[roguegeek]

  I need help understanding something. I have certain headphones and IEM that sound like absolute crap with the Magni, but other that are equally efficient that sound fine. A Porta Pro sounds fine through it. A PX 100-II or XBA-3 sounds like crap. I know this has to do with a low impedance headphone not being able to work with a high output impedance amp. Bottom line, I don't get it. Is there something someone can point me to that will help me understand this concept or can someone give me a simplified answer? Also, what's the math that needs to be done in order to know if a certain can will work with a certain amp?

Ok. I think I may have it. Headphones work best with an amp when the amp output impedance is less than 1/8th the headphone impedance.
 
My Porta Pro has an impedance of 60 Ohms. 60 / 8 = 7.5
0.1 Ohms output impedance of the Magni is less than 7.5 Ohms, so my Porta Pro should sound just fine on a Magni, and it does.
 
My XBA-3 has an impedance of 12 Ohms. 12 / 8 = 1.5
0.1 Ohms output impedance of the Magni is less than 1.5 Ohms, so my XBA-3 should sound just fine on a Magni, yet it doesn't.
 
My PX 100-II has an impedance of 32 Ohms. 32 / 8 = 4
0.1 Ohms output impedance of the Magni is less than 4 Ohms, so my PX 100-II should sound just fine on a Magni, yet it doesn't.
 
What am I doing wrong here?

 

[PXSS]

There's more to it that that, I don't know the details though...

 

[MrMateoHead]

  Ok. I think I may have it. Headphones work best with an amp when the amp output impedance is less than 1/8th the headphone impedance.
 
My Porta Pro has an impedance of 60 Ohms. 60 / 8 = 7.5
0.1 Ohms output impedance of the Magni is less than 7.5 Ohms, so my Porta Pro should sound just fine on a Magni, and it does.
 
My XBA-3 has an impedance of 12 Ohms. 12 / 8 = 1.5
0.1 Ohms output impedance of the Magni is less than 1.5 Ohms, so my XBA-3 should sound just fine on a Magni, yet it doesn't.
 
My PX 100-II has an impedance of 32 Ohms. 32 / 8 = 4
0.1 Ohms output impedance of the Magni is less than 4 Ohms, so my PX 100-II should sound just fine on a Magni, yet it doesn't.
 
What am I doing wrong here?

I can venture a guess. The "rated" output impedance could be wrong, that is, your lower impedance cans suggest that it could actually be just outside the optimal range.
 
Also, the rated headphone impedance isn't always perfect, that is, with dynamics, you have peaks and valleys somewhere in the response. The impedance could be dipping lower than advertised, and messing up overall damping.
 
But I am guessing. What exactly is wrong with the sound of the two that aren't working well with the amp?

 

[UmustBKidn]

  Ok. I think I may have it. Headphones work best with an amp when the amp output impedance is less than 1/8th the headphone impedance.
 
My Porta Pro has an impedance of 60 Ohms. 60 / 8 = 7.5
0.1 Ohms output impedance of the Magni is less than 7.5 Ohms, so my Porta Pro should sound just fine on a Magni, and it does.
 
My XBA-3 has an impedance of 12 Ohms. 12 / 8 = 1.5
0.1 Ohms output impedance of the Magni is less than 1.5 Ohms, so my XBA-3 should sound just fine on a Magni, yet it doesn't.
 
My PX 100-II has an impedance of 32 Ohms. 32 / 8 = 4
0.1 Ohms output impedance of the Magni is less than 4 Ohms, so my PX 100-II should sound just fine on a Magni, yet it doesn't.
 
What am I doing wrong here?

 
The answer to your question may reside in this article on Wikipedia about output impedance.
 
The IEM's are 12 ohms, which is quite low to be used with an amp. Any transducer with an impedance that low really doesn't need to use an amp - it can be run right from the iPod, computer, phone, etc. Kind of like trying to take a sip of water from a fire hydrant.
 
I would guess that the damping factor of the PX 100's just isn't working with the Magni. Those cans are meant to be portables, which would imply to me that they're being used directly out of the ipod, phone, etc. Again, probably just over powering them with a Magni. I don't think there's any magic to that.

 

[roguegeek]

Alright. So it's not as simple as the 8:1 ratio thing. Funny thing is everything sounds fine on an E10 and its output impedance is <0.3 Ohms.

 

[PXSS]

It also has to do with how much power you're putting through the headphones, some headphones also need a higher current running through them while others depend on voltage. It really isn't that simple...

 

[NoSo]

Just got these. I noticed that when my headphones are plugged in (Q701), and I turn on the amp, it makes a pop noise, mostly on the left driver.
 
After further searching, I believe this is known as the protective relay? What exactly does the PR do to generate a popping/thumping sound when turned on? I'm a little worried that it my damage my drivers.
 
I've read that you should turn on the amp, then plug in your headphones. Then when you turn it off, plug out your headphones, and then turn it off.

 

[Defiant00]

  Just got these. I noticed that when my headphones are plugged in (Q701), and I turn on the amp, it makes a pop noise, mostly on the left driver.
 
After further searching, I believe this is known as the protective relay? What exactly does the PR do to generate a popping/thumping sound when turned on? I'm a little worried that it my damage my drivers.
 
I've read that you should turn on the amp, then plug in your headphones. Then when you turn it off, plug out your headphones, and then turn it off.

 
A small pop/thump is completely fine. The relay mutes the signal for the first 5-10 seconds while the amp is powering on so that it doesn't send anything louder than that pop through your headphones. It then stops muting, so you get a small pop.

With that said, I typically turn my amp on first and then plug in my cans. I haven't had any problems with damage or anything, but I figure there's never any harm in being too careful.

 

[SonyMDRer]

Sorry I got two stupid questions.
 
1) Should I leave the magni/modi combo on all the time? Or is that bad for the amp?
What about the USB on the modi? Should I unplug it after every use?
 
2) I noticed at really low volumes, I do not get any volume on my left side of the headphone. Is this normal?
 
Thanks!

 

[Honkytime]

  Sorry I got two stupid questions.
 
1) Should I leave the magni/modi combo on all the time? Or is that bad for the amp?
What about the USB on the modi? Should I unplug it after every use?
 
2) I noticed at really low volumes, I do not get any volume on my left side of the headphone. Is this normal?
 
Thanks!

(1) There are no stupid questions only stupid answers.
 
(2) I try to turn my equipment off when i'm not using it. (like when you sleeping or at work.)
 
(3) yes the magni has a channel imbalance at low volume that's perfectly normal.

 

[Defiant00]

  Sorry I got two stupid questions.
 
1) Should I leave the magni/modi combo on all the time? Or is that bad for the amp?
What about the USB on the modi? Should I unplug it after every use?
 
2) I noticed at really low volumes, I do not get any volume on my left side of the headphone. Is this normal?
 
Thanks!

 
1) I'd recommend turning the Magni off and leaving the Modi alone.
 
2) Yup, that's normal.

 

[nedaroth]

I want to use the magni/modi combo with my PC, i just looked at a pic of the pair stacked with the RCA cables running from the magni to the modi, do i just run the usb then from the mobi to my PC, is it just that simple?
 
Thanks for any help.

 

[jgreen16]

I want to use the magni/modi combo with my PC, i just looked at a pic of the pair stacked with the RCA cables running from the magni to the modi, do i just run the usb then from the mobi to my PC, is it just that simple?


 


Thanks for any help.

 


There is also a wall wart that connects to the Magni, but yeah, it's that simple.

 

[nedaroth]

 

  I want to use the magni/modi combo with my PC, i just looked at a pic of the pair stacked with the RCA cables running from the magni to the modi, do i just run the usb then from the mobi to my PC, is it just that simple?
   
  Thanks for any help.

 


There is also a wall wart that connects to the Magni, but yeah, it's that simple.

Thanks for your reply J

 

[nedaroth]

fixed thanks