[Chris J]

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You can more independently manipulate the impedance the headphones and amps see, as well as attenuation, by adding another parallel resistor after R2 and then another series resistor after that. 

and another and another and another and another resistor!
I think an infinite amount of resistors sounds best!
 
Sorry, I couldn't resist!

 

[kozmo]

Quote:

and another and another and another and another resistor!
I think an infinite amount of resistors sounds best!
 

 
That would certainly be a quiet circuit!

 

[alan s]

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Attenuator is a RCA plug with resistors inside it, similar result. You need a resistor network for tube amp regardless.
 
Edit for clarity/safety.
 

 

Do you know if these attenuator adapters are directional ?
 
In other words, are they constructed to work only with a signal moving in one direction ?
 
If that were the case, for example, then it would make a difference if it was attached at an output source as opposed to at an import terminal when connecting the same two devices.
 
I'm thinking the answer is "no" but perhaps someone can correct me if I'm wrong.

 

[khaine1711]

Quote:

 

Do you know if these attenuator adapters are directional ?
 
In other words, are they constructed to work only with a signal moving in one direction ?
 
If that were the case, for example, then it would make a difference if it was attached at an output source as opposed to at an import terminal when connecting the same two devices.
 
I'm thinking the answer is "no" but perhaps someone can correct me if I'm wrong.

They're directional, and need to be plugged at the input terminal of the amplifier's end.
 
The one that can be plug at the source is called source attenuator, and is usually used when you have Naim equipment (DIN socket at the amplifier terminal).

 

[alan s]

Ok, thanks.
 
Still one (or a pair, actually) could be used to attenuate the output signal from a speaker amplifier to a set of headphones, as long as they were oriented correctly (and if they were able to connect to some sort of modified headphone cable).
 

 

[potterma]

Quote:

Ok, thanks.
 
Still one (or a pair, actually) could be used to attenuate the output signal from a speaker amplifier to a set of headphones, as long as they were oriented correctly (and if they were able to connect to some sort of modified headphone cable).
 

I wouldn't!  Those look to be 1/4 watt resistors.    You want to go with power resistors on the output of your speaker amp.

 

[potterma]

Quote:

Interesting stuff.


Power into the actual load, the headphones, should never be more than 100 mW intoa typical headphone, in fact, 10 mW is far more reasonable.
Then work back from there.
If a speaker load is actually necessary ( and it usually isn't in SS amps, but may be useful in tube amps) R1 should be 8 or 10 Ohms, 4 Ohms is a bit excessive..........

Edit:
sorry about deleting the tables, my iPad made a mess out of my original post!

Yeah, I don't know what a real, reasonable number is to plug in for the power to the 'phones.  I started with 3 W to look at resistor power ratings.  3 W is the "Rated Input" for the Yamaha HP-1.  They are rated at 150 ohms, but mine measure 125.  When I get my divider/adapter box built I'll be able to do some actual measurements and adjust the spreadsheet for something closer to reality.

 

[wuwhere]

You can use Mills Resistors, 5w or 12w non-inductive, not cheap.
 
http://www.soniccraft.com/mills_resistors.htm

 

[alan s]

I see. They rate it at a max input of just 20 VRMS.

 

[alan s]

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You can use Mills Resistors, 5w or 12w non-inductive, not cheap.
 

 
That didn't dismay me by itself.
 
But you have to add in a project box (pre-punched, of course), the input and output connectors, and a soldering station.
 
It isn't so much the cost of the items...it's all the time doing research and hunting things down.

 

[wuwhere]

Quote:

 
That didn't dismay me by itself.
 
But you have to add in a project box (pre-punched, of course), the input and output connectors, and a soldering station.
 
It isn't so much the cost of the items...it's all the time doing research and hunting things down.

 
Plastic boxes http://www.allelectronics.com/make-a-store/category/490/project-boxes/1.html
 
Inexpensive speaker terminals http://www.ebay.com/itm/4-Speaker-Cable-Terminals-Copper-Binding-Post-Jack-Gold-/120745885016?pt=Vintage_Electronics_R2&hash=item1c1d03fd58
 
Unless you want to use some nice WBTs or Furutech http://www.vhaudio.com/connectors-speaker.html

 

[alan s]

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Originally Posted by wuwhere
 
 
...... Unless you want to use some nice WBTs or Furutech http://www.vhaudio.com/connectors-speaker.html

 
Wow - that's amazing.
 
I think I'd need to buy a new suit...and put it on... just to visit their web site.

 

[Mambosenior]

Man, this is sounding/looking complicated when it doesn't have to. Just go to Radio Shack and buy two 10ohm-10watt resistors and connect them in parallel to the speaker posts. You need a pigtail XLR adapter on the amp side and a stereo 4-pin XLR on the headphone cable. Done! As long as you have a decent attenuator or device controlling the volume into your amp, and you command the gain with the same attention as you would a speaker set-up, things are good. If you want to get fancier with the resistor set-up later, go for it, but not necessary.

Listening to my HPs (HD-800, HE-5LE, AKG 702, and a loaned T90) via speaker amps has left me plenty happy and I haven't gone near a HP amp in over three months. Owning a number of decent speaker amps, I have no plans to ever buy another dedicated HP amp.

I have difficulty in comprehending the fear-factor of amping with speaker amps. Unless you are a complete novice with stereo equipment and the discipline involved in operating preamps and amps, it's not rocket science!

 

[Chris J]

Yeah, I don't know what a real, reasonable number is to plug in for the power to the 'phones.  I started with 3 W to look at resistor power ratings.  3 W is the "Rated Input" for the Yamaha HP-1.  They are rated at 150 ohms, but mine measure 125.  When I get my divider/adapter box built I'll be able to do some actual measurements and adjust the spreadsheet for something closer to reality.

Try figuring out how much power the headphones take for an SPL of 90 dB.
Yamaha should have a sensitivity figure ( how much voltage they require for s specific SPl) or an efficiency figure (how much power they require for a specific SPL) published somewhere.

3 Watts is more like what it takes to burn the headphones down.

Edit:
I just looked these phones up on the 'net, 94 dB @ 1 mW.
So 1 mW will actually be fairly loud!

the average headphone really doesn't need much power......

 

[Theogenes]

Quote:

I have difficulty in comprehending the fear-factor of amping with speaker amps. Unless you are a complete novice with stereo equipment and the discipline involved in operating preamps and amps, it's not rocket science!

 
I'm sure the guiding principles behind it are relatively simple, particularly for those who have a background that at least tangentially involves dealing with electronics. Some of us (myself most definitely included) come from a perspective of absolutely loving music, which drew us into the gear that reproduces it, but never had any real dealings with what was inside all those metal boxes. If I did something that would be obviously foolish to someone with a greater knowledge level than I and ended up torching my LCD-2, for example, I would be whatever is exponentially worse than 'upset.' 
 
Fortunately though, I know I'm not the only one who reads threads like this in an attempt to learn a little about the dark arts of wires and resistors and whatnots.