Hydrogenaudio Forums > MP3 Player Output Power?

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lepht

Mar 23 2007, 07:31

Hey guys, as you might be able to tell from my question, I'm a bit of an audio newbie. After some intense research I've narrowed my DAP choice into to options: either the Cowon D2 or the Trekstor Vibez. Both players have their advantages and disadvantages, but I like the D2 for size and battery life, and I like the Vibez for build quality and memory.
My question to you guys is: The D2 does 74 mW at 16ohm, while the Vibez does 15 mW at 32ohm. I know the D2 is more powerful, but how do these to figures compare with an equal impedance (ie both at 32 ohm)? To be honest I'd like the Vibez if it's powerful enough to drive unamplified speakers, studio monitors, etc. without needing an external amp. I do realize for these applications an external amp maximizes quality, but portability is a huge factor for me.
Also does anyone know what output power a iPod 30GB 5.5G (my previous DAP) has? Apple doesn't list it in any of the tech specs.
I'm ordering today, so any quick responses will be greatly appreciated

CSMR

Mar 23 2007, 10:58

You are pretty confused about it.
Basically no power is needed to power most studio monitors or other powered speakers because they are amplified. Somewhere between 1W and 1000W to power unamplified speakers depending on use. Not 15mW.

The wattage applies to using the players with headphones, and even then it is not the most important factor: powering headphones there will be more serious problems than lack of power.

woody_woodward

Mar 23 2007, 13:13

Neither device will provide adequate output for unpowered speakers. Difference in earphone sensitivity will be more significant than specified output for the two devices. Short answer: You'll be happy with either if you use phones. You'll be happy with neither if you use speakers.

lepht

Mar 23 2007, 15:44

QUOTE(woody_woodward @ Mar 23 2007, 14:13)

I guess I should have been more specific. In the past I've used a pair of small computer speakers (unpowered) with my iPod nano and iPod Video 5.5g. The nano was able to power them to an acceptable level (Podcasts in the shower!) while the iPod Video not so much. I know I can get a small pair of powered speakers, but honestly I'm at an impasse when it comes to choosing between these two players, so I'm looking for any small conveniences to set them apart. I can't find the published output power of either iPod to use in comparison to these players, but I have no doubt the D2 would power them perfectly. In comparison, the Vibez's power looks fairly paltry. I guess I'm kind of asking how Vibez's power output looks compared to average, especially since I have heard one person mention the volume wasn't to their satisfaction.

EDIT: It seems I may have found the answer to my question on the dapreview forums. Someone has quoted

QUOTE

28 . 3 mW (L ) + 28 .3 mW ( R) , 16 ohm

This makes it seem as if the spec on the Trekstor site may have been to comply with French/European volume limits, as the player asks if you live in France when you first boot it. Does anyone know how mW scales with Ohm? Is it a linear relationship?

lepht

Mar 23 2007, 16:47

Ok, well I've found my answers, although most people here don't seem to care, hopefully some other curious individual will find this info useful. It turns out the French/EU volume limiting is active and the quoted output figure. DobsOnly in his initial review on the Head-Fi forums had this to say:

QUOTE

If there is a glaring negative about the VibeZ, IMO, it would be that it is under powered when compared to the Karma. With the HF-1 the VibeZ at full volume is just getting there. I listen to my Karma at 18 to 22 and can’t get there at 30 on the VibeZ. My Karma would drive my HD600’s to decent levels and the VibeZ is anemic and thin sounding at 30 connected to them. Through more effecient cans, volume levels reached are about the same as the 2nd gen Nano and ZenV+ which I found weak even at the highest levels.

A month later, he updated it with this info:

QUOTE

The VibeZ is setup with a selection during startup that limits the volume level if you live in France. I like some of the others were certain we answered this question NO on initial startup. Once it is set there is no way of checking this setting. After reading a few of these I decided it would be worth a try. So tonight I hit the reset and made absolutely sure I selected NO on initialization. All I can say is unbelievable The difference is like night and day.

QUOTE

Now I will say what I haven't said yet. The VibeZ, when correctly configured, is a very worthy successor to the Rio Karma and could be, IMHO, the most under estimated DAP discussed in these forums. The change is that dramatic.

He also mentions the headphones used are Sennheiser HD600s, which have a 300 ohm impedance(!).
My fears have been allayed, my Vibez has been ordered, and I'm incredibly psyched

CSMR

Mar 23 2007, 18:53

So-called "computer speakers" are powered. That is why you can use them with a computer with no external amp.

lepht

Mar 23 2007, 19:18

Nope, these speakers are most definitely unpowered (passive:http://www.mmproductions.co.uk/faqspe4.html) speakers. They're completely powered by the MP3 player itself, barring any Tesla-like magical grabbing of electricity out of the air. Now can anyone answer my questions of impedance, then CSMR can try to pick holes in all of the unrelated things after. This is very reminiscent of dealing with slashdot users, willing to criticize while ignoring the actual question/intent of the others.

Mercurio

Mar 24 2007, 20:12

As far I know power transfer is related to additional parameters, like the output resistance of the headphone amp. If you assume it is 0, and that the amp act as a voltage source, then the power of the D2 on 32 ohm will be 37mW. But I truly think the previous answers of CSMR and Woody are more useful than this calculation.

QUOTE(lepht @ Mar 23 2007, 17:18)

Usually computer speakers are powered, and I would not blame CSMR and Woody if they don't know about something like Sony SRS-P11Q. I just discovered them after I read this thread ^^'', but I can't believe there are also "Studio Monitors" of this kind.
Frequency Response - 200 - 10kHz
Total Harmonic Distortion - <10%THD, 1kHZ

I would prefer a pair of battery-powered ones, that doesn't have the problem to be driven from the dap headphone amp, and can't sound worse.

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