terminal this accounts for almost 1/6 of the total voltage output from the amp being dropped across the resistance of the cable rather than where it should be - the speaker !

Ok fair enough, so we better assume this is in relation to your first amplifier ratings (cause if we don’t it even makes less sense) so we have 35V, and 50 watts, so now we have a total series resistance of 24.5 Ohms…… but wait we don’t cause this voltage drop is across the cable (QUOTE:being dropped across the resistance of the cable) let me see….35v – 5.6v drops to 29.4v suffice to say they have started adding plastic to copper at this stage.

Also remember we haven't even touched on the capacitance and inductance inherent in all cables which would have an audible effect on a cable.

Which has to be remembered where it does make a difference these are LOW impedance circuits 95% of the effort should be made towards reducing the resistance of the cable 5% worrying about capacitance and inductance.

Where you are 100% correct on the voltage drop in cables and is a very useful piece of information your figures would be akin to a mechanic saying don’t buy that car because its not good handling potholes, and then driving it into a 100 foot crater to prove the point.


If I have made any errors above I apologise in advance.

Slaphead07

I'd say the only error is in thinking that audio cables can be measured in such a way. The listener's ears are the only arbiter of what might work or not. I have absolutely no idea about the calculations you guys are discussing but I do have a passing interest in them. I can however tell you which cable will give you which type of sound in your system.

ZENER

conax wrote:

this has died a death so......

Let's drag it up again to stir it up ? OK let's !

Nope can’t say I’m familiar with IEEE regulations,

That was aimed at Xennon who seems to have disappeared

I would assume the IEEE have better actual copper resistance values than I could find.

The IEEE print an appendix in the back of the regulations listing cable CSAs and a figure - correct to 2 decimal places - of the resistance of these cables.

OK so this is connected to a load, which is in series with the speaker cable, so the total resistance of the cable and the speaker is now .5 Ohms! and the voltage is 5 Volts.

Ok I appreciate you're trying to understand what's going on here but trying to simplify or dumb down this topic isn't going to help you or anyone reading this thread. Audio amplification, transmission (through cables) and reproduction is more complex than comparing it to simple resistance, voltage and current. Speakers are inductive, capacitive and resistive all at the same time (as are the transmission lines or cables) and amplifiers have to drive these complex loads best they can. Those that drive it well are considered "good" amplifiers - those that don't aren't. You are applying simple calculations to a complex set of numbers above. You cannot simply say the load has 5V across it and is .5 ohms in value - the 10 amp transient may be 90 degrees out of phase with the voltage across the load so in fact the total power is zero !! VxI=W - 0v x 10a = 0w. This is itself over simplifying it but it's just to illustrate the concept of phase.

I suggest you read a little about AC electricity and how it behaves in different loads - resistive, capacitive and/or reactive. You will then be able to understand how these seemingly impossible power ratings are realised and how manufacturers can play with the numbers to make ridiculous claims on power output. Ever wondered how computer speakers can produce 200W PMPO and yet only consume 3 or 4 watts of power from the supply.

If I have made any errors above I apologise in advance.

No errors just slight misunderstandings of concepts.

ZEN

conax

go back up and look at your original statement 50 watts RMS make up your mind not rubbish. as for PMPO.....now I know your taking the piss.

your phase relationships, now I appreciate that you said you are over simplifying things but you are never ever going to get a 90deg phase difference in a speaker system this is back to driving a car into a crater, keep the story on the speaker cables and power outputs. 45-50deg maybe worst case (really worst case) normal would be around 20deg (at some frequencies) do you know that this still makes your original calculations incorrect!

I am back here reading this, still cant believe you mentioned PMPO

padi89

Slaphead07 wrote:

I can however tell you which cable will give you which type of sound in your system.

This is not to take the pi55, but a genuine observation, so please,no need to get defensive.I see a lot of talk on various audio forums in relation to the $1,000,000 cable challange.(link is not from an audio forum)
http://gizmodo.com/gadgets/calling-********/james-randi-offers-1-million-if-audiophiles-can-prove-7250-speaker-cables-are-better-305549.php
As of now,nobody from any cable manufacturer or magazine critic has put themselves forward to take the test.Numerous emails have been sent out but nobody seems up for it
Now in all fairness if you promote a product that works all these wonders surely you must back it up?
A reply without an insult would be nice.:D

ZENER

conax wrote:

go back up and look at your original statement 50 watts RMS make up your mind not rubbish. as for PMPO.....now I know your taking the piss.

:rolleyes: Did you actually read that sentence ? Maybe without the beer goggles ?

your phase relationships, now I appreciate that you said you are over simplifying things . . . .

Yes I did say that I was over simplifying things, didn't you understand that statement ? Why are you picking holes in it then ?

do you know that this still makes your original calculations incorrect!

How so ? Phase errors don't change the fact that the copper cable has a resistance that is constant and irrespective of current, voltage or frequency this resistance never changes. Apply any current you like to it the drop will still be the same proportion of the power output of the amplifier.

I am back here reading this, still cant believe you mentioned PMPO

You obviously need to read the sentence a 3rd time then, I was giving an example of how manufacturers quote figures that suit their own ends.
200 Watts PMPO emblazened on a box looks a lot better to a punter than 2 watts RMS ! PC speaker makers - especially those from Taiwan - use this term extensivley on their packaging. Have a look at some of their packaging here. - 500W PMPO !!!!

ZEN

conax

ZENER wrote:

:rolleyes: Did you actually read that sentence ? Maybe without the beer goggles ?

explain

ZENER wrote:

Yes I did say that I was over simplifying things, didn't you understand that statement ? Why are you picking holes in it then ?

because it has nothing to do with the speaker cable voltage drop and the wattage.....nothing with reference to your original posts it is a statement that does not change anything even without the 90deg or the 45 of 20deg diff it still does not change the fact, its like something you just threw in.
the phase relationships are mainly to do with amplifier design, thats something the designer has to work with to protect the amp, it does not concern the user in his/her choice of cable. regardless of the phase relationship the current with respect to the voltage is still high or low just at different times the relationships to the voltage drops on the speaker cable are just the same your statement is to do with voltage drop on the cable with reference to current, the voltage drops you orignally stated dont exist at the same time to produce the drops you are claiming no matter what way you work the phase angles.

How so ? Phase errors don't change the fact that the copper cable has a resistance that is constant and irrespective of current, voltage or frequency this resistance never changes. Apply any current you like to it the drop will still be the same proportion of the power output of the amplifier.

yes it will and nobody here is saying any different. but the voltage drops you are using for your calculations are referenced to a certain amount of current and wattage the current and voltage and wattage all work together.

You obviously need to read the sentence a 3rd time then, I was giving an example of how manufacturers quote figures that suit their own ends.
200 Watts PMPO emblazened on a box looks a lot better to a punter than 2 watts RMS ! PC speaker makers - especially those from Taiwan - use this term extensivley on their packaging. Have a look at some of their packaging here. - 500W PMPO !!!!

your right I didnt read it correctly, apologies....I cant stand the word PMPO with reference to audio, other formats use it correctly.
I once read that the best way to convert watts RMS to PMPO was to stop a person in the street at random and ask them to pick a number between 1 an 1000 divide that by your mothers age add any two digits from your phone number then divide the lot by the original RMS wattage if it looks good leave it, if not add 100:)

Anyway I have run out of steam on this....for anybody reading this just get a good quality speaker cable, the larger the better (within reason) use mains cable if you wish but to get the best from the system (deff over longer runs)dont use it, and even if it just so happened to work correctly it still does not look nice.


EDIT:
to stop this going on forever why dont you show us your formulae for calculating, showing where at 50watts RMS 10amps and 35v the drops are as you stated, dont forget speakers are connected.

Slaphead07

paid89 wrote:

Now in all fairness if you promote a product that works all these wonders surely you must back it up?
A reply without an insult would be nice.:D

I'm not promoting anything, I'm not selling anything and frankly I have no interest whatsoever in cable challenges. What I said was - and you even quoted me! "I can however tell you which cable will give you which type of sound in your system." which was nothing to do with expensive Vs cheap cables. Write to the manufactures if it bothers you that much.

padi89

Slaphead07 wrote:

I'm not promoting anything, I'm not selling anything and frankly I have no interest whatsoever in cable challenges. What I said was - and you even quoted me! "I can however tell you which cable will give you which type of sound in your system." which was nothing to do with expensive Vs cheap cables. Write to the manufactures if it bothers you that much.

When i said "you", i meant as in cable manufacturers or magazine reviewers,my mistake.The test is not just cheap V expensive,but was brought up when a company described their cable as "danceable".If a cable can really change sound then surely with the prices they charge they can pick out their own against a much inferior product or against the competition.No need for me to write to a company they already show their true colors by not accepting the offer on the table, not that they would answer anyway.Its much easier to ask someone like yourself that agrees with their claims,thats all.Thank you for your time.

ZENER

because it has nothing to do with the speaker cable voltage drop and the wattage.....nothing with reference to your original posts it is a statement that does not change anything even without the 90deg or the 45 of 20deg diff it still does not change the fact, its like something you just threw in.
the phase relationships are mainly to do with amplifier design, thats something the designer has to work with to protect the amp, it does not concern the user in his/her choice of cable. regardless of the phase relationship the current with respect to the voltage is still high or low just at different times the relationships to the voltage drops on the speaker cable are just the same your statement is to do with voltage drop on the cable with reference to current, the voltage drops you orignally stated dont exist at the same time to produce the drops you are claiming no matter what way you work the phase angles.

Care to repeat that with punctuation included ? It makes absolutely no sense whatsoever !!! Do you even understand it yourself I wonder.

yes it will and nobody here is saying any different. but the voltage drops you are using for your calculations are referenced to a certain amount of current and wattage the current and voltage and wattage all work together.

Again, some punctuation here wouldn't go amiss.

EDIT:
to stop this going on forever why dont you show us your formulae for calculating, showing where at 50watts RMS 10amps and 35v the drops are as you stated, dont forget speakers are connected.

Are you completely devoid of sense ? I used figures to illustrate how the cables resistance effects the amount of power being delivered to the speakers - the figures them selves are inconsequential - they are examples to put into ohms law to give volt drops as examples. It's the proportions that are the point here, can't you see that ? I mentioned phase angles to try to explain how larger currents appear to be delivered to speakers when you seemed to think their impedance dropped to 0.5 ohms for some strange reason and the voltage from the amp dropped to 5 volts !!! Audio signals are extremely dynamic in nature and an amplifiers job is to reproduce these signals as faithfully as possible - to do this it must be able to deliver the dynamics in power to suit.

I'll tell you what, as you seem at least to agree that a larger csa is more desirable why don't you explain why in your words with your language. That way at least I can try to figure out exactly what your points are.

ZEN

Slaphead07

padi89 wrote:

.Its much easier to ask someone like yourself that agrees with their claims,thats all.

Will you stop misrepresenting me. Not only have I never agreed with "their claims" I'm utterly unaware of who these companies are or what their claims might be. It doesn't interest me at all.

I try cables before I buy them and have never read any cable company's "blurb".

conax

ZENER wrote:

Are you completely devoid of sense ?

I must be after what I have been calculating for the past 3 hours

ZENER wrote:

I used figures to illustrate how the cables resistance effects the amount of power being delivered to the speakers

Yes you did, but you mixed IEEE fact and your fiction to prove a point that doesn’t exist in an audio system therefore invalidating your claims.

ZENER wrote:

the figures them selves are inconsequential

then why bother with them why not say smaller diameter cable = more resistance it is not as if this has not been mentioned many times in the past, if they were inconsequential why make them up, why not use real world figures to prove your point?

ZENER wrote:

they are examples to put into ohms law to give volt drops as examples.

yet when you use Ohms law, they are incorrect. And yet further on in your discussions you claim they exist outside of Ohms law and you have to include phase angles and impedance to appreciate them.

ZENER wrote:

It's the proportions that are the point here, can't you see that ?

Yes I can, cant you see that the proportions with respect to your original "figures" are totally incorrect, again why didn’t you use proportions that showed the real drop values, that would have served its purpose for any reader who wished to learn more about the subject, instead of confusing the subject with incorrect values.

ZENER wrote:

I mentioned phase angles to try to explain how larger currents appear to be delivered to speakers when you seemed to think their impedance dropped to 0.5 ohms for some strange reason and the voltage from the amp dropped to 5 volts

Because at that simplistic stage of the discussion, we were using Ohms law (even if it was only at a snapshot in time and not including impedance). The electrical properties at that time and space are correct; you yourself clearly mention Ohms law with reference to your calculations.
My figures above are using Ohms law, and if you even bothered to work it out using your original figures the total resistance at that stage would be .5 Ohms using Ohms Law.
And you have also conveniently omitted the fact that as the current rises the voltage drops even further pushing your calculations out.
(I have since spent time working the figures to include true power delivered with multiple frequencies (100Hz-1K as this is mainly where the current is and after that the response is more or less stable)into the load using typical values impedance/reactance/phase angle (cosine) standard power amplifier limitations and power supplies, I have also gone to the trouble of working the whole lot out at various phase angles.

ZENER wrote:

!!! Audio signals are extremely dynamic in nature and an amplifiers job is to reproduce these signals as faithfully as possible - to do this it must be able to deliver the dynamics in power to suit.

yes they are, if they were not you wouldn’t hear anything. So in dynamic I assume you are referring to the fast changing states and phase angles with reference to power supplied, absorbed and returned within the circuit. But all of these states still follow rules, the rules can’t be changed i.e. you just cant make them up to suit your needs.

ZENER wrote:

I'll tell you what, as you seem at least to agree that a larger csa is more desirable why don't you explain why in your words with your language. That way at least I can try to figure out exactly what your points are.

My points are very simple, the figures you quoted are incorrect. Those voltage drops across the conductors don’t exist in an audio system at the wattage,voltages and currents you suggest. There is little point in telling somebody “this is why you should increase the size of your cables” if the reason given is incorrect, even if the general outline is correct.

Then after suggestions were made,

CONAX wrote:

Somebody should

Maybe indicating that your figures and reasons were not correct, you added this.

ZENER wrote:

Feel free to do the calculations yourself if you doubt mine.

This would indicate that you in fact considered your calculations to be correct.

I also posted this, which was a hint to indicate that your figures were not correct with a little “something hidden in there as well”

CONAX wrote:

50Watts 10 meters of .75 copper cable into 8 Ohms dB loss .87dB, 1mm .45dB, 2.5mm .07dB

you replied with this.

ZENER wrote:

Sounds about right, the bigger the cable the lower the loss. Simple physics !

At this stage it would be obvious that the whole matter had in fact gone right over your head.



After that you changed over to Phase angles and quite correctly impedance/capacitance/reactance and so on. The phase angles in my opinion were a total bluff, as I mentioned and I will admit in proportion to importance (with reference to your original “figures” )at this level they would be more of a consideration for the design issues of the power amplifier itself, heat dispersion and power supply design, but they are of coarse important if you want to get down to the nitty gritty of calculating the true power levels and voltage/current loss on the transmission line (but not as much as you would think)
Now in my time I have built and blown the complete **** out of many an audio power amplifier using sustained low frequency to look at the power dissipation and limits(I used to build as a hobby) and in my opinion you can either take the route of over analyzing your design or you can use simple rules to cover and give some head room. I have always found that working with the simple rules works best overall.

Anyway as said earlier I worked out your original “figures” to include impedance/reactance and the associated phase angles and blah,blah,blah. And where as I would have probably liked to say at this stage I wasted my time I actually found the challenge enjoyable and learned a thing or two. But either way there was at no stage given your original “figures” the voltage drops across the transmission line as you originally suggested. In fact depending on the phase angles/frequencies and all the rest, values of between 200.725 Watts and obviously enough where there is no displacement i.e where the power factor is 1 (also better known as what works with Ohms law) 350Watts are required. Some of these calculations also included relationships that should not appear in a correctly operating audio system but either way I am happy that your original statement is pure and total rubbish, with exception to the IEEE regs.

Now without answering with any smart comments would you please show how you arrived at your original calculations? How did you apply your stated currents, voltages and wattage (irrespective of anything else use Ohms law if you must) to the voltage drops across the transmission lines. Do u think you can actually do that one small thing? And could you try doing that first without digging out and posting extracts from the above.
It is after all a very simple request and given your "can't you understand" attitude towards most of my comments, it should be easy for you to accomplish.

padi89

Slaphead07 wrote:

Will you stop misrepresenting me. Not only have I never agreed with "their claims" I'm utterly unaware of who these companies are or what their claims might be.

OK then, cable believer would have been more appropriate.

ZENER

conax wrote:

I must be after what I have been calculating for the past 3 hours

Ok then let's see these "calculations" then !!

All your post contains is veiled threats of proving me wrong yet you haven't given one tiny shred of proof to back up these threats. So come on then let's see the calculations and quit spouting BS.

I look forward to reading your next post, no really . . . I do:rolleyes:

ZEN

conax

Right let’s put this way so you might understand it. Your figures have no bearing on the reason to upgrade the size of the cable.
They are transients that in real world audio are only of concern to the designers and bear no relationship why one should upgrade their cable.
For your drops to have any meaning with regards to upgrading the cable, the amplifier would have to be supplying in the order of 300 watts.
I again say that you are picking the extreme's to prove a point. What work do you really expect these transients to be doing, how often and where.

The important factor governing the size of the cable is its resistance, whether or not the resistance is correct or not for the application is governed by calculating the losses and applying the ratios to see if the losses are acceptable. The acceptability of these losses are applied to real world operational voltages, currents and wattage's that present themselves in a real world audio amplifier. For the 50Watt RMS you originally posted this would be only a few amps if everybody were to apply the terms you state, as a reason to upgrade the size of cables the whole audio and electrical world would be in turmoil.
The resistance value of your stated lengths for 1mm cable are only around .437937619 ohms (or in the real world .44 Ohms) with pure copper (speaker cable would be close OFC a bit closer but those extra digits are outside the resolution of usable dB).without exception the rest of the audio/electrical world would use ohm ratings like this to calculate the dB loss as applied to the standard operational values of the amplifier to coincide with what is acceptable or not.

You appear to be unique in the fact that for some unknown reason want to change this, you appear to want to apply extremes because I can only assume that when you did a log ratio (assuming you can even do a ratio) on your only real useful piece of information 28mV drop per amp per meter they did not look good enough so you found some information on operational extremes somewhere and decided it looked a lot better with this.

Now I don't expect any validating answer from you at this stage, so I would like to invite anybody else reading this to offer their opinion, I would especially like to hear a response from the mods, it would be nice to at least hear their expertise to dismiss inaccuracies on both sides of this discussion. Forums are great but if you have two clowns like me and zener flaring away like this it really serves no purpose at all.

And zener there are no threats in any of my points.

ZENER

At last something coherent to work with, ok then lets see if we can't put this one to bed once and for all !

The original poster asked if the 0.75sq cables an electrician installed were adequate for his sound setup. Xennon replied that in his opinion they were fine for up to 600w, which in electrical terms is correct. For supplying power to a lamp or appliance up to a few amps its ok as the appliance isn't going to complain of a few lost volts.

However when we speak of audio signals every volt is precious, and every ohm of resistance in the cable feeding a speaker dissipates precious detail containing power. Therefore it's desirable to minimise these losses as much as possible. I think up to this point we agree.

At this point I gave the resistance of a 1mmsq cable of length 20mts as an example which has a characteristic resistance of 28mV per Amp per meter which equates to .028 ohms per meter which gives this cable a total resistance 0.028 x 20 = 0.56 ohms. Compared to a typical 8 ohm load that represents 14.286 % of the load of the speaker. Not an insignificant amount I suggest. Now follow me here if you can, the resistance of the cable DOES NOT CHANGE because the voltage or current changes so it does not matter what current you put through it. The resistance stays the same, therefore the proportion of the total power delivered by the amp lost in the cable remains the same - 14.286%.

In a system where the amplifier delivers 20VAC (typical of a 50W amplifier) RMS to a speaker of 8 ohms and a cable similar to that above we get:

I=V/R = 20/(8 + 0.56) = 2.336 Amps

The power dissipated in the speaker and the cables are:

P=I^2xR = 2.336^2 x 0.56 = 3.056 watts = power dissipated in cable

2.336^2 x 8 = 43.655 watts = power dissipated in speaker

Therefore the total power in the circuit = 3.056 + 43.655 = 47.711 watts

therefore the cable loss in dBs would be:

XdB = 10log(Ws/W) = 10log (43.655/47.711) = 10log 0.915 = -0.385dB

This loss is constant and is present regardless of current or voltage because the ratio will always be the same as long as the speakers impedance remains at 8 ohms. Which seems to be an alien concept to you :

conax wrote:

You appear to be unique in the fact that for some unknown reason want to change this, you appear to want to apply extremes because I can only assume that when you did a log ratio (assuming you can even do a ratio) on your only real useful piece of information 28mV drop per amp per meter they did not look good enough so you found some information on operational extremes somewhere and decided it looked a lot better with this.

All the calculations above assume the speakers impedance remains constant across the frequency range which of course it won't. At resonance the impedance will peak nearer to 40 ohms depending on the actual speaker and drop to as low as 4 or 5 ohms at some parts of the spectrum either side of resonance. At this 5 ohm region the current in the circuit increases to about 3.6 amps at which stage the cable loss increases to -0.461 dB. All this means is that the losses in the cable are not constant across the frequency spectrum which leads to a compression type effect - as the power increases the cable loss increases meaning less total power to the speaker and vise versa and this effect is frequency dependent which is not something you want in a hi-fidelity audio system.

Power ratings of hi-fi amps are given for THD levels < .1% typically and into a stated impedance usually (but not always) 8 ohms, the amplifier can deliver higher power with increased distortion into this load or lesser loads meaning higher currents. For our test amplifier above the peak current it delivers into 5 ohms (lowest speaker impedance above) = Vp/5.56 (including cable resistance) = 5.09 amps. Which in P-P terms is over 10 amps. These figures are without driving the amp into distortion and could easily be achieved for example by playing the canons in Master & Commander at decent volume level like they would be played in chez ZENER

Another consideration is that many AV amps deliver 70watts or more per channel - mine, a Denon, delivers 90 watts per channel. I recently installed a Pioneer which delivers 130 watts per channel - the electrician wiring the extension where the amp was to live nearly fell off his ladder when I told him the alarm wire he'd run in would have to be increased to a 2 x 2.5sq flex. Still not ideal but at least it gave the system some chance of shining. Connecting a system like this to the aforementioned 0.75mm cables would mean even higher losses in the cable and degraded sound quality which I think we can agree on. Can you imagine what it would have been like with the alarm wire ?

So in conclusion I propose a larger CSA is more desirable when connecting speakers of any kind but even more desirable when the desired outcome is hi-fidelity reproduction.

ZEN

mossym

zener, in a toally innocent way, out of curiosity more than anything, if you're an electrician for 23 years why on earth was someone else wiring your house for you?

sorry for the off topic question!!

conax

mossym wrote:

zener, in a toally innocent way, out of curiosity more than anything, if you're an electrician for 23 years why on earth was someone else wiring your house for you?

sorry for the off topic question!!

I was wondering the same.

Zener

A well thought out and coherent answer even with its mistakes in calculations I am impressed. I would like to add that at no stage did I indicate that the resistance of the cable changed and also to add that where you had done a good enough job representing power loss (errors excluded) it bears no resemblance to your original figures.

ZENER

conax wrote:

A well thought out and coherent answer even with its mistakes in calculations I am impressed. I would like to add that at no stage did I indicate that the resistance of the cable changed and also to add that where you had done a good enough job representing power loss (errors excluded) it bears no resemblance to your original figures.

Do you know you haven't at any stage presented an alternative to anything I've presented above. Also please point out the "mistakes" you see in my reply. I'm betting you can't because you haven't a clue what your talking about and to be honest I don't know why I've wasted my time entertaining you at all.

Now if you wish to retain ANY credibility here POST YOUR CALCULATIONS or I'll just consider you a mere troll and stop feeding you.

Also, where did I say someone wired MY house ? I install AV equipment for clients and in this case the client was building an extension for use as an AV room. If you carefully read my post you'll see this. An act of desperation from someone clutching at straws IMO.

Let me also assure that you (conax) did suggest that I'd chosen values to make the claims "look better", this suggested to me at least that you think by changing the current values the losses changed !!

So far I'm the only one here to present a valid and illustrated view of my argument whereas all you can do is quote me (incorrectly and out of context for the most part) and type some big words including excerpts from a website or two and some technical sounding terms.

Now - PUT UP OR SHUT UP !!!

ZEN

mossym

ZENER wrote:

Also, where did I say someone wired MY house ? I install AV equipment for clients and in this case the client was building an extension for use as an AV room. If you carefully read my post you'll see this. An act of desperation from someone clutching at straws IMO.

was just curious as to why you hadn't done the wiring yourself...no insult meant...

conax

Yawn.

Vs =20V
R1=.56R (cable)
R2=8R (speaker)
Rz= R1+R2 = 8R56

Load Current (IRz) => I=V/Rz
20/8.56 = 2.34A
Watts Total (load Rz) = VxI
20x2.34 = 46.8 watts

Voltage R1=?
Voltage R2=?
IR1=2.34A
IR2=2.34A
Watts R1=?
Watts R2=?

Voltage R1 (cable)
R1 (target)/ Rz x Vs = Voltage R1
.56/8.56x20= 1.3v
Voltage R1= 1.3v

IR1 = V/R1 => 1.3/.56 = 2.34A
Watts R1 = VxI => 1.3 x 2.34 = 3.04 Watts

Voltage R2 (speaker)
R2/Rz x Vs = voltage R2
8/8.56 x20 =18.7v
Voltage R2 = 18.7

IR2=2.34A
Watts R2 = VxI => 18.7 x 2.34 = 43.76 Watts

VR1 + VR2 = Vs 18.7 + 1.3 = 20v
WR1 + WR2 = Watts Total = 43.76+3.04 = 46.8 Watts

Therefore:

Vs =20v
Voltage drop cable = 1.3v
Watts cable = 3.04
Voltage speaker 18.7
Watts speaker 43.76

20log wattage ie power ratio = -.29dB (cable)

as well at that there are other errors in your calculations well maybe not your calculations, but your statements but I couldn’t be bothered.

I al least thought by the time I posted this you would have spotted your mistake.......but I should have know better.

Xennon

couple of points you need to consider;

You are dealing with impedance not resistance, i.e. frequency dependent resistance.

The characteristic impedance of a speaker varies considerably across the spectrum.

An 8 Ohm speaker rarely measures 8 Ohms at 0 Hz, more like 6 Ohms.

conax

Xennon wrote:

couple of points you need to consider;

You are dealing with impedance not resistance, i.e. frequency dependent resistance.

The characteristic impedance of a speaker varies considerably across the spectrum.

An 8 Ohm speaker rarely measures 8 Ohms at 0 Hz, more like 6 Ohms.

well aware of that, and the ohms you measure a 0Hz is the DC resistance of the coil and bits. however long ago here the ohmic way was put up for the basic calculation. it does vary, there is a huge hump down therein the low freq and not to mention the other complications in measuring a real life installation (but hang on we may have to go there yet) but as said this is just a simple format more to do with the cable, remember that the cable only exhibits its changes due to the amplifier and connected speaker working through it.

Xennon

Amplifiers are transient devices delivering varying voltages in or out of phase with each other so a 500 W amplifier may deliver up to 30 or 40 amps to a speaker - so a 1.5mm cable ?? I think not.

If this is what 1st year sparks are being thought then someone needs to re-evaluate the content of that module. A 500W amplifier cannot deliver 30 or 40 amps.... ever...well....unless you throw it into a 3x100A board.

Or has the Hi-Fi world really beaten the conservation of energy rule?...

Slaphead07

Xennon wrote:

Or has the Hi-Fi world really beaten the conservation of energy rule?...

the HiFi world is not interested in calculations, rules or laws... we rely only on our ears. The guys are discussing physics, not hifi.

conax

Slaphead07 wrote:

the HiFi world is not interested in calculations, rules or laws... we rely only on our ears.

Believe it or not Slaphead that is the way I look at it as well, I normally judge a system on its performance, but having said that I would also look at its specifications to determine what is best to connect to it, or look at its specifications to see if it can deliver what I require. Specifications are based on physics.

ZENER

conax wrote:

Yawn.

Perhaps instead of yawning you should have realised this . . .

20log wattage ie power ratio = -.29dB (cable)

20log is used for voltage, current or amplitude - power is calculated as 10log. The rest of your calculations are out by one decimal place. I used 3 you used 2 - laziness - no just an attempt to score the last points by having your numbers differ to mine.

Your post just confirms my initial belief - you're a bulsh1t artist and a troll - and exceptionally qualified at both it has to be said !!

conax wrote:

as well at that there are other errors in your calculations well maybe not your calculations, but your statements but I couldn’t be bothered.

I would expect nothing less of a troll, goodbye.

@ Mossym: My ire wasn't aimed at you, my apologies.

@ Xennon: When I was an apprentice audio installations weren't on the syllabus - has this changed ? A 500 watt amp into 4 ohm would supply 11A RMS which is 15.8A peak or 31.6 amps p-p, this is while being fed with a constant signal, with true life dynamic input the currents mentioned could easily be reached. Your comments are accurate for electrical installation situations where a volt drop is acceptable. In the context of the discussion here these losses are simply not low enough.

ZEN

conax

ZENER wrote:

20log is used for voltage, current or amplitude - power is calculated as 10log. The rest of your calculations are out by one decimal place. I used 3 you used 2 - laziness - no just an attempt to score the last points by having your numbers differ to mine.

I swear Its like shooting fish in a barrel, you are soooo predictable, I left that there just for you, and if you had noticed further it was the only calculation that I didn’t show fully, and finally just to show one part of your pure ignorance it is worked out using 10 log you prat.

ZENER wrote:

The rest of your calculations are out by one decimal place. I used 3 you used 2 - laziness - no just an attempt to score the last points by having your numbers differ to mine.

You are without a shadow of doubt the most ignorant and abusive person I have ever come across. You appear to be under the impression that because you say something it is right and that is that. I said that you did a good enough job doing the original calculations (errors and all) I hinted without picking it out abusing you with it, I hinted again there was an error, and you come back with the crap about decimal places………what is wrong with you, seriously what kind of mentality is present in a person who starts to rant and be abusive like that.

Here!!!!!!!!

20v x 2.336A = 46.72 watts not 47.711


I used 2 decimal places to allow for reversing the calculations back to the original values, this is common practice and best practice. You show me a text book anywhere that works to 3 decimal places where the answers don’t work back to the questions or are they all just lazy as well.

If you look at your 3 decimal place calculations they don’t reverse back to the original e.g. 3.056 + 43.655 = 46.711 even though the above shows 46.72 this not a problem here (and this is not to show you up so don’t go on about it saying it’s a tiny amount does not make a difference blah, blah) this is just me saying in calculations like these it is just best practice. In larger calculations where there is a cascading production when working back to confirm a later calculation it is very useful to confirm any mistakes or correct values, not to mention when working out biasing at a later stage in design (well on paper anyway)

Xennon

A 500 watt amp into 4 ohm would supply 11A RMS which is 15.8A peak or 31.6 amps p-p,

yes but the maximum current from the amp at any stage on a sine wave output is 15.8A, never anywhere near 31A. The damping factor of the amplifier wouldnt allow transients to create overrated output swings the amp would clip the output waveform.

The Ritz

Zener, conax

(In no particular order of merit)

Lads, would ye ever give it a rest ? This was an interesting discourse until it descended into trolling, with the inevitable resultant abuse. Please spare me any excuses.


I already showed a yellow card on this thread and have yet to hand out a ban to anyone on Boards. Tempted to change that state of affairs......

Padi89

OK then, cable believer would have been more appropriate.

This hasn't gone un-noticed............



Ritz.

conax

You are of coarse right, apologies all.

ZENER

Apologies Ritz, it's a very emotive topic. Apologies to the other posters here too, a ridiculous situation and it got out of hand, sorry for that.

Conax, I'm not going to continue with this, I made a simple calculation error in my post - no big deal under normal circumstances but it fed the point scoring mentality the thread descended into. Aside from that error our calculations were within a stones throw of each other. We're obviously of a similar background/profession so it's pointless really continuing in this direction. I stand by my posts - apart from the errors of course - because they were based on experience and not simply text books alone.

Xennon, I accept your point about the 500W amplifier but if you read the earlier posts and look at the impedance graphs of a typical 4 ohm speaker you will see that the value varies with frequency from 2 ohm up to 40 or 50 ohm at resonance. It's obvious then that the current output could peak at 30 amps.

The damping factor of the amplifier is it's ability to provide a circuit for the currents generated by the coil of the speaker to dissipate into and to stop the cone from resonating, after all it is a coil within a magnetic field so any movement will generate an emf. A good quality amplifier will have a very low source impedance of less than ~0.5 ohm to present to the voice coil which will quickly absorb the generated current. Of course between the voice coil and the amplifiers source impedance is the resistance of the cable so if the amp has a source of say 0.5 ohm and the cable is also 0.5 then the damping factor will be effected - assuming a 4 ohm speaker:

Damping Factor= Zload/Zsource = 4/0.5+0.5 = 4

Get rid of the cable resistance of 0.5 ohm and the factor becomes 8 so obviously the lower the resistance of the cable the higher the damping factor.

ZEN

The Ritz

Zener, conax,

OK lads, thanks........... business as usual.


Ritz.

padi89

The Ritz wrote: »

Padi89



This hasn't gone un-noticed............



Ritz.

Are you serious? I reworded to be more accurate but your reading it as a smart arse comment. It was not meant to be or shouldn't be taken as a dig unless the person has their own doubts on what the believe they hear.Cannot see your point to be honest.

Slaphead07

padi89 wrote: »

It was not meant to be or shouldn't be taken as a dig unless the person has their own doubts on what the believe they hear.

I suppose that wasn't a childish dig either?

padi89

Slaphead07 wrote: »

I suppose that wasn't a childish dig either?

Not at all and to be honest i do not see where you are coming from.I presumed you had no problem with my post Slaphead, i cannot see how things have changed.Childish?,give me a break.

conax

ZENER wrote:

Damping Factor= Zload/Zsource = 4/0.5+0.5 = 4

Get rid of the cable resistance of 0.5 ohm and the factor becomes 8 so obviously the lower the resistance of the cable the higher the damping factor.

ZEN

Just for anybody who is interested,
Like the saying goes " what goes up....must come down" with formulae what goes forward "generally":) goes backwards. so if you have an amplifiers stated damping factor with reference to a load it can be rearranged to do the following:

we have DF=Zl/Zs so to find Zs that we can reaarange the formule to find the source impedance of the amp, by doing this Zs=Zl/ DF "as stated to a Zl which should be the same Zl connected to the amp"
This is more like the poor mans work bench way of doing things....but all the same.

The Ritz

padi89,

your reading it as a smart arse comment

..Yip, the topic of cables seems doomed on this forum. I find it difficult to read your comments as anything other than baiting, hence my comment.

Someone says they make no claims for manufacturers

i.e.

Will you stop misrepresenting me. Not only have I never agreed with "their claims" I'm utterly unaware of who these companies are or what their claims might be.

and you respond with

OK then, cable believer would have been more appropriate

..... as far as I'm concerned that's baiting, a bait that Slaphead07 did not rise to. Your protests just make it more obvious, as far as I'm concerned. I have a pain reading threads descend into smart remarks on the subject of cables, and don't intend to discuss this any further.

Ritz.

SidinNaas

You folks ever planning to meet up for a beer ?

If so let me know as I'd be interested in coming along for the entertainment.

Not too good on the electrical calculations (although doubt that many jobbing electricians are either) but OK on maths and physics. Have ears so probably more than qualified to join in.

Slaphead07

The Ritz wrote: »

I have a pain reading threads descend into smart remarks on the subject of cables, and don't intend to discuss this any further.

Ritz.

Unfortunately Ritz once you go past entry-level HiFi then cables become as important as any other component in a system. It would be a pity if we couldn't discuss real hifi on a hifi forum simply because some posters haven't heard a difference between cables or, in some cases, have never heard proper cables at all.
Essentially these forums are being kept at a low level by a few posters... I know other HiFi geeks think I'm insane even posting here but if I can point some people toward good quality gear then I'm happy to do that, but I don't intend to take abuse everytime I suggest a low-cost tweak to somebody who's invested in decent equipment.

Maybe there's room for a separate genuine high-end HiFi forum?

The Ritz

Slaphead07,

I don't disagree that the further up the foodchain you go with hifi, the more critical each component becomes, as well as the match between components. I think you would agree that the incremental difference often becomes smaller, and not necessarily in proportion to the increment in price. As you've pointed out yourself, the difference in effect is down to what the listener hears and is willing to pay for. My own experience with high-end hifi is very limited, I'm more interested in the home cinma stuff, but in my experience there are very few (if any) limitations or absolutes when one is dealing with what your own eyes and ears tell you.

I accept that there are the sceptics who point to their understanding of the science and physics, and treat a lot of the esoteria (if such a word exists...) associated with the upper reaches of hifi as mumbo jumbo, and consider the purchasers to be gullible, at best. What I don't accept is the impulse to rubbish other peoples' opinions and posting which is clearly constructed to insult.

While it can be frustrating (and I've seen it often enough at this stage) to try to explain ones position in the face of sometimes uninformed incredulity, the now almost predictable resultant descent serves no purpose whatsoever.

Essentially these forums are being kept at a low level by a few posters

I'm not sure I'm comfortable with that idea. I think that newcomers in particular deserve to be treated with respect and given decent advice, appropriate to the question they ask. What appears to happen from time to time is that people see an opportunity to start a slagging match because they disagree with some statement, and that kind of carry-on just makes the place unpleasant and generates an unwelcoming tone for people who want to ask questions, discuss and learn something new. That kind of stuff isn't helpful for the development of the forum or generating a shared interest, so I agree with your comment above insofar as some posting goes. I would be less happy in "targetting" anyone, I'd rather people would get the message that they should lighten up and be more tolerant of the diversity of view points.

I respect the presence of all posters here, particularly those regularly answer questions, those who share their knowledge and experience and those who are prepared to discuss their ideas in detail, but my patience is running thin with some of the reactions to commonplace hifi advice.

If people feel the need to vent their spleen and be insulting, they should go to the Thunderdrome.................. if you just disagree with something here, say so, give your reasons and leave it at that. If you can't discuss something rationally without resorting to insults, then think twice before posting.

I appreciate that this reply to you comes fairly quickly after coments I made to Zener and conax on this thread.............. Lads, if your reading this don't make the mistake of thinking that there are any veiled (or otherwise) threats or references to ye or anyone else in particular in my remarks.

As for the suggestion for a "true" hifi forum, that's one for Admins - it usually needs a fairly decent level of demand, but it does no harm to ask.


Ritz

Slaphead07

The Ritz wrote: »

As for the suggestion for a "true" hifi forum, that's one for Admins - it usually needs a fairly decent level of demand, but it does no harm to ask.


Ritz

More "thinking out loud" than a suggestion. I doubt if there's enough demand on a broad forum such as boards.ie but obviously that's where my own interests lay. It would be good all 'round if there was though, I know quite a few guys who would contribute if there was a forum with less Argos and more Arcam.

The Ritz

if there was a forum with less Argos and more Arcam.

.... Lol........ Everyone starts somewhere............... there's always the opportunity (which you've regularly taken yourself) to direct people towards decent entry level kit instead of all-in-one stuff....

BTW, I edited my post above.............
Ritz.

conax

Now the first thing I am going to say here is that this is just a bit of audio humour, it is not meant to offend anybody.

I think that if the admin do decide to start a dedicated true HiFi forum maybe ye could call it the “It just does” HiFi forum, this of course would be with reference to every answer on every question.:D

As for you Slaphead07 I would miss the things you say if you moved. And I will tell you, recently I suggested your “squash ball solution” to a person who is an avid consumer in the upper echelons of the HiFi arena, and he thought it was a particularly good idea……I didn’t comment either way. ( I would like to add that this same guy put isolators under the power supplies to his amp….I feel it prudent not to add the reason why though:rolleyes:)

ZENER

conax wrote: »

Now the first thing I am going to say here is that this is just a bit of audio humour, it is not meant to offend anybody.

I think that if the admin do decide to start a dedicated true HiFi forum maybe ye could call it the “It just does” HiFi forum, this of course would be with reference to every answer on every question.:D

I think we already have a forum for that sort of thing . . . it's the religion thread

. . . recently I suggested your “squash ball solution” to a person who is an avid consumer in the upper echelons of the HiFi arena, and he thought it was a particularly good idea……I didn’t comment either way. ( I would like to add that this same guy put isolators under the power supplies to his amp….I feel it prudent not to add the reason why though:rolleyes:)

Are the reasons too ridiculous or are you not a covert to "It Just Does" yourself yet ?:D

I posted in that thread that I could understand why certain items would benefit from isolation - power supplies would be one of those items imo. Big trafos vibrating transferring those vibrations via microphony (sp?) to other sensitive devices. MM or MC phono input stages would be particularly at risk.

ZEN