[Manel]

Yeah, I know that, but I'm talking about the relation between the output impedance of the sound card and the nominal impedance of the headphones. I read somewhere there's a rule that says the output impedance of the Amp should be less than 1/8th the headphone impedance. Otherwise, there can be sound distortion, and the headphones may sound differently than they were originally tuned. That's what I am referring to.
 
As far as I know, some russian hardware reviews site measured the output impedance of the ZxR as being around 40 ohm. Even STX has 10 ohm output impedance. Maybe I should pick this up instead to drive the 598s.

 

[NoOneLt]

Hi again, if to dig into it deeper, STX amp TI TPA6120A2, ZxR - TI TPA6120 as written in their page, but at TI page a cannot find TPA6120, only A2 so i believe ZxR have same amp as STX. Some forums gives the same information.
 
Here is the datasheet for amp: http://www.ti.com/product/tpa6120a2
 
I am really not good in physics, and i can misunderstood something, but in datasheet there is "Output resistance Open Loop 13 Ω". Also ZxR can switch between <300 and 300-600 Ohm modes, so maybe measuring in second mode would give 40. And believe STX should have same option as amp hardware is the same.
 
And if You would like to keep up with 1:8 rule then You should consider ~80Ohm headphones, but i believe You will be totally fine with 598, i don't think we could notice audible difference if there any in this case  

 

[germanium]

  Hi again, if to dig into it deeper, STX amp TI TPA6120A2, ZxR - TI TPA6120 as written in their page, but at TI page a cannot find TPA6120, only A2 so i believe ZxR have same amp as STX. Some forums gives the same information.
 
Here is the datasheet for amp: http://www.ti.com/product/tpa6120a2
 
I am really not good in physics, and i can misunderstood something, but in datasheet there is "Output resistance Open Loop 13 Ω". Also ZxR can switch between <300 and 300-600 Ohm modes, so maybe measuring in second mode would give 40. And believe STX should have same option as amp hardware is the same.
 
And if You would like to keep up with 1:8 rule then You should consider ~80Ohm headphones, but i believe You will be totally fine with 598, i don't think we could notice audible difference if there any in this case  

Open loop refers to running without overall loop feedback which nobody would dare do with these amps. Output impedance is much lower with overall loop feedback, however 10 ohms resistor needs to be added to maintain stability of the amp & protect against shorts so you will almost always see at least 10ohms output impedance wherever these amp chips are used. This is not the output impedance of the amp itself though which is much lower.

 

[NoOneLt]

 
Open loop refers to running without overall loop feedback which nobody would dare do with these amps. Output impedance is much lower with overall loop feedback, however 10 ohms resistor needs to be added to maintain stability of the amp & protect against shorts so you will almost always see at least 10ohms output impedance wherever these amp chips are used. This is not the output impedance of the amp itself though which is much lower.

 
Hi, @germanium, maybe You can clear things out a bit about impedance of ZxR and SQ @manel is worried about, i am also confused, should it be the thing to worry about, ant that 1:8 rule? 

 

[germanium]

Hi, @germanium
, maybe You can clear things out a bit about impedance of ZxR and SQ @manel is worried about, i am also confused, should it be the thing to worry about, ant that 1:8 rule? 

While output impedance can be an issue with some phones some phones have sufficient physical damping attached to the back side of the driver that output impedance of th amp is of very little consequence.

I'm not one of those people who say you must always have zero output impedance as it simply is not true. Back in the earlier days of my hobby I noticed that many receivers had very high output impedances of 400-500ohm & many of the phones sounded fine even at that high output impedance. It's not a one size fits all type situation as some people here assume needs to be the case. 10 ohms is sufficiently low output impedance for many though not all phones.

Note I have not measured the output impedance of the headphone amp nor have I tried to trace the output circuit. You can not simply measure it by put in an ohm meter on the output with the amp on as D.C. offset will throw off your measurement.

 

[sicbud]

Hello Everyone,
 
First of all, I'm new to this whole audiophile thing (and god is it expensive and confusing).  I've read almost this entire thread (wow, what a read).  I'm looking at the best possible solution for music and games (but don't want to spend an arm and a leg).  
 
I'm currently using a pair of HE-400's (35 Ohm impedance), and from what I gather reading this thread, the best solution would be to purchase a NFB-11.32/NFB-15.32 and a regular SBZ.  I'd then want to use the optical port on the SBZ to the optical-in port on the NFB.  Is this correct?
 
Does anyone know the difference between the NFB-11.32 and the NFB-15.32?  The audio-gd website is kinda confusing in the way it is setup and the only difference I saw was that one has a Sabre ES9018 chip while the other one uses dual WM8741 Chips, but I honestly don't know the difference (like I said I a noob).
 
Would I still be able to use the USB on the NFB devices (when I'm at a different computer that doesn't have the SBZ)?  I know I wouldn't get surround or anything, but someone earlier said that there is a big potential for interference or something.
 
The audio-gd website does list an upgrade "There are two TCXO can for upgrade, one is the 12MHz for the USB interface, another is 80MHz for the ES9018"  I have no idea what that means, or what it would help, but is the upgrade worth it?
 
I'm coming from an ASUS Xonar STX, but it won't be in the new computer due to it being PCI and the fact that I don't really like the drivers and the gaming features of the card.
 
Any insight is appreciated.
 
Thanks!

 

[SEALBoy]

  Hello Everyone,
 
First of all, I'm new to this whole audiophile thing (and god is it expensive and confusing).  I've read almost this entire thread (wow, what a read).  I'm looking at the best possible solution for music and games (but don't want to spend an arm and a leg).  
 
I'm currently using a pair of HE-400's (35 Ohm impedance), and from what I gather reading this thread, the best solution would be to purchase a NFB-11.32/NFB-15.32 and a regular SBZ.  I'd then want to use the optical port on the SBZ to the optical-in port on the NFB.  Is this correct?
 
Does anyone know the difference between the NFB-11.32 and the NFB-15.32?  The audio-gd website is kinda confusing in the way it is setup and the only difference I saw was that one has a Sabre ES9018 chip while the other one uses dual WM8741 Chips, but I honestly don't know the difference (like I said I a noob).
 
Would I still be able to use the USB on the NFB devices (when I'm at a different computer that doesn't have the SBZ)?  I know I wouldn't get surround or anything, but someone earlier said that there is a big potential for interference or something.
 
The audio-gd website does list an upgrade "There are two TCXO can for upgrade, one is the 12MHz for the USB interface, another is 80MHz for the ES9018"  I have no idea what that means, or what it would help, but is the upgrade worth it?
 
I'm coming from an ASUS Xonar STX, but it won't be in the new computer due to it being PCI and the fact that I don't really like the drivers and the gaming features of the card.
 
Any insight is appreciated.
 
Thanks!

I know this is an audiophile forums, but honestly, you don't need to buy an external DAC/amp.
 
I also have HE-400's that I use with a Sound Blaster Z for music and games. It sounds great. The SBZ does virtual surround for gaming which actually works pretty well with the HE-400.
 
The amp on the SBZ is more than capable of driving the HE-400.
 
If you have $300 to spend on a DAC/amp when you already have an SBZ, invest those in better headphones. Your greatest leap in quality will be in stepping up to an HE-500 or similar headphones, not a DAC/amp.

 

[sicbud]

Thanks for your reply.  One of the reasons for the DAC/amp was so that I could use it on other computers and would also be able to use it with consoles.  I could invest in a new pair of headphones, but I just purchased the HE-400's, seriously, like 2 weeks ago. Lol.

 

[SaLX]

I'm currently using a pair of HE-400's (35 Ohm impedance), and from what I gather reading this thread, the best solution would be to purchase a NFB-11.32/NFB-15.32 and a regular SBZ.  I'd then want to use the optical port on the SBZ to the optical-in port on the NFB.  Is this correct?
 
SBZ with optical out works perfectly with the Audio_gd's.
 
Does anyone know the difference between the NFB-11.32 and the NFB-15.32?  The audio-gd website is kinda confusing in the way it is setup and the only difference I saw was that one has a Sabre ES9018 chip while the other one uses dual WM8741 Chips, but I honestly don't know the difference (like I said I a noob).
 
11.32 is for darker or warmer headphones like Sennheisers; the 15.32 for brighter and/or neutral headphones like the DT990/AKG's. Do a bit of research to see which one would suit your HE's. The difference isn't going to be huge by any means...., just by degrees.
 
Would I still be able to use the USB on the NFB devices (when I'm at a different computer that doesn't have the SBZ)?  I know I wouldn't get surround or anything, but someone earlier said that there is a big potential for interference or something.
 
yes... you can have both optical cable and USB cable attached and easily swap in the windows sound control panel / mixer. No worries on interference.
 
The audio-gd website does list an upgrade "There are two TCXO can for upgrade, one is the 12MHz for the USB interface, another is 80MHz for the ES9018"  I have no idea what that means, or what it would help, but is the upgrade worth it?
I'm coming from an ASUS Xonar STX, but it won't be in the new computer due to it being PCI and the fact that I don't really like the drivers and the gaming features of the card.
 
$40? - If you can stretch to it, then yes. They reduce jitter between the source and the receiver. Many have reported a smoother sound.

 
As Sealboy says though.. you'll probably get away with using the SBZ with it's built in amp. The HE400 doesn't need a lot of juice. Also MLE pointed out in his review that a portable amp is all you need. I'd say, in the end, just get the SBZ and see how you feel about it, then add the Audio_gd later (like me) or initially get a moar expensive ZxR and be done with it.

 

[SEALBoy]

  Thanks for your reply.  One of the reasons for the DAC/amp was so that I could use it on other computers and would also be able to use it with consoles.  I could invest in a new pair of headphones, but I just purchased the HE-400's, seriously, like 2 weeks ago. Lol.

Unless your DAC can decode Dolby Digital/DTS and create virtual surround sound, you won't get surround sound through your SBZ optical out because it simply encodes the surround sound signal and passes it through. The SBZ is effectively removed from the equation (apart from its role as an encoder), so you might be better off just getting a USB DAC/amp instead of paying for one with an optical input.

 

[SaLX]

Oh dear SeaLBoy.. you are completely wrong. You have given terrible advice there. My external DAC/Amp get's the premixed PCM signal that's been mixed by the SBZ that sends it via optical/SPDIF. What I hear is true surround, and I get to utilise fully all the aspects of the SBZ's control panel.
 
**Edit** I'd ask this on Mad Lust Envy's thread regarding consoles and external DAC's.

 

[SEALBoy]

  Oh dear SeaLBoy.. you are completely wrong. You have given terrible advice there. My external DAC/Amp get's the premixed PCM signal that's been mixed by the SBZ that sends it via optical/SPDIF. What I hear is true surround, and I get to utilise fully all the aspects of the SBZ's control panel.
 
**Edit** I'd ask this on Mad Lust Envy's thread regarding consoles and external DAC's.

Hmm, you might be right. In your case the virtual surround would be through SBX Pro Studio, not Dolby Digital/DTS.
 
However, I still stand by my initial statement that he is wasting money on a DAC with optical input. He gains very little from outputting via optical vs. just using the onboard DAC, and getting a superior USB-only DAC/amp for his other computer.

 

[sicbud]

Thanks for both of your replies.  I think I'll go with the SBZ first as you suggested, SaLX and go from there.  I realize the HE's don't require a lot of power, but I can confirm they sound a lot better with the extra gain, at least that's the case with my STX.  When I set the gain to high, the headphones come alive, and sound even better when I set it to extra high gain.
 
The other thing that worries me with just using the SBZ is that people here were complaining about issues with low impedance headphones which the HE-400's are.
 
The issue with a USB DAC/amp is that it won't work with consoles (at least as far as I know).  I realize I wouldn't be getting surround sound on that, but stereo headphones would still be better than nothing.
 
I guess the alternate would be to buy my buddies H-Wireless headset off him for $100 ($300 value) and use that for consoles.  That would work Consoles and would provide surround sound, but I can't image the quality of those headphones would be anywhere near the quality of the HE-400's.

 

[NoOneLt]

  Thanks for both of your replies.  I think I'll go with the SBZ first as you suggested, SaLX and go from there.  I realize the HE's don't require a lot of power, but I can confirm they sound a lot better with the extra gain, at least that's the case with my STX.  When I set the gain to high, the headphones come alive, and sound even better when I set it to extra high gain.

Hello,
 
Have anyone tried setting 600Ohm output on ZxR using low impedance headphones (30-300)? Any sound difference/improvement? I'am afraid to damage headphones so always keep that setting <300 as warning says  

 

[germanium]

  Hello,
 
Have anyone tried setting 600Ohm output on ZxR using low impedance headphones (30-300)? Any sound difference/improvement? I'am afraid to damage headphones so always keep that setting <300 as warning says  

if you match the volumes between the 2 gain options there is little difference in quality. unlike the Asus STX the different gain levels do appear to be set in hardware as there is a click in the relay during gain changes. Current feedback amp are little affected by gain changes & there frequency response will be flat to oblivion no matter what gain you choose