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BecauseICanTBH

Please help me interpret specs on a DAC/Amp

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Posted · Original PosterOP

I have a pair of 250 ohms single-ended Beyerdynamic DT 1990 Pro headphones. I'm currently driving them with a $25 SoundBlaster Play 3 and obviously I'd like to upgrade.

 

I want to get one of these Yamaha integrated amplifiers with DAC functionality, but, being quite new to this, I don't know how to interpret these specs. They don't come right out anywhere and say "this will/won't work with high impedance headphones". 

 

My main 2 questions are: 

  • Why are their power ratings in mV instead of mW?
  • What do the ohms ratings mean for me, in terms of compatibility with 250 ohms headphones?

 

This is the A-U671. This screenshot is from page 17 (PDF page 20) on this manual: https://usa.yamaha.com/files/download/other_assets/3/795413/web_ZS22000_A-U671_om_UL_EnFrEs.pdf

A2.png.dfa6f683871c1e86fe6529b922129e56.png

 

 

 

This is the A-S801. This screenshot is from page 18 (PDF page 22) on this manual: https://usa.yamaha.com/files/download/other_assets/2/332372/A-S801_om_UBL-1.pdf

A1.png.36adb8916931c70116715b56f9a1dd1f.png

 

I appreciate any help on this.

 

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The ohm ratings say that it's rated impedance is 470ohms. Your headphones are 250 ohm so they have almost half of the resistance the amp is rated for, which may make it not reach it's maximum efficiency. That's for theory.

Basing on experience, you should be good. 


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Posted · Original PosterOP
3 minutes ago, RobbinM said:

The ohm ratings say that it's rated impedance is 470ohms. Your headphones are 250 ohm so they have almost half of the resistance the amp is rated for, which may make it not reach it's maximum efficiency. That's for theory.

Basing on experience, you should be good. 

My research tells me that the amp should have 1/8 to 1/10 or less of the impedance that the headphones do. I just didn't understand if the specs were saying (for example in the first one) that the amp's impedance is 32 ohms (or 24?), or that the amp is rated to work with headphones that are 32 ohms... (or 24?).

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The rating means the amplifier is set up to work the best with headphones of 24 ohm (1st amp) or 470 ohm (2nd amp).

The first amp will not see a lot of load with your headphones so it will have to up the voltage a lot to make current flow (which it doesn't want to do).

The second amp will see about half of the load (resisance) it is capable of at max output.

 

To show the difference of how the difference in output load setup translates to actual loudness:

The first amp can handle more than 10 of your headphones at the same time in parallel,

the second can handle two of your headphones in parallel.

If both amps output the exact same power, the one that is set up to handle two headphones at the same time only will have the higher voltage on the line, so that will be louder.

 

But because the power spec is not given in watts, but in volts, it makes a difficult read.

The second amp will have more control over the headphones because of the impedance matching more.

 

But before we get into Ohms law even more, I have to point something out as an audiophile.

Those specs are not great at all. The first amp has high distortion, nice for the kitchen or in your garden shed but no where near audiophile.

Second one is over two times better but still nothing special. Those distortion numbers have to go at least 10x lower to be 'decent'.

 

Get this: https://www.asus.com/us/Essence-Hi-Fi-Audio/Essence_STX_II/

And be done. It has at leas 38 times less distortion than the best of the two amps you point out. Works with your headphone (I have this card too and the amp is powerful)


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Posted · Original PosterOP

Thank you very much for your input. I'll definitely take that card into consideration, although I'm more inclined to get something external for two reasons:

  • EMI inside of my computer (although it looks like that card is pretty well shielded)
  • My computer sits a good 15 feet away from me, I prefer to carry the digital signal that distance rather than analog

Thanks again.

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1 hour ago, RobbinM said:

The ohm ratings say that it's rated impedance is 470ohms. Your headphones are 250 ohm so they have almost half of the resistance the amp is rated for, which may make it not reach it's maximum efficiency. That's for theory.

Basing on experience, you should be good. 

That is not how that works. The ohm rating means nothing at all.

55 minutes ago, BecauseICanTBH said:

My research tells me that the amp should have 1/8 to 1/10 or less of the impedance that the headphones do. I just didn't understand if the specs were saying (for example in the first one) that the amp's impedance is 32 ohms (or 24?), or that the amp is rated to work with headphones that are 32 ohms... (or 24?).

Impedance doesn't mean a headphone is hard to drive, sensitivity does.

30 minutes ago, RobbinM said:

The rating means the amplifier is set up to work the best with headphones of 24 ohm (1st amp) or 470 ohm (2nd amp).

The first amp will not see a lot of load with your headphones so it will have to up the voltage a lot to make current flow (which it doesn't want to do).

The second amp will see about half of the load (resisance) it is capable of at max output.

 

To show the difference of how the difference in output load setup translates to actual loudness:

The first amp can handle more than 10 of your headphones at the same time in parallel,

the second can handle two of your headphones in parallel.

If both amps output the exact same power, the one that is set up to handle two headphones at the same time only will have the higher voltage on the line, so that will be louder.

 

But because the power spec is not given in watts, but in volts, it makes a difficult read.

The second amp will have more control over the headphones because of the impedance matching more.

 

But before we get into Ohms law even more, I have to point something out as an audiophile.

Those specs are not great at all. The first amp has high distortion, nice for the kitchen or in your garden shed but no where near audiophile.

Second one is over two times better but still nothing special. Those distortion numbers have to go at least 10x lower to be 'decent'.

 

Get this: https://www.asus.com/us/Essence-Hi-Fi-Audio/Essence_STX_II/

And be done. It has at leas 38 times less distortion than the best of the two amps you point out. Works with your headphone (I have this card too and the amp is powerful)

I don't even know where to start with this. Literally everything you said here is wrong.

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13 minutes ago, BecauseICanTBH said:

Thank you very much for your input. I'll definitely take that card into consideration, although I'm more inclined to get something external for two reasons:

  • EMI inside of my computer (although it looks like that card is pretty well shielded)
  • My computer sits a good 15 feet away from me, I prefer to carry the digital signal that distance rather than analog

Thanks again.

Oh also avoid sound cards like the plague. Get something like a Schiit stack or something. 

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35 minutes ago, RobbinM said:

The rating means the amplifier is set up to work the best with headphones of 24 ohm (1st amp) or 470 ohm (2nd amp).

The first amp will not see a lot of load with your headphones so it will have to up the voltage a lot to make current flow (which it doesn't want to do).

The second amp will see about half of the load (resisance) it is capable of at max output.

 

To show the difference of how the difference in output load setup translates to actual loudness:

The first amp can handle more than 10 of your headphones at the same time in parallel,

the second can handle two of your headphones in parallel.

If both amps output the exact same power, the one that is set up to handle two headphones at the same time only will have the higher voltage on the line, so that will be louder.

 

But because the power spec is not given in watts, but in volts, it makes a difficult read.

The second amp will have more control over the headphones because of the impedance matching more.

Yeah... None of this is accurate...

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18 minutes ago, Max_Settings said:

That is not how that works. The ohm rating means nothing at all.

Impedance doesn't mean a headphone is hard to drive, sensitivity does.

I don't even know where to start with this. Literally everything you said here is wrong.

The ohm rating stands for nothing. It is mentioned by the manufacturer for... Nothing... Why would that be?

Sensitivity is measured in dB/w. The amount of energy going to the headphones is measured in Watt, which changes with impedance. A higher impedance headphones needs to be driven with a higher voltage to receive the same energy. So both are important.


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2 minutes ago, RobbinM said:

The ohm rating stands for nothing. It is mentioned by the manufacturer for... Nothing... Why would that be?

Sensitivity is measured in dB/w. The amount of energy going to the headphones is measured in Watt, which changes with impedance. A higher impedance headphones needs to be driven with a higher voltage to receive the same energy. So both are important.

Ok so when it comes to driving headphones there is two factors. Impedance and sensitivity. Think of it this way. So on a real headphone amp you will see power ratings given in mW at different ohm ratings. The impedance determines how much power a certain device can push to the headphones at their impedance. Then what happens after that is sensitivity comes into place. That is a measure of how power power in mW is needed to reach a certain volume. So it is actually possible to have a 16ohm headphone that is hard to drive than a 600ohm one. (There actually isn't an example of this in real life but it is possible) So you amp can put more power into 16ohms than 600ohms, but the 16ohm one could require a lot more power to reach a certain volume that the 600ohm one does.

 

What a receiver gives as a rating impedance means basially nothing. And whatever you said about it saying 470ohms and the 1990s only being 250 is not that how that is calculated. Also sound cards are not good for high quality audio FYI.

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We agree on the power thing, I just explained it wrong. My English is not great.

 

You are saying the ohm rating on the amp does not say at what impedance the amp outputs the most power with the lowest distortion?

I'm just saying that if the amp was, say 10 watts at 500ohm, it will want to output 20 watts at 250 ohms which it cannot do with that distortion number. I did mix up series and parallel in my post. I'm tired.

 

About the sound card, I can't argue about that. I haven't measured any "audiophile" DAC's and headphone amplifiers in comparison to my sound card. I did measure my sound card though and it does exceptionally well for a sound card. Noise floor and distortion are exactly as advertised. Did you measure your DAC and headphone amplifier?


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Posted · Original PosterOP
14 hours ago, Max_Settings said:

Ok so when it comes to driving headphones there is two factors. Impedance and sensitivity. Think of it this way. So on a real headphone amp you will see power ratings given in mW at different ohm ratings. The impedance determines how much power a certain device can push to the headphones at their impedance. Then what happens after that is sensitivity comes into place. That is a measure of how power power in mW is needed to reach a certain volume. So it is actually possible to have a 16ohm headphone that is hard to drive than a 600ohm one. (There actually isn't an example of this in real life but it is possible) So you amp can put more power into 16ohms than 600ohms, but the 16ohm one could require a lot more power to reach a certain volume that the 600ohm one does.

 

What a receiver gives as a rating impedance means basially nothing. And whatever you said about it saying 470ohms and the 1990s only being 250 is not that how that is calculated. Also sound cards are not good for high quality audio FYI.

Both you and -BirdiE- are saying that what RobinM said is inaccurate, but perhaps you could elaborate a bit more. I got a little bit of understanding from this post, but not much.

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