Two headphones at once? An utterly natural crossfeed effect
Jan 26, 2013 at 4:11 PM Thread Starter Post #1 of 19

Nirmalanow

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I happen to love trying out weird and different things, as evidenced by my setup a few years back which was a bit unusual to say the least. It included an Echofone which is a kind of super-tweeter for headphones as I described here: http://www.head-fi.org/t/278315/echofone-a-super-tweeter-for-headphone-users-or-the-hearing-impaired
 
A long time ago, I sold the Echofone as I found I did not need it with my MD5000 headphones. Now I am instead enjoying the full body and richness of the sound of my HD650s, but as I was sitting listening I suddenly had the desire to add the Echofone back to my system. The HD650s do not quite have the clarity and detail of the MD5000s and of course I want it all. But I am not about to buy another Echofone, expecially since it is not portable and I do not like to be limited to sitting near AC power.
 
Then I had a crazy idea. I use a DX100 as source with the line out feeding a Continental amp. But the DX100 of course also has headphone ouputs that function at the same time as the line out. I wondered if I put another set of headphones on my temples just like the Echofone, whether I could recreate the effect of the Echofone. It was as easy as grabbing my Sony MDR-XB500 headphones, plugging them in and putting them on top of my head with the pads resting on my temples instead of around my ears. This still transmits sound that I can hear, although just like the Echofone, the sound through my temples of the Sony's by themselves sounds like a bad telephone speaker. But I was also wearing the HD650s plugged into the Continental, and when I turned those up also, the sound of course filled in.
 
And it filled in very nicely. It was not like night and day, but there was a slight but enjoyable added depth and richness to the sound. Another strange thing is I liked it better with the left earpiece of the Sony on my right temple. I think that adds a bit more "crossfeed" to the effect by sending more left channel sound to my right ear and vice versa. So there was also more depth to the soundstage with both headphones on my head. The sound also shifts a little bit further forward and so is slightly more in front of me. One surprise is that I did not notice that much added detail which is what I was initially looking for, but I did discover something nice instead. Maybe a bit more detail, but not a lot. I am not sure the overall improvement is worth the bother, since it is only a slight upgrade in sound. I will have to play with it some more.
 
One drawback is that you look like a total goofball with two headphones on your head. Fortunately there is no one here but my wife, and she is used to me :)
 
Another concern is that in order to hear the effect I had to crank the DX100 volume all of the way which meant the Sony's were blasting sound at my temples (and they are very efficient headphones and the DX is very powerful). I did not hear it as very loud at all since they were not near my ears, but I wonder if the life of the Sony's would be dramatically shortened if I did this very often. They are not a huge investment so I am probably going to keep experimenting. And maybe there are some other headphones out there that would be more efficient at delivering the sound into the bones in my temples. The Sonys have big thick cusions that hold the speakers a bit away from my skin. Also they are bass heavy headphones which is kind of a waste since I can't really hear the bass through my temples.Anybody have a suggestion for some on the ear headphones that are extremely bright with a lot of treble? i figure on the ear headphones would bring the speaker diaphragms closer to my skin than the big around the ear cushions of the Sony's.
 
Have I lost my mind, or have I found my true calling in life as a mad inventor?
 
Edit added: It seems I can get by with a little less than full volume feeding the Sony's so maybe they will last longer than a few more hours of use
rolleyes.gif
I have the DX volume set at about 220 and then make up the difference with the volume control on the Continental for the sound feeding my HD650. Probably not good to use the DX100 at that level for long either.
 
Edit added: I found using Koss KSC75's which are on ear clip on headphones allows me to use less volume as described further down in this thread. However, I do not use them against my skin as I get more sound just hanging them off of a headband right in front of my HD650s.
 
Jan 26, 2013 at 5:25 PM Post #3 of 19
if it works for you, then it works. At one point I used headphones in conjunction with my subwoofer. I got to enjoy the intimacy of headphones and the body shaking bass at the same time.

Sent from my SGH-I777 using Tapatalk 2
 
Jan 26, 2013 at 7:00 PM Post #5 of 19
Quote:
if it works for you, then it works. At one point I used headphones in conjunction with my subwoofer. I got to enjoy the intimacy of headphones and the body shaking bass at the same time.

Sent from my SGH-I777 using Tapatalk 2


I also have experimented with using a subwoofer and headphones at the same time. Back when I had K1000s, I would even combine them with speakers positioned right behind me. It sometimes created an eerily real sound.
 
Jan 26, 2013 at 9:25 PM Post #6 of 19
I spent a little more time with my new trick and it seems that the main effect is possibly due to a crossfeed. I notice a sense of the music coming into focus with the second headphones on with the right and left reversed. Each instrument seems to become more specifically located in space. Overall, it seems to allow my mind to relax since the music sounds more natural to me. It is a subtle effect, but it just sounds more like the way live music would sound in the room, or at least maybe the way well placed speakers would sound. Without the second headphone on my forehead the sound splits more into two separate sounds coming in both ears, and it is as if my mind then has to sort that unnatural effect back into music.
 
Also the tone seems to fill in and be more full bodied. Without the Sony headphones, some female vocalists sound kind of breathy. When I add them back to my temples, the female voices sound more full and less breathy. It is a very nice effect.
 
Jan 27, 2013 at 10:04 AM Post #7 of 19
I just ordered a pair of Koss KSC75 on the ear clip on type headphones for about $15 which should be a little easier to use and also should place the speakers closer to the skin on my temples. I will hold them in place with a headband which is the same way the Echofone is used. I will report back on any additional observations after they arrive. They are a cheap way to continue my experiment.
 
Jan 28, 2013 at 9:04 PM Post #8 of 19
I changed the name of this thread to mention the crossfeed effect I am hearing. It is hard to listen now without the second pair of headphones as the sound seems to move further into my head and also becomes a little disjointed. When I add the second headphones, the sound settles a little further forward and sounds like a well placed set of speakers. It is like the two headphones disappear and I am just hearing music instead.
 
I also still hear the filling in of the tone. It is like some air and space is removed from each note, but this is a good thing as it makes each instrument sound very clear and full as it's own sound. Without the second headphones, the sound kind of splits which creates more air and space, but somehow lightens the tone and is less natural sounding to me. This effect is most noticeable on female voices, but it is there on all of the mid range tones, especially when an insturment or voice is placed in the center of the soundstage.
 
Again, all of this is with the Sony headphones resting on the temples of my forehead with the left phone on my right temple and the right phone on my left temple. I am looking forward to trying the Koss on-ear headphones as i am guessing that I will be able to get a more definite effect using headphones with the diaphragm closer to my skin. The Sony's have too much padding in their cusion. However, it is pretty interesting that I hear such a definite effect because when I turn down the main Hd650 phones all of the way, there is very little sound reaching my ears from the Sony's by themselves. Again, I am hoping the Koss phones are better than the Sony's at delivering sound through my facial bones to the ears similar to how the Echofone worked.
 
Jan 29, 2013 at 10:35 PM Post #9 of 19
I got the KSC75 headphones and after playing around some, I found it best to just hang the Koss headphones off of a headband right in front of the HD650s, again with the right and left reversed to get a crossfeed effect. It turns out that the having the drivers closer to my skin did not transmit more sound, and if I just hang them like tiny little speakers outside the open HD650s, there is just enough sound that gets in to my ears. When I turn down the main headphones completely, there is just a little sound that is mostly higher frequencies. Just like what you hear if you hold your headphones a few inches from your ears. The bass diappears. However, it seems like the treble is enough to create the crossfeed effect.
 
My latest take is that the effect is incredibly subtle but still enjoyable. I tried to equal the sound levels by turning down the Hd650's ever so little after turning up the second headphones, and it is hard to pin down exactly what I am hearing. In any case, I do feel like I relax just that little bit more into the music with this slight crossfeed happening. And unlike most of the other crossfeed effects I have tried, this one seems natural and does not degrade the sound. If anything it adds more body to the tone, but that might also be due to the very slight increase in volume when I turn up the Koss headphones, as I may not be turning down the HD650's enough to equal out the levels.
 
I keep going back to using the crossfeed as even if I can't put it into words or consciously pin down what is happening because it is so subtle, I still just feel like the music takes on a more natural and organic quality that I like. I have some T1 headphones on their way to me and I will try it with them also to see how it works with some higher priced open cans.
 
Jan 31, 2013 at 10:02 AM Post #10 of 19
I also find the second set of headphones fills in the center of the soundstage. It is like one continuous wall of music instead of two areas of sound with a bit of a donut hole in the middle.
 
Jan 31, 2013 at 9:42 PM Post #11 of 19
Life does not always protect us from our own stupidity.
 
To get the crossfeed effect I had to run the second headphones at nearly full volume (around 220-230 on high gain) which was causing some distortion. I knew that it would likely damage the headphones but did not care since I only paid $15 and wanted to see if there was anything to the experiment. However, I did not realize that it would also damage the amp in my new (to me) DX100. Now when I play my HD650s through the headphone out on my DX100 I get some very noticeable distortion at moderately high volume.
 
So I am afriad I know the answer, but for those who know more (obviously much more), is it true that I probably damaged the amp in the DX100 by running it at levels that were causing distortion in the cheap headphones I had plugged in? I probably ran it this way for well over two hours. So basically I am asking if playing at levels that are clipping and distorting will damage an amp as well as the speakers or headphones hooked up to that amp?
 
Fortunately, it has not affected the line out signal, so I may just be using the DX100 to feed another amp for the rest of my life
frown.gif
.  And there goes it's resale value unless I send it in for repairs to iBasso.
 
Live and never learn is my motto, but this may have been an especially expensive lesson.
 
EDIT ADDED: Great news. The problem all along was with the aftermarket cable I was using with my HD650s. Fortunately, I just got a set of Beyer T1s and when I hooked up these 600 ohm headphones to the DX100 there was no distortion. So I went back to the HD650 and there was the distortion again. I pulled out my stock cable and hooked it up.....no distortion. There must be a loose connection in the new cable. Funny how it happened right after my experiment with using two headphones, and I was sure it was due to that. but it was just a coincidence that the connection in the new cable came loose right after that.

 And with the Koss KSC75 headphones, I do not need to play them as loud as the Sony's so I will not be pushing my luck by overdriving the headphones and the amp anymore.
 
Feb 1, 2013 at 9:26 AM Post #13 of 19
IEMs often block a lot of sound....but if you use a pair with very little isolation, it might work. However, I read somewhere that it is not good to mix low impedance and high impedance cans on the same amp, so definitely try it with two amps. And at least that approach would probably not require blasting either headphone at high levels.
 
I used to listen to my K1000s with a pair of bookshelf speakers placed right behind my head. It was finicky to get the levels right, but there were times when the sound was spookily real. I would sometimes jump at a sound on the recording thinking someone was in the room with me.
 
Feb 1, 2013 at 9:27 AM Post #14 of 19
Quote:
Very creative! What about the idea of mixing IEM with Over Ear cans? Anyone try anything wacky?


I might just have to try this later today and report back. I will use my REOs with earpieces that do not seal very well. the full size cans would only have to be used at very low volumes as they are just there for the crossfeed.
 
Feb 1, 2013 at 1:06 PM Post #15 of 19
It did not work very well using IEMs. If i used small eartips on the REOs, and let them play at low volume while wearing the HD650s at higher volume, the sound was a muddled mess. And if I used larger eratips and got a good seal with the REOs at full volume, then adding on the HD650s there was more bass, but again it was muddied. It seems the effect works with the second headphones hanging in front of a pair of full sized open headphones.
 
I will still try it with my new T1s but I kind of doubt it will be an improvement since they have a very nice soundstage already compared to my HD650s.
 

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