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Speaker amps for headphones
Aug 8, 2013 at 11:13 PM Post #586 of 3,871
Quote:
chris j said:
The "power meters" will be volt meters referenced to 8 Ohms.

3 Watts into an 8 Ohm load works out to 0.48 Watts into a 50 Ohm load.
Click to expand...

Very astute, Chris J!
 
I did some measurements with a digital oscilloscope and HE-6's on a 125 W into 8 ohm Carver M-200t speaker amp (20 W into 50 ohms, for those keeping track).
 
Now my particular set of HE-6's measure 61.3 (L) and 61.6 (R) ohms.  I called it 61 ohms per side in my calcs...  With a 5 second RMS window, I measured 0.43 W RMS.  Bass peaks within that window hit a max of 6.6 W peak (NOT peak-to-peak).  
 
As an interesting note, that works out to only 80 mA RMS and 330 mA peak into the headphones.
 
Aug 9, 2013 at 6:56 AM Post #587 of 3,871
potterma said:
Very astute, Chris J!

I did some measurements with a digital oscilloscope and HE-6's on a 125 W into 8 ohm Carver M-200t speaker amp (20 W into 50 ohms, for those keeping track).

Now my particular set of HE-6's measure 61.3 (L) and 61.6 (R) ohms.  I called it 61 ohms per side in my calcs...  With a 5 second RMS window, I measured 0.43 W RMS.  Bass peaks within that window hit a max of 6.6 W peak (NOT peak-to-peak).  

As an interesting note, that works out to only 80 mA RMS and 330 mA peak into the headphones.
Click to expand...


What shocks and stuns me is how much power those headphones use!

No wonder Schiit developed the Lyr and Bryston developed the BHA-1!
 
Aug 9, 2013 at 3:27 PM Post #588 of 3,871
Gary.. how easy was it to control low-volume listening with the Millenia+resistor box?
 
I've ordered a resistor box from Jan.. appropriate ICs and such are on the way (from another vendor).. will give the HD800 a spin on this with a T-class amp I have laying around.. if the performance improvement is impressive, enough.. I'll swing for the Millenia.  I'd go for the Cyclops.. but I think it might be a little too big for where I need to situate my amp.
 
Thanks again for chronicling your speaker amp-to-headphones adventures.. it was very helpful.. if the OP doesn't anticipate indexing the relevant posts in this thread, it wouldn't be a bad idea to start your own thread and link your posts/reviews.
 
Aug 9, 2013 at 4:28 PM Post #589 of 3,871
Flysweep....
It's certainly your call, but I am not sure how much the T amp you have will let you know what something like the Millenia will sound like (or the Odyssey amp for that matter). If you do some Googling about the Millenia, it's been used with ultra expensive speaker systems, and to good effect, and has also bettered many other well reviewed amps (T amps included) at or above it's price range. As Gary discovered and reported so well, different amps will have their particular characteristics. I think what might surprise people on Head-Fi is that if you look up some of the reviews of - for instance - the Emotiva amp, you will find similar 'sound performance' characteristics driving speakers as Gary found over his headphones. That is why when I researched the Millenia, I decided to try that amp in particular because  of how well it did, and that was with speakers. With the ability to have an amp 'see' the load it prefers (using the resistors), it makes sense that its performance with headphones will mirror what people hear with speakers. Now if someone is of the camp that all amps sound the same, then end of discussion. I won't even attempt to go there (after almost 40 years into this audio hobby.....) But, all that being said, it's understandable that you might like to try out what you have in house. Hell, maybe you'll discover a hidden jewel and won't need to go any further!
 
best
 
Aug 9, 2013 at 5:24 PM Post #590 of 3,871
Can a T amp be used with an SE headphone via a resistor box?
 
Aug 9, 2013 at 5:45 PM Post #591 of 3,871
Quote:
spurxiii said:
Can a T amp be used with an SE headphone via a resistor box?
Click to expand...

 
Without further qualification, I can safely answer, "Yes."   
 
But here is something you must consider...
 
If you intend to create an adapter that has four banana plugs at one end (for the speaker amp's terminals) and a 6.3mm TRS jack at the other end (to receive your headphone's single-ended, 6.3mm TRS plug), you should first make sure that the amplifier's speaker terminals have a shared ground.  
 
Call the amp's manufacturer and ask, examine the amp's schematic, or test continuity between the black terminals while the amp is turned off - take your pick or all of the above - you want to make sure that the two black terminals are common before you proceed.
 
Mike
 
Aug 9, 2013 at 6:04 PM Post #592 of 3,871
Quote:
smg52 said:
Flysweep....
It's certainly your call, but I am not sure how much the T amp you have will let you know what something like the Millenia will sound like (or the Odyssey amp for that matter). If you do some Googling about the Millenia, it's been used with ultra expensive speaker systems, and to good effect, and has also bettered many other well reviewed amps (T amps included) at or above it's price range. As Gary discovered and reported so well, different amps will have their particular characteristics. I think what might surprise people on Head-Fi is that if you look up some of the reviews of - for instance - the Emotiva amp, you will find similar 'sound performance' characteristics driving speakers as Gary found over his headphones. That is why when I researched the Millenia, I decided to try that amp in particular because  of how well it did, and that was with speakers. With the ability to have an amp 'see' the load it prefers (using the resistors), it makes sense that its performance with headphones will mirror what people hear with speakers. Now if someone is of the camp that all amps sound the same, then end of discussion. I won't even attempt to go there (after almost 40 years into this audio hobby.....) But, all that being said, it's understandable that you might like to try out what you have in house. Hell, maybe you'll discover a hidden jewel and won't need to go any further!
 
best
Click to expand...

 
 
Can you link some of the Millenia reviews?  I wonder if you need a resistor box with the Mad Dogs
 
Aug 9, 2013 at 6:24 PM Post #593 of 3,871
Folks:
 
Sorry to have missed a day or so here, but other life projects (visiting relatives, dogs, orchards) are interfering with my head time. 
 
@ Flysweep:  With the resistor box, the Millenia is easy to control.  Normal listening is between 8 and 10 o'clock on the dial, and the gain is pretty smooth.  Interestingly, with the Odyssey, normal listening is between 7 and 8:30, but it is a very smooth gain, so pretty easy to control -- without any resistor box.
 
I agree with SMG that your T-amp and the Millenia will likely sound different -- just like the Emotiva doesn't sound like the Cyclops.  At all.  The only cost to try the Millenia is the return shipping, and it doesn't weigh that much.  Not to be too much of a shill, but if you're already getting a resistor box from him, you might as well try the amp too...
 
@Prepro -- you need the resistor box with the Millenia to eliminate noise (drop the noise floor), not just to make it easier to control.  One of you tech experts can describe it better than I can, but by matching impedance to what the amp wants to see, and by increasing the output required to drive the phones, the noise floor drops considerably -- from intrusive hiss to not audible. 
 
Review links:
 
http://www.positive-feedback.com/Issue62/millenia.htm
http://www.positive-feedback.com/Issue67/tbi_millenia.htm
http://www.tnt-audio.com/ampli/3_mini_amps_e.html
 
Aug 9, 2013 at 6:38 PM Post #594 of 3,871
I needed the resistor box with the Paradox to make them completely silent, no gain hiss detectable with the Millenia. I would imagine the same would be so for Mad Dogs.....?
 
Just with regard to the T amp question, as far as I know when I researched it, T amps generally do not have shared grounds. The box that Jan made up for me compensated for the fact that his amp does not have shared grounds, and he was able to join the grounds together in the box as well as reduce the gain (but don't quote me on how I described this!) But his amp is not a T amp, by the way....
 
Okay, here are some links regarding the Millenia:
 
http://www.tnt-audio.com/ampli/3_mini_amps_e.html
 
Look at the end of the review of the Quad speakers, wherein he says he tried the Millenia with them:
http://www.tnt-audio.com/casse/quad_988_e.html
 
Major thread:
http://www.audiocircle.com/index.php?topic=108242.0
 
Here someone compares the Emotiva to the Dayens amp and prefers the Dayens amp......and the TNT reviewer preferred the Millenia to the Dayens. But notice how what he says about the Emotiva (with speakers) sounds similar to what some people have said about it with headphones.....
 
http://www.stereotimes.com/amp101112a.shtml
 
Okay, that should keep you busy. 
blink.gif

 
Aug 9, 2013 at 7:15 PM Post #595 of 3,871
gary in md said:
Folks:

Sorry to have missed a day or so here, but other life projects (visiting relatives, dogs, orchards) are interfering with my head time. 

@ Flysweep:  With the resistor box, the Millenia is easy to control.  Normal listening is between 8 and 10 o'clock on the dial, and the gain is pretty smooth.  Interestingly, with the Odyssey, normal listening is between 7 and 8:30, but it is a very smooth gain, so pretty easy to control -- without any resistor box.

I agree with SMG that your T-amp and the Millenia will likely sound different -- just like the Emotiva doesn't sound like the Cyclops.  At all.  The only cost to try the Millenia is the return shipping, and it doesn't weigh that much.  Not to be too much of a shill, but if you're already getting a resistor box from him, you might as well try the amp too...

@Prepro -- you need the resistor box with the Millenia to eliminate noise (drop the noise floor), not just to make it easier to control.  One of you tech experts can describe it better than I can, but by matching impedance to what the amp wants to see, and by increasing the output required to drive the phones, the noise floor drops considerably -- from intrusive hiss to not audible. 

Review links:

http://www.positive-feedback.com/Issue62/millenia.htm
http://www.positive-feedback.com/Issue67/tbi_millenia.htm
http://www.tnt-audio.com/ampli/3_mini_amps_e.html
Click to expand...


This isn't impedance matching, this is attentuation.
You have attentuated the noise by 14 dB.

Power amplifers don't work by impedance matching. They just present a voltage to a load, and the output current will be inversely proportional to the load.

A digital signal with a 75 Ohm digital cable is an example of impedance matching.
The digital signal is an extremely high frequency signal.
Impedance matching is used in digital and radio signals, for example.
 
Aug 9, 2013 at 8:52 PM Post #596 of 3,871
zilch0md said:
Without further qualification, I can safely answer, "Yes."   

But here is something you must consider...

If you intend to create an adapter that has four banana plugs at one end (for the speaker amp's terminals) and a 6.3mm TRS jack at the other end (to receive your headphone's single-ended, 6.3mm TRS plug), you should first make sure that the amplifier's speaker terminals have a shared ground.  

Call the amp's manufacturer and ask, examine the amp's schematic, or test continuity between the black terminals while the amp is turned off - take your pick or all of the above - you want to make sure that the two black terminals are common before you proceed.

Mike
Click to expand...

Thanks Mike, will try it out. Sounds like I need to borrow a meter. I am planning to try this on the Topping TP60 T class amp. I believe it's not an issue with my HE500s because they are balanced but to use them with my mad dogs via the resistor box I need to do as you said? Thanks for the great help and advice
 
Aug 9, 2013 at 10:31 PM Post #598 of 3,871
Quote:
nailbunny7 said:
My receiver is rated at 160 WPC into 8 ohms (maybe 4? I'm not sure. I have the Pioneer SX 1250). I should be ok to just make a speaker adaptor and plug my HE-6's into the speaker taps, right?
Click to expand...

You can just use the headphone out. The headphone out of vintage receiver is the same as the speaker taps, only with inline resistors to drop the power down.
 
Aug 9, 2013 at 10:51 PM Post #599 of 3,871
Quote:
nailbunny7 said:
My receiver is rated at 160 WPC into 8 ohms (maybe 4? I'm not sure. I have the Pioneer SX 1250). I should be ok to just make a speaker adaptor and plug my HE-6's into the speaker taps, right?
Click to expand...

That's a nice vintage Pioneer.  I just checked out one locally but the box was kind of beat up and the guy wanted too much for it.
 
Aug 9, 2013 at 10:54 PM Post #600 of 3,871
Quote:
koiloco said:
That's a nice vintage Pioneer.  I just checked out one locally but the box was kind of beat up and the guy wanted too much for it.
Click to expand...

Yeah, I actually got the SX 5590, not the 1250, but they're the exact same amp, but the 5590 is black. For some reason there was no 1250's to be found in Canada, but someone had the 5590, so I went with that, despite it costing a little bit more.
 
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