[delenda est Sony]

Hmm, powering headphones is as baffling a subject to me as the Knicks at the moment, so I'd thought I would publicly admit my ignorance and plead for help...

First, my Sony DFJ61 puts out ".5 mW + .5 mW" through its headphone jack. Why are there 2 numbers? As there is a post up about some 20 mW player from Denver, I take it this means the Denver model is 20 times more powerful than my Sony? How much power does this board's favorite the Pans CT570 put out?

Second, the Sonys line out jack puts out "0.7 V", Why the change in measurement from mWatts to Volts? And again how does this rank comparatively to other models?

Finally, how much power comparatively does the average receiver jack or headphone amp put out?

thanks for any help--I am just wondering if it's worth it to upgrade my PCDP to some other more powerful model (as I don't want to carry a "portable" amp around with me.)

 

[alfaudio]

1. Firstly, there is perhaps some misprinting on your SONY'S I/B, as far as I know, most(almost all) sony's new pcdps have a earphone out put as 5mW+5mW@16ohm, that is each of L/R chanel can output a 5mW power to a 16ohm earphone, so if your earphone is 32ohm, the output power may drop to 2.5mW. While other products may rate the output power at different duty resistance, or with a sum of both channel.

2.Regarding line out, it is always rated as **V@**kohm, normally, sony's PCD line out is about 0.5V@47kohm. The line out capability can not be rated as mW,because when connected to a amplifer(lineout is designed to be connected to an amp), the only thing we normally consider is voltage as the input resistance of the amplier is normally so high that it absorb no current(too low to be calculated).

3.Normally, a lot of CD ROM can output 10mW@16ohm, which is bigger than most of pcdp as new pcdp always sacrifice the output power for longer running time .

 

[blr]

Well, let me see.
5 plus 5 mW=5 mW per channel=2x5 mW. Simply means thet both channels are powered to 5 mW.

My (and others) Denvers are not at all 20 times more powerful. Doubling the power results in about 3 dB gain. So, this means that the Denver will deliver about 6 dB more SPL than your Sony.
How well your portable will power your cans depends on two things (not talking quality of sound here).
First, the amp power, and second, the sensitivity and impedance of the cans. It is expressed usually in dB SPL at 1 mW of power. The higher the sensitivity, louder they go. The higher the impedance, the more difficult they're to drive

That,s just a brief explanation.
Sorry gotta go.

 

[redshifter]

alfaudio,
what is the best way to get a sony headphone jack to mimic a line out in actual use? turn the volume to max to increase the voltage?

 

[pedxing]

Quote:

Originally posted by redshifter alfaudio, what is the best way to get a sony headphone jack to mimic a line out in actual use? turn the volume to max to increase the voltage?

Each pcdp's heapdhone jack is made differently, so the volume level would be different for each model. Cranking up to the max volume with most sony pcdp will probably yield distorted outputs.

If you compare the line out and the headphone jack of a pcdp, the quality of the headphone jack is usually worse in quality if not the same than the line out. All three of my sony pcdp's heapdhone jacks sound inferior compared to their line outs. My EJ725 has the largest difference in sound quality between its heapdhone jack and line out.

 

[redshifter]

it is a sony md recorder, specifically the mz-r70. i asked this question before but never really got a good answer. it has no line out.

i only have one pcdp, the sony d-777. the headphone jack sounds almost as good as the line out. there are some who prefer the headphone jack on this model.

i want to use my mdr with a cha47 amp. i have heard "turn it all the way up; 3/4 of the way up; 1/2 way up"... i can alway go by what sounds best to me, but was wondering if there was any hard evidence for any particular volume setting. for example, does a good line out require more current than voltage, and how can this best be mimicked by a headphone jack?

 

[alfaudio]

Quote:

Originally posted by redshifter alfaudio, what is the best way to get a sony headphone jack to mimic a line out in actual use? turn the volume to max to increase the voltage?

You can calculate the max output voltage from the head phone out is approximately 0.28V with the condition of 5mW/16ohm, which is a little bit higher than the standard line out on my R55(I remember it was 0.2V/47kohm but I lost the I/B) so you can just set the volum to the max without much problem. Compare that voltage to your d-777 pcdp which normally has an lineout voltage of 0.5V, the volum from MD will be a little over 3dB lower, anyway, it is not a great loss.

Granted, setting in a lower volum will theoretically reduce distortion as most amplifer circuits work with lest distortion in medial level(say 1/2~3/4 of full range) but as yet, if you can not tell the different, just go with the max. Actually, on my R55, I can not feel any distortion when the earphone out is set to the max. While to connect an amplifer from a line out will probably improve the sound, especially in those newer models which are fitted with a crap earphone amp just for battery saving. I have no idea about your R70, but on my R55, connecting from the line out do improve the sound.

 

[delenda est Sony]

thank you lads!

Much appreciated. My Sonys lame output is all the more disgraced by your erudite explanations. A JMT amp is inbound to address these issues of firepower deficiency...

Now all of you come over to this thread:

http://www.head-fi.org/forums/showth...&threadid=8873

and see if you can help poor Trancegeek and his odd problem with distortion on the Senn 280s. It sounds like something engineerry...

 

[redshifter]

thanks alfaudio for the technical explaination. this headphone/line out thing has been bugging me for a while. i'll report back with results after my cha47 arrives (shipped today!!).