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Confused about impedance/sensitvity

post #1 of 25
8/16/10 at 12:12pm
Thread Starter 

I am looking for a DAP to pair with the RE0s. I really do not want to use an amp, so I'd prefer if it was the DAP only. All the Cowon players max-out at 16 ohms and I read that the Sansas are all 16 Ohms (it wasn't listed on the site). The highest impedance I could find was the line of iPods and they were only 32 Ohms. The Sony X series was listed as 5mW+5mW without impedance listed. Could someone please help? 


Edited by faisal2003456 - 8/16/10 at 12:53pm
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Gear mentioned in this thread:

Sandisk Sansa Clip 8GB MP3 Player (Black)
post #2 of 25
8/16/10 at 2:36pm

As long as the impedance of the output is below the impedance of your headphones, it's all good.

Also, most of those players actually have a lower output impedance than 16 ohm - they're listing the amount of power that's put out at that impedance.

 

If you need more volume, go make/buy a cmoy or tpa6120 based amp. Not very expensive.

Don't worry about impedance matching unless you're using a tube amp.

 

If you really really don't want to buy an amp, you'll have to do the math and contact the manufacturer if you need more specific info.

 

Edit: just checked your iems, I'd expect pretty much any portable player can get them up to 100db... why would you want to listen that loud? Only peaks should ever get that loud.


Edited by Dalamar - 8/16/10 at 2:40pm
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post #3 of 25
8/16/10 at 4:11pm
Thread Starter 

Oh, the reason I ask is I have only had one pair of IEMs and they were some random 10 buck Fry's electronics ones. I have no experience with any real IEMs or headphones. I think I'm gonna get the Sennheiser IE6 (after I check out the reviews on head-fi of course).

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post #4 of 25
8/16/10 at 4:46pm

May be relevant: http://www.head-fi.org/forum/thread/168037/db-per-milliwhat-efficiency-vs-sensitivity-vs-how-loud-do-they-really-go

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post #5 of 25
8/16/10 at 5:33pm

If you haven't decided what IEMs you are getting, I would check these out:

 

http://www.head-fi.org/forum/thread/450407/multiple-iem-shootout-v-3

 

http://www.head-fi.org/forum/thread/478568/multi-iem-review-98-iems-compared-xears-td100-ecci-pr300-visang-r01-added-08-11

 

If you want a good DAP, just go with a Sansa Clip+.

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post #6 of 25
8/16/10 at 6:50pm
Thread Starter 

I sent an inquiry to Sansa about the impedance of their players and I don't see the advantage of the Clip+ over the Fuze. The Fuze cost only a bit more on Amazon. The sansa website is USELESS!!! They don't list any specifications of the audio output. I think I'll get Cowon then.

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post #7 of 25
8/16/10 at 6:53pm

Well I had them both at one point and sold the fuze so there are advantages :)

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post #8 of 25
8/16/10 at 6:55pm
Thread Starter 

The clip+ does seem like a better player. No proprietary connectors, the fuze is useless for videos anyways, and it's smaller. I guess if I do decide to go Sansa it'll be the Clip+. One question, if I insert a MicroSD does it all become one big memory pool when I sync to my pc?

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post #9 of 25
8/16/10 at 6:56pm

Well you can use a lod for the fuze which the clip+ can't as well as a longer battery. They both have their pros and cons.

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post #10 of 25
8/16/10 at 6:59pm
Thread Starter 

I'm not interested in the lod. An amp would make it un-portable (I'd carry it in my pocket). If I wanted to use a LOD/amp I'd use my iPod classic with a broken 3.5mm headjack.

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post #11 of 25
8/16/10 at 7:00pm
Thread Starter 

It is one big memory pool though? Or will the internal flash and MicroSD be displayed separately?

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post #12 of 25
8/16/10 at 7:16pm

Those figures you're quoting don't reflect the player's actual output impedence, just the power output for that impedence. And it works nothing like 'player X can drive Y impedance' - you don't drive impedence, you give headphones power.

 

As for output impedence, generally the lower the better, but that's another topic for another time.

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post #13 of 25
8/16/10 at 7:34pm
Thread Starter 

I'm going to try and get an explanation now.

The Cowon J3 specs lists that headphones at an impedance of 16 ohms has 29 mW being supplied to each earbud.

 

So, the RE0 which is listed at 64 ohms impedance would receive 16/64 or 1/4 the amount of power. 29/4=7.25 mW. How do I use that 7.25 mW figure to calculate if they will drive the headphones sufficiently. What figure should I search for?

 

EDIT: So at the Head-Direct site they list the RE0 as having a sensitivity of 100dB/1mW. Does that mean that they will output a volume of 725 dB!!!!!


Edited by faisal2003456 - 8/16/10 at 7:38pm
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post #14 of 25
8/16/10 at 8:00pm
Thread Starter 

So it that possible. RE0 running at 725 dB!!!! I'm sure there is something I am missing. At the Sony website they list the Walkman X series as having an out put of 5mW to each speaker. How do I use that figure alone to know if it can drive a specific pair of headphones?

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post #15 of 25
8/16/10 at 8:42pm

100dB/1mW means it can generate 100dB SPL with 1mW of power. It doesn't say anything about how many mW (max input) the IEM can handle. Also, whether an IEM can be driven well or not also depends on the voltage swing of the amp section, which isn't something you can find in spec (as well as many other factors).

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Gear mentioned in this thread:

Sandisk Sansa Clip 8GB MP3 Player (Black)
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