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Why pick on cables ? - Page 22  

post #316 of 403
Quote:
Originally Posted by Strangelove424 View Post

Funny you mention it, I recently purchased a current meter to measure electricity usage on my computer at idle/load, and I tested my receiver with it. The receiver puts out 120w per channel into 6ohm, or 75w into 8ohm, 5 channels. Speakers are 6 ohm @ 87db sensitivity, so they are relatively hard to power. Total electricity usage playing 5.1 material at 0db gain (really loud): 40 watts and 3.5 amps for the entire receiver. I can't specify how much was going to each channel, but it must be a fraction of that, minus the power required to run the DSP chips, LCD screen, etc. The amount of power amps really put out is overblown. You'll never see the staggering wattage figures on the box in real life. Ever. 

 

Your power measurement test was fine, but won't reflect the actual power delivered to your speakers on an instantaneous basis. Here's why: Using 5.1 material, none of the channel's signals are identical, and that means that it is unlikely that at any moment in time all channels will be producing full power simultaneously.  For that to happen your test signal would have to be a continuous sine wave of equal amplitude produced simultaneously in all channels, a condition not found in program material.  Next, program material is constantly changing and has a rather high peak to average ratio, on the order of 8 to 10dB.  So if you did have peaks at 75 watts, your average would be 7.5 watts.  Now, that doesn't mean you're not actually using that 75 watts, it just means it's very momentary.  Then there's the power supply in your AVR with it's biggie sized filter capacitor storing energy up then dumping it out during high power peaks, then re-charging more slowly over time.  This has the effect of smoothing out peak demands that would be reflected back to the AC line, and producing a long-term average power that may seem unusually low. 

 

Here's your test: Produce equal level, frequency and phase sine waves in all channels, run your gain up to whatever setting you like, and now measure your power...quickly before you blow all your speakers.  You'll now measure the total power delivered from all channels to the speakers plus the quiescent power load of the AVR times the efficiency factor of the AVR (not published, but probably not much over 50-75%.  The difference between the total power used for speakers and AVR and what measure is a result of efficiency, and that power is just heating up your room.  The other variable in your test are an arbitrary 0dB gain (unless you've calibrated the system), and whatever "really loud" is.  Levels are important in power testing as a +3dB change is a doubling in power, so you can't really fudge the levels and get a meaningful power measurement anywhere in the system.  And lastly, the impedance curve of your speakers.  Single figure impedance specs are misleading, they might dip lower or peak higher, and you'd want to know so when you pick your test sine wave frequency you land on a known speaker impedance as well.

 

Now, do you NEED that 75 watts?  Probably do, at least every now and then, if you're playing 5.1 soundtracks near reference.  Considering your front three only at 87dB sensitivity, you'll max at 100dB SPL at 10 ft, which is slightly below what you'd need for real reference level undistorted playback of all soundtracks.  That's because the reference is 85dB SPL, and there's typically 20dB of headroom between average program level and highest recorded peaks.  So, if you play at reference (most people don't), you'll clip early with your setup, probably by 5 - 7dB. 

 

But, in a discussion of speaker wire size, this is all sort of besides the fact.  The circuit of speaker and wires forms a voltage divider which works at all volume levels to modify frequency response, depending on the impedance curve of the speaker. So, less series resistance means less wire-induced response modification.  In the recent post here, I mentioned that a short length of small wire won't matter, and that's true because its total resistance is very small.  

 

Wire-induced response modification is mostly viewed as undesirable, but there may be specific cases when it is of some benefit to the overall performance of the system.  It is not an optimal way to achieve a response modification, and is not generally recognized as desirable.

 

Wire heating is mostly based on long term RMS voltage drop, so the low average power you've found is more appropriate for that discussion.

post #317 of 403

This was a practical test. I don't often listen to sine waves or test tones, and wanted to know how hard the receiver was working on regular 5.1 music material with the volume turned up well beyond the point I usually set it. To be more clear, the receiver was at 0db, reference level, and well beyond my usual setting of about -20 to -30db. Unless amplifiers are able to violate the law of conservation of energy, I don't understand how any single speaker could be receiving more power than what the entire receiver is pulling from the socket.  

 

As far as the wire issue is concerned, what's inside the amp, speakers, or headphones is up to to the engineer, and the choices he/she made in regards to resistance, capacitance, and ampacity for wires within the circuit are beyond my ability to question, or do anything about. But between the amp and speakers, I would prefer to have the least resistance possible within a balanced budget, which translates to gauge thickness. The price difference for thicker wire is small (at reasonable shops): http://www.monoprice.com/products/subdepartment.asp?c_id=102&cp_id=10239 For a few bucks more, I don't really see the downside to investing in thicker wire between amp and speaker. You certainly get a measurable decrease in resistance, and it seems to me the people paying hundreds of dollars for high end speaker wire would be far better off looking for thicker gauge instead. 

post #318 of 403

In most home applications, speaker wire is speaker wire. You can go with heavier gauge if it makes you sleep better at night, but in practice, it's not going to make a lick of difference to the sound. There are much more effective ways to improve sound.

post #319 of 403

Well, peace of mind is really all it comes down to, as I'm sure there wouldn't be an audible difference. But I only have 16awg, which is not an unreasonably thick gauge for a home audio system, and within the range used by most rationally minded radio-shack or monoprice buyers. I didn't go hog-wild on wire.

post #320 of 403
Quote:
Originally Posted by Strangelove424 View Post

Well, peace of mind is really all it comes down to, as I'm sure there wouldn't be an audible difference. But I only have 16awg, which is not an unreasonably thick gauge for a home audio system, and within the range used by most rationally minded radio-shack or monoprice buyers. I didn't go hog-wild on wire.

Want some real peace of mind? Stop fretting! Calculate the actual difference in your speaker wire of choice!

 

When you pick your load, remember, speakers impedance is NOT a single number, it's a variable curve vs frequency.  An 8 ohm speaker can swing around a lot.  Check for an impedance plot of your speakers, try the minimum impedance figure as well as the max.  Also, for fun, try 18ga wire. 

 

http://www.bcae1.com/images/swfs/speakerwireselectorassistant.swf

 

Interesting, yes?  Now that you've seen the wire loss at the minimum impedance and maximum impedance of your speakers, you can translate that into a frequency response change at those impedance points.  

post #321 of 403

Thanks Jaddie, I put this link right into my audio bookmarks folder. Making well informed decisions is what it's all about. I'm having some fun with the numbers. Here's what my calculations looks like for both front and surround speakers, with the 16awg wire, and hypothetically with 12, 18, 20, and 24. My speakers are rated 6ohm, but according to Stereophile, who tested the bookshelf version of my speaker: "The electrical impedance remained above 6 ohms at all frequencies (fig.1, solid trace). The average was closer to 9 ohms, which both means that the SP-BS41-LR... will be an easy load for the partnering amplifier to drive, and suggests that the specified 6 ohms figure is too pessimistic." However, since I have the floorstander, and wanted a conservative number, I stuck with the rated impedance of 6ohms. 

 

The results: (Click to show)

 

FRONTS:

12awg

16awg

18awg

20awg

24awg

 

SURROUNDS:

12awg

 

16awg

18awg

20awg

24awg

 

 

Based on these calculations, would I rush out tomorrow to buy 12awg cables that won't fit under the rug without bulging? Hell no. The amp can keep its  extra .1 dB. That's to say nothing of the fact that most receivers nowadays automatically adjust for varying sensitivities, timings, and distances between speakers. It's a dog chasing it's tail at a certain point. But I do feel secure in my decision to use 16awg, which was originally based on more simplistic ohm/length charts. Seeing the hard numbers, I think I made a good decision. The differences between gauge are not remarkable, and perhaps not even audible in most cases, but (and this is the part I would stress when comparing the gauge differences to differences marketed in "audiophile" wire) at least the differences are measurable and quantifiable. 


Edited by Strangelove424 - 1/26/13 at 9:31pm
post #322 of 403

One of the major developers of an auto-cal system told me (in private) that their system compensates for cable effects regardless of how significant.

post #323 of 403

It might be over-stating the obvious, especially to anyone who tried the calculator, but the choice of speaker wire is based on two factors: length and minimum speaker impedance. Longer and lower require bigger for less wire impact.  

 

Audible response changes are magnitude and bandwidth based, so small changes that affect a large area of response are more audible than small areas, and large changes that affect smaller areas are more audible than small changes that affect small areas. That's why looking at a speaker impedance curve helps predict how audible a wire induced effect will be.

 

Then of course, you can pick the 16ga, run your auto cal, and forget it all. 

post #324 of 403

Just wanted to shout from the roof tops that cables do make a difference and its not small when you get to a certain point.

 

I've had a couple of years concentrating on components and headphones and have even reached a point where I started selling my expensive cables to pay for more dacs amps etc (I'm kind of addicted to buying 2nd hand mid price stuff). Anyways, I was busy rummaging through my draw today to find things to sell. (The dac that I'm testing is a bit bright for my liking and so I'm on the hunt for something else.)  I found a pair of Van den hul MkIII's that one of them quit on me a while ago. I took the ends apart trying find the problem. I found the broken connection and tried to fix it. Pugging it in to try it out and bingo it works now! But not only did it work, but one channel is now very smooth and the other still very annoyingly peaky. The VDH cable plugged into the right side is producing a fine, smooth sound. The Left side with my budget (but massive claim from supplier how good they are) is still harsh at the top and annoying. I'm hearing both cables at once and swapping ears confirms this.

 

I had nearly persuaded myself that cables are cables, as long as they are made correctly to do the job. But I was wrong. Good quality cables are as important as good quality componants. Fact. (because I say so :)

post #325 of 403

There is nothing in the above post resembling actually useful testing, or facts. But your impressions are good to hear, thank you. 

post #326 of 403
Quote:
Originally Posted by LugBug1 View Post

Just wanted to shout from the roof tops that cables do make a difference and its not small when you get to a certain point.

 

I've had a couple of years concentrating on components and headphones and have even reached a point where I started selling my expensive cables to pay for more dacs amps etc (I'm kind of addicted to buying 2nd hand mid price stuff). Anyways, I was busy rummaging through my draw today to find things to sell. (The dac that I'm testing is a bit bright for my liking and so I'm on the hunt for something else.)  I found a pair of Van den hul MkIII's that one of them quit on me a while ago. I took the ends apart trying find the problem. I found the broken connection and tried to fix it. Pugging it in to try it out and bingo it works now! But not only did it work, but one channel is now very smooth and the other still very annoyingly peaky. The VDH cable plugged into the right side is producing a fine, smooth sound. The Left side with my budget (but massive claim from supplier how good they are) is still harsh at the top and annoying. I'm hearing both cables at once and swapping ears confirms this.

 

I had nearly persuaded myself that cables are cables, as long as they are made correctly to do the job. But I was wrong. Good quality cables are as important as good quality componants. Fact. (because I say so :)

 

Connectors can make a difference.

 

It is possible that your budget cable is more transparent and is letting you hear all the flaws of your gear. Your fixed VDH cable could be bandlimited (depending on it's construction, connector, and the rework that you did.) This could mean that your VDH cable could be acting as a low pass filter (fixed equalizer) by removing the high frequency audio content that perhaps your gear is struggling to reproduce (sound harsh and annoying), and quite possibly make your whole rig sound more pleasant.

 

Note however that if your audio rig does a more than acceptable job across the whole audio frequency range, having a bandlimited cable would be holding it back...

post #327 of 403

Using hobbled cables to equalize is like using squared off tires on your car to make sure you keep under the speed limit.

post #328 of 403
Quote:
Originally Posted by ultrabike View Post

 

Connectors can make a difference.

 

It is possible that your budget cable is more transparent and is letting you hear all the flaws of your gear. Your fixed VDH cable could be bandlimited (depending on it's construction, connector, and the rework that you did.) This could mean that your VDH cable could be acting as a low pass filter (fixed equalizer) by removing the high frequency audio content that perhaps your gear is struggling to reproduce (sound harsh and annoying), and quite possibly make your whole rig sound more pleasant.

 

Note however that if your audio rig does a more than acceptable job across the whole audio frequency range, having a bandlimited cable would be holding it back...

Absolutely. I've obviously put both VDH cables in now and the sound is as dynamic as before only without the annoying peaks (think I may have been a bit harsh using the word "harsh" earlier:). I think everyone has their limit in regards to treble peaks. I do appreciate good treble and I tend to focus on this more than any other part of the spectrum because for me it can make or break a sound system. Where as you can always tolerate a little more bass, or even put up with a slight recession in the mids. But too much treble, or bad quality treble can cause fatigue stop you from enjoying the music pretty much instantly. The cables I was using were pure silver. I think the VDH's are a hybrid of carbon, copper and silver as far as I know. The silver cable as you say, may very well be the more transparent one and that is letting everything through.. Warts n'all. 

I was beginning to really think that there was no possible difference in sound between two quality cables. But different materials could make more of a difference than say two copper ones. Obviously I only have my ears for this kind of deliberation but imo its like anything that you've had experience in over a long time. Ears, like taste buds can tell you what is preferable. I must stress I'm very open minded in general and appreciate all that science is, I love my philosophy and have a firm belief that nothing is fact or can be...(I was joking above:) But there has to be a line drawn where you can say "yup that one is better" without our man made maths having the last word. Just saying. ;)    

post #329 of 403
Quote:
Originally Posted by LugBug1 View Post

Absolutely. I've obviously put both VDH cables in now and the sound is as dynamic as before only without the annoying peaks (think I may have been a bit harsh using the word "harsh" earlier:). I think everyone has their limit in regards to treble peaks. I do appreciate good treble and I tend to focus on this more than any other part of the spectrum because for me it can make or break a sound system. Where as you can always tolerate a little more bass, or even put up with a slight recession in the mids. But too much treble, or bad quality treble can cause fatigue stop you from enjoying the music pretty much instantly. The cables I was using were pure silver. I think the VDH's are a hybrid of carbon, copper and silver as far as I know. The silver cable as you say, may very well be the more transparent one and that is letting everything through.. Warts n'all. 

I was beginning to really think that there was no possible difference in sound between two quality cables. But different materials could make more of a difference than say two copper ones. Obviously I only have my ears for this kind of deliberation but imo its like anything that you've had experience in over a long time. Ears, like taste buds can tell you what is preferable. I must stress I'm very open minded in general and appreciate all that science is, I love my philosophy and have a firm belief that nothing is fact or can be...(I was joking above:) But there has to be a line drawn where you can say "yup that one is better" without our man made maths having the last word. Just saying. ;)    

 

I can't stand too much tremble either. And yes, materials can make a difference in the response and performance of a particular set of cables. The problem I see with cables being used as tremble equalizers is that there is too little one can do to fine tune it to make up for our gear deficiencies. Furthermore, it doesn't seem to take much to make consistent and audio frequency range transparent cable these days... Something transducers, some amplifier topologies, and even DAC reconstruction filters may struggle with relatively speaking.

 

Lets say that your headphones have a huge tremble peak at a particular frequency that you are very sensitive. Say this peak is about 10 dB up from the rest of the frequency range. Cable could mitigate this, but typically cable roll off is not frequency selective, and it will take away other frequencies that may not be emphasized. A well implemented equalizer more than likely would do a better job if judiciously applied.

 

As far as math (engineering and physics constructs and concepts in general), I certainly do not feel that it has the last word, but appropriately applied, it has gotten us very far, and IME can be very accurate.


Edited by ultrabike - 1/31/13 at 1:09pm
post #330 of 403
Quote:
Originally Posted by ultrabike View Post

 

I can't stand too much tremble either. And yes, materials can make a difference in the response and performance of a particular set of cables. The problem I see with cables being used as tremble equalizers is that there is too little one can do to fine tune it to make up for our gear deficiencies. Furthermore, it doesn't seem to take much to make consistent and audio frequency range transparent cable these days... Something transducers, some amplifier topologies, and even DAC reconstruction filters may struggle with relatively speaking.

 

Lets say that your headphones have a huge tremble peak at a particular frequency that you are very sensitive. Say this peak is about 10 dB up from the rest of the frequency range. Cable could mitigate this, but typically cable roll off is not frequency selective, and it will take away other frequencies that may not be emphasized. A well implemented equalizer more than likely would do a better job if judiciously applied.

 

As far as math (engineering and physics constructs and concepts in general), I certainly do not feel that it has the last word, but appropriately applied, it has gotten us very far, and IME can be very accurate.

Thats a good point on the cable roll off. Especially with hp's such as the HE500's that I was using. I like the treble on them, but a lot of peeps find them "hot". I can understand that being the case on certain music like classical where the dynamics are full flowing. But then again, full flowing brass is "hot". An equalizer would be able to find the sore point and calm it down more than a cable designed to roll off would, I agree.

My only concern with that theory is; Why would such a well known brand of expensive cables make one of their high end cables "roll off" treble? Make it smooth, yes. But make sure the dynamics are still there as much as poss. Peeps with high end gear (I'm not one of them) don't want cables that roll off anything. They want to hear what their expensive dac has to offer and they don't want cables to interfere with any part of it. The cable should be invisible theoretically. What I'm now hearing tonight with the VDH's is that all the dynamics are still there from top to bottom, only the very top peaks are smoothed out. I would also have to admit that the sound is less bright, or seems to be. But not in any form of dullness or compression. Just more "nice" perhaps softer at the top. But only at the very top.   

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