[DannyBai]

I've been doing some tests with the ZO2+Pro 900's and I get the same distortion and it does sound horrible.  I have the older version ZO2.3
I don't remember having this issue when I first received it.  When I don't have it on high gain using HO, it really doesn't get loud enough.  Weird.  

 

[phrosty]

Quote:

The sub-bass sounds like high bass and no longer vibrates my ears. It sounds like it's trying to force bass out of headphones that normally don't have much bass.

I decided to update my review with some simple RMAA tests, and the rolloff should be inaudible by contour 8 (yellow on the ZO):
 

 
Compared to my PenguinAmp the ZO boosts about 10Hz higher. If your Clip is similar (unfortunately I do not have one to test), this could be the reason you're hearing more high bass.

 

[RPGWiZaRD]

Quote:

I decided to update my review with some simple RMAA tests, and the rolloff should be inaudible by contour 8 (yellow on the ZO):
 

 
Compared to my PenguinAmp the ZO boosts about 10Hz higher. If your Clip is similar (unfortunately I do not have one to test), this could be the reason you're hearing more high bass.

 
Seriously, how do you do these tests! I want to do the same for ZO2.1. Is it enough to have a Realtek onboard source and these ZO2 amps to make the kind of comparision you seem to do here. Do you first, just unplug ZO2, measure with the soundcard and then you plug the amp and measure again and then compare and subtract the results? I just don't understand how this program will pick up signal changes made outside of the source, I don't see how that's possible. xD
 
 

 

[MizMoxie]

Quote:

 
After you posted this, I paired my ZO2 with my HFI-580s again and it sounds great! That's really weird.
Don't get me wrong...DigiZoid made a great product that works well with most headphones, just not the Pro 900.
 
 
Here's the thread I made with video.
http://www.head-fi.org/t/594082/digizoid-zo2-pro-900-distortion-vs-fiio-e5-e11-video

First off, I would like to know why you are using the EQ on your clip to boost bass, and have ZO set at green (flat frequency response)? Not only is it stated in the manual to set the EQ on your player to flat b/c it could cause distortion (*especially* with your clip set to 10-15dB), but using it like that totally defeats the purpose of ZO! Instead, set your EQ to flat, and use ZO's contours to boost bass.
 
Secondly, why do you need the volume on your clip set to 90%??? The Pro 900's only have an impedance of 40ohms. When I use my HD280 Pro's (which are 64ohm), 65% is on the borderline of being unbearably loud! If the volume is set that high, plus you're in high gain mode... that will definitely cause distortion b/c the headphones are being entirely overdriven! And then with the 10-15dB of bass boost on top of that... no wonder it sounds like that!  

 
 

 

[phrosty]

Quote:

Seriously, how do you do these tests! I want to do the same for ZO2.1. Is it enough to have a Realtek onboard source and these ZO2 amps to make the kind of comparision you seem to do here. Do you first, just unplug ZO2, measure with the soundcard and then you plug the amp and measure again and then compare and subtract the results? I just don't understand how this program will pick up signal changes made outside of the source, I don't see how that's possible. xD

 
An onboard Realtek codec obviously won't give the best quality, but I imagine it should work fine enough if you're only measuring frequency response.
 
If your sound card supports it, make sure it's set to a line-out or speaker option. Use line-in instead of mic-in if there are separate settings or jacks.
 
Put a male->male between your line-out and line-in, and click the "Playback/Recording" button in RMAA. When you get to the test results screen, save them and repeat with the ZO plugged in. When that test completes, load the non-ZO results into another column. Then you can click the buttons on the right side, and it'll graph both of them together.
 
If you have a resistor adapter, I believe you can plug one in before the line-in to simulate headphones.

 

[RPGWiZaRD]

Quote:

 
An onboard Realtek codec obviously won't give the best quality, but I imagine it should work fine enough if you're only measuring frequency response.
 
If your sound card supports it, make sure it's set to a line-out or speaker option. Use line-in instead of mic-in if there are separate settings or jacks.
 
Put a male->male between your line-out and line-in, and click the "Playback/Recording" button in RMAA. When you get to the test results screen, save them and repeat with the ZO plugged in. When that test completes, load the non-ZO results into another column. Then you can click the buttons on the right side, and it'll graph both of them together.
 
If you have a resistor adapter, I believe you can plug one in before the line-in to simulate headphones.

 
Yea I tried to quickly set it up like that connecting from the default green line-out jack to in this case the blue line-in jack so yes it has a separate "line-in" but I run into a problem that it seemed to only output sound into the left channel so it wouldn't let me run the test. I'm also wondering with this realtek onboard what device to select as "plugged in device"... speaker/headphones or line-in when configured like that. Also I'm worried about the volume levels, I hope I won't be able to damage anything especially with amp in-between. What volume to use on the amp vs volume set on the soundcard etc?
 
At least I've previously measured the FR response for the onboard chip only by playback without connecting to line-out and it showed nearly perfectly straight line so shouldn't be a problem for only measuring the frequency response balance which I'm only interested in.
 

 

[phrosty]

Quote:

I'm worried about the volume levels, I hope I won't be able to damage anything especially with amp in-between. What volume to use on the amp vs volume set on the soundcard etc?

 
I set the PC to 0dBFS (maximum volume) and the ZO to low gain with its volume turned all the way down. I slowly raised the volume on the ZO until RMAA's calibration screen showed acceptable levels. I suppose if you've got a ZO without a volume control, you should lower the volume on the PC instead.
 
Also, here's another one for everyone who prefers one gain mode over another:
 

 
Basically the same, although it looks like the volume control adds some odd probably-inaudible wobbliness to low-gain.

 

[MizMoxie]

Quote:

 
I set the PC to 0dBFS (maximum volume) and the ZO to low gain with its volume turned all the way down. I slowly raised the volume on the ZO until RMAA's calibration screen showed acceptable levels. I suppose if you've got a ZO without a volume control, you should lower the volume on the PC instead.
 
Also, here's another one for everyone who prefers one gain mode over another:
 

 
Basically the same, although it looks like the volume control adds some odd probably-inaudible wobbliness to low-gain.

Uhm.... something there isn't right, and it doesn't have anything to do with the ZO's volume control. The volume level on the PC is way too high, and you're overdriving the ZO's inputs. Lower the volume on the PC, and set the ZO's volume to max in low gain mode (purple). This should give you better results.
 
BTW... the max voltage you can put on ZO's input is 250mVrms in high gain mode, and 1.0mVrms in low gain mode. 
 

 

[RPGWiZaRD]

OK thanks for the reply, here's my results from ZO2.1, I also measured bypass mode just out of interest, looks like it only mutes the very high frequencies a little, otherwise it's the same as unplugging ZO2.1:
 
(Click to zoom in)

 

 
As seen here, ZO2.1 even boosted the bass at the lowest level but yea this has been very audible to my ears all the time so no news there. But yea it's also got capability to add even more bass than ZO2.3 (this case it seems 15~16dB(!)) but this my ears also have agreed with but it doesn't tell ofc about the characteristics, the bass response on 2.1 seems punchier compared to ZO2.3. I personally prefer the sound of 2.1 to be honest but it did require some burn-in, at first the bass was very overhelming and the amp lacked transparency.
 
I wonder how it would sound like if the centered bass peak was moved forward by like 10Hz or so, currently it's quite deeply centered. I mean 25Hz at the max setting, that's VERY low. ^^

 

[torrez15]

Also a 900 user here. just started testing with an LOD and while it does sound cleaner it doesn't get near loud enough. Ill be sticking with the HO i think

 

[MrNurse]

Quote:

First off, I would like to know why you are using the EQ on your clip to boost bass, and have ZO set at green (flat frequency response)? Not only is it stated in the manual to set the EQ on your player to flat b/c it could cause distortion (*especially* with your clip set to 10-15dB), but using it like that totally defeats the purpose of ZO! Instead, set your EQ to flat, and use ZO's contours to boost bass.
 
Secondly, why do you need the volume on your clip set to 90%??? The Pro 900's only have an impedance of 40ohms. When I use my HD280 Pro's (which are 64ohm), 65% is on the borderline of being unbearably loud! If the volume is set that high, plus you're in high gain mode... that will definitely cause distortion b/c the headphones are being entirely overdriven! And then with the 10-15dB of bass boost on top of that... no wonder it sounds like that!  

 
 

 
1. The first thing I did when I received my ZO2- put my EQ on flat. As I stated, I've tried every combination.
After your post, I tried it again in hopes that somehow the distortion would go away.
Results with flat EQ:
High gain w/max contour: Distortion w/bass-heavy songs. The higher I raise the volume, the more distortion there is. Impact is similar to my Clip+ w/E11 (bass boost 2), Flat EQ. The difference is that I can use my Clip+ EQ for even more bass w/o any distortion. 
Low gain: There's slight distortion/muddiness, but it's slightly better than at high gain. Bass is the same level as previously stated.
 
2. 90% was in relation to standard(cheap) headphones on standard MP3 players w/o an amp, 100% being the max. It's on the higher end of listening volume but not the maximum.
My Clip+ can reach over 120% volume levels.
In short, on a scale of 1-10 with anything over 10 being too loud, the volume is at about a 9.
 
As someone posted in my thread that I made about my distortion problem, I'm not the only one experiencing this with the ZO2 + Pro 900 combination.
 

 

[phrosty]

Quote:

Uhm.... something there isn't right, and it doesn't have anything to do with the ZO's volume control. The volume level on the PC is way too high, and you're overdriving the ZO's inputs. Lower the volume on the PC, and set the ZO's volume to max in low gain mode (purple). This should give you better results.
 
BTW... the max voltage you can put on ZO's input is 250mVrms in high gain mode, and 1.0mVrms in low gain mode. 

Once again, thank you. You were absolutely correct! Images are all fixed.

 

[RPGWiZaRD]

Haha, why do I get the feeling no1 even looks at the quick start guide. xD There it says to start with 25% source volume. For future it would probably be good to try raise the input tolerance if possible though, it seems to be fairly low but I've not compared all other competitor's amps and don't know what those can whitstand either.

 

[torrez15]

Quote:

Haha, why do I get the feeling no1 even looks at the quick start guide. xD There it says to start with 25% source volume. For future it would probably be good to try raise the input tolerance if possible though, it seems to be fairly low but I've not compared all other competitor's amps and don't know what those can whitstand either.

doesn't say that in the guide...

 

[RPGWiZaRD]

Quote:

doesn't say that in the guide...

Yea my bad it seems, I'm pretty sure it used to for the older ZO versions. 
 
BTW what do you think about the volume level regarding low gain? Is it suitable or could it perhaps be raised? (talking mainly with LOD use, since I'm unable to test this myself I'd be curious what other people's experiences are). Personally if possible I'd see it great to have low gain to provide roughly the same volume when used in conjunction with headphone jack vs not using ZO, I wonder if people got any headroom for a gain rise or not especially with more sensitive IEMs. What volume level on ZO2.3 provides you "normal" listening volume in low gain when used with LOD?