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Testing audiophile claims and myths - Page 108

post #1606 of 3674
Quote:
Originally Posted by bigshot View Post

I have a friend who does PA systems for live shows, anything from a small club to an amphitheater. He was doing an outdoor show 50 miles out of town and his assistant forgot to put one of the speaker cables on the truck. He had cabling for one side of the stage but not the other. It was too late to drive back and get it, so he sent his assistant to home depot to buy a spindle of lamp cord. He ran lamp cord with duct tape over it for the full run, expecting there to be problems. When he went to do the sound check and EQ, he couldn't notice any difference at all between the two channels. The show went off perfectly.

 

Clearly your friend is deaf.

 

se

post #1607 of 3674
Quote:
Originally Posted by Yahzi View Post

Everything I've read about damping factor tells me that going from a DF of 20 to 200 is very, very small. So the author is confusing the matter?

 

Huge damping factors look good for marketing, but it should be taken into account that the resistance of the voice coil itself also works against electrical damping, so there are clearly diminishing returns after some point. In other words, going from a DF of 20 to 200 does not actually result in 10 times better damping, more like going from ~95% of what is possible to ~99.5%. It should be noted, though, that loudspeakers can have lower than the nominal impedance at some frequencies, so that increases the effect of the damping factor somewhat.

post #1608 of 3674
Quote:
Originally Posted by jcx View Post

some direct measurements:

http://www.passlabs.com/pdfs/articles/spkrcabl.pdf

 

extreme lengths (movie theater speaker cabling)

http://www.hps4000.com/pages/spksamps/speaker_wire.pdf

....

the John Allen article claims stranded wire gives measurable excess loss at high frequencies – I believe the proximity effect viewpoint is useful in explaining it – the current “wants” to crowd towards the opposing current stream, if the internal strands spiral then there is some emf pushing the current to move from strand to strand at opposite the pitch rate – which involves the higher inter-strand contact resistance

 

I would still caution to employ high skeptism when encountering audiophile cable commetary with terms like "microdiodes" and "strand jumping"

post #1609 of 3674
Thread Starter 

More added to the OP. I do keep hunting and adding as I find tests. bigsmile_face.gif

post #1610 of 3674
Quote:
Originally Posted by Steve Eddy View Post

Damping factor's a bit overrated.

 

Dick Pierce (yeah, I know) had a good article on this in the June 1997 issue of Speaker Builder magazine.

 

se

The Dick Pierce technical paper on "Damping Factor" not the magazine article.

 

Damping Factor: Effects On System Response
Dick Pierce - Professional Audio Development

 

http://www.cartchunk.org/audiotopics/DampingFactor.pdf

 

Bottom line is a damping factor of 5 is probably good enough and a damping factor of 10 definitely is!

 

Frequency response is another issue.

post #1611 of 3674

If I was doing a live sound performance and desperately needed a PA speaker cable.

 

My first choice:

A roll of 14 by 3 plus ground in-wall Romex® (NM). Connect the Red & Black as one wire and the White and bare as the other. This equals 11AWG and the natural twist reduces interference.  But the cable is very stiff and very ugly.

 

Second choice:

Take a heavy AC power extension cord and cut the plugs off it. Replacement plugs are cheap.

 

Third choice:

If the audience is already in the building and I had a nearby spare mic cable, I would jury-rig connects and us it.  It won't be perfect but it will handle lots for audio power for the performance.

post #1612 of 3674
Quote:
Originally Posted by Speedskater View Post

If I was doing a live sound performance and desperately needed a PA speaker cable.

 

My first choice:

A roll of 14 by 3 plus ground in-wall Romex® (NM). Connect the Red & Black as one wire and the White and bare as the other. This equals 11AWG and the natural twist reduces interference.  But the cable is very stiff and very ugly.

 

Second choice:

Take a heavy AC power extension cord and cut the plugs off it. Replacement plugs are cheap.

 

Third choice:

If the audience is already in the building and I had a nearby spare mic cable, I would jury-rig connects and us it.  It won't be perfect but it will handle lots for audio power for the performance.


Aren't PA speakers powered?

post #1613 of 3674
Quote:
Originally Posted by scootsit View Post


Aren't PA speakers powered?

 

 

Not all. 

post #1614 of 3674
Quote:
Originally Posted by liamstrain View Post

Quote:
Originally Posted by scootsit View Post


Aren't PA speakers powered?

 

 

Not all. 


I am correct in thinking that the cabling would vary based on whether or not they were powered, right?

post #1615 of 3674
Quote:
Originally Posted by Speedskater View Post

The Dick Pierce technical paper on "Damping Factor" not the magazine article.

 

Damping Factor: Effects On System Response
Dick Pierce - Professional Audio Development

 

http://www.cartchunk.org/audiotopics/DampingFactor.pdf

 

Bottom line is a damping factor of 5 is probably good enough and a damping factor of 10 definitely is!

 

Thanks. It's the same as was published in Speaker Builder, only it doesn't include the graphs.

 

Quote:
Frequency response is another issue.

 

How do you mean? What other meaningful consequence of damping factor is there beyond altering frequency response?

 

se

post #1616 of 3674
Quote:
Originally Posted by Steve Eddy View Post

What other meaningful consequence of damping factor is there beyond altering frequency response?

Distortion.

post #1617 of 3674

When the high damping factor crowd write about this, I think it's the controlling the woofer cone movement that's the subject of interest.

My frequency response thought is about how the series circuit of the amp's output impedance, the speaker cable's resistance & the speaker's impedance and how this voltage divider will change with frequency.

post #1618 of 3674
Quote:
Originally Posted by Speedskater View Post

When the high damping factor crowd write about this, I think it's the controlling the woofer cone movement that's the subject of interest.

My frequency response thought is about how the series circuit of the amp's output impedance, the speaker cable's resistance & the speaker's impedance and how this voltage divider will change with frequency.

 

Actually, the control over the driver's resonance and distortion occurs through the non-linear frequency response and distortion of the current drawn by it when connected to a voltage source. So, it is not a separate issue.

post #1619 of 3674
Quote:
Originally Posted by xnor View Post

Distortion.

 

Meaningful? What can one expect going from a damping factor of say, 1,000 to 1?

 

se

post #1620 of 3674
Quote:
Originally Posted by stv014 View Post

 

Actually, the control over the driver's resonance and distortion occurs through the non-linear frequency response and distortion of the current drawn by it when connected to a voltage source. So, it is not a separate issue.

 

So then it doesn't matter if the damping factor is greater than 10?

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