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Speaker amps for headphones - Page 51

post #751 of 2542

Gary,

 

While several of us are getting excited about the MG3, what's your latest on the Cyclops, now that you've had it for a while?  

 

I can handle knowing I've bought your second pick and will remain very grateful to both you and Stew (SMG52) for trailblazing it for use with headphones.

 

I'm just wondering if you've learned anything else about the Cyclops > LCD-3 that amazes you (or disappoints in some way.)  

 

Are you still using it without a resistor network?  

 

Thanks,

 

Mike


Edited by zilch0md - 8/21/13 at 5:46am
post #752 of 2542
Quote:
Originally Posted by zilch0md View Post

Thanks brunk!


Travel Rig as stored when carrying



That's the Italian-made HPRC 2400F (High Performance Resin Cases), shown here with a Touch, for scale.





It's available in black, blue, red or yellow and in different sizes.  It's waterproof (literally), bullet proof (figuratively speaking) and even has an automatic pressure equalization valve. It can be ordered with die-cut pluck foam. Just plan where you intend to put your junk before you start plucking. 

http://www.amazon.com/HPRC-2400F-Hard-Cubed-Black/dp/B004B8VLUU

http://www.plaber.com/cases.htm

Mike

What a nice case!
post #753 of 2542

Thanks Tom,

 

They did a really nice job with that design.  It's "all that" in terms of both function and cosmetics.

 

I haven't even received the MG3 yet, but I've ordered replacement foam for this case.  It's normally about $38 for new foam, but I found it for $12.  

 

Going just on the published dimensions of the MG3, I think there's room in this case for the MG3 on the right side, including a LiPo battery pack, and the impedance match, but I'm not sure I can get my Thunder AC-6 LiPo charger in there with everything else. As it is, I'll have to store the PCM-M10 in a narrower "hole," on its side, rather than face up.  I'm not going to pluck any foam until I've figured out what battery solution I'll be sticking with, though.

 

Mike

post #754 of 2542
Quote:
Originally Posted by zilch0md View Post

Thanks Tom,

They did a really nice job with that design.  It's "all that" in terms of both function and cosmetics.

I haven't even received the MG3 yet, but I've ordered replacement foam for this case.  It's normally about $38 for new foam, but I found it for $12.  

Going just on the published dimensions of the MG3, I think there's room in this case for the MG3 on the right side, including a LiPo battery pack, and the impedance match, but I'm not sure I can get my Thunder AC-6 LiPo charger in there with everything else. As it is, I'll have to store the PCM-M10 in a narrower "hole," on its side, rather than face up.  I'm not going to pluck any foam until I've figured out what battery solution I'll be sticking with, though.

Mike

You make me feel like getting one just so I could take all my gear with me when travelling. I think I got a brand new pelican case in the office somewhere with the foams still in place. Or is that a bit extreme?

Wait, this is Headfi, so it's not. $12 is cheap considering. Is that setup going to be your transportable? If so, that is one mighty rig
Edited by spurxiii - 8/21/13 at 6:14am
post #755 of 2542

Tom has seen this over on the iBasso PB2 thread (somehow it ended up over there, instead of here), but I put together a summary of what I've learned about using resistors with speaker amps for headphones at this link.  

 

It's incomplete, in that it doesn't provide schematics for single-ended vs. balanced headphone connections, nor does it address the subject of amps that have a common ground vs. those that don't.  There's probably more that could be added, but it is what it is, and I *think* it's accurate, but I would very much like to put it through the crucible of peer review, to make improvements or corrections as necessary.

 

Quote:

Tom and Nigel,

 

I barely have a grasp of this stuff myself, but I've been studying this subject quite a bit lately and can say with some certainty that the following statements are true.  (How's that for a disclaimer?) redface.gif

 

1)  Amps don't mind seeing a greater load (running uphill), but can be damaged by seeing a load that's less than that for which they are designed (running downhill).  So... you don't have to add resistance in parallel (across the + and - of each channel), for the sake of protecting an amp that's designed for the 4- or 8-Ohm load of speakers from the greater impedance (i.e. 38-Ohms) of a headphone.   For the amp's sake, it's perfectly OK to run without adding parallel resistors to a load that has a higher impedance than that which the amp expects.

 

2) Headphones, like speakers, can tolerate only so many watts peak from any given amp.  If the amp can produce more power than the headphone can handle, it's a good idea to add parallel resistors - for the sake of the headphones, not to protect the amp.  I've just read that the HE-500 has an impedance of 38 Ohms, but I can't find a specification for the number of Watts it can handle.  The Audeze LCD-2, can handle up to 13-Watts rms (where rms is typically about 70% of peak) into its 50-Ohm load.  You need to find out how many watts your HE-500 can handle into its 38-Ohm impedance.  If the amp does not exceed this rating into 38-Ohms, you don't need to add parallel resistors for the sake of protecting the headphones.

 

3) How do you translate a power rating into 4- or 8-Ohms into that for a higher impedance (i.e. 38-Ohms)?  For most amps, the relationship between power out and impedance of the load is not linear, but we can get in the ballpark by using an inverse proportion.  The TP60 is rated at 80 Watts (rms) into 4-Ohms, but the HE-500 presents a 38-Ohm load.

 

Power Rating of Amp * Expected Impedance / Actual Impedance = Watts into Actual Impedance (approximate)

 

80 Watts *  4-Ohms / 38-Ohms =  8.42 Watts (into 38-Ohms)

 

So, if the HE-500 can handle 8.5 Watts into 38-Ohms, there's no need to add parallel resistors for the sake of protecting the headphones, but you may want to do so for the sake of tailoring the sound, because the amp might actually sound better, or at least different, by adding parallel resistors (or for that matter, by adding series resistors). More on that in the next points...

 

4)  Keeping all of the above in mind, even if you don't need parallel resistors to protect the headphone from excessive power, you can use parallel resistors to tailor the sound.  Adding parallel resistors will make the amp sound more aggressive or sharp, less muddy or fuzzy, generally speaking. The parallel resistance should be 1/10th to 1 times the impedance of the headphones - to decrease the effective output impedance. The lower the value of the parallel resistors, the harder the amp has to work to deliver the same SPL at the headphones.  So when you add parallel resistors, SPL at the headphones will increase.  It may seem counter-intuitive, but you're allowing the amp to see less total impedance, not more (just as when switching in two pairs of 8-Ohm speakers instead of one pair, on an amp that offers the ability to drive two pairs simultaneously, presents a 4-Ohm load to the amp, not a 16-Ohm load.)  A lower value of parallel resistance gets closer to being as if there's no parallel resistor. (Duh!)  Increasing the value of the parallel resistor decreases the effective output impedance, but don't bother going any higher than the impedance of the headphones.

 

5) And now let's talk about series resistance...  If you want your amp to sound less aggressive or sharp, more relaxed, you can add series resistors to the + side of each channel - to increase the effective output impedanceThe series resistance should be 1 to 3 times the impedance of the headphones. Once a series resistor hits a value that's 3 times the headphone driver impedance, you've done all the good you're going to do in terms of reducing an aggressive sound by increasing output impedance.  Increasing the series resistance to values higher than three times the headphone impedance will only make things worse, with insufficient damping factor making things muddy.  But there's more...

 

6) Understand that with dynamic headphones, when adding series resistors, you will also be changing the frequency response, because impedance is not flat across the frequency spectrum with dynamic headphones.  With planars, which have a purely resistive impedance, their impedance is flat across the frequency spectrum, and thus, you will not get a shift in frequency response by adding series resistors.

 

Wow... I wrote a book - a  book that's completely off-topic for this thread. Sorry!

 

biggrin.gif

 

Mike

post #756 of 2542
I believe Nigel in the PB2 thread suggested I used resistors when I wasn't planning to in case I fry my HE500s. Nigel had the same TP60 speaker amp as me. It turns out Mike answered my question and I really didn't need resistors to protect the cans from the amp. My DAC is set at low gain and volume at 12 o'clock, the amp is the same 12 o'clock. The volume is as loud as my ears can take care at this level but I don't think there's any issues with frying my headphones. I need to read more on Mike's motes before I start playing around with resistors. For now I'm extremely happy
post #757 of 2542

FWIW, I used to have the Topping Tp60, he-500, he-6 and basically the same dac (the older Nfb 12). I don't think you can really damage the He-500 or He-6 with the Topping, unless you have a very hot source, and leave the volume at max.

 

About the resistors, no change with or without parallel resistors (10 ohm) with the Topping. Same goes for several vintage ss amps. As a result, I still have a few extra pairs of resistors in my drawer tongue.gif

post #758 of 2542

I'm pleased to hear of someone else who's happy with direct connection to their speaker taps.  On the Emotiva a-100 Mini-X thread, there was a period of herd mentality it seems to slap on some resistors, not really knowing why or how to go about it.  (I mean no disrespect intended to anyone, especially to those who are now enjoying a difference in sound quality.)

 

But, the more I tried to understand just exactly how I should go about it, the less evidence I could find for doing so.  And thus, I've yet to hear the Emotiva Mini-X with resistors.  redface.gif

 

I have, however, ordered Jan Plummer's impedance matching box, going on Gary's experience with the MG3.  I couldn't possibly order the MG3 without it, right?  biggrin.gif   

 

Gary's ability to describe what he hears is not only edifying for what we can learn by paying close attention to his words, but it reveals that he really has a discerning ear and great credibility - as can only come from all those years in HiFi.  It doesn't surprise me that Stew (SMG52) has a similar background (decades of experience) to independently find his way to using the MG3 with his Paradox headphones - and he, too, has found Jan's impedance match to make a world of difference.

 

The best thing about Jan's impedance match, is that we've got a world-class amp designer tailoring his amp to the impedance of our headphones - with no thinking (or soldering) required on our part. So much for my dissertation on how to select resistors!

 

Mike

post #759 of 2542
Quote:
Originally Posted by zilch0md View Post

I'm pleased to hear of someone else who's happy with direct connection to their speaker taps.  On the Emotiva a-100 Mini-X thread, there was a period of herd mentality it seems to slap on some resistors, not really knowing why or how to go about it.  (I mean no disrespect intended to anyone, especially to those who are now enjoying a difference in sound quality.)

 

But, the more I tried to understand just exactly how I should go about it, the less evidence I could find for doing so.  And thus, I've yet to hear the Emotiva Mini-X with resistors.  redface.gif

 

I have, however, ordered Jan Plummer's impedance matching box, going on Gary's experience with the MG3.  I couldn't possibly order the MG3 without it, right?  biggrin.gif   

 

Gary's ability to describe what he hears is not only edifying for what we can learn by paying close attention to his words, but it reveals that he really has a discerning ear and great credibility - as can only come from all those years in HiFi.  It doesn't surprise me that Stew (SMG52) has a similar background (decades of experience) to independently find his way to using the MG3 with his Paradox headphones - and he, too, has found Jan's impedance match to make a world of difference.

 

The best thing about Jan's impedance match, is that we've got a world-class amp designer tailoring his amp to the impedance of our headphones - with no thinking (or soldering) required on our part. So much for my dissertation on how to select resistors!

 

Mike

I just wanted to clarify something: when I first used the Millenia, I hooked up resistors in order to bridge the negative terminals so that I could use my Paradox which are wired in single-ended mode. I followed Jan's instructions for doing this. It sounded great, but there was too much background hiss (gain) so that is what prompted Jan to come up with a box for me which both took care of the grounding issue and the background hiss issue. I personally didn't go the resistor route because I thought it would sound better. It was to eliminate that hiss (so, yes, of course without the hiss it sounds 'better'). But I don't know if I would advise someone to use resistors with the Millenia if their headphones were balanced, and so inefficient that maybe they would not have any hiss. If I understood an email of his correctly from some time ago, if I were to try something like the HE-6 headphones with the Millenia, and with balanced cabling, he thought I might not need resistors.....

post #760 of 2542

Another point about this background hiss issue. The first speaker amp I tried with my Paradox was the Musical Fidelity A1 (class A) integrated amp I had been using (the more current version). The amp had shared grounds, so with an extension headphone cable that was made for me by Bryan at Zynsonix, which had left and right cables for direct connection to the amp, I was able to hook up the headphones directly to the amps speaker terminals. That amp is also rated at around 30 watts/channel. It was a revelation, sound-wise. But, there was some background hiss. At first I was so taken by how the headphones sounded, I didn't mind the hiss (which when music was playing, was unobtrusive), but, being as fussy as I am, that wouldn't due in the long run. In the meantime, I had read  about the Millenia amp and that tweaked my interest, and even before I ordered the amp to try it out, Jan was very helpful in sorting out how I could make my single ended headphones work with the amp. The Millenia quickly replaced my Musical Fidelity amp for use with my headphones, it was that much better sonically. I was intrigued by the fact that Gary doesn't need any resistors with his Odyssey amp, which is of course a much higher wattage amp then the Millenia (although his range for volume appears somewhat constrained). In communicating with a more technically savvy audiophile friend of mine, he says there are a number of factors that might be the cause of having background hiss in this situation. In any case, it's been good to have the amps designer available to alleviate the issue! 

post #761 of 2542
Quote:
Originally Posted by SMG52 View Post

But I don't know if I would advise someone to use resistors with the Millenia if their headphones were balanced, and so inefficient that maybe they would not have any hiss. If I understood an email of his correctly from some time ago, if I were to try something like the HE-6 headphones with the Millenia, and with balanced cabling, he thought I might not need resistors.....

 

In my setup the hiss is still present when connecting the HE-6s to the Millenia with no resistor network. I had to place the box in between to get rid of the hiss.

post #762 of 2542
Quote:
Originally Posted by victorcc View Post

 

In my setup the hiss is still present when connecting the HE-6s to the Millenia with no resistor network. I had to place the box in between to get rid of the hiss.

Interesting. Thanks for that clarification. I may have misunderstood Jan's email.

 

Sorry if you mentioned it elsewhere, but how do you like the combination of the Millenia with HE-6?

post #763 of 2542

Thanks Stew.  I will have the MG3 for about a week before the resistor box arrives, and I will be using balanced cables to my LCD-2 rev.1.  I'll let you know if I hear any hiss.

post #764 of 2542
Quote:
Originally Posted by zilch0md View Post

Thanks Stew.  I will have the MG3 for about a week before the resistor box arrives, and I will be using balanced cables to my LCD-2 rev.1.  I'll let you know if I hear any hiss.

From Gary's experience, as well as that of victorcc above, (as well as mine), seems likely there will be a background hiss. But, you should get to enjoy the amp with music playing, I would assume, before the resistor box arrives.  

post #765 of 2542
Quote:
Originally Posted by zilch0md View Post

Gary,

 

While several of us are getting excited about the MG3, what's your latest on the Cyclops, now that you've had it for a while?  

 

I can handle knowing I've bought your second pick and will remain very grateful to both you and Stew (SMG52) for trailblazing it for use with headphones.

 

I'm just wondering if you've learned anything else about the Cyclops > LCD-3 that amazes you (or disappoints in some way.)  

 

Are you still using it without a resistor network?  

 

Thanks,

 

Mike


Mike:

 

What I've learned recently about the Cyclops is that it sounds great with lower-quality transfers as well.  My nephew gave me a lot of low-bit-rate MP3s, and they sound incredibly good with the Cyclops.  Not as good as FLACs, but waaaay better than they did using my Adcom pre-amp.  I also tried listening to some crappy pop recordings (Neon Trees) and even they sounded good. 

 

And I am not using a resistor box (or any other resistors) with this amp.  There is absolutely no need for it. 

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