[Split]Technical split from: Pear Cable CEO Calls James Randi's $1 Million Offer a Ho

[Dan O.]

I don't get it. I mean, isn't it obvious that there are differences in cables? A steel cable will definitely sound worse than a copper cable. Ofcourse after you get over a certain threshold it doesn't matter anymore and studio quality cables should be enough for everybody.

Until the cables are extremely long or you are talking about very high frequencies, the electrical properties of any cable can be modeled by three parameters: Resistance, Inductance and Capacitance. Only resistance will be affected by the material the conductors are made of and that can be compensated for by making the conductors thicker. The effect of all these parameters on the sound depends also on the construction of the amp and speakers. Increasing the resistance of the cable can help flatten the speaker response in some cases, or make it worse in others.

Headphone cables have other constraints which limit the practical size of the conductors. You don't want the weight or stiffness of #12 wires hanging on your neck. The whole cable on your hd650 phones is about the size of 1 #12 conductor without the insulation.

The material of the conductor makes a difference for mechanical properties. But for other than the bulk resistance, the electrons don't care. We are talking about mechanical considerations of the speaker cables and even for the worst case construction it's going to be hard to detect a difference. Now maybe if I stretched the wires like piano strings so they can resonate...


ETA: Now who would ever guess that "Specially modulated connecting cable" simply means it has connectors on both ends.

 

[Paulhoff]

I don't get it. I mean, isn't it obvious that there are differences in cables? A steel cable will definitely sound worse than a copper cable. Of course after you get over a certain threshold it doesn't matter anymore and studio quality cables should be enough for everybody.
We are not talking about Ferrous metals.
I have here one of the many replacement cables (snake oil if you will) for the hd650 phones. Now there's definitely a difference between it and the stock one. The difference is simple, it has less bass and more treble. That's it really.
NO, The impedance of short wire (less then 20 FT let's say) at audio frequences is almost nothing.
Is it ********? Am I hearing differences? No. I actually prefer the stock cable so I'm not even biased to prefer the "upgraded" cable. But the difference is there anyway and should be pretty easy to spot blindfolded.
NO, The impedance of short wire (less then 20 FT let's say) at audio frequences is almost nothing.
You can change the sound frequency of a phone by changing the output impedance somewhat and I think that's what most of these cables are simply doing.
The impedance of short wire (less then 20 FT let's say) at audio frequences is almost nothing.
Now what about amplifiers, do they all sound the same? Not by a long shot. There's another candidate for the 1 million dollar challenge

We are not talking about amplifiers.

Paul

 

[Paulhoff]

Burning in cable, geeeee, why doesn't thhe pre-stretch them too to relieve the tension in the cable for smother highs.

Paul

 

[rsaavedra]

I calculated the dB differences in an earlier post. At 20kHz, the difference is 4.8dB, however, most adults can't hear that high. My own hearing runs out at 17kHz so I'm not too concerned with what happens at 20kHz.

For the dB impaired, here are the equations to use:

http://en.wikipedia.org/wiki/Decibels#Amplitude.2C_voltage_and_current

To calculate dB, just pick the voltages off the graph and plug them into the equation.

Haven't seen your earlier post.

Power amplifiers can easily output more than 30 volts AC measured at speaker terminals. It is odd that the voltage measured at speaker terminals in Pear's graph are so low. It is not clear whether that graph shows relative voltage differences between the cables compared to some reference they chose, instead of actual absolute voltage values measured at the speaker terminals given some arbitrarily chosen (and stragely low) volume in the amp chosen to do the comparison.

It would make a major difference in dB's to compare 1.5 vs. 1.0 volts (a 0.5 volt difference), instead of 40.5 vs. 40.0 (also 0.5 volts difference) measured at speaker terminals. See my point now?

Thanks for the Wikipedia link, and I send you back your "for the dB impaired" part

 

[sol invictus]

Power amplifiers can easily output more than 30 volts AC measured at speaker terminals. It is odd that the voltage measured at speaker terminals in Pear's graph are so low.

Not really. Into 4 ohm speakers 30V would be more than 200 watts, which would drive all but the most powerful solid state amps into clipping. The sound level produced by that depends on the speakers, but for a typical sensitivity (say 87dB) that would give a sound pressure level of 110 dB at one meter - loud enough to damage your hearing.

At .5V the SPL would be around 75dB, which is still pretty loud.

Human hearing is logarithmic, so funny things like that can be true.

 

[krabapple]

Or perhaps someone could demonstrate the frequency response graph on their website was inaccurate ? If that graph was true pretty much any one of us could pass a DBT.

Someone on AVSForum has measured 'normal' cables, and his results don't jibe with those on Pear's website, at least as regards the 'competitor' cable they compared to their Pears.

http://www.avsforum.com/avs-vb/showthread.php?p=11901506#post11901506

http://www.avsforum.com/avs-vb/showthread.php?p=11907258#post11907258

heres' the original Pear graph for comparison

http://www.avsforum.com/avs-vb/showthread.php?p=11850171#post11850171

heaven knows what 'competitor' cable thye used, but whatever it was, generic 14g or 12g outperforms it.

 

[rsaavedra]

Not really. Into 4 ohm speakers 30V would be more than 200 watts, which would drive all but the most powerful solid state amps into clipping?

What? Sorry but you are wrong. We are talking about a context of audiophile cables, the setup to test them most certainly included good quality amps. Even less than top-notch quality amps can match and exceed those numbers you quote easily, without clipping.

Just as examples in alphabetical order, and these are not even the most powerful amps in each of the brands listed here, just some good amp brands I keep bookmarks of:

Balanced Audio Technologies VK-300x: 300 watts into 4 ohms
http://www.balanced.com/

Bryston 7B SST: 900 watts into 4 ohms
http://www.bryston.ca/7bsst_m.html

Krell Kav-400xi: 400 watts into 4 ohms:
http://www.krellonline.com/krell_component.php?id=42&page=kav400xi

Perreaux Prisma 350: 600 watts into 4 ohms
http://www.perreaux.com/product.php?idp=44

Plinius SA Reference: 1000 watts continuous into 8 ohms in balanced mono mode
http://www.pliniusaudio.com/documents/downloads/plinius_sarefbrochure.pdf

PS Audio GCA-500: 1000 watts into 4 ohms
http://www.psaudio.com/products/gca_amplifier_specifications.asp

Rotel RB 1091: 1000 watts into 4 ohms
http://www.rotel.com/NA/products/ProductDetails.htm?Id=4&Tab=2&Pic=1

 

[sol invictus]

Those are some of the beefiest amps money can buy - and quality doesn't equal power rating. The correct strategy is to use an amp with sufficient power and good specs below clipping, not the one with the greatest possible wattage. Many audiophiles use 10 or 20W/channel tube amps.

My SS amp is rated around 80W/channel into 4 ohms (although with 4 channels powering each speaker that's around 320W per speaker), and it's quite high quality.

Anyway, you ignored the point of my post, which is that .5V RMS is enough to produce a loud level of sound from ordinary speakers. Try it yourself if you don't believe me.

 

[rsaavedra]

Anyway, you ignored the point of my post, which is that .5V RMS is enough to produce a loud level of sound from ordinary speakers. Try it yourself if you don't believe me.

No in fact I didn't ignore it, was going to address it after clearing up the other point first, which I think I did.

You say .5 V provide 75 dB.

On the one hand, 75 dB is really not loud enough, for instance, it is not realistically loud for any listening session trying to portray an orchestra, or a rock band, or even a Jazz session, or vocals.

On the other hand, 75 dB measured where? And I'm talking now about dBs of the actual sound pressure level measured in front of the speakers. Besides voltage at speaker terminals, final perceived sound pressure level will depend on the speakers's sensitivity, and most importantly, on how far you are from the speakers. 75 dB measured at 1 meter from the speaker drivers? That would be way less than satisfactory.

At the sweet spot (the point wherever the listener sits in front of the speakers to hear the music) the average music volume should usually be around 80-85 dB (this depends on the music of course, but it's a general number used with calibration pink-noise tracks recorded at specific volumes, used for calibrating stereo and home theater rigs). With good dynamic range of speakers that means when the music gets really loud the listener will perceive realistically loud peaks and bursts of 90 dB and even way higher, once again, at the sweet spot. So 75 dB at the sweet spot in general is not satisfactory, much less if it's 75 dB at 1 meter from the speaker drivers, as usually measured in anechoic chambers.

 

[sol invictus]

No in fact I didn't ignore it, was going to address it after clearing up the other point first, which I think I did.

If providing an extreme set of examples and claiming they are typical counts are "clearing up", then yes, you did. Not to mention ignoring once again the primary point - that you claim .5V is "strangely low", and yet most people listen at levels well below that.

You say .5 V provide 75 dB.

On the one hand, 75 dB is really not loud enough, for instance, it is not realistically loud for any listening session trying to portray an orchestra, or a rock band, or even a Jazz session, or vocals.

That very much depends. Almost no one listens to orchestral music at "realistic" levels, if by that you mean how loud the sound would be if the performers were in your listening room (not that they would fit). In fact very few audio systems are even capable of that.

As for vocals, normal speaking volume is well below 75dB. Only loud singing or shouting would rise much above it.

Right now we're listening to Ravi Shankar (at realistic levels for a sitar and tabla). I just went and measured the voltage going to the midrange driver: it averages around .1V, peaks at perhaps .2V.

On the other hand, 75 dB measured where? And I'm talking now about dBs of the actual sound pressure level measured in front of the speakers. Besides voltage at speaker terminals, final perceived sound pressure level will depend on the speakers's sensitivity, and most importantly, on how far you are from the speakers. 75 dB measured at 1 meter from the speaker drivers? That would be way less than satisfactory.

You might want to learn a little bit about speakers and audio systems. Speaker sensitivity is typically measured 1m from the drivers. The figure I quoted assumed 87dB/W at that point.

At the sweet spot (the point wherever the listener sits in front of the speakers to hear the music) the average music volume should usually be around 80-85 dB (this depends on the music of course, but it's a general number used with calibration pink-noise tracks recorded at specific volumes, used for calibrating stereo and home theater rigs). With good dynamic range of speakers that means when the music gets really loud the listener will perceive realistically loud peaks and bursts of 90 dB and even way higher, once again, at the sweet spot. So 75 dB at the sweet spot in general is not satisfactory, much less if it's 75 dB at 1 meter from the speaker drivers, as usually measured in anechoic chambers.

That's interesting, because 85dB will cause hearing damage from prolonged exposure. If you habitually listen at that level, maybe that explains why you have a need for 1,000W amplifiers?

 

[rsaavedra]

If you habitually listen at that level, maybe that explains why you have a need for 1,000W amplifiers?

No I don't need 1000w amplifiers, and I don't habitually listen at that level. One thing is to calibrate a system with a specific calibration tone at that level, another is the volume at which the recorded music will sound.

Sol invictus apparently you might want to learn a bit more about speakers and amps and recording levels, and then reread my post. Well, it's also possible I wasn't clear enough of course

In case it wasn't obvious from my post, the farther away you have your listening position from the speakers, the louder they must play to yield the same specific perceived (Desired) volume at that sweet spot, hence the higher voltage they need to get at the speaker terminals. So if you calibrate your system with a calibration track playing so that at your listening spot your calibration track sounds sounds at let's say 85 dB, that might mean at 1 m from the drivers the SPL meters might be showing 96 dBs, or even more. It all depends on how large your room is, and how powerful your rig is of course.

Once again, notice that playing the calibration track at 85 dB measured at the sweet spot doesn't mean all music will be perceived at that level there. I usually play my music (when I want reallistic loudness) at calibration around 80 dB. Depending on the music that can be tolerably realistic, but some compressed rock songs are uncomfortably loud at those levels.

One final point. Check your sources. 85 dB is not really a hearing damage risk. The really dangerous zone starts at 90 dB, and 90 dB cause hearing damage only after sustained exposure for 8 or more hours. For more details:

http://headwize.com/articles/hearing_art.htm

PS. As the page in that link indicates, those exposure times are too high for hearing safety according to some experts. And also, posting a link to that table doesn't mean I would encourage anyone to listen to music at sustained 85 dB though. I particularly don't.

 

[sol invictus]

Once again, notice that playing the calibration track at 85 dB measured at the sweet spot doesn't mean all music will be perceived at that level there.

For the third time you make a lot of irrelevant noise and ignore the salient point - that .5V is rather loud, given a typical setup.

Many speakers have a sensitivity well above 87 dB/Wm, meaning that even two or three meters away the level would be higher than my estimate. Furthermore most people don't live in a field or suspended in empty space, so SPL doesn't fall off very quickly with distance from the speakers.

One final point. Check your sources. 85 dB is not really a hearing damage risk. The really dangerous zone starts at 90 dB, and 90 dB cause hearing damage only after sustained exposure for 8 or more hours.
...
And also, posting a link to that table doesn't mean I would encourage anyone to listen to music at sustained 85 dB though. I particularly don't.

Impressive - you contradicted yourself in your own post. Congratulations.

Here (American Speech-Language-Hearing
Association) http://www.asha.org/public/hearing/disorders/noise.htm sounds above 60 dB are classified as "very loud", and sounds above 80 db as risky for hearing loss.

Are you really going to keep arguing?

 

[rsaavedra]

For the third time you make a lot of irrelevant noise and ignore the salient point - that .5V is rather loud, given a typical setup.

No I haven't ignored it, in fact I addressed it, you just keep ignoring my challenges to your claim. And all the other info I included is really not irrelevant noise, imho.

Once again, 75 dB is not rather loud (in particular measured at 1m from the speaker, and in spite of room gain), even on a typical setup. You might want to define typical setup, but I don't need you to define it for me, you haven't read my posts properly it seems. Read again.

Impressive - you contradicted yourself in your own post. Congratulations.

Well, once again, no I haven't. Read again, and check your definition of contradiction.

 

[rsaavedra]

so SPL doesn't fall off very quickly with distance from the speakers.

You lose 6 dB every time you double the distance. Or equivalently, you gain 6 dB every time you halve the distance from sound source.

 

[Gr8wight]

You lose 6 dB every time you double the distance. Or equivalently, you gain 6 dB every time you halve the distance from sound source.

As Sol pointed out, in anechoic circumstances only, which describes absolutely no-one's listening room.

I don't quite understand why this thread has devolved into a discussion of technical aspects of audio gear, as they have absolutely nothing to do with the challenge.

 

[Gr8wight]

Sorry for the double post.

 

[rsaavedra]

I don't quite understand why this thread has devolved into a discussion of technical aspects of audio gear, as they have absolutely nothing to do with the challenge.

Agree yes, questioning and clarifying some of the technical statements issued here has turned into a whole set of truly off-topic posts, apologies for my contribution to that.

PS. To close my technical straying, or for those interested in the technical exchange discussed here: http://www.enjoythemusic.com/magazine/manufacture/0907/

 

[rsaavedra]

You do realize that's written by a manufacturer that sells amplifiers (among other products), don't you? It's just an ad to try to sell you a much more powerful amp than you need.

Wrong Sol. Allan Lofft (http://www.audiolofftreport.com/about-alan-lofft.html) belongs to Axiom audio (http://www.axiomaudio.com/products.html), a company that traditionally (~27 years) manufactures speakers, not amplifiers. Only now they have very recently manufactured one amplifier, just one model, you can see it here: http://www.axiomaudio.com/A1400-8.html

By the way I have no commercial or even personal connection to any of the above. I just know the brand as a consumer, and know those speakers have been awarded some Editor's choice, best values etc.

Most importantly, I also know enough about audio and electronics (built an amp myself after all) to realize that the guy knows pretty well what he is talking about (honestly as opposed to you, at least within the scope of the technical things we discussed.) And I also realize the guys explains everything in the link I posted in my previous post quite clearly. In particular the demands on power for reallistic playback, and the fact that 70-ish 80-ish dB as an upper bound is not reallistic headroom and is not loud enough at all.

I also hope you do realize what Mr. Lofft wrote in that article is not an ad, but a simplified technical explanation, kind of aiming at the lay person, even though it's rather techno oriented. You can interpret it whichever way you'd like of course.

Anyway this is also off-topic. We should really take further technical exchanges in another thread to avoid bringing more annoyance to other forum members. Pm me if you'd like.

 

[sol invictus]

Wrong Sol. Allan Lofft (http://www.audiolofftreport.com/about-alan-lofft.html) belongs to Axiom audio (http://www.axiomaudio.com/products.html), a company that traditionally (~27 years) manufactures speakers, not amplifiers. Only now they have very recently manufactured one amplifier, just one model, you can see it here: http://www.axiomaudio.com/A1400-8.html

No, not "wrong": right! Thanks for confirming (again) exactly what I said:

You do realize that's written by a manufacturer that sells amplifiers (among other products), don't you?

And the amp they sell just happens to be insanely and unecessarily overpowered. What a coincidence that they then produce a "scientific" discussion of why it's necessary. And what a revelation to the rest of the world: all the musicians, mixing engineers, music producers, and audiophiles that have been struggling along with totally inadequate amplification for so long.

If you really think that was an unbiased, accurate, scientific assesment, well... there's one born every minute, I guess.

 

[rsaavedra]

all the musicians, mixing engineers, music producers, and audiophiles that have been struggling along with totally inadequate amplification for so long.

And that, of course, is certainly an unbiased, accurate, and scientific assessment. Accurately explaining the relationship between output dB volume and power requirements certainly isn't accurate and unbiased compared to that

Sol, your prejudices are only too obvious. You are not challenging his technical claims, you are just resorting to some form of fallacious arguments to protect your belief that your amp can handle all power requirements in the world for realistic playback. Hmm.... Very suitable for a critical thinker. In your own words, there's one born every minute