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The DX90 by iBasso . . . Sound impressions . . . . . . . New Firmware, 2.5.1 . . .
May 6, 2014 at 9:17 AM Post #751 of 3,155
headwhacker said:
 

EDIT: I think the BUF634 used in the output stage is to boost current. The voltage part is handled by the OPA1611.
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What you state is the "purpose" of each chip in the circuit, not the "control factor" using a battery source: From a fixed/limited capacity battery power source, the current output is controlled/limited by voltage and load resistance (load).
 
May 6, 2014 at 9:19 AM Post #752 of 3,155
headwhacker said:
  I wish it's that simple. How can you quantify SQ? :)
 
I think it's safe to say DX90 is very close to DX100 and far from DX50. 
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Quote:
pudu said:
So, ... ... ... ... DX50 ... ... ... DX90 DX100 ?

How do they think up these names?
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It's obvious DX90 is closer to DX100
 
DX100 - DX90 =  DX10
 
DX90 -  DX50 = DX40
 
DX40 >> DX10
 
So therefore, DX90 is closer to DX100 
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Sheesh, It's simple as my proof.  Oh lord, we needs some edumacation in here.  Public schooling not cutting it guys?  
rolleyes.gif
 
 
May 6, 2014 at 9:36 AM Post #754 of 3,155
jrazmar said:
   
borrego, how does the dx90 sounds with the PK1? Does it have enough juice to bring out its full potential or does it need an amp like your Arrow? I have an OK1 and I wonder how it will synergize with the iBasso. If it cannot drive it well then I might buy an amp instead for my J3. 
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I do not know how it is for the OK1. But for my PK1 (clone), the additional sound stage (especially depth), and instrument separation brought out by the Arrow 4G is very obvious. I would say DX90 built-in amp drive it "just fine" without clipping or so, but the sound stage is much smaller. Considering the PK1's strength is its sound stage, I would say the DX90 built-in amp is limiting it.
 
I think I have now finished EPH-100 "burn in". Even with the EPH-100, the increase sound stage with the Arrow 4G is very obvious comparing to the DX90 built-in amp.
 
If you listen to vocal mainly and prefer a closer, more intimate presentation, then the DX90 built-in amp would be fine.
 
Please note that I set the DX90 volume to maximum when connecting to the Arrow 4G.
 
May 6, 2014 at 9:48 AM Post #755 of 3,155
I do the opposite with slim.Max volume on pico,around 220-230 on dx90.The built in amp of ibasso is quite good but i don't think it can compete with $400,$500,$600 amps.Nevertheless,the detail the dual dacs of ibasso pump is insane!They provide the clay to built totl soundsystem.
 
May 6, 2014 at 10:02 AM Post #756 of 3,155
I think the the main weakness of the DX90 built-in amp is its rely on the DAC level volume control. Although ESS could claim bit perfect with the DAC level volume control, this implementation cause a lower S/N from the OPA1602 part of the circuit onward.
 
I charge the DX90 with my IPAD 4 charger. When listening to through the EPH-100 and  DX90 built-in amp while charging, I can detect some current noise at 160 volume setting. Not so when listening through DX90 LINE OUT (max vol) + Arrow 4G at low gain setting.
 
May 6, 2014 at 10:10 AM Post #757 of 3,155
It's a digital volume control. I think it's a necessary evil so they don't have to use an analog volume control which has it's own problems (e.g. channel imbalance at low volume, another component that would introduce noise.
 
If you can keep the volume at or above 200, I think it's not a problem.
 
May 6, 2014 at 2:29 PM Post #758 of 3,155
borrego said:
  I think the the main weakness of the DX90 built-in amp is its rely on the DAC level volume control. Although ESS could claim bit perfect with the DAC level volume control, this implementation cause a lower S/N from the OPA1602 part of the circuit onward.
 
I charge the DX90 with my IPAD 4 charger. When listening to through the EPH-100 and  DX90 built-in amp while charging, I can detect some current noise at 160 volume setting. Not so when listening through DX90 LINE OUT (max vol) + Arrow 4G at low gain setting.
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The It's not the DAC V control but the dirty PS. How can you blame the V control when it doesn't have the issue with it's own PS. It's not current related but induced noise from the cheap supply.
 
May 6, 2014 at 7:44 PM Post #759 of 3,155
goodvibes said:
  The It's not the DAC V control but the dirty PS. How can you blame the V control when it doesn't have the issue with it's own PS. It's not current related but induced noise from the cheap supply.
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You don't understand, do you?
 
Using the DAC volume control at any volume setting but max will decrease the S/N ratio from the point of the OPA1602, making it more susceptible to the "dirty" external PS. Using DAC built-in volume control is never a "Hi-Fi" circuit design. You can ask people at the Dedicated Source Components forum.
 
DAC built-in volume control is NOT equal to the implementation of using a dedicated digital volume control chip at later (pre-amp) section of the circuit.
 
Using external AMP, I can max out the DAC volume to maximize S/N, making it much less susceptible to "dirty" PS.
 
I suppose you do use shielded coaxle or twisted pair interconnect cables, don't you? Why don't you use straight bare wire interconnects, and say it is the dirty electromagnetic environment which causes the noise?
 
May 6, 2014 at 7:52 PM Post #760 of 3,155
borrego said:
   
You don't understand, do you?
 
Using the DAC volume control at any volume setting but max will decrease the S/N ratio from the point of the OPA1602, making it more susceptible to the "dirty" external PS. Using DAC built-in volume control is never a "Hi-Fi" circuit design. You can ask people at the Dedicated Source Components forum.
 
DAC built-in volume control is NOT equal to the implementation of using a dedicated digital volume control chip at later (pre-amp) section of the circuit.
 
Using external AMP, I can max out the DAC volume to maximize S/N, making it much less susceptible to "dirty" PS.
 
I suppose you do use shielded coaxle or twisted pair interconnect cables, don't you? Why don't you use straight bare wire interconnects, and say it is the dirty electromagnetic environment which causes the noise?
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May 6, 2014 at 8:26 PM Post #761 of 3,155
I am not trying to be a smart axx. This is the impression thread and I am trying to share how one can really use the impressive S/N of the DX90 LO.
 
I am also not complaining. I already owned the Arrow 4G before I bought the DX90. And I did know it used DAC level volume control before purchase
 
May 6, 2014 at 8:33 PM Post #762 of 3,155
The fact that I don't hear current noise fron my IPAD 4 powered by the same "dirty" 5V power supply says something. The IPAD 4 also uses digital volume control. The difference is the IPAD 4 uses a single chip DAC/AMP/VC which drives headphone right after the chip. So its VC actually is at the last gain stage of the circuit.
 
May 6, 2014 at 8:51 PM Post #763 of 3,155
Nice find. Very informative. I guess the fear of audiophiles about digital volume control was anchored in the old DACs which only has 16 bits. On modern 32 bit DAC like the Sabres, digital volume control is not as bad as what people thought it was. Now it's just funny to think that a few claims that digital volume control is not true hifi especially for Line level signal.
 
May 6, 2014 at 8:56 PM Post #764 of 3,155
Contrary to what common people think, the type of volume control implementation which provides the best S/N is the type of inline/cable built in volume slider one could find on cheap IEMs. Of course those cheap sliding potentialmeter has capacitance/inductance issue which would adversely affect the sound in different ways.
 
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