Audio nuts take note

[Mr_Loon]

...


Of course if you don't believe in burn in then that's fine too, let's just not start an argument here about it

OK, how about a discussion


Done a bit of research about this now, interesting stuff. I wouldn't class myself as a true audiophile, though I do appreciate a good sound perhaps a little more than the 'next man'.


I must admit that from my limited understanding of electronics I'm incredibly sceptical about the idea of burn in, however it does strike me as odd to see so much controversy about the issue. It's not like the expensive cables argument where the debate is obviously clouded by financial interest.


What strikes me as really odd is that it would surely be incredibly easy to test whether burn in was real or imaginary, all you'd need is 2 identical systems, 1 burned in, 1 not, 1 set of quality headphones and some passing people willing to try the headphones in both systems and then rate them based on personal perception.

 

[-Tj-]

Perhaps you could go a bit further, testing known frequencies thru the same headphones and using some external device to measure it?

 

[TrashyMG]

Perhaps you could go a bit further, testing known frequencies thru the same headphones and using some external device to measure it?

Captures from an oscilloscope always looks cool..

 

[Grench]

Well, if you're going to get scientific about it...


You'll need multiple units - 50 should do for determining IF there is a phenomena to measure. If you want statistical meaning to it you'll likely need 200 or so.


Anyway, measure them all new on a system so that you can find what the range is between 'identical' units. This should be measuring the actual signal out of the headphone jack - not through speakers. Establish a mean and a standard deviation to understand what the normal differences are within the population.


Then 'burn in' half of the units.


Next, re-measure all of the units. The 25 non-burnt-in should repeat the original results. Differences found would be due to drift on the measurement equipment or aging of the population. The 25 burnt-in should reflect the change due to burn-in when compared to the 25 hold-outs.


The sample isn't huge, so it would likely be more of a directional rather than quantitative result. It should tell you whether there is actually a phenomena to quantify though.

 

[DaMummy]

except that headphones where burn in even matters, start at the $100 mark, and that some manufacturers do the burn in of the devices themselves before selling them

 

[T.T.]

except that headphones where burn in even matters, start at the $100 mark, and that some manufacturers do the burn in of the devices themselves before selling them

I believe he's referring to the pandora's DAC, not the headphones

 

[TrashyMG]

I doubt there would be any noticeable variation on a Digital to Analog converter through out time even with stress testing. I generate test programs for ASIC/Custom Logic semiconductors with DACs and ADCs where I work and there would never be enough variation to be noticeable by human ears. Anything that would vary that much would be thrown out. Although I deal with DACs and ADCs that wouldn't necessarily be used for just audio.


Many companies run a Burn-in stress on electrical components, sometimes heat and overvolting may be used to simulate long use.. This is to see how well the functionality over time is and possible point out manufacturing issues.


Although Headphones make sense there are mechanical parts to it that wear in.

 

[NESnero]

Hey BaDToaD, what media player do you use on Pandora most of the time? Being the audiophile you are, you've probably tried all of them.


Also what headphones do you use when listening to music?

 

[Dimacus]

It's a bit off topic, but this thread got me searching for an article I remember reading an article on how the ear->brain connection really should be described as brain->ear->brain, didn't find it, but i found this link:


http://www.ampzilla2000.com/thequest1.html


It's and interesting read.

 

[Impulss]

Hey guys, I'd like to consider myself as an audiophile, and after reading this thread, It's really helped to convince me to purchase a Pandora. I've recently started to make my own headphone amps, just for fun really, but after reading this, I'd be more than happy to use the Pandora without one, 150mw is impressive! Looking forward to it now!


Thanks for the write up! It's been a good read, I agree with burn in too, just for the record, especially with headphones. I notice the difference in my badly made headphone amps after they're burnt in.

 

[gruso]

Welcome. It's a good time for people who like their media playback, too - looks like we're about to get full DSP access.

 

[Asmo]

What we need now is an audio player that is represented onscreen by one of a selection of classic turntables (Fisher Price if playing mp3), playlist time represented by distance from outer to inner LP rim , and tracks are skipped by lifting and moving the tonearm!


Burn-in time counters for your gear optional.

 

[Binky]

What we need now is an audio player that is represented onscreen by one of a selection of classic turntables (Fisher Price if playing mp3), playlist time represented by distance from outer to inner LP rim , and tracks are skipped by lifting and moving the tonearm!

What about slowly deteriorating sound until you change the needle?


Or the ability to wear out your sound files by overplaying them?

 

[BaDToaD]

Hey BaDToaD, what media player do you use on Pandora most of the time? Being the audiophile you are, you've probably tried all of them.


Also what headphones do you use when listening to music?

I use Audacious as it sounds good to me As for headphones. Check out the review link in my first post. I list all my headphones somewhere in there and add the goldring DR150 and little sony's mentioned earlier.

 

[BaDToaD]

except that headphones where burn in even matters, start at the $100 mark, and that some manufacturers do the burn in of the devices themselves before selling them

Not necessarily true. Good headphones start at much cheaper prices than they did a few years ago with bargains to be had on special offers but on high end gear the effect is more obvious.


FYI Burn in is for electrical components and Bed in is for mechanical stuff like speakers and headphones.

 

[sswam]

"The Pandora absolutely smoked the Dragonfly ..."        hell, yeah!!

( the Dragonfly DAC is a USB audio player 100% scoring hifi "product of the year" which costs almost as much as the Pandora but cannot run emulators )

 

[hmc]

Hi guys,

 

in order to eliminate some of the guesses about stereo volume control issues in the posts above:

 

- yes, for stereo, each channel has an own potentiometer

- these two potentiometers are physically connected, so turning the volume knob synchronically turns both potentioneters

- volume differences on the channels, especially in the low-volume range, are caused by tolerances: the mechanical ones of the axis and angle syncnchronisation, but mainly due to the electrical ones of the (carbon) tracks, on which the pickups glide on, as MWeston already pointed out.

 

Regarding the idea of having only one carbon track / pickup pair for both stereo channels:

Have a look at http://www.beavishifi.com/articles/Volume_Control/

especially at that picture:

http://www.beavishifi.com/articles/Volume_Control/Schematic-Volume-Control-Single-Gang-Potentiometers.gif

 

I think this explains without many words, why this idea would not work.

 

 

And finally about the burn-in theory:

Although I consider myself an audiophile, too, I have not heard of that phenomenon until today, nor did I notice it myself yet. Maybe I'm just too much of an amateur-audiophile rather than a professoinal. ;-)

However, whenever I hear about such phenomenons, that don't seem to be proven yet, and that cause so much controversy, I dare to assume, that this might be a psychologic phenomenon: With time you get used to the sound of the device, so it appears to sound smoother in your subjective reception...?

I can imagine burn-in effects in analog electronics, especially tubes, maybe transistors used in an analogous way. But in digital electronics? DACs? Hm.... *scratchhead*

Bear with me, I can be totally wrong with this of course. ;-)

 

 

[Mr_Loon]

Hey Dredd, interesting find there, I'd never heard of the Dragonfly DAC but if it retails for £215 and does not match the Pandora for Audio Quality then I seriously think that ED should be sending a review model* of the Pandora to what HIFI magazine.

*With pre configured SD Card.

 

[Asmo]

They might reduce a score when they note the lack of a readily available line-out cable - once that's sorted, include one (maybe an audiophile line-out only version) and they'd have little to complain about.

 

[Loonie]

I agree that the sound quality is excellent but I have one issue. I remember seeing it mentioned a while ago (before I got a Pandora) I was wondering if anyone else had the same issue.


If the mixer is set to 75%-100% and I only have to turn the volume wheel a small amount to get to the desired volume level (on headphones) I mainly get volume through the right headphone.


If I put the mixer down to 50% I have to turn the volume wheel more and after a while the left channel catches up and there is hardy any difference between the left and right channels.


When I get a chance I'll put some mono audio on the Pandora and run some tests.


I just wondered if anyone else has encountered this issue.

I believe this issue is caused by headphone impedance. I have a pair of Shure E-425 earbuds that have a comparatively low impedance, something like 18 ohms. As a result, they are quite sensitive, and will be driven with more power, as explained by Ohm's law, current = voltage / resistance. For a fixed voltage applied across a resistance, a lower resistance will pass more current, thus more power will be drawn (power = volts * current). If the amp can provide that power (and the Pandora's amp is a pretty powerful little thing), it will, otherwise it just distorts.

The upshot of this is that when using the Shure, I have to keep the volume at a very low level, almost zero, for comfortable listening. At this position, it is difficult to have equal resistance on each track of the potentiometer, as the wiper is so close to one end. Once the wiper is a couple of degrees beyond that lowest position, the balance is very good, but way too loud through the Shure, because of their low impedance. Another side effect of this increased sensitivity/decreased impedance is it brings the noise floor up a little, which of course won't be affected by turning the software mixer down.

Conversely, my Sennheiser HD25 have an impedance of 75 ohms, and the volume wheel range is far more reasonable, with none of the above issues being present.

If low impedance headphones are to blame, this could probably be corrected with an in-line volume control, or definitely be corrected with a simple home-made attenuator consisting of a 3.5mm plug-to-socket with a 22 ohm resistor in series with each channel.

As for having only a single channel potentiometer to control volume, the only feasible way of doing this would be to use some kind of electronic attenuator on each channel that receive their level setting from the same potentiometer, which of course adds a little more distortion and complicates the design further.