Headphone Output on my yamaha receiver?? What does it mean?
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jaK

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Hi, I was looking over the manual of my Yamaha RX-V2400 receiver and I found a rating called the "Phones Output" and the value was 150mV/100 Ohm

:p please excuse my ignorance, but what can I deduce from this information?
The headphones that I will be plugging into this receiver are the HD570s which have an impedance of 64 Ohm and a "Load Rating" of 200mW.

Is there any relation between all of these ratings?

Thanks, I am just curious!
 
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NightWoundsTime

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I'm not too qualified to handle this question but I do have a basic idea of why those headphone jacks are sub-par. You said the resistance is 100 Ohms. This is way more than a high quality headamp would run. Basically cheap headphone amps use resistors to step down the signal to headphone levels, and high quality equipment uses a lot of cool electronics to do the same. The problem with resistors is that headphones have a lot of back-signal and this signal can be bottlenecked by the resistor. This resistance can cause distortion in the drivers of your phones.

Hope it helps, my technicalese is a little wanting but that's my understanding of the issue.
 
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No, 150mV/100Ohm means it can deliver 150mV of voltage through 100Ohms of impedance (of the headphone). The 100Ohm rating is not the output impedance.

Really this rating doesn't tell you much. You can be confident that the headphone output from any receiver or integrated amp will be powerful enough to drive all but the most monstrous headphones (like the K1000)... whether it can drive them with a good sound is another matter. And yes, headphone outputs from receivers or integrated amps often are turned down from the speaker output using resistors, so they often have high output impedance. This is bad in theory. But then there's a loyal following for vintage Marantz receivers here, and they have high impedance too. There's probably a lot of other factors for why your average receiver doesn't sound good with headphones.

Heck, OTL tube amps have high impedance too and people love them.
 
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Just a tidbit, the headphone output on my htp-5590 Yamaha reciever sounds like garbage compared to a PPA, or even a cMoy for that matter.
 
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P=i^2*R=V^2/R, so 100mV/100Ohm means, 100mW of power can be supplied using 100Ohm impedance load. In a ideal condition (say if Yamaha can always deliever 100mV regardless of load and its output has 0 ohm impedance), this implies if you plug in 32Ohm, you will get 312mW (or 0.312W). At 64 Ohm, you can expect around 156mW or 0.156W.

Of course this is an ideal condition, but the actual output should not be far off. Often headphone output specs are given with respect to mW/ohm plus a maximum current rating as well. I hope this helps!
 
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Thanks a LOT everyone! Great information!
I was sort of contemplating on wether or not I should get a cMoy or just use my receiver, but I think I will try a cMoy as well
 
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jaK

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Quote:

Originally Posted by go_vtec
P=i^2*R=V^2/R, so 100mV/100Ohm means, 100mW of power can be supplied using 100Ohm impedance load. In a ideal condition (say if Yamaha can always deliever 100mV regardless of load and its output has 0 ohm impedance), this implies if you plug in 32Ohm, you will get 312mW (or 0.312W). At 64 Ohm, you can expect around 156mW or 0.156W.

Of course this is an ideal condition, but the actual output should not be far off. Often headphone output specs are given with respect to mW/ohm plus a maximum current rating as well. I hope this helps!



If the "power handling" (or was it "load rating") of my headphones is only 100mW, then could it be damaged if I used that receiver because it puts out 156mW?

thx!
 
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Quote:

Originally Posted by jaK
could it be damaged if I used that receiver because it puts out 156mW?


No. Your volume knob will limit the power sent. If you're playing on full, 10/10, then you're probably blowing your ears AND headphones up.

Actually, most headphones will handle 150mW no problem in theory. What damages them, is sending clipped / distorted signals - even at low power this could damage them.

This is the beauty of the dedicated headphone amp route: you get CLEAN power and high quality sound. My Yamaha RX596 reciever headphone jack was a joke compared to a simple CMoy design.
 
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My RX-395 yamaha phone jack is too bassy and it smears the details. I think it has a very very very high output impedance. It makes my DT-931 resemble something like the DT-770.
 
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wow thanks again everyone! I am really looking forward to building my cMoy now
 
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go_vtec: You sure your calculation isn't off by, let's say, factor 1000?

Greetings from Hannover!

Manfred / lini
 
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Quote:

Originally Posted by jaK
wow thanks again everyone! I am really looking forward to building my cMoy now



Be sure to check out the DIY section if you run into problems, a ton of people have made cMoys and can help you out. I've also heard that Pimetas are fairly easy to put together on the cheap, so you may want to check them out
 
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Quote:

Originally Posted by highflyin9
Be sure to check out the DIY section if you run into problems, a ton of people have made cMoys and can help you out. I've also heard that Pimetas are fairly easy to put together on the cheap, so you may want to check them out



thx for the tip highflyin9!! If my cMoy is successful, and if I enjoy the sound from my new HD570s (which are due in sometime today [dam you fedex!!]), then I will proceed to build a PIMETA! WEEE!
 
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Quote:

Originally Posted by Joe Bloggs
And yes, headphone outputs from receivers or integrated amps often are turned down from the speaker output using resistors, so they often have high output impedance. This is bad in theory. But then there's a loyal following for vintage Marantz receivers here, and they have high impedance too.


For high impedance Sennheisers (and others), this is not only bad in theory but in practice. Basically what you get is a colored, warm sound with flabby bass -- which might be euphonically appealing to some, but doesn't accurately reflect the music. I've experienced the difference first hand by removing the output resistors from a vintage speaker amp I have, and the result was a much more neutral sound with far better bass control. A low output impedance is an absolute must with some headphones... with others it may not matter as much, or certain cans may require a certain impedance for best results.
 
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